The peculiarities of ultrasound wave propagation in magnetorheological fluid with complex dispersive phase

This work is devoted to experimental study of the peculiarities of ultrasound wave propagation in magnetorheological fluid (MRF) with complex disperse phase under evaluation of changing of ultrasonic waves (UW) velocity in MRF on the base of water, oxide powder and carbonyl iron particles vs. intensity of applied magnetic field have been obtained. It was found that in the result of magnetic field separation the oxide layer thickness of MRF is increasing with the field value and can be determined by 2-3 µm and lesser

Halo-substituted azobenzenes adsorbed at Ag(111) and Au(111) interfaces: Structures and optical properties

YesThe adsorption of azobenzene (AB), ortho fluoro-azobenzene (FAB) and ortho chlor-azobenzol (ClAB), in both the cis and trans isomers, at the Au(111) and Ag(111) surfaces is investigated using plane-wave density functional calculations with the revPBE-vdW-DF functional. The resulting adsorption energies and internal structures of AB adsorbed to both metal surfaces are in broad agreement with available experimental data. In the gas phase, FAB and ClAB feature a significant reduction in the energy difference between the two isomeric states, compared with AB. This relative reduction in the energy difference is still significant for the adsorbed form of FAB but is only weakly apparent for ClAB. The absorption spectra of the molecules have also been calculated, with the halogen substituents generating significant changes in the gas phase, but only a modest difference for the adsorbed molecules

Обратное рассеяние ультразвуковых волн как основа метода контроля структуры и физико-механических свойств чугунов

Increasing the reliability of control of cast iron structure and its physical and mechanical characteristics is an important scientific and technical task of the machine-building industry. The paper studies the possibilities of controlling the structure of cast irons using structural noise created by ultrasonic scattering on graphite inclusions of different shapes. The subject of the present studies was such characteristics of structural noise as amplitude-temporal A(t) and as root mean square value of the amplitude of the ultrasonic waves backscattering field AN, compared with the data on ultrasonic velocity and strength or tensile strength of cast iron samples. As a result of the studies, a significant difference between the amplitude parameters of the AN structural noise obtained for samples with different shapes of graphite inclusions at 5 MHz was revealed for the first time. So, for example, for samples of gray cast iron (Russian: СЧ10, СЧ15, СЧ20, СЧ25), having predominantly plate-like form of graphite inclusions, the value of AN on 14–15 dB exceeds that measured in high-strength specimens of the cast iron with the prevailing form of spherical graphite inclusions ВЧ50 (Russian), etc. At the same time growth of longitudinal ultrasonic velocity amounted to 20–25 %. The method of rejection of gray cast iron from high-strength cast iron according to the data of amplitude parameters of structural noise AN at unilateral and local sounding of the object without using an additional reference signal reflected from its oppositional wall is suggested.Повышение надёжности контроля структуры чугунов и их физико-механических характеристик является важной научно-технической задачей машиностроительной промышленности. В работе изучены возможности контроля структуры чугунов, используя структурный шум, создаваемый рассеянием ультразвуковых колебаний на графитовых включениях разной формы. Предметом настоящих исследований являлись такие характеристики структурного шума как амплитудновременные А(t) и среднеквадратичные амплитуды AN волн рассеяния, сопоставляемые с данными по скорости ультразвуковых колебаний, а также прочностью или временным сопротивлением на растяжение образцов чугунов. В результате исследований впервые выявлено существенное различие между амплитудными параметрами структурного шума AN, полученными для образцов с разной формой графитовых включений на частоте 5 МГц. Так, например, для образцов серого чугуна (СЧ10, СЧ15, СЧ20, СЧ25), имеющих преимущественно пластинчатую форму графитовых включений, величина AN на 14–15 дБ превышает ту, что измерена в высокопрочных чугунах с превалирующей формой включений графита шаровидной формы – ВЧ50. При этом, рост продольной скорости ультразвука с увеличением временного сопротивления составил ≈ 20–25 %. Предложен метод отбраковки серого чугуна от высокопрочного по данным амплитудных параметров структурного шума AN при одностороннем и локальном прозвучивании объекта без использования дополнительного опорного сигнала, отражённого от его оппозитной стенки

