Chromosomal organization of simple repeated DNA sequences used for DNA fingerprinting

Stretches of short, simple DNA sequences are widespread in all eukaryote genomes studied so far. Simple sequences are thought to undergo frequent expansion and deletion due to intrinsic genomic mechanisms. Some of the simple sequences were used successfully to detect hypervariable loci in various genomes. Hybridization experiments using synthetic probes not only revealed the informative simple repeats suitable for DNA fingerprinting in a particular species, but also reflected the wide range of distribution of the simple sequences among eukaryotes. The organization of these simple repetitive sequences at the chromosomal loci was investigated using in situ hybridization with chemically synthesized, pure oligonucleotide probes. Both biotin- and digoxigenin-attached probes detected specific chromosomal sites that are enriched in the respective simple-repeat blocks. Depending on the organism and probe used, accumulation of simple DNA sequences at individual or multiple sites on the chromosomes of different vertebrates could be demonstrated. The simple repetitive DNA sequences are located in different chromosomal regions (e.g., heterochromatin on the sex chromosomes, nucleolus organizer regions, and R-band sites), which are constrained considerably during evolution.     

Estimation of Joule heating effect on temperature and pressure distribution in electrokinetic-driven microchannel flows

In this study we present simple analytical models that predict the temperature and pressure variations in electrokinetic-driven microchannel flow under the Joule heating effect. For temperature prediction, a simple model shows that the temperature is related to the Joule heating parameter, autothermal Joule heating parameter, external cooling parameter, Peclet number, and the channel length to channel hydraulic diameter ratio. The simple model overpredicted the thermally developed temperature compared with the full numerical simulation, but in good agreement with the experimental measurements. The factors that affect the external cooling parameters, such as the heat transfer coefficient, channel configuration, and channel material are also examined based on this simple model. Based on the mass conservation, a simple model is developed that predicts the pressure variations, including the temperature effect. An adverse pressure gradient is required to satisfy the mass conservation requirement. The temperature effect on the pressure gradient is via the temperature-dependent fluid viscosity and electroosmotic velocity.     

Cholesterol Binding to Simple Micelles in Aqueous Bile-Salt–Cholesterol Solutions

The true thermodynamic activity (A_T) of cholesterol (Ch) in aqueous solutions containing taurocholate (TC)–Ch was determined by employing a direct assay of a 1 × 2-cm silicone polymer film with 0.025 cm thickness. Using theA_Tdata, information on the nature of micellar species present in the TC–Ch system, and employing a binding-site model previously developed for tauroursodeoxycholate (TUDC)–Ch and taurochenodeoxycholate (TCDC)–Ch systems, it appeared that the Ch-binding affinity for simple bile-salt micelles corresponds precisely with the order of hydrophobicity, TUDC < TC < TCDC. Further, although simple TC micelles and simple TCDC micelles have similar binding capacities, the first Ch binding to a simple TC micelle may not significantly facilitate the second Ch binding, as occurs in simple TCDC micelles. For TUDC–Ch, TC–Ch, and TCDC–Ch systems, the concentration of bound simple micelles increased with increasingA_Tvalues, whereas the unbound simple micelle concentration decreased proportionally. These results provide insights into the possible influence of bile-salt species on Ch-binding to simple micelles in bile-salt–Ch solutions.     

Exploiting green analytical procedures for acidity and iron assays employing flow analysis with simple natural reagent extracts

Green analytical methods employing flow analysis with simple natural reagent extracts have been exploited. Various formats of flow based analysis systems including a single line FIA, a simple lab on chip with webcam camera detector, and a newly developed simple lab on chip system with reflective absorption detection and the simple extracts from some available local plants including butterfly pea flower, orchid flower, and beet root were investigated and shown to be useful as alternative self indicator reagents for acidity assay. Various tea drinks were explored to be used for chromogenic reagents in iron determination. The benefit of a flow based system, which allows standards and samples to go through the analysis process in exactly the same conditions, makes it possible to employ simple natural extracts with minimal or no pretreatment or purification. The combinations of non-synthetic natural reagents with minimal processed extracts and the low volume requirement flow based systems create some unique green chemical analyses.     

