Detection of chemical warfare agents based on quantum cascade laser cavity ring-down spectroscopy

Chemical warfare agents(CWAs) are recognized as serious threats of terrorist acts against the civilian population.Minimizing the impact of these threats requires early detection of the presence of CWAs.Cavity ring-down spectroscopy(CRDS) is an exquisitely sensitive technique for the detection of trace gaseous species.In this letter,the CRDS technique is employed using a pulsed quantum cascade laser for the detection of dimethyl methylphosphonate(DMMP).A limit of DMMP detection of approximately 77 ppb is achieved.The best achievable sensitivity that corresponds to noise-equivalent absorption is approximately 2×10-7cm 1.     

Computational studies on the solvolysis of the chemical warfare agent VX

The reaction of the chemical warfare agent VX with hydroxide and hydroperoxide has been studied using a combination of correlated molecular orbital and density functional theory. It is found that the alkaline hydrolysis leads to a mixture of neurotoxic and non‐toxic products while hydroperoxidolysis leads to exclusive formation of non‐toxic products. Natural bond orbital (NBO) analysis is used to rationalize the observation that hydroxide will attack opposite the alkoxide ligand, while hydroperoxide will attack opposite the thiolate. The current results are in good agreement with previous experimental and computational work and serve to clarify the mechanism for destruction of this highly potent nerve agent. Copyright © 2008 John Wiley & Sons, Ltd.     

The laser radiation action on the biological objects

The basic physical mechanisms of laser influence on living tissues are discussed. The role of radiation monochromaticity, self-organising and non-equilibrium of laser influence, intravenous blood photomodification of and others is considered. Laser anesthesia and antistress influence is discussed. It is experimentally confirmed biological substances solution manoclusterization under the influence of laser radiation.     

Infrared dynamical thermovision of the biological objects

Dynamical infrared thermovision and applications for real time functional diagnostic of biological objects are reviewed. Experiments with humans and animals are described. It is shown that method is very promising for blood flow studies and brain research.     

Reconstructive acoustic thermotomography of biological objects

An algebraic reconstructive tomography algorithm for mapping the internal temperature field in q section of a biological object is adapted for use in a multichannel scanning acoustic thermotomograph. For some types of thermodynamic temperature distribution, using the computer simulation method, the distributions of the acoustic brightness temperature are obtained allowing for the antenna system geometry and damping in the biological medium. Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, No. 6, pp. 752–760, June, 1997.     

Near-field microwave tomography of biological objects

A method of finding the subsurface temperature distribution in biological media from near-field microwave probing data is suggested. The electrodynamic problem of probe response to a temperature profile disturbance ΔT(z) in a medium is solved. An integral equation that relates the shift of the resonant frequency of the probe to the function ΔT(z) is derived. The effective near-field probing depth is shown to depend on the probe aperture, its elevation above the surface, and the wavelength. In this method, several probes operate simultaneously, receiving signals from different depths, and the temperature profile is reconstructed by inverting the related integral equation. The components and parameters of a measuring facility that provides the temperature profi le reconstruction accurate to 0.5°C to a depth of up to 5 cm are established. The procedure of near-field diagnostics is simulated in a computer experiment to check the accuracy predicted. Calculation is performed based on a model of permittivity of biological media.     

Nanostructure materials for destruction of warfare agents and eco-toxins prepared by homogeneous hydrolysis with thioacetamide: Part 1—zinc oxide

Zinc sulphide (ZnS) nanoparticles were prepared by homogeneous hydrolysis of zinc sulphate and thioacetamide (TAA) at 80 °C. After annealing at temperature above 400 °C in oxygen atmosphere, zinc oxide (ZnO) nanoparticles were obtained. The ZnS and ZnO nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission microscopy (HRTEM), selected area electron diffraction (SAED), by BET and BJH methods used for surface area and porosity determination. The photocatalytic activity of the as-prepared ZnO samples was determined by the decomposition of Orange II in the aqueous solution under UV irradiation of 365 nm of wavelength.     

Nondestructive analyses of carbonate rocks: applications and potentiality for museum materials

The preciousness of historical artifacts leads to the performance of nondestructive and/or microdestructive analyses, especially when the archeological finds are stored in museums. The PXRF spectrometry represents a powerful technique for the chemometric study of the materials, in alternative to the more usual destructive X‐ray‐based methods. A large set of limestones belonging to several formations cropping out in the Hyblean area (south‐eastern Sicily, Italy) was analyzed by means of a PXRF instrument. The main goal was to test the PXRF potentiality for the discrimination of rocks with similar features and to create a chemical database of carbonate rocks, which were commonly used in the past in the manufacturing of sculptures and stone artifacts. Fluorescence data were processed by means of multivariate statistical analysis. In particular, principal components analysis and linear discriminant analysis were applied. The results allowed us to classify the samples belonging to different formations and to distinguish different rock typologies within each formation. Finally, the investigation showed that the analytical PXRF data can be suitable for a substantial characterization of stone materials and this could be extended to museum materials belonging to cultural heritage. Copyright © 2012 John Wiley & Sons, Ltd.     

