Current-switching half adder

A new current-switching half adder is described; rise and fall times of about 3 ns have been obtained.     

Liver injury in abdominal trauma. Review of the literature and personal observations

The association of infantile diarrhoea with the occurrence of Candida species and their different morphological cell forms (pseudohyphae and/or blastospores) in faeces was studied in children of 0-15 months in a developing community (Lahore, Pakistan) where malnutrition is prevalent. Stool samples from 119 patients admitted to the Diarrhoea Treatment Unit, Department of Pediatrics, King Edward Medical College, and 46 healthy children were investigated for yeasts, bacteria, viruses and parasites. Salmonella and enteropathogenic Escherichia coli were seen in 13 (11%) each of the cases while Candida was the most frequent micro-organism, grown in cultures from 38 (32%) of the diarrhoea cases. C. tropicalis dominated (19%) over C. albicans (6%) and C. parapsilosis (3%). However, in a great number of cases (23, equals 19%), Candida did not grow in cultures but blastospores and/or pseudohyphae were seen on microscopical examination. Other Candida species and yeasts were relatively more common in the control group. Candida albicans, C. tropicalis and C. parapsilosis were the only identified agents in 23 of the cases (19%). The characteristic clinical findings in children with Candida as the only identified pathogen were malnutrition (69%), age less than 8 months (90%), and microscopically identified pseudohyphae in faecal smears (71%).     

Fiber-optical measurement of form deviations of rotation-symmetric parts

The quality inspection of products poses a challenge towards existing production metrology techniques in terms of accuracy and speed, especially when it comes to inline or in-process measurements. In this terms, optical metrology proves its capabilities, in particular for sensible and fragile work pieces. For the inspection inside small spaces and cavities or for complex geometries, many optical metrology system are to inflexible or cannot be miniaturized enough. Within this work a set-up for a fiber-optic low-coherence interferometer system is described. Due to the high degree of miniaturization of the sensing probe, the system can be used for demanding measuring tasks like roundness of small drilling holes or the run-out of shafts. Different evaluation measurement are presented, which underline the potential of the described system for highly accurate, non-contact inspection of rotational parts.     

In situ Spinel Expansion Design by Colloidal Alumina Suspension Addition

The incorporation of nano powders into refractory castables it is not a straightforward procedure, due to their agglomeration and sintering drawbacks. Considering the alumina grain size effect on the in situ spinel formation and the associated overall volumetric expansion, alumina–magnesia refractory castables containing different alumina sources were evaluated by the assisted sintering technique. Reducing the size of fine tabular alumina (<200 μm) led to lower expansion levels, indicating the main role of alumina grain size in this property. Regarding the reactive aluminas (nano alumina powder, hydratable alumina, and colloidal alumina), the composition containing colloidal alumina performed remarkably better, leading to the lowest in situ spinel expansion level as a consequence of its high sinterability. The use of nano scaled alumina suspensions was the most suitable alternative to inhibit the shortcoming of nano powder agglomeration. Conversely, the castable containing the nano alumina powder did not behave as expected. The present work pointed out that the use of nano powders in refractory castables is only feasible if the compound is fully dispersed. Otherwise, cheaper raw materials could provide even better results than those of nano agglomerated powders.     

Ultrafine grinding of sugar cane bagasse ash for application as pozzolanic admixture in concrete

Sugar cane bagasse ash, a byproduct of sugar and alcohol production, is a potential pozzolanic material. However, its effective application in mortar and concrete requires first the controlled use of grinding and classification processes to allow it to achieve the fineness and homogeneity that are required to meet industry standards. The present paper investigates the role of mill type and grinding circuit configuration in grinding in laboratory- and pilot plant-scale on the particle size, specific surface area and pozzolanic activity of the produced ashes. It was observed that, although different size distributions were produced by the different mills and milling configurations, the pozzolanic activity of the ground ash was directly correlated to its fineness, characterized by its 80% passing size or Blaine specific surface area. From a low pozzolanic activity of less than 50% of the as-received ash, values above 100% could be reached after prolonged grinding times. Electric power requirements to reach the minimum pozzolanic activity were estimated to be in the order of 42 kWh/t in an industrial ball mill. Incorporation of an ultrafinely-ground ash in a high-performance concrete in partial replacement of Portland cement (10, 15 and 20% by mass) resulted in no measurable change in mechanical behavior, but improved rheology and resistance to penetration of chloride ions.     

