Search

Here, we present a study of superconductivity in the Ga-Ag alloy embedded into porous template with pore diameter of 10 nm. The composition was close to the eutectic point in the gallium-rich range. We measured DC and AC magnetizations for temperatures from 1.8 to 10 K and magnetic fields up to 6 T. Three superconducting transitions were found at temperatures 7.05, 6.08, and 2.65 K in contrast to the bulk counterpart. Upper critical field lines were obtained. Activation barriers were evaluated from the AC data. The temperatures of the superconducting transitions were ascribed to emergence of β- and iota-Ga and of an intermetallic different from bulk Ag3Ga2. Keywords: nanostructured Ga-Ag eutectic alloy, superconducting transitions, segregated phases, DC and AC susceptibility.

The discovery of extreme magnetoresistance (XMR) in non-magnetic materials attracted attention to the WTe2 semimetal. We have carried out studies of magnetoresistance in a tungsten ditelluride single crystal in the magnetic field range up to 14 T. Magnetoresistance increased with increasing field following a near quadratic law without saturation. The Shubnikov-de Haas oscillations were observed. Four fundamental frequencies were found in the oscillations spectrum, which correspond to two electron and two hole pockets caused by strong spin-orbit coupling.

Dissimilar joining of aluminum (AA5754) and magnesium (AZ31) alloys was investigated in the current study via resistance spot welding. A commercial pure nickel interlayer was inserted between the two base metals to prevent the formation of Al–Mg intermetallic compounds. Microstructural investigations, via SEM/EDS and XRD methods, were carried out to characterize the Mg/Ni and Al/Ni interfaces. It was found that the Al–Mg reaction was successfully prevented and continuous submicron intermetallic layers (through Al–Ni and Mg–Ni reactions) were formed at the separate interfaces. The mechanical test results indicated substantial improvement in the joint strength compared to a direct joint without using an interlayer. The application of excessively high welding current (42 kA) caused microstructure deterioration at the Mg/Ni interfacial region. Investigation of the fracture surface revealed that microstructure defects in the latter region should take responsibility for the reduction in the joint strength at high welding current (42 kA). Keywords: Resistance spot welding, Al AA5754/Mg AZ31B dissimilar welding, Interfacial reaction, Intermetallic compounds, Ni interlayer

Peroxisome proliferator activator receptor-gamma (PPARγ) is a ligand-activated transcriptional factor involved in the carcinogenesis of various cancers. Insulin-like growth factor-binding protein-3 (IGFBP-3) is a tumor suppressor gene that has anti-apoptotic activity. The purpose of this study was to investigate the anticancer mechanism of PPARγ with respect to IGFBP-3. PPARγ was overexpressed in SNU-668 gastric cancer cells using an adenovirus gene transfer system. The cells in which PPARγ was overexpressed exhibited growth inhibition, induction of apoptosis, and a significant increase in IGFBP-3 expression. We investigated the underlying molecular mechanisms of PPARγ in SNU-668 cells using an IGFBP-3 promoter/luciferase reporter system. Luciferase activity was increased up to 15-fold in PPARγ transfected cells, suggesting that PPARγ may directly interact with IGFBP-3 promoter to induce its expression. Deletion analysis of the IGFBP-3 promoter showed that luciferase activity was markedly reduced in cells without putative p53-binding sites (-Δ1755, -Δ1795). This suggests that the critical PPARγ-response region is located within the p53-binding region of the IGFBP-3 promoter. We further demonstrated an increase in PPARγ-induced luciferase activity even in cells treated with siRNA to silence p53 expression. Taken together, these data suggest that PPARγ exhibits its anticancer effect by increasing IGFBP-3 expression, and that IGFBP-3 is a significant tumor suppressor.

Food samples are collected nationwide from January 2016 to February 2017 and their contents of artificial radionuclides are measured to address the growing concerns regarding the radioactive contamination of food products in Korea. Specifically, 900 food samples are collected for this study and their contents of representative artificial radionuclides 134Cs, 137Cs, 239,240Pu, and 90Sr are analyzed. The analysis shows that the activity concentrations of 137Cs in fish range from minimum detectable activity (MDA) to 340 mBq/kg of fresh weight. The concentration factor (CF) determined for 137Cs as a measure of its bioavailability is calculated to be ca. 74 and found to be very similar to that (100) recommended by the International Atomic Energy Agency. With an MDA of

The heavy ion accelerator that will be built in Daejeon, Korea utilizes superconducting cavities operating in 2 K. The cavities are QWR (quarter wave resonator), HWR (half wave resonator), SSR1 (sing spoke resonator1) and SSR2. The main role of the cryomodule is supplying thermal insulation for cryogenic operation of the cavities and maintaining cavities' alignment. Thermal and structural consideration such as thermal load by heat leak and heat generation, cryogenic fluid management, thermal contraction, and so on. This paper describes detailed design considerations and current results have being done including thermal load estimation, cryogenic flow piping, pressure relief system, and so on.