Effect of visible light on biological objects: Physiological and pathophysiological aspects

Visible light is a necessary condition for the existence of life on the Earth. The food and oxygen consumed by humans, directly or mediately, are products of photosynthesis: conversion of light energy into the energy of chemical bonding in organic matter. Visible light not only provides photosynthesis in plants; it is also involved in the regulation of many reactions (from molecular to behavioral) in the animal world. This review is devoted to the questions concerning the role of light in the life of biological objects and the physical mechanisms of interaction of visible light with matter. The effect of light on the molecular and physiological reactions of a human and its microflora is analyzed. The existing methods and the application potential of light effects in diagnostics and therapy are considered.     

A physical model of the action of low-intensity laser radiation on biological objects

A new model of the action of low-intensity laser radiation (LILR) on biological objects on the cellular level is proposed. The model implies that, because the laser radiation is coherent, the illumination in the bulk of a biological object can acquire a spatially periodic character (in the form of an interference pattern or speckle structure), with the period of alternating dark and light regions being comparable with the size of cells or cell organelles. Under these conditions of high-gradient illumination, an electrical field can arise (the Dember effect) that can change the character of photostimulated reactions and the membrane charge state not only in the cell itself but also in its organelles, which leads to shifts in the life cycle of cells (and/or bacteria).     

Photoluminescence of nucleic bases, DNA, and biological objects

Photoluminescence spectra of nucleic bases, DNA, and two types of microorganisms, excited by the fourth harmonic radiation of the YAG:Nd³⁺ laser with a wavelength of 266 nm, were studied. It was shown that photoluminescence in these biological objects is very efficiently excited due to the closeness of the exciting radiation wavelength to the fundamental absorption edge of an analyzed object.     

生物材料玻璃化保存方法研究进展

生物材料的玻璃化保存技术一直是低温生物学领域的研究热点,提高冷却速率是实现玻璃化保存的一条途径。介绍了常用玻璃化保存方法的操作方法,分析比较了其冷却速率和保存效果,并提出了一种新颖的玻璃化保存法。     

Piezoelectricity in polymers and biological materials

The piezoelectric effect in polymers is usually explained in terms of the uniaxial orientation of the polymer crystallites and the classical piezoelectric property of these crystallites. Polarization caused by stress gradient seems to be necessary to the understanding of the geometrical relationship between stress and polarization. Studies of the temperature variation of the complex piezoelectric modulus have revealed a new type of relaxation phenomenon, which is closely related to elastic and dielectric relaxation. The possibility of a polymer piezoelectric transducer has been demonstrated by a microphone using an elongated film of poly-γ-methyl-L-glutamate. The physiological significance of piezoelectricity in biological polymers, such as its correlation with the growth mechanism of bone and with the sense of a mechanical stimulus, is worth further investigation.     

On the mechanisms of interaction of low-intensity millimeter waves with biological objects

The interaction of low-intensity millimeter-band electromagnetic waves with biological objects is examined. These waves are widely used in medical practice as a means of physiotherapy for the treatment of various human disorders. Principal attention is given to the mechanisms through which millimeter waves act on the human organism.Institute of Radio Engineering and Electronics, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 1, pp. 30–41, January, 1994.     

Nanodispersive mixed oxides for destruction of warfare agents prepared by homogeneous hydrolysis with urea

Nanocrystalline mixed oxides of Ti, Zn, Al and Fe were prepared by a homogeneous hydrolysis of sulphates with urea at temperature of 100 °C in an aqueous solution. The prepared samples were characterized by BET and BJH measurements, an X-ray powder diffraction and scanning electron microscopy. These oxides were taken for an experimental evaluation of their reactivity with yperite (2,2′-dichloroethyl sulphide), soman (3,3-dimethyl-2-butyl methylphosphonofluoridate) and matter VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothionate). An excellent activity in decomposition of chemical warfare agents was observed in these materials (conversion degree higher then 96%/h).     

Probability of lethal damages of cryopreserved biological objects during storage

This study demonstrated that with a cyclic change of the temperature from -196 degree C up to -130 degree C or -100 degree C part of cryopreserved microorganisms, tumor and human embryo cells died. This should be taken into account when moving and transporting the cryopreserved objects. Storage of samples under the above-mentioned stable temperatures did not result in additional death of cells.