EC-QCL中红外激光外差光谱遥测技术研究

具有高灵敏度、高光谱分辨率的中红外激光外差光谱气体探测,是以窄线宽激光器作为本地振荡器,通过放大入射的微弱吸收信号,实现大气痕量气体柱浓度和垂直浓度廓线的遥感探测技术。基于当前的激光外差辐射计,提出了一种新型的仪器结构。引入直接吸收光谱系统实现外差系统工作波长的选定和频率标定。采用紧凑型红外黑体源EMIRS200作为宽带辐射光源,替代太阳光,进行激光外差系统的验证分析。为激光外差辐射计的下一步系统集成提供了新方法。研制了中红外宽调谐激光外差辐射计概念验证系统,对系统基本参数进行了测试分析。该系统采用8μm外腔量子级联激光器(EC-QCL)作为本地振荡光源,红外黑体源EMIRS200作为辐射光源。通过对该系统基本参数的测试数据分析,获得了系统信噪比(~120)和外差转换效率(~0.006)参数。利用艾伦方差分析确定了EC-QCL的稳定时间至少达到了133 s,因此非常适合于激光外差光谱的采集。得到直接吸收光谱系统的1σ最小体积分数探测限为2.312×10^(-8),能够满足大气甲烷高灵敏检测需求,同时实现外差系统工作波长的选定和频率标定。最后利用已建立的激光外差辐射计概念验证系统获取了甲烷中红外8μm处高分辨激光外差吸收光谱,并与甲烷在8μm波段附近的直接吸收光谱进行了光谱比对。最后拟合了系统光谱分辨率参数,验证了该概念验证系统的高光谱分辨率,能满足较窄线宽条件下的高分辨率激光外差光谱的测量。实验结果表明,激光外差系统中引入直接吸收光谱系统可以实现外差系统工作波长的选定和频率标定。紧凑型红外黑体源EMIRS200可以用于激光外差辐射计的结构优化,实现激光外差系统的分析验证,为进一步应用于测量实际大气中多组分气体的光谱提供了实验基础并拓展激光外差辐射计在高精度遥感探测领域的应用。

Thermoelectric generators and their applications:Progress,challenges,and future prospects

Our community currently deals with issues such as rising electricity costs,pollution,and global warming.Scientists work to improve energy harvesting-based power generators in order to reduce their impacts.The Seebeck effect has been used to illustrate the capacity of thermoelectric generators(TEGs)to directly convert thermal energy to electrical energy.They are also ecologically beneficial since they do not include chemical products,function quietly because they lack mechanical structures and/or moving components,and may be built using different fabrication technologies such as three-dimentional(3D)printing,silicon technology,and screen printing,etc.TEGs are also position-independent and have a long operational lifetime.TEGs can be integrated into bulk and flexible devices.This review gives further investigation of TEGs,beginning with a full discussion of their operating principle,kinds,materials utilized,figure of merit,and improvement approaches,which include various thermoelectric material arrangements and utilised technologies.This paper also discusses the use of TEGs in a variety of disciplines such as automobile and biomedical.

Multiomic investigation of Sugarcane mosaic virus resistance in sugarcane

Sugarcane mosaic virus(SCMV)is the main etiological agent of sugarcane mosaic disease,which affects sugarcane and other grass crops.Despite the extensive characterization of quantitative trait loci controlling resistance to SCMV in maize,the genetic basis of this trait in sugarcane is largely unexplored.Here,a genome-wide association study was performed and machine learning coupled with feature selection was used for genomic prediction of resistance to SCMV in a diverse sugarcane panel.Nine single-nucleotide polymorphisms(SNPs)explained up to 29.9%of the observed phenotypic variance and a 73-SNP set predicted resistance with high accuracy,precision,recall,and F1 scores(the harmonic mean of precision and recall).Both marker sets were validated in additional sugarcane genotypes,in which the SNPs explained up to 23.6%of the phenotypic variation and predicted resistance with a maximum accuracy of 69.1%.Synteny analyses suggested that the gene responsible for the majority of SCMV resistance in maize is absent in sugarcane,explaining why this major resistance source has not been identified in this crop.Finally,using sugarcane RNA-Seq data,markers associated with resistance to SCMV were annotated,and a gene coexpression network was constructed to identify the predicted biological processes involved in resistance.This network allowed the identification of candidate resistance genes and confirmed the involvement of stress responses,photosynthesis,and the regulation of transcription and translation in resistance to SCMV.These results provide a practical marker-assisted breeding approach for sugarcane and identify target genes for future studies of SCMV resistance.

