Synthesis of amphiphilic triblock copolymer of polystyrene and poly(4-vinylbenzyl glucoside) via TEMPO-mediated living radical polymerization

4-Vinylbenzyl glucoside peracetate 1 was polymerized with α,α′-bis(2′,2′,6′,6′-tetramethyl-1′-piperidinyloxy)-1,4-diethylbenzene 2 in chlorobenzene using (1S)-(+)-10-camphorsulfonic acid anhydrous (CSA) as an accelerator ([1]=0.4 M,[1]/[2]/[CSA]=75/1/1.3) at 125 °C for 5 h. The polymerization afforded poly(4-vinylbenzyl glucoside peracetate) having TEMPO moieties on both sides of the chain ends, 3, with a molecular weight (M_w,SLS) of 8500, a polydispersity index (M_w/M_n) of 1.09, and an average degree of polymerization of the 1 unit (x) of 17. Styrene (St) was polymerized with 3 in chlorobenzene at 125 °C (St/chlorobenzene=1/2, w/w). The polymerization successfully afforded polystyrene-poly(4-vinyl glucoside peracetate)-polystyrene, 4, when the polymerization time was below about 2 h. Polymer 4 with the M_w,SLS of 12,500, 17,900, and 29,400, the compositions (y-x-y) of 20-17-20, 45-17-45, and 100-17-100, and the M_w/M_n of 1.12, 1.14 and 1.17 were modified by deacetylation using sodium methoxide in dry-THF into polystyrene-poly(4-vinyl glucoside peracetate)-polystyrene, 5. The solubility of polymer 5 was examined using a good solvent for polystyrene such as toluene and for the saccharide such as H₂O.     

Properties of Nitrogen-Containing Yttria—Alumina—Silica Melts and Glasses

The viscosity and solubility of nitrogen in Y₂O₃–Al₂O₃–SiO₂ melts have been systematically examined. The effects of nitrogen content on viscosity for Y-Al-Si-O-N melts and on Vickers hardness of oxynitride glasses also have been examined. Although the viscosity of Y₂O₃–Al₂O₃–SiO₂ melts was decreased, the solubility of nitrogen into the melts was increased with increased Y₂O₃ content. These results indicated that the yttrium ion behaved as a network modifier. Therefore, the structural units for viscous flow became small, and the amount of nonbridging oxygen increased in the melts when the Y₂O₃ content increased. The viscosity of Y-Al-Si-O-N melts and Vickers hardness of oxynitride glasses remarkably increased with increased nitrogen content. These results suggested that the substitution of nitrogen for oxygen in the melts may have led to a high average coordination of nonmetal atoms and that the increased cross-linking produced a more rigid glass network.     

Effect of Long Chain Fatty Acids on Organocatalytic Aqueous Direct Aldol Reactions

In an organocatalyzed, aqueous direct aldol reaction, the addition of a long chain fatty acid (1 mol%) such as stearic acid or erucic acid improved the aldol product yield and the enantioselectivity with low catalyst loading (1 mol%). The small particle size of the emulsion (less than 1 μm) was a key to the enhanced reactivity as shown by dynamic light scattering (DLS) analyses.     

Synthesis and characterization of polyamides based on cubane-1,4-dicarboxylic acid

The direct polycondensations of cubane-1,4-dicarboxylic acid with 1,4-phenylenediamine (2 a), 4,4′-oxydianiline (2 b), 4,4′-sulfonyldianiline (2 c), and 9,9′-bis(4-aminophenyl)florene (2 d) were carried out in N-methyl-2-pyrrolidone/pyridine containing triphenylphosphite and lithium chloride at 110 °C for 9 h. Polyamide 3 a obtained from 2 a was scarcely soluble in organic solvent even during heating, and was soluble only in conc-H₂SO₄, whereas 3 c and 3 d derived from 2 c and 2 d, respectively, were readily soluble in N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and dimethylsulfoxide. After treating polyamide 3 d with the rhodium complex catalyst in NMP, cubane units were quantitatively converted into cyclooctatetraenes. Received: 3 March 1997/Accepted: 1 April 1997     

Temperature effect on microchannel oil-in-water emulsification

Microchannel (MC) emulsification is a promising technique to produce monodisperse emulsions by spontaneous interfacial-tension-driven droplet generation. The purpose of this study was to systematically characterize the effect of temperature on droplet generation by MC emulsification, which is a major uncharted area. The temperature of an MC emulsification module was controlled between 10 and 70°C. Refined soybean oil was used as the dispersed phase and a Milli-Q water solution containing sodium dodecyl sulfate (1 wt%) as the continuous phase. Monodisperse oil-in-water (O/W) emulsions with a coefficient of variation below 4% were produced, and at all the operating temperatures, their average droplet diameter ranged from 32 to 38 μm. We also investigated the effect of flow velocity of the dispersed phase on droplet generation characteristics. The maximum droplet generation rate (frequency) from a channel at 70°C exceeded that at 10°C by 8.1 times, due to the remarkable decrease in viscosity of the two phases. Analysis using dimensionless numbers indicated that the flow of the dispersed phase during droplet generation could be explained using an adapted capillary number that includes the effect of the contact angle of the dispersed phase to the chip surface.     

