尿素酶固载于纳米二氧化钛多孔膜上的尿素生物传感器

在钛丝基体上沉积一层纳米二氧化钛(TiO2)多孔膜,然后直接将尿素酶吸附在TiO2膜上。基于TiO2膜的pH响应,发展了一种廉价的、易于微型化的pH敏尿素酶传感器。采用石英微天平、红外光谱和紫外可见光谱等手段研究尿素酶在TiO2膜上的物理固载行为。由于纳米TiO2在紫外光下光自洁特性可获得高度洁净的表面,石英微天平研究表明在光自洁后的TiO2膜上尿素酶的吸附具有很好的重复性和稳定性,吸附量为0.22mmol/g,吸附平衡常数k为3.15×105L/mol。采用电位法测定了尿素酶/TiO2复合膜电极的性能及其影响因素,在1.0 mmol/L pH 7~8 PBS,35℃,尿素的响应范围为8.5×10-5~1.5×10-1mol/L,相关系数r为0.993 7,检出限为6×10-5mol/L。     

钙黄绿素蓝荧光法测定食品中的微量锌（Ⅱ）

本文研究了在ＣＴＭＡＢ存在下，用钙黄绿素蓝荧光法测定食品中的微量锌（Ⅱ）的实验条件。在本实验条件下，Ｚｎ（Ⅱ）与钙黄绿素蓝生成１：１的配合物使钙黄绿素蓝的荧光增强，最大激发波长和最大发射波长分别为３５３ｎｍ和４４０ｎｍ。     

Global activities in the world of reference materials including the needs of developing countries

Proceedings of previous BERM meetings have been used to assess emerging trends in the development of RMs to meet AQC requirements of clinical, food, nutrition, and environmental health areas. BRM-1 reflected a strong need to initiate and expand RM activities for certifying organic nutrients in foods. BRM-2 highlighted the distinction between primary (certified) and secondary (e.g. check samples for proficiency testing) RMs¹. BRM-3 identified the need for producing different levels of an analyte in a given matrix (spiked standards) to address matrix related measurement problems in foods. BERM-4 highlighted the need for a global vision in dealing with standards, illustrated by the activities of GESREM. Also, the logistics required for setting up intercomparison programs related to food safety monitoring programs were outlined. BERM-5 presented the changing outlook of the AOAC International in recognizing the usefulness of incorporating RMs for use in conjunction with their methods validation protocol. BERM-6 brought to the forefront the concern for traceability of chemical measurements to internationally recognized standards. BERM-7 recognized the need for multidisciplinary approaches for preparing certain types of CRMs, partly in response to the measurement needs arising from governmental regulations dealing with food safety and environmental health criteria. Finally, BERM symposia have promoted a meaningful dialogue on the RM needs of African, Asian and South American countries and provided the developing countries opportunities to discuss their problems with the international analytical community. The issue of health safety is involved in movement of foodstuffs between countries, and therefore, international efforts as voiced by the World Health Organization to provide guidance and assistance in AQC matters to the needy countries deserve consideration.     

Products active on mosquitoes,IV: Synthesis and biological activity of 8-propargyloxy-3,7-dimethyl-2,6-octadienyl/6-octenyl ethers

Summary A series of 8-proparglyoxy-3,7-dimethyl-2,6-octadienyl and 8-propargyloxy-3,7-dimethyl-6-octenyl ethers were prepared from 8-hydroxygeranyl and 8-hydroxycitronellyl ethers, respectively. Almost all compounds showed high toxicity toCulex quinquefaciatus larvae at 1 mgl^–1 dose level.

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Gegen Mücken aktive Produkte, 4. Mitt.: Synthese und biologische Aktivität von 8-Propargyloxy-3,7-dimethyl-2,6-octadienyl/6-octenyl-ethern

Zusammenfassung Eine Reihe von 8-Propargyloxy-3,7-dimethyl-2,6-octadienyl- und 8-propargyloxy-3,7-dimethyl-6-octenyl-ethern wurden aus 8-Hydroxygeranyl- bzw. 8-Hydroxycitronellyl-ethern hergestellt. Fast alle Verbindungen zeigten hoch Toxizität gegenüber Larven vonCulex quinquefaciatus in einer Dosierung von 1 mgl^–1.

     

<Superscript>90</Superscript>Y-DOTA-Lanreotide: A potential agent for targeted therapy

Several human tumors such as neuroendocrine tumors, medullary thyroid carcinoma, etc., express somatostatin receptors which specifically bind somatostatin and its analogues such as lanreotide, octreotide, etc. In order to prepare a therapeutic agent for targeting such tumors, attempts were made to prepare ⁹⁰Y-DOTA-Lanreotide. Lanreotide could be successfully conjugated with the macrocyclic chelating agent DOTA (1,4,7,10-tetraaza cyclododecane tetracetic acid) which forms stable complexes with ⁹⁰Y. ⁹⁰Y-DOTA-Lanreotide could be prepared in >98% radiochemical purity and remained stable for 72 hours at room temperature. The tracer showed specific binding to A431 cells. Biodistribution studies in C57BL6 mice bearing melanoma showed ∼1.3% uptake pergram of tumor at 24-hour p.i.     

