Parameter settings in a compact laser-nitriding system for titanium composed of a focused pulsed Nd:YAG laser and nitrogen gas blow

The aim of the present study was to form a nitride layer on a titanium (Ti) substrate through a compact laser-nitriding system comprising a focused pulsed Nd:YAG laser and nitrogen gas blow. To obtain a high-quality layer, the effects of pulse frequency and gas flow rate on the surface characteristics were investigated by using plasma emission analysis as well as X-ray analyses. Optical emission spectra from the laser-induced plasma mainly consisted of ionic Ti lines, and their intensities when the pulse frequency was 15 Hz were much higher than those for 8 Hz. Similarly, the reflections from the δ-TiN phase in the X-ray diffraction (XRD) pattern were enhanced when using 15 Hz. On the other hand, the flow rate of nitrogen gas blow had a significant effect on the thickness of the thin oxide layer that formed above the nitride layer. Using a lower flow rate resulted in the formation of a thicker oxide layer. The higher pulse frequency and the faster flow rate were beneficial for obtaining a higher-quality layer because of the enhancement of nitridation and the suppression of oxidation, respectively.     

Elemental Analysis of Cement by Calibration-Free Laser Induced Breakdown Spectroscopy (CF-LIBS) and Comparison with Laser Ablation – Time-of-Flight – Mass Spectrometry (LA-TOF-MS), Energy Dispersive X-Ray Spectrometry (EDX), X-Ray Fluorescence Spectroscopy (XRF), and Proton Induced X-Ray Emission Spectrometry (PIXE)

The purpose of the present study is to determine the elemental composition of Pakistani cement brands using calibration-free laser induced breakdown spectroscopy (CF-LIBS) and to compare the obtained results with the other analytical techniques such as, laser ablation – time-of-flight – mass spectrometry (LA-TOF-MS), energy dispersive X-ray spectrometry (EDX), X-ray fluorescence spectroscopy (XRF) and proton induced X-ray emission spectrometry (PIXE). Compositional results reveal that all the cement brands are mainly composed of calcium, silicon, iron, aluminum, magnesium, potassium, sodium, titanium, lithium and strontium with varying concentrations. The compositions obtained by LIBS and LA-TOF-MS are in good agreement with results obtained by the other standard techniques and demonstrate the potential use of LIBS for the online monitoring of industrial cement production.     

Uptake,Translocation, and Bioaccumulation of Elements in Forest Nettle (Laportea alatipes)

Elements found in the edible parts of plants are considered to be the main source of nutrients for humans and animals. However, there is insufficient information on the relationship between heavy metal pollution in the growing soil of most edible plants. In this study, the distribution of elements in the edible forest nettle (Laportea alatipes) was evaluated as a function of geographical location. Forest land soils had higher concentrations of minor elements (Cu, Cr, Ni, and Zn) compared to soils from rural and suburban areas. Translocation factors for Cd and Pb showed effective translocation from the roots to the leaves; however, these heavy metals in leaves were still above South African maximum permissible levels for vegetables. Atmospheric depositions may play a significant role in higher Cd and Pb concentrations in the leaves. Bioaccumulation factors showed the plant to accumulate Cu, Mn, and Zn to meet physiological requirement levels. Geoaccumulation indices and enrichment factors showed no soil contamination or minimal enrichment by trace metals. Principal component analysis showed Co, Cr, Cu, Fe, Ni, Pb, and Zn in soil to originate from a common source which may be soil silicates and other minerals.     

A zinc(Ⅱ) MOF based on secondary building units of infinite wavy-shaped chain exhibiting obvious luminescent sense effects

A new metal-organic framework (MOF),{[Zn_7 (BPS)_4 (OH)_6 (H_2O)_2]·5 H_2O]_n}(1), (H_2 BPS=4,4′-bibenzoic acid-2,2′-sulfone), based on a wavy and infinite chain-shaped secondary building units, has been synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction and further confirmed by PXRD, TGA and IR spectrum. The solid-state emission spectra reveal that compound 1 presents strong luminescence emission bands at room temperature. The fluorescent properties of compound 1 in diverse organic solvents indicated that 1 has palpable luminescent sense effects for DMF and DMAC.     

Enhanced deep-red emission in donor-acceptor molecular architecture:The role of ancillary acceptor of cyanophenyl

Organic solid-state luminescent materials with high-efficiency deep-red emission have attracted considerable interest in recent years.Constructing donor-acceptor(D-A) type molecules has been one of most commonly used strategies to achieve deep-red emission,but it is always difficult to achieve high photoluminescence(PL) quantum yield(η_(PL)) due to forbidden charge-transfer state.Herein,we report a new D-A type molecule 4-(7-(4-(diphenylamino)phenyl)-9-oxo-9 H-fluoren-2-yl)benzonitrile(TPAFOCN),deriving from donor-acceptor-donor(D-A-D) type 2,7-bis(4-(diphenylamino)phenyl)-9 Hfluoren-9-one(DTPA-FO) with a fluorescence maximum of 627 nm in solids.This molecular design enables a transformation of acceptor from fluorenone(FO) itself to 4-(9-oxo-9 H-fluoren-2-yl)benzonitrile(FOCN).Compared with DTPA-FO,the introduction of cyanophenyl not only shifts the emission of TPA-FOCN to deep red with a fluorescence maximum of 668 nm in solids,but also maintains the high η_(PL) of 10%.Additionally,a solution-processed non-doped organic light-emitting diode(OLED)was fabricated with TPA-FOCN as emitter.TPA-FOCN device showed a maximum luminous efficiency of0.13 cd/A and a maximum external quantum efficiency(EQE) of 0.22% with CIE coordinates of(0.64,0.35).This work provides a valuable strategy for the rational design of high-efficiency deep-red emission materials using cyanophenyl as an ancillary acceptor.     

