Αρχειοθήκη ιστολογίου

Αναζήτηση αυτού του ιστολογίου

Παρασκευή 13 Μαΐου 2016

Radiological response is associated with better long-term outcomes and is a potential treatment target in patients with small bowel Crohn's disease

The American Journal of Gastroenterology

from #Medicine via ola Kala on Inoreader http://ift.tt/1R0QeEx
via IFTTT

Does neighborhood fast-food outlet exposure amplify inequalities in diet and obesity? A cross-sectional study

American Journal of Clinical Nutrition

from #Medicine via ola Kala on Inoreader http://ift.tt/1rJmMP0
via IFTTT

The use of capsule endoscopy in the emergency department as a triage of patients with GI bleeding

Gastrointestinal Endoscopy

from #Medicine via ola Kala on Inoreader http://ift.tt/1R0Qcwh
via IFTTT

Association between severity of obstructive sleep apnea and blood markers of liver injury

Clinical Gastroenterology and Hepatology

from #Medicine via ola Kala on Inoreader http://ift.tt/1rJmOGr
via IFTTT

Dysphagia in patients with acute ischemic stroke: early dysphagia screening may reduce stroke-related pneumonia and improve stroke outcomes

Cerebrovascular Diseases

from #Medicine via ola Kala on Inoreader http://ift.tt/1R0QeEt
via IFTTT

Applicability of hepatitis C virus RNA viral load thresholds for 8-week treatments in patients with chronic hepatitis C virus genotype 1 infection

Clinical Infectious Diseases

from #Medicine via ola Kala on Inoreader http://ift.tt/1rJmOq5
via IFTTT

Management and outcomes of leaks after oesophagectomy

British Journal of Surgery

from #Medicine via ola Kala on Inoreader http://ift.tt/1R0QcfZ
via IFTTT

Prevalence of overweight and obesity among children and adolescents with intellectual disabilities: a systematic review and meta-analysis

Obesity Reviews

from #Medicine via ola Kala on Inoreader http://ift.tt/1rJmOpV
via IFTTT

The inter-rater reliability of the International Classification of Functioning, Disability and Health set for spinal cord injury nursing.

The International Classification of Functioning, Disability and Health (ICF) has potential to be used as a clinical assessment instrument directly. However, difficulty in operationalizing the ICF qualifiers has led to unsatisfactory inter-rater reliability of ICF instruments in previous studies. The ICF set for spinal cord injury (SCI) nursing contains a group of categories that can reflect the functioning of SCI patients from the perspective of nurses. The aim of this study was to explore the inter-rater reliability of the ICF set for SCI nursing. Detailed measuring guidelines were prepared for each category of the ICF set. Two trained nurses then used the ICF set to independently rate 40 SCI patients within the first 3 days after their admission. The results showed that the percentage of the observed agreement between the nurses ranged from 42.5 to 100% (median 75%, interquartile range 62.5-87.5%). The weighted [kappa] ranged from -0.03 to 1.00 (median 0.68, interquartile range 0.45-0.84). A total of 50 categories (79.4%) showed weighted [kappa] greater than 0.4 and 39 categories (61.9%) had weighted [kappa] greater than 0.6. The medians of the weighted [kappa] for the body functions, body structures, activity and participation and environmental factors components were 0.6, 0.64, 0.84, and 0.11, respectively. This study indicated that the inter-rater reliability of the ICF set for SCI nursing was acceptable. Establishment of detailed measuring guidelines could help reduce the differences between raters. Simpler and clearer measuring guidelines are recommended and the definitions of some categories need to be clarified in future studies. Copyright (C) 2016 Wolters Kluwer Health, Inc. All rights reserved.

from #Medicine via ola Kala on Inoreader http://ift.tt/1TSrfrB
via IFTTT

Cognitive reserve and preinjury educational attainment: effects on outcome of community-based rehabilitation for longer-term individuals with acquired brain injury.

The cognitive reserve hypothesis has been proposed to account for the mismatch between brain pathology and its clinical expression. The aim of the current research was to explore, in a longitudinal data set, the effects of level of educational attainment before brain injury (cognitive reserve) and clinical factors on the level of rehabilitation-induced changes in disability and community integration. Participants in receipt of postacute rehabilitation were assessed at induction to the service and again at between 14 and 18 months of follow-up while still in service on changes in aspects of their abilities, adjustment and participation (Mayo Portland Adaptability Indices) and community integration (Community Integration Questionnaire). Controlling for type and severity of injury, age at onset of injury and duration of time since injury, participants with higher previous educational attainment showed significantly greater changes over the course of rehabilitation on adjustment to their injury and participation, but not on abilities, or community integration following postacute rehabilitation. Level of education would appear to be an important element of cognitive reserve in brain injury that serves to aid responses to postacute rehabilitation in terms of an individual's adjustment to disability and participation. Copyright (C) 2016 Wolters Kluwer Health, Inc. All rights reserved.

from #Medicine via ola Kala on Inoreader http://ift.tt/1rJlK5v
via IFTTT

The relationship between static posturography measures and specific cognitive domains in individuals with multiple sclerosis.

There are still limitations as to the understanding of the cognitive-postural control relationship in people with multiple sclerosis (PwMS). The aim of the current study' was to examine the relationship between cognition with measures of posturography in PwMS. The study was cross-sectional comprising 253 PwMS (162 women) with a mean age of 42.0 (SD=14.0). All participants completed a computerized cognitive test battery designed to evaluate multiple cognitive domains (Mindstreams; NeuroTrax) and static posturography tests (Zebris Medical GmbH). PwMS were divided into four levels of disability on the basis of their Expanded Disability Status Scale (EDSS) score: very mild (EDSS: 0-2.0), mild (EDSS: 2.5-3.5), moderate (EDSS: 4.0-5.5), and severe (EDSS: 6.0-6.5; using a walking aid). Significant correlations were observed between cognitive domains and posturography measures. However, the correlations were different between the disability subgroups. For the mild group, significant correlation scores were observed between the balance measures to the executive function and motor skills cognitive domains (Pearson's [rho]=~0.3 and ~0.4, respectively). As for the moderate group, significant correlation scores were observed in memory and verbal function (Pearson's [rho]=~0.4 and ~0.4, respectively). Attention was the only cognitive domain correlated significantly with posturography measures in the severe group (Pearson's [rho]=~0.55). Our study found that posturography measures are related to cognition in PwMS. However, the associations vary in terms of cognitive domains and disability levels. Copyright (C) 2016 Wolters Kluwer Health, Inc. All rights reserved.