AbstractWe study the dc magnetization of a Bi_1.94Fe_0.06Se_3 single crystal in the temperature range of 1.9 to 400 K in applied magnetic fields up to 70 kOe for two sample orientations in the applied field. We register three magnetic phase transitions and observe considerable anisotropy of the magnetic properties. The coercive force varies with temperature in a nonmonotonic manner. For the sample in a paramagnetic state, we estimate its magnetic moment per iron atom; its Curie–Weiss temperature is found to be negative. Arrot–Belov plots are constructed.

We carried out 125Te NMR studies of a WTe2 topological Weyl semimetal at temperatures of 41 and 293 K. Measurements were performed using a pulse Bruker Avance 500 NMR spectrometer. 125Te NMR spectra were obtained for the WTe2 single crystal at the orientation of the crystalline c axis parallel and perpendicular to the quantized field. We ascribed the complex spectra to four non-equivalent tellurium sites in the WTe2 crystalline structure. The recovery of the longitudinal magnetization was studied after the pulse saturation of particular lines in the spectra. We observed the single-exponential relaxation. The frequency shifts and widths of the spectral lines differed insignificantly at two temperatures while the spin-lattice relaxation times at 41 K were by a factor of approximately 30 greater than the relevant times at room temperature. Strong temperature dependence of relaxation was suggested to be due to the contribution of Weyl quasi-particles below the topological phase transition.

The formation behavior of Y 2 O 3 ceramic particles was studied by employing a very high energy ball milling (milling energy: ∼165 kJ/g·hit, milling speed: 1000 rpm). Both the XRD and HRTEM studies revealed that the high impact strain energy generated during the milling caused a drastic phase transition from the original C-type cubic (space group Ia 3, a =10.58 A) to the metastable B-type monoclinic (space group C 2/ m , a =13.89 A), finally followed by a partial solid-state amorphization. The cubic phase was difficult to be reduced down to smaller than 10 nm, while the monoclinic phase was stabilized at sizes smaller than 10 nm with a mean crystallite size of 7.57 nm. Consequently, the existence of Y 2 O 3 at a nanoscale smaller than 10 nm is possible by forming metastable monoclinic crystals, which are strain-induced.

Background Brunei Darussalam is a Sultanate with a Malay Islamic monarchy. There are high levels of dental disease among its 406,200 population. The population's oral health needs require an integrated blend of primary and specialist care, together with oral health promotion. Process and outcomes This paper describes the planning and measures taken to address these needs. In accordance with an oral health agenda published and launched in 2008, focusing on access, health promotion and prevention, and the education and training of the dental workforce, the Brunei Darussalam Ministry of Health is seeking to improve oral health status and reduce the burden of oral disease. It also seeks to transform the country's oral health services into a preventatively orientated, high-quality, seamless service underpinned by the concept of ‘teeth for life’. In the process of effecting this transition, the Brunei Darussalam Ministry of Health is developing a dental workforce fit for future purpose, with an emphasis on a modern approach to skill mix. An important element of this programme has been the development of a highly successful Brunei Darussalam Diploma in Dental Therapy and Dental Hygiene. Conclusion It is concluded that the Brunei Darussalam oral health agenda and, in particular, the forward-looking programme of dental workforce development is a model for other countries facing similar oral health challenges.

