分子亲脂-亲水性的量子化学描述(Ⅰ)——分子的亲脂和亲水表面

给出基于分子结构的“启发式”亲脂-亲水势HMLP(Heuristic molecular lipophilicity-hydrophilicity potential)的理论分析和有说服力的算例.用量子化学计算其分子表面的静电势V(r)的分布,通过与周围原子表面静电势的比较,构造表达分子静电势的极性和大小的函数L(r).亲脂势L(r)保留了静电势V(r)描述分子静电作用的能力,并把应用范围扩展到疏水性的描述.HMLP不使用原子的经验参数,但在L(r)的构造中使用了经验的函数形式.经参数化和指标化后,HMLP有望用于蛋白质结构与功能的研究和药物分子配体与生物大分子受体结合自由能的估算.     

三(2-苯并咪唑亚甲基 )胺合钴(Ⅱ)配合物的合成和分子结构

三 (2-苯并咪唑亚甲基 )胺 (NTB)与氯化钴(Ⅱ)在乙醇中反应生成配合物 C_(24)H_(21)N_7CoCl。在二甲亚砜溶剂中,经缓慢挥发获得其单晶 Co(NTB)Cl· 3[(CH_3)_2SO]。晶体属三斜晶系,空间群 P-1,a=0.9678(3), b=1.1780(5),c=1.6102(9)nm,α=71.07(8),β=89.27(8),γ=84.81(3)° ,V=1.729(2)nm~3,Z=2,Dc=1.408g· cm~(－3),Mr=733.24,F(000)=762,μ =0.7864mm~(－ 1)。用 1825个 I≥ 3σ (I)的独立衍射点进行结构解析与修正,最终偏离因子 R=0.068, Rw=0.072。晶体中 Co(Ⅱ)与 NTB上的四个 N原子及一个氯离子配位,形成一个五配位的轻微扭曲的三角双锥构型。     

磺化苯膦酸锆的制备及其催化酯化反应研究

以苯和三氯化磷等小分子化合物为原料,合成制备了固体酸催化剂磺化苯膦酸锆,用红外光谱、Ｘ－射线衍射方法对其结构表征,并研究其在酯化应中的催化活性。实验结果表明：磺化苯膦酸锆是一种具有层状结构的活性较高的固体酸催化剂,乙酸丁酯,氯乙酸丁酯反应温度控制在１１０～１２０℃,产物收率在８０％以上,催化剂重复使用多次后用稀酸浸泡可恢复活性。     

带对流项的渗流型方程的显格式

１．引言　假设有一种不可压流体在一均匀的、各向同性的刚性多孔柱形介质中流动,流动沿着与水平方向成ａ角进行,则可用下述方程描述其中λ＝ｓｉｎα,ｕ表示介质的含湿度．λ＝０,即表示沿水平方向流动,它和λ≠０的情形分别称为无对流项和有对流项的渗流方程．它们可分别写成下面一般的形式：　渗流型方程是退化抛物型方程,由于它可有退化点（使二阶导数项系数为零的点）,它与正规抛物型方程有很大区别．正规抛物型方程有充分光滑的古典解,渗流方程则不然．即使初值充分光滑,也不能保证渗流方程有光滑的解．实际上,渗流方程可有…     

Mn替代对Dy2AlFe16－xMnx化合物的结构和磁性的影响

通过X射线衍射及磁测量手段研究了Dy₂AlFe_16-xMn_x化 合物的结构和磁性.研究结果表明Dy₂AlFe_16-xMn_x化合 物具有六角相的Th₂Ni₁₇型结构.对x=1，2的样品采用X射线热膨胀 测定法在104—647K的温度范围内测量了其热膨胀性质，发现这些化合物在低温下存在热膨 胀反常现象，在居里点附近出现负膨胀性质.对自发磁致伸缩的研究结果表明Dy₂AlFe_16-xMn_x化合物中存在着较强的各向异性的自发磁致伸缩，随 着Mn含量的增加，其低温下的自发体磁致伸缩减弱.磁测量结果表明Mn的替代导致Dy_{2< /sub>AlFe16-xMnx化合物的居里温度及自发磁化强度急剧下降. 关键词： 2}AlFe_16-xMn_x化合物')" href="#">Dy₂AlFe_16-xMn_x化合物 反常热膨胀 自发磁致伸缩 自发磁化强度     

Dy2 AlFe13 Mn3 化合物的本征磁致伸缩

通过X-射线衍射及磁测量手段研究了Dy2AlFe13Mn3化合物的结构及磁性质。研究结果表明Dy2AlFe13Mn3化合物具有六角相的Th2Ni17型结构。通过X-射线热膨胀测定法发现Dy2AlFe13Mn3化合物在245到344K的温度范围内存在负热膨胀现象，其平均热膨胀系数为α＝-1.1×10-4K-1K-1。在105到360K的温度范围内，通过比较磁性状态下的晶胞参数和由高温顺磁状态外延得到的低温顺磁状态下的晶胞参数间的差别计算了Dy2AlFe13Mn3化合物的本征磁致伸缩。结果表明Dy2AlFe13Mn3化合物的本征体磁致伸缩ωS在105到245K的温度范围内随着温度的升高而增大，由105K时的7.0×10-3 增加到245K时的9.1×10-3。随着温度的进一步升高，ωS反而减小。沿c轴方向的本征线磁致伸缩λc随着温度的升高而减小。基面内的本征线磁致伸缩λa在105到270K的温度范围内随着温度的升高而增大，从105K时的0.8×10-3增大到270K时的3.4×10-3，然后随着温度的进一步升高而减小。     

