Latent Fingerprint Imaging Using Dy and Sm Codoped HfO2 Nanophosphors: Structure and Luminescence Properties

The development of latent fingerprints (LFPs) detected at the site of crime is considered as an imperative physical evidence in forensic investigations. Herein, a rapid and cost‐effective approach using nonhazardous Dy and Sm codoped HfO₂ nanophosphors is demonstrated to be utilized for LFP imaging. Sol–gel method can produce Dy and Sm codoped HfO₂ of monoclinic phase with crystallite size ranging from ≈10 to 25 nm. While selected area electron diffraction and lattice spacing calculated from high‐resolution transmission electron microscopy confirm monoclinic phase, Le‐Bail profile refinement of X‐ray diffraction (XRD) patterns demonstrate an exponential increase in lattice volume with incorporating various concentrations of Dy and Sm in HfO₂ lattice. Exciting Dy and Sm codoped HfO₂ with 393 nm photoluminescence spectra show emissions in blue, yellow, and near red regions emerging primarily due to energy transfer from Dy³⁺ to Sm³⁺ through multipolar interaction suggested by time resolved decay spectra. Combining excitation and emission spectra, an energy band diagram is proposed. Owing to excellent emissions, Dy and Sm codoped HfO₂ are explored for LFP imaging with good selectivity and resolution over multivariate surfaces like float glass and aluminum foil. The third‐level details like enclosure and termination–bifurcation are extracted due to nanosized nature of particles.     

蔬菜粉末荧光光谱测定及其在手印显现中的应用

对遗留在客体表面的手印进行提取和鉴定是侦破案件的重要依据。对在犯罪现场发现的手印进行固定提取时,首先应该使用没有破坏性的光学无损检验技术。实践表明光学无损检验技术对于绝大部分光滑客体上的手印都能取得很大的反差和较好的纹线细节,而对于光滑度较差的客体上的手印则需要使用有损的物理法和化学法对指印进行固定提取。其中粉末法和熏显法在手印显现中得到了广泛的应用,但是常用的绝大部分粉末和熏显物质对长期从事手印显现的工作人员身体有较大的毒副作用。而且绝大部分常用的荧光粉末需要在紫外线的激发下产生荧光,紫外线激发手印产生荧光的同时也常会激发承痕客体产生很强的背景荧光,进而降低了手印与背景的反差。因此寻找一种成本低廉、无毒无害、操作简单和应用性广泛的手印显现方法是当务之急。研究了三种无毒无害、成本低廉的蔬菜粉末的荧光性能,并且将其应用于手印显现中。首先通过荧光分光光度计测定西蓝花粉末、菠菜粉末和紫菜粉末的荧光激发光谱和荧光发射光谱。通过荧光测定发现,西蓝花粉末的荧光比菠菜粉末和紫菜粉末的荧光强很多,所以选择西蓝花粉末显现犯罪现场常见的疑难客体表面汗潜手印。实验结果表明：（1）西蓝花粉末、菠菜粉末和紫菜粉末都能发出荧光,荧光激发光谱峰值都在417 nm,荧光发射光谱峰值都在678 nm,其中西蓝花粉末发出的荧光最强。（2）将西蓝花粉末用于多色图案干扰的非渗透性和渗透性客体上的汗潜手印的显现中,在415 nm的紫光的照射下能够发出明亮的红色荧光。拍照荧光指印时在镜头前加上透过中心波长为680 nm左右的窄带通干涉滤光镜,结果显示手印纹线与背景反差强烈,纹线清晰连贯,消除背景的干扰。（3）与传统的荧光粉末显现法相比,该显现方法具有较高的显现灵敏度。（4）有些客体背景图案在415 nm的紫光的照射下也有发光,但与西蓝花粉末的非常强的荧光相比,背景的荧光弱得多,所以使得手印与背景之间形成了较大的反差并且纹线的细节特征清晰。（5）粗糙客体上手印的显现也获得了很大的反差,粗糙的背景没有对纹线形成干扰而形成了清晰连贯的纹线。（6）实验中使用的市售的西蓝花粉末具有颗粒细小、吸附能力强等特点,能够促进手印物质与西蓝花粉末之间的选择性吸附,进而进一步提高手印显现的灵敏度。     