A case report of selective IgA deficiency in rheumatoid arthritis and anti-IgA antibody induced anaphylactic transfusion]

Recurrent respiratory papillomatosis (RRP), usually confined to the nasopharynx, trachea, and larynx, occasionally can progress to extensive bronchopulmonary disease. Most cases of bronchopulmonary and laryngeal papillomatosis are cytologically benign and do not undergo malignant transformation; however, squamous cell carcinoma (SCC) can arise in RRP in the absence of known risk factors such as radiation and smoking. In this study, the authors investigated molecular genetic alterations occurring in a case of metastasizing SCC that arose in long-standing bronchopulmonary papillomatosis. Genomic DNA from tracheal papillomata, tracheobronchial papillomata, SCC of the lung, and a lymph node metastasis was extracted. The physical state of the human papillomavirus type 11 (HPV-11) DNA was investigated by two-dimensional gel electrophoresis. Molecular genetic alterations of the host genome were studied by direct sequencing of polymerase chain reaction-amplified gene fragments and restriction fragment length polymorphism (RFLP) analysis. Episomal and integrated forms of HPV-11 sequences were detected in histologically benign tumors, but only the integrated form of the viral DNA could be found in malignant tissue samples. Molecular genetic studies revealed that an allelic loss of the interferon-beta gene (IFNbeta-1) and an endogenous type of mutation of the p53 antioncogene were found only in the malignant lesions. Mutations were not observed in the ras, neu, or multiple tumor suppressor (MTS1/p16) genes in any specimens. The authors' data indicated that the p53 genetic mutation was associated with integration of HPV-11 in histologically malignant lesions. This association may promote a progressive genetic instability that can lead to the development and clonal expansion of malignant lesions in RRP.     

Verifying a signature architecture: a comparative case study

We report on a case study in applying different formal methods to model and verify an architecture for administrating digital signatures. The architecture comprises several concurrently executing systems that authenticate users and generate and store digital signatures by passing security relevant data through a tightly controlled interface. The architecture is interesting from a formal-methods perspective as it involves complex operations on data as well as process coordination and hence is a candidate for both data-oriented and process-oriented formal methods. We have built and verified two models of the signature architecture using two representative formal methods. In the first, we specify a data model of the architecture in Z that we extend to a trace model and interactively verify by theorem proving. In the second, we model the architecture as a system of communicating processes that we verify by finite-state model checking. We provide a detailed comparison of these two different approaches to formalization (infinite state with rich data types versus finite state) and verification (theorem proving versus model checking). Contrary to common belief, our case study suggests that Z is well suited for temporal reasoning about process models with complex operations on data. Moreover, our comparison highlights the advantages of proving theorems about such models and provides evidence that, in the hands of an experienced user, theorem proving may be neither substantially more time-consuming nor more complex than model checking.     

Role of Cooling Process in the Thermal Aggregate Formation by Carp Myosin Rod

Carp myosin rod solution did not show detectable turbidity upon heating at 80 °C. Rod aggregation was detected only by high sensitive light scattering intensity and gel filtration analysis on Sepharose CL 4B. Roughly half of myosin rod was still monomeric for sample heated at 80 °C at 2 mg/mL. Prolonged heating at 80 °C did not increase the amount of aggregates. Aggregation was prominent at high concentration of rod. Rod aggregation was promoted by cooling of the heated rod solution. Heating at 80 °C completely unfolded the α‐helix structure of rod. However, α‐helix structure was significantly recovered by about 85% upon cooling. Unfolding and aggregation analysis revealed that complete unfolding of whole rod structure was needed for aggregation, and the cooling process accompanying refolding of helical structure was important for aggregate formation.     

No. 4Vol. 42, No. 2, pp. 102–109, 2008A novel water-based sunscreen gel using a polymer – zinc oxide composite

Conventional sunscreen products generally must strike a compromise between efficacy and product feel; the hydrophobic ingredients that provide the sun protection generally impart an unpleasant, greasy feel and the greater the SPF rating, the worse the greasy feel. We tested an idea that a water-based sunscreen gel formulation containing inorganic UV absorbers would provide an effective way to address these problems. Our goal was to find a way to disperse inorganic sunscreen materials in water and to incorporate them into a water-based gel which would provide a more pleasant product feel. After extensive research we discovered a polymer-zinc oxide composite (P-ZnO) with high UV protective effect and high dispersibility in water. In dried powdered form, P-ZnO can be easily dispersed in water. P-ZnO makes it possible to formulate a gel-type sunscreen, which is not possible using commercially available inorganic powders. The composite size of P-ZnO is about 500 nm and its structure consists of a dense aggregate of nano-ZnO having a size distribution in the 5–10 nm range and amorphous layers of poly acrylic acid coating zinc oxide to control the particle growth, block surface activity and prevent aggregation. The water-based P-ZnO sunscreen gel offers UV protection comparable to conventional products in a delivery vehicle that is much more pleasant to use.