from #Medicine via ola Kala on Inoreader http://ift.tt/1TSrfrv
via IFTTT

Kullback–Leibler divergence and the Pareto–Exponential approximation

Recent radar research interests in the Pareto distribution as a model for X-band maritime surveillance radar clutter returns have resulted in analysis of the asymptotic behaviour of this clutter model. In part...

from #Medicine via ola Kala on Inoreader http://ift.tt/1qhHLXQ
via IFTTT

Carriage rate and methicillin resistance of Staphylococcus aureus in food handlers in Kars City, Turkey

The aim of this study was determine carriage rate and methicillin resistance of Staphylococcus aureus among food handlers. Samples were collected by swabbing the mouth, nasal cavity and hands of food workers. The...

from #Medicine via ola Kala on Inoreader http://ift.tt/1NsLVY7
via IFTTT

Expression of scavenger receptor A in rat’s liver tissue during acute obstructive cholangitis and its significance

Acute obstructive cholangitis (AOC) is a severe disease that leads to sepsis, shock and multiple organ dysfunction syndrome. Liver is the largest and the major organ for the defense mechanisms during the sepsi...

from #Medicine via ola Kala on Inoreader http://ift.tt/1qhHLXz
via IFTTT

Scientists’ personality, values, and well-being

Scientists play an important role in modern society. However, only a small number of their psychological characteristics, such as personality traits, have been investigated; hence, further investigation is req...

from #Medicine via ola Kala on Inoreader http://ift.tt/1NsLVXZ
via IFTTT

Aspergillus leaf spot of field bindweed (Convolvulus arvensis L.) caused by Aspergillus niger in China

Leaf spot was found on field bindweed (Convolvulus arvensis L.) in Shihezi City, Xinjiang Province, China, during the summer of 2015. Pathogens were isolated from the infected leaves of field bindweed and identif...

from #Medicine via ola Kala on Inoreader http://ift.tt/1qhHLqH
via IFTTT

P53 and the defenses against genome instability caused by transposons and repetitive elements

The recent publication by Wylie et al. is reviewed, demonstrating that the p53 protein regulates the movement of transposons. While this work presents genetic evidence for a piRNA-mediated p53 interaction with transposons in Drosophila and zebrafish, it is herein placed in the context of a decade or so of additional work that demonstrated a role for p53 in regulating transposons and other repetitive elements. The line of thought in those studies began with the observation that transposons damage DNA and p53 regulates DNA damage. The presence of transposon movement can increase the rate of evolution in the germ line and alter genes involved in signal transduction pathways. Transposition can also play an important role in cancers where the p53 gene function is often mutated. This is particularly interesting as recent work has shown that de-repression of repetitive elements in cancer has important consequences for the immune system and tumor microenvironment.

Thumbnail image of graphical abstract

There is a history of associating p53 with transposon activity repression and of transposons spreading p53 binding sites throughout the genome. Presumably this emanates from p53 regulating DNA damage, and the DNA damage associated with transposition. Wylie et al. present evidence for direct interaction between p53 and transposon regulating piRNA.



from #Medicine via ola Kala on Inoreader http://ift.tt/1Ypy6Kt
via IFTTT

Issue Information



from #Medicine via ola Kala on Inoreader http://ift.tt/1rJkJdB
via IFTTT

Toxins, Vol. 8, Pages 150: Sensitive, Rapid, Quantitative and in Vitro Method for the Detection of Biologically Active Staphylococcal Enterotoxin Type E

Staphylococcus aureus is a major bacterial cause of clinical infections and foodborne illnesses through its production of a group of enterotoxins (SEs) which cause gastroenteritis and also function as superantigens to massively activate T cells. In the present study, we tested Staphylococcal enterotoxin type E (SEE), which was detected in 17 of the 38 suspected staphylococcal food poisoning incidents in a British study and was the causative agent in outbreaks in France, UK and USA. The current method for detection of enterotoxin activity is an in vivo monkey or kitten bioassay; however, this expensive procedure has low sensitivity and poor reproducibility, requires many animals, is impractical to test on a large number of samples, and raises ethical concerns with regard to the use of experimental animals. The purpose of this study is to develop rapid sensitive and quantitative bioassays for detection of active SEE. We apply a genetically engineered T cell-line expressing the luciferase reporter gene under the regulation of nuclear factor of activated T-cells response element (NFAT-RE), combined with a Raji B-cell line that presents the SEE-MHC (major histocompatibility complex) class II to the engineered T cell line. Exposure of the above mixed culture to SEE induces differential expression of the luciferase gene and bioluminescence is read out in a dose dependent manner over a 6-log range. The limit of detection of biologically active SEE is 1 fg/mL which is 109 times more sensitive than the monkey and kitten bioassay.

from #Medicine via ola Kala on Inoreader http://ift.tt/1Wujxr2
via IFTTT

Toxins, Vol. 8, Pages 152: New Insights into VacA Intoxication Mediated through Its Cell Surface Receptors

Helicobacter pylori (H. pylori), a major cause of gastroduodenal diseases, produces VacA, a vacuolating cytotoxin associated with gastric inflammation and ulceration. The C-terminal domain of VacA plays a crucial role in receptor recognition on target cells. We have previously identified three proteins (i.e., RPTPα, RPTPβ, and LRP1) that serve as VacA receptors. These receptors contribute to the internalization of VacA into epithelial cells, activate signal transduction pathways, and contribute to cell death and gastric ulceration. In addition, other factors (e.g., CD18, sphingomyelin) have also been identified as cell-surface, VacA-binding proteins. Since we believe that, following interactions with its host cell receptors, VacA participates in events leading to disease, a better understanding of the cellular function of VacA receptors may provide valuable information regarding the mechanisms underlying the pleiotropic actions of VacA and the pathogenesis of H. pylori-mediated disease. In this review, we focus on VacA receptors and their role in events leading to cell damage.

from #Medicine via ola Kala on Inoreader http://ift.tt/1R0Onzs
via IFTTT

Toxins, Vol. 8, Pages 151: Ellagitannins in Cancer Chemoprevention and Therapy

It is universally accepted that diets rich in fruit and vegetables lead to reduction in the risk of common forms of cancer and are useful in cancer prevention. Indeed edible vegetables and fruits contain a wide variety of phytochemicals with proven antioxidant, anti-carcinogenic, and chemopreventive activity; moreover, some of these phytochemicals also display direct antiproliferative activity towards tumor cells, with the additional advantage of high tolerability and low toxicity. The most important dietary phytochemicals are isothiocyanates, ellagitannins (ET), polyphenols, indoles, flavonoids, retinoids, tocopherols. Among this very wide panel of compounds, ET represent an important class of phytochemicals which are being increasingly investigated for their chemopreventive and anticancer activities. This article reviews the chemistry, the dietary sources, the pharmacokinetics, the evidence on chemopreventive efficacy and the anticancer activity of ET with regard to the most sensitive tumors, as well as the mechanisms underlying their clinically-valuable properties.

