顶岗实习管理机制提高就业率的研究与实践——以辽阳职业技术学院为例

通过对辽阳职业技术学院生物制药专业2010级、2011级学生顶岗实习情况的调查分析,构建"五化三落实"顶岗实习管理机制,提出顶岗实习是培养高技能人才的重要环节,是充分就业的有效途径.     

Magnetic and flotation studies of banded hematite quartzite (BHQ) ore for the production of pellet grade concentrate

To identify and establish beneficiation techniques for banded hematite quartzite (BHQ) iron ore, a comprehensive research on BHQ ore treatment was carried out. The BHQ ore was assayed as 38.9wt% Fe, 42.5wt% SiO₂, and 1.0wt% Al₂O₃. In this ore, hematite and quartz are present as the major mineral phases where goethite, martite, and magnetite are present in small amounts. The liberation of hematite particles can be enhanced to about 82% by reducing the particle size to below 63 μm. The rejection of silica particles can be obtained by magnetic and flotation separation techniques. Overall, the BHQ ore can be enriched to 65.3wt% Fe at 61.9% iron recovery. A flowsheet has been suggested for the commercial exploitation of the BHQ ore.     

The structural basis for autonomous dimerization of the pre-T-cell antigen receptor

The pre-T-cell antigen receptor (pre-TCR), expressed by immature thymocytes, has a pivotal role in early T-cell development, including TCR β-selection, survival and proliferation of CD4(-)CD8(-) double-negative thymocytes, and subsequent αβ T-cell lineage differentiation. Whereas αβTCR ligation by the peptide-loaded major histocompatibility complex initiates T-cell signalling, pre-TCR-induced signalling occurs by means of a ligand-independent dimerization event. The pre-TCR comprises an invariant α-chain (pre-Tα) that pairs with any TCR β-chain (TCRβ) following successful TCR β-gene rearrangement. Here we provide the basis of pre-Tα-TCRβ assembly and pre-TCR dimerization. The pre-Tα chain comprised a single immunoglobulin-like domain that is structurally distinct from the constant (C) domain of the TCR α-chain; nevertheless, the mode of association between pre-Tα and TCRβ mirrored that mediated by the Cα-Cβ domains of the αβTCR. The pre-TCR had a propensity to dimerize in solution, and the molecular envelope of the pre-TCR dimer correlated well with the observed head-to-tail pre-TCR dimer. This mode of pre-TCR dimerization enabled the pre-Tα domain to interact with the variable (V) β domain through residues that are highly conserved across the Vβ and joining (J) β gene families, thus mimicking the interactions at the core of the αβTCR's Vα-Vβ interface. Disruption of this pre-Tα-Vβ dimer interface abrogated pre-TCR dimerization in solution and impaired pre-TCR expression on the cell surface. Accordingly, we provide a mechanism of pre-TCR self-association that allows the pre-Tα chain to simultaneously 'sample' the correct folding of both the V and C domains of any TCR β-chain, regardless of its ultimate specificity, which represents a critical checkpoint in T-cell development. This unusual dual-chaperone-like sensing function of pre-Tα represents a unique mechanism in nature whereby developmental quality control regulates the expression and signalling of an integral membrane receptor complex.     

Hydrometallurgical application for treating a Nigerian chalcopyrite ore in chloride medium: Part I. Dissolution kinetics assessment

The dissolution kinetics of a Nigerian chalcopyrite ore in hydrochloric acid was studied in this article. Acid concentration, reaction temperature, and ore particle size were chosen as experimental parameters. The chemical and morphological studies of the ore before and after leaching at optimal conditions were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It is revealed that increasing the acid concentration and system temperature and decreasing the ore particle size greatly enhances the dissolution rate. The dissolution kinetics was found to follow the shrinking core model for the diffusion control mechanism where the activation energy (E_a) of 32.92 kJ·mol?1 was obtained for the process and supported by morphological changes at a higher dissolution of 91.33%.     