Activity and Selectivity of Bimetallic Catalysts Based on SBA-15 for Nitrate Reduction in Water

Nitrate from the application of nitrogen-based fertilizers in intensive agriculture is a notorious waste product, though it lacks cost-effective solutions for its removal from potential drinking water resources. Catalytic reduction appears to be a promising technique for converting nitrates to benign nitrogen gas. Mesoporous silica SBA-15 is a frequently used catalyst support that has large surface areas and highly ordered nanopores. In this work, mesoporous silica SBA-15 bimetallic catalysts for nitrate reduction were investigated. The catalyst was optimized for the selection of promoter metal (Sn and Cu), noble metal (Pd and Pt) and loading ratios of these metals at different temperatures and reduction conditions. The catalysts prepared were characterized by FT-IR, N2 physisorption, XRD, SEM, and ICP. All catalysts showed the presence of cylindrical mesoporous channels and uniform pore structures that remained even after metals loading. In the presence of a CO2 buffer, the catalysts 4Pd-1Cu/SBA-15 and 1Pt-1Cu/SBA-15 reduced at 100?C under H2 and 1Pd-1Cu/SBA-15 reduced at 200°C under H2 demonstrated very high nitrate conversion. Furthermore, the forementioned Pd catalysts had higher N2 selectivity (88% - 87%) compared to Pt catalyst (80%). Nitrate conversion by the 4Pd-1Cu/SBA-15 catalyst was significantly decreased to 81% in the absence of CO2.

Pore pressure prediction in offshore Niger delta using data-driven approach: Implications on drilling and reservoir quality

Despite exploration and production success in Niger Delta,several failed wells have been encountered due to overpressures.Hence,it is very essential to understand the spatial distribution of pore pressure and the generating mechanisms in order to mitigate the pitfalls that might arise during drilling.This research provides estimates of pore pressure along three offshore wells using the Eaton's transit time method,multi-layer perceptron artificial neural network(MLP-ANN)and random forest regression(RFR)algorithms.Our results show that there are three pressure magnitude regimes:normal pressure zone(hydrostatic pressure),transition pressure zone(slightly above hydrostatic pressure),and over pressured zone(significantly above hydrostatic pressure).The top of the geopressured zone(2873 mbRT or 9425.853 ft)averagely marks the onset of overpressurization with the excess pore pressure above hydrostatic pressure(P∗)varying averagely along the three wells between 1.06−24.75 MPa.The results from the three methods are self-consistent with strong correlation between the Eaton's method and the two machine learning models.The models have high accuracy of about>97%,low mean absolute percentage error(MAPE<3%)and coefficient of determination(R2>0.98).Our results have also shown that the principal generating mechanisms responsible for high pore pressure in the offshore Niger Delta are disequilibrium compaction,unloading(fluid expansion)and shale diagenesis.

Linear System Solutions of the Navier-Stokes Equations with Application to Flow over a Backward-Facing Step

Many applications in fluid mechanics require the numerical solution of sequences of linear systems typically issued from finite element discretization of the Navier-Stokes equations. The resulting matrices then exhibit a saddle point structure. To achieve this task, a Newton-based root-finding algorithm is usually employed which in turn necessitates to solve a saddle point system at every Newton iteration. The involved linear systems being large scale and ill-conditioned, effective linear solvers must be implemented. Here, we develop and test several methods for solving the saddle point systems, considering in particular the LU factorization, as direct approach, and the preconditioned generalized minimal residual (ΡGMRES) solver, an iterative approach. We apply the various solvers within the root-finding algorithm for Flow over backward facing step systems. The particularity of Flow over backward facing step system is an interesting case for studying the performance and solution strategy of a turbulence model. In this case, the flow is subjected to a sudden increase of cross-sectional area, resulting in a separation of flow starting at the point of expansion, making the system of differential equations particularly stiff. We assess the performance of the direct and iterative solvers in terms of computational time, numbers of Newton iterations and time steps.