from #Medicine via ola Kala on Inoreader http://ift.tt/1qhA7MU
via IFTTT

Toxins, Vol. 8, Pages 149: Determination of Asymmetric and Symmetric Dimethylarginine in Serum from Patients with Chronic Kidney Disease: UPLC-MS/MS versus ELISA

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthesis, and its structural isomer symmetric dimethylarginine (SDMA) are uremic toxins accumulating in chronic kidney disease (CKD) patients. The objective of this study was to develop and validate a robust UPLC-MS/MS method for the simultaneous determination of ADMA and SDMA in human serum. Chromatographic separation after butyl ester derivatization was achieved on an Acquity UPLC BEH C18 column, followed by tandem mass spectrometric detection. After validation, the applicability of the method was evaluated by the analysis of serum samples from 10 healthy controls and 77 CKD patients on hemodialysis (CKD5HD). Both ADMA (0.84 ± 0.19 µM vs. 0.52 ± 0.07 µM) and SDMA concentrations (2.06 ± 0.82 µM vs. 0.59 ± 0.13 µM) were significantly (p < 0.001) elevated in CKD5HD patients compared to healthy controls. In general, low degrees of protein binding were found for both ADMA and SDMA. In addition, an established commercially available ELISA kit was utilized on the same samples (n = 87) to compare values obtained both with ELISA and UPLC-MS/MS. Regression analysis between these two methods was significant (p < 0.0001) but moderate for both ADMA (R = 0.78) and SDMA (R = 0.72).

from #Medicine via ola Kala on Inoreader http://ift.tt/1rJibfA
via IFTTT

Sensors, Vol. 16, Pages 692: A Nonlinear Framework of Delayed Particle Smoothing Method for Vehicle Localization under Non-Gaussian Environment

In this paper, a novel nonlinear framework of smoothing method, non-Gaussian delayed particle smoother (nGDPS), is proposed, which enables vehicle state estimation (VSE) with high accuracy taking into account the non-Gaussianity of the measurement and process noises. Within the proposed method, the multivariate Student's t-distribution is adopted in order to compute the probability distribution function (PDF) related to the process and measurement noises, which are assumed to be non-Gaussian distributed. A computation approach based on Ensemble Kalman Filter (EnKF) is designed to cope with the mean and the covariance matrix of the proposal non-Gaussian distribution. A delayed Gibbs sampling algorithm, which incorporates smoothing of the sampled trajectories over a fixed-delay, is proposed to deal with the sample degeneracy of particles. The performance is investigated based on the real-world data, which is collected by low-cost on-board vehicle sensors. The comparison study based on the real-world experiments and the statistical analysis demonstrates that the proposed nGDPS has significant improvement on the vehicle state accuracy and outperforms the existing filtering and smoothing methods.

from #Medicine via ola Kala on Inoreader http://ift.tt/1R0OnzA
via IFTTT

Nanomaterials, Vol. 6, Pages 90: Aggregation and Colloidal Stability of Commercially Available Al2O3 Nanoparticles in Aqueous Environments

The aggregation and colloidal stability of three, commercially-available, gamma-aluminum oxide nanoparticles (γ-Al2O3 NPs) (nominally 5, 10, and 20–30 nm) were systematically examined as a function of pH, ionic strength, humic acid (HA) or clay minerals (e.g., montmorillonite) concentration using dynamic light scattering and transmission electron microscopy techniques. NPs possess pH-dependent surface charges, with a point of zero charge (PZC) of pH 7.5 to 8. When pH < PZC, γ-Al2O3 NPs are colloidally stable up to 100 mM NaCl and 30 mM CaCl2. However, significant aggregation of NPs is pronounced in both electrolytes at high ionic strength. In mixed systems, both HA and montmorillonite enhance NP colloidal stability through electrostatic interactions and steric hindrance when pH ≤ PZC, whereas their surface interactions are quite limited when pH > PZC. Even when pH approximates PZC, NPs became stable at a HA concentration of 1 mg·L−1. The magnitude of interactions and dominant sites of interaction (basal planes versus edge sites) are significantly dependent on pH because both NPs and montmorillonite have pH-dependent (conditional) surface charges. Thus, solution pH, ionic strength, and the presence of natural colloids greatly modify the surface conditions of commercial γ-Al2O3 NPs, affecting aggregation and colloidal stability significantly in the aqueous environment.

from #Medicine via ola Kala on Inoreader http://ift.tt/1rJidnA
via IFTTT

Energies, Vol. 9, Pages 365: Energy Performance of Verandas in the Building Retrofit Process

Passive solar elements for both direct and indirect gains, are systems used to maintain a comfortable living environment while saving energy, especially in the building energy retrofit and adaptation process. Sunspaces, thermal mass and glazing area and orientation have been often used in the past to guarantee adequate indoor conditions when mechanical devices were not available. After a period of neglect, nowadays they are again considered as appropriate systems to help face environmental issues in the building sector, and both international and national legislation takes into consideration the possibility of including them in the building planning tools, also providing economic incentives. Their proper design needs dynamic simulation, often difficult to perform and time consuming. Moreover, results generally suffer from several uncertainties, so quasi steady-state procedures are often used in everyday practice with good results, but some corrections are still needed. In this paper, a comparative analysis of different solutions for the construction of verandas in an existing building is presented, following the procedure provided by the slightly modified and improved Standard EN ISO 13790:2008. Advantages and disadvantages of different configurations considering thermal insulation, windows typology and mechanical ventilation systems are discussed and a general intervention strategy is proposed. The aim is to highlight the possibility of using sunspaces in order to increase the efficiency of the existing building stock, considering ease of construction and economic viability.

from #Medicine via ola Kala on Inoreader http://ift.tt/1R0Onzv
via IFTTT

JMSE, Vol. 4, Pages 34: Recent Advances in the Study of Marine Microbial Biofilm: From the Involvement of Quorum Sensing in Its Production up to Biotechnological Application of the Polysaccharide Fractions

