Nickel accumulation and its effects on the survival rate of Spodoptera litura Fabricius under continuous nickel stress

The artificial diets mixed with various concentrations of nickel were offered to the larvae of the phytophagous insect Spodoptera litura Fabricius for 3 generations. Nickel accumulations in the 6th instar larvae, pupae and newly emerged adults of the corresponding generations of S. litura were investigated by Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES), and the effects of nickel accumulations on the survival rate of S. litura were also evaluated by individual rearing. The results showed that nickel accumulated in the 6th instar larvae, pupae and adults of S. litura, and the accu- mulated nickel in all the tested developmental stages within a generation increased with the increase of the nickel doses in the treated diets and showed significant dose-dependent relationship with the nickel doses in the artificial diets. The results also indicated that the nickel accumulations in the 6th instar larvae, pupae, and newly emerged adults from the 3rd generation were higher than those from the 2nd generation, which were also higher than those from the 1st generation. Nickel concentrations in pupae and adults were significantly lower than those in larvae, which indicated that the excessive nickel might be excreted during metamorphosis. Furthermore, larval survival rate, pupation rate and eclosion rate of S. litura in the tested three generations all decreased with the increase of the nickel doses in the treated diets.     

ASYMPTOTIC STABILITY OF SOLUTION TO THE INITIAL-BOUNDARY VALUE PROBLEM FOR SCALAR VISCOUS CONSERVATION LAWS CORRESPONDING TO RAREFACTION WAVES

1.IntroductionWeconsidertheinitial-boundaryvalueproblem(IBVP)forscalarviscousconservationlaw(ut f(u).=uxx,xE(0, co)=R ,t>0,o,(n \--9,ifI~9,f~M(IBVP){u(0't)=u~(t)-1~i---t:7),[u(x,0)=u000={=:0)f:LO .,wheref"(u)>0foralluunderconsideration,andu--u (1.1),andu~(t)~u~EL'(R ),U'(t)EL'(R ).(1.2)Undercondition(1.l)or(l.l)',thecorrespondingRiemannproblem{;;ot:<:>;i,>=x{,:3'f:,:(13)yieldstherarefaCtionwavesolution(u~)x5f'(u~)t,r"(X,t)=17j,)~1(…     

DFT study on nonlinear optical properties of lithium-doped corannulene

The effects of lithium doping on the nonlinear optical properties of new electrodes (lithium-doped corannulene) were investigated in detail. Nine dynamically stable geometries of Lin-C20H10 (n=1, 2) are predicted by B3LYP/6-31G(d,p). Among these nine structures, the largest first static hyperpolarizability (β0) is computed to be 15314 au, which is dramatically larger than the β0 value of 74 au for C20H10, indicating that Li doping plays an important role in elevating the first hyperpolarizability of corannulene.     

A multiphoton ionization study of acetone using time-of-flight mass spectrometry

The 3p Rydberg states of acetone and photodissociation of the acetone cation were studied using time-of-flight (TOF) mass spectrometry. The 3p Rydberg state spectroscopy of acetone was investigated with linearly polarized two-photon resonance enhanced multiphoton ionization (REMPI) from 320 to 337 nm. Several new transition bands were observed in the spectra. In addition to the CH₃COCH₃ ⁺ ion, CH₃CO⁺ and CH₃ ⁺ fragments were observed. The laser power dependences suggest that the CH₃COCH₃ ⁺, CH₃CO⁺ and CH₃ ⁺ ions are produced in three-, four-, and four-photon processes, respectively. Production of CH₃CO⁺ and CH₃ ⁺involves excitation of the ground state acetone cation by an additional photon and subsequent decomposition of the excited acetone ion. The average translational energies of CH₃CO⁺ and CH₃ ⁺ from dissociation in CH₃COCH₃ ⁺(X) + hv → CH₃CO⁺ + CH₃ and CH₃COCH₃ ⁺(X) + hv → CH₃ ⁺ + CH₃CO, respectively, were derived from the ion TOF peak profiles.     

Subspecies in Przewalski’s gazelle Procapra przewalskii and its conservation implication

Przewalski’s gazelle Procapra przewalskii is an endangered species endemic to China. A question remains about subspecific variation in this species. Skulls of Przewalski’s gazelle collected from its current remnant ranges around the Qinghai Lake in combination with those collected prior to the 20th century were measured and analyzed using Hierarchical Cluster Analysis in order to clarify the question. Unexpectedly, P. p. diversicornis, extirpated from its historic range, has spread to the Qinghai Lake region where it has replaced nominotypical P. p. przewalskii and is now restricted to a few small isolated populations around the lake. We discuss the causes of this unexpected replacement. In this study, we discuss the possibility of a new form, possibly a new subspecies, in the Guide Basin, adjacent to Qinghai Lake; it is unclear whether the new form has long existed and was only discovered in recent years, or whether it evolved in recent times due to the geographical isolation and anthropogenic landscape features. The study sheds light on the processes of microevolution and subspeciation in Procapra przewalskii, and based on the findings, we propose measures for conservation strategies for Przewalski’s gazelle.     

Effects of dietary nickel on detoxification enzyme activities in the midgut of <Emphasis Type="Italic">Spodoptera litura</Emphasis> Fabricius larvae

Nickel accumulated in midugt of Spodoptera litura Fabricius could induce the expression of metallothionein, one of the most important detoxification proteins in organisms. In the present study, the effects of dietary nickel on the activities of detoxification enzymes, such as carboxylesterase （CarE） and giutathione S-transferase （GST） in the midgut of S. litura larvae have been studied to get an understanding of the detoxification mechanisms of S. litura larvae to excessive nickel. Results showed that CarE activities in the midgut of the 5th instar larvae decreased at lower levels of nickel （≤5 mg/kg）, while increased with increasing nickel doses at higher levels of nickel （≥10 mg/kg） exposure in successive 3 generations. CarE activities of the 6th instar larvae were also characterized as inhibited at low levels of nickel exposure, and improved at higher levels in the 1st generation. CarE activities of 6th instar larvae in the 2nd and 3rd generations were all lower than that in control. However, GST activities in the midgut of the 5th and 6th instar larvae all increased with increasing nickel doses （1 --20 mg/kg） in diets.     

