Damage evolution in polymer due to exposure to high-pressure hydrogen gas

The use of hydrogen as a fuel is increasing exponentially, and the most economical way to store and transport hydrogen for fuel use is as a high-pressure gas. Polymers are widely used for hydrogen distribution and storage systems because they are chemically inert towards hydrogen. However, when exposed to high-pressure hydrogen, some hydrogen diffuses through polymers and occupies the preexisting cavities inside the material. Upon depressurization, the hydrogen trapped inside polymer cavities can cause blistering or cracking by expanding these cavities. A continuum mechanics–based deformation model was deployed to predict the stress distribution and damage propagation while the polymer undergoes depressurization after high-pressure hydrogen exposure. The effects of cavity size, cavity location, and pressure inside the cavity on damage initiation and evolution inside the polymer were studied. The stress and damage evolution in the presence of multiple cavities was also studied, because interaction among cavities alters the damage and stress field. It was found that all these factors significantly change the stress state in the polymer, resulting in different paths for damage propagation. The effect of adding carbon black filler particles and plasticizer on the damage was also studied. It was found that damage tolerance of the polymer increases drastically with the addition of carbon black fillers, but decreases with the addition of the plasticizer.     

A System for Measurement of Isokinetic Strength for Estimation of Load Handling Capacity

This note describes a method for measurement of isokinetic strength for prediction of manual materials handling capacity of individuals. The apparatus used in this methodology and measurement technique are illustrated in detail.     

Ergonomic job design in frequent manual lifting tasks: A microcomputer-based model

The main objective of this paper is to generate ergonomic software that can be used in the design and evaluation of manual materials handling tasks so as to minimize the risk of injury. Specifically, this study is aimed at developing a microcomputer-based model for the design of frequent manual lifting tasks based ont he concept of job saverity index. The microcomputer-based software package is intended to be used by non-experts in the field of MMH. Possible engineering and administrative controls are implemented in the software in case if human lifting abilities are exceeded. The software was written in AutoLISP for the IBM personal computer. The knowledge base of the software is built upon a set of two models which were developed in the present study. The models were based on 2,736 observations.     

IESK-ArDB: a database for handwritten Arabic and an optimized topological segmentation approach

Even though a lot of researches have been conducted in order to solve the problem of unconstrained handwriting recognition, an effective solution is still a serious challenge. In this article, we address two Arabic handwriting recognition-related issues. Firstly, we present IESK-arDB, a new multi-propose off-line Arabic handwritten database. It is publicly available and contains more than 4,000 word images, each equipped with binary version, thinned version as well as a ground truth information stored in separate XML file. Additionally, it contains around 6,000 character images segmented from the database. A letter frequency analysis showed that the database exhibits letter frequencies similar to that of large corpora of digital text, which proof the database usefulness. Secondly, we proposed a multi-phase segmentation approach that starts by detecting and resolving sub-word overlaps, then hypothesizing a large number of segmentation points that are later reduced by a set of heuristic rules. The proposed approach has been successfully tested on IESK-arDB. The results were very promising, indicating the efficiency of the suggested approach.     

Patient safety in outpatient surgery: the viewpoint of the healthcare providers

The objective of this study is to understand the viewpoint of healthcare providers with regard to patient safety in outpatient surgery settings. Two methods were used to gather data from the healthcare providers: (1) questionnaire with open-ended questions about six predefined stages of the patient care process; (2) survey with closed questions. With the first method, the main quality and safety of care issues concerned communication to patients, coordination of reports and forms, patient and staff time pressures and standards of care. The first two stages of the outpatient surgery process, i.e. patient work-up prior to day of surgery and patient admission and preparation on the day of surgery, yielded many more comments than the other four stages. The results of the structured questionnaire show that, overall, the healthcare providers report high quality of care provided by themselves (98%) and their surgery centre (96%). With regard to patient safety (i.e. cancellations of surgeries, patient safety problems and serious mistakes), there was a clear difference in perceptions reported by the physicians vs. the nurses and other staff. Nurses and other staff were more likely to report patient safety problems than physicians. The combination of qualitative data from the initial questionnaire and the quantitative data from the structured questionnaire provides a rather complete view of the outpatient surgery staff perceptions of quality and safety of care. This research highlights the importance of getting input from the healthcare providers regarding the quality and safety of care rather than relying only on traditional measures about patient outcomes.     