The present review will explore the most relevant findings on marine microbial biofilm, with particular attention towards its polysaccharide fraction, namely exopolysaccharide (EPS). EPSs of microbial origin are ubiquitous in nature, possess unique properties and can be isolated from the bacteria living in a variety of habitats, including fresh water or marine environments, extreme environments or different soil ecosystems. These biopolymers have many application in the field of biotechnology. Several studies showed that the biofilm formation is closely related to quorum sensing (QS) systems, which is a mechanism relying on the production of small molecules defined as "autoinducers" that bacteria release in the surrounding environment where they accumulate. In this review, the involvement of microbial chemical communication, by QS mechanism, in the formation of marine biofilm will also be discussed.

from #Medicine via ola Kala on Inoreader http://ift.tt/1rJid7g
via IFTTT

Toxins, Vol. 8, Pages 152: New Insights into VacA Intoxication Mediated through Its Cell Surface Receptors

ag

Helicobacter pylori (H. pylori), a major cause of gastroduodenal diseases, produces VacA, a vacuolating cytotoxin associated with gastric inflammation and ulceration. The C-terminal domain of VacA plays a crucial role in receptor recognition on target cells. We have previously identified three proteins (i.e., RPTPα, RPTPβ, and LRP1) that serve as VacA receptors. These receptors contribute to the internalization of VacA into epithelial cells, activate signal transduction pathways, and contribute to cell death and gastric ulceration. In addition, other factors (e.g., CD18, sphingomyelin) have also been identified as cell-surface, VacA-binding proteins. Since we believe that, following interactions with its host cell receptors, VacA participates in events leading to disease, a better understanding of the cellular function of VacA receptors may provide valuable information regarding the mechanisms underlying the pleiotropic actions of VacA and the pathogenesis of H. pylori-mediated disease. In this review, we focus on VacA receptors and their role in events leading to cell damage.

from #Medicine via ola Kala on Inoreader http://ift.tt/1R0Onzs
via IFTTT

Sustainability, Vol. 8, Pages 476: Importance of Actors and Agency in Sustainability Transitions: A Systematic Exploration of the Literature

This article explores the role of actors and agency in the literature on sustainability transitions. We reviewed 386 journal articles on transition management and sustainability transitions listed in Scopus from 1995 to 2014. We investigate the thesis that actors have been neglected in this literature in favor of more abstract system concepts. Results show that this thesis cannot be confirmed on a general level. Rather, we find a variety of different approaches, depending on the systemic level, for clustering actors and agency as niche, regime, and landscape actors; the societal realm; different levels of governance; and intermediaries. We also differentiate between supporting and opposing actors. We find that actor roles in transitions are erratic, since their roles can change over the course of time, and that actors can belong to different categories. We conclude by providing recommendations for a comprehensive typology of actors in sustainability transitions.

from #Medicine via ola Kala on Inoreader http://ift.tt/1R0Onzq
via IFTTT

Sensors, Vol. 16, Pages 689: Comprehensive Comparisons of Satellite Data, Signals, and Measurements between the BeiDou Navigation Satellite System and the Global Positioning System

The Chinese BeiDou navigation satellite system (BDS) aims to provide global positioning service by 2020. The combined use of BDS and Global Positioning System (GPS) is proposed to provide navigation service with more stringent requirements. Actual satellite data, signals and measurements were collected for more than one month to analyze the positioning service qualities from both BDS and GPS. In addition to the conversions of coordinate and timing system, five data quality analysis (DQA) methods, three signal quality analysis (SQA) methods, and four measurement quality analysis (MQA) methods are proposed in this paper to improve the integrated positioning performance of BDS and GPS. As shown in the experiment results, issues related to BDS and GPS are resolved by the above proposed quality analysis methods. Thus, the anomalies in satellite data, signals and measurements can be detected by following the suggested resolutions to enhance the positioning performance of the combined use of BDS and GPS in the Asia Pacific region.

from #Medicine via ola Kala on Inoreader http://ift.tt/1rJibfC
via IFTTT

IJERPH, Vol. 13, Pages 499: Fever and Pain Management in Childhood: Healthcare Providers’ and Parents’ Adherence to Current Recommendations

In order to evaluate the adherence of healthcare providers and parents to the current recommendations concerning fever and pain management, randomized samples of 500 healthcare providers caring for children and 500 families were asked to complete an anonymous questionnaire. The 378 health care providers (HCPs) responding to the survey (75.6%) included 144 primary care pediatricians (38.1%), 98 hospital pediatricians (25.9%), 62 pediatric residents (16.4%), and 71 pediatric nurses (19.6%); the 464 responding parents (92.8%) included 175 whose youngest (or only) child was ≤5 years old (37.7%), 175 whose youngest (or only) child was aged 6–10 years (37.7%), and 114 whose youngest (or only) child was aged 11–14 years (24.6%). There were gaps in the knowledge of both healthcare providers and parents. Global adherence to the guidelines was lower among the pediatric nurses than the other healthcare providers (odds ratio 0.875; 95% confidence interval 0.795–0.964). Among the parents, those of children aged 6–10 and 11–14 years old, those who were older, and those without a degree answered the questions correctly significantly less frequently than the others. These findings suggest that there is an urgent need to improve the dissemination of the current recommendations concerning fever and pain management among healthcare providers and parents in order to avoid mistaken and sometimes risky attitudes, common therapeutic errors, and the unnecessary overloading of emergency department resources. Pediatric nurses and parents with older children, those who are older, and those with a lower educational level should be the priority targets of educational programmes.

from #Medicine via ola Kala on Inoreader http://ift.tt/1R0Oprd
via IFTTT

Toxins, Vol. 8, Pages 149: Determination of Asymmetric and Symmetric Dimethylarginine in Serum from Patients with Chronic Kidney Disease: UPLC-MS/MS versus ELISA

ag

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthesis, and its structural isomer symmetric dimethylarginine (SDMA) are uremic toxins accumulating in chronic kidney disease (CKD) patients. The objective of this study was to develop and validate a robust UPLC-MS/MS method for the simultaneous determination of ADMA and SDMA in human serum. Chromatographic separation after butyl ester derivatization was achieved on an Acquity UPLC BEH C18 column, followed by tandem mass spectrometric detection. After validation, the applicability of the method was evaluated by the analysis of serum samples from 10 healthy controls and 77 CKD patients on hemodialysis (CKD5HD). Both ADMA (0.84 ± 0.19 µM vs. 0.52 ± 0.07 µM) and SDMA concentrations (2.06 ± 0.82 µM vs. 0.59 ± 0.13 µM) were significantly (p < 0.001) elevated in CKD5HD patients compared to healthy controls. In general, low degrees of protein binding were found for both ADMA and SDMA. In addition, an established commercially available ELISA kit was utilized on the same samples (n = 87) to compare values obtained both with ELISA and UPLC-MS/MS. Regression analysis between these two methods was significant (p < 0.0001) but moderate for both ADMA (R = 0.78) and SDMA (R = 0.72).

