Optimization of Feedback FET with Asymmetric Source Drain Doping Profile.

A feedback field-effect transistor (FBFET) is a novel device that uses a positive feedback mechanism. FBFET has a high on-/off ratio and is expected to realize ideal switching characteristics through steep changes from off-state to on-state. In this paper, we propose and optimize FBFET devices with asymmetric source/drain doping concentrations. Additionally, we discuss the changes in electrical characteristics across various channel length and channel thickness conditions and compare them with those of FBFET with a symmetric source/drain. This shows that FBFET with an asymmetric source/drain has a higher on-/off ratio than FBFET with a symmetric source/drain.

Fabrication of microgrooves on a curved surface by the confocal measurement system using pulse laser and continuous laser.

In order to fabricate microgrooves on a curved surface, the curved surface was measured with a confocal system and then it was used for laser microprocessing. This paper proposes a new method of using a pulse laser for the confocal system to measure the curved surface. It also compares the conventional way of using a continuous laser and a new way of using the pulse laser with the confocal system. Using the data measured with the pulse laser for fabrication, microgrooves were fabricated on a curved surface. The width of the fabricated microgroove was 10 µm and the depth was 27 µm. The microgroove fabricated on a curved surface as a part of this study can be used in injection molding to manufacture a micropatterned plastic surface at a low cost. This plastic surface can be applied for a superhydrophobic surface, a self-cleaning surface, or a biochip.

Characterization of sodium hyaluronate blends using frit inlet asymmetrical flow field-flow fractionation and multiangle light scattering.

We characterized ultrahigh molecular weight sodium hyaluronate (NaHA) and blended pharmaceutical products containing NaHA using flow field-flow fractionation and multiangle light scattering-differential refractive index (FlFFF-MALS-DRI). NaHA is a water-soluble polysaccharide with a range of molecular weights (MW; 10(5)~10(8) Da) that is found in body fluids and tissues. NaHA is also used commercially in pharmaceutical and cosmetic applications. We used a frit inlet asymmetrical FlFFF channel to separate aqueous polymers according to their hydrodynamic size, and we used on-line measurements of light scattering to obtain the MW distribution (MWD) as well as structural information about NaHA in aqueous solution. In this study, we investigated NaHA and anti-adhesive blend mixtures of NaHA (a commercial NaHA blend mixture containing sodium carboxymethyl cellulose and a new blend with hydroxyethyl starch (HES)) to determine the molecular weight distribution MWD of NaHA and the blend mixtures and to obtain structural information about these compounds in aqueous solution. We also examined the characteristics of NaHA-HES-polylactic-co-glycolic acid film products exposed to gamma radiation for sterilization purposes.

New phytopharmaceutical agent CJ-20001 modulates stress-induced inflammatory infiltration into gastric mucosa.

BACKGROUND/AIMS: CJ-20001 is a phytopharmaceutical agent and currently being investigated in a Phase II trial for the treatment of acute and chronic gastritis patients in Korea. In this study we addressed the protective effects of CJ-20001 against water immersion restraint stress (WIRS)-induced gastric injury in rats and studied the underlying mechanisms. METHODOLOGY: To evaluate the protective effect of CJ-20001 on stress-induced gastric lesions, rats were exposed to water immersion restraint stress. Inflammatory infiltration into gastric mucosa was examined by immunohistochemistry and in vitro invasion assay. Expression of proinflammatory cytokines was detected with reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Pretreatment with CJ-20001 dose-dependently attenuated the WIRS-induced gastric lesions as demonstrated by gross pathology and histology. WIRS increased infiltration of mast cells and macrophages into the gastric mucosa and submucosal layer, whereas the inflammatory infiltration was markedly inhibited by CJ-20001 administration. An in vitro cell invasion assay showed that treatment with CJ-20001 decreased the migration of macrophages. CJ-20001 suppressed the expression of proinflammatory cytokines, IL-18, IP-10 and GRO/KC, in lipopolysaccharides (LPS)-treated macrophages. CONCLUSIONS: These data suggest that novel phytopharmaceutical agent CJ-20001 has the potent anti-inflammatory properties through inhibition of inflammatory infiltration in psycho-physiological stress-induced gastric injury.

Depolymerization study of sodium hyaluronate by flow field-flow fractionation/multiangle light scattering.

