Application of AMS <Superscript>14</Superscript>C measurements to criminal investigations

¹⁴C variations of atmospheric CO₂ as well as carbonaceous fraction of living materials, such as collagen from tooth and bone, tissue, skin, hair, nail, etc., of modern humans are influenced by ¹⁴C produced artificially by nuclear bomb tests in the atmosphere from late 1950s to early 1960s. By careful investigation of ¹⁴C concentration of tree rings and human body samples formed in this time intervals, we can establish a relationship of their ¹⁴C concentrations with calendar year. By applying this relation to a sample whose ¹⁴C concentration can be measured, we can estimate the formation age of the sample. In addition, sources of the chemicals that were used in some criminal cases can be possibly identified, by their carbon isotope ratios (¹³C/¹²C and ¹⁴C/¹²C). This method of age determination has been applied to a forensic study, i.e., two criminal cases of murder. For each case, by comparing the measured ¹⁴C abundances of several pieces of hair and one tooth (the third molar) from the body with the annual change on concentrations of bomb-produced ¹⁴C, the time of death of the body and the age of the victim were estimated. The estimated values were consistent with the real ones that were revealed by the confession of the real murderers.     

Syntheses,Characterization and Crystal Structures of Three Structurally Similar Dinuclear Schiff Base Cadmium(II) Complexes with Bridging Azide or Thiocyanate Ligands

Three novel Schiff base cadmium(II) complexes, derived from the end‐on (μ‐1,1‐N₃) azide or end‐to‐end (μ‐1,3‐NCS) thio cyanate bridges and similar tridentate Schiff base ligands, have been synthesized under similar synthetic procedures and their crystal structures determined by X‐ray diffraction methods. They are the dinuclear double end‐on azide‐bridged [Cd₂(L1)₂(N₃)₂(μ‐1,1‐N₃)₂] ( 1 ), the dinuclear double end‐on azide‐bridged [Cd₂(L2)₂(N₃)₂(μ‐1,1‐N₃)₂] ( 2 ), and the dinuclear double end‐to‐end thiocyanate‐bridged [Cd₂(L3)₂(NCS)₂(μ_1,3‐NCS)₂] ( 3 ), where L1, L2 and L3 are three similar tridentate Schiff bases obtained by condensation of 2‐pyridylaldehyde with N,N‐diethylethane‐1,2‐diamine, of 2‐pyridylaldehyde with N‐isopropylethane‐1,2‐diamine, and of 2‐pyridylaldehyde with N,N‐dimethylpropane‐1,3‐diamine, respectively. Each cadmium(II) centre in the complexes is in a distorted octahedral coordination. There is a crystallographic inversion centre in each of the complexes. The similar small ligands used as the secondary ligands in the preparation of the cadmium(II) complexes with similar Schiff bases can result in similar structures.     

Alternating DNA and pi-conjugated sequences. Thermophilic foldable polymers

Foldable polymers with alternating single-strand deoxyribonucleic acid and planar conjugated organic perylene tetracarboxylic diimide units were found to self-organize into loosely folded nanostructures. Upon heating, the loosely folded structures become more ordered as evidenced by pi-stacking in the perylene segments. The folding and unfolding processes driven by the molecular interactions of adjacent perylenes were monitored in both aqueous and organic solutions. Heat-promoted folding, or inverse temperature behavior, which originates from positive enthalpy changes, was only observed in water. Therefore, we attributed this inverse temperature dependence to hydrophobic effects rather than pi-pi molecular orbital overlap between the perylene planes. These findings shed light on the design of new thermophiles in protein engineering as well as the construction of macromolecular-based nanodevices with actuator and sensory properties.     

咪唑-金属配合物的合成、性质及其与DNA的作用机理

Three hexakis（imidazole）metallo complexes of Co, Cd and Ni were synthesized and spectroscopically characterized. The crystal and molecular structures have been determined by X-ray crystallography analysis. The metal ions have an octahedral geometry with the MN6 chromophore. The electrochemical experimental results indicate that both [Co（Im）6]C12·2HCl·2H2O （1） and [Ni（Im）6]C12·4H2O （3） [Im=imidazole] could interact with DNA mainly by intercalation.     

新式夹心型光透薄层光谱电化学电解池

本文设计了一种新式夹心型光透薄层紫外-可见光谱电化学池。该池采用铂网工作电极,两侧平行放置铂片为对极置于同一石英窗口夹层中,同时以聚四氟乙烯隔离膜作为边际限制器,结合池内小孔道设置内参比点进行精确的电位控制,具有理想的光谱电化学响应。利用循环伏安、循环电位-吸收、恒电位现场光谱、双电位跃-计时电量、双电位跃-计时吸收等技术,对铁氰化钾在氯化钾溶液中的行为进行了表征。     

激光诱导击穿光谱(LIBS)技术在低碳钢铁冶金行业的应用

激光诱导击穿光谱技术(Laser induced breakdown spectroscopy,简称LIBS)是一种基于激光等离子体的发射光谱技术,具有样品制备简单,分析迅速,多元素同时分析,现场在线和远程分析等独特优势,已在钢铁冶金领域取得了越来越广泛的应用与发展。综述了近年来LIBS技术在钢铁冶金领域的应用研究进展,从冶金生产的全流程进行介绍,包括矿石、熔融钢水/铁水、钢铁产品及炉渣和废气分析。同时,还总结了LIBS技术在钢铁冶金领域应用的优点和缺点,并对该技术的应用前景及未来发展方向进行展望。     