from #Medicine via ola Kala on Inoreader http://ift.tt/1rJibfA
via IFTTT

Polymers, Vol. 8, Pages 163: The Effect of Lithium Iodide to the Properties of Carboxymethyl κ-Carrageenan/Carboxymethyl Cellulose Polymer Electrolyte and Dye-Sensitized Solar Cell Performance

ag

This study was undertaken to investigate the solid biopolymer electrolytes based on a carboxymethyl κ-carrageenan/carboxymethyl cellulose blend complexed with lithium iodide of various weight ratios. The complexation of the doping salt with the polymer blend was confirmed by Fourier transform infrared spectroscopy. Ionic conductivity of the film was determined by impedance spectroscopy in the frequency range of 10 Hz to 4 MHz and in the temperature range of 303–338 K. The ionic conductivity increased with the increase in lithium iodide concentration as well as temperature. The membrane comprising 30 wt % of lithium iodide was found to give the highest conductivity of 3.89 × 10−3 S·cm−1 at room temperature. The increase in conductivity was associated with the increase in the number as well as the mobility of the charge carries. The conductivity increase with temperature followed the Vogel–Tamman–Fulcher model. The fabricated dye-sensitive solar cell, FTO/TiO2-dye/CMKC/CMCE-LiI (30 wt %) +I2/Pt exhibited the highest conversion efficiency of 0.11% at a light intensity of 100 mW·cm−2. This indicated that the biopolymer blend electrolyte system has potential for use in dye-sensitized solar cells.

from #Medicine via ola Kala on Inoreader http://ift.tt/1rJibfy
via IFTTT

Separations, Vol. 3, Pages 14: Method for the Determination of Benzene Metabolite t,t-Muconic Acid in Urine by HPLC-UV with an Ion Exclusion Column

ag

The benzene metabolite trans,trans-muconic acid (tt-MA) is widely used as a biological indicator of exposure to this xenobiotic. An analytical method was developed and validated for the determination of urinary tt-MA using solid phase extraction onto a Strata SAX cartridge. The analysis was performed by HPLC with an Aminex HPX-87H ion exclusion column and a UV diode array detector. The sample preparation conditions were optimized using a 24−1 factorial design. Comparison of the slopes of standard analytical curves prepared in aqueous solution and urine showed that the biological matrix suppressed the tt-MA signal by around 50%, so the analytical curves were prepared with tt-MA standard at low concentrations in pooled urine. The analytical curves in the range of 5–500 μg·L−1 showed determination coefficients values (R2) > 0.99 for tt-MA standard in water and R2 > 0.98 for tt-MA standards in pooled urine. The coefficients of variation obtained using seven replicates were lower than 3.6%, and recoveries of tt-MA from solutions containing 5, 25, 50 and 100 μg·L−1 of the analyte were in the range 85%–90%, demonstrating the satisfactory precision and accuracy of the method. The limits of detection and quantification were 0.11 and 0.36 µg ·L−1, respectively. The benefits of this new method developed is the possibility of complete chromatographic peak separation for the determination of tt-MA at baseline, without matrix components' interference as normally found in the C18 column. This is the first time that this chromatographic column has been used for the analysis of tt-MA in urine.

from #Medicine via ola Kala on Inoreader http://ift.tt/1rJid75
via IFTTT

Hirnbasissyndrom infolge eines Tumors bei einer 17 Monate alten Deutsch-Holstein-Färse

Eine 17 Monate alte Färse der Rasse Deutsch-Holstein wurde wegen seit einem Tag bestehender Schluckstörungen, geringgradiger Lähmung der Zunge sowie Lidschwellungen vorgestellt. Die klinische Untersuchung ergab eine gestreckte Kopf-Hals-Haltung, hochgradige Salivation, einen reduzierten Zungentonus sowie einen Schlotterkiefer mit vollständigem Ausfall des Schluckreflexes. Am rechten Auge zeigten sich ein herabhängend wirkendes Oberlid, mukopurulenter Ausfluss, Expositionskeratitis, Hornhauttrübung und Miosis. Linksseitig bestanden ein mittelgradiger Exophthalmus und geringgradiger muköser Nasenausfluss. Bei der neurologischen Untersuchung waren multiple Kopfnervenausfälle festzustellen, die für das Vorliegen eines Hirnbasissyndroms sprachen. Röntgenologisch ließ sich ventral des Siebbeins eine klar abgegrenzte, weichteildichte Verschattung von ca. 5 cm Durchmesser mit Verdacht auf intraneurokranialen Ursprung nachweisen, die sich rhinoskopisch mit unebener, geröteter, teils von eitrigem Exsudat bedeckter Oberfläche darstellte. Die pathomorphologische Untersuchung des euthanasierten Rindes bestätigte das Vorliegen einer Neoplasie, die von der Fossa hypophysialis des Corpus ossis basisphenoidalis bis in den Bereich ventral des Siebbeins reichte. Die histopathologischen Befunde passten zu einem sogenannten „kleinzelligen blauen Rundzelltumor"....

from #Medicine via ola Kala on Inoreader http://ift.tt/1TJJcpg
via IFTTT

Ahead of print: Niederfeld-magnetresonanztomographische Untersuchung durchdringender Hufverletzungen...

