Optimization of Oxygen Parameters for Determination of Carbon and Nitrogen in Biochar Materials

Recently, there has been increased focus on biochar materials due to their ability to sequester carbon for long-term in soil. In the production of biochar or charcoal, plant biomass is heated in a low or no oxygen environment. This process results in a product with unique characteristics. But there is limited research on the standardization of methods for determining total carbon (C) and nitrogen (N) in the biochar materials whose properties vary by feedstock type and pyrolytic conditions. The objective of this study was to determine the oxygen dosing time (OT) and dose (OD) for total organic carbon (TC) and nitrogen (TN) analysis in biochar materials by dry combustion method (using Vario Max CNS analyzer). Central composite rotatable design was used to determine the effect of five levels of oxygen dosing time (OT) and dosing level (OD) on measurement of total carbon and total nitrogen in four types of plant originated biochars. OT and OD level interaction had significant impact on the measurement of TC and TN in all types of biochar materials. Optimum levels of OT and OD were determined as 103 to 110 sec and 180 to 232 ml/min, respectively.     

Solid-state structure of (+)-phendimetrazine bitartarate,an anorexic drug

The anorexic drug (+)-(2S, 3S, 4S)-phendimetrazine-2R, 3R)-bitartarate crystallized in the orthorhombic space groupP2₁2₁2₁ and at 293 Ka=7.7710(4),b=13.1379(7),c=15.9913(9) Å,V=1632.6(2) ų,Z=4,R(F)=0.062, andR _w (F)=0.026. A chair conformation 2,3-trans-1,4-oxazine ring with equatorially oriented 2-phenyl,3-methyl, andN-methyl substituents was found as predicted by an earlier reported solid-state CP-MAS¹³C-NMR investigation of crystalline (±)-phendimetrazine bitartarate. The O-CH₂-CH₂-N torsion angle of –58.4(6)° in the solid-state agrees nicely with the 56.0(7)° dihedral angle value estimated by¹H NMR spectroscopy for the major (equatorialN-methyl) phendimetrazine mesylate species in CD₂Cl₂ solution. A common solid-state conformational arrangement was found for (+)-phendimetrazine and a series of six other anorexic drugs structurally analogous to (+)-(2S, 3S)-pseudoephedrine. In this arrangement, NCH(Me)CPh has (S)-configuration, there is a (–)-gaucheMe-CH-C-Ph torsion angle, an antiperiplanarN-CH-C-Ph torsion angle, and the phenyl ring approximately eclipses the C-H bond of the attached carbon (e.g., H-C-C_ipso-C_ortho ca. 4° for 2,3-transphendimetrazine). Nonbonded interactions involving the 3-methyl and the 2-phenyl groups open up the H-C-C_ipso-C_ortho angle in a series of solid-state structures containing the epimeric (–)-(2R, 3S)-ephedrine moiety (e.g., ca. 45° for molecular mechanics calculated 2,3-cis-phendimetrazine model).     

基于UKF的INS/GNSS/CNS组合导航最优数据融合方法

为了提高INS/GNSS/CNS组合系统的导航精度,提出了一种基于UKF的多传感器最优数据融合方法。该方法具有两层融合结构,第一层中,GNSS和CNS分别通过两个局部UKF滤波器与INS组合,以并行的方式获得INS/GNSS和INS/CNS子系统的局部最优状态估值;第二层中,根据线性最小方差准则推导出一种矩阵加权数据融合算法,对局部状态估值进行融合,获取系统状态的全局最优估计。提出的方法无需采用方差上界技术对局部状态进行去相关处理,克服了联邦卡尔曼滤波(FKF)及其优化形式存在的缺陷。仿真结果表明,相比于FKF,提出方法的导航精度可至少提高36.4%;相比于UKF-FKF,其导航精度也可至少提高21.0%。     

The Preparation of 2‐Arylmethylidene‐8‐methyl‐8‐azabicyclo[3.2.1]octan‐3‐ones

Abstract

An efficient and versatile two‐step synthesis of 2‐arylmethylidene‐8‐methyl‐8‐azabicyclo[3.2.1]octane‐3‐ones, via mono aldol condensation of tropinone with a variety of aryl aldehydes followed by pTsOH‐catalyzed dehydration, is described.     

On the stability of the three classes of Newtonian three-body planar periodic orbits

Currently,the fifteen new periodic orbits of Newtonian three-body problem with equal mass were found by Suvakov and Dmitra sinovi[Phys Rev Lett,2013,110:114301]using the gradient descent method with double precision.In this paper,these reported orbits are checked stringently by means of a reliable numerical approach(namely the"Clean Numerical Simulation",CNS),which is based on the arbitrary-order Taylor series method and data in arbitrary-digit precision with a procedure of solution verification.It is found that seven among these fifteen orbits greatly depart from the periodic ones within a long enough interval of time,and are thus most possibly unstable at least.It is suggested to carefully check whether or not these seven unstable orbits are the so-called"computational periodicity"mentioned by Lorenz in 2006.This work also illustrates the validity and great potential of the CNS for chaotic dynamic systems.     