胆红素在纳米TiO2膜上的吸附行为研究

采用石英晶体微天平现场技术,研究了胆红素在纳米TiO2表面的吸附动力学行为,并考察了溶液pH、硅烷亲脂性试剂及金属离子修饰的纳米TiO2对胆红素吸附的影响。结果表明,胆红素在纳米TiO2表面的吸附平衡常数K为2·0×106L/mol;由于亲水性纳米TiO2表面的羟基和胆红素分子中的羧基发生作用,胆红素吸附量随溶液pH增大而增大;但经过硅烷试剂亲脂性修饰后,吸附量随pH增大而下降;经过金属离子修饰后,改变了TiO2表面电荷导致吸附量增加,且吸附量随金属离子电荷增加而增加,当金属离子所带电荷相同时,吸附量基本相同。     

Sterically Congested Phosphite Ligands: Synthesis,crystallographic characterization,and observation of unprecedented eight-Bond 31P,31P coupling in the 31P-NMR spectra

The synthesis and characterization of 2-{1-{3,5-bis(1,1-dimethylethyl)-2-{[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosphepin-6-yl]oxy}phenyl}ethyl}-4,6-bis(1,1-dimethylethyl)phenyl diphenyl phosphite ( 6 ) is described. In the ³¹P-NMR spectrum (¹H-decoupled) of 6 , an unprecedented eight-bond P,P coupling of J = 72.8 Hz is observed. In the X-ray crystal structure of 6 , an intramolecular P–P distance of 3.67 Å is found, which is within the sum of the van-der-Waals radii of the P-atoms. The observed intramolecular P–P distance suggests that a through-space coupling mechanism is operative. The solid-state conformation of 6 is compared to the conformation obtained by semi-empirical MO geometry optimizations (PM3 method). The calculated geometry suggests that the solid-state structure is near a true energy minimum, but that crystal-packing forces decrease the intramolecular P–P distance in the solid state. In the absence of crystal-packing forces, however, the collisional and vibrational energy available in solution may lead to the population of states with a shortened intramolecular P–P distance in 6 . The proximity of the P-atoms in 6 is due to restricted conformational freedom resulting from steric congestion within the molecule. The free energy of activation (ΔG* = 10.2 and 10.8 kcal/mol for unequal populations of exchanging conformers) for ring inversion of the dibenzo[d,f][1,3,2]dioxaphosphepin ring in 6 is determined by variable-temperature ³¹P-NMR spectroscopy. Semi-empirical MO calculation on model compounds suggest that the structure of the transition state for ring inversion has the two aryl rings and O-atoms in a common plane, with the P-atom lying above this plane.     

Reaction of alpha-oxoketene-N,S-arylaminoacetals with Vilsmeier reagents: an efficient route to highly functionalized quinolines and their benzo/hetero-fused analogues

A simple, highly efficient, and regioselective synthesis of functionalized quinolines through Vilsmeier cyclization of a variety of alpha-oxoketene-N,S-anilinoacetals has been reported. The cyclization is found to be facile with N,S-acetals bearing strongly activating groups on aniline, whereas yields of quinolines are moderate in other cases. The reaction could also be extended for the synthesis of substituted tricyclic benzo[h]quinoline, pyrido[2,3-h]quinoline, 4,7-diphenylphenanthroline, and tetracyclic quino[8,7-h]quinoline by performing a Vilsmeier reaction on N,S-acetals derived from 1-naphthylamine, m-phenylenediamine, o-phenylenediamine, and 1,5-diaminonaphthalene, respectively. A few of the newly synthesized quinolines are subjected to further transformation to afford 2-unsubstituted (Raney-Ni/Ethanol), quinoline-5,8-quinone (NBS/H(2)SO(4)), or 2-alkyl/aryl aminoquinolines through sequential m-CPBA oxidation to the corresponding (2-methylsulfonyl)quinoline followed by replacement with appropriate amines. Similarly, cycloannulation of a few 2-methylthio-3-benzoylquinolines with hydrazine hydrate under microwave irradiation afforded the corresponding substituted and fused pyrazolo[3,4-b]quinolines in excellent yields, whereas TBTH/AIBN-mediated cyclization of the corresponding 3-(2-bromobenzoyl)-2-methylthioquinolines yielded the corresponding benzothiopyrano-fused quinolines through radical translocation.     

Adoption and use of AI tools: a research agenda grounded in UTAUT

This paper is motivated by the widespread availability of AI tools, whose adoption and consequent benefits are still not well understood. As a first step, some critical issues that relate to AI tools in general, humans in the context of AI tools, and AI tools in the context of operations management are identified. A discussion of how these issues could hinder employee adoption and use of AI tools is presented. Building on this discussion, the unified theory of acceptance and use of technology is used as a theoretical basis to propose individual characteristics, technology characteristics, environmental characteristics and interventions as viable research directions that could not only contribute to the adoption literature, particularly as it relates to AI tools, but also, if pursued, such research could help organizations positively influence the adoption of AI tools.