控制“温室效应”

本文简要叙述了太阳辐射能途经大气层时,由于大气中二氧化碳和水蒸气吸收其长波辐射能并将其一部分反射到地球表面,而造成了“温室效应”。文中论述了生物圈中的碳循环,由于人类活动的加剧,使这种碳循环遭到破坏,大气中二氧化碳含量剧增,导致“温室效应”加剧,气候变暖。文中列举了人口激增的情况,由此造成矿物燃料消耗增大以及森林面积的锐减,因而导致“温室效应”的加剧。由此给人类带来巨大危害。为此,文中最后指出“温室效应”必须控制,并呼吁我们必须爱护人类唯一拥有的地球。     

Switching "on" and "off" the expression of chirality in peptide rotaxanes

The hydrogen-bond-directed synthesis, X-ray crystal structures, and optical properties of the first chiral peptide rotaxanes are reported. Collectively these systems provide the first examples of single molecular species where the expression of chirality in the form of a circular dichroism (CD) response can selectively be switched "on" or "off", and its magnitude altered, through controlling the interactions between mechanically interlocked submolecular components. The switching is achievable both thermally and through changes in the nature of the environment. Peptido[2]rotaxanes consisting of an intrinsically achiral benzylic amide macrocycle locked onto various chiral dipeptide (Gly-L-Ala, Gly-L-Leu, Gly-L-Met, Gly-L-Phe, and Gly-L-Pro) threads exhibit strong (10-20k deg cm(2) dmol(-1)) negative induced CD (theta;) values in nonpolar solvents (e.g. CHCl(3)), where the intramolecular hydrogen bonding between thread and macrocycle is maximized. In polar solvents (e.g., MeOH), where the intercomponent hydrogen bonding is weakened, or switched off completely, the elliptical polarization falls close to zero in some cases and can even be switched to large positive values in others. Importantly, the mechanism of generating the switchable CD response in the chiral peptide rotaxanes is also determined: a combination of semiempirical calculations and geometrical modeling using the continuous chirality measure (CCM) shows that the chirality is transmitted from the amino acid asymmetric center on the thread via the macrocycle to the C-terminal stopper of the rotaxane. This understanding could have important implications for other areas where chiral transmission from one chemical entity to another underpins a physical or chemical response, such as the seeding of supertwisted nematic liquid crystalline phases or asymmetric synthesis.     

Excited-state behavior of N-phenyl-substituted trans-3-aminostilbenes: where the "m-amino effect" meets the "amino-conjugation effect"

The electronic spectroscopy and photochemistry of the trans isomers of 3-(N-phenylamino)stilbene (m1c), 3-(N-methyl-N-phenylamino)stilbene (m1d), 3-(N,N-diphenylamino)stilbene (m1e), and 3-(N-(2,6-dimethylphenyl)amino)stilbene (m1f) and their double-bond constrained analogues m2a-m2c and m2e are reported. When compared with trans-3-aminostilbene (m1a), m1c-m1e display a red shift of the S0 --> S1 absorption and fluorescence spectra, lower oscillator strength and fluorescence rate constants, and more efficient S1 --> T1 intersystem crossing. Consequently, the N-phenyl derivatives m1c-m1e have lower fluorescence quantum yields and higher photoisomerization quantum yields. The corresponding N-phenyl substituent effect in m2a-m2e is similar in cyclohexane but smaller in acetonitrile. This is attributed to the weaker intramolecular charge transfer character for the S1 state of m2 so that the rates for intersystem crossing are less sensitive to solvent polarity. It is also concluded that N-phenyl substitutions do not change the triplet mechanism of photoisomerization for m1 in both nonpolar and polar solvents. Therefore, the "m-amino conjugation effect" reinforces the "m-amino effect" on fluorescence by further reducing its rate constants and highlights the N-phenyl-enhanced intersystem crossing from the "amino-conjugation effect" by making S1 --> T1 the predominant nonradiative decay pathway.     

"Adiabatic-hindered-rotor" treatment of the parahydrogen-water complex

Inspired by a recent successful adiabatic-hindered-rotor treatment for parahydrogen pH(2) in CO(2)-H(2) complexes [H. Li, P.-N. Roy, and R. J. Le Roy, J. Chem. Phys. 133, 104305 (2010); H. Li, R. J. Le Roy, P.-N. Roy, and A. R. W. McKellar, Phys. Rev. Lett. 105, 133401 (2010)], we apply the same approximation to the more challenging H(2)O-H(2) system. This approximation reduces the dimension of the H(2)O-H(2) potential from 5D to 3D and greatly enhances the computational efficiency. The global minimum of the original 5D potential is missing from the adiabatic 3D potential for reasons based on solution of the hindered-rotor Schro?dinger equation of the pH(2). Energies and wave functions of the discrete rovibrational levels of H(2)O-pH(2) complexes obtained from the adiabatic 3D potential are in good agreement with the results from calculations with the full 5D potential. This comparison validates our approximation, although it is a relatively cruder treatment for pH(2)-H(2)O than it is for pH(2)-CO(2). This adiabatic approximation makes large-scale simulations of H(2)O-pH(2) systems possible via a pairwise additive interaction model in which pH(2) is treated as a point-like particle. The poor performance of the diabatically spherical treatment of pH(2) rotation excludes the possibility of approximating pH(2) as a simple sphere in its interaction with H(2)O.     

