Studying the genotoxic effects of high intensity terahertz radiation on fibroblasts and CNS tumor cells

The data is obtained on the effect of high-intensity pulses of terahertz (THz) radiation with a broad spectrum (0.2–3 THz) on cell cultures. We have evaluated the threshold exposure parameters of THz radiation causing genotoxic effects in fibroblasts. Phosphorylation of histone H2AX at Ser 139 (γH2AX) was chosen as a marker for genotoxicity and a quantitative estimation of γH2AX foci number in fibroblasts was performed after cell irradiation with THz pulses for 30 min. No genotoxic effects of THz radiation were observed in fibroblasts unless peak intensity and electric field strength exceeded 21 GW cm⁻² and 2.8 MV cm⁻¹, respectively. In tumor cell lines (neuroblastoma (SK-N-BE (2)) and glioblastoma (U87)), exposure to THz pulses with peak intensity of 21 GW cm⁻² for 30 min caused no morphological changes as well as no statistically significant increase in histone phosphorylation foci number.     

小角X射线散射实验中蛋白质溶液的辐照损伤及防护方法

随着同步辐射光源（尤其是目前快速发展的第四代同步辐射光源）技术的进步,可用于实验的辐射通量越来越高,实验样品（特别是蛋白质等生物大分子样品）受到的辐照损伤也越来越严重。在全球现有的同步辐射装置上,蛋白质等生物大分子溶液专用小角X射线散射（SAXS）实验站的光子通量基本上都在1013cps量级。在如此高的通量下,蛋白质等生物大分子溶液样品在实验测量中受到的辐照损伤极其严重。如果没有有效的辐照防护措施,蛋白质溶液样品在毫秒级辐照时间内便会辐照损伤,导致不能获取有效的实验数据。辐照损伤严重制约了SAXS实验技术在蛋白质溶液样品方面的应用。因而,认识蛋白质溶液样品辐照损伤的产生机理、影响因素、判断标准,以及有效降低辐照损伤程度、延缓辐照损伤产生时间的方法,对于蛋白质等生物大分子溶液的散射实验具有重要的指导意义。本文在简要概述生物大分子溶液样品辐照损伤产生机理、影响因素、辐照剂量等基本概念的基础上,重点综述了同步辐射SAXS实验中辐照损伤的判断标准和防护措施。此外,本文还对比了各种防护措施的优缺点,讨论了在建HEPS新光源中SAXS束线可用的散射数据采集时间,指出辐照损伤防护剂是有价值的研究方向...     

Synchrotron-based Biological Microspectroscopy: From the Mid-Infrared through the Far-Infrared Regimes

Infrared radiation from synchrotron storagerings serves as a high-brightness source fordiffraction-limited microspectroscopy inboth the mid- and far-infrared spectralranges. Mid-infrared absorption, due to localvibrational modes within complex molecules,is shown to be sensitive to small chemicalchanges associated with certain diseases.Farinfrared modes are believed to result from thefolding or twisting of larger, morecomplex molecules. The ability for thesynchrotron source to perform microscopy ata frequency of 1 THz is demonstrated.     

Simulation,Fabrication and Characterization of THz Metamaterial Absorbers

Metamaterials (MM), artificial materials engineered to have properties that may not be found in nature, have been widely explored since the first theoretical¹ and experimental demonstration² of their unique properties. MMs can provide a highly controllable electromagnetic response, and to date have been demonstrated in every technologically relevant spectral range including the optical³, near IR⁴, mid IR⁵ , THz⁶ , mm-wave⁷ , microwave⁸ and radio⁹ bands. Applications include perfect lenses¹⁰, sensors¹¹, telecommunications¹², invisibility cloaks¹³ and filters^14,15. We have recently developed single band¹⁶, dual band¹⁷ and broadband¹⁸ THz metamaterial absorber devices capable of greater than 80% absorption at the resonance peak. The concept of a MM absorber is especially important at THz frequencies where it is difficult to find strong frequency selective THz absorbers¹⁹. In our MM absorber the THz radiation is absorbed in a thickness of ~ λ/20, overcoming the thickness limitation of traditional quarter wavelength absorbers. MM absorbers naturally lend themselves to THz detection applications, such as thermal sensors, and if integrated with suitable THz sources (e.g. QCLs), could lead to compact, highly sensitive, low cost, real time THz imaging systems.     