4.4μm中红外激光外差光谱探测技术研究

在国内首次报道以窄线宽的4.4μm外腔量子级联激光（QCL）作为本地振荡光源,黑体作为辐射光源的激光外差光谱实验装置的建立和测量工作。激光外差光谱是一种高灵敏度的光谱探测技术,并可以用于发展一种小型的光谱探测系统,进行地基或星载的地球大气或天文观测。介绍了激光外差的基本理论、装置的建立和实验测量工作。此激光外差光谱实验装置采用4.4μm外腔量子级联激光,出光功率高达180mW,在4.38-4.52μm间连续可调,具有很宽的光谱调谐范围,能实现CO2,CO和N2O等大气重要分子的同时测量。通过开展不同压力下CO2气体的激光外差光谱测量,对激光外差光谱实验装置的性能进行了评估。目前该激光外差系统的信噪比达到86,低于散粒噪声极限条件的理论计算值287,系统的光谱分辨率约为0.007 8cm-1,能满足较窄线宽条件下的高分辨率激光外差光谱的测量。分析结果表明,中红外激光外差光谱系统具有很高的瞬态信噪比及光谱分辨率,在高精度测量大气温室气体的柱浓度和温室气体垂直廓线分布方面具有广阔的应用前景。

生物医学工程材料β磷酸三钙生物陶瓷的体外降解性能研究

目的对磷酸钙生物陶瓷在体外环境下的降解作用的定量和定性分析,评价其降解性能和生物学安全性。方法实验选用一种可控性微结构多孔生物陶瓷的不规则形颗粒,参照ISO10993-14的方法,将5g材料浸泡在极限溶液和模拟溶液中,经120h后分别过滤并称重,运用ICP法分析其滤液。结果在极限溶液中材料浸泡后残留质量增加63.7mg,滤液中钙、磷、钠含量明显增加;而在模拟溶液中浸泡后材料残留质量减少7.6mg,滤液中钙、磷含量增加。结论β-TCP多孔生物陶瓷在体外能被降解,其降解成分主要为钙和磷,为进一步探讨该材料的体内生物降解性奠定基础。

柱状多孔磷酸三钙载体内细胞增殖与流场变化的研究

目的通过流体力学模型分析三维灌注培养条件下载体内细胞增殖与流场变化的关系。方法利用灌注型生物反应器对复合骨髓基质干细胞的β-TCP载体进行动态灌注培养,对不同时间段的载体行组织形态学观察和计量,建立灌注系统的流体力学模型,比较载体不同区域细胞增殖速度与流场的关系。结果细胞在β-TCP载体内增殖速度随培养时间的延长而增加。培养1周,大部分区域细胞大多呈单层排列;培养2周,部分孔道已填满了细胞。培养4周,大部分孔道被细胞填满,有些区域细胞数量减少。建立载体随机孔道结构的流体分析模型发现,细胞生长较快区域对应的流速大多在0.14～0.64 mm/s,剪切应力在0.0029～0.017 Pa。结论载体内流体环境(流体剪切应力和流速)影响细胞在载体各个部位的生长,细胞生长导致载体内连通流道的结构和大小发生变化,其流体微环境亦随着发生变化,设计有利于成骨转化的载体结构要考虑这一因素。