Dimensional characterization of selected elements in airborne PM10 samples using μ‐SRXRF

Micro synchrotron radiation X‐ray fluorescence (μ‐SRXRF) is a powerful spectroscopy technique that uses synchrotron radiation to induce X‐ray fluorescence in samples and provides exhaustive information on the micron and submicron scale. Among the major advantages of μ‐SRXRF spectroscopy are its nondestructive nature and that samples can usually be analyzed without pretreatment. At the ESRF (Grenoble, France) ID‐21 beamline, we examined PM₁₀ samples collected at two sites in the Province of Trieste, Italy, in order to determine possible correlations among some low‐ to mid‐Z elements (S, Cl, K, Ca, Ti, V, Cr, Mn, and Fe), as well as investigated the possibility of using synchrotron radiation imaging techniques as a way to examine the granulometry of PM₁₀ particles containing the various chemical elements. A consistent significant correlation between Ca and S has been found, which, coupled with the data obtained in a related study, indicates that a major part of the sulfate is present as CaSO₄. Granulometry measurement via imaging techniques has shown that some elements such as Fe, Ca, and S are more amenable to this type of analysis than others. Additionally, the spatial homogeneity of a PM_2.5 certified reference material (NIST SRM‐2783) has been investigated by analyzing four adjacent areas on the certified sample (total area 1 mm²). The certified reference material has shown a percentage relative standard deviation less than 7% for Al, Si, P, S, Cl, K, Ca, V, Cr, and Fe, and close to 17% for Ti and Mn. Copyright © 2011 John Wiley & Sons, Ltd.     

Stable Fluorescence of Green‐Emitting Carbon Nanodots as a Potential Nanothermometer in Biological Media

Temperature measurement in biology and medical diagnostics is of great importance. Herein, a novel carbon nanodot (CND) based fluorescent nanothermometry device for spatially resolved temperature measurements is demonstrated. The fluorescence CNDs are prepared by a simple one‐pot solvothermal method using sucrose as carbon source. Resultant CNDs show stable green fluorescence at 520 nm with high quantum yield (≈6%). The fluorescence of resultant CNDs exhibits a reversible linear response to temperature in a wide range of 20–85 °C. Moreover, the temperature resolution better than 0.5 °C and high sensitive variation of ≈1.3% °C^?1 are observed in a broad physiological temperature range of 20–40 °C. Therefore, the as‐prepared CNDs possess high water solubility, stable fluorescence, small size, and good biocompatibility, which make them promising candidate for thermometry and cell imaging in biological media.     

Time-resolved imaging of latent fingerprints with nanosecond resolution

Imaging of latent fingerprints using time-resolved (TR) method offers a broader platform to eliminate the unwanted background emission. In this paper, a novel TR imaging technique is demonstrated and implemented, which facilitates the detection of latent fingerprints with nanosecond resolution. Simulated experiments were carried out with two overlapping fingerprints treated with two fluorescent powders having different lifetimes in nanosecond range. The dependence of the fluorescence emission intensity in nanosecond resolution of TR imaging is also revealed.     

