Efficient Excitonic Photoluminescence in Direct and Indirect Band Gap Monolayer MoS2.

We discuss the photoluminescence (PL) of semiconducting transition metal dichalcogenides on the basis of experiments and a microscopic theory. The latter connects ab initio calculations of the single-particle states and Coulomb matrix elements with a many-body description of optical emission spectra. For monolayer MoS2, we study the PL efficiency at the excitonic A and B transitions in terms of carrier populations in the band structure and provide a quantitative comparison to an (In)GaAs quantum well-structure. Suppression and enhancement of PL under biaxial strain is quantified in terms of changes in the local extrema of the conduction and valence bands. The large exciton binding energy in MoS2 enables two distinctly different excitation methods: above-band gap excitation and quasi-resonant excitation of excitonic resonances below the single-particle band gap. The latter case creates a nonequilibrium distribution of carriers predominantly in the K-valleys, which leads to strong emission from the A-exciton transition and a visible B-peak even if the band gap is indirect. For above-band gap excitation, we predict a strongly reduced emission intensity at comparable carrier densities and the absence of B-exciton emission. The results agree well with PL measurements performed on monolayer MoS2 at excitation wavelengths of 405 nm (above) and 532 nm (below the band gap).

Development and characterization of mouse monoclonal antibodies reactive with chicken IL-1ß.

Interleukin-1ß proteins from chicken, duck, goose, turkey, and pigeon share 77 to 99% amino acid sequence similarity among themselves, and only 31 to 35% sequence similarity is shared between avian and mammalian IL-1ß. There have been no antibodies that specifically detect avian IL-1ß, and the current study was conducted to develop mouse monoclonal antibodies (mAb) against chicken IL-1ß (chIL-1ß) to further define its biochemical and immunological properties. In this study, 2 mouse mAb that are specific for chIL-1ß were produced and characterized. Both mAb identified a 66.0 kDa recombinant chIL-1ß protein expressed in Escherichia coli by Western blot analysis that corresponded to the expected molecular weight of a recombinant fusion protein containing the full-length 23.0 kDa chIL-1ß protein and a 43.0 kDa maltose binding protein tag. Immunohistochemical analysis identified cells producing endogenous chIL-1ß in the cecal tonsils, bursa of Fabricius, and spleen. Purified recombinant chIL-1ß dose-dependently stimulated the proliferation and nitric oxide production by thymocytes, and both activities were inhibited by co-incubation with the 2 chIL-1ß mAb described in this paper. These mAb will be important immune reagents for basic and applied poultry research of IL-1ß in poultry.

Effects of in ovo injection with selenium on immune and antioxidant responses during experimental necrotic enteritis in broiler chickens.

This study was conducted to investigate the effects of in ovo injection of Se on modulating the immune system and antioxidant responses in broiler chickens with experimental necrotic enteritis. Broiler eggs were injected at 18 d of embryo age with either 100 µL of PBS alone or sodium selenite (Na2SeO3) in PBS, providing 0 (SS0), 10 (SS10), or 20 (SS20) µg of Se/egg. At 14 d posthatch, PBS-treated and uninfected chickens were kept as the control group, whereas the remaining chickens were orally infected with 1.0 × 10(4) sporulated oocysts of Eimeria maxima (SS0, SS10, SS20). At 18 d posthatch, E. maxima-infected chickens were orally infected with 1.0 × 10(9) cfu of Clostridium perfringens. Infected control SS0 group showed significantly decreased BW compared with the uninfected control. However, SS20 group showed significantly increased BW compared with the infected control SS0 group, whereas the BW were similar among uninfected control and infected SS10 and SS20 groups. The SS10 group showed significantly lower intestinal lesions compared with the SS0 group, and oocyst production was decreased in both SS10 and SS20 groups. Serum malondialdehyde level and catalase activity were also decreased in both SS10 and SS20 groups, whereas the superoxide dismutase level was significantly lower in the SS10 group compared with the SS0 group. The SS20 group showed significantly higher levels of transcripts for IL-1ß and IL-6 in intestine, and SS10 and SS20 groups had higher levels of transcripts for IL-8 and inducible nitric oxide synthase expression and decreased glutathione peroxidase 7 mRNA levels compared with the SS0 group. The SS10 and SS20 groups also showed increased serum antibody levels to C. perfringens α-toxin and NetB toxin compared with the SS0 group. These collective results suggest that the injection of Se into the amniotic cavity of developing eggs may be beneficial for enhancing immune and antioxidant responses in the hatched chickens exposed to the necrotic enteritis-causing pathogens.

