用近红外光谱分析转基因抗虫棉根际全氮和有机质含量

随着转基因植物的普及推广,人们越来越关心其生态安全性。以转基因棉花及其对照为实验材料,借助于近红外光谱仪对转基因棉花及其对照根际土壤和非根际土壤中的全氮和有机质进行了分析测定,扫描区间为12 000～4 000 cm-1,分辨率为4 cm-1,扫描次数为64次;同时用标准方法进行对比测定。结果显示近红外检测样品的结果与标准方法结果无明显差别,说明通过扫描光谱加上数学和计算机软件分析,非常准确、方便地测定了转基因作物根际土壤中的全氮和有机质。结果显示,转基因棉花根际土壤中的全氮和有机质含量显著高于对照中的含量,分析原因主要可能与转基因抗虫棉向根际土壤分泌毒蛋白所致,毒蛋白会结合在土壤颗粒上,降解较慢,增加了全氮和有机质的含量,有机质又会增加土壤微生物的繁殖,进一步增加了土壤有机质含量。     

Thermal dissociation of ions limits the degree of the gas‐phase H/D exchange at the atmospheric pressure

We present the application of the extended desolvating capillaries for increasing the degree of the gas‐phase hydrogen/deuterium exchange reaction at atmospheric pressure. The use of the extended capillaries results in the increase of the time that ions spend in the high pressure region, what leads to the significant improvement of the efficiency of the reaction. For the small protein ubiquitin, it was observed that for the same temperature, the number of exchanges increases with the decrease of the charge state so that the lowest charge state can exchange twice the number of hydrogen than the highest one. With the increase of the temperature, the difference decreases, and eventually, the number of exchanges equalizes for all charge states. The value of this temperature and the corresponding number of exchanges depend on the geometric parameters of the capillary. Further increase of the temperature leads to the thermal dissociation of the protein ion. The observed b/y fragments are identical to those produced by collision‐induced dissociation performed in the ion trap. Copyright © 2017 John Wiley & Sons, Ltd.     

Supersymmetry status and phenomenology at the Large Hadron Collider

Large Hadron Collider (LHC) has a great chance to finally reveal supersymmetry which remains a compelling theory for over 30 years in spite of lack of its discovery. It might be around the corner the present LHC era with sensitive dark matter search experiments and international linear collider hopefully coming up in the near future.      

Inter-particle interaction induced by broadband radiation

The recent fabrication of optical traps using super-continuum light impresses the need for a theory of inter-particle interactions under such conditions. Development of the theory provides a basis for calculation of the observations expected under experimental conditions. An expression for the inter-particle potential energy induced by continuum states of light is first derived using quantum electrodynamics. This energy expression is cast as a function of the spectral irradiance of the light, and the electric susceptibility of the interacting particles. Specific results are derived for light with a Lorentzian spectrum. It is shown that by filtering part of the spectrum, it is possible to exert control over the length of linear particle chains organized along the Poynting vector. The results exhibit scope for the optical fabrication of moldable structures using broadband light.     

Chemical composition of PM_(2.5) during winter in Tianjin,China

PM2.5 samples for 24 h were collected during winter in Tianjin,China. The ambient mass concentration and chemical composition of the PM2.5 were determined. Ionic species were analyzed by ion chromatog-raphy,while carbonaceous species were determined with the IMPROVE thermal optical reectance(TOR) method,and inorganic elements were measured by inductively coupled plasma-atomic emission spec-trometer. The daily PM2.5 mass concentrations ranged from 48.2 to 319.2 g/m3 with an arithmetic average of 144.6 g/m3. ...     

