Perfect Bi4Ti3O12 Single‐Crystal Films via Flux‐Mediated Epitaxy

Excellent crystallinity of material films and atomic control of their surface/interface, sufficient for the realization of their optimal physical properties, are technological premises for modern functional‐device applications. Bi₄Ti₃O₁₂ and related compounds attract much interest as highly insulating, ferroelectric materials for use in ferroelectric random‐access memories. However, it has been difficult thus far for Bi₄Ti₃O₁₂ films to satisfy such requirements when formed using vapor‐phase epitaxy, owing to the high volatility of Bi in a vacuum. Here, we demonstrate that flux‐mediated epitaxy is one of the most promising and widely applicable concepts to overcome this inevitable problem. The key point of this process is the appropriate selection of a multi‐component flux system. A combinatorial approach has led to the successful discovery of the novel flux composition of Bi–Cu–O for Bi₄Ti₃O₁₂ single‐crystal film growth. The perfect single‐crystal nature of the stoichiometric Bi₄Ti₃O₁₂ film formed has been verified through its giant grain size and electric properties, equivalent to those of bulk single crystals. This demonstration has broad implications, opening up the possibility of preparing stoichiometric single‐crystal oxide films via vapor‐phase epitaxy, even if volatile constituents are required.     

Increased serum vascular endothelial growth factor levels and intrathyroidal vascular area in patients with Graves' disease and Hashimoto's thyroiditis

Vascular endothelial growth factor (VEGF) is one of the angiogenic factors. We examined both thyroid volume and intrathyroidal vascular area by color flow Doppler ultrasonography in patients with Graves' disease (GD), Hashimoto's thyroiditis (HT), and subacute thyroiditis. The serum concentrations of thyroid hormones, TSH, TSH receptor antibodies, and VEGF were also examined. There was a significant increase in serum VEGF levels in patients with untreated GD and goitrous HT compared with those in healthy subjects. The serum VEGF levels in untreated patients with subacute thyroiditis were significantly higher than those in patients with untreated GD or HT. There was a significant correlation between serum VEGF levels and the ratio of intrathyroidal vascular area and thyroid area in untreated patients with GD who had a goiter larger than or equal to 40 cm3. There was also a significant correlation between serum VEGF and TSH levels in patients with HT who were hypothyroid and had a goiter. Serum VEGF levels decreased significantly in these patients after treatment; this was accompanied by a significant decrease in intrathyroidal vascular area and thyroid volume. Our study demonstrates that VEGF appears to play an important role in intrathyroidal angiogenesis in patients with GD and goitrous HT.     

T cell receptor restriction of diabetogenic autoimmune NOD T cells

Restricted use of T cell receptor (TCR) gene segments is characteristic of several induced autoimmune disease models. TCR sequences have previously been unavailable for pathogenic T cells which react with a defined autoantigen in a spontaneous autoimmune disease. The majority of T cell clones, derived from islets of NOD mice which spontaneously develop type I diabetes, react with insulin peptide B-(9-23). We have sequenced the alpha and beta chains of TCRs from these B-(9-23)-reactive T cell clones. No TCR beta chain restriction was found. In contrast, the clones (10 of 13) used V alpha13 coupled with one of two homologous J alpha segments (J alpha45 or J alpha34 in 8 of 13 clones). Furthermore, 9 of 10 of the V alpha13 segments are a novel NOD sequence that we have tentatively termed V alpha13.3. This dramatic alpha chain restriction, similar to the beta chain restriction of other autoimmune models, provides a target for diagnostics and immunomodulatory therapy.     

Repeated temperature modulation epitaxy for p-type doping and light-emitting diode based on ZnO.

Since the successful demonstration of a blue light-emitting diode (LED), potential materials for making short-wavelength LEDs and diode lasers have been attracting increasing interest as the demands for display, illumination and information storage grow. Zinc oxide has substantial advantages including large exciton binding energy, as demonstrated by efficient excitonic lasing on optical excitation. Several groups have postulated the use of p-type ZnO doped with nitrogen, arsenic or phosphorus, and even p-n junctions. However, the choice of dopant and growth technique remains controversial and the reliability of p-type ZnO is still under debate. If ZnO is ever to produce long-lasting and robust devices, the quality of epitaxial layers has to be improved as has been the protocol in other compound semiconductors. Here we report high-quality undoped films with electron mobility exceeding that in the bulk. We have used a new technique to fabricate p-type ZnO reproducibly. Violet electroluminescence from homostructural p-i-n junctions is demonstrated at room-temperature.     

