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11.
Yu. Arestov A. Borovikov E. Kozlovsky A. Minaenko A. Moiseev C. Cochet D. Denegri C. Lewin M. A. Turluer U. Gensch H. J. Grabosch W. Lohmann J. MacNaughton France-USSR Collaboration CERN-USSR Collaboration 《Zeitschrift fur Physik C Particles and Fields》1981,8(4):283-289
New data on the inclusive production of the non-strange resonances ?0(770), ω(783), ?(1020) andf(1270) inK ? p interactions at 32 GeV/c are presented. The inclusive production cross sections are equal to (4.32±0.72) mb, (3.7±1.4) mb, (0.65±0.10) mb and (0.91±0.35) mb respectively. Estimates of the topological cross sections are also obtained. The invariant and non-invariantx-distributions for the vector mesons ?0 and ? indicate the prevalence of forward resonance production in the c.m. system. For the tensorf-meson the rapidity andx-distributions are presented. Thet′-distributions for ?0, ?, andf have exponential slopes of 0.6±0.1 GeV?2, 1.2±0.2 GeV?2, and 0.8±0.5 GeV?2 respectively. The exponential slope ofp T 2 -distribution of thef-meson is equal to (2.3±0.5) GeV?2. 相似文献
12.
Israel Zilbermann Avraham Meshulam Haim Cohen Dan Meyerstein 《Supramolecular chemistry》2013,25(2):325-332
Abstract The mechanisms and kinetics of oxidation of ascorbate, AH?, by Ni(III)Li aq and by LiNi(III) (HPO4)2 ? complexes (L1 = meso-(5,12)-7,7,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane; L2 = 1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane) in neutral aqueous solutions have been investigated. The oxidation of ascorbate by the LiNi(III) (HPO4)2 ? and Ni(III)L1 aq proceeds via two consecutive reactions well separated in time. The products of the first reaction are the A.? radical anion and the corresponding Ni(II) complex. The oxidations by the LiNi(III)(HPO4)2 ? complexes proceed via the outer sphere mechanism, whereas the detailed mechanism of reaction of Ni(III)L1 aq cannot be determined. The rate of reaction decreases with the increase in the concentration of phosphate, thus indicating that LiNi(III)(HPO4)(H2O)+ and LiNi(III)OH2+ are stronger oxidizing agents than LiNi(III)(HPO4)? 2. The oxidation of ascorbate by Ni(III)L2 aq proceeds via three consecutive reactions which are well separated in time. Thus the results clearly point out that this process occurs via the inner sphere mechanism. The first transient observed is tentatively identified as L2(H2O)Ni(II)(A.?)2+, i.e., an unexpected complex of the ascorbate anion radical. Also in this process the last transient observed is the A.? anion radical. The stabilization of the ascorbyl radical in a transient complex might be of biological significance. 相似文献
13.
A short and straightforward synthesis of DAMGO is described. 相似文献
14.
Nicholas J. Youngman Matthew R. Lewin Rebecca Carter Arno Naude Bryan G. Fry 《Molecules (Basel, Switzerland)》2022,27(5)
Snakebite remains a significant public health burden globally, disproportionately affecting low-income and impoverished regions of the world. Recently, researchers have begun to focus on the use of small-molecule inhibitors as potential candidates for the neutralisation of key snake venom toxins and as potential field therapies. Bitis vipers represent some of the most medically important as well as frequently encountered snake species in Africa, with a number of species possessing anticoagulant phospholipase A2 (PLA2) toxins that prevent the prothrombinase complex from inducing clot formation. Additionally, species within the genus are known to exert pseudo-procoagulant activity, whereby kallikrein enzymatic toxins cleave fibrinogen to form a weak fibrin clot that rapidly degrades, thereby depleting fibrinogen levels and contributing to the net anticoagulant state. Utilising well-validated coagulation assays measuring time until clot formation, this study addresses the in vitro efficacy of three small molecule enzyme inhibitors (marimastat, prinomastat and varespladib) in neutralising these aforementioned activities. The PLA2 inhibitor varespladib showed the greatest efficacy for the neutralisation of PLA2-driven anticoagulant venom activity, with the metalloproteinase inhibitors prinomastat and marimastat both showing low and highly variable degrees of cross-neutralisation with PLA2 anticoagulant toxicity. However, none of the inhibitors showed efficacy in neutralising the pseudo-procoagulant venom activity exerted by the venom of B. caudalis. Our results highlight the complex nature of snake venoms, for which single-compound treatments will not be universally effective, but combinations might prove highly effective. Despite the limitations of these inhibitors with regards to in vitro kallikrein enzyme pseudo-procoagulant venom activity, our results further support the growing body of literature indicating the potential use of small molecule inhibitors to enhance first-aid treatment of snakebite envenoming, particularly in cases where hospital and thus antivenom treatment is either unavailable or far away. 相似文献
15.