Terahertz near-field enhancement in narrow rectangular apertures on metal film.

We report huge field accumulations in rectangular aperture arrays on thin metal film by using shape resonance in THz frequency region. A huge far-field transmission enhancement is observed in samples of various widths ranging from 10 mum to 1.8 mum which correspond to only an order of lambda/100. Theoretical calculations based on vector diffraction theory indicates 230 times near-field enhancement in case of the 1.8 mum wide rectangular aperture. Transmission measurement through the single rectangular aperture shows that the shape resonance, not the periodicity, is mainly responsible for the transmission enhancement and the corresponding field enhancement.

The rapid growth of vertically aligned carbon nanotubes using laser heating.

Growth of densely packed vertically aligned carbon nanotubes (VA-CNTs) using laser-induced chemical vapor deposition with visible laser (lambda = 532 nm) irradiation at room temperature is reported. Using a multiple-catalyst layer (Fe/Al/Cr) on quartz as the substrate and an acetylene-hydrogen mixture as the precursor gas, VA-CNT pillars with 60 microm height and 4 microm diameter were grown at a high rate of around 1 microm s(-1) with good reproducibility. It is demonstrated that the fabrication of uniform pillar arrays of VA-CNTs can be achieved with a single irradiation for each pillar using LCVD with no annealing or preprocessing of the substrate. Here, laser fast heating is considered the primary mechanism facilitating the growth of VA-CNT pillars. Field emission characteristics of an array of VA-CNT pillars were then examined to investigate their potential application in vacuum electronic devices.

Frequencies of CYP3A5 genotypes and haplotypes in a Korean population.

BACKGROUND AND OBJECTIVE: CYP3A, the drug-metabolizing enzyme is an important factor in the pharmacokinetics of many drugs. Polymorphism of the CYP3A5 gene is known to influence the functionality of the CYP3A5 enzymes. The full extent of CYP3A5 genetic polymorphism was analysed in a Korean population. METHODS: Specific polymerase chain reaction-restriction fragment length polymorphism tests for CYP 3AP1 through CYP3A5*7 or direct sequencing were used to identify reported CYP3A5 variant alleles, using 194 unrelated samples. RESULTS AND DISCUSSION: The most frequent single nucleotide polymorphism (SNP) was 6986A>G (CYP3A5*3). The next most frequent SNP was 31611C>T. Haplotype analysis using detected SNPs revealed that the most frequent haplotype was *3A (frequency: 0.724), followed by *1E (frequency: 0.211), *3C (frequency: 0.034) and *1A (frequency: 0.023). We did not find CYP3AP1*3, CYP3A5*6, or *7 in this Korean sample. CONCLUSION: A large proportion of Koreans may have relatively low levels of metabolically active CYP3A5 protein and therefore may be at risk of high levels of drugs metabolized by this enzyme, after administration of conventional doses.

Nonassociation of interleukin-1 receptor antagonist genotypes with bone mineral density, bone turnover status, and estrogen responsiveness in Korean postmenopausal women.