A rate law model for the explanation of complex pH oscillations in the thiourea-iodate-sulfite flow system

In a continuous flow stirred tank reactor (CSTR), the reaction of thiourea-iodate-sulfite (TuIS) exhibits a rich variety of complex oscillations in pH. The transitions from 1(n) type oscillations to 1(3), 1(2) type and simple oscillations were observed on decreasing the flow rate gradually in small steps at 30.2 °C and 20.5 °C, respectively. The transitions from 1(n) type oscillations to 1(0)1(4), 1(0)1(3) type and simple oscillations were observed as well on increasing the temperature in small steps at a given flow rate. Based on the analogous iodate-sulfite-thiosulfate system a simple empirical rate law model is suggested to give a sound agreement between the experimental and simulated results on the complex oscillatory behaviour. A possible explanation of the emergence of the simple empirical rate law model from the mechanism of the individual reactions of the TuIS system is also discussed.     

Measurement of column dead time in capillary gas chromatography

Two simple methods are given for calculation of accurate values of column dead time (tM) from the unadjusted retention times of liquid n-alkanes. Both are iterative methods that are based on the linearity of a plot of log k' against the carbon number of the alkanes. One can be done on an ordinary programmable calculator; the other uses a simple matrix-manipulation com- puter program. These methods also provide a simple way to measure Kovits indices.     

Molecules of jellium dimers

A simple tight-binding-like model of the electronic structure of simple metal clusters is presented which relies on the special stability of the first shell closures atN _el=2 andN _el=8. The wavefunctions, energy levels, and ground state deformations of the “ultimate jellium model”, which is based on a full Kohn-Sham treatment of the electrons, can be explained relying on a simple geometrical growth pattern complemented by an extremely simplified Hamiltonian matrix. The bulk and surface limits of the model also yield reasonable results.     

一种便携式有毒气体被动采样检测装置的研制

以甲醛作为目标物,提出了一种基于扩散原理的具有大面积表面暴露的快速被动采样器及快速测定装置。该采样器不要求任何辅助采样泵使用该采样器研发的快速测定装置适用于现场气体样品的采集与测定。     

反对数微分简易示波伏安法的研究

在获得微分简易地波伏安图的实验线路中,增加了反对数装置,提出了反对数微分简易示波伏安法。该方法被应用于铝合金中微量铜和分子筛中微量钴的测定,获得了满意结果。     

Comment on ‘Topological Analysis of the Eigenvalues of the Adjacency Matrices in Graph Theory: A Difficulty with the Concept of Internal Connectivity’

Net signs of edge-signed graphs obtained for different choices of degenerate eigenvectors of an adjacency matrix are shown to become equal with a simple weighting procedure. However, in a few cases, this simple procedure is found to yield orderings of the eigenvectors based on the weighted net signs which are different from the orderings based on the eigenvalues.     

Variationally optimized basis orbitals for biological molecules

Numerical atomic basis orbitals are variationally optimized for biological molecules such as proteins, polysaccharides, and deoxyribonucleic acid within a density functional theory. Based on a statistical treatment of results of a fully variational optimization of basis orbitals (full optimized basis orbitals) for 43 biological model molecules, simple sets of preoptimized basis orbitals classified under the local chemical environment (simple preoptimized basis orbitals) are constructed for hydrogen, carbon, nitrogen, oxygen, phosphorous, and sulfur atoms, each of which contains double valence plus polarization basis function. For a wide variety of molecules we show that the simple preoptimized orbitals provide well convergent energy and physical quantities comparable to those calculated by the full optimized orbitals, which demonstrates that the simple preoptimized orbitals possess substantial transferability for biological molecules.     