In vivo mechanical study of helical cardiac pacing electrode interacting with canine myocardium

Cardiac pacing is a medical device to help human to overcome arrhythmia and to recover the regular beats of heart. A helical configuration of electrode tip is a new type of cardiac pacing lead distal tip. The helical electrode attaches itself to the desired site of heart by screwing its helical tip into the myocardium. In vivo experiments on anesthetized dogs were carried out to measure the acute interactions between helical electrode and myocardium during screw-in and pull-out processes. These data would be helpful for electrode tip design and electrode/myocardium adherence safety evaluation. They also provide reliability data for clinical site choice of human heart to implant and to fix the pacing lead. A special design of the helical tip using strain gauges is instrumented for the measurement of the screw-in and pull-out forces. We obtained the data of screw-in torques and pull-out forces for five different types of helical electrodes at nine designed sites on ten canine hearts. The results indicate that the screw-in torques increased steplike while the torque–time curves presente saw-tooth fashion. The maximum torque has a range of 0.3–1.9 N mm. Obvious differences are observed for different types of helical tips and for different test sites. Large pull-out forces are frequently obtained at epicardium of left ventricle and right ventricle lateral wall, and the forces obtained at right ventricle apex and outflow tract of right ventricle are normally small. The differences in pull-out forces are dictated by the geometrical configuration of helix and regional structures of heart muscle.     

Flavonoids from Lycium barbarum Leaves Exhibit Anti-Aging Effects through the Redox-Modulation

Lycium barbarum leaves are a kind of vegetable, and modern nutrition studies have found that they have an anti-aging function. Our study aims to investigate the anti-aging effects of Lycium barbarum leaf flavonoid (LBLF) extracts and its underlying molecular mechanism. LBLFs were purified using D101 and polyamide resin, characterized by ultraperformance liquid chromatography coupled with mass spectrometry, and administered to hydrogen peroxide (H₂O₂)-treated human umbilical vein endothelial cells (HUVECs) and Caenorhabditis elegans. Appropriate enrichment conditions were optimized through dynamic adsorption and desorption experiments, the content of flavonoids reached 909.84 mg/g, rutin and kaempferol being the main ones. LBLFs attenuated H₂O₂-induced HUVEC apoptosis, decreased reactive oxygen species and malondialdehyde production levels, increased superoxide dismutase, glutathione peroxidase and catalase activities. Furthermore, pre-treatment with LBLF increased mRNA expression of erythropoietin (EPO) and heme oxygenase-1 (HO-1) via the mitogen-activated protein kinase (MAPK) signaling pathway in HUVECs. Compared with 100 µM rutin monomer, LBLF prolonged the lifespan of Caenorhabditis elegans, enhanced their mobility in middle life stages and upregulated expression of sod-2, gcs-1 and skn-1 genes, which indicated that the anti-aging effects of LBLF were due to its redox-modulation.     

“Click handle”-modified 2′-deoxy-2′-fluoroarabino nucleic acid as a synthetic genetic polymer capable of post-polymerization functionalization

The functions of natural nucleic acids such as DNA and RNA have transcended genetic information carriers and now encompass affinity reagents, molecular catalysts, nanostructures, data storage, and many others. However, the vulnerability of natural nucleic acids to nuclease degradation and the lack of chemical functionality have imposed a significant constraint on their ever-expanding applications. Herein, we report the synthesis and polymerase recognition of a 5-(octa-1,7-diynyl)uracil 2′-deoxy-2′-fluoroarabinonucleic acid (FANA) triphosphate. The DNA-templated, polymerase-mediated primer extension using this “click handle”-modified FANA (cmFANA) triphosphate and other FANA nucleotide triphosphates consisting of canonical nucleobases efficiently generated full-length products. The resulting cmFANA polymers exhibited excellent nuclease resistance and the ability to undergo efficient click conjugation with azide-functionalized molecules, thereby becoming a promising platform for serving as a programmable and evolvable synthetic genetic polymer capable of post-polymerization functionalization.

Polymerase-mediated incorporation of a “click handle”-modified fluoroarabinonucleic acid (cmFANA) triphosphate produces a new class of nuclease-resistant, evolvable genetic polymers that can be functionalized with azide-containing molecules.     

Established Liposome-Coated IMB16-4 Polymeric Nanoparticles (LNPs) for Increasing Cellular Uptake and Anti-Fibrotic Effects In Vitro

As a global health problem, liver fibrosis still does not have approved treatment. It was proved that N-(3,4,5-trichlorophenyl)-2(3-nitrobenzenesulfonamide) benzamide (IMB16-4) has anti-hepatic fibrosis activity. However, IMB16-4 displays poor water solubility and poor bioavailability. We are devoted to developing biodegraded liposome-coated polymeric nanoparticles (LNPs) as IMB16-4 delivery systems for improving aqueous solubility, cellular uptake, and anti-fibrotic effects. The physical states of IMB16-4−LNPs were analyzed using a transmission electron microscope (TEM), high-performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimeter (DSC). The results show that IMB16-4−LNPs increased the drug loading compared to liposomes and enhanced cellular uptake behavior compared with IMB16-4−NPs. In addition, IMB16-4−LNPs could repress the expression of hepatic fibrogenesis-associated proteins, indicating that IMB16-4−LNPs exhibited evident anti-fibrotic effects.