Electric-Field-Induced Shifts in the Infrared Spectrum of Conducting Nerve Axons

Difference spectra between resting and excited nerve in the infrared region between 2000 and 1000 cm^-1 have been examined with a resolution of 0.5 cm^-1. Spectra were obtained with a modified Perkin-Elmer model 521 grating infrared spectrophotometer (Perkin-Elmer Corp., Instrument Div., Norwalk, Conn.), and the signal-to-noise (S/N) ratio was improved by time averaging and digital smoothing. Peaks occurring in the regions around 1030 and 1066 cm^-1 are identified as P-O-C stretch, at 1410-1414 cm^-1 as C-H deformation, and at 1750 cm^-1 as carbonyl stretch. The difference peaks appear to be due to a shift of about 1 cm^-1 in the absorption band to lower frequencies for the three lower frequency bands and to a higher frequency for 1750 cm^-1 band. Since the difference peaks appear when the nerve is modulated by a propagated action potential it is concluded that the changing electrical field across the nerve membrane is perturbing the absorption spectrum. From evidence presented it appears likely that these difference peaks are due to phospholipids in the nerve membrane and that they may be related to conformational changes associated with membrane permeability.     

Molecular Beam Mass Spectrometry With Tunable Vacuum Ultraviolet (VUV) Synchrotron Radiation

Tunable soft ionization coupled to mass spectroscopy is a powerful method to investigate isolated molecules, complexes and clusters and their spectroscopy and dynamics^1-4. Fundamental studies of photoionization processes of biomolecules provide information about the electronic structure of these systems. Furthermore determinations of ionization energies and other properties of biomolecules in the gas phase are not trivial, and these experiments provide a platform to generate these data. We have developed a thermal vaporization technique coupled with supersonic molecular beams that provides a gentle way to transport these species into the gas phase. Judicious combination of source gas and temperature allows for formation of dimers and higher clusters of the DNA bases. The focus of this particular work is on the effects of non-covalent interactions, i.e., hydrogen bonding, stacking, and electrostatic interactions, on the ionization energies and proton transfer of individual biomolecules, their complexes and upon micro-hydration by water^{1, 5-9}.We have performed experimental and theoretical characterization of the photoionization dynamics of gas-phase uracil and 1,3-dimethyluracil dimers using molecular beams coupled with synchrotron radiation at the Chemical Dynamics Beamline¹⁰ located at the Advanced Light Source and the experimental details are visualized here. This allowed us to observe the proton transfer in 1,3-dimethyluracil dimers, a system with pi stacking geometry and with no hydrogen bonds¹. Molecular beams provide a very convenient and efficient way to isolate the sample of interest from environmental perturbations which in return allows accurate comparison with electronic structure calculations^{11, 12}. By tuning the photon energy from the synchrotron, a photoionization efficiency (PIE) curve can be plotted which informs us about the cationic electronic states. These values can then be compared to theoretical models and calculations and in turn, explain in detail the electronic structure and dynamics of the investigated species ^{1, 3}.     

Effects of THz Exposure on Human Primary Keratinocyte Differentiation and Viability

Primary human keratinocytes can be driven,in vitro, to differentiate, viaactivation of transglutaminases, by raisingthe culture medium calcium concentrationabove 1 mM. This results intransglutaminase regulated cross linking ofspecific amino acids with resultantcornified envelope formation. Thedifferentiation was monitored via theincorporation of fluorescein cadaverineinto the cornified envelops. Thisdifferentiation assay was combined withassessment of reductive capacity ofresazurin, as a measure of cellactivity/viability.One primary aim is to assess the effects ofTHz radiation on human skin, since medicalimaging of the body through the skin isenvisaged.Human keratinocytes, at passage 2 fromisolation, were grown to confluence, andtransported in a buffered salt solution at22 ^°C. The exposure to the THz sourcewas for 10, 20 or 30 minutes at roomtemperature.No donor specific inhibition or stimulationof cell activity, compared with non-exposedcells, was noted following exposure in therange 1 to 3 THz, at up to 0.45J/cm².The differentiation also occurred in anormal way, for exposed and non-exposedcells, with the FC incorporation increasingbetween day 3 and day 8, as previouslynoted.     