The here described proficiency test for heavy metals in compound feed was organised by RIKILT, Wageningen UR in accordance with ISO 17043. RIKILT Wageningen UR has an ISO/IEC 17043 accreditation for proficiency tests of residues in products of animal origin. However, this specific test is not part of the accreditation. The primary goal of this proficiency test was to give laboratories the opportunity to evaluate or demonstrate their competence for the analysis of heavy metals in compound feed. For this proficiency test, two test materials were dispatched. The heavy metal concentration in each material is given in mg/kg with a moisture content of 12%: • Chicken feed with a consensus value of 0.37 mg/kg cadmium and 5.2 mg/kg lead (A); • Chicken feed with a consensus value of 0.62 mg/kg cadmium and 3.0 mg/kg arsenic (B). The fortified materials were prepared by spiking a slurry of commercially obtained chicken compound feed, followed by extensive mixing and freeze-drying. Homogeneity assessment showed that all materials were sufficiently homogeneous for proficiency testing. The stability test demonstrated no statistically significant loss of cadmium, lead or arsenic from the materials during the timescale of the proficiency test. Twenty-one European laboratories participated in this proficiency test and submitted results in time. For test material A, twenty laboratories reported quantitative results and one laboratory reported a screening result for cadmium and for lead, twenty-one laboratories reported quantitative results. For test material B, twenty-one and nineteen laboratories reported quantitative results for respectively cadmium and arsenic. Two laboratories did not report quantitative results for arsenic due to the absence of the compound in their scope. Fifteen laboratories reported details of the applied extraction method. Twelve of the fifteen laboratories applied comparable digestion methods for sample preparation and in general used ICP-MS (six laboratories)

In this study, the performance of a thermo siphon type radiator made of copper for LED lighting system was evaluated by using an inverse heat transfer method. Heating experiments and finite element heat transfer analysis were conducted for three different cases. The data obtained from experiments were compared with the analysis results. Based on the data obtained from experiments, the inverse heat transfer method was used in order to evaluate the heat transfer coefficient. First, the heat transfer analysis was conducted for non-vacuum state, without the refrigerant. The evaluated heat transfer coefficient on the radiator surface was 40W/m 2 ℃. Second, the heat transfer analysis was conducted for non-vacuum state, with the refrigerant, resulting in the heat transfer coefficient of 95W/m 2 ℃. Third, the heat transfer analysis was conducted for vacuum state, with refrigerant. For the third case, the evaluated heat transfer coefficients were 140W/m 2 ℃ for the radiator body, 5W/m 2 ℃ for the rising position of radiator pipe, 35W/m 2 ℃ for the highest position of radiator pipe, and 120W/m 2 ℃ for the downturn position of radiator pipe. As a result of inverse heat transfer analysis, it was confirmed that the thermal performance of the current radiator was best in the case of the vacuum state using the refrigerant.

Although the geometry of circular cylinder is simple, the flow is complicate because of the flow separation and vortex shedding. In spite of many numerical and experimental researches, the flow around a circular cylinder has not been clarified even now. It has been known that the unsteady vortex shedding from a circular cylinder can vibrate and damage a structure. Lock-on phenomenon is very important in the flow around an oscillating circular cylinder. The lock-on phenomenon is that when the oscillation frequency of the circular cylinder is at or near the frequency of vortex shedding from a stationary cylinder, the vortex shedding synchronizes with the cylinder motion. This phenomenon can be recognized by the spectral analysis of the lift coefficient history. At the lock-on region the vortex is shedding by the modulated frequency to the body frequency. However, the vortex is shedding by the mixed frequencies of natural shedding and forced body frequency in the region of non-lock-on. In this paper, it was analyzed the relation between the frequency of rotary oscillating circular cylinder and the vortex shedding frequency.

This article presents the successful consolidation of the mixed Co and Diamond powders for a drilling segment by the combined application of magnetic pulsed compaction (MPC) and subsequent sintering, and their properties were analyzed. Homogeneous hardness (Hv 220) and density (97%) of sintered bulks fabricated by MPC were obtained by the new technique, where higher pressure has been employed for short period of time than that of general process. A fine microstructure and homogeneous hardness in the consolidated bulk were observed without cracks. Relatively higher drilling speed of 9.61 cm/min and life time of 6.55 m were found to the MPCed specimens, whereas the value of the specimens fabricated by general process was 11.71 cm/min and 7.96 m, respectively. A substantial improvement of mechanical properties of segment was achieved through this study.

The Cu oxide nano powders were synthesized by levitational gas condensation (LGC) method and their high heterogeneous catalytic effects of oxidation of 2,3,5-trimethyl-1,4-hydroquinone (TMHQ) and catalase activity were studied. The nano powders consist of mainly Cu₂O. The catalytic effect which was clarified by the oxidation of TMHQ and the activity of catalase, was found to depend on the amount of Cu₂O phase and the particle size.