LaPO_4∶Ce,Tb纳米荧光粉末的合成及其在指纹无损显现中的应用

采用溶剂热法在水和乙二醇的混合溶剂中合成出了高质量的LaPO_4∶Ce,Tb纳米荧光粉末。然后通过透射电子显微镜(TEM)、粉末X射线衍射(XRD)、荧光光谱(FS)等表征手段分别对稀土纳米荧光粉末的微观形貌、晶体类型、荧光性能进行了表征,合成纳米荧光粉末的形貌为单分散的纳米棒,平均长度为700nm、平均直径为20nm,其晶体结构为单斜LaPO_4晶型,并且在254nm紫外光照射下能够产生较强的绿色荧光。最后将合成的纳米荧光粉末应用于光滑客体表面汗潜指纹的无损显现中,并详细考察了指纹显现的对比度、灵敏度、选择性、背景干扰等指标。实验结果表明,使用LaPO_4∶Ce,Tb纳米荧光粉末显现的指纹在254nm紫外光的激发下能够产生明亮的绿色荧光,指纹乳突纹线部位连贯清晰、细微特征反映明显,指纹与客体之间的对比反差强烈、客体产生的背景干扰较小,因此该显现方法具有较高的对比度、灵敏度和选择性。本显现方法具有操作方法简单、显现效果优良、适用范围广泛等优点。本研究的重要创新之处在于,经LaPO_4∶Ce,Tb纳米荧光粉末显现后的指纹还可以进行后续的DNA提取及检测,这是传统的指纹显现粉末所不能及的。本研究为指纹物证和生物物证这两大物证的同时利用提供了有益参考。     

Facile One‐Pot Conversion of Petroleum Asphaltene to High Quality Green Fluorescent Graphene Quantum Dots and Their Application in Cell Imaging

Benefiting from the natural nano‐size graphene‐structure in natural asphaltene material, a facile one‐pot route, mild chemical oxidation of low‐value petroleum asphaltene followed by routine ammonium neutralization, is presented to produce high quality graphene quantum dots (GQDs). The asphaltene‐derived GQDs possess a variety of oxygen‐containing and nitrogen‐containing functional groups such as carboxyl, hydroxyl, amine, and nitro groups. They present such excellent fluorescence properties as stable ability to retain strong green fluorescence within a relative broad excitation range in a bio‐suitable pH range of 4–7, high photoluminescence quantum yield of 18% and good fluorescent stability against photobleaching. And they are much smaller and thinner than most reported GQDs, displaying good biocompatibility with low cytotoxicity, effective cellular uptake, and excellent fluorescent probe performance for cancer cell imaging.     

指纹紫外光谱特性研究及变化规律分析

指纹的唯一性和终身不变性使得指纹可以验证一个人的身份信息,在生物识别领域具有广泛的应用。汗潜指纹对紫外线有着特殊的反射、散射以及荧光特性,所以可以利用紫外波段对汗潜指纹进行提取,并且不污染现场和目标样本。目前对紫外波段的指纹提取已经有着广泛的研究,但对指纹随时间变化的研究较少,一般都是通过化学方法测量汗潜指纹成份含量的变化。研究发现,指纹各个组成成份的紫外光谱特性不同,且这些成份随时间的挥发程度也不一致,利用多通道紫外成像系统对汗潜指纹进行凝视成像,发现各通道成像DN值随时间推移的变化程度并不一样,可通过研究各通道DN值的变化对指纹进行时间分析。首先,利用紫外光谱仪和氙灯,对汗液、酒精、食用油等几种手指容易接触的物质的反射光谱进行研究,得到了这些物质的反射光谱特性。然后,针对这几种类型的指纹,研制了一套多通道紫外成像设备,分别在240~280 nm（通道1）、280~315 nm（通道2）以及315~340 nm（通道3）三个紫外通道对其进行凝视成像,得到清晰的指纹图像,将指纹图像嵴线上码值最高的10个点的平均值进行比较,得到不同通道DN值与时间变化的关系。实验结果发现,汗潜指纹在紫外波段具有良好的成像特性,其成像DN值随时间的推移逐渐降低,其中240~280 nm的通道1中三个指纹在第七天的成像DN值分别降为第一天的0.62, 0.60和0.59;320~340 nm的通道2中三个指纹在第七天的成像DN值分别降为第一天的0.57, 0.61和0.60;340~420 nm的通道3中三个指纹在第七天的成像DN值分别降为第一天的0.56, 0.63和0.58。实验结果表明,不同类型的指纹在紫外波段的光谱特性并不一致,成像DN并不相同,且随时间的变化规律也不一样,但指纹成份的挥发具有一定的规律,成像DN值从第一天到第七天降低至60%左右,可以一定程度上反映指纹的挥发性质。结合紫外多通道成像系统,可以很好的研究指纹的变化规律,为刑侦探测中指纹研究提供了一个重要的手段。     