β-TCP支架体外构建组织工程骨及其流体力学研究

骨髓基质干细胞在β-tricalciumphosphate(β-TCP)支架上分别进行了1、2和4周的三维动态培养,对支架上不同时间和部位的细胞面积/微孔面积及支架动态培养的流体环境进行了研究.研究表明,第1周细胞在支架大部分孔道内粘附生长并出现一定区域的单细胞层和多细胞层,第2周部分区域的部分孔道已填满了细胞并出现多细胞层,第4周大部分孔道几乎填满了细胞,主管道内壁出现了较多的细胞生长.同时发现,支架上各个区域细胞粘附面积不等,部分区域无细胞存在,有的部位2周后细胞逐渐减少.为了研究支架各个位置细胞増殖与流速、剪切应力的关系,建立了支架随机孔道结构的流体分析模型,通过支架上流速和剪切应力分布探讨实验中细胞分布现象的机理.结合计算和实验发现,流体能流到的部位几乎都有细胞生长,细胞生长较快的部位速度大多集中在0.24～0.53mm/s,剪切力大多在0.0050～0.023Pa,主管道底部及靠近进口的部位可能存在由于过大的剪切力影响细胞生长的区域.上述结果在一定程度上反映了细胞-支架-流体三者在成骨转化过程中的作用,对指导体外灌注培养的流量确定、灌注工艺及骨转化动力学研究有重要的意义.

非相干宽带腔增强吸收光谱技术应用于大气中HONO和NO2的实时探测

介绍了基于紫外LED光源的非相干宽带腔增强吸收光谱装置,并将其应用于实际大气中的HONO和NO2浓度的探测。中心波长为365nm的UV-LED出射光被耦合到~1.76m长,由两片高反射率镜片组成的光学谐振腔内,透过腔的光由便携式CCD光谱仪接收。高反射率镜片的反射率由NO2和O2-O2的吸收谱来校正,在353~376nm的测量范围内,最高反射率为0.999 17。在120s的采集时间内,HONO和NO2的探测极限（1σ）分别为0.6和1.8ppbv。将该装置测量的连续56h大气中NO2浓度的变化与配备蓝光转换器的NOx分析仪测量的结果进行比较,线性相关系数R2=0.89,斜率为1.09,截距为3.45。基于该装置探测了实验室大气中的HONO和NO2昼夜浓度变化,24h内的HONO浓度在0~5.3ppbv之间波动,平均浓度为1.8ppbv,NO2浓度变化范围为5~51ppbv,平均浓度为21.9ppbv。

^13CH4分子ν3振动带空气和氮气加宽系数温度依赖性研究

采用中红外波段连续可调谐二极管激光器和自行研制的低温吸收池,测量了温度为296 K,252 K,213K,173 K时,3.38μm附近13CH4分子的四条跃迁谱线的氮气和空气加宽光谱;首次通过实验获得空气和氮气对13CH4分子的碰撞加宽系数,以及谱线加宽系数的温度依赖系数.实验过程中,利用Voigt线型对所测量的光谱进行拟合.实验结果表明,氮气和空气对13CH4分子的碰撞诱导加宽系数随温度的降低而增大;相同温度下,氮气对13CH4分子的碰撞加宽系数普遍大于空气加宽系数.实验数据为地球和外星体大气遥感探测提供了依据.

基于拉曼光谱和多元统计分析技术的结肠癌早期诊断

为了寻找结肠癌的病理发展规律在拉曼光谱属性上的体现,采用共聚焦显微拉曼光谱仪对60例离体的正常结肠组织、腺瘤性息肉和腺癌组织的近红外拉曼光谱进行对比检测,初步探讨了三类组织的拉曼光谱特征及其改变的规律。结果表明:三类组织拉曼光谱的差异明显存在于830,855,1 032,1 210,1 323,1 335,1 445,1 450,1 655 cm-1处,腺瘤性息肉的光谱大体位于正常组织与腺癌组织之间。以组织病理诊断为金标准,主成分分析结合线性判别分析技术建立的诊断算法区分3类组织的灵敏度分别为96.9%、85.7%和97.3%,特异性分别为82.8%、90%和92.3%。因此,拉曼光谱有潜力在分子水平上区分正常结肠组织、腺瘤性息肉和腺癌组织,有望成为结肠癌早期诊断的一种有效方法。

