Core Cross-Linked Amphiphilic Star-Block Copolymers with (Meth)acrylic Acid Shells Prepared by Atom Transfer Radical Polymerization

Core cross-linked amphiphilic star-block copolymers were prepared by hydrolysis of the outer shell of star-block copolymers prepared using copper mediated atom transfer radical polymerization (ATRP). In an arm-first approach, linear poly(tert-butyl methacrylate) macroinitiators (PtBMA-Cl) were extended with styrene to yield PtBMA-b-PS-Cl and then cross-linked with divinylbenzene (DVB) in order to yield (PtBMA-b-PS)_arms-PDVB_core star-block copolymers. Then, PMAA-b-PS block and (PMAA-PS)_arms-PDVB_core star-block copolymers were obtained by hydrolysis of the PtBMA blocks in both linear and cross-linked copolymers, as confirmed by ¹H NMR analyses. The amphiphilic character of these copolymers was confirmed by solubilisation in water. Several factors affecting the polymer aggregation and solubility such as the length, the composition of the arms and the catalyst used were studied. An acrylate analogue, that is, (PAA-b-PS)_arms-PDVB_core, was also prepared for comparison purposes. Atomic force microscopy (AFM) and differential scanning calorimetry (DSC) were used to elucidate the morphology and the thermal behaviour of the star-block copolymers.     

System for production of high and low protein dispersibility index edible extracted soybean flakes

A standard flash desolventizing system has been combined with horizontal agitated meal stripping and cooking vessels operating at atmospheric pressure to provide an integrated system for the production of high, intermediate, or low protein dispersability index edible soybean flakes from extracted solvent-wet flakes. Flash desolventizing removes most of the hexane in the wet flakes by evaporation at low temperature in a turbulent stream of superheated hexane vapor. The small remaining hexane quantity is removed in a stripping process capable of producing the full range of protein dispersability index values in the flakes by treating the flash desolventized flakes with either dry superheated steam or wet saturated steam under carefully controlled conditions of steam temperature, pressure, flow rate, and moisture content. The products are light colored, with little production of fine particles. One of seven papers presented at the symposium “Processing Methods for Oilseeds,” AOCS Spring Meeting, April 1973.     

Thirteen-year evolution of azole resistance in yeast isolates and prevalence of resistant strains carried by cancer patients at a large medical center

Drug resistance is emerging in many important microbial pathogens, including Candida albicans. We performed fungal susceptibility tests with archived isolates obtained from 1984 through 1993 and fresh clinical isolates obtained from 1994 through 1997 by testing their susceptibilities to fluconazole, ketoconazole, and miconazole and compared the results to the rate of fluconazole use. All isolates recovered prior to 1993 were susceptible to fluconazole. Within 3 years of widespread azole use, we detected resistance to all agents in this class. In order to assess the current prevalence of resistant isolates in our hematologic malignancy and transplant patients, we obtained rectal swabs from hospitalized, non-AIDS, immunocompromised patients between June 1995 and January 1996. The swabs were inoculated onto sheep's blood agar plates containing 10 microg of vancomycin and 20 microg of gentamicin/ml of agar. One hundred one yeasts were recovered from 97 patients and were tested for their susceptibilities to amphotericin B, fluconazole, flucytosine, ketoconazole, and miconazole. The susceptibility pattern was then compared to those for all clinical isolates obtained throughout the medical center. The antifungal drug histories for each patient were also assessed. The yeasts from this surveillance study were at least as susceptible as the overall hospital strains. There did not appear to be a direct linkage between prior receipt of antifungal agent therapy and carriage of a new, drug-resistant isolate. Increased resistance to newer antifungal agents has occurred at our medical center, but it is not focal to any high-risk patient population that we studied. Monitoring of susceptibility to antifungal agents appears to be necessary for optimizing clinical therapeutic decision making.     

Combined effects of chitosan and MAP to improve the microbial quality of amaranth homemade fresh pasta

In this work a study on the combined effects of chitosan and modified atmosphere packaging (MAP) to improve the microbiological quality of amaranth-based homemade fresh pasta is presented. In particular, two different chitosan concentrations were combined to three different MAP conditions and tested against the following spoilage microorganisms: mesophilic bacteria, Staphylococcus spp., yeasts, moulds and total coliforms. Their viable cell concentrations were monitored for about 2 months at 4 °C. Results suggest that there is a combined effect between MAP and chitosan in delaying the microbial quality loss of pasta during storage. Moreover, it was also found that among the tested MAP conditions, the combination of 30:70 N₂:CO₂ is the most efficient, promoting an extension of the microbial acceptability limit beyond two months.     