Actin-binding toxin "tail" wags the dog

Actin-binding marine macrolides exhibit significant structural and functional diversity. In this issue, Perrins et al. demonstrate that a long stereochemically conserved aliphatic side chain, known as the "tail", found in many of these compounds is the functional determinant of cytotoxicity (Perrins et al., 2008).     

关于为拔尖人才培养开设的"学科前沿"类课程的探讨

With the implementation of the basic discipline of "Top Talent Training Program" (the "East Ever Project"), more and more new reforms and attempts are being made in various universities. In the process of innovation and exploration, a new curriculum is being implemented, that is, the "the frontier aspects of disciplines" course. Through investigation and research, we found that many colleges and universities in China are carrying out or trying to carry out such courses, and the students who participated have different benefits. This paper mainly discusses the current situation of the development of the frontier courses of many universities in China, and gives suggestions based on the two courses of Tang Aoqing Honors Program in Science of chemistry in Jilin University. This paper provides reference for other colleges and universities to open such courses.     

《有机化学》教材及其《自学指导书》的简介

一、《有机化学》教材简介中央卫星电视中学教师进修化学专业专科用的《有机化学》教材即将出版,这本书是根据1984年原教育部组织制订的中学教师进修高等师范专科化学专业的有机化学教学大纲编写的,全书共19章,最后附习题解答。在编写过程中始终坚持高师专科的标准,即通过本教材的学习能够掌握高师专科有机化学的基本理论、基础知识;了解与本门学科有关的科学成就和新发展;能够提高分析和解决中学教学实际问题的能力;为胜任中学化学教学打下比较坚实的基础。这本教材的主要特点是:1.联系中学教学实际在编写过程中注意到在职进修教师的特点。     

Resonance CARS study of the structure of "green" and "red" chromophores within the red fluorescent protein DsRed

Vibrational spectra of red fluorescent protein DsRed have been studied for the first time by polarization-sensitive multiplex coherent anti-Stokes Raman scattering at two excitation wavelengths, 545 and 583 nm, in resonance with the absorption bands of the immature "green" and mature "red" protein chromophores. Overall vibrational patterns of both DsRed chromophores were found to be similar to each other and to differ from that of S65T-GFP at pH8. The combined analysis of our CARS data and published structural information suggest that both "green" and "red" DsRed species possess an extended chromophore structure. Consequently, our data suggest that pi-bonding system extension during isomerization around the cis peptide bond between Phe 65 and Gln 66 is a necessary but not sufficient step in DsRed chromophore maturation.     

On the nature of so-called "Khimdu"

The reagent called “Khimdu” has been investigated and evidence found to show that it is not a pure compound but a mixture of several reaction products.     

固态"绝对"不对称合成

光学活性生物分子的形成是世界进化历史中一个重要过程。"绝对"不对称合成, 即在没有任何外界手性诱导试剂作用下或在圆偏振光影响下的封闭体系中的不对称合成, 为前生物时期天然手性的成因提供了解释。本文将综述通过非手性分子形成的手性晶体的固相反应进行的"绝对"不对称合成。     

Possible mediators of the "living" radical polymerization

The stable radicals derived from different compounds were detected in process of styrene autopolymerization. The nitroxide radicals are produced from nitrosocompound, hindered hydroxylamine, nitrophenols and nitroanisoles. The phenoxyl radicals are formed from quinine methides, and naphtoxyl radicals are generated from 2-nitro-1-naphtol. The radicals are identified, the kinetics of their formation and follow-up evolution are studied. These radicals can participate in process of living radical polymerization as the mediators and can effect significantly on kinetics of polymerization and structure of the resulting polymer.     

An investigation into the human serum "interactome"

The protein content of human serum is composed of a millieu of proteins from almost every type of cell and tissue within the body. The serum proteome has been shown to contain information that directly reflects pathophysiological states and represents an invaluable source of diagnostic information for a variety of different diseases. Unfortunately, the dynamic range of protein abundance, ranging from > mg/mL level to < pg/mL level, renders complete characterization of this proteome nearly impossible with current analytical methods. To study low-abundance proteins, which have potential value for clinical diagnosis, the high-abundant species, such as immunoglobulins and albumin, are generally eliminated as the first step in many analytical protocols. This step, however, is hypothesized to concomitantly remove proteins/peptides associated with the high-abundant proteins targeted for depletion. In this study, immunoprecipitation was combined with microcapillary reversed-phase liquid chromatography (microRPLC) coupled on-line with tandem mass spectrometry (MS/MS) to investigate the low-molecular-weight proteins/peptides that associate with the most abundant species in serum. By this targeted isolation of select highly abundant serum proteins, the associated proteins/peptides can be enriched and effectively identified by microRPLC-MS/MS. Among the 210 proteins identified, 73% and 67% were not found in previous studies of the low-molecular-weight or whole-serum proteome, respectively.     

"Going KiNativ": probing the Native Kinome

In this issue, Patricelli et?al. (2011) describe an in?situ chemoproteomics approach (KiNativ?) for profiling the?kinome and kinome response to specific kinase inhibitors that enables characterization of inhibitor interactions with endogenously expressed kinases in native conditions.     

“能源化学”本科专业建设建议

"Energy chemistry" was approved as one of the chemistry majors for undergraduate by the Ministry of Education in 2015. Based on the ideas and ways of emerging engineering education, this paper hereby proposed some of constructive suggestions on the training objectives, graduation requirements, curriculum system, teaching contents, teaching staff and conditions for development of "energy chemistry" major.