Electrospun Azithromycin-Laden Gelatin Methacryloyl Fibers for Endodontic Infection Control

This study was aimed at engineering photocrosslinkable azithromycin (AZ)-laden gelatin methacryloyl fibers via electrospinning to serve as a localized and biodegradable drug delivery system for endodontic infection control. AZ at three distinct amounts was mixed with solubilized gelatin methacryloyl and the photoinitiator to obtain the following fibers: GelMA+5%AZ, GelMA+10%AZ, and GelMA+15%AZ. Fiber morphology, diameter, AZ incorporation, mechanical properties, degradation profile, and antimicrobial action against Aggregatibacter actinomycetemcomitans and Actinomyces naeslundii were also studied. In vitro compatibility with human-derived dental pulp stem cells and inflammatory response in vivo using a subcutaneous rat model were also determined. A bead-free fibrous microstructure with interconnected pores was observed for all groups. GelMA and GelMA+10%AZ had the highest fiber diameter means. The tensile strength of the GelMA-based fibers was reduced upon AZ addition. A similar pattern was observed for the degradation profile in vitro. GelMA+15%AZ fibers led to the highest bacterial inhibition. The presence of AZ, regardless of the concentration, did not pose significant toxicity. In vivo findings indicated higher blood vessel formation, mild inflammation, and mature and thick well-oriented collagen fibers interweaving with the engineered fibers. Altogether, AZ-laden photocrosslinkable GelMA fibers had adequate mechanical and degradation properties, with 15%AZ displaying significant antimicrobial activity without compromising biocompatibility.     

Clinical, statistical and immunocytochemical characterization of giant cell tumour of bone amoung Egyptian population

Clinical and immunocytochemical analysis of twenty eight cases of giant cell tumour of bone was performed in this study. The results revealed that nine of the cases were benign, while the other nineteen were malignant. The female to male ratio was 2.5:1. The average age incidence was 28.18 years. The most common site of occurrence was the femur. anti endothelial antibody revealed negative immunocytochemical reaction of the stromal cells and giant cells for both benign and malignant cases; While using anti-HLA-DR antibody demonstrated positive immune reaction of some of the strumal and giant cells of all the cases examined.     

Bidirectional HMM-based Arabic POS tagging

In this work, we will present a new concept of POS tagging that will be implemented for the Arabic language. Indeed, we will see that in Arabic there are a numerous cases where the determination of the morpho-syntactic state of a word depends on the states of the subsequent words, which represents the theoretical foundation of the approach: how to consider, in addition of the past elements, the future ones. We will then demonstrate how the POS tagging in its statistical application: the HMM, is based mainly on the past elements, and how to combine both direct and reverse taggers to tag the same sequence of words in both senses. Thus, we will propose a hypothesis for the result selecting. In the practical part, we will present, in general, the used resource and the changes made on it. Then we will explain the experiment steps and the parameters collected and presented on graphics, that we will discuss later to lead to the final conclusion.     

Castor oil-based polyurethane coatings containing benzyl triethanol ammonium chloride: synthesis,characterization, and biological properties

In the present work, benzyl triethanol ammonium chloride (BTEAC) was employed as a reactive bactericidal additive for preparing of polyurethane coatings. In this regard, castor oil as a renewable resource-based polyol, polyethylene glycol (PEG1000), and BTEAC were reacted with toluene diisocyanate. Physical, mechanical, and thermal characteristics as well as biocompatibility and antibacterial properties of polyurethanes were evaluated. The prepared polyurethanes showed two-phase structure with soft and hard segments glass transition temperature transitions in the range of 18–70 and 85–153 °C, respectively. Initial modulus and tensile strength were improved for coatings with higher BTEAC content, while elongation at break and thermal stability were decreased. Hydrophilicity of coatings was increased for polyurethanes based on higher content of BTEAC and PEG1000. Polyurethanes with higher BTEAC content showed better cytocompatibility for mouse L929 fibroblast cells. Moreover, coatings with higher hydrophilicity and BTEAC content displayed superior antibacterial activity against both Escherichia coli and Staphylococcus aureus bacteria.     

Use of polymeric materials as a solid phase for radioimmunoassay and immunoradiometric assay techniques

Poly(acrylamide-acrylic acid-acrylonitrile)-ferrous sulfate, p(AM-AA-AN)-FeSO₄·7H₂O, resin was used as a solid phase for estimation of thyroid stimulating hormone (TSH) by radioimmunoassay (RIA) and immunoradiometric assay (IRMA) techniques. Comparison with cellulose particles as a known polymer solid phase was made. The tracers for RIA and IRMA were prepared by radioiodination of TSH antigen and TSH monoclonal antibody, respectively, using Iodogen as oxidizing agent. The tracers were purified by gel chromatography on Sephadex G-25 column. The polyclonal anti-TSH antibody was prepared via immunization of three white New Zealand rabbits with highly purified TSH antigen. The polymer was prepared by addition of aqueous solution of comonomer (AA-AN) and FeSO₄ as cross-linker to polyacrylamide p(AM) and irradiation of the mixture at ambient temperature in a ⁶⁰Co γ-cell. The polymer prepared and cellulose particles were activated using 1,1-carbonyldiimidazole, and these activated particles were coupled with the polyclonal TSH antibody. Optimization and validation of the RIA and IRMA techniques were made.