Molecular cloning and nucleotide sequence of an endo-1,5-alpha-L-arabinase gene from Bacillus subtilis

The nucleotide sequence of the gene encoding an endo-1,5-alpha-L-arabinase (protopectinase C) of Bacillus subtilis was determined by sequencing fragments amplified by the cassette-ligation-mediated PCR (CLM-PCR). The gene covering the start and stop codon was amplified by PCR with two specific primers, which were designed from the sequence data determined by CLM-PCR. An approximately 1.5-kb amplification product was cloned into the vector pUC119, forming a plasmid termed pPPC. An ORF that encodes the arabinase composed of 324 amino acids including a 33-amino-acid signal peptide was assigned. Comparison of the deduced amino acid sequence of the enzyme with that of an Aspergillus niger endoarabinase showed 37% identity in a 207-amino-acid overlap. The optimal nucleotide sequence for catabolite repression of B. subtilis was found upstream of the structural gene. In a culture of Escherichia coli DH5alpha cells harboring pPPC, no arabinase activity was detected, either intracellularly or extracellularly, suggesting that the B. subtilis promotor is not functional in this transformant. In B. subtilis IFO 3134 strain, production of protopectinase C was repressed by readily metabolizable carbohydrates. In contrast, productivity (total enzyme activity/bacterial growth) of the enzyme was increased about fourfold in the presence of 0.75 M potassium phosphate in the culture medium. The phosphate anion seemed to be involved in the stimulation of protopectinase C production in this stain.     

Lumboperitoneal shunting for pseudotumor cerebri

To clarify the appropriate role of lumboperitoneal (LP) shunting in the surgical management of pseudotumor cerebri (PTC), we retrospectively analyzed the clinical data from 30 patients who underwent this procedure. We found LP shunting to be an effective means of acutely lowering intracranial pressure. Symptoms of increased intracranial pressure improved in 82% of patients. Among 14 eyes with impaired visual acuity, 10 (71%) improved by at least two lines. Worsening of vision occurred in only one eye. Of 28 eyes with abnormal Goldmann perimetry, 18 (64%) improved and none worsened. The incidence of serious complications was low. The major drawback of LP shunting was the need for frequent revisions in a few patients. The reason for poor shunt tolerance in certain individuals is unclear. In PTC, LP shunting should be considered as the first surgical procedure for patients with severe visual loss at presentation or with intractable headache (with or without visual loss). After shunting it is important to identify patients who are shunt intolerant.     

Effectiveness of Some Natural Antimicrobial Compounds in Controlling Pathogen or Spoilage Bacteria in Lightly Fermented Chinese Cabbage

ABSTRACT: This study was designed to evaluate the bactericidal or bacteriostatic effect of chitosan, an allyl isothiocyanate (AIT) product, and nisin for the artificially inoculated pathogenic bacteria ( Escherichia coli , Salmonella Enteritidis, Staphylococcus aureus , and Listeria monocytogenes ) or natural microflora of fermented Chinese cabbage. Addition of 0.1% chitosan decreased the population of pathogens from 0.7 to 1.7 log colony-forming units (CFU)/g after 4 d of storage at 10 °C. The bactericidal activity of chitosan was found to be stronger than that of nisin (0.05 mg/g). Addition of 0.2% of the AIT product (containing AIT and hop extract) exhibited a bacteriostatic effect. However, a combination of AIT product and chitosan enhanced bactericidal efficacy against L. monocytogenes . The addition of chitosan or AIT product was observed to suppress the populations of mesophilic and coliform bacteria during storage at 10 °C for 4 d. Moreover, the use of chitosan or the AIT product did not change the sensory quality of the lightly fermented vegetable. Therefore, these results suggest that chitosan or the AIT product could be useful to improve the microbial safety and quality of lightly fermented vegetable.     

Improvement of Selectivity for Partial Hydrogenation of Benzene by Rare Earth Nitride Upon NH3 Treatment

For the liquid-phase partial hydrogenation of benzene at 483 K, the selectivity toward cyclohexene was greatly improved upon treating rare earth nitride with ammonia. For YbN obtained by thermal decomposition of Yb(NH₂)₂ at 1173 K, the selectivity of the NH₃-treated YbN was 75%, in contrast to nil for the untreated YbN.