Backscattering of Ultrasonic Waves as the Basis of the Method of Control of Structure and Physicо-Mechanical Properties of Cast Irons

Increasing the reliability of control of cast iron structure and its physical and mechanical characteristics is an important scientific and technical task of the machine-building industry. The paper studies the possibilities of controlling the structure of cast irons using structural noise created by ultrasonic scattering on graphite inclusions of different shapes. The subject of the present studies was such characteristics of structural noise as amplitude-temporal A(t) and as root mean square value of the amplitude of the ultrasonic waves backscattering field AN, compared with the data on ultrasonic velocity and strength or tensile strength of cast iron samples. As a result of the studies, a significant difference between the amplitude parameters of the AN structural noise obtained for samples with different shapes of graphite inclusions at 5 MHz was revealed for the first time. So, for example, for samples of gray cast iron (Russian: СЧ10, СЧ15, СЧ20, СЧ25), having predominantly plate-like form of graphite inclusions, the value of AN on 14–15 dB exceeds that measured in high-strength specimens of the cast iron with the prevailing form of spherical graphite inclusions ВЧ50 (Russian), etc. At the same time growth of longitudinal ultrasonic velocity amounted to 20–25 %. The method of rejection of gray cast iron from high-strength cast iron according to the data of amplitude parameters of structural noise AN at unilateral and local sounding of the object without using an additional reference signal reflected from its oppositional wall is suggested

Кислотно-основные свойства поверхности оксида хрома(III)

The article is devoted to the study of the nature and number of acid-base centers on the surface of chromium(III) oxide obtained by precipitation from an aqueous nitrate solution. The curve of the distribution of the number of acidbase centers of the samples is plotted depending on the indicator of the ionization constant of indicators. It was determined that the main Lewis centers make the main contribution to the acidity of the samples; there are also Bronsted centers of different acidity. A comparative analysis of the structural features of the surface of oxides of chromium, zinc and binary systems Cr (III)–Zn (II) was carried out according to the results of X-ray phase analysis of oxides and thermolysis of the corresponding hydroxides. Based on this, the possibility of obtaining nanosized catalysts based on oxide-hydroxide systems of chromium with a number of 3d-metals obtained in the process of polynuclear hydroxocomplexation is predicted.Проведено исследование природы и количества кислотно-основных центров на поверхности оксида хрома(III), полученного осаждением из водного нитратного раствора. Определено, что основной вклад в кислотность образцов вносят основные центры Льюиса, присутствуют также различные по кислотности центры Бренстеда. Проведен анализ структурных особенностей поверхности оксидов хрома, цинка и двойных систем Cr(III)–Zn(II) по результатам рентгенофазового анализа оксидов и термолиза соответствующих гидроксидов. На основании этого прогнозируется возможность получения наноразмерных катализаторов на основе оксидно-гидроксидных систем хрома с рядом 3d-металлов, получаемых в процессе полиядерного гидроксокомплексообразования

Relating gene expression data on two-component systems to functional annotations in Escherichia coli

<p>Abstract</p> <p>Background</p> <p>Obtaining physiological insights from microarray experiments requires computational techniques that relate gene expression data to functional information. Traditionally, this has been done in two consecutive steps. The first step identifies important genes through clustering or statistical techniques, while the second step assigns biological functions to the identified groups. Recently, techniques have been developed that identify such relationships in a single step.</p> <p>Results</p> <p>We have developed an algorithm that relates patterns of gene expression in a set of microarray experiments to functional groups in one step. Our only assumption is that patterns co-occur frequently. The effectiveness of the algorithm is demonstrated as part of a study of regulation by two-component systems in <it>Escherichia coli</it>. The significance of the relationships between expression data and functional annotations is evaluated based on density histograms that are constructed using product similarity among expression vectors. We present a biological analysis of three of the resulting functional groups of proteins, develop hypotheses for further biological studies, and test one of these hypotheses experimentally. A comparison with other algorithms and a different data set is presented.</p> <p>Conclusion</p> <p>Our new algorithm is able to find interesting and biologically meaningful relationships, not found by other algorithms, in previously analyzed data sets. Scaling of the algorithm to large data sets can be achieved based on a theoretical model.</p

