EVALUATION OF CORROSION PROPERTIES FOR USE OF AZ31B IN BIOABSORBABLE STENTS AND IN VIVO CORROSION RATE PREDICTION USING FEA

AZ31B was heat treated to evoke more controlled and uniform corrosion. 1/16” diameter AZ31B wire was cut into six samples each 1” long. The samples underwent heat treatments following ASTM B661-06. Samples were weighed and placed into three different in vitro environments. In the first scenario two samples of each heat treatment were individually placed in 50 ml of saline solution at 0.9% sodium, in a static test tube at 37°C temperature. Two samples were placed in 100 ml of 0.9% saline solution in a 250 ml stirring beaker with an average whirlpool depth of 1”. Two of each sample was placed into 50 ml of saline solution at 0.9% sodium at room temperature. The final experiment placed an air cooled sample in 0.9% saline solution in a 6mm tube with a flow rate of 325ml/min at 37°C. All samples were removed at a 3 day, dried, and weighed. Mass loss was recorded, and samples were returned to solution. Samples ranged from 32% mass loss in quenched samples to 17% mass loss in the control samples (as manufactured) over fifteen days. All samples failed as possible stent candidate materials do to the unpredictability of their corrosion in both rate and uniformity. Experimental data was used to create a theoretical mathematic model and COMSOL FEA model that synthesized experimental data and physiological effects such as wall shear stress to predict the corrosion rate for future testing as well as stent geometry optimization to promote vascular health and limit the restenosis event

Метод вдосконалення оптичних координаторів з використанням позиційно-чутливих матриць

The analysis of existing matrixes of photosensitive elements is carried out; new types of such matrixes and ways of definition of angular co-ordinates in the optical coordinators constructed on their basis are exampled; it is offered mathematical model and design procedures of characteristics of the offered schemes of photosensitive matrixes.Проведен анализ существующих матриц фоточувствительных элементов; приведены новые типы таких матриц и способы определения угловых координат в оптических координаторах, построенных на их основе; предложено математическую модель и методики расчета характеристик предложенных схем фоточувствительных матриц.Здійснено аналіз існуючих матриць фоточутливих елементів; наведені нові типи матриць і способи визначення кутових координат у оптичних координаторах, побудованих на їх основі; запропоновано математичну модель та методики розрахунку характеристик запропонованих схем фоточутливих матриць

About dihalks of Chersonesos of the second half of the IV century B.C.

At the turn of the first and second half of the IV century BC, qualitative changes in the development of the polis, associated with the arrival of new colonists, are taking place in Chersonesos. This circumstance also determines the transformations that have occurred in numismatics in this period, which the author of the article considers on the example of lower denominations – dihalks coin types

Аналіз поляризаційного фільтра з тонких круглих паралельних проводів

Abstract.Transmission coefficient of plane electromagnetic wave through a metal grid formed by thin parallel round–shaped wires arranged on a flat surface is performed. For results comparing calculations performed with the use of the analytical expressions and application packages HFSS and MWS. For comparison of theoretical calculations with experimental one the experimental setup is created and experimental studies is conducted. The theoretical calculations is confirmed experimentally. Conclusions. For practical cases to calculate transmission coefficient of polarizing filter the simplified analytical expression can be used.Проведенные расчеты коэффициента прохождения плоской электромагнитной волны через металлическую сетку, сформированную тонкими круглыми проводниками, расположенными параллельно на плоской поверхности. Для сравнения результатов, расчеты проведены с использованием аналитических выражений и пакетов прикладных программ HFSS и MWS. Для сравнения теоретических расчетов с экспериментом создан экспериментальный стенд и проведены экспериментальные исследования. Теоретические расчеты подтверждены экспериментально.Проведені розрахунки коефіцієнта проходження плоскої електромагнітної хвилі через металеву сітку, сформовану тонкими круглими провідниками, розташованими паралельно на плоскій поверхні. Для порівняння результатів, розрахунки проведені з використанням аналітичних виразів та пакетів прикладних програм HFSS і MWS. Для порівняння теоретичних розрахунків з експериментом створено експериментальний стенд і проведені експериментальні дослідження. Теоретичні розрахунки підтверджені експериментально