Electrooptical Modulating Device Based on a CMOS-Compatible -Si:H/ -SiCN Multistack Waveguide

In this paper, we report results on a field-effect-induced light modulation at $lambda$ $=$ 1.55 $mu$m in a high-index-contrast waveguide based on a multisilicon-on-insulator platform. The device is realized with the hydrogenated amorphous silicon ($alpha$ -Si:H) technology, and it is suitable for monolithic integration in a CMOS IC. The device exploits the free-carrier optical absorption electrically induced in the semiconductor core waveguide. The amorphous silicon waveguiding layer contains several thin dielectric films of amorphous silicon carbonitride ($alpha$ -SiCN) embedded along its thickness, thus highly enhancing the absorbing action of the modulator held in the on state.      

Influence of repeated extrusions on some properties of non-conventional spaghetti

The influence of the re-extrusion (repeated extrusion) number on the rheological properties of non-conventional doughs, mechanical and sensorial characteristics of dry spaghetti was investigated. Moreover, the dough gelatinization degree was also evaluated. Amaranth, oat and quinoa flours were used to produce the spaghetti samples. Twelve non-conventional spaghetti samples were manufactured varying the re-extrusion number. The rheological properties of doughs were determined using a capillary rheometer, the mechanical characteristics of dry spaghetti by a dynamic mechanical analyzer and the sensorial parameters by a trained panel. The re-extrusion number affected the extensional and shears viscosity of amaranth, oat and quinoa dough samples. The breaking strength of dry non-conventional spaghetti increased with the increase of the re-extrusion number for amaranth and oat. The dough gelatinization degree of the quinoa and oat significantly increased with the re-extrusion, whereas no influence of re-extrusion was found for the amaranth dough. Moreover, the re-extrusion number improved sensorial color and homogeneity for oat and quinoa dry spaghetti and had no effects on the sensorial characteristics of all cooked spaghetti.     

Variable reluctance motor structures for low-speed operation

The static torque capability of three competing variable reluctance motors is compared in order to identify which structure is best suited for low-speed operation. Linear analysis is the basis of the comparison between a conventional switched reluctance motor, a variable reluctance motor with mutually coupled windings, and a variable reluctance motor with anisotropic rotor. End turn and multipole effects are considered. The impact of saturation is considered by comparing static torque computed with finite element models. This analysis provides the rationale for choosing one configuration over another under fixed voltage and current limit constraints. The alternative constructions are shown to have potential for significant improvement in static torque under certain conditions     

Sequential monitoring of surface spatial variation in automotive machining processes based on high definition metrology

The ability to monitor machining processes within micron level is critical to high precision manufacturing. New non-contact measurement technology, such as holography based high definition metrology (HDM), makes this feasible through monitoring of both the part shape and its surface texture. However, conventional statistical process monitoring and diagnostic schemes based on low definition measurement technology have limitations in addressing the HDM data since such data are in high-dimensional form and may show strong spatial correlation. Based on a previously published sequential strategy for global and localized monitoring of shape variations in HDM data, this paper improves the method by refining the localized monitoring scheme, and applies the method to HDM data collected from an automotive engine head machining process. The results show that the proposed HDM monitoring scheme can effectively localize the defective regions on the out-of-control parts.     

Near-visible stereolithography of a low shrinkage cationic/free-radical photopolymer blend and its nanocomposite

In this work, a newly prepared cationic/free-radical photopolymer, which consists of two epoxies and a tetrafunctional acrylate, is presented for the first time for a visible light stereolithography (SL), showing the advantages of both cationic and free-radical resins. An onium salt, commonly used as a cationic UV initiator, and a photosensitizer make the blend suitable for a near-visible (405 nm) SL. An increase in the polymerization rate and a drop in the induction period are observed for the newly prepared cationic/free-radical blend, compared with either only cationic systems or free-radical resins. This suggests that the combination of cationic and free-radical polymerizations in a single resin has a positive synergistic effect. The addition of silica nanoparticles to the blend provides a reinforcing and toughening effect. Indeed, the resin loaded with silica shows a 31% increase in the elastic modulus, compared with the unfilled resin. Regarding the values of tensile strength and elongation at break, they, respectively, grow by 47 and 15%, when the nanocomposite resin is compared with the neat resin. A very low volumetric shrinkage of 0.7% and a remarkable printing quality of objects obtained with this new photopolymer will enable the 3D printing of microrobots, bioengineering microdevices, and sensors. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48333.