Iridium‐Catalyzed Carbonylative Synthesis of Chromenones from Simple Phenols and Internal Alkynes at Atmospheric Pressure

A novel procedure on the carbonylative synthesis of chromenones has been developed. With simple phenols and internal alkynes as the substrates, various chromenones were isolated in moderate to good yields with excellent regioselectivity and functional‐group tolerance by using iridium as the catalyst and copper as the promotor at atmospheric pressure. Notably, this is the first example on carbonylative annulation of simple phenols and alkynes.     

Fast vector-scalar-multiply-and-add subroutines for VAX computers

We describe a set of simple VAX assembly language, Fortran-callable subroutines for performing vectorscalar-multiply-and-add operations which can increase processing speed by more than 10%. The routines are simple enough that they may be translated readily for use on other machines.     

Population analysis of pair densities: A link between quantum chemical and classical picture of chemical structure

The pairon population analysis based on the geminal expansion of pair densities is introduced and applied. As demonstrated by numerical data calculated for a series of simple molecules by the semiempirical MNDO method, the resulting populations provide a new simple means of visualizing the molecular structure. In addition to the reproduction of classical structural formula including the multiplicity of individual bonds, the resulting populations confirm the transferability of bond energies and also provide a simple interpretation of the concept of quantum chemical valence. © 1994 John Wiley & Sons, Inc.     

Stereocontrolled access to isoprostanes via a bicyclo[3.3.0]octene framework

We report a simple and highly stereocontrolled strategy toward the total synthesis of isoprostanes based on a bicyclic alpha,beta-epoxy ketone intermediate 6. Bicyclo[3.3.0]octene scaffold permitted stereodirection of reagents allowing stereoselective epoxidation, diastereoselective ketone reduction, and regioselective epoxide opening otherwise not accessible with a simple cyclopentene framework.     

Interlayer Bond Formation in Black Phosphorus at High Pressure

Black phosphorus was compressed at room temperature across the A17, A7 and simple‐cubic phases up to 30 GPa, using a diamond anvil cell and He as pressure transmitting medium. Synchrotron X‐ray diffraction showed the persistence of two previously unreported peaks related to the A7 structure in the pressure range of the simple‐cubic phase. The Rietveld refinement of the data demonstrates the occurrence of a two‐step mechanism for the A7 to simple‐cubic phase transition, indicating the existence of an intermediate pseudo simple‐cubic structure. From a chemical point of view this study represents a deep insight on the mechanism of interlayer bond formation during the transformation from the layered A7 to the non‐layered simple‐cubic phase of phosphorus, opening new perspectives for the design, synthesis and stabilization of phosphorene‐based systems. As superconductivity is concerned, a new experimental evidence to explain the anomalous pressure behavior of T_c in phosphorus below 30 GPa is provided.     

反对数简易示波伏安法的研究

本文在产生简易示波伏安曲线的实验线路中增加了反对数线路，提出了反对数简易示波伏安法，用此方法进行了络合滴定及实际样品的测定，结果符合分析要求。     

简易示波伏安曲线的研究

本文提出了一种示波滴定的新方法——简易示波伏安法,该法克服了双电解池i_t-E曲线仪器复杂、操作麻烦等缺点,使用单电解池和一个很简单的线路也可以获得示波伏安图,具有广泛的应用价值。适宜于药物分析。     

Chemoselective hydrosilylation of hydroxyketones

A chemoselective method for the hydrosilylation of ketones has been developed, using the combination of triphenylsilane and a catalyst prepared from Ni(COD)₂ and the simple N-heterocyclic carbene IMes. The most notable feature of this method is that free hydroxyls are largely unaffected, thus providing a simple one-step procedure for the conversion of hydroxyketones to mono-protected diols, wherein the protecting group is exclusively installed on the ketone-derived hydroxyl. The process is typically high yielding with both simple ketones and more complex hydroxyketone substrates.