AB2 and AB5 metal hydride electrodes: a phenomenological model for the cycle life

The variation of the capacities of different metal hydride electrodes as a function of the number of charge-discharge cycles, i.e. the cycle life curve, were quantified using a phenomenological model. This model allows a numerical fit of the measured discharge capacities as a function of the number of cycles. The model determines five independent parameters which describe the electrode cycle life. These parameters are the total and the active start-up capacity, and the activation, oxidation and reduction constants. These are the most interesting characteristics of the electrode for battery applications. This model was applied to the cycle life curve of different AB₂ and AB₅-type electrodes. We found that these parameters depend on the applied discharge current. We must be able to explain this effect. Using X-ray photoelectron spectroscopy depth profiles, we observed strong changes in the surface composition which, together with the increased surface area as a result of pulverization, is responsible for the activation.     

Nanoscopic Characterisation of Individual Endogenous Protein Aggregates in Human Neuronal Cells

The aberrant misfolding and subsequent conversion of monomeric protein into amyloid aggregates characterises many neurodegenerative disorders, including Parkinson's and Alzheimer's diseases. These aggregates are highly heterogeneous in structure, generally of low abundance and typically smaller than the diffraction limit of light (≈250 nm). To overcome the challenges these characteristics pose to the study of endogenous aggregates formed in cells, we have developed a method to characterise them at the nanometre scale without the need for a conjugated fluorophore. Using a combination of DNA PAINT and an amyloid‐specific aptamer, we demonstrate that this technique is able to detect and super‐resolve a range of aggregated species, including those formed by α‐synuclein and amyloid‐β. Additionally, this method enables endogenous protein aggregates within cells to be characterised. We found that neuronal cells derived from patients with Parkinson's disease contain a larger number of protein aggregates than those from healthy controls.     

Effect of organic silicon,methylsulfonylmethane, and glucosamine sulfate in mandibular bone defects in rats

Organic silicon (OS), glucosamine sulfate (GS), and methylsulfonylmethane (MSM) have been related to bone and connective tissue health and have been considered as basic therapy for osteoarthrosis disorders. Therefore, the aim was to analyze the effect of the association of these three components in mandibular bone defects in rats. Nine rats were used for histocompatibility test. In each animal was implanted the composition (70% OS, 15% GS, 15% MSM) and gutta percha (control) under the dorsal subcutaneous tissue. The samples were collected at 7, 14, and 21 days post‐surgery and inflammatory events analyzed. In sequence, the composition was engrafted in mandibular bone defects of nine rats; bone defects without treatment were the control group. Analyses were performed at 7, 14, and 28 days post‐surgery and samples were evaluated by scanning electron microscopy (SEM). For the histocompatibility test, both groups had a moderate inflammatory process at 7 days post‐surgery and mild inflammatory process at 14 and 21 days. But in SEM analysis, the composition promotes an extensive reabsorption in cortical and crest alveolar bone, and great tooth root reabsorption. In conclusion, although the composition had positive result in the histocompatibility test, its direct application in mandibular bone defects caused intense resorption.     

Hyperbranched‐modified epoxy thermosets: Enhancement of thermomechanical and shape‐memory performances

In this study a complete characterization of the thermomechanical and shape‐memory properties of epoxy shape‐memory polymers modified with hyperbranched polymer and aliphatic diamine was performed. Focusing on the mechanical properties that are highly desirable for shape‐memory polymers, tensile behavior until break was analyzed at different temperatures and microhardness and impact strength were determined at room temperature. As regards shape memory performance, the materials were fully characterized at different programming temperatures to study how this influenced the recovery ratio, fixity ratio, shape‐recovery velocity, and switching temperature. Tensile testing revealed a peak in deformability and in the stored energy density at the onset of the glass transition temperature, demonstrating that this is the best programming temperature for obtaining the best shape‐memory performances. The Young's moduli revealed more rigid structures in formulations with higher hyperbranched polymer content, while microhardness showed higher values with increasing hyperbranched polymer content due to the increased crosslinking density. Impact strength was greatly improved as the aliphatic diamine content increases due to the energy dissipation capability of its flexible structure. As regards the shape‐memory properties, increasing the programming temperature has a minor effect on formulations with a lower hyperbranched polymer content and worsens these properties when the hyperbranched polymer content is increased. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44623.     