The morphofunctional and biochemical characteristics of opisthorchiasis-associated cholangiocarcinoma in a Syrian hamster model

The validity of experimental models of pathologies is one of the key challenges in translational medicine. Cholangiocarcinoma, or bile duct cancer, ranks second among oncological diseases of the liver. There is a strong association between bile duct cancer and parasitic infestation of the liver caused by trematodes in the family Opisthorchiidae. We have recently demonstrated that cholangiocarcinoma can develop in Syrian hamsters (Mesocricetus auratus) infected by Opisthorchis felineus and administered with dimethylnitrosamine. However, there is still no description of how this experimental model can possibly be used in translational research. The aim of this work was to study the morphological, functional and biochemical characteristics during cholangiocarcinoma development in Syrian hamsters infected by O. felineus and administered with dimethylnitrosamine. The experi­ment lasted 30 weeks with combined exposure to dimethylnitrosamine in drinking water at a dose of 12.5 ppm and a single injection of 50 metacercariae O. felineus. It was shown that the development of cholangiocarcinoma (18 weeks) increased the total number of basophils, eosinophils and monocytes, the relative number of granulocytes, the amount of total and direct bilirubin, and cholesterol and ALT levels, but reduced the relative number of lymphocytes. Based on pathological, morphometric and biochemical analyses, our model has characteristics similar to those in patients with opisthorchiasisassociated cholangiocarcinoma. Thus, this model can be used to test anticancer drugs, to study the mechanisms of cholangiocarcinogenesis and to search for molecular markers for early diagnosis of bile duct cancer

РАСПРОСТРАНЕНИЕ ВОЛНЫ РЭЛЕЯ В ТВЕРДЫХ ТЕЛАХ С ТЕХНОЛОГИЧЕСКИМ ВЫСТУПОМ

New distinctive features of the elastic wave excitation and propagation when the Rayleigh wave probes used have been discussed. It was principally shown that such probes can be used not only to find surface defects but to find vertically oriented defects of the low reflection ability. Experimental dependences of the coefficient transformation of Rayleigh wave into edge waves vs. radius of the fillet transition have been got. Influence of the «accompanying» transverse mode excited simultaneously with Rayleigh wave on the resulting acoustic field formation in the projection volume have been investigated. Выявлены особенности возбуждения, распространения и трансформации волны Рэлея в краевые волны на радиусном переходе прямоугольного выступа. Показана принципиальная возможность применения краевых объемных волн для контроля объектов с технологическими выступами и выявления не только поверхностных дефектов, но и дефектов со слабой отражающей способностью, расположенных в объеме выступа. Получены зависимости коэффициента преобразования волны Рэлея в краевые волны при прохождении поверхностной волны по радиусному переходу выступа. Установлено влияние сопутствующей поперечной волны, возбуждаемой совместно с волной Рэлея, на формируемое в объеме выступа результирующее поле.

МРТ сосудистой стенки с парамагнитным контрастным усилением в оценке терапевтического воздействия радиочастотной абляции симпатических сплетений почечных артерий при лечении резистентной артериальной гипертонии