2μm附近CO2谱线参数测量及应用

吸收光谱技术用于痕量气体浓度监测,特别是在气体分子稳定同位素丰度探测中,吸收谱线参数的准确性非常重要,目前普遍使用的HITRAN数据库中给出的各项参数具有一定的不确定性。为利用2.0μm激光波段进行CO2浓度及其同位素丰度探测,需要对该波段的CO2吸收谱线参数进行校准,采用窄线宽分布反馈式二极管激光器作为光源,结合自行搭建的谱线参数测量系统,采集了2.0μm波段10条CO2吸收谱线,获得了各谱线的位置、强度、自加宽系数和N2加宽系数,并与HITRAN2012数据库中相应的数据进行对比发现两者之间吻合较好,CO2谱线强度和自加宽系数相对偏差均小于2%。实测实验室大气的CO2浓度为440ppm,13 CO2的丰度值δ为-9‰。测量结果为该波段应用于CO2浓度及13 CO2同位素丰度的实时在线探测提供了重要参考依据。

Recent advances in non-metal doped titania for solar-driven photocatalytic/photoelectrochemical water-splitting

Photocatalytic (PC) / Photoelectrochemical (PEC) water splitting under solar light irradiation is considered as a prospective technique to support the sustainable and renewable H_(2) economy and to reach the ultime goal of carbon neutral. TiO_(2) based photocatalysts with high chemical stability and excellent photocatalytic properties have great potential for solar-to-H_(2) conversion. To conquer the challenges of the large band-gap and rapid recombination of photo generated electron-holepairs in TiO_(2), non-metal doping turns out to be economic, facile, and effective on boosting the visible light activity. The localized defect states such as oxygen vacancy and Ti^(3+) generated by non-metal doping are located in the band-gap of TiO_(2), which result in the reduction of band-gap, thus a red-shift of the absorption edge. The hetero doping atoms such as B^(3+), I^(7+), S^(4+)/S^(6+), P^(5+) can also act as electron donors or trap sites which facilitate the charge carrier separation and suppress the recombination of electron-hole pairs. In this comprehensive review, we present the most recent advances on non-metal doped TiO_(2) photocatalysts in terms of fundamental aspects, origin of visible light activity and the PC / PEC behaviours for water splitting. In particular, the characteristics of different non-metal elements (N, C, B, S, P, Halogens) as dopants are discussed in details focusing on the synthesis approaches, characterization as well as the efficiency of PC and PEC water splitting. The present review aims at guiding the readers who want quick access to helpful information about how to efficiently improve the performance of photocatalysts by simple doping strategies and could stimulate new intuitive into the new doping strategies.

Multi-wavelength measurements of aerosol optical absorption coefficients using a photoacoustic spectrometer

The atmospheric aerosol absorption capacity is a critical parameter determining its direct and indirect effects on cli- mate. Accurate measurement is highly desired for the study of the radiative budget of the Earth. A multi-wavelength （405 rim, 532 nm, 780 nm） aerosol absorption meter based on photoacoustic spectroscopy （PAS） invovling a single cylin- drical acoustic resonator is developed for measuring the aerosol optical absorption coefficients （OACs）. A sensitivity of 1.3 Mm-l （at 532 nm） is demonstrated. The aerosol absorption meter is successfully tested through measuring the OACs of atmospheric nigrosin and ambient aerosols in the suburbs of Hefei city. The absorption cross section and absorption Angstrom exponent （AAE） for ambient aerosol are determined for characterizing the component of the ambient aerosol.

Cue hierarchy in the foraging behaviour of the brackish cladoceran Daphniopsis australis