The Application of CdTe/CdS in the Detection of Carcinoembryonic Antigen by Fluorescence Polarization Immunoassay

A novel and portable strategy based on fluorescence polarization immunoassay (FPIA) using quantum dots (QDs) was described in this study for simple, rapid, and sensitive detection of carcinoembryonic antigen (CEA). Under optimal conditions, the sensor has a wide dynamic range (from 0.5?ng/mL to 200?ng/mL) and a good correlation. The limit of detection (LOD) is 0.21?ng/mL (S/N?=?3). The sensor has been applied for detection of carcinoembryonic antigen in 10 human serum samples with the range of recovery from 92.1?% to 103.6?%. Furthermore, bioconjugation of the core–shell QDs with streptavidin (SA) has been successfully applied in immunofluorescent imaging of the human hepatocellular carcinoma (HEPG2) cell line. The experimental results demonstrated the successful application of QDs-based fluorescence polarization immunoassay for detection of target proteins of biomedical importance. This strategy shows great promise for clinical diagnoses and basic discovery with high sensitivity, good specificity, simple procedures and short analysis time.     

荧光指纹技术——化学试剂质量检测新工具

产品质量控制一直是工业生产的重点,但缺乏简便可靠的检查方法。利用荧光指纹技术对不同厂家和相同厂家不同批次的色谱纯正己烷进行了研究。结果表明,不同厂家和相同厂家不同批次的产品的荧光指纹都有差异,国产的正己烷普遍荧光峰数量多、强度高、变化大,反映出杂质种类多、含量高、产品质量不稳定的特点。而进口著名品牌的产品则荧光峰数量稳定,且强度低。这个研究表明,荧光指纹技术在产品质量检测方面具有潜在价值。     

Distinction and quantification of inorganic sulfur species including thiosulfate by X‐ray fluorescence (WD‐XRF)

Sulfur occurs in a variety of inorganic and organic compounds with oxidation states from ?II up to +VI. Differentiation of these species in solid geochemical samples can be challenging because of oxidation processes during sample preparation by acidic digestion. Applying pressed powder pellets and an analysis by wavelength‐dispersive X‐ray fluorescence minimises reactions with oxidants and water. Main subjects of this work were five inorganic sulfur species, sulfide ?II, elemental sulfur 0, thiosulfate +II, sulfite +IV, and sulfate +VI, and the determination of their fluorescence energies in the sulfur X‐ray spectra. S Kα_1,2 and S Kβ₁ can be observed for all species, S Kβ′ satellites only for species with coordinated oxygen. The results are in good agreement with previously published data. Yet none of the 38 investigated papers from the past 90 years reported S Kα_1,2 of thiosulfate, which was determined as E = 2,309.12 eV in this work apparently for the first time. Binary mixtures of sulfur species are strongly differing in their ability of being quantitatively differentiated, as a reliable quantification requires a sufficient difference of the respective fluorescence energies. Regression equations for each mixture can be used to calculate the ratio of mass fractions of the investigated species from the evaluated fluorescence energy. If boundary conditions are considered, the presented approaches can be applied for analyses of geochemical samples or quality control of technical products. The main advantage of the described methods is the option of implementation to everyday X‐ray fluorescence lab routine without substantial additional effort.     

