Isotopic Effects on Stereodynamics for Ca＋HCI, Ca＋DCI, and Ca＋TCl Reactions

The vector correlations in Ca＋HCl, Ca＋DCl, and Ca＋TCl reactions have been investigated by means of the quasi-classical trajectory calculations on PES constructed by means of multireference configuration interaction. The distributions of P（θr）, P（Фr） and the PDDCSs of （2π/σ）（dσ00/dωt）, （2π/σ）（dσ20/dωt）, （2π/σ）（dσ22＋/dωt）, （2π/σ）（dσ21-/dωt） have been calculated based on the surface. The remarkable isotopic effects in the reactions are observed, and the mechanism which may be ascribed to different mass factors is discussed.

Discussion on Green Development of Fenlong for Yield Increase, Quality Enhancing, Water Retaining and Multiple Use of Natural Resources

Fenlong green ecological agriculture technology （Fenlong technology）, a new smash ridging farming method developed by Guangxi Academy of Agdcultural Sciences, has been elected as the recommended cultivation technique by the Ministry of Agriculture of China. It replaces the traditional plowshare with spiral drill, and its tilth depth is twice deeper than that by tractor tilthing. It also extends soil nutrient, moisture, oxygen and microorganism, the so-called ＂Four pools＂. Soil nutrient, oxygen, microorganism, light and rainfall use ratio is increased by 10%-100%, creating a platform for natural increase of more than 10% of crop yield. Its application to over 20 kinds of crops in 21 provinces has proved that the yield increases 10-30% with quality enhancing 5% and double water retaining capacity but no more input. When the application area of Fenlong could reach 67 million hm2, the amount of fertilizer can be reduced by 40-50 billion kg, saving 120-150 billion Yuan. In this paper, we put forward the strategy of ＂4＋1＂ （arable, saline-alkali soil, grasslands, Sponge City ＋ rivers） green development in China, and deepened the Fenlong cultivated tilled layer from 16.5 cm to 35 cm for 67 million hm2 arable land, ridged 13.3 million hm2 of saline-alkali soil for 35 cm, and also 35 cm for 67 million hm2 degraded steppe, which could have the following 3 effects： first, the 147 million hm2 of land with Fenlong cultivation could increase loosing soil to 315.491 billion m3, in＊ creasing by 159.26% for 120 million hm2 of arable land with the average tilled layer of 16.5 cm, which has loosing soil of only 198.1 billion m3, that is, the space of the land increases 1.6 times. Second, every hectare of plowland could store up to 450 m3/hm2 of natural rainfall, and the unused 60 m3 of saline-alkali soil and grasslands could store water of 102 billion m3, showing an increase of over 88.89% for the current plowland storage of 54 billion m3 at now, that is, double the natural rainfall storage capacity. Third, the two multiple increase of natural resources application can bring trillions of resource activation, environmental cleaning, food security, citizens, health, economic, ecological and social benefits, and makes the Chinese nation move forward in green development. Its application in ＂big scientific research＂ and ＂One Belt And One Road＂ will contribute Chinese strength to the world.

Steric Effects in the Cl＋CHD3（v1=1） Reaction

A recent study has revealed a full 3-dimentional reactive scattering picture of the reaction CI＋CHD3（v1=1） as the C1 atoms attack CHD3 from various directions respective to the C-H stretching bond. The reported polarization-dependent differential cross sections provide the most detailed characterization of the influences of reagent alignments on reactivity. To convey the stereo-specific information more accessible to general chemists, we show here, by proper symmetry considerations, how to retrieve from the measurements the relative integral and differential cross sections of two most common collision geometries： the end-on versus side-on attacks. The results, albeit coarse-grained, provide an appealing picture that not only reinforces our intuition about chemical reactivity, but also sheds more light on the conventional （unpolarized） attributes.