Filamentous cyanobacteria fossils and their significance in the Permian-Triassic boundary section at Laolongdong, Chongqing

The microbial communities blooming immediately after the end-Permian mass extinction represent abnormally extreme environments, and vary in different areas. In this study, filamentous cyanobacterial biota was found in the strata after the extinction in the famous Permian-Triassic boundary section at Laolongdong, Chongqing, southwest China. In thin sections, the filamentous cyanobacterial fossils are below 1 mm in length, and generally taper to one end, with the widest diameter up to 0.08 mm. Some of them are curved, indicating that they are soft in life. Their walls are composed of cryptocrystalline to microcrystalline calcites. The filaments have round cross section, and are internally filled with micrites and fine sparry calcites, which indicate that the filaments are originally empty. They are randomly distributed in the rocks, but in some places, they tend to be distributed in radial pattern. The filamentous organisms are morphologically similar to Rivularia of Rivulariaceae, Cyanobacteria Phylum, but with calcified sheaths, and are tentatively regarded as an indeterminate new species in Rivularia： Rivularia sp. Cyanobacteria are photosynthetic autotrophic, and can survive in dysoxic condition. The blooming of this organism and the absence of other organisms may indicate that the environment was oxygendeficient and shallow, since this photosynthetic autotrophic organism needed to live within photic.     

Roles of flanking sequences in the binding between unimolecular parallel-stranded G-quadruplexes and ligands

G-quadruplexes attract more and more attention in recent years.Numerous small molecules which can induce or stabilize the formation of G-quadruplexes have been investigated on the purpose of anticancer drug development.As a motif existed in physiological condition,flanking sequences are an important part of G-quadruplexes but the study on the impact of flanking sequences on (G-quadruplex)-ligand binding is rarely reported.In this paper,the effects of flanking sequences on binding affinity between a series of unimolecular parallel-stranded G-quadruplex sequences derived from c-myc oncogene promoter (termed as c-myc G-quadruplexes) and their ligands are discussed in detail.The results showed that the flanking sequences on c-myc G-quadruplexes play key roles in (G-quadruplex)-ligand interaction.When a c-myc G-quadruplex is bound to its ligands,the flanking sequences might form a binding cavity above the terminal G-quartet,which could provide a suitable site for ligands to dock in.Moreover,the bases on flanking sequences could interact with ligand through π-π stacking,and finally form a sandwich-stacking mode (terminal G-quartet,ligand and bases on the flanking sequence).This mode could stabilize the (G-quadruplex)-ligand complex effectively and enhance the binding affinity dramatically.However,flanking sequences are also found to exhibit steric hindrance effect which could impede the (G-quadruplex)-ligand binding.     

Extinction pattern of reef ecosystems in latest Permian

Studies of two Permian-Triassic boundary (PTB) sections on top of a Changhsingian reef in Ziyun, Guizhou Province, southwestern China indicate that the end-Permian mass extinction of reef ecosystems occurred in two steps. The first step is the extinction of all stenotropic organisms such as calcisponges and fusulinids in the latest Permian (in the Clarkina yini conodont zone). The biota after the first extinction is simple, comprising eurytropic organisms including microgastropods, ostracods, and some small burrowing organisms, or only algal mats. At the beginning of the Early Triassic (i.e. the beginning of the Hindeodus parvus zone), the environments became anoxic, and the microgastropod dominated biota or algal mats disappeared, which constituted the second episode of the mass extinction. The biota after the second extinction comprises small spherical microproblematica, some kinds of specialized organisms tolerant of anoxic or oxygen-poor conditions. As the environments became oxygenated, the specialized biota was replaced by a microgastropod-dominated simple biota. When the environmental conditions improved further, the simple biota was replaced by a diverse biota with normal-sized ammonoids, bivalves, and gastropods, representing restoration of normal oceanic condi- tions. Comparison with PTB sections in Dolomites, Italy and Meishan, Zhejiang Province shows that non-reef ecosystems had a similar first episode of mass extinction in the latest Permian. In the case that oceanic anoxia happened, non-reef ecosystems had a second extinction episode similar to that of reef ecosystems.     

生物基衣康酸酯橡胶的设计开发与工业应用

利用可再生资源开发新一代生物基橡胶材料对于实现我国合成橡胶工业可持续发展具有重要意义。多年来,北京化工大学先进弹性体材料研究中心对生物基衣康酸酯橡胶进行了系统的分子设计、应用开发与工程放大研究。实验室阶段的研究主要包括生物基单体的选择、橡胶分子链的构建及聚合体系的优化、官能化技术开发、结构/胎面指标的灵活调控。在此基础上,与山东京博中聚新材料有限公司合作,历经2L小试—200L中试—千吨级的生产过程,解决了衣康酸酯橡胶在工业化进程中出现的实际问题,最终建立了千吨级聚合装置以及适配的絮凝干燥线,实现了衣康酸酯橡胶的稳定生产。与山东玲珑股份有限公司合作,基于该生物基橡胶材料的特点,研发了相适配的混炼配方及生产工艺,制备了首批双B级生物基子午线轮胎。生物基衣康酸酯橡胶的生产技术成果转化可以实现生物质资源的高附加值利用,促进我国橡胶产业的绿色可持续发展。