Ziel der Studie war, die diagnostische Aussagekraft der mittels Niederfeld-Magnetresonanztomographie (MRT) erhobenen Befunde bei septischen Erkrankungen im Hufbereich nach durchdringenden Verletzungen (Nageltritt) zu überprüfen. Material und Methoden: Bei 10 Pferden mit Verletzungen im Hufbereich wurden die MRT-Befunde mittels klinischer, chirurgischer, röntgenologischer, sonographischer und computertomographischer Befunde und/oder postmortaler histologischer Untersuchung validiert. Ergebnisse: Am genauesten ließ sich eine Beteiligung des Strahlbeins nachweisen, die am besten in der fettunterdrückten Sequenz (Short-Tau-Inversion-Recovery-Sequenz, STIR) ermittelt wurde. Defekte der tiefen Beugesehne waren ausgezeichnet nachweisbar, aber unspezifischer als Veränderungen des Strahlbeins. Sie ließen sich am besten in transversalen T2-gewichteten Fast-Spin-Echo-Sequenzen (T2w FSE) nachvollziehen. Der Stichkanal war in sämtlichen Fällen in allen Ebenen erkennbar. Auch hier erwies sich die T2w FSE als gut geeignet. Am wenigsten deutlich konnte die septische Bursitis nachvollzogen werden. Eine Erkrankung der Bursa war am besten in der sagittalen Ebene erkennbar. Schlussfolgerung und klinische Relevanz: Die MRT-Diagnostik von Erkrankungen im Hufbereich nach Verletzung durch Fremdkörper (vor allem Nageltritt) stellt eine zuverlässige Untersuchungsmethode zur Absicherung der Diagnose dar. Dabei eignet sich eine transversale T2w FSE am besten zum Nachweis eines Stichkanals und Sehnendefekts. Für die Diagnostik der Bursitis sind der Stichkanalverlauf und sekundäre Reaktionen des Strahlbeins ausschlaggebend. Fettunterdrückte Sequenzen können eine Knochenbeteiligung gut nachweisen, wenn der Stichkanal nicht direkt bis auf den Knochen zu verfolgen ist. Die beschriebenen Fälle verdeutlichen, dass bei durchdringenden Verletzungen im Hufbereich eine MRT-Untersuchung angezeigt sein kann, wenn die Beteiligung von Strukturen vermutet wird, die eine schlechte Prognose bedingen. Nur die MRT erlaubt intravital eine Beurteilung der verschiedenen Strukturen innerhalb der Hornkapsel. Diese Information wiederum ist essenziell bei der Entscheidungsfindung für eine gezielte Therapie bzw. einer Vermeidung unnötiger Behandlungen....

from #Medicine via ola Kala on Inoreader http://ift.tt/1OnakOK
via IFTTT

Paclitaxel-coated balloon fistuloplasty versus plain balloon fistuloplasty only to preserve the patency of arteriovenous fistulae used for haemodialysis (PAVE): study protocol for a randomised controlled trial

The initial therapy for a stenosis in an arteriovenous fistula used for haemodialysis is radiological balloon dilatation or angioplasty. The benefit of angioplasty is often short-lived, intervention-free survi...

from #Medicine via ola Kala on Inoreader http://ift.tt/1TJJdty
via IFTTT

Employment Outcomes After Critical Illness: An Analysis of the Bringing to Light the Risk Factors and Incidence of Neuropsychological Dysfunction in ICU Survivors Cohort.

wk-health-logo.gif

Objectives: To characterize survivors' employment status after critical illness and to determine if duration of delirium during hospitalization and residual cognitive function are each independently associated with decreased employment. Design: Prospective cohort investigation with baseline and in-hospital clinical data and follow-up at 3 and 12 months. Setting: Medical and surgical ICUs at two tertiary-care hospitals. Patients: Previously employed patients from the Bringing to Light the Risk Factors and Incidence of Neuropsychological Dysfunction in ICU Survivors study who survived a critical illness due to respiratory failure or shock were evaluated for global cognition and employment status at 3- and 12-month follow-up. Measurements and Main Results:: We used multivariable logistic regression to evaluate independent associations between employment at both 3 and 12 months and global cognitive function at the same time point, and delirium during the hospital stay. At 3-month follow-up, 113 of the total survival cohort of 448 (25%) were identified as being employed at study enrollment. Of these, 94 survived to 12-month follow-up. At 3- and 12-month follow-up, 62% and 49% had a decrease in employment, 57% and 49% of whom, respectively, were newly unemployed. After adjustment for physical health status, depressive symptoms, marital status, level of education, and severity of illness, we did not find significant predictors of employment status at 3 months, but better cognition at 12 months was marginally associated with lower odds of employment reduction at 12 months (odds ratio, 0.49; p = 0.07). Conclusions: Reduction in employment after critical illness was present in the majority of our ICU survivors, approximately half of which was new unemployment. Cognitive function at 12 months was a predictor of subsequent employment status. Further research is needed into the potential relationship between the impact of critical illness on cognitive function and employment status. Copyright (C) by 2016 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. All Rights Reserved.

from #Medicine via ola Kala on Inoreader http://ift.tt/1qhCPC8
via IFTTT

Vaccines, Vol. 4, Pages 17: Comprehensive Characterization of Reference Standard Lots of HIV-1 Subtype C Gp120 Proteins for Clinical Trials in Southern African Regions

Two HIV-1 subtype C gp120 protein candidates were the selected antigens for several experimental vaccine regimens now under evaluation in HVTN 100 Phase I/II clinical trial aiming to support the start of the HVTN 702 Phase IIb/III trial in southern Africa, which is designed to confirm and extend the partial protection seen against HIV-1 infection in the RV144 Thai trial. Here, we report the comprehensive physicochemical characterization of the gp120 reference materials that are representative of the clinical trial materials. Gp120 proteins were stably expressed in Chinese Hamster Ovary (CHO) cells and subsequently purified and formulated. A panel of analytical techniques was used to characterize the physicochemical properties of the two protein molecules. When formulated in the AS01 Adjuvant System, the bivalent subtype C gp120 antigens elicited 1086.C- and TV1.C-specific binding antibody and CD4+ T cell responses in mice. All the characteristics were highly representative of the Clinical Trial Materials (CTM). Data from this report demonstrate the immunogenicity of the gp120 antigens, provide comprehensive characterization of the molecules, set the benchmark for assessment of current and future CTM lots, and lay the physicochemical groundwork for interpretation of future clinical trial data.

from #Medicine via ola Kala on Inoreader http://ift.tt/1WujBav
via IFTTT

Water, Vol. 8, Pages 198: A Methodology to Assess and Evaluate Rainwater Harvesting Techniques in (Semi-) Arid Regions

Arid and semi-arid regions around the world face water scarcity problems due to lack of precipitation and unpredictable rainfall patterns. For thousands of years, rainwater harvesting (RWH) techniques have been applied to cope with water scarcity. Researchers have used many different methodologies for determining suitable sites and techniques for RWH. However, limited attention has been given to the evaluation of RWH structure performance. The aim of this research was to design a scientifically-based, generally applicable methodology to better evaluate the performance of existing RWH techniques in (semi-) arid regions. The methodology integrates engineering, biophysical and socio-economic criteria using the Analytical Hierarchy Process (AHP) supported by the Geographic Information System (GIS). Jessour/Tabias are the most traditional RWH techniques in the Oum Zessar watershed in south-eastern Tunisia, which were used to test this evaluation tool. Fifty-eight RWH locations (14 jessr and 44 tabia) in three main sub-catchments of the watershed were assessed and evaluated. Based on the criteria selected, more than 95% of the assessed sites received low or moderate suitability scores, with only two sites receiving high suitability scores. This integrated methodology, which is highly flexible, saves time and costs, is easy to adapt to different regions and can support designers and decision makers aiming to improve the performance of existing and new RWH sites.