Terahertz Plasmonic Quantum Cascade Lasers: a Comprehensive Physics Study

Generation of terahertz (THz) radiation has been a hot research topic in recent years. Plasmonic quantum cascade lasers (QCLs) are among the most compact and efficient sources to generate THz radiation. In this paper, we comprehensively study plasmonic QCLs designed based on the antenna-feedback structure to generate efficient radiation about the center frequency of 3 THz. By changing the geometric structure of the plasmonic cavity and using two-dimensional simulation, a minimum loss less than 5.9 cm^?1 is achieved at the lasing frequency. It is also possible to control the orientation of the output beam either vertically or tilted by changing the geometry of the antenna design via chirped or non-chirped grating scheme. Moreover, the output characteristics of the QCL are simulated based on the three-level rate equations through which the dynamics of the laser, as well as the P-I curve, are investigated. Also, the gain spectra for two laser designs (with chirped and non-chirped gratings) are simulated and compared to each other. The results of this paper may provide deep insight into designing efficient laser sources in the THz region.

     

一种新型相干辐射--THz辐射在生物学中的应用

脉冲THz辐射是一种新型的远红外相干辐射源,近年来在不同的研究领域得到了广泛的应用。本文简要介绍THz辐射产生、探测的基本原理和方法;THz辐射的基本性质和它在生物学研究中应用的物理基础;对生物体系进行时域光谱分析和成像研究所取得的成果和最新进展,以及对该领域研究前景的展望。     

Biological applications of synchrotron radiation infrared spectromicroscopy

Extremely brilliant infrared (IR) beams provided by synchrotron radiation sources are now routinely used in many facilities with available commercial spectrometers coupled to IR microscopes. Using these intense non-thermal sources, a brilliance two or three order of magnitude higher than a conventional source is achievable through small pinholes (< 10 μm) with a high signal to-noise ratio. IR spectroscopy is a powerful technique to investigate biological systems and offers many new imaging opportunities. The field of infrared biological imaging covers a wide range of fundamental issues and applied researches such as cell imaging or tissue imaging. Molecular maps with a spatial resolution down to the diffraction limit may be now obtained with a synchrotron radiation IR source also on thick samples. Moreover, changes of the protein structure are detectable in an IR spectrum and cellular molecular markers can be identified and used to recognize a pathological status of a tissue. Molecular structure and functions are strongly correlated and this aspect is particularly relevant for imaging. We will show that the brilliance of synchrotron radiation IR sources may enhance the sensitivity of a molecular signal obtained from small biosamples, e.g., a single cell, containing extremely small amounts of organic matter. We will also show that SR IR sources allow to study chemical composition and to identify the distribution of organic molecules in cells at submicron resolution is possible with a high signal-to-noise ratio. Moreover, the recent availability of two-dimensional IR detectors promises to push forward imaging capabilities in the time domain. Indeed, with a high current synchrotron radiation facility and a Focal Plane Array the chemical imaging of individual cells can be obtained in a few minutes. Within this framework important results are expected in the next years using synchrotron radiation and Free Electron Laser (FEL) sources for spectro-microscopy and spectral-imaging, alone or in combination with Scanning Near-field Optical Microscopy methods to study the molecular composition and dynamic changes in samples of biomedical interest at micrometric and submicrometric scales, respectively.     

Estimating heat flux transmission of vertical greenery ecosystem

Nurturing vegetation on building envelopes provides an innovative and eco-friendly alternative to urban greening especially in compact cities. Whereas the thermal and other benefits of green roofs have been studied intensively, green walls have received scanty attention. This study evaluates the thermodynamic transmission process of the vertical greenery ecosystem. We designed a field experiment to monitor solar radiation and weather conditions, and developed a thermodynamics transmission model to simulate heat flux and temperature variations. The model was calibrated, tested, and proved to be highly efficient. The results show that seasonal global and direct solar radiation drops to minimum in winter in January and February, and reaches maximum in summer in July and August (1168 W m⁻² for global solar radiation and 889 W m⁻² for direct solar radiation). Diffuse solar radiation attains maximum in summer (586 W m⁻²) with moderate rainfall in July and August, and minimum in winter with no rainfall in January and February. Radiation transmission of the green wall strongly correlates with canopy transmittance and reflectance (R² = 0.83). Thermal shielding effectiveness varies with orientation, with the south wall achieving a higher coefficient (0.31) than the north wall. The south wall has lower heat flux absorbance and heat flux loss than the north wall. The south wall can transfer much more heat flux through the vertical greenery ecosystem due to more intensive canopy evapotranspiration effect. The model matches the transmission properties of green wall radiation, and the model simulation fits empirical transmission results.     