Interaction of Short Laser Pulses in Wavelength Range from Infrared to X‐ray with Metals,Semiconductors, and Dielectrics

Laser‐matter interaction is defined by an electronic band structure of condensed matter and frequency ω_L of electromagnetic radiation. In the range of moderate fluences, the energy absorbed by electrons from radiation finally thermalizes in the ion thermal energy. The thermalization processes are different for optical as compared with X‐ray quanta and for metals relative to semiconductors and dielectrics, since the light absorption and electron‐electron, electron‐ion dynamics are sensitive to the electron population in a conduction band and the width of a forbidden gap. Although the thermalization processes are different, the final state is simply a heated matter. Laser heating creates powerful stresses in a target if duration of a laser pulse τ_L is short in acoustic time scale. Nucleation and material removal take place under such stresses. Such way of removal is called here the spallative ablation. Thus the spallative ablation is an ablation mechanism universally important for qualitatively different materials and quanta (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The use of vibrational spectroscopy to study the pathogenesis multiple sclerosis and other neurological conditions

Spectroscopy techniques are valuable tools in biomedical research and have been used extensively in the study of disease. However, neurological conditions such as multiple sclerosis (MS) have received little attention and the available spectroscopy studies are limited, both in overall numbers of patients studied and the disease samples considered. MS is a complex immune-mediated disease, with variable clinical courses and limited therapeutic options. This review aims to summarize current literature in the area, demonstrating how spectroscopy techniques can provide valuable information to inform and advance research into the most common neurological condition affecting young adults.     

The symmetric heavy-light ansatz

The symmetric heavy-light ansatz is a method for finding the ground state of any dilute unpolarized system of attractive two-component fermions. Operationally it can be viewed as a generalization of the Kohn-Sham equations in density functional theory applied to N -body density correlations. While the original Hamiltonian has an exact Z₂ symmetry, the heavy-light ansatz breaks this symmetry by skewing the mass ratio of the two components. In the limit where one component is infinitely heavy, the many-body problem can be solved in terms of single-particle orbitals. The original Z₂ symmetry is recovered by enforcing Z₂ symmetry as a constraint on N -body density correlations for the two components. For the 1D, 2D, and 3D attractive Hubbard models the method is in very good agreement with exact Lanczos calculations for few-body systems at arbitrary coupling. For the 3D attractive Hubbard model there is very good agreement with lattice Monte Carlo results for many-body systems in the limit of infinite scattering length.     

A comparison of the magnetic properties of proton- and iron-implanted graphite

In this work we have investigated the changes of the magnetic properties of highly oriented pyrolytic graphite samples after irradiation either with ~3×10¹⁴ protons or 3.5×10¹³ ... 3.5×10¹⁴ iron ions with energies in the MeV range. Our results show that iron and proton irradiations can produce similar paramagnetic contributions depending on the implantation temperature. However, only protons induce a ferromagnetic effect.     

Geometric Conditions on the Type of Matter Determining the Flat Behavior of the Rotational Curves in Galaxies

In an arbitrary axisymmetric stationary spacetime, we determine the expression for the tangential velocity of test objects following a circular stable geodesic motion in the equatorial plane, as function of the metric coefficients. Next, we impose the condition, observed in large samples of disks galaxies, that the magnitude of such tangential velocity be radii independent in the dark matter dominated region, obtaining a constraint equation among the metric coefficients, and thus arriving to an iff (iff means: if and only if.) condition: The tangential velocity of test particles is radii independent iff the metric coefficients satisfied the mentioned constraint equation. Furthermore, for the static case, the constraint equation can be easily integrated, leaving the spacetime at the equatorial plane essentially with only one independent metric coefficient. With the geometry thus fixed, we compute the Einstein tensor and equate it to an arbitrary stress energy tensor, in order to determine the type of energy-matter which could produce such a geometry. Within an approximation, we deduce a constraint equation among the components of the stress energy tensor. We test in that constraint equation several well known types of matter, which have been proposed as dark matter candidates and are able to point for possible right ones. Finally, we also present the spherically symmetric static case and apply the mentioned procedure to perfect fluid stress energy tensor, recovering the Newtonian result as well as the one obtained in the axisymmetric case. We also present arguments on the need to use GR to study types of matter different than the dust one.