Application of Intensive Closed-type Float System in Tobacco Nursery

Due to the continuous low temperature during the early-nursery period in most tobacco-growing areas in Guizhou Province, the tobacco seed germinate slow-ly, the nursery period is prolonged, the quality of tobacco seedlings are not that good, the transplanting is delayed, etc. A comparative test of intensive closed-type floating-seedling system and conventional floating-seedling system was carried out in this study. The results showed that the intensive closed-type floating system could shorten significantly the nursery period; enhance the growth of tobacco seedlings;improve significantly the appearance of agronomic traits, such as number of leaves, stem height, stem diameter, fresh weight of leaves, etc; increase slightly the chloro-phyl content in seedlings. However, the root fresh weight and root vigor of seedlings nursed with the intensive closed-type float system were lower than that of seedlings nursed with the conventional float system. The intensive closed-type float system had a certain application potential in tobacco production.

Nanosize Catalysis Nanoscale Moleculars Structures

The catalytic system is investigated in a computer chromatography. The sorbent represents the nanostructure composite with hardpolymer electrolyt. As the nanostructure polymeric system, it used dendrimer who are absorbed on a surface with formation of monolayer. In chromatography column watch dimensional effect. The size of a particle carries out a role of temperature. In the article, investigate solvatation and dimensional effect reaction self-assembling gas dimmers. Distance critical radius H＋ transfer define equation： rcr = 2rs. Reaction accompaniment transfer energy. Transfer energy realize on exchange-resonanse mechanism.

Size effect on cubic and prismatic compressive strength of cement paste

A series of compression tests were conducted on 150 groups of cement paste specimens with side lengths ranging from 40 mm to 200 mm. The specimens include cube specimens and prism specimens with height to width ratio of 2. The experiment results show that size effect exists in the cubic compressive strength and prismatic compressive strength of the cement paste, and larger specimens resist less in terms of strength than smaller ones. The cubic compressive strength and the prismatic compressive strength of the specimens with side length of 200 mm are respectively about 91% and 89% of the compressive strength of the specimens with the side length of 40 mm. Water to binder ratio has a significant influence on the size effect of the compressive strengths of the cement paste. With a decrease in the water to binder ratio, the size effect is significantly enhanced. When the water to binder ratio is 0.2, the size effects of the cubic compressive strength and the prismatic compressive strength of the cement paste are 1.6 and 1.4 times stronger than those of a water to binder ratio of 0.6. Furthermore, a series of formulas are proposed to calculate the size effect of the cubic compressive strength and the prismatic compressive strength of cement paste, and the results of the size effect predicted by the formulas are in good agreement with the experiment results.

A Lifting Line Theory for a Three-dimensional Hydrofoil

Prandtl’s lifting line theory was generalized to the lifting problem of a three-dimensional hydrofoil in the presence of a free surface. Similar to the classical lifting theory, the singularity distribution method was utilized to solve two-dimensional lifting problems for the hydrofoil beneath the free surface at the air-water interface, and a lifting line theory was developed to correct three-dimensional effects of the hydrofoil with a large aspect ratio. Differing from the classical lifting theory, the main focus was on finding the three-dimensional Green function of the free surface induced by the steady motion of a system of horseshoe vortices under the free surface. Finally, numerical examples were given to show the relationship between the lift coefficient and submergence Froude numbers for 2-D and 3-D hydrofoils. If the submergence Froude number is small free surface effect will be significant registered as the increase of lift coefficient. The validity of these approaches was examined in comparison with the results calculated by other methods.