Back focal plane imaging of Tamm plasmons and their coupled emission

The unique optical properties of Tamm plasmons (TPs) – such as flexible wavevector matching conditions including inplane wavevector within the light line, and existing both S‐ and P‐polarized TPs − facilitate them for direct optical excitation. The Tamm plasmon‐coupled emission (TPCE) from a combined photonic–plasmonic structure sustaining both surface plasmons (SPs) and TPs is described in this paper. The sensitivity of TPCE to the emission wavelength and polarization is examined with back focal plane imaging and verified with the numerical calculations. The results reveal that the excited probe can couple with both TPs and SPs, resulting in surface plasmon‐coupled emission (SPCE) and TPCE, respectively. The TPCE angle is strongly dependent on the wavelength allowing for spectral resolution using different observation angles. These Tamm structures provide a new tool to control the optical emission from dye molecules and have many potential applications in fluorescence‐based sensing and imaging.     

An integrated phase-resolved fluorescence imaging system with sub-nanosecond lifetime resolution

In this paper, a novel configuration of an integrated phase-resolved (PR) fingerprint fluorescence imaging system is proposed and implemented. In this integrated PR imaging system, a current modulated 402 nm dual diode laser is proposed to be the light source, to obtain both high laser power and easy modulability. To estimate the lifetime resolution of this PR imaging system, a novel method of using distance-selective suppression of fluorescence signals from two identical fluorescing samples is proposed. Detailed theoretical and experimental analyses are presented. The experimental results demonstrate that this integrated PR imaging system has a lifetime resolution of 0.1 ns. Fingerprint detection experiments are also carried out using this system with latent fingerprints deposited on substrates of aluminum foil and currency.     

钡钨阴极优化与热电子发射性能

分别从基体和铝酸盐两方面优化了钡钨阴极.在基体方面,首先采用窄粒度钨粉结合放电等离子体烧结获得了孔径分布窄的基体;再利用射频等离子体球化技术制备了球形钨粉,采用球形钨粉制备了多孔基体,获得了孔通道光滑、内孔连通性好、孔径分布更加窄的基体.与窄粒度钨粉基体相比,球形钨粉制备的阴极,空间电荷限制区的斜率由1.25增加至1.37,发射均匀性得到提高,拐点电流密度由6.6 A·cm^–2增至6.96 A·cm^–2.在此基础上,采用液相法改善了铝酸盐物相组成,发现空间电荷限制区的斜率增加至1.44,拐点电流密度增加至21.2 A·cm^–2.通过理论计算对钡钨阴极发射的物理本质进行了研究,发现钡钨阴极发射规律遵循偶极子理论.     

Highly Sensitive Synchronous Fluorescence Measurement of Danofloxacin in Pharmaceutical and Milk Samples Using Aluminium (III) Enhanced Fluorescence

A simple, rapid and sensitive constant wavelength synchronous fluorescence method is developed for the determination of danofloxacin (DAN) in pharmaceutical formulations and its residue in milk based on Al(III) enhanced fluorescence. The synchronous fluorescence intensity of the system is measured at 435?nm using ? λ?=?80?nm and an excitation wavelength of 280?nm. A good linear relationship between enhanced fluorescence intensity and DAN concentration is obtained in the range of 3-100?ng?mL(-1)(r (2)?=?0.9991). The limit of detection (LOD, S/N?=?3) of the present method is 0.9?ng?mL(-1). The proposed method can be successfully applied to the determination of DAN in pharmaceutical formulations and in milk without serious interferences from common excipients, metal ions and other co-existing substances. The method can be used as a rapid screening to judge whether the DAN residues in milk exceed Maximum Residue Limits (MRLs) or not.     

原子荧光法测定干酵母中微量砷和汞

氢化物 -原子荧光测定干酵母中微量的砷和汞 ,探讨了样品的消解条件 ,仪器工作参数 ,硼氢化钾浓度对测定的影响。该方法简便快速、结果准确、重现性好。加标回收率 As:98.99%,Hg:98.32 %。相对标准偏差 As:0 .1 1 %,Hg:0 .0 3%。     