Анализ поляризационного фильтра из тонких круглых паралельных проводов

Проведені розрахунки коефіцієнта проходження плоскої електромагнітної хвилі через металеву сітку, сформовану тонкими круглими провідниками, розташованими паралельно на плоскій поверхні. Для порівняння результатів, розрахунки проведені з використанням аналітичних виразів та пакетів прикладних програм HFSS і MWS. Для порівняння теоретичних розрахунків з експериментом створено експериментальний стенд і проведені експериментальні дослідження. Теоретичні розрахунки підтверджені експериментально.Abstract. Transmission coefficient of plane electromagnetic wave through a metal grid formed by thin parallel round-shaped wires arranged on a flat surface is performed. The comparing of calculations with the use of the analytical expressions and application packages HFSS and MWS is performed. The experimental setup is created and experimental studies are conducted for comparison of theoretical calculations with experimental one. The theoretical calculations are confirmed experimentally. Conclusions. The simplified analytical expression can be used for practical cases to calculate transmission coefficient of polarizing filter.Проведенные расчеты коэффициента прохождения плоской электромагнитной волны через металлическую сетку, сформированную тонкими круглыми проводниками, расположенными параллельно на плоской поверхности. Для сравнения результатов, расчеты проведены с использованием аналитических выражений и пакетов прикладных программ HFSS и MWS. Для сравнения теоретических расчетов с экспериментом создан экспериментальный стенд и проведены экспериментальные исследования. Теоретические расчеты подтверждены экспериментально

Interactions between Lactobacillus crispatus and bacterial vaginosis (BV)-Associated bacterial species in initial attachment and biofilm formation

Certain anaerobic bacterial species tend to predominate the vaginal flora during bacterial vaginosis (BV), with Gardnerella vaginalis being the most common. However, the exact role of G. vaginalis in BV has not yet been determined. The main goal of this study was to test the hypothesis that G. vaginalis is an early colonizer, paving the way for intermediate (e.g., Fusobacterium nucleatum) and late colonizers (e.g., Prevotella bivia). Theoretically, in order to function as an early colonizer, species would need to be able to adhere to vaginal epithelium, even in the presence of vaginal lactobacilli. Therefore, we quantified adherence of G. vaginalis and other BV-associated bacteria to an inert surface pre-coated with Lactobacillus crispatus using a new Peptide Nucleic Acid (PNA) Fluorescence In Situ Hybridization (FISH) methodology. We found that G. vaginalis had the greatest capacity to adhere in the presence of L. crispatus. Theoretically, an early colonizer would contribute to the adherence and/or growth of additional species, so we next quantified the effect of G. vaginalis biofilms on the adherence and growth of other BV-associated species by quantitative Polymerase Chain Reaction (qPCR) technique. Interestingly, G. vaginalis derived a growth benefit from the addition of a second species, regardless of the species. Conversely, G. vaginalis biofilms enhanced the growth of P. bivia, and to a minor extent of F. nucleatum. These results contribute to our understanding of BV biofilm formation and the progression of the disorder.This work was supported by European Union funds (FEDER/COMPETE) and by national funds (FCT) under the project with reference FCOMP-01-0124-FEDER-008991 (PTDC/BIA-MIC/098228/2008) and in part by funds from the National Institutes of Health (P60-MD002256). AM acknowledges the FCT individual fellowship SFRH/BD/62375/2009

Multiphase high frequency appa-ratus for disinfestation and drying of grain

Виконано аналіз розподілу напруженості електричного поля всередині простору, обмеженого багатозв'язною кільцевою границею на основі теорії інтегральних сингулярних рівнянь у вигляді задачі спряження. Наведено розрахункові формули для визначення напруженості електричного поля в активній зоні. Запропоновані структурна схема генератора для живлення електродів та принцип побудови установки для опромінення зерна та інших сипучих матеріалів електричним полем високої частоти.Introduction. In order to reduce the field inhomogeneity caused by edge effects and capacitance of two parallel metal plate electrode system we have proposed a mathematical model of conductive multilectrode cylindrical system. Analytical analysis techniques. According to the model the analysis of the distribution of the electric field inside the zone restricted with multiply connected circular boundary on the basis of the theory of singular integral equations in the form of conjugation problem is performed. The calculation of the electric field distribution is reduced to the consideration of partial problem where only one electrode possesses a non-zero voltage. It is shown that providing the harmonic feeding of the electrode system consisting of identically sized equally spaced arc-shaped electrodes with voltages of the same amplitudes and phases equal to the angular position of the electrode on the circle will ensure the feasibility of the rotating and homogeneous field in the area. The expressions for determination of the electric field strength in the area are given. Results and discussion. It is shown that the size of the field homogeneity zone depends on the number of electrodes in such a way that increasing the number of elements causes the increasing of the zone size, and with the number of electrodes equal to 8 the diameter of the zone is equal to 60% of structure. It is proved that such an electrode system can be successfully applied for creating of apparatus for bulk materials irradiation. A schematic diagram of a generator for the electrodes supply and the principle of building of the apparatus for treat-ment of grain and other bulk materials with the electric field of high frequency are proposed.Выполнен анализ распределения напряженности электрического поля внутри пространства, ограниченного многосвязной кольцевой границей на основе теории интегральных сингулярных уравнений в виде задачи сопряжения. Приведены расчетные формулы для определения напряженности электрического поля в активной зоне. Предложены структурная схема генератора для питания электродов и принцип построения установки для облучения зерна и других сыпучих материалов электрическим полем высокой частоты