Science Letters:New solutions of shear waves in piezoelectric cubic crystals

Acoustic wave propagation in piezoelectric crystals of classes 43m and 23 is studied. The crystals Tl3VS4 and Tl3TaSe4 （43m） of the Chalcogenide family and the crystal Bi12TiO20 （23） possess strong piezoelectric effect. Because the surface Bleustein-Gulyaev waves cannot exist in piezoelectric cubic crystals, it was concluded that new solutions for shear-horizontal surface acoustic waves （SH-SAWs） are found in the monocrystals using different electrical boundary conditions such as electrically ＂short＂ and ＂open＂ free-surfaces for the unique [ 101 ] direction of wave propagation. For the crystal Tl3TaSe4 with coefficient of electromechanical coupling （CEMC） Ke^2=e^2/（C×g）-1/3, the phase velocity Vph for the new SH-SAWs can be calculated with the following formula： Vph=（Vα＋Vt）/2, where Vt is the speed of bulk SH-wave, Vt=Vt4（1＋Ke^2）^1/2, Vα=αKVt4, αK=2[Ke（1＋Ke^2）^1/2-Ke^2]^1/2, and Vt4=（C44/p）^1/2. It was found that the CEMC K2 evaluation for Tl3TaSe4 gave the value of K^2=2（Vf-Vm）/Vf-0.047 （-4.7%）, where Vf-848 m/s and Vm-828 m/s are the new-SAW velocities for the free and metallized surfaces, respectively. This high value of KZ（Tl3TaSe4） is significantly greater than K2（Tl3VS4）-3% and about five times that of K2（Bi12YiO20）.

Highly-efficient Stereo-cultivation Model in Kiwifruit Orchards Interplanting Konjak

The kiwifruit orchards with plants growing for over two years were chosen for interplanting of konjak, which takes advantages of complementation of the two plants in terms of habits, reducing water and soil erosions effectively, and decreasing water evaporation, and konjak diseases. Furthermore, the interplanting doubles planting benefits and constitutes a highly-efficient planting model.

An Efficient Approach to Narrow the Emission Band of Pyrene-Based Emitters

The construction of high color purity and high resolution organic light-emitting diodes(OLEDs)is facilitated by the development of highly-efficient organic luminescent materials with narrow-band emission.Herein,in order to address the problem of broad emission spectra of organic luminescent materials,an effective molecular design strategy is presented to reduce the full width at half maximum(FWHM)of emission by integrating the steric hindrance effect in the pyrene system.As the bulky group was introduced into the 2-position,compounds 5 not only show a relative high quantum yield(>0.31)in the solid state,but also can suppress the molecular rotation of triphenylamine(TPA)at the 3-position to narrow the FWHM in the solid state compared to that in solution.Compound 5c containing biphenyl units exhibits a maximum emission peak at 484 nm with a quantum yield of 0.38 and FWHM value of 49 nm in the solid state.

运用Flash制作课件动画——圆锥曲线

案例名称动画制作:平面切割圆锥产生圆锥曲线动画。技能目标能较熟练地运用flash中的绘图工具绘制动画中的各个素材(重点掌握渐变填充的方法);能较熟练地制作位移动画;能较好地运用图层,设置多个图层,以实现切割效果。

Theoretical insight into the stereometric effect of bisPC71BM on polymer cell performance

It has been experimentally demonstrated that the stereometric packings of two new bisPC_(71) BM isomers have an important impact on the power conversion efficiency of organic solar cells. Here, a theoretical investigation is made to reveal the mechanism behind from detailed photophysical processes in performed cells. The results show that the crystal packings of isomers affect the electron mobilities dominantly from the electronic coupling for electron transfer, and the trends of calculated mobilities are consistent with experimental measurements although the magnitudes are obviously larger. For the performed cells from two isomers with poly(3-hexylthiophene) as a donor, it is found that the exciton dissociation yields are also different, manifesting that stereometric packings essentially control the cell efficiency via both electron mobilities and exciton dissociation. Furthermore,the reasons for low cell efficiencies are analyzed, and possible improvements are suggested.