Summary Hospital infection prevalence surveys were performed in our 1400-bed University medical centre in Hong Kong from 1985 to 1988. We investigated the rates of four major hospital-acquired infections (HAIs) (pneumonia, symptomatic urinary tract infection, surgical site infection and laboratory-confirmed bloodstream infection) in order to identify current distribution and any changes after 15 years. A one-day point prevalence study was performed on 7 September 2005. All inpatients were surveyed for HAIs, community-acquired infections (CAIs), risk factors, pathogenic isolates and antibiotics prescribed. Infections were diagnosed according to Centers for Disease Control and Prevention (CDC) criteria. In total, 1021 patients were surveyed; of these, 41 had 42 HAIs (4% prevalence) and 389 (38%) were receiving antibiotics. The commonest HAI was pneumonia (1.4%) followed by bloodstream infection (0.9%) and symptomatic urinary tract infection (0.8%). The prevalence of postoperative surgical site infection was 5.6%. The nosocomial prevalence rate was highest in the Intensive Care Unit, followed by the Pediatric and Neonatal Intensive Care Units, Children's Cancer Centre/Bone Marrow Transplant Unit and Orthopaedics with Traumatology. Meticillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa were the commonest pathogens. The rates are significantly lower than previously and reflect the increased resources for infection control made available following the outbreak of severe acute respiratory syndrome (SARS).

Electron paramagnetic resonance (EPR) of Fe in LiTaO single crystal, grown by Czochralski method, has been studied by employing an X-band spectrometer. Resonance spectra of Fe ion on the crystallographic principal axes were obtained with 9.447 ㎓ at room temperature. The spectroscopic splitting parameter g and zero-field splitting (ZFS) parameter D (

The dispersion stability of rutile TiO 2 powder with a unique nano-structure synthesized by homogeneous precipitation process at low temperatures (HPPLT) has been investigated with adding the various electrolytes in both pure aqueous and organic media. Zeta potential measurements have shown that the addition of electrolytes such as CsCl, CaCl 2 , FeCl 3 , and ZrCl 4 to aqueous and pure organic dispersion media leads to generally a charge reversal from negative to positive on the surface of TiO 2 particle. The electrostatic repulsive force acting on between TiO 2 particles dispersed in pure organic media was found to be significantly greater than that in aqueous media, which is closely related to the physical properties of the organic solvents, such as viscosities and dielectric constant. The surface potentials of TiO 2 particles have been greatly modified by the particulate properties, pH, dispersion medium, and valence of the ionic species, which governs the colloidal behavior of TiO 2 particles virtually.

A new fuzzy concept for postdetection signal integration is presented. The fuzzy integrator is developed as a simple extension of the classic binary integrator by replacing the crisp binary threshold, which quantizes the observed data, with a fuzzy threshold. The performance of the fuzzy integrator is illustrated for detection of a simple nonfluctuating signal in Gaussian noise and is shown to exceed that of the binary integrator, approaching that of the optimal detector with Neyman-Pearson decision rule. Furthermore, the fuzzy integrator has the characteristic that the false alarm rate can be tuned using a single threshold, more easily than that of the dual-threshold binary integrator.

Проведены исследования методом ЯМР 125Te топологического изолятора теллурида висмута Bi2Te3 в широком диапазоне от комнатной температуры до 12.5 K. Измерения проводились на импульсном ЯМР-спектрометре Bruker Avance 400. Спектры ЯМР были получены для порошка, приготовленного из монокристалла Bi2Te3, и для монокристаллических пластин в ориентациях c|| B и c normal B. Спектры при комнатной температуре состояли из двух линий, которые были отнесены к двум неэквивалентным позициями ядер теллура Te1 и Te2. Параметры тензора сдвига частоты ЯМР были найдены из спектра для порошка. Температурные зависимости спектров для порошка и пластин в ориентации c normal B согласовывались между собой. Изменения положения линий с понижением температуры объяснялись уменьшением сдвига Найта. Была оценена энергия термоактивации носителей заряда. Спектры для пластин в ориентации c|| B демонстрировали особенности ниже 91 K. Измерены времена спин-решеточной релаксации для порошка и монокристаллических пластин в обеих ориентациях при комнатной температуре. Данная работа была поддержана Российским фондом фундаментальных исследований (гранты N 14-02-92012 и 16-57-52009), ФАНО России (программа "Спин" N 01201463330), правительством Российской Федерации (государственный контракт N 02.A03.21.0006) и Национальным научным советом Тайваня. ЯМР-измерения и рентгеновская дифракция проводились в Научном парке СПбГУ. DOI: 10.21883/FTT.2017.12.45225.170

