Increased covalent conjugation of a model antigen to poly(lactic acid)-g-maleic anhydride nanoparticles compared to bare poly(lactic acid) nanoparticles

Maleic anhydride (MA) grafted poly(lactic acid) (PLA) (PLA-g-MA) was synthesized from PLA. Proton nuclear magnetic resonance confirmed the grafting of the MA. PLA-g-MA and PLA were used to prepare polymeric nanoparticles. Particle size distributions were measured by dynamic light scattering, and colloidal stability was determined by (zeta) ζ-potential. The ζ-potential becomes more negative for PLA-g-MA than PLA nanoparticle dispersions, due to the presence of deprotonated carboxylic acid groups on the backbone of the PLA and confirms the MA grafting results. Maleic anhydride grafted on PLA backbone improves the covalent conjugation with ovalbumin (OVA) compared to OVA physically adsorbed on the particles. The chemical conjugation was carried out via amide linkages between the carboxylic groups of the nanoparticles, activated with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and the amino groups of the protein. The amount of protein conjugated was measured by using the bicinchoninic acid method and is threefold higher compared to the adsorbed OVA. Moreover, the PLA-g-MA nanoparticles increased the amount of conjugated OVA by 36 wt% compared to PLA nanoparticles. OVA adsorption and OVA conjugation provided colloidal dispersions with excellent stability.     

Square-planar iridium(II) and iridium(III) amido complexes stabilized by a PNP pincer ligand

Squaring the circle: the novel dienamido pincer ligand N(CHCHPtBu(2))(2)(-) affords the isolation of the unusual square-planar iridium(II) and iridium(III) amido complexes [IrCl{N(CHCHPtBu(2))(2)}](n) (n=0 (1), +1 (2)). In contrast, the corresponding iridium(I) complex of the redox series (n=-1) is surprisingly unstable. The diamagnetism of 2 is attributed to strong N→Ir π donation.     

A novel method for the synthesis of polystyrene-graft-silica particles using random copolymers based on styrene and triethoxyvinylsilane

In the present research, random copolymers based on triethoxyvinylsilane (TEVS) and styrene (St) are synthesized and structurally characterized. According to the reactivity ratios of the monomers determined by infrared analysis; St tends to form blocks whilst TEVS is expected to be incorporated as isolated units. A sample of poly(styrene-co-triethoxyvinylsilane) synthesized at low conversion using a monomer feeding ratio St:TEVS of 2:3 was used as macrosilane in the synthesis of polystyrene-g-silica particles. The grafting reaction was confirmed by infrared spectroscopy, thermogravimetric analysis and by the evaluation of the morphological characteristics of the hybrid particles.     

Studies on grain boundary effects in spray deposited BICOVOX 0.1 films on platinum-coated stainless steel substrate

Thin film of Bi₂Co_0.1V_0.9O_5.35 is deposited by using spray pyrolysis technique on platinum-coated stainless steel substrate. Impedance measurements done in the frequency range 1 to 10 MHz and in the temperature range 502 to 720 K revealed two relaxation processes with distinguishable time constants. The first corresponds to the grain interior charge transfer while the second could be due to grain boundary. The change in polarization seems to be associated with hopping of charge carriers showing Arrhenius behavior with increase in temperature. The relaxation frequency of grain interior transport for the thin film ranges from 96 kHz to 2.59 MHz. The blocking factor was found to be increasing with increase in temperature at low temperature region from 502 to 640 K. At higher temperature above 640 K, diffusive nature of grain boundaries is inferred with the decrease in blocking factor. The same inference is derived by specific grain boundary conductivity calculations since specific grain boundary conductivity decreases in low temperature region while it increases rapidly at higher temperature. These observations prove the grain boundaries to be blocking in lower temperatures while at higher temperatures above 640 K they turn diffusive. These changes are attributed to structural phase transition, or ordering of vacancies in Bi₂Co_0.1V_0.9O_5.35 films.     

Möbius disjointness for models of an ergodic system and beyond

Given a topological dynamical system (X, T) and an arithmetic function u: ? → ?, we study the strong MOMO property (relatively to u) which is a strong version of u-disjointness with all observable sequences in (X, T). It is proved that, given an ergodic measure-preserving system (Z, \(\mathcal{D}\), к, R),the strong MOMO propertly (relately to u) of a uniquely ergodic midel (X, T)of R yields all other uniquely ergodic midel of R to be u-disjiont. It follows that all uniquely ergodic models of: ergodic unipotent diffeomorphisms on nilmanifolds, discrete spectrum automorphisms, systems given by some substitutions of constant length (including the classical Thue—Viorse and Rudin—Shapiro substitutions), systems determined by Kakutani sequences are Möbius (and Liouville) disjoint. The validity of Sarnak5s conjecture implies the strong MOMO property relatively to μ in all zero entropy systems; in particular, it makes μ-disjointness uniform. The absence of the strong MOMO property in positive entropy systems is discussed and it is proved that, under the Chowla conjecture, a topological system has the strong MOMO property relatively to the Liouville function if and only if its topological entropy is zero.     

稀土掺杂硅基薄膜的高效发光特性

测量了在不同离子注入剂量,不同退火条件下的Nd注入Si基晶片室温光致发光谱,结果表明它们均具有蓝、紫发光峰,且发光稳定。在一定范围内发光效率随掺杂浓度的增加而增大,随退火条件的不同而改变。在实验室条件下,对掺杂硅片和单晶硅片进行电化学腐蚀制成多孔硅样片,同时用适当配比的HNO3对以单晶硅为基底的多孔硅进行处理,测试了腐蚀后各类样品的光致发光（PL）谱。发现掺稀土Nd的多孔硅和用HNO3处理的多孔硅的发光效率有显著提高。     

The heteroscorpionate ligand 2,2‐bis(3,5‐dimethylpyrazol‐1‐yl)‐1,1‐diphenylethanol and an easy preparation of its tungsten complex

The heteroscorpionate ligand 2,2‐bis(3,5‐dimethylpyrazol‐1‐yl)‐1,1‐diphenylethanol, C₂₄H₂₆N₄O, features in the solid state an intramolecular O—H…N hydrogen bond. A heteroscorpionate tungsten complex, cis‐[2,2‐bis(3,5‐dimethylpyrazolyl)‐1,1‐diphenylethanolato]chloridodioxidotungsten(VI) tetrahydrofuran monosolvate, [W(C₂₄H₂₅N₄O)ClO₂]·C₄H₈O, was prepared by the simple mixing of solutions of the ligand and WOCl₄ in tetrahydrofuran. The tungsten complex was isolated after standing for several weeks. The complex exhibits a κ³N,N′,O‐coordination of the ligand. This simple synthetic procedure allows access to the cis isomer in high yield without additional purification steps. The Hirshfeld surface analysis shows a change of the intermolecular contacts due to the coordination of the WO₂Cl unit with the ligand molecule.     

Strongest postcondition semantics as the formal basis for reverse engineering

Reverse engineering of program code is the process of constructing a higher level abstraction of an implementation in order to facilitate the understanding of a system that may be in a “legacy” or “geriatric” state. Changing architectures and improvements in programming methods, including formal methods in software development and object-oriented programming, have prompted a need to reverse engineer and re-engineer program code. This paper describes the application of the strongest postcondition predicate transformer (sp) as the formal basis for the reverse engineering of imperative program code. This work is supported in part by the National Science Foundation grants CCR-9407318, CCR-9209873, and CDA-9312389. This author is supported in part by a NASA Graduate Student Researchers Program Fellowship.