Comparison of methods for quantifying dental wear caused by erosion and abrasion

Various methods have been applied to evaluate the effect of erosion and abrasion. So, the aim of this study was to check the applicability of stylus profilometry (SP), surface hardness (SH) and focus‐variation 3D microscopy (FVM) to the analysis of human enamel and dentin subjected to erosion/abrasion. The samples were randomly allocated into four groups (n = 10): G1‐enamel/erosion, G2‐enamel/erosion plus abrasion, G3‐dentin/erosion, and G4‐dentin/erosion plus abrasion. The specimens were selected by their surface hardness, and they were subjected to cycles of demineralization (Coca‐Cola®‐60 s) and remineralization (artificial saliva‐60 min). For groups G2 and G4, the remineralization procedures were followed by toothbrushing (150 strokes). The above cycle was repeated 3×/day during 5 days. The samples were assessed using SH, SP, and FVM. For each substrate, the groups were compared using an unpaired t‐test, and Pearson correlation coefficients were calculated (α = 5%). For enamel, both profilometry technique showed greater surface loss when the erosion and abrasion processes were combined (P <0.05). The correlation analysis did not reveal any relationships among SH, SP, and FVM to G2 and G4. There were significant correlation coefficients (–0.70 and –0.67) for the comparisons between the FVM and SH methods in enamel and dentin, respectively, in G1 and G3. Choosing the ideal technique for the analysis of erosion depends on the type of dental substrate. SP was not sufficiently sensitive to measure the effects on dentin of erosion or erosion/abrasion. However, SP, FVM and SH were adequate for the detection of tissue loss and demineralization in enamel. Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc.     

A rail-to-rail differential quasi-digital converter for low-power applications

This paper presents an ultra low power differential voltage-to-frequency converter (dVFC) suitable to be used as a part of a multisensory interface in portable applications. The proposed dVFC has been designed in 1.2-V 0.18-μm CMOS technology, and it works properly over the whole differential input range (0.6 ± 0.6 V) providing an output frequency range of 0.0–0.9 MHz. The system has been tested for temperature variations from ?40 to +120 °C and supply voltage variations of up to 30 %, being the maximum linearity error in the worse case of 0.017 %. Simulations against common mode voltage variations show a deviation in the output frequency of 0.4 %. This dVFC has power consumption below 60 μW, and it includes an enable terminal that sets the system in a sleep mode (180 nW) while no conversion is request. The dVFC occupies an active area of 250 μm × 150 μm.     

POLYMER SOLUBILITY THEORY PREDICTS EFFICIENCY OF RESIDUAL OIL EXTRACTION BY POLAR SOLVENTS

Light paraffinic solvents (C2 to C7) have traditionally been utilized by the petroleum refining industry to extract oils from crude distillation residua. Extracted oils constitute feedstock to lubricants manufacture and, to a lesser extent, additional cracking stock. More recent literature reveals a growing interest in polar, non-hydrocarbon partially oil-soluble solvents such as alcohols, ketones, and esters of lower carboxylic acids. In this work, articles and patents which report the separation of residua into asphalt and extracted oil by means of polar solvents are briefly reviewed, and the separation performance of same of those solvents is correlated to the solute-solvent interaction parameter (ϰ) in the Flory-Huggins theory of polymer solubility. The three dimensional solubility parameter (δ) approach is followed to estimate ϰ for the solvents of interest at the appropriate operating conditions. The saturate, aromatic, and polar compounds fractions of a bitumen are characterized by solubility parameters equal to the values of δ of the solvents or mixtures thereof used by the standard ASTM D-2007 chromatographic fractionation of the deasphaltenated oil (DAO). A mean value of ϰ is found for every DAO-solvent pair, treatment ratio and temperature. For each solvent considered, yields of extracted oil at varying operating conditions (temperature, pressure, solvent /feed ratio) are found to be well correlated to ϰ, in according with theoretical predictions that the lower a value of ϰ a solvent has for a given solute, the better it dissolves the solute and the higher the yield.

It is suggested that this type of approach could supply criteria to select solvents and operating conditions for applications requiring high yields (to produce additional cracking stock) or lower yields but high rejection of metals and heteroatoms (e.g. for lube oil bases extraction).     