Determination of gold and silver in dross using EDXRF technique

Gold and silver in dross were determined by energy‐dispersive X‐ray fluorescence technique. Sample was prepared by pressed pellet method using microcrystalline cellulose powder as binder, and a method of standard additions was used for quantification. L_β X‐ray of gold (11.4 keV) and K_β X‐ray of silver (24.9 keV) were used for analysis. The measured concentrations of gold and silver were 132 ± 8 and 1181 ± 84 mg kg^?1, respectively. The results were validated by instrumental neutron activation analysis technique. The t‐test indicated that there was no significant difference between results obtained by the two techniques. Energy‐dispersive X‐ray fluorescence is a simple, precise and accurate technique for the determination of gold and silver in dross. Copyright © 2014 John Wiley & Sons, Ltd.     

水溶性CdTe/CdS纳米晶表面SiO2壳层的反相胶束法包覆

"提出了一种水相中制备CdTe/CdS核壳结构纳米粒子的方法.用Te粉作为碲源,用Na2S作为硫源,在50 ℃下制备了CdTe/CdS核壳结构纳米粒子. 用紫外可见吸收光谱和荧光光谱分析了CdS壳层对CdTe核的影响. 随CdS壳层厚度的增加,紫外可见吸收光谱和荧光光谱均发生了红移. CdS壳层厚度较薄时,CdTe/CdS纳米晶的荧光强度较CdTe纳米粒子有显著提高;而CdS壳层厚度较厚时,CdTe/CdS纳米晶的荧光强度会逐渐降低. 用反相胶束法在CdTe/CdS核壳结构纳米粒子的表面包被一层SiO2,     

Structural Assignment of Stilbenethiols and Chalconethiols and Differentiation of Their Isomeric Derivatives by Means of 1H‐ and 13C‐NMR Spectroscopy

Abstract

The ¹H‐ and ¹³C‐NMR spectra of some substituted stilbenes and chalcones were assigned unambiguously on the basis of a combination of homo‐ (COSY) and heteronuclear (HETCOR) two‐dimensional methods, the chemical shifts, as well as spin‐coupling constants. The A_ik empirical parameters of the –O–C(S)–N(CH₃)₂, –S–C(O)–N(CH₃)₂, and –SH group were calculated to help predict the chemical shifts of substituted stilbenes, 4′‐nitrostilbenes, and chalcones. The ¹H‐ and ¹³C‐NMR spectra have been shown to be able to differentiate between the isomers of O‐stilbenyl (4, 5) and S‐stilbenyl N,N‐dimethylthiocarbamates (7, 8) as well as O‐chalconyl (6) and S‐chalconyl N,N‐dimethylthiocarbamates (9).     

三维荧光光谱结合PCA-SVM对几种浓香型白酒的鉴别

提出一种利用三维荧光光谱技术鉴别不同品牌浓香型白酒的方法。运用FLS920荧光光谱仪测量了七个不同品牌浓香型白酒的三维荧光光谱,不同品牌浓香型白酒的荧光光谱特征相似,仅凭荧光特征参数较难区分。采用求偏导和小波压缩相结合的数据预处理方法,求解光谱数据中每一激发波长下,荧光强度对发射波长的一阶和二阶偏导数,选取db7紧支撑正交小波对数据进行压缩,选择4尺度分解后的近似系数作为新的数据矩阵,然后做主成分分析(PCA)。将提取的主成分作为支持向量机(SVM)的输入,并利用K-fold交叉验证的方法寻找支持向量机的最优参数c和γ,建立不同品牌白酒的分类鉴别模型。从每个品牌白酒中随机选取14个样本,共98个样本组成训练集,其余的42个样本组成预测集。分别比较了数据不求偏导,对数据求一阶偏导和二阶偏导的预处理后对鉴别模型的影响。结果表明：三维荧光光谱经过二阶偏导的预处理后,结合主成分分析和支持向量机能很好地实现不同品牌浓香型白酒的分类鉴别,模型的准确率为98.98%,预测集的准确率为100%。该方法具有简单,快速,成本低的优点,可为中国白酒的检测和鉴别技术的发展提供帮助。