Thermal depolymerization of ultrahigh-molecular-weight (UHMW) sodium hyaluronate (NaHA) was studied systematically by using frit-inlet asymmetrical flow field-flow fractionation/multiangle light scattering/differential refractive index (FI-AFlFFF/MALS/DRI). FI-AFlFFF was utilized for the size separation of NaHA samples which had been thermally degraded for varied treatment times, followed by light-scattering detection to determine MW and structural information of degraded NaHA products. Analysis of NaHA products showed time-dependent depolymerization of raw molecules into smaller-MW components, as well as unfolding of compact structures of UHMW NaHA. To determine whether the observed decrease in MW of sodium hyaluronate originated from the chain degradation of UHMW molecules or from dissociation of entangled complex particles that may have been formed by intermolecular association, narrow size fractions (1 x 10(7)-6 x 10(7) and >6 x 10(7) MW) of NaHA molecules were collected during FlFFF separation and followed by thermal treatment. Subsequent FI-AFlFFF/MALS analysis of collected fractions after thermal treatment suggested that the ultrahigh-MW region (>10(7) Da) of NaHA is likely to result from supermolecular structures formed by aggregation of large molecules.

Flow field-flow fractionation/multiangle light scattering of sodium hyaluronate from various degradation processes.

Sodium hyaluronate (NaHA) is an ultrahigh molecular weight polysaccharide that is found in body tissues, synovial fluid, the vitreous humor, and the umbilical cord, and the size characterization of NaHA is important in pharmaceutical applications. On-line field-flow fractionation/multiangle light scattering/differential refractive index (FlFFF/MALS/DRI) has been applied for the study of degradation efficiency of sodium hyaluronate (NaHA). A NaHA raw sample was degraded by different chemical or physical methods and the degraded NaHA samples were separated using field-programming FlFFF, in which separation is achieved by differences in diffusion coefficients or hydrodynamic diameters. Separation was followed by serial detection using MALS and DRI. Molecular weight distribution (MWD) and information relating to the radius of gyration of the NaHA samples were examined for the raw and degraded NaHA samples. Samples studied include: two different products of ultrasonic degradation, two products of alkaline degradation, and four different products of enzymatic degradation. While alkaline degradation showed a moderate degradation compared to ultrasonic and enzymatic methods in reducing average MW, the latter two degradation methods showed significant changes in average molecular weight and in conformation of NaHA.

Molecular weight and structure characterization of sodium hyaluronate and its gamma radiation degradation products by flow field-flow fractionation and on-line multiangle light scattering.

A combined flow field-flow fractionation (FlFFF)/multiangle light scattering (MALS)/differential refractive index (DRI) detection method has been utilized for the size fractionation and characterization of ultrahigh molecular weight (MW) sodium hyaluronate (NaHA) samples. Separation of broad MW NaHA polymers was carried out by a frit inlet asymmetrical FlFFF channel employed with a linear field programming method followed by the on-line monitoring of light scattering at multiple angles for the calculation of MW and for the study of the conformation of NaHA samples. NaHA samples examined were: (1) two different viscosity fractions of NaHA obtained by a refinement process and (2) NaHA products of gamma radiation degradation. While the NaHA samples of two different viscosity fractions exhibited clearly different MW distributions and similar conformation, the radiation degraded NaHA samples showed a clear difference in both MW distribution and polymer structure.

Effect of dissolution temperature on the structures of sodium hyaluronate by flow field-flow fractionation/multiangle light scattering.

Molecular weight distribution (MWD) and structural deformation of ultrahigh molecular weight (MW) sodium hylaluronate (10(5)-10(8) g/mol) were studied under different sample dissolution temperature conditions, using on-line flow field-flow fractionation (FlFFF) and multiangle light scattering (MALS). Sodium hyaluronate (NaHA) materials from sarcoma fluid have been studied by dissolving them in water at three different temperature conditions (5 degrees C, 50 degrees C, and 90 degrees C). Frit inlet asymmetrical flow field-flow fractionation (FI-AFlFFF), with field programming, was utilized for the separation of NaHA by MW, and on-line observation of light scattering of fractionated NaHA by MALS was performed in order to determine the MWD and molecular conformation. In these experiments, NaHA molecules exhibited an extended structure from a formerly rather compact geometry when the dissolving temperature was raised to 90 degrees C. This study also showed a clear difference in the MWD of NaHA when a preliminary filtration process was applied.