Reproducible,biocompatible medical materials from biologically derived polysaccharides: Processing and Characterization

Natural polysaccharides like chitosan and dextran have garnered considerable interest in biomedical applications due to their biocompatibility, biodegradability, and nontoxicity. Nonetheless, the development of a reproducible class of medical devices from these materials is challenging and has had limited success. Chitosan and dextran are inherently variable and synthesis using these materials is prone to inconsistencies. In this study, we put forward a robust product development regimen that allows these natural materials to be developed into a reproducible class of biomaterials. First, an array of validated characterization methods (Proton Nuclear Magnetic Resonance, titrations, Ultraviolet spectroscopy, Size Exclusion Chromatography—Multi-Angle Light Scattering, Size Exclusion Chromatography—Refractive Index, and proprietary methods) were developed that allowed rigorous specifications to be set for unprocessed chitosan and dextran, chitosan and dextran intermediates, and chemically modified materials—acrylated chitosan (aCHN) and oxidized dextran (oDEX). Second, a robust and reproducible synthesis scheme involving various in-process controls was developed to chemically modify the unprocessed polysaccharides. Third, purification methods to remove byproducts and low-molecular-weight impurities for both aCHN and oDEX were developed. The study presents a viable strategy for converting variable, natural materials into a reproducible class of biomaterials that can be applied in various biomedical applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48454.     

Private Justice: Losing Our Day in Court

In the early days of the dispute resolution movement—the ‘80s and ‘90s—the concern was often expressed that we were developing a system of “second‐class justice” for those who couldn't afford the courts. The wealthy, of course, would continue to have access to the “first‐class justice” that the public courts provided.     

The impact of childhood symptoms of conduct disorder on driver aggression in adulthood

Background

Despite limited empirical investigation, existing scientific literature suggests that individuals with a history or current diagnosis of conduct disorder (CD) may be more likely to demonstrate reckless and aggressive driving. Much of the limited research in this field examines the impact of childhood CD on driver behaviour and collision risk in young adults. Few if any, studies assess the impact of this disorder on driver behaviour beyond age 21 years. The current research is a population-based study of the impact of CD symptoms during childhood on the risk of engaging in driver aggression during adulthood.

Methods

Data are based on telephone interviews with 5230 respondents who reported having driven in the past year. Data are derived from the 2011–2013 cycles of the CAMH Monitor, an ongoing cross-sectional survey of adults in Ontario, Canada aged 18 years and older. A binary logistic regression analysis of self-reported driver aggression in the previous 12 months was conducted, consisting of measures of demographic characteristics, driving exposure, problem substance use, alcohol- and drug-impaired driving, symptoms of attention deficit hyperactivity disorder, and childhood (before age 15) symptoms of CD.

Results

When entered with demographic characteristics, driving exposure, and other potential confounders, childhood symptoms of CD increased the odds of reporting driver aggression more than two-fold (adjusted OR = 2.12). Exploratory analyses of the interaction between childhood symptoms of CD and age was not a significant predictor of driver aggression.

Conclusions

Results suggest that symptoms of CD during childhood are associated with significantly increased odds of self-reported driver aggression during adulthood. Limitations and future directions of the research are discussed.     

Correlating indoor and outdoor temperature and humidity in a sample of buildings in tropical climates

