Half-metallic digital ferromagnetic heterostructure composed of a delta-doped layer of Mn in Si

We propose and investigate the properties of a digital ferromagnetic heterostructure consisting of a delta-doped layer of Mn in Si, using ab initio electronic-structure methods. We find that (i) ferromagnetic order of the Mn layer is energetically favorable relative to antiferromagnetic, and (ii) the heterostructure is a two-dimensional half-metallic system. The metallic behavior is contributed by three majority-spin bands originating from hybridized Mn-d and nearest-neighbor Si-p states, and the corresponding carriers are responsible for the ferromagnetic order in the Mn layer. The minority-spin channel has a calculated semiconducting gap of 0.25 eV. The band lineup is found to be favorable for retaining the half-metal character to near the Curie temperature. This kind of heterostructure may be of special interest for integration into mature Si technologies for spintronic applications.     

A phase field approach to shape optimization in Navier–Stokes flow with integral state constraints

We consider the shape optimization of an object in Navier–Stokes flow by employing a combined phase field and porous medium approach, along with additional perimeter regularization. By considering integral control and state constraints, we extend the results of earlier works concerning the existence of optimal shapes and the derivation of first order optimality conditions. The control variable is a phase field function that prescribes the shape and topology of the object, while the state variables are the velocity and the pressure of the fluid. In our analysis, we cover a multitude of constraints which include constraints on the center of mass, the volume of the fluid region, and the total potential power of the object. Finally, we present numerical results of the optimization problem that is solved using the variable metric projection type (VMPT) method proposed by Blank and Rupprecht, where we consider one example of topology optimization without constraints and one example of maximizing the lift of the object with a state constraint, as well as a comparison with earlier results for the drag minimization.     

β-环糊精与萘普生的包络反应及荧光分析

采用荧光光谱法系统地研究了萘普生的自身荧光现象及其与β-环糊精因包络反应而产生的荧光增敏作用,试验了在不同条件下的荧光性质,提出了测定萘普生含量的高灵敏荧光光度分析新方法. 荧光激发峰λex =229 nm ,荧光发射峰λem = 353 nm ,荧光强度(F)与萘普生的浓度在6.14×10- 8m ol·L- 1 ～1.36×10- 5m ol·L- 1范围内呈线性关系,分析方法操作简便、快速,重现性好,结果令人满意.     

New synthetic technology for the synthesis of hindered alpha-diazoketones via acyl mesylates

[formula: see text] A mild and reliable one-pot protocol for the elaboration of sterically demanding carboxylic acids into alpha-diazoketones via acyl mesylates has been developed. Aside from delineating the reaction parameters which render this strategy quite general for hindered carboxylic acids, we have directly proven the existence of the fleeting acyl mesylate group as the reactive species in these reactions and shed light onto the differing mechanisms which are operative in the activation of hindered and simple carboxylic acids with methanesulfonyl chloride.     

The semigroup generated by a similarity orbit or a unitary orbit of an operator

Let be an invertible operator that is not a scalar modulo the ideal of compact operators. We show that the multiplicative semigroup generated by the similarity orbit of is the group of all invertible operators. If, in addition, is a unitary operator, then the multiplicative semigroup generated by the unitary orbit of is the group of all unitary operators.

     

Structure‐Based Design and Synthesis of Regioisomeric Disubstituted Aminoanthraquinone Derivatives as Potential Anticancer Agents

Continuing our ongoing studies on cytotoxic substances, we report the synthesis and cytotoxic properties of a series of symmetric 1,5‐diamino‐9,10‐anthraquinones with potentially bioreducible groups. Symmetric amination of 1,5‐dichloro‐9,10‐anthraquinone with the appropriate primary amines in the presence of DMF furnished the structurally related aminoanthraquinone analogs 1 – 19 . Their in vitro cytotoxic activity was evaluated using rat glioma C6 cells, human hepatoma G2 cells, and 2.2.15 cells. Several compounds exhibited very high antitumor activities in these assays. Compound 4 efficiently inhibited C6 cells, human hepatoma G2 cells, and 2.2.15 cells, as determined by means of the XTT colorimetric assay. The antiproliferative activity of 4 was markedly enhanced, reaching a potency comparable to those of the powerful anticancer agents mitoxantrone, adriamycin, and cisplatin. Biological evaluations and structure/activity relationships within this class of novel aminoanthraquinones are discussed.     