The irritable larynx syndrome

Muscular tension dysphonia, episodic laryngospasm, globus, and cough may be considered to be hyperfunctional laryngeal symptoms. Suggested etiological factors for these symptoms include gastroesophageal reflux, psychological problems, and/or dystonia. We propose a unifying hypothesis that involves neural plastic change to brainstem laryngeal control networks through which each of the above etiologies, plus central nervous system viral illness, can play a role. We suggest that controlling neurons are held in a "spasm-ready" state and that symptoms may be triggered by various stimuli. Inclusion criteria for the irritable larynx syndrome are episodic laryngospasm and/or dysphonia with or without globus or chronic cough; visible or palpable evidence of tension or tenderness in laryngeal muscles; and a definite symptom-triggering stimulus. thirty-nine patients with irritable larynx syndrome were studied. Gastroesophageal reflux was felt or proven to play a major role in a large number of the group (>90%), and about one third were deemed to have psychological causative factors. Viral illness seemed quite prevalent, with one third of patients able to relate the onset of symptoms to a viral illness that we feel might lead to central nervous system changes. Our proposed hypothesis includes a mechanism whereby acquired plastic change to central brainstem nuclei may lead to this form of hyperkinetic laryngeal dysfunction. It gives structure and reason to an array of therapy measures and suggests direction for basic research.     

空天飞行器SINS/CNS深组合导航算法(英文)

空天飞行器往返于大气层内外,持续工作时间长。捷联惯性/天文组合导航自主性强、隐蔽性好,是最适合空天飞行器的导航方式之一。为提高传统天文定位的导航精度和可靠性,解决其在机载应用中水平基准制约的问题,分析了平台误差角和位置误差对高度角量测的影响,提出了一种以天体高度角为量测信息的捷联惯性/天文深组合导航算法。该算法采用卡尔曼滤波器进行最优估计,可有效估计并补偿系统的姿态误差,减少天文导航定位对水平基准的依赖。仿真表明,单星观测条件下,导航系统姿态误差快速收敛,定位的均方根误差在200 m以内,且系统导航性能随导航星数量的增加而提高。     

抗差自适应插值粒子滤波及其在组合导航中的应用

针对粒子滤波存在的粒子退化和重要性密度函数难以选取的问题,在吸收抗差自适应滤波、二阶插值滤波和粒子滤波算法优点的基础上,提出了一种新的抗差自适应插值粒子滤波算法。该算法利用二阶插值滤波算法得到重要性密度函数,通过抗差自适应因子实时控制动力学模型误差及观测异常对导航解的影响。将该算法应用于SINS/CNS/SAR组合导航系统进行计算仿真,并与经典的粒子滤波算法进行比较分析。结果表明,提出的滤波算法得到的姿态误差控制在[-0.3′,+0.3′],速度误差控制在[-0.4 m/s,+0.4 m/s],位置误差控制在[-5 m,+5 m],性能明显优于经典的粒子滤波算法。新的滤波算法不但能够有效地抑制粒子退化,而且能够有效地控制动力学模型误差及观测异常的影响,提高了组合导航的滤波精度。     

Identification of an Orally Bioavailable,Brain-Penetrant Compound with Selectivity for the Cannabinoid Type 2 Receptor

Modulation of the endocannabinoid system (ECS) is of great interest for its therapeutic relevance in several pathophysiological processes. The CB2 subtype is largely localized to immune effectors, including microglia within the central nervous system, where it promotes anti-inflammation. Recently, a rational drug design toward precise modulation of the CB2 active site revealed the novelty of Pyrrolo[2,1-c][1,4]benzodiazepines tricyclic chemotype with a high conformational similarity in comparison to the existing leads. These compounds are structurally unique, confirming their chemotype novelty. In our continuing search for new chemotypes as selective CB2 regulatory molecules, following SAR approaches, a total of 17 selected (S,E)-11-[2-(arylmethylene)hydrazono]-PBD analogs were synthesized and tested for their ability to bind to the CB1 and CB2 receptor orthosteric sites. A competitive [³H]CP-55,940 binding screen revealed five compounds that exhibited >60% displacement at 10 μM concentration. Further concentration-response analysis revealed two compounds, 4k and 4q, as potent and selective CB2 ligands with sub-micromolar activities (K_i = 146 nM and 137 nM, respectively). In order to support the potential efficacy and safety of the analogs, the oral and intravenous pharmacokinetic properties of compound 4k were sought. Compound 4k was orally bioavailable, reaching maximum brain concentrations of 602 ± 162 ng/g (p.o.) with an elimination half-life of 22.9 ± 3.73 h. Whether administered via the oral or intravenous route, the elimination half-lives ranged between 9.3 and 16.7 h in the liver and kidneys. These compounds represent novel chemotypes, which can be further optimized for improved affinity and selectivity toward the CB2 receptor.     

锌-硫氰酸铵还原体系用于氢化偶氮苯的合成

氢化偶氮苯是重要的精细有机化工原料及中间体,染料工业用于制备联苯胺染料,医药工业用于生产解热镇痛药保泰松等[1]。传统的制备方法是在强碱性介质中用锌粉还原硝基苯,反应时间长,产率低[2]。用硫化铵快速还原偶氮苯生成氢化偶氮苯[3],则硫化铵用量大,刺激性气味对操作者及环境造成极大危害。我们采用ＮＨ4ＣＮＳ的饱和溶液与锌粉组成还原体系,在25℃时还原偶氮苯,反应条件温和,锌粉用量少,时间短,产率高,操作简单。反应方程式如下:ＰｈＮ=ＮｐＨ(橙红色)Ｚｎ-ＮＨ4ＣＮＳ25℃,ＥｔＯＨＰｈＮＨＮＨＰｈ(白色)1　实验部分在50ｍｌ圆底…