Проведены исследования методом ЯМР 125Te порошкового образца и монокристаллических пластинок топологического изолятора Bi2Te3 при комнатной температуре и при низких температурах в интервале 12.5-16.5 K. Спектры монокристаллических пластинок исследовались в ориентации, в которой кристаллографическая ось c была параллельна или перпендикулярна магнитному полю. Для получения спектров регистрировались сигналы спинового эха и строилась их огибающая. Показано, что спектр ЯМР для порошка теллурида висмута и для пластинок с ориентацией c normal B состоит из двух линий, которые предположительно обусловлены ядрами теллура в двух кристаллографических позициях в объеме образца. Положение и форма линий определяются химическим сдвигом и сдвигом Найта. Для ориентации пластинок c|| B в спектре имеется дополнительная компонента в области высоких частот, которая не может появиться за счет угловой зависимости сдвигов линий, обусловленных ядрами теллура в объеме топологического изолятора. При низкой температуре дополнительная линия доминирует в спектре. Работа выполнена при поддержке РФФИ (гранты N 14-52-12010, 16-57-52009 МНТ, 14-02-92012), в рамках государственного задания ФАНО России (тема "Спин", N 01201463330) при частичной поддержке Комплексной программы УрО РАН (проект N 15-17-2-12), правительства РФ (контракт N 02.A03.21.0006) и Национального научного совета (Тайвань, гранты N 104-2811-M-006-029 и 104-2811-M-006-031). DOI: 10.21883/FTT.2017.05.44368.370

Проведены исследования ядерной спин-решеточной релаксации и сдвига Найта ядер 71Ga, 69Ga и 115In в жидком тройном сплаве галлия, индия и олова эвтектического состава, введенном в поры опаловой матрицы и пористых стекол с размером пор 18 и 7 nm, в сравнении с объемным расплавом. Обнаружено ускорение продольной релаксации и уменьшение сдвига Найта, зависящие от размера пор. Рассчитано время корреляции атомного движения для наноструктурированного расплава в пористых матрицах. Показано, что атомная подвижность в расплаве понижается с уменьшением размера пор. DOI: 10.21883/FTT.2017.02.44062.254

Проведены измерения спектра ЯМР и восстановления продольной ядерной намагниченности после инвертирующего импульса для изотопов 69Ga и 71Ga в жидком эвтектическом сплаве Ga-In-Sn, внедренном в пористые стекла с размером пор 25 и 7 nm в сравнении с объемным расплавом в полях 9.4, 11.7 и 17.6 T. Обнаружено различие формы и положения линий ЯМР в различных полях и для разных изотопов галлия в расплаве, внедренном в пористое стекло с размером пор 7 nm. Полученные в этом образце данные интерпретированы на основе теоретической модели динамического квадрупольного сдвига, в рамках которой найдено время корреляции атомного движения. Показана согласованность характеристик атомного движения, рассчитанных на основе модели динамического сдвига и на основе измерений спиновой релаксации. Работа выполнена при поддержке РФФИ (грант N 16-57-52009). Измерения частично проводились в Ресурсном центре "Центр диагностики функциональных материалов для медицины, фармакологии и наноэлектроники" Санкт-Петербургского государственного университета. DOI: 10.21883/FTT.2017.12.45247.160

Bosonic superweakly interacting massive particles (super-WIMPs) are a candidate for warm dark matter. With the absorption of such a boson by a xenon atom these dark matter candidates would deposit an energy equivalent to their rest mass in the detector. This is the first direct detection experiment exploring the vector super-WIMPs in the mass range between 40 and 120 keV. Using 165.9 days of data no significant excess above background was observed in the fiducial mass of 41 kg. The present limit for the vector super-WIMPs excludes the possibility that such particles constitute all of dark matter. The absence of a signal also provides the most stringent direct constraint on the coupling constant of pseudoscalar super-WIMPs to electrons. The unprecedented sensitivity was achieved exploiting the low background at a level $10^{-4}$ kg$^{-1}$keV$_{ee}^{-1}$day$^{-1}$ in the detector., Comment: 12 pages, 3 figures, accepted for publication in Physical Review Letters

A total of 16 ethanol extracts of Turkish medicinal plants were evaluated for antiviral activities against herpes simplex virus (HSV) and Sindbis virus (SINV). Extracts of Galanthus elwesii and Rheum ribes showed the most potent anti-HSV activities, while six other extracts had weaker activities. Galanthus elwesii and Leucojum aestivum were the most potent anti-SINV extracts with four others showing weaker activities. In total, five extracts were active against both viruses, three were selective for HSV and one was selective for SINV. Evidence for an antiviral photosensitizer was obtained in two anti-HSV extracts, in which activity was either completely dependent on light, or was con-siderably enhanced by light. Thus, several Turkish medicinal plants appear to be promising sources of antiviral activities.