Studying the non‐thermal effects of terahertz radiation on E. coli/pKatG‐GFP biosensor cells

Studies of the impact of terahertz radiation on living objects present a significant interest since its use for security systems is currently considered promising. We studied the non‐thermal impact of terahertz radiation on E. coli/pKatG‐gfp biosensor cells. The Novosibirsk free electron laser (NovoFEL), which currently has the world's highest average and peak power, was used as the source of terahertz radiation. We demonstrated that exposure to terahertz radiation at the wavelengths of 130, 150, and 200 µm and a power of 1.4 W/cm² induces changes in green fluorescent protein (GFP) fluorescence values and thus induces the expression of GFP in E. coli/pKatG‐gfp biosensor cells. Possible mechanisms of the E. coli response to non‐thermal exposure to terahertz radiation are discussed. Bioelectromagnetics 34:15–21, 2013. © 2012 Wiley Periodicals, Inc.     

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies

The generation and subsequent measurement of far-infrared radiation has found numerous applications in high-resolution spectroscopy, radio astronomy, and Terahertz imaging. For about 45 years, the generation of coherent, far-infrared radiation has been accomplished using the optically pumped molecular laser. Once far-infrared laser radiation is detected, the frequencies of these laser emissions are measured using a three-laser heterodyne technique. With this technique, the unknown frequency from the optically pumped molecular laser is mixed with the difference frequency between two stabilized, infrared reference frequencies. These reference frequencies are generated by independent carbon dioxide lasers, each stabilized using the fluorescence signal from an external, low pressure reference cell. The resulting beat between the known and unknown laser frequencies is monitored by a metal-insulator-metal point contact diode detector whose output is observed on a spectrum analyzer. The beat frequency between these laser emissions is subsequently measured and combined with the known reference frequencies to extrapolate the unknown far-infrared laser frequency. The resulting one-sigma fractional uncertainty for laser frequencies measured with this technique is ± 5 parts in 10⁷. Accurately determining the frequency of far-infrared laser emissions is critical as they are often used as a reference for other measurements, as in the high-resolution spectroscopic investigations of free radicals using laser magnetic resonance. As part of this investigation, difluoromethane, CH₂F₂, was used as the far-infrared laser medium. In all, eight far-infrared laser frequencies were measured for the first time with frequencies ranging from 0.359 to 1.273 THz. Three of these laser emissions were discovered during this investigation and are reported with their optimal operating pressure, polarization with respect to the CO₂ pump laser, and strength.     

安吉毛竹林水汽通量变化特征及其与环境因子的关系

以浙江省安吉县毛竹(Phyllostachys edulis)林生态系统为研究对象,利用涡度相关技术进行观测,获取2011年毛竹林的水汽通量数据,同时结合常规气象观测数据,分析了水汽通量全年变化。结果表明:毛竹林全年水汽通量基本为正值,月尺度上,水汽通量呈单峰型变化趋势,且各月的最大值均在12:00—14:00出现,呈现一定规律性,7月(0.1116 g m-2s-1)最高,12月(0.0209 g m-2s-1)最低;季节尺度上,夏季最高(0.0873 g m-2s-1),呈现典型单峰型变化趋势,春秋季(均为0.0541 g m-2s-1)次之,变化特征与夏季相似,冬季最低(0.0221 g m-2s-1),曲线变化复杂,波动较大。毛竹林全年蒸散量占全年降水量48.26%。2、4、5、11、12月蒸散量略大于降水量,其余月份蒸散量均小于降水量,6月份降水量与蒸散量差别最大。季节尺度上,对毛竹林水汽通量与净辐射进行回归关系分析,夏季最大,R2为0.6111,秋季为0.5295,春季为0.2605,冬季最小0.0455。通过F检验,水汽通量与净辐射有极显著线性关系。在植物生长期,毛竹林水汽通量随饱和水汽压差的增大而增大,植物发育成熟后,当饱和水汽压差增大到一定程度时,其增大反而抑制了水分的蒸散。     

