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21.
Preparation and characterization of the first derivatives of the fused macropolyhedral anion [B22H22]2− are reported. The species [B22H21OH]2− (1) and [B22H21OEt]2− (2) are obtained from workup of the products of the reaction between HgBr2 and [NBzlEt3]2[B22H22]; a cluster involving the conjoining of a closo-B12 icosahedron with a nido-B10 cluster. Washing the products with ethanol followed by thin-layer chromatography allows the isolation of 1 and 2, reproducibly, in yields of 27 and 20%, respectively. The species were characterized by NMR spectroscopy, elemental analysis and X-ray diffraction studies. The crystal structure determinations of the two species identify novel features. Apparently the influence of the O atoms in the ions [B22H21OH]2− and [B22H21OEt]2− results in the lengthening of what was a gunwale B---B connection adjacent to the junction of the two cages such that the distances are 2.180 and 2.230 Å, respectively. These latter are longer than the corresponding distance in the parent species [B22H22]2−, which is 2.09 Å; quite long for a normal B---B distance. Thus it is assumed that these B atoms, in 1 and 2, one of which bears the substituent, are not bonded to each other.  相似文献   
22.
中子成像作为一种快速、直观的无损检测技术,在核工业、航空航天、新能源、地质、考古、先进制造等多个领域得到广泛应用。中子成像利用中子不带电、穿透能力强、对轻元素敏感、可区分同位素和近邻元素等特性,非常适合开展含氢元素、近邻元素和同位素等材料的无损检测。本文概述了中子成像技术的基本原理及特点,并结合中国先进研究堆(CARR)中子成像装置上的应用案例, 重点介绍了国内外中子成像技术在储氢材料、燃料电池、岩石、核燃料元件、古代文物等领域的典型应用。随着中子成像技术的不断发展和广泛应用,有望为我国更多领域研究提供更强有力的技术支撑。  相似文献   
23.
(1) Background: Due to human activities, greenhouse gas (GHG) concentrations in the atmosphere are constantly rising, causing the greenhouse effect. Among GHGs, carbon dioxide (CO2) is responsible for about two-thirds of the total energy imbalance which is the origin of the increase in the Earth’s temperature. (2) Methods: In this field, we describe the development of periodic mesoporous organosilica nanoparticles (PMO NPs) used to capture and store CO2 present in the atmosphere. Several types of PMO NP (bis(triethoxysilyl)ethane (BTEE) as matrix, co-condensed with trialkoxysilylated aminopyridine (py) and trialkoxysilylated bipyridine (Etbipy and iPrbipy)) were synthesized by means of the sol-gel procedure, then characterized with different techniques (DLS, TEM, FTIR, BET). A systematic evaluation of CO2 adsorption was carried out at 298 K and 273 K, at low pressure. (3) Results: The best values of CO2 adsorption were obtained with 6% bipyridine: 1.045 mmol·g−1 at 298 K and 2.26 mmol·g−1 at 273 K. (4) Conclusions: The synthetized BTEE/aminopyridine or bipyridine PMO NPs showed significant results and could be promising for carbon capture and storage (CCS) application.  相似文献   
24.
The current paper deals with the development of a new biologically active food supplement (BAFS) aimed at treating atherosclerosis. Since atherosclerosis is considered to be a disease of aging, the composition of the supplement includes such essential minerals as magnesium and potassium, which are commonly used to prevent atherosclerosis, as well as vitamins C, E and the B-group vitamins in order to address the needs of the elderly. The authors outline the supplement-manufacturing technology and discuss the clinical trial undertaken by patients, aged about 60 years, with peripheral atherosclerosis. The research methodology focuses on studying the effectiveness of the developed supplement by assessing the influence of the active ingredients on treating metabolic disorders. To establish the efficacy of the supplement, blood tests, ultrasound and physical examinations were applied. The combination therapy resulted in improved metabolism and an overall better performance of the cardiovascular system; therefore, the BASF can be recommended as part of combination therapy to prevent and treat atherosclerotic and age-related changes in blood vessels.  相似文献   
25.