Aged-engineered nanoparticles effect on sludge anaerobic digestion performance and associated microbial communities

To investigate the potential effect of aged engineered nanoparticles (a-ENPs) on sludge digestion performance, 150 L pilot anaerobic digesters (AD) were fed with a blend of primary and waste activated sludge spiked either with a mixture of silver oxide, titanium dioxide and zinc oxide or a mixture of their equivalent bulk metal salts to achieve a target concentration of 250, 2000, and 2800 mg kg− 1 dry weight, respectively. Volatile fatty acids (VFA) were 1.2 times higher in the spiked digesters and significantly different (p = 0.05) from the control conditions. Specifically, isovaleric acid concentration was 2 times lower in the control digester compared to the spiked digesters, whereas hydrogen sulfide was 2 times lower in the ENPs spiked digester indicating inhibitory effect on sulfate reducing microorganisms. Based on the ether-linked isoprenoids concentration, the total abundance of methanogens was 1.4 times lower in the ENPs spiked digester than in the control and metal salt spiked digesters. Pyrosequencing indicated 80% decrease in abundance and diversity of methanogens in ENPs spiked digester compared to the control digester. Methanosarcina acetivorans and Methanosarcina barkeri were identified as nano-tolerant as their relative abundance increased by a factor of 6 and 11, respectively, compared to the other digesters. The results further provide compelling evidence on the resilience of Fusobacteria, Actinobacteria and the Trojan horse-like effect of ENPs which offered a competitive advantage to some organisms while reducing microbial abundance and diversity

Bacterial vaginosis biofilms: challenges to current therapies and emerging solutions

Bacterial vaginosis (BV) is the most common genital tract infection in women during their reproductive years and it has been associated with serious health complications, such as preterm delivery and acquisition or transmission of several sexually transmitted agents. BV is characterized by a reduction of beneficial lactobacilli and a significant increase in number of anaerobic bacteria, including Gardnerella vaginalis, Atopobium vaginae, Mobiluncus spp., Bacteroides spp. and Prevotella spp.. Being polymicrobial in nature, BV etiology remains unclear. However, it is certain that BV involves the presence of a thick vaginal multi-species biofilm, where G. vaginalis is the predominant species. Similar to what happens in many other biofilm-related infections, standard antibiotics, like metronidazole, are unable to fully eradicate the vaginal biofilm, which can explain the high recurrence rates of BV. Furthermore, antibiotic therapy can also cause a negative impact on the healthy vaginal microflora. These issues sparked the interest in developing alternative therapeutic strategies. This review provides a quick synopsis of the currently approved and available antibiotics for BV treatment while presenting an overview of novel strategies that are being explored for the treatment of this disorder, with special focus on natural compounds that are able to overcome biofilm-associated antibiotic resistance.Research on BV biofilms in NC laboratory is supported by funding from the Fundação para a Ciência e a Tecnologia (FCT) strategic project of unit UID/BIO/04469/2013. DM and JC acknowledge the FCT fellowships SFRH/BD/87569/2012 and SFRH/BD/93963/2013 respectively. NC is an Investigador FCT

Comparison on efficiency of various techniques in treatment of waste and sewage water – A comprehensive review

AbstractIn the present scenario, environmental laws have become stringent towards health, economy and reduction of pollution. The pollution is a result of discharge of various organic and inorganic substances into the environment. The sources of pollution include domestic agricultural and industrial water. Conventional techniques such as chemical precipitation, carbon adsorption, ion exchange, evaporations and membrane processes are found to be effective in treatment of waste and sewage water. Recently, biological treatments have gained popularity to remove toxic and other harmful substances. The objective of the paper is to make comprehensive review including the performance of each technique in treatment of waste and sewage water. The research directions are also suggested based on the review