The incidence of several respiratory viral infections has been shown to be related to climate. Because humans spend most of their time indoors, measures of indoor climate, rather than outdoor climate, may be better predictors of disease incidence and transmission. Therefore, understanding the relationship between indoor and outdoor climate will help illuminate their influence on the seasonality of diseases caused by respiratory viruses. Indoor-outdoor relationships between temperature and humidity have been documented in temperate regions, but little information is available for tropical regions, where seasonal patterns of respiratory viral diseases differ. We have examined indoor-outdoor correlations of temperature, relative humidity (RH), and absolute humidity (AH) over a 1-year period in each of seven tropical cities. Across all cities, the average monthly indoor temperature was 25 ± 3°C (mean ± standard deviation) with a range of 20–30°C. The average monthly indoor RH was 66 ± 9% with a range of 50–78%, and the average monthly indoor AH was 15 ± 3 g/m³ with a range of 10–23 g/m³. Indoor AH and RH were linearly correlated with outdoor AH when the air conditioning (AC) was off, suggesting that outdoor AH may be a good proxy of indoor humidity in the absence of AC. All indoor measurements were more strongly correlated with outdoor measurements as distance from the equator increased. Such correlations were weaker during the wet season, especially when AC was in operation. These correlations will provide insight for assessing the seasonality of respiratory viral infections using outdoor climate data, which is more widely available than indoor data, even though transmission of these diseases mainly occurs indoors.     

Varietal discrimination of Chilean wines by direct injection mass spectrometry analysis combined with multivariate statistics

A simple, direct injection, electrospray ionization Fourier transform mass spectrometry (ESI FT-MS) method, in combination with multivariate statistics, was used for the characterization and sorting of Chilean wines. 47 commercial red wines labelled as Cabernet Sauvignon, Carménère, Syrah, and Pinot noir, and 25 white wines of the varieties Chardonnay and Sauvignon blanc were diluted, directly infused into the mass spectrometer, and analyzed in negative ion mode. The signature ions used for statistical analyses were manually filtered out from the signals with m/z ratios over 10%. The results of principal component analysis allowed a good sorting of white wines, but not so in the case of reds. The main three principal components explained 96.82% and 85.65% of the variance for white and red wines, respectively. Instead, linear discriminant analysis, allowed the correct discrimination of 100.00% of white and 95.74% of red samples. The validation of these results using the leave-one-out cross-validation method gave lower percentages of correct classification (76.00% and 61.70% of white and red samples respectively), suggesting that some of the wine samples analyzed might have been blends of more than one variety. Consequently, ESI FT-MS direct injection analysis of wines can be used for sample discrimination, but requires a stronger mathematical model built with spectral information of pure and blended samples before improving the percentages of classification.     

Guidelines and recommendations for indoor use of fuel cells and hydrogen systems

Hydrogen energy applications often require that systems are used indoors (e.g., industrial trucks for materials handling in a warehouse facility, fuel cells located in a room, or hydrogen stored and distributed from a gas cabinet). It may also be necessary or desirable to locate some hydrogen system components/equipment inside indoor or outdoor enclosures for security or safety reasons, to isolate them from the end-user and the public, or from weather conditions.Using of hydrogen in confined environments requires detailed assessments of hazards and associated risks, including potential risk prevention and mitigation features. The release of hydrogen can potentially lead to the accumulation of hydrogen and the formation of a flammable hydrogen-air mixture, or can result in jet-fires. Within Hyindoor European Project, carried out for the EU Fuel Cells and Hydrogen Joint Undertaking safety design guidelines and engineering tools have been developed to prevent and mitigate hazardous consequences of hydrogen release in confined environments. Three main areas are considered: Hydrogen release conditions and accumulation, vented deflagrations, jet fires and including under-ventilated flame regimes (e.g., extinguishment or oscillating flames and steady burns). Potential RCS recommendations are also identified.     

Electrospray ionization mass spectrometry fingerprinting of Brazilian cacha?as produced in copper alembic and in stainless-steel column stills

Brazilian cacha?a can be produced in two different ways: distilled in stainless steel column or in copper alembic stills. We evaluated 36 samples of commercial non-aged cacha?as: 18 samples of sweetened cacha?as distilled in stainless steel column, and 18 samples distilled in copper alembic stills. Fingerprints were obtained through electrospray ionization mass spectrometry by recording the intensity of the 15 most abundant ions. Principal component analysis was applied to the data and separated the samples in two groups. However, after sample standardization with sugar (20?g?L^?1), it was not possible to group them by type of distillation. The results showed that the technique applied did not allow differentiation of cacha?as based on the distillation system, but for the presence or absence of sugar in them.     