Radioligand therapy (RLT) is an emergent drug class for cancer treatment. The dose administered to cancer patients is constrained by the radiation exposure to normal tissues to maintain an appropriate therapeutic index. When a radiopharmaceutical or its radiometabolite is retained in the kidneys, radiation dose deposition in the kidneys can become a dose-limiting factor. A good exemplar is [177Lu]Lu-DOTATATE, where patients receive a co-infusion of basic amino acids for nephroprotection. Besides peptides, there are other classes of targeting vectors like antibody fragments, antibody mimetics, peptidomimetics, and small molecules that clear through the renal pathway. In this review, we will review established and emerging strategies that can be used to mitigate radiation-induced nephrotoxicity, with a focus on the development and incorporation of cleavable linkers for radiopharmaceutical designs. Finally, we offer our perspectives on cleavable linkers for RLT, highlighting future areas of research that will help advance the technology.  相似文献   
26.
As a rising star among porous solid materials, covalent organic frameworks(COFs) with excellent properties including but not limit to facilely controllable structure, high porosity, and multi-chemical functionality represent significant potential for efficient 127Xe/85Kr capture and separation. In this study, through tuning the length of the organic ligands, two-dimensional(2D) COF mate-rials with identical connection group but different pore properties, denoted as ATFG-COF and TpPa-COF with AA-stacking model and TpBD-COF with AB-stacking model were synthesized and tested for Kr and Xe adsorption for the first time. Adsorption measurements indicate that the narrower pore apertures and higher porosity are conducive for COF materials to capture Xe and Kr. Furthermore, the Henry's constant, isosteric heat of adsorption(Qst), and ideal adsorbed solution theory(IAST) selectivity of ATFG-COF, the pore size of which is closest to the kinetic diameter of the Xe atom(0.41 nm) among 2D COF materials, were carried out based on the single component sorption isotherms. The results illustrate that the high isosteric heat values of Xe/Kr adsorption on ATFG-COF are 25 and 16 kJ/mol at room temperature, respectively. Henry's law predicts that the selectivity factor of Xe to Kr is 6.07, consistent with the adsorption selectivity(ca. 6) calculated based on the IAST.  相似文献   
27.
N Durgaprasad  M V S Rao 《Pramana》1978,10(2):131-141
An alternate and a new interpretation is given for the event attributed to a magnetic monopole by Price and coworkers found in an emulsion plastic sandwich stack flown from Sioux City, Iowa, USA on 18 September 1973. The electron pick-up and stripping cross-sections of nuclei ofZ∼70–80 andv∼0.6–0.7c in Lexan polycarbonate are calculated using the formulae given by Nikolaev. It is shown that the corresponding mean free paths are of the order of thickness (∼250μ) of Lexan plastic sheets used by them. In such a case asnapshot of these processes is believed to have been observed in plastic sheets. Monte-Carlo simulations of the event have been made for three values of charges at the top of the main Lexan stack, namelyZ=83, 78 and 70 respectively. The event is thus interpreted as a cosmic ray nucleus ofZ=70–83 andv=0.6–0.7c losing and capturing electrons (mainly the latter) as it passes through the stack. The probability of the occurrence of such an event is estimated by several methods.  相似文献   
28.
29.
用国内近年新研制的CeF3闪烁体和常用闪烁体ST401分别配特性相同的光电倍增管,构成两种闪烁体探测器,在强度不随时间变化的DD中子源场中测量了这两种闪烁探测器的相对灵敏度,测量结果表明:CeF3闪烁探测器对DD中子的灵敏度比同尺寸ST401的灵敏度低一个量级以上。  相似文献   
30.
Es wird eine Anordnung beschrieben, die es gestattet, bis zu 7 Proben unter identischen Bedingungen rotationssymmetrisch zu aktivieren. Die Proben rotieren um zwei parallele Achsen. Es wird über Erprobungsmessungen durch Aktivierung von Cu-und N-haltigen Proben berichtet.  相似文献   
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