Aim. Quantitative follow-up of the intensity of paramagnetic contrast enhancement of the aortal wall and renal arteries walls, as indicator of the pathological subinitimal and media neoangiogenesis was carried out in patients with arterial hypertension, focusing on changes after renal denervation.Material and methods. 31 patients (as old as 57.3 ± 9.8 years) with resistant hypertension comprised the study group. The average systolic/diastolic pressure obtained from 24-h monitor study was as high as 154 ± 12 / 89 ± 9 mm Hg. The MRI studies were carried out using 1.5 Т MRI Toshiba Vantage Titan scanner. After this the intravenous contrast enhancement has been carried out (with 0.5 М paramagnetic, as 0.2 ml/Kg). The radiofrequency ablation (RFA) desympathising the kidneys was performed on X-ray operating room using the Symplicity system: Symplicity Flex renal ablation electrode with a 4F end electrode as thin as 1.33 mm and with length of 1.5 mm, and also automated RF voltage generator with built-in power management algorithms temperature (Medtronic, USA) were employed. The comparison group included 28 people who were referred for MRI study of lumbar spine (average age - 53.2 ± 17.8), without any evidence that could be attributed to the pathology of the cardiovascular system.Results. Enhancement index (EI) of the aortic wall of patients with hypertension (1.57) was significantly over the aortic EI of healthy people (1.23), p &lt; 0.0001, reflecting inflammatory neoangiogenetic changes in the vascular wall in hypertension. The correlation between EI in the wall of both renal arteries is highly reliable and linear, which confirms the idea of the systemic nature of neoangiogenesis in hypertension. Analysis of data from an MRI study of the renal arteries showed that the intensity of the accumulation of the contrast agent in their wall after RD, as a rule, decreases (the right RA distal segment 1.78, 1.61, 1.59 - at baseline, at 6 and 12 months after RD, respectively (p &lt; 0.05). Thus, a visual MRI proves electro-induced damage to the wall of the renal artery and the development of fibrosis at the site of radiofrequency exposure. At the same time, there are no significant differences in EI between studies at the sixth (p = 0.56) and twelfth (p = 0.48) months of observation after RFA, which argues in favor of maintaining fibrosis and, respectively, the absence of reinnervation and inflammatory neoangiogenesis of the arterial wall.Conclusion. MR-tomographic examination of the aorta and renal arteries with contrast enhancement should be carried out to assess the state of the walls of these vessels and to dynamically monitor their condition after renal denervation.Цель исследования: количественная оценка интенсивности контрастного усиления стенки аорты и почечных артерий как показателя протекающего патологического неоангиогенеза у пациентов с артериальной гипертонией (АГ) с оценкой его изменений после ренальной денервации.Материал и методы. Обследован 31 пациент с резистентной АГ, средний возраст 57,3 ± 9,8 года. СМАД 154 ± 12 / 89 ± 9 мм рт.ст. МРТ-исследование проводилось на МР-томографе 1,5 Тл. Протокол включал стандартные режимы для исследования сердца и грудной аорты. Контрастное усиление: внутривенно медленно 0,5 М парамагнитного контрастного препарата (0,2 мл/кг массы тела). Ренальная симпатическая денервация выполнялась в рентгеноперационных с использованием лицензированного оборудования системы Symplicity (Medtronic, США). Группа сравнения - 28 человек, проходивших амбулаторно МРТ поясничного отдела позвоночника (средний возраст 53,2 ± 17,8 года), без жалоб, которые можно было бы отнести к патологии сердечно-сосудистой системы.Результаты. Индекс усиления (ИУ) стенки аорты больных с АГ (1,57) достоверно отличается от ИУ аорты здоровых людей (1,23), p &lt; 0,0001, что отражает воспалительно-неоангиогенетические изменения в сосудистой стенке при АГ. Корреляция между показателями ИУ стенки почечных артерий высокодостоверна и линейна, что подтверждает представление о системном характере неоангиогенеза при АГ. В результате анализа данных, полученных при МРТ почечных артерий, оказалось, что при контрастировании интенсивность МРТ-сигнала от их стенок, как правило, уменьшается (правая почечная артерия дистальный сегмент 1,78, 1,61, 1,59 - исходно, в 6 и 12 мес после ренальной денервации соответственно, p &lt; 0,05). Таким образом, визуально МРТ доказывает электроиндуцированное повреждение стенки почечной артерии и развитие фиброза в месте радиочастотного воздействия. При этом нет достоверных различий в ИУ между исследованиями на 6-м (р = 0,56) и 12-м (р = 0,48) месяце наблюдения после РЧА, что свидетельствует в пользу сохранения фиброза и соответственно отсутствия реиннервации и воспалительного неоангиогенеза артериальной стенки.Заключение. МРТ-исследование аорты и почечных артерий с контрастным усилением рекомендуется проводить как диагностическую процедуру, позволяющую оценить состояние стенки данных сосудов, а также для динамического наблюдения за их состоянием после ренальной симпатической денервации