Recent progress in quantifying substituent effects

This paper summarizes significant progress in quantifying organic substituent effects in the last 20 years. The main content is as follows： （1） The principle of electronegativity equalization has gained wide acceptance, and has been used to calculate the intramolecular charge distribution and inductive effect of groups. A valence electrons equalization method was proposed to compute the molecular electronegativity on the basis of geometric mean method, harmonic mean method, and weighted mean method. This new calculation method further extended the application of the principle of electronegativity equalization. （2） A scale method was established for experimentally determining the electrophilic and nucleophilic ability of reagents, in which benzhydryliumions and quinone methides were taken as the reference compounds, and the research field was extended to the gas phase conditions, organometallic reaction and radicals system. Moreover, the nucleophilicity parameters N and electro- philicity parameters E for a series of reagents were obtained. The definition and quantitative expression of electrophilicity in- dex co and nucleophilicity index co were proposed theoretically, and the correlation between the parameters from experimental determination and the indexes from theoretical calculation was also investigated. （3） The polarizability effect parameter was initially calculated by empirical method and further developed by quantum chemistry method. Recently, the polarizability ef- fect index of alkyl （PEI） and groups （PEIx） were proposed by statistical method, and got wide applications in explaining and estimating gas-phase acidity and basicity, ionization energy, enthalpy of formation, bond energy, reaction rate, water solubility and chromatographic retention for organic compounds. （4） The excited-state substituent constant Crcc obtained directly from the UV absorption energy data of substituted benzenes, is different from the polar constants in molecular ground state and the radical spin-delocalization effects constants in molecular radical state. The proposed constant Crcc correlated well with the UV absorption energy of many kinds of organic compounds, such as 1,4-disubstituted benzenes, substituted stilbenes, and di- substituted N-benzylidenebenzenamine. （5） The establishment of the steric shielding effect distinguished the three traditional steric effects. The stereoselectivity index Ci was proposed to quantify the stereoselectivity of the addition reaction of carbonyl with nucleophilic reagent. The shielding parameter Rs was defined to quantitatively express the specific surface of the reac- tion center screened by a group. Further, the Topological Steric Effect Index （TSEI） of a group was proposed on the basis of the relative specific volume of reaction center screened by the atoms of substituents. These parameters can be applied in esti- mating the intramolecular dihedral angles, stereoselectivity of reaction, enthalpies of formation of alkenes and alkylbenzene, acidity of substitutedimidazolium ionic liquid, and the reaction rate of alkane and hydroxyl radical. In addition, some sugges- tions and prospects for further studies on quantifying the organic substituent effects were presented in this paper.

A single stage EEHG at SXFEL for narrow-bandwidth soft X-ray generation

The echo-enabled harmonic generation （EEHG） scheme holds promising prospects for efficiently generat- ing intense coherent radiation at very high harmonics of the initial seed laser. In this paper, we study the feasibility of operating the Shanghai X-ray free-electron laser test facility with a single stage EEHG setup. With a combina- tion of existing numerical codes, start-to-end simulations considering various three-dimensional effects have been carried out to show the possible performance of the EEHG FEL. Simulation results demonstrate that a single stage EEHG can generate high power soft X-ray radiation pulses with narrow bandwidth directly from UV seed lasers. With the help of the harmonic lasing technique or upgraded linac, we also show the possibility of generating coherent soft X-ray radiation in the ＂water window＂ with a single stage EEHG.

Stereomeric effects of bisPC_(71)BM on polymer solar cell performance

Two stereomers of bisadduct analogues of [6, 6]-phenyl-C71-butyric acid methyl ester （bisPC71BM） were synthesized and their geometrical structures with cis- or trans-configuration were identified by X-ray crystallogra- phy. Although both of the bisPC71BM have similar spec- trometric and electrochemical properties, the spatial orientation of the two addition groups on C7o has impact on crystal packing and molecular assembly of bisPC71BM isomers and, in turn, photovoltaic performance in polymer solar cell based on poly（3-hexylthiophene） （P3HT） （with power conversion efficiency of 1.72 % and 1.84 % for the solar cells involving cis- and trans-bisPC71BM, respec- tively）. Although the power conversion efficiency remains to be improved, this work exemplifies that the photovoltaic properties of fullerene-based electron acceptors areinfluenced by aggregation of the stereomeric molecules and thus extends the guidelines for rational design of efficient fullerene acceptor.