Estimated Ultraviolet Radiation Doses in Wetlands in Six National Parks

Ultraviolet-B radiation (UV-B, 280–320-nm wavelengths) doses were estimated for 1024 wetlands in six national parks: Acadia (Acadia), Glacier (Glacier), Great Smoky Mountains (Smoky), Olympic (Olympic), Rocky Mountain (Rocky), and Sequoia/Kings Canyon (Sequoia). Estimates were made using ground-based UV-B data (Brewer spectrophotometers), solar radiation models, GIS tools, field characterization of vegetative features, and quantification of DOC concentration and spectral absorbance. UV-B dose estimates were made for the summer solstice, at a depth of 1 cm in each wetland. The mean dose across all wetlands and parks was 19.3 W-h m⁻² (range of 3.4–32.1 W-h m⁻²). The mean dose was lowest in Acadia (13.7 W-h m⁻²) and highest in Rocky (24.4 W-h m⁻²). Doses were significantly different among all parks. These wetland doses correspond to UV-B flux of 125.0 μW cm⁻² (range 21.4–194.7 μW cm⁻²) based on a day length, averaged among all parks, of 15.5 h. Dissolved organic carbon (DOC), a key determinant of water-column UV-B flux, ranged from 0.6 (analytical detection limit) to 36.7 mg C L⁻¹ over all wetlands and parks, and reduced potential maximal UV-B doses at 1-cm depth by 1%–87 %. DOC concentration, as well as its effect on dose, was lowest in Sequoia and highest in Acadia (DOC was equivalent in Acadia, Glacier, and Rocky). Landscape reduction of potential maximal UV-B doses ranged from zero to 77% and was lowest in Sequoia. These regional differences in UV-B wetland dose illustrate the importance of considering all aspects of exposure in evaluating the potential impact of UV-B on aquatic organisms.     

Light-induced changes in the period of the circadian rhythm of carbon dioxide output in Bryophyllum leaves

Summary The period of the rhythm of carbon dioxide output from leaves of Bryophyllum fedtschenkoi R. Hamet et Perrier at 15°C was shorter in continuous white light than in darkness. The period was monitored in leaves exposed to narrow spectral bands of monochromatic radiation at an incident quantum flux density of 4.7×10^-11 einsteins cm^-2s^-1. Bands centred on 660, 600, 730 and 530 nm significantly shortened the period, the greatest effect being achieved at 660 nm and the smallest at 530 nm; those centred on 760 and 450 nm were without effect. None of the bands tested significantly lengthened the period. The period of the rhythm in leaves exposed continuously to monochromatic radiation at 660 nm decreased with increasing quantum flux density. The extent to which a quantum flux density of 4.7×10^-11 einsteins cm^-2s^-1 at wavelength 660 nm shortened the period depended on the ambient temperature. At 15°C a significant reduction of 4.4 h occurred as compared with the dark control, while at 30°C no significant reduction was observed. The transient (the time from the initiation of the rhythm to the first peak) showed a greater dependence on temperature than did the steady-state period. No such difference could be detected in relation to the intensity or quality of irradiation. The reduction of the transient by the various irradiation treatments was, in general, proportional to the reduction of the period.     

Thresholds of microwave-evoked warmth sensations in human skin

We measured thresholds for microwave-evoked skin sensations of warmth at frequencies of 2.45, 7.5, 10, 35, and 94 GHz. In the same subjects, thresholds of warmth evoked by infrared radiation (IR) were also measured for comparison. Detection thresholds were measured on the skin in the middle of the back in 15 adult male human subjects at all microwave (MW) frequencies and with IR. Long duration (10-s), large area (327-cm²) stimuli were used to minimize any differential effects of temporal or spatial summation. Sensitivity increased monotonically with frequency throughout the range of microwave frequencies tested. The threshold at 94 GHz (4.5 ± 0.6 mW/cm²) was more than an order of magnitude less than at 2.45 GHz (63.1 ± 6.7 mW/cm²), and it was comparable to the threshold for IR (5.34 ± 1.07 mW/cm²). Bioelectromagnetics 18:403–409, 1997. © 1997 Wiley-Liss, Inc.     