基于改进S变换的配电网故障定位方法

该文提出了一种基于改进S变换提取行波特征频率的配电网故障定位方法。配电线路故障产生的暂态行波在波阻抗不连续点之间来回反射,从而在不同的振荡路径上形成不同的特征频率分量,根据故障路径特征频率分量的大小可以计算出故障距离。S变换是一种性能优越的时频分析方法,该文将其应用到行波特征频率的提取中,仿真结果验证了该方法相此基于Morlet连续小波变换方法的优越性。     

矿区连续运行参考站选址分析

对连续运行参考站的选址问题进行了探讨,结合鲁西矿区连续运行卫星定位服务综合系统参考站的实际选址工作,论述了其选址的原则.采用TEQC软件时拟建参考站A和B的观测数据进行全面的质量分析,同时把分析的结果和已建成的C参考站的数据进行对比,从而确定出更适合作为连续运行参考站的站点.经对A参考站试运行期间的数据验证,所选参考站点完全满足参考站建设技术规范和矿区应用的需求.     

Short Report： Cyclic patterns of incidence rate for skin malignant melanoma： association with heliogeophysical activity

Background： Our previous studies revealed cyclicity in the incidence rate of skin malignant melanoma （SMM; ICD9, Dx： 172） in the Czech Republic （period T=7.50～7.63 years）, UK （T= 11.00 years） and Bulgaria （T= 12.20 years）. Incidences com- pared with the sunspot index Rz （lag-period dT=＋2, ＋4, ＋6, ＋ 10 or ＋ 12 years） have indicated that maximal rates are most likely to appear on descending slopes of the ;ll-year solar cycle, i.e., out of phase. We summarized and explored more deeply these cyclic variations and discussed their possible associations with heliogeophysical activity （HGA） components exhibiting similar cyclicity. Methods： Annual incidences of SMM from 5 countries （Czech Republic, UK, Bulgaria, USA and Canada） over various time spans during the years 1964-1992 were analyzed and their correlations with cyclic Rz （sunspot number） and aa （planetary geomagnetic activity） indices were summarized. Periodogram regression analysis with trigonometric approximation and phase-correlation analysis were applied. Results： Previous findings on SMM for the Czech Republic, UK and Bulgaria have been validated, and cyclic patterns have been revealed for USA （T=8.63 years, P〈0.05） and Canada （Ontario, T=9.91 years, P〈0.10）. Also, various ＇hypercycles＇ were established （T=45.5, 42.0, 48.25, 34.5 and 26.5 years, respectively） describing long-term cyclic incidence patterns. The association of SMM for USA and Canada with Rz （dT=＋6 and ＋7 years, respectively） and aa （dT=-10 and ＋9 years, respectively） was described. Possible interactions of cyclic non-photic influences （UV irradiation, Schumann resonance signal, low-frequency geomagnetic fluctuations） with brain waves absorbance, neuronal calcium dynamics, neuro-endocrine axis modulation, melatonin/serotonin disbalance and skin neuro-immunity impairment as likely causal pathways in melanoma appearance, were also discussed. Conclusion： The above findings on cyclicity and temporal assoc     

Lateral presynaptic inhibition mediates gain control in an olfactory circuit

Olfactory signals are transduced by a large family of odorant receptor proteins, each of which corresponds to a unique glomerulus in the first olfactory relay of the brain. Crosstalk between glomeruli has been proposed to be important in olfactory processing, but it is not clear how these interactions shape the odour responses of second-order neurons. In the Drosophila antennal lobe (a region analogous to the vertebrate olfactory bulb), we selectively removed most interglomerular input to genetically identified second-order olfactory neurons. Here we show that this broadens the odour tuning of these neurons, implying that interglomerular inhibition dominates over interglomerular excitation. The strength of this inhibitory signal scales with total feedforward input to the entire antennal lobe, and has similar tuning in different glomeruli. A substantial portion of this interglomerular inhibition acts at a presynaptic locus, and our results imply that this is mediated by both ionotropic and metabotropic receptors on the same nerve terminal.