Changes in the non-protein thiol pool and production of dissolved gaseous mercury in the marine diatom Thalassiosira weissflogii under mercury exposure

Two detoxification mechanisms working in the marine diatom Thalassiosira weissflogii to cope with mercury toxicity were investigated. Initially, the effect of mercury on the intracellular pool of non-protein thiols was studied in exponentially growing cultures exposed to sub-toxic HgCl₂ concentrations. T. weissflogii cells responded by synthesizing metal-binding peptides, named phytochelatins (PCs), besides increasing the intracellular pool of glutathione and γ-glutamylcysteine (γ-EC). Intracellular Hg and PC concentrations increased with the Hg concentration in the culture medium, exhibiting a distinct dose-response relationship. However, considerations of the PCs-SH:Hg molar ratio suggest that glutathione could also be involved in the intracellular mercury sequestration. The time course of the non-protein thiol pool and Hg intracellular concentration shows that PCs, glutathione and γ-EC represent a rapid cellular response to mercury, although their role in Hg detoxification seems to lose importance at longer incubation times. The occurrence of a process of reduction of Hg(II) to Hg° and subsequent production of dissolved gaseous mercury (DGM) was also investigated at lower Hg concentrations, at which the PC synthesis doesn't seem to be involved. The significant (P < 0.01) correlation between the cellular density in solution and the production of DGM suggests that this diatom is capable of directly producing DGM, both in light and dark conditions. This finding has been confirmed by the absence of DGM production in the culture media containing formaldehyde-killed cells. Finally, the relationship between these two different pathways of Hg detoxification is discussed.     

Aerobic Training in Young Men Increases the Transfer of Cholesterol to High Density Lipoprotein In Vitro: Impact of High Density Lipoprotein Size

Exercise training not only improves the plasma lipid profile but also reduces risk of developing coronary heart disease. We investigate whether plasma lipids and high density lipoprotein (HDL) metabolism are affected by aerobic training and whether the high-density lipoprotein cholesterol (HDL-C) levels at baseline influence exercise-induced changes in HDL. Seventy-one male sedentary volunteers were evaluated and allocated in two subgroups, according to the HLD-C levels (< or >40 mg/dL). Participants underwent an 18-week aerobic training period. Blood was sampled before and after training for biochemical analysis. Plasma lipids, apolipoproteins, HDL diameter, and VO₂ peak were determined. Lipid transfers to HDL were determined in vitro by incubating plasma samples with a donor lipid artificial nanoemulsion. After the 18-week period of aerobic training, the VO₂ peak increased, while the mean body mass index (BMI) decreased. HDL-C concentration was higher after the training period, but low-density lipoprotein cholesterol (LDL-C) and non-HDL-C did not change. The transfer of esterified cholesterol and phospholipids was greater after exercise training, but the triacylglycerol and unesterified cholesterol transfers were unchanged. The HDL particle diameter increased after aerobic training in all participants. When the participants were separated in low-HDL and normal-HDL groups, the postaerobic exercise increment in HDL-C was higher in the low-HDL group, while the transfer of esterified cholesterol was lower. In conclusion, aerobic exercise training increases the lipid transfers to HDL, as measured by an in vitro method, which possibly contributes to the classical elevation of the HDL-C associated with training.     

A Relationship Between the Heat of Vaporization,Surface Tension,and the Solubility Parameters,Which Includes the Ratio of the Coordination Numbers,Based on Stefan's Rule

The correct calculi of surface tension and solubility parameters are of paramount importance for many fields of chemical engineering and materials design, such as encapsulation methods (which use the mean field theory), dispersion of nanopowders, phase compatibility in chemical blends and nanocomposites, among others. The solubility parameters play a key role in these applications along with the surface tension. Until now, the relationship between solubility parameters and surface tension was only indirect, through the Skaarup–Beerbower formula, although well‐known physicochemical rules, such as Stefan's rule, could be applied to them directly, as shown in this study. The prediction of both the solubility parameters and surface tension within chemical groups can be obtained with high accuracy using critical temperature and molar volume, parameters easily found in the literature. The proposed rules are original, simple and have direct practical applications for the development of new materials. POLYM. ENG. SCI., 59:E312–E321, 2019. © 2018 Society of Plastics Engineers     

Chitosan and cyanoguanidine-crosslinked chitosan coated glass beads and its application in fixed bed adsorption

Abstract

The aim of this work was to coat glass beads with chitosan and cyanoguanidine-crosslinked chitosan and, afterward, to verify the potential of the coated beads as adsorbent for the FD&C Red 40 dye in fixed bed column. The coating was realized in eight experimental conditions, varying the technique (dip coating or casting) and the coating solution composition (different proportions of chitosan, cyanoguanidine, glycerol, sorbitol, sodium alginate, NaOH and CaCl₂). The beads coated in the eight experimental conditions were then applied to adsorb FD&C Red 40 in a fixed bed column, from aqueous solutions at pH 3.0 and 6.0. The breakthrough curves were fitted according to Thomas and Yoon-Nelson dynamic models. The coating was dependent of the solution composition. The casting technique presented coating percentage values of 92%, while the dip coating technique presented only 43%. The breakthrough curves revealed that the use of glass beads coated with cyanoguanidine-crosslinked chitosan had good performance, attaining adsorption capacity values higher than 80?mg g^?1. Thomas and Yoon-Nelson models were able to predict the breakthrough curves in all conditions.