from #Medicine via ola Kala on Inoreader http://ift.tt/223kqqw
via IFTTT

Forests, Vol. 7, Pages 107: Rating a Wildfire Mitigation Strategy with an Insurance Premium: A Boreal Forest Case Study

Risk analysis entails the systematic use of historical information to determine the frequency, magnitude and effects of unexpected events. Wildfire in boreal North America is a key driver of forest dynamics and may cause very significant economic losses. An actuarial approach to risk analysis based on cumulative probability distributions was developed to reduce the adverse effects of wildfire. To this effect, we developed spatially explicit landscape models to simulate the interactions between harvest, fire and forest succession over time in a boreal forest of eastern Canada. We estimated the amount of reduction of timber harvest necessary to build a buffer stock of sufficient size to cover fire losses and compared it to an insurance premium estimated in units of timber volume from the probability of occurrence and the amount of damage. Overall, the timber harvest reduction we applied was much more costly than the insurance premium even with a zero interest rate. This is due to the fact that the insurance premium is directly related to risk while the timber harvest reduction is not and, as a consequence, is much less efficient. These results, especially the comparison with a standard indicator such as an insurance premium, have useful implications at the time of choosing a mitigation strategy to protect timber supplies against risk without overly diminishing the provision of services from the forest. They are also promoting the use of insurance against disastrous events in forest management planning.

from #Medicine via ola Kala on Inoreader http://ift.tt/1WujAmS
via IFTTT

Resources, Vol. 5, Pages 19: Critical Minerals and Energy–Impacts and Limitations of Moving to Unconventional Resources

The nexus of minerals and energy becomes ever more important as the economic growth and development of countries in the global South accelerates and the needs of new energy technologies expand, while at the same time various important minerals are declining in grade and available reserves from conventional mining. Unconventional resources in the form of deep ocean deposits and urban ores are being widely examined, although exploitation is still limited. This paper examines some of the implications of the transition towards cleaner energy futures in parallel with the shifts through conventional ore decline and the uptake of unconventional mineral resources. Three energy scenarios, each with three levels of uptake of renewable energy, are assessed for the potential of critical minerals to restrict growth under 12 alternative mineral supply patterns. Under steady material intensities per unit of capacity, the study indicates that selenium, indium and tellurium could be barriers in the expansion of thin-film photovoltaics, while neodymium and dysprosium may delay the propagation of wind power. For fuel cells, no restrictions are observed.

from #Medicine via ola Kala on Inoreader http://ift.tt/223kq9Z
via IFTTT

Algorithms, Vol. 9, Pages 33: Mining Branching Rules from Past Survey Data with an Illustration Using a Geriatric Assessment Survey for Older Adults with Cancer

We construct a fast data mining algorithm that can be used to identify high-frequency response patterns in historical surveys. Identification of these patterns leads to the derivation of question branching rules that shorten the time required to complete a survey. The data mining algorithm allows the user to control the error rate that is incurred through the use of implied answers that go along with each branching rule. The context considered is binary response questions, which can be obtained from multi-level response questions through dichotomization. The algorithm is illustrated by the analysis of four sections of a geriatric assessment survey used by oncologists. Reductions in the number of questions that need to be asked in these four sections range from 33% to 54%.

from #Medicine via ola Kala on Inoreader http://ift.tt/1WujADq
via IFTTT

Sensors, Vol. 16, Pages 691: Planar Position Sensor Based on Mono Sensing Electrode and Hybrid-Frequency Excitation

A new way of measuring planar position for micrometric and sub-micrometric applications is presented with a mono sensing electrode and hybrid-frequency excitation. The sensing theory and operation principle are described and summarized, and a printed circuit board (PCB) sensor prototype is built and tested. It is shown by the experimental results that a very simple structure and geometric relationship are achieved. Meanwhile, displacement sensitivity on an order of 1.50 mV per micron and measurement repeatability better than 0.002 mm are easily fulfilled for a square zone of 256 mm2, making it a valuable alternative measurement device candidate for flexible and low-cost planar position detection.

from #Medicine via ola Kala on Inoreader http://ift.tt/223knLn
via IFTTT

IJERPH, Vol. 13, Pages 498: Brazilian Green Propolis Improves Antioxidant Function in Patients with Type 2 Diabetes Mellitus

Propolis contains a variety of bioactive components and possesses many biological properties. This study was designed to evaluate potential effects of Brazilian green propolis on glucose metabolism and antioxidant function in patients with type 2 diabetes mellitus (T2DM). In the 18-week randomized controlled study, enrolled patients with T2DM were randomly assigned to Brazilian green propolis group (900 mg/day) (n = 32) and control group (n = 33). At the end of the study, no significant difference was found in serum glucose, glycosylated hemoglobin, insulin, aldose reductase or adiponectin between the two groups. However, serum GSH and total polyphenols were significantly increased, and serum carbonyls and lactate dehydrogenase activity were significantly reduced in the Brazilian green propolis group. Serum TNF-α was significantly decreased, whereas serum IL-1β and IL-6 were significantly increased in the Brazilian green propolis group. It is concluded that Brazilian green propolis is effective in improving antioxidant function in T2DM patients.

from #Medicine via ola Kala on Inoreader http://ift.tt/1WujA6b
via IFTTT

Medical Sciences, Vol. 4, Pages 10: First Evidence for the Disease-Stage, Cell-Type, and Virus Specificity of microRNAs during Human Immunodeficiency Virus Type-1 Infection

The potential involvement of host microRNAs (miRNAs) in HIV infection is well documented, and evidence suggests that HIV modulates and also dysregulates host miRNAs involved in maintaining the host innate immune system. Moreover, the dysregulation of host miRNAs by HIV also effectively interferes directly with the host gene expression. In this study, we have simultaneously evaluated the expression of host miRNAs in both CD4+ and CD8+ T-cells derived from HIV-positive (HIV+) individuals (viremic and aviremic individuals while receiving highly active antiretroviral therapy (HAART), therapy-naïve long-term non-progressors (LTNP), and HIV-negative (HIV–) healthy controls. miRNAs were run on Affymetrix V2 chips, and the differential expression between HIV+ and HIV− samples, along with intergroup comparisons, was derived using PARTEK software, using an FDR of 5% and an adjusted p-value < 0.05. The miR-199a-5p was found to be HIV-specific and expressed in all HIV+ groups as opposed to HIV– controls. Moreover, these are the first studies to reveal clearly the highly discriminatory miRNAs at the level of the disease state, cell type, and HIV-specific miRNAs.