Introduction of sulfhydryl groups and disulfide linkage to mungbean 8Sα globulin and effects on physicochemical and functional properties

Sulfhydryl groups and disulfide bond were introduced in mungbean's major storage protein, 8Sα globulin, by protein engineering to improve structural stability and functional properties. Five modified proteins or mutants (F59C, I99C, A213C, one free sulfhydryl group; I99C/A213, one disulfide bridge; F59C/I99C/A213C, one free sulfhydryl group and one disulfide linkage) were expressed in Escherichia coli at a yield similar to that of the unmodified protein or wild type (WT) in soluble form (38%). The number of introduced groups in the mutants was confirmed by Ellman analysis. Mutant and WT proteins exhibited similar elution patterns on gel filtration indicating their trimeric native conformation. Mutants had 2 to 3.8 °C higher T_m values than WT and were digested by chymotrypsin at 52–58% in 60 min but exhibited different digestion patterns. All mutants showed greater hardness of heat-induced gels than WT, especially I99C/A213C and F59C/I99C/A213C. Results indicate the improved structural stability of the modified 8Sα globulin.     

Hydrogel‐mediated formation of living cartilage template for endochondral initiation

The use of hydrogel in cartilage tissue engineering is especially popular due to its high hydrophilic property which is similar to native cartilage matrix. Alginate hydrogel was used as a transient scaffold material to facilitate chondrocyte proliferation into a three‐dimensional scaffold‐free living hyaline cartilaginous graft (LhCG). As LhCG is purely cell‐based and has a marked resemblance to native hyaline cartilage, it served as an excellent in vitro platform for studying the endochondral ossification pathway. Due to the complexity of events involved throughout endochondral ossification, this study only focuses on early stages of the process where it involves chondrocyte hypertrophy and blood vessel invasion. Human umbilical vein endothelial cells (HUVECs) were selected as the target cells for possible endothelialization in the LhCG template. They were seeded onto the LhCG construct and subjected to vascular endothelial growth factor (VEGF) treatment. Results suggested that VEGF is indeed a potent driving force for initiation of the endochondral pathway. It alone is sufficient to induce hypertrophy in chondrocytes and the corresponding expression of osteogenic genes with or without the presence of HUVECs in the LhCG template. On the other hand, the effect of HUVECs in the LhCG system was less evident. It is hypothesized that this is attributed to the preservation of anti‐angiogenic properties in primary chondrocytes from the LhCG construct, inhibiting HUVECs from endothelialization in the LhCG+HUVEC construct. Based on the outcome from this study, it is recommended that hypertrophy in chondrocytes should be induced prior to endothelial cell introduction so that the microenvironment will be altered to favor angiogenesis within the cartilaginous template. © 2013 Society of Chemical Industry     

CF-GGA: A grouping genetic algorithm for the cell formation problem

In manufacturing, the machine-part cell formation (MPCF) problem addresses the issues surrounding the formation of part families based on the processing requirements of the components, and the identification of machine groups based on their ability to process specific part families. Past research has shown that one key aspect of attaining efficient groupings of parts and machines is the block-diagonalization of the given machine-part (MP) incidence matrix. This paper presents and tests a grouping genetic algorithm (GGA) for solving the MPCF problem and gauges the quality of the GGA's solutions using the measurements of efficiency (Chandrasekharan and Rajagopalan 1986a) and efficacy (Kumar and Chandrasekharan 1990). The GGA in this study, CF-GGA, a grouping genetic algorithm for the cell formation problem, performs very well when applied to a variety of problems from the literature. With a minimal number of parameters and a straightforward encoding, CF-GGA is able to match solutions with several highly complex algorithms and heuristics that were previously employed to solve these problems.