Lipid changes during long-term storage of canned tuna (Thunnus alalunga)

 In previous studies fluorescence detection at different excitation/emission maxima during common fish processing has been used. A bathochromic shift towards higher wavelength maxima was observed and measured as the ratio between absorption at two of the maxima tested. This fluorescence ratio (δF) value correlates positively with fish damage. In the present work, the influence of formaldehyde (FA) on the value δF was studied. A model system was set up in which FA reacted at 30°C for 25 days with propylamine and fish muscle. It was observed that FA was less able to produce fluorescent compounds compared with common fish oxidation products that were also tested, i. e. propanal and hexanal. However, in the presence of both lipid oxidation aldehydes, the FA-containing mixtures led to a higher δF value. Model systems consisting of FA and fatty fish (sardine) muscle produced more fluorescence than FA and lean fish (cod), because of the formation of lipid oxidation compounds under the reaction conditions of the former systems. It is thus concluded that the presence of FA in a reacting medium enhances fluorescence formation, such that δF be can used as an accurate measure of fish damage. It is thought that measurement of δF in processes such as the freezing of gadoid fish, in which both FA and lipid oxidation are produced, could be of benefit. Received: 23 June 1997     

Swallowing of hydrochloric acid: study of 25 cases

INTRODUCTION: Ingestion of hydrochloric acid solutions (Salfumant/Salfuman) constitute a relatively frequent emergency in our environment. It is a strong acid, highly corrosive, the swallowing of which causes a very serious necrosis of the gastrointestinal tract. AIM: We review our experience on emergency treatment of inpatients after the swallowing of watery hydrochloric acid solutions, in order to identify the most important prognosis factor. PATIENTS AND METHODS: During the last thirteen years, 25 patients have been attended in our center with the diagnosis of hydrochloric acid swallowing. The clinical and therapeutical characteristics are respectively analyzed, as well as the high morbi-mortality of these kind of emergencies. RESULTS: Global mortality of the series has been 48% (12 patients). The common characteristic of these 12 patients was the esophagogastric massive necrosis, and the duodenopancreatic frame necrosis. Ten patients who did not present duodenal necrosis or were operated on of later complications, survived. Three patients could be managed with medical conservative treatment. CONCLUSIONS: Hydrochloric acid swallowing constitutes an extraordinary severe emergency, with a high mortality, mainly related to necrosis extension to the duodenopancreatic frame.     

Molecular epidemiology of HIV-1 infection in the Philippines, 1985 to 1997: transmission of subtypes B and E and potential emergence of subtypes C and F

OBJECTIVES: to identify the risk factors for hepatitis B (HBV) and hepatitis C (HCV) virus infections in drug users attending two drug treatment centres in Northwest England, and to evaluate the effect of both needle exchange and hepatitis B vaccination on the prevalence of hepatitis B and hepatitis C infections. METHODS: a retrospective, cross-sectional study performed at the Regional Infectious Disease Unit and a Primary Care Centre for drug users in Liverpool. The study population included 773 drug users who had hepatitis serology performed between January 1992 and April 1996. Information on risk factors was obtained from clinical records; hepatitis serology data were obtained from the Liverpool Public Health Laboratory database. RESULTS: the overall seroprevalences of exposure markers for HBV (anti-HBc antibody) and HCV (anti-HCV antibody) were 48% and 67%, respectively. Duration of injecting drug use was the strongest predictor of HCV infection, with a crude odds ratio of 8.9 (95% confidence interval (CI): 4.5-17) for >10 compared to <3 years of injecting, and was also a strong predictor of HBV infection, with an adjusted odds ratio (controlled for the effects of HBV vaccination) of 5.7 (95% CI: 3.2-10) for >10 compared to <3 years' injecting. Vaccination against HBV was associated with greatly reduced HBV seroprevalence (crude odds ratio 0.11, 95% CI: 0.06-0.18). Overall, HCV was acquired earlier in the injecting career than HBV, but drug users who were not vaccinated against HBV acquired markers for HBV even more rapidly than for HCV. We found no independent protective effect for either anti-HBc or anti-HCV acquisition after the introduction of a needle-exchange scheme. CONCLUSIONS: hepatitis C is highly prevalent among Merseyside drug users and is likely to prove difficult to control because of rapid acquisition early in the injecting career. Vaccination against hepatitis B is the best means of protecting drug users from hepatitis B, and should be offered before injecting is commenced.