Primary Reactions of the LOV2 Domain of Phototropin Studied with Ultrafast Mid-Infrared Spectroscopy and Quantum Chemistry

Phototropins, major blue-light receptors in plants, are sensitive to blue light through a pair of flavin mononucleotide (FMN)-binding light oxygen and voltage (LOV) domains, LOV1 and LOV2. LOV2 undergoes a photocycle involving light-driven covalent adduct formation between a conserved cysteine and the FMN C(4a) atom. Here, the primary reactions of Avena sativa phototropin 1 LOV2 (AsLOV2) were studied using ultrafast mid-infrared spectroscopy and quantum chemistry. The singlet excited state (S1) evolves into the triplet state (T1) with a lifetime of 1.5 ns at a yield of ∼50%. The infrared signature of S1 is characterized by absorption bands at 1657 cm⁻¹, 1495-1415 cm⁻¹, and 1375 cm⁻¹. The T1 state shows infrared bands at 1657 cm⁻¹, 1645 cm⁻¹, 1491-1438 cm⁻¹, and 1390 cm⁻¹. For both electronic states, these bands are assigned principally to C=O, C=N, C-C, and C-N stretch modes. The overall downshifting of C=O and C=N bond stretch modes is consistent with an overall bond-order decrease of the conjugated isoalloxazine system upon a π-π^∗ transition. The configuration interaction singles (CIS) method was used to calculate the vibrational spectra of the S1 and T1 excited ππ^∗ states, as well as respective electronic energies, structural parameters, electronic dipole moments, and intrinsic force constants. The harmonic frequencies of S1 and T1, as calculated by the CIS method, are in satisfactory agreement with the evident band positions and intensities. On the other hand, CIS calculations of a T1 cation that was protonated at the N(5) site did not reproduce the experimental FMN T1 spectrum. We conclude that the FMN T1 state remains nonprotonated on a nanosecond timescale, which rules out an ionic mechanism for covalent adduct formation involving cysteine-N(5) proton transfer on this timescale. Finally, we observed a heterogeneous population of singly and doubly H-bonded FMN C(4)=O conformers in the dark state, with stretch frequencies at 1714 cm⁻¹ and 1694 cm⁻¹, respectively.     

A new approach to the characterization of the B and A forms of DNA by I.R. spectroscopy

The RNA conformational changes of B, A and C forms are reflected in the infrared absorption spectra in the region of 800 cm^?1 to 900 cm^?1 and allow one to investigate unoriented samples. The transition to the A form is characterized by the appearence of bands at about 870 cm^?1 and at 813 cm^?1 whereas the B and the C forms exhibit a band at 837 cm^?1, these bands undoubtedly arise from phosphate diester stretching vibrations and yield information about backbone conformation. The presence of these infrared bands provides a criterion for testing the simultaneous presence of two coexisting forms of DNA. It represents a useful method for structural studies of nucleic acid complexes such as protein-DNA for which it is difficult to obtain orientation.     

近48a华北区太阳辐射量时空格局的变化特征

以分析华北区太阳辐射量时空格局变化特征为研究目标,应用国家气象局整编的华北地区120个气象站点48a(1961-2008)的气象资料和中国数字高程模型,对48a来华北地区太阳辐射量进行计算及验证,并对空间格局及变异特征进行了探讨,结果表明:(1)华北地区太阳辐射量的年际间变化较大,总体呈下降趋势,线性倾向值为-7.72 MJ · m^-2 · a^-1;(2)太阳辐射量由多到少突变发生在1981年,1981-2008年太阳辐射量平均值较1961-1981年降低了203.92 MJ · m^-2 · a^-1。从1981年突变年开始,华北地区太阳辐射量表现出明显的下降趋势,且在分析期内,下降的态势得到持续发生;(3)1981/1982年度发生的太阳辐射量由多到少突变,大部分地区突变幅度在150 MJ/m²以上。突变严重的华北中部和南部地区,突变值可达300 MJ/m²;(4)突变年后,华北大部分地区均表现出持续下降的态势,下降速度在6 MJ · m^-2 · a^-1以上,其中华北东北部下降严重,下降速度可达15 MJ · m^-2 · a^-1。