Zooplankton communities are an essential component of marine and freshwater food webs. However, there is still a relative lack of information on how these organisms behaviourally respond to a range of abiotic and biotic stressors. Specifically, the behaviour of the cladoceran D aphniopsis australis, a species endemic to South-eastern Australian saline lakes and ponds, is still unknown despite its potential role in the structure and function of inland water ecosystems. The swimming behaviour of males, parthenogenetic females and epiphial females was investigated under various conditions and combinations of food and conspecific cues. In the absence of cues, males displayed the most extensive swimming behaviour, exploring all areas of the container, and swimming in a series of relatively straight trajectories. In contrast, females typically exhibited a hop-and-sink motion characterised by the alternation between short bursts of swimming and sinking phases. Both females spent long periods near the bottom of the container, but epiphial females appeared to be more active than parthenogenetic ones that rarely made an excursion in the water column. In the presence of cues, males and females showed abilities to detect infochemicals from food and conspecifics, but exhibited specific behavioural strategies. Males essentially increased their swimming speed in the presence of food and/or conspecific infochemicals, and this increase was independent on the source of the cues, i.e. food, conspecific or a mixture of food and conspecifics. In contrast, females exhibited cue hierarchies that were related to their sexual status. Parthenogenetic females swam faster in the presence of food and a mixture of food and conspecific infochemicals than in the presence of cue from the opposite sex, which did not significantly differ from control observations conducted in the absence of cues. Epiphial females decreased their swimming speed in the presence of cues, with the most significant behavioural answers being driven by sex-related cues.

Production of liquid bio-fuel from catalytic de-oxygenation:Pyrolysis of beech wood and flax shives

This study presents a detailed analysis of the catalytic de-oxygenation of the liquid and gaseous pyrolytic products of two biomasses (beech wood and flax shives) using different catalysts (commercial HZSM-5 and H-Y,and lab-synthesised Fe-HZSM-5,Fe-H-Y,Pt/Al2O3 and CoMo/Al2O3). The experiments were all conducted in a semi-batch reactor under the same operating conditions for all feed materials. BET specific surface area,BJH pore size distribution and FT-IR technologies have been used to characterise the catalysts,while gas chromatography-mass spectrometry (GC-MS),flame ionisation detection (GC-FID) and thermal conductivity detection (GC-TCD) were used to examine the liquid and gaseous pyrolytic products. It was firstly seen that at higher catalyst-to-biomass ratios of 4∶1,de-oxygenation efficiency did not experience any further significant improvement. FeHZSM-5 was deemed to be the most efficient of the catalysts utilised as it helped reach the lowest oxygen contents in the bio-oils samples and the second best was HZSM-5. It was also found that HZSM-5 and H-Y tended to privilege the decarbonylation route(production of CO),whilst their iron-modified counterparts favoured the decarboxylation one (production of CO2) for both biomasses studied. It was then seen that the major bio-oil components (carboxylic acids) underwent almost complete conversion under catalytic treatment to produce mostly unoxygenated aromatic compounds,phenols and gases like CO and CO2. Finally,phenols were seen to be the family most significantly formed from the actions of all catalysts.

Correlation and Cluster Analysis on the Quality Characters of New Middle-ripe Japonica Rice Varieties in Jiangsu Province

[ Objective] This study aimed to analyze the quality characteristics of the new middle-ripejapon/ca rico varieties in Jiangsu Province. [ Method] Four- teen new rice varieties included in the Middle-ripe Japon/ca Rice Regional Test in 2011 were selected as the materials. Correlation analysis and cluster analysis were carried out on their quality traits. [Result] The rice cultivars possessed stable characteristics, which were difficult to be further improved. In addition, their quality traits had extremely complicated relationships, and the differences were significant between different groups. [ Conclusion] This study will provide reference for improving the quality traits of japonica rice.

Low temperature laser absorption spectra of methane in the near-infrared at 1.65 μm for lower state energy determination

Direct absorption spectra of the 2v3 band of methane （CH4） from 6038 to 6050 cm 1 were studied at different low temperatures using a newly developed cryogenic cell in combination with a distributed feedback （DFB） diode laser. The cryogenic cell can operate at any stabilized temperature ranging from room temperature down to 100 K with temperature fluctuation less than =t=1 K within 1 hour. In the present work, the CH4 spectra in the range of 6038-6050 cm-1 were recorded at 296, 266, 248, 223, 198, and 176 K. The lower state energy Ett and the rotational assignment of the angular momentum J were determined by a ＂2-low-temperature spectra method＂ using the spectra recorded at 198 and 176 K. The results were compared with the data from the GOSAT and the recently reported results from Campargue and co-workers using two spectra measured at room temperature and 81 K. We demonstrated that the use of a 2-low-temperature spectra method permits one to complete the Ett and J values missed in the previous studies.