飞行时间质谱仪固体样品自动进样系统研制

以常规型飞行时间质谱仪为基础,通过配置移动平台、样品杆、工业相机、LED灯源、工业显示屏等部件,研制了一套飞行时间质谱仪用固体样品自动进样系统,实现了固体有机样品的直接进样分析。该装置具有一定的普适性,可为相关实验室设备升级改造提供借鉴和参考。该装置可进行难溶未知有机化合物的结构剖析,实现目标物的快速筛查,且操作人员可实时观测锥孔处样品状态并可软件操控进样位置,实现人机分离的自动化测试。     

非典型发光化合物的簇聚诱导发光

不含大共轭结构的非典型发光化合物因其理论研究的重要性和潜在应用前景引起研究者的广泛关注。非典型发光化合物的结构通常含有N、O、S、P等杂原子,C≡N、C=O、C=C等不饱和单元,及相应的组合功能团(如羟基、胺基、酯基、酐、酰胺、脲基、肟基、砜基等)。近年来,尽管这一领域正快速发展,其发光机理仍存争议。前期,我们提出了簇聚诱导发光(CTE)机理,即含π电子和/或孤对(n)电子的非典型生色团的簇聚及其带来的空间共轭使体系离域扩展,构象刚硬化;同时,其他分子内/间相互作用也有利于簇生色团的刚硬化,从而易于受激发射。基于CTE机理,本文综述了非典型发光化合物的发光特性,包括浓度增强发光、聚集诱导发光(AIE)、激发波长依赖性及磷光发射。CTE机理可合理解释天然产物、合成化合物、生物分子等不同体系的光物理行为,并可用来指导发现和设计新的非典型发光化合物。本文总结了上述不同体系的发展,并对未来研究进行了展望。     

Characterization and tentative identification of new flunitrazepam metabolites in authentic human urine specimens using liquid chromatography‐Q exactive‐HF hybrid quadrupole‐Orbitrap‐mass spectrometry (LC‐QE‐HF‐MS)

Flunitrazepam (FNZ) is a potent hypnotic, sedative, and amnestic drug used to treat severe insomnia. In our recent study, FNZ metabolic profiles were investigated carefully. Six authentic human urine samples were purified using solid phase extraction (SPE) without enzymatic hydrolysis, and urine extracts were then analyzed by liquid chromatography‐Q exactive‐HF hybrid quadrupole‐Orbitrap‐mass spectrometry (LC‐QE‐HF‐MS), using the full scan positive ion mode and targeted MS/MS (ddms2) technique to make accurate mass measurements. There were 25 metabolites, including 13 phase I and 12 phase II metabolites, which were detected and tentatively identified by LC‐QE‐HF‐MS. In addition, nine previously unreported phase II glucuronide conjugates and four phase I metabolites are reported here for the first time. Eight metabolic pathways, including N‐reduction and O‐reduction, N‐glucuronidation, O‐glucuronidation, mono‐hydroxylation and di‐hydroxylation, demethylation, acetylation, and combinations, were implicated in this work, and 2‐O‐reduction together with dihydroxylation were two novel metabolic pathways for FNZ that were identified tentatively. Although 7‐amino FNZ is widely considered to be the primary metabolite, a previously unreported metabolites (M12) can also serve as a potential biomarker for FNZ misuse.     

“Aggregation-induced emission” of transition metal compounds: Design,mechanistic insights,and applications

In the last decades, compounds with ‘Aggregation-Induced Emission’ (AIE), which are weakly or non-emissive at all in solution but exhibit a strong luminescence in aggregated states, have emerged as an extraordinary breakthrough in the field of luminescent materials, allowing to circumvent ‘Aggregation Caused Quenching’ (ACQ), which in many cases prevents the development of efficient solid-state materials for optoelectronic applications.Since the discovery of AIE, many AIE-active materials have been developed, most of them composed of organic molecules, and thus fluorescent in nature. Although a wide range of applications such as bioimaging, sensing, multi-stimuli responsive materials, and optoelectronic devices have been proposed for this new class of materials, triplet harvesting phosphorescent materials have much longer lifetimes as compared to their singlet harvesting analogues, and for this particular reason, the development of AIE-active phosphorescent materials seems to be a promising strategy from the applications point of view. In this respect, the synthesis of new AIE-active systems including heavy metals that would facilitate the population of low-lying excited triplet states via spin-orbit coupling (SOC), for which the strength increases as the fourth power of atomic number, i.e. Z⁴, is highly desirable. This review covers the design and synthetic strategies used to obtain the AIEgens reported in the literature that contain either d-block metals such as Cu(I), Zn(II), Re(I), Ru(II), Pd(II), Ir(III), Pt(II), Au(I), and Os(IV), describing the mechanisms proposed to explain their AIE. New emerging high-tech applications such as OLEDs, chemical sensors or bioimaging probes proposed for these materials are also discussed in a separate section.