We address the problem of scheduling in programs involving the production of multiple units of the same product. Our study was motivated by a construction program for fast naval patrol boats. Other applications of this problem include procurement of multiple copies of aircraft, spacecraft, and weapon systems. In this problem we must decide how many units of the product to assign to each of a number of available crews (individuals, teams, subcontractors, etc.). These types of problems are characterized by two potentially conflicting considerations: 1) the need to complete each unit by its contractual due date, and 2) learning effects. Because of the first consideration, there is a tendency to use multiple crews for simultaneous production, so that meeting due dates is assured. However, the second consideration encourages assigning many units to a single crew so that learning effects are maximized. We study this scheduling problem with two different penalty cost structures and develop models for both versions. The models trade-off the penalty associated with late deliveries and the savings due to learning (and possibly incentive payments for early completion). We discuss different heuristic algorithms — simulated annealing, a genetic algorithm, and a pair-wise swap heuristic — as well as an exhaustive search to determine a baseline for comparisons. Our computational results show that the pair-wise swap algorithm is the most efficient solution procedure for these models. 相似文献
16.
Mordecai Lewin 《Journal of Combinatorial Theory, Series A》1974,16(2):131-146
Subsets of a Cartesian product X × Y, where X and Y are arbitrary sets, are considered as a generalization of incidence matrices. Minimal cover, essential set etc. are introduced in a stronger sense and their properties discussed. The existence of a minimal cover for an arbitrary generalized incidence matrix is proved. As an application a previous result is extended. 相似文献
17.
Suzuki Y Sarachik MP Chudnovsky EM McHugh S Gonzalez-Rubio R Avraham N Myasoedov Y Zeldov E Shtrikman H Chakov NE Christou G 《Physical review letters》2005,95(14):147201
Local time-resolved measurements of fast reversal of the magnetization of single crystals of Mn12-acetate indicate that the magnetization avalanche spreads as a narrow interface that propagates through the crystal at a constant velocity that is roughly 2 orders of magnitude smaller than the speed of sound. We argue that this phenomenon is closely analogous to the propagation of a flame front (deflagration) through a flammable chemical substance. 相似文献
18.
Knowing the low-frequency response of hydrophones, down to 100 kHz at least, is important for accurate biomedical ultrasound measurements. However, current international standards do not extend below 500 kHz. Furthermore, commercial hydrophone sources typically do not supply sensitivity data below 1-2 MHz. Therefore, to help identify and validate practical calibration methods below 2 MHz, the authors have extended their previous individual efforts in an interlaboratory evaluation of sensitivity calibration using the swept-frequency technique, time delay spectrometry (TDS). Calibrations were performed for needle and membrane PVDF hydrophones using each laboratory's TDS system. Each site employed the same purpose-built broadband source transducers, comprising both plano-concave and biconcave 1-3 piezocomposite elements 4 cm in diameter, with maximum and minimum thicknesses of approximately 1.5 and 0.1 cm. Agreement between laboratories was within the estimated measurement precision of +/-0.6 dB. The results demonstrated that a TDS system employing such transducers constitutes a viable method for hydrophone calibrations in this frequency range. 相似文献
19.
To facilitate the implementation and verification of the new ultrasound hydrophone calibration techniques described in the companion paper (somewhere in this issue) a nonlinear propagation model was developed. A brief outline of the theoretical considerations is presented and the model's advantages and disadvantages are discussed. The results of simulations yielding spatial and temporal acoustic pressure amplitude are also presented and compared with those obtained using KZK and Field II models. Excellent agreement between all models is evidenced. The applicability of the model in discrete wideband calibration of hydrophones is documented in the companion paper somewhere in this volume. 相似文献
20.
(+)-Cocaine has been prepared from commercially available 3-tropinone in four steps. Synthetic procedures and experimental details are provided. 相似文献