New multidentate heteroscorpionate ligands: N-Phenyl-2,2-bis(pyrazol-1-yl)thioacetamide and ethyl 2,2-bis(pyrazol-1-yl)dithioacetate as well as their derivatives

New multidentate heteroscorpionate ligands, N-phenyl-2,2-bis(3,5-dimethylpyrazol-1-yl)thioacetamide PhHNCSCH(3,5-Me₂Pz)₂ (1), N-phenyl-2,2-bis(3,4,5-trimethylpyrazol-1-yl)thioacetamide PhHNCSCH(3,4,5-Me₃Pz)₂ (2), and ethyl 2,2-bis(3,5-dimethylpyrazol-1-yl)dithioacetate EtSCSCH(3,5-Me₂Pz)₂ (8), have been synthesized and their coordination chemistry studied. These heteroscorpionate ligands can act as monodentate, bidentate, or tridentate ligands, depending on the coordinate properties of different metals. Reaction of W(CO)₆ with 1 or 2 under UV irradiation yields monosubstituted carbonyl tungsten complexes W(CO)₅L (L = 1 or 2), in which N-phenyl-2,2-bis(pyrazol-1-yl)thioacetamide acts as a monodentate ligand by the s-coordination to the tungsten atom. In addition, these monosubstituted tungsten complexes have also been obtained by heating ligand 1 or 2 with W(CO)₅THF in THF. While similar reaction of Fe(CO)₅ with 1, 2, or 8 under UV irradiation results in tricarbonyl iron complexes PhHNCSCH(3,5-Me₂Pz)₂Fe(CO)₃ (5), PhHNCSCH(3,4,5-Me₃Pz)₂Fe(CO)₃ (6), and EtSCSCH(3,5-Me₂Pz)₂Fe(CO)₃ (9), respectively, in which N-phenyl-2,2-bis(pyrazol-1-yl)thioacetamide or ethyl 2,2-bis(pyrazol-1-yl)dithioacetate acts as a bidentate ligand through one pyrazolyl nitrogen atom and the CS π-bond in an η²-C,S fashion side-on bonded to the iron atom to adopt a neutral bidentate κ²-(π,N) coordination mode. Treatment of the lithium salt of 1 with Co(ClO₄)₂ · 6H₂O gives complex [PhNCSCH(3,5-Me₂Pz)₂]₂Co(ClO₄) with the oxidation of cobalt(II) to cobalt(III), in which N-phenyl-2,2-bis(3,5-dimethylpyrazol-1-yl)thioacetamide acts as a tridentate monoanionic κ³-(N,N,S) chelating ligand by two pyrazolyl nitrogen atoms and the sulfur atom of the enolized thiolate anion.     

Integrated wireless communications and wireless power transfer: An overview

As an important application of the fifth generation (5G) mobile communication systems, Internet of Things (IoT) has attracted worldwide research interests. Since most of the communication devices in IoT are powered by batteries, these devices always have limited operation time. Wireless power transfer (WPT) technology, which can transfer power over a wireless medium (without any wires), can avoid the need to manually replace or recharge the batteries of the wireless devices in IoT. For electromagnetic (EM) radiation-based WPT, since radio-frequency (RF) signals that transport energy can at the same time be used for wireless communications, integrated wireless communications and WPT becomes a new research area which has attracted great research interests. In this paper, we first introduce two main research paradigms for integrated wireless communications and WPT, i.e., simultaneous wireless information and power transfer (SWIPT) and wireless-powered communication network (WPCN). Then we provide an overview of the state-of-the-art of both SWIPT and WPCN, respectively. Finally, we point out the new and challenging future research direction.     

Multi-level quantization and blind equalization based direct transmission method of digital baseband signal

The direct transmission of digital baseband signals has practical significance in the field of Ethernet terminal connection, high-speed digital communication, data transmission of various types of information peripherals. The signal amplitude gradually decays while the transmission distance increases. Also the attenuation is proportional to the signal frequency, resulting in signal distortion and receiving error. It is a common method for digital baseband signal transmission to use pre-emphasis chip and equalizer chip to improve the transmission quality with a wide range of mature applications. This paper describes a new type of digital signal transmission method, as the receiver using analog-to-digital converter, instead of equalizer chip, to achieve the multi-level quantization of receiving time-domain data waveform. The waveform of the transmitted digital high and low level signal is sampled into multi-bit values. Then, the paper realizes adaptive frequency domain equalization based on soft threshold and makes use of multi-level quantization soft information for error correction. Error correcting code is mainly used to correct the error caused by the channel bandwidth limit, external noise or interference in the process of data transmission, so as to improve the stability and reliability of the transmission. The paper uses the two-stage error correcting codec system based on both Turbo and BCH coding, to achieve the high performance of Turbo code, and good characters of respond time and complexity. The transmitter outputs 12.5 MHz pseudo-random sequence through a 199.93 meter unshielded balanced twisted pair transmission medium. And the receiver circuit using a 62.5MSPS analog-to-digital converter over-samples the waveform to 8-level quantity. The output error of a 65536 bit pseudo-random sequence is less than 8 bits, and the error correction can be further improved by 8b-10b codec. Compared with the traditional pre-emphasis and balanced interface ICs connection, the method described in this article has the advantages of longer transmission distance, better flexibility and wider scope of use.