LECTIN RECEPTORS ON ROD AND CONE MEMBRANES

Abstract— The oligosaccharides of rod and cone membranes were investigated with the aid of fluorescence and ¹²⁵I-labeled lectins. Additionally, the ability of lectins to cause agglutination in rod outer segment (ROS) suspensions was used as an index for the presence of the corresponding lectin receptors. The specificities of lectin-ligand interactions were determined from studies of inhibition by various haptene sugars. The membranes of both rods and cones have receptors for Con A, PNA, RCA-120, RCA-60, SBA and WGA. The affinity of PNA for accessory cones is much higher than for the principal cones. There do not appear to be receptors for UeA and LTA on rods or cones. Additionally, receptors for HPA and DBA were identified on ROS. These results suggest the existence of the following sugar residues:

The binding of Con A and WGA to ROS membrane proteins electrophoresed on SDS-polyacrylamide gels was also investigated. In addition to rhodopsin, these lectins also bind to the 291000-dalton protein, indicating that it is a glycoprotein containing mannose and GlcNAc.     

New amphiphilic silicon(IV) phthalocyanines as efficient photosensitizers for photodynamic therapy: synthesis, photophysical properties, and in vitro photodynamic activities

A novel series of silicon(IV) phthalocyanines substituted axially with one or two 1,3-bis(dimethylamino)-2-propoxy group(s) have been prepared by ligand substitution and alkoxy exchange reactions. Two dicationic and tetracationic phthalocyanines have also been prepared by methylation of two of these compounds. The nonionic phthalocyanines are essentially nonaggregated in common organic solvents and show a weak fluorescence emission, while the methylated derivatives are also nonaggregated, even in aqueous media, and exhibit a strong fluorescence emission. These new phthalocyanines, in particular the unsymmetrical and amphiphilic analogues, are highly potent against HepG2 human hepatocarcinoma cells and J774 mouse macrophage cells with IC50 values down to 0.02 microM. The photodynamic activities are related to the cellular uptake and the efficiency to generate singlet oxygen. A higher positive charge at the phthalocyanine hinders the uptake, reflected by the lower intracellular fluorescence intensity. Fluorescence microscopic studies have also revealed that the unsymmetrical phthalocyanine SiPc[C3H5(NMe2)2O](OMe) (4) has a high and selective affinity to the mitochondria of HepG2 cells.     

Synthesis,characterization and X-ray crystal structures of the bis–ligand zinc(II) and cadmium(II) complexes of the methylpyruvate Schiff base of <Emphasis Type="Italic">S</Emphasis>-methyldithiocarbazate

New bis-chelated Zn^II and Cd^II complexes of empirical formula, [M(mpsme)₂] (mpsme=the anionic form of the tridentate ONS donor ligand formed from methylpyruvate and S-methyldithiocarbazate) have been prepared and characterized by conductance, i.r., electronic and n.m.r. spectroscopic techniques. Spectral evidence supports a six-coordinate distorted octahedral structure for these complexes. X-ray crystallographic structural analysis also confirms that, in both the [Zn(mpsme)₂] and [Cd(mpsme)₂] complexes, the methylpyruvate Schiff base of S-methyldithiocarbazate is coordinated to the metal ions as a uninegatively charged tridentate ONS chelating agent via the carbonyl oxygen atom, the azomethine nitrogen atom and the thiolate sulfur atom. Both complexes are assigned a distorted octahedral geometry in which the ligands are arranged meridionally around the metal ions. The distortion from regular octahedral geometry is attributable to the restricted bite angles of the ligand.     

Determination of trace elements in food by neutron activation analysis

Neutron activation analysis (NAA) methods have been developed for the determination of major, minor and trace elements in duplicate diets and individual food items. These include a cyclic instrumental NAA (CINAA) method for measuring Se content through its short-lived nuclide^77mSe; epithermal INAA (EINAA) for I and As; conventional INAA for Br, Ca, Cl, Co, Cr, Fe, K, Mg, Mn, Na, Rb, Sb, Sc, Sn and Zn; combination of EINAA and INAA for Al; radiochemical NAA (RNAA) for As, Au, Co, Cu, Fe, Hg, Mo, Sb, Se and Zn; and preconcentration NAA (PNAA) for U and Th. Accuracy of measurements have been evaluated by analyzing a number of biological and diet reference materials. Multielement concentrations of diets and foods have been measured by these methods.