from #Medicine via ola Kala on Inoreader http://ift.tt/223kmHx
via IFTTT

Toxins, Vol. 8, Pages 150: Sensitive, Rapid, Quantitative and in Vitro Method for the Detection of Biologically Active Staphylococcal Enterotoxin Type E

ag

Staphylococcus aureus is a major bacterial cause of clinical infections and foodborne illnesses through its production of a group of enterotoxins (SEs) which cause gastroenteritis and also function as superantigens to massively activate T cells. In the present study, we tested Staphylococcal enterotoxin type E (SEE), which was detected in 17 of the 38 suspected staphylococcal food poisoning incidents in a British study and was the causative agent in outbreaks in France, UK and USA. The current method for detection of enterotoxin activity is an in vivo monkey or kitten bioassay; however, this expensive procedure has low sensitivity and poor reproducibility, requires many animals, is impractical to test on a large number of samples, and raises ethical concerns with regard to the use of experimental animals. The purpose of this study is to develop rapid sensitive and quantitative bioassays for detection of active SEE. We apply a genetically engineered T cell-line expressing the luciferase reporter gene under the regulation of nuclear factor of activated T-cells response element (NFAT-RE), combined with a Raji B-cell line that presents the SEE-MHC (major histocompatibility complex) class II to the engineered T cell line. Exposure of the above mixed culture to SEE induces differential expression of the luciferase gene and bioluminescence is read out in a dose dependent manner over a 6-log range. The limit of detection of biologically active SEE is 1 fg/mL which is 109 times more sensitive than the monkey and kitten bioassay.

from #Medicine via ola Kala on Inoreader http://ift.tt/1Wujxr2
via IFTTT

Metals, Vol. 6, Pages 112: Performances of Green and Eco-Friendly Ramming Pastes in EGA Pots

ag

Consistent and high quality ramming paste products, installed according to optimized procedures, are required for improved operation and longer pot life. However, ramming paste used to be a hazardous product and needs special precautions for handling and application. A 100% eco-friendly cold ramming paste has been developed by Carbone Savoie and tested at Emirates Global Aluminium (EGA) sites. A test has also been developed by Carbone Savoie to follow-up, identify and quantify emissions during the baking of paste up to 1000 °C. Physico-chemical characteristics of various pastes are presented, together with their composition in polycyclic aromatic hydrocarbons (PAH) and volatile organic compounds (VOC), determined by an accredited laboratory and the results of emissions during paste baking. The results of pot operation at the EGA sites show no harmful impact on pot preheat, early operation, or regular operation performance. Pot performance data are given for comparison. The new paste offers a green and clean alternative to harsh chemicals typically associated with the industry.

from #Medicine via ola Kala on Inoreader http://ift.tt/1Wujzzd
via IFTTT

Social Sciences, Vol. 5, Pages 19: Making Communication Strategy Choices in a Fast Evolving Crisis Situation—Results from a Table-Top Discussion on an Anthrax Scenario

ag

This paper aims at clarifying a timely topic of how communication strategy choices are made in evolving, complex crises, such as those caused by terrorism involving chemical, biological, radiological, or nuclear (CBRN) agents. This is done by examining data gathered from a table-top discussion among crisis communication experts, focusing on a scenario of an anthrax attack and analysed qualitatively. The communication experts followed the evolving crisis situation by gathering inputs from various actors in the crisis management network, thereby creating situational understanding, and interpreted these inputs for decision-making on communication strategies. The underlying process of coping with complexity in evolving CBRN terrorism crises can be described as a continuous, dynamic process that can best be explained with a combination of traditional and more modern crisis communication approaches. Strategy-making in crisis situations by communication experts is still largely a black box. In this study, a novel approach of decomposing strategy-making by observing a table-top discussion is chosen to clarify the process. By identifying the core elements involved, a more detailed picture of communication strategy-making is created, thus promoting preparedness and professional resilience in the field.

from #Medicine via ola Kala on Inoreader http://ift.tt/1Wujxay
via IFTTT

Micromachines, Vol. 7, Pages 90: A Comprehensive Review of Optical Stretcher for Cell Mechanical Characterization at Single-Cell Level

ag

This paper presents a comprehensive review of the development of the optical stretcher, a powerful optofluidic device for single cell mechanical study by using optical force induced cell stretching. The different techniques and the different materials for the fabrication of the optical stretcher are first summarized. A short description of the optical-stretching mechanism is then given, highlighting the optical force calculation and the cell optical deformability characterization. Subsequently, the implementations of the optical stretcher in various cell-mechanics studies are shown on different types of cells. Afterwards, two new advancements on optical stretcher applications are also introduced: the active cell sorting based on cell mechanical characterization and the temperature effect on cell stretching measurement from laser-induced heating. Two examples of new functionalities developed with the optical stretcher are also included. Finally, the current major limitation and the future development possibilities are discussed.

from #Medicine via ola Kala on Inoreader http://ift.tt/1WujziM
via IFTTT

Fluids, Vol. 1, Pages 15: Modeling the Viscoelastic Behavior of Amorphous Shape Memory Polymers at an Elevated Temperature

Shape memory polymers (SMPs) are soft active materials, their special property is the ability to hold a temporary shape and when exposed to a suitable trigger, they come back to their original shape. These external stimuli can be temperature, light or electro-magnetic fields. Amorphous SMPs are a class of thermally-activated SMPs that rely on glass transition to retain their temporary shape. Above the glass transition temperature (T > Tg), (amorphous SMPs exhibit finite deformation and viscoelastic behavior. In this work we develop a model to capture the viscoelastic behavior of the amorphous SMPs at elevated temperatures. The model uses an approach that was initially developed to study non-Newtonian viscoelastic fluids. We accomplish this by developing a multi-branch model based on the theory of multiple natural configurations using the maximization of the rate dissipation to determine the evolution of the natural configurations. We apply our model to study several different deformations at an elevated temperature T = 130 °C and show that this approach is able to capture the viscoelastic behavior of these polymers. The predictions of the theory are then compared with experimental results.

from #Medicine via ola Kala on Inoreader http://ift.tt/1WujwTZ
via IFTTT