在场拭子法检测猪组织中抗生素残留

目的建立在场拭子法(swab test on premises, STOP)并对深圳市不同来源的猪肉、猪肝和猪肾抗生素残留进行筛查。方法选用枯草芽孢杆菌CMCC-63501作为实验敏感菌株,通过测定猪肉组织的加标回收率、检出限和假阴性率建立STOP法,并对市售猪组织中抗生素残留量进行筛查。结果本研究建立了乳酸环丙沙星、盐酸多西环素、恩诺沙星、硫酸新霉素、头孢噻呋钠和硫酸庆大霉素共6种敏感抗生素的标准曲线。本研究建立的STOP法的加药回收率、检出限和假阴性率均符合方法学的要求。采用STOP法对不同来源猪肉、猪肝和猪肾中抗生素残留量的筛查,结果表明,猪肝和猪肾阳性超标率分别为24%和10%,这些样本均来源于郊区,其中农贸市场的风险要高于超市,而土猪和外三元的品种之间没有明显差异。结论猪组织抗生素残留风险高发的部位、区域和场所分别是内脏、郊区和农贸市场,与猪的品种没有明显的相关性。STOP法简单快捷易操作,可适用于动物性食品中抗生素残留的现场检测。     

The application of convergent beam electron diffraction (CBED) analysis on transformation‐induced plasticity (TRIP) steels

Convergent beam electron diffraction (CBED) in transmission electron microscopy (TEM) was applied to determine local carbon concentrations in low‐carbon transformation‐induced plasticity (TRIP) steels. High‐order Laue‐zone (HOLZ) lines were experimentally obtained for comparison with simulation results. A new procedure for calculating carbon content is thus proposed. Retained austenite (RA) is classified into three types by morphology; the relationship between the carbon content and the corresponding RA morphology is discussed based on CBED results. Furthermore, results of X‐Ray diffractometry measurements are also used for comparison.     

Epigenetic Manipulation Induces the Production of Coumarin‐Type Secondary Metabolite from Arthrobotrys foliicola

Pursuing epigenetic manipulation approach in fungi led to the isolation of an unusual coumarin metabolite from fungi. An addition of the histone deacetylase inhibitor, suberohydroxamic acid (SBHA), to the culture medium of Arthrobotrys foliicola induced production of the coumarin‐type secondary metabolite represented by a single intensive peak in the HPLC profile of the ethyl acetate extract. The compound which was identified as 4‐ethyl‐7‐hydroxy‐8‐methyl‐2H‐chromen‐2‐one ( 1 ) was isolated from nature for the first time. Moreover, the investigation on the remaining part of the HPLC profile led to the separation of 6‐ethyl‐2,4‐dihydroxy‐3‐methylbenzaldehyde ( 2 ) and ten 2,5‐diketopiperazine compounds ( 3 – 12 ). The structures of isolates were deduced by their mass and NMR spectroscopic data. The coumarin‐type secondary metabolite ( 1 ) with peculiar smell induced by epigenetic stimulation is found for the first time in the Arthrobotrys species and the family Orbiliaceae. We evaluated 1 for the cytotoxic, anti‐inflammatory, anti‐allergic and nematocidal activities, however, it was found inactive.     

The effect of various fire‐exposed surface dimensions on the spalling of concrete specimens

Concrete spalling due to fire exposure is often defined as the sudden detachment of fragments from a concrete surface. It can be quantified by various parameters of which weight loss and spalling depth are the most common ones. The risk of spalling is influenced by many factors such as concrete composition, heating rate and applied testing methods. A reduced scale testing method should be developed to analyse the spalling behaviour and to understand its effectiveness in more detail. As a subsection of this development, this study aimed to analyse the effect of different‐sized, circular heated areas in semi full‐scale fire tests. Therefore, vermiculite slabs with varying cut‐outs in their centre were placed between a specimen made of a spalling‐sensitive concrete and the combustion chamber. The combustion chamber was heated following a standard fire curve. Our experimental results show that the thermal expansion inside of equal‐sized specimens is strongly dependent on the size of the heated area. In addition, this area also affects thermal stresses. They decrease as a result of lower temperature gradients for tests with smaller unheated boundary areas. Apart from this, the analysis of fragments shows no correlation between their relative volume distribution and the heated area. Copyright © 2014 John Wiley & Sons, Ltd.     

Relating video game exposure,sensation seeking,aggression and socioeconomic factors to school performance

ABSTRACT

The time displacement hypothesis has been widely used to explain the effects of media use on academic performance. This approach has been criticised for its monocausality and weak explanatory power. Utilising a combination of different theoretical perspectives is better suited than utilising only one. Considering displacement, excitement, attraction and third variable hypothesis, this paper argues that the relation between video game use and school performance is not the same for all types of gamers by considering the influence of socioeconomic, psychological and contextual factors. It investigates how gaming patterns (frequency, time of day) and psychological characteristics (sensation seeking, aggression) are related to academic performance for primary and secondary school students. Five hundred and seven students from five primary and four secondary schools in Singapore participated in a paper-pencil survey. Results showed support for a combination of displacement and third variable hypothesis, as overall time spent on video games was negatively associated with primary school children’s and active gamers’ school performances. There was no significant relationship for secondary school children. For primary school children who play games in the morning and afternoon, video game use was negatively associated with school performance. There was no support for the attraction and excitement hypotheses.     

3D printed acoustic metamaterials with microscale gaps as sound-absorbing mask for the patients of Tourette syndrome

Microsystem Technologies - Tourette syndrome (TS) is an inherited neurophysiologic disorder with onset in childhood, characterized by multiple physical (motor) tics and at least one vocal (phonic)...     

A rare case of Actinomyces skin and soft tissue infection in an end‐stage kidney disease patient with a review of the literature

End‐stage kidney disease (ESKD) patients are a commonly overlooked immunocompromised population that places them at risk for rare infections. We describe the case of a 78‐year‐old man with a history of ESKD managed with thrice weekly in‐center hemodialysis who had a prolonged episode of left elbow pain and drainage and was eventually found to have a skin and soft tissue infection from Actinomyces radingae. We review the bacteriology of Actinomyces spp. and the experiences of other providers who have treated actinomycosis in individuals with ESKD. The anatomic sites and demographics of these individuals are heterogeneous, but they all generally require a long antibiotic course with a beta‐lactam and portend to a good prognosis. High index of suspicion is needed to identify rare and atypical infections in the ESKD population.     

Depth‐Resolved Modulation of Metal–Oxygen Hybridization and Orbital Polarization across Correlated Oxide Interfaces

Interface‐induced modifications of the electronic, magnetic, and lattice degrees of freedom drive an array of novel physical properties in oxide heterostructures. Here, large changes in metal–oxygen band hybridization, as measured in the oxygen ligand hole density, are induced as a result of interfacing two isovalent correlated oxides. Using resonant X‐ray reflectivity, a superlattice of SrFeO₃ and CaFeO₃ is shown to exhibit an electronic character that spatially evolves from strongly O‐like in SrFeO₃ to strongly Fe‐like in CaFeO₃. This alternating degree of Fe electronic character is correlated with a modulation of an Fe 3d orbital polarization, giving rise to an orbital superstructure. At the SrFeO₃/CaFeO₃ interfaces, the ligand hole density and orbital polarization reconstruct in a single unit cell of CaFeO₃, demonstrating how the mismatch in these electronic parameters is accommodated at the interface. These results provide new insight into how the orbital character of electrons is altered by correlated oxide interfaces and lays out a broadly applicable approach for depth‐resolving band hybridization.