Control of organic–inorganic halide perovskites in solid-state solar cells: a perspective

Since the year of 2009 when the first appli- cation of organohalide lead perovskite as the light har- vester in solar cells was reported, tremendous attention has been devoted to these new types of perovskite-based solid-state solar cells and remarkable power conversion efficiency of over 20 % has been achieved to date. In this review, we first introduce the properties of organic- inorganic halide perovskites and then focus on the notable achievements made on the perovskite layer to improve the power conversion efficiency of solid-state perovskite solar cells, which is featured by process engineering of the state-of-the-art lead methylammoni- um triiodide perovskite and material control of lead triiodide perovskites and other newly emerged per- ovskites. In the end, we wish to provide an outlook of the future development in solid-state perovskite solar cells. Provided that the instability and toxicity of solid- state perovskite solar cells can be solved, we will wit- ness a new era for cost-effective and efficient solar cells.

BOSE COMPANION 20

咨询电话：400—880—2266 网址：www．bose．cn 近期BOSe在中国推出了全新的2．0电脑扬声器——Companion 20多媒体扬声器系统。此系统配备全新的强劲驱动单元和音频导孔设计，能够在全面广阔的音频范围内重现出效果逼真的音乐。

Size effect for achieving high mechanical performance body-centered cubic metals and alloys

Submicron and nanostructured body-centered cubic(BCC) metals exhibit unusual mechanical performance compared to their bulk coarse-grained counterparts, including high yield strength and outstanding ductility. These properties are important for their applications in micro-, nano-and even atomic-scale devices as well as for their usages as components for enhancing the performances of structural materials. One aspect of the unusual mechanical properties of small-sized BCC metals is closely related to their dimensional confinement. Decreasing the dimensions of single crystalline metals or the grain sizes of polycrystalline metals contributes significantly to the strengthening of the small-sized BCC metals.In the last decade, significant progress has been achieved in understanding the plasticity and deformation behaviors of small-sized BCC metals. This paper aims to provide a comprehensive review on the current understanding of size effects on the plasticity and deformation mechanisms of small-sized BCC metals. The techniques used for in situ characterization of the deformation behavior and mechanical properties of small-sized samples are also presented.

Theoretical studies on selectivities in the Staudinger reaction of vicinal diimines and ketenes

The selectivities, including peri-, regio-, and diastereoselectivities, in the Staudinger reaction involving vicinal diimines and ketenes were investigated theoretically via the density functional theory （DFT） calculation. The results indicate that vicinal diimines prefer stepwise [2＋2] cycloaddition rather than [2＋4] cycloaddition to generate cis-4-imino-β-lactams. The diimines attack the less sterically hindered exo-side of ketenes to generate zwitterionic intermediates, which directly undergo a conrota- tory ring closure to produce cis-4-imino-β-lactams whatever diimines with less or more bulky N-substituents. For unsymmetric vicinal ketoaldehyde-derived diimines, their ketimines attack the exo-side of ketenes and undergo a conrotatory ring closure to produce cis-4-aldimino-β-lactams due to less steric effect. The current theoretical studies provide very important information for in-depth understanding of the selective formation of mono-cis-β-lactams from vicinal diimines and ketenes.

Isotopic Effects on Stereodynamics of the C^+ + H_2→CH^+ + H Reaction

The effects of isotope substitution on stereodynamic properties for the reactions C^+ + H_2/HD/HT →CH^+ + H/D/T have been studied applying a quasi classical trajectory method occurring on the new ground state CH_2^+ potential energy surface [J. Chem. Phys. 142(2015) 124302]. In the center of mass coordinates applying the quasi classical trajectory method to investigate the orientation and the alignment of the product molecule. Differential cross section and three angle distribution functions P(θ_r), P(ф_r), P(θ_r, ф_r) on the potential energy surface that fixed the collision energy with a value is 40 kcal/mol have been studied. The isotope effect becomes more and more important with the reagent molecules H_2 changing into HD and HT. P(θ_r, ф_r) as the joint probability density function of both polar angles θ_r and ф_r, which can illustrate more detailed dynamics information. The isotope effect is obvious influence on the properties of stereodynamics in the reactions of C^+ + H_2/HD/HT → CH^+ + H/D/T.