Interleukin-1 receptor antagonist (IL-1ra), a natural inhibitor of interleukin-1 (IL-1), completely inhibits the stimulatory effects of IL-1 on bone resorption. Bioactivity of IL-1 increases in the estrogen-deficient state with an increased IL-1:IL-1ra ratio and decreases after estrogen replacement therapy with a decreased IL-1:IL-1ra ratio. An association was found between an 86 basepair variable number tandem-repeat (VNTR) polymorphism of the IL-1ra gene and an increased production of IL-1ra in a cultured monocyte system. The IL-1ra VNTR polymorphism, therefore, is an attractive candidate gene for osteoporosis susceptibility as well as hormone responsiveness after estrogen replacement. We examined the association of this VNTR polymorphism with bone mass, bone turnover, and the change of bone mineral density (BMD) after 1 year of hormone replacement therapy (HRT). The frequencies of the five alleles were as follows: A1, 90.8% (410 bp, four repeats); A2, 7.2% (240 bp, two repeats); A3, 1.6% (500 bp, five repeats); A4, 0.4% (326 bp, three repeats); and A5, 0% (595 bp, six repeats), in 714 healthy ethnically Korean postmenopausal women, aged 41-74 years (55.2 +/- 6.3 years mean +/- SD). Spine (L2-4) and femoral neck BMD were not significantly different among IL-1ra genotypes, and no significant genotypic differences were found in bone markers. There were no differences in genotypic proportions when we categorized the subjects into a high-loss group and a normal-loss group with regard to levels of bone marker. No significant genotypic differences were found in changes in lumbar and femoral neck BMD and those in bone markers before and after 1 year of HRT in 312 women. Our data suggest that these IL-1ra polymorphisms are not associated with BMD, bone turnover, or the change of BMD after 1 year of HRT in Korean women.

Delayed-type hypersensitivity reaction to piperacillin/tazobactam in a patient with an infected total knee replacement.

We describe a patient who developed a delayed-type hypersensitivity reaction to piperacillin/tazobactam in the cement beads and a spacer inserted at revision of total replacement of the left knee. We believe that this is the first report of such a problem. Our experience suggests that a delayed-type hypersensitivity reaction should be considered when a mixture of antibiotics such as piperacillin/tazobactam has been used in the bone cement, beads or spacer and the patient develops delayed symptoms of pain or painful paraesthesiae, fever, rash and abnormal laboratory findings in the absence of infection. The diagnosis was made when identical symptoms were induced by a provocation challenge test.

The complications of high tibial osteotomy: closing- versus opening-wedge methods.

We compared the incidence and severity of complications during and after closing- and opening-wedge high tibial osteotomy used for the treatment of varus arthritis of the knee, and identified the risk factors associated with the development of complications. In total, 104 patients underwent laterally based closing-wedge and 90 medial opening-wedge high tibial osteotomy between January 1993 and December 2006. The characteristics of each group were similar. All the patients were followed up for more than 12 months. We assessed the outcome using the Hospital for Special Surgery knee score, and recorded the complications. Age, gender, obesity (body mass index > 27.5 kg/m(2)), the type of osteotomy (closing versus opening) and the pre-operative mechanical axis were subjected to risk-factor analysis. The mean Hospital for Special Surgery score in the closing and opening groups improved from 73.4 (54 to 86) to 91.8 (81 to 100) and from 73.8 (56 to 88) to 93 (84 to 100), respectively. The incidence of complications overall and of major complications in both groups was not significantly different (p = 0.20 overall complication, p = 0.29 major complication). Logistic regression analysis adjusting for obesity and the pre-operative mechanical axis showed that obesity remained a significant independent risk factor (odds ratio = 3.23) of a major complication after high tibial osteotomy. Our results suggest that the opening-wedge high tibial osteotomy can be an alternative treatment option for young patients with medial compartment osteoarthritis and varus deformity.

The role of spinal and peripheral alpha1- and alpha2-adrenoceptors on bladder activity induced by bladder distension in anaesthetized rat.

OBJECTIVE: To elucidate the effects of alpha1- and alpha2-adrenoceptor antagonists on the micturition reflex induced by bladder distension in the anaesthetized rat at the peripheral and spinal level. Materials and methods Using continuous cystometry in 80 anaesthetized female Sprague-Dawley rats, changes in basal pressure (BaP), micturition pressure (MP), bladder capacity (BC), micturition volume (MV), interval of bladder contraction (frequency) and residual volume (RV) to the selective intra-arterial and intrathecal administration of drugs were monitored and analysed. RESULTS: The intra-arterial administration of phentolamine, prazosin, doxazosin and tamsulosin significantly decreased the MP; doxazosin increased MV, BC, RV and frequency. MP was inhibited more by intra-arterial doxazosin than by prazosin or tamsulosin. Intrathecal phentolamine increased BaP, BC, RV and decreased MP and MV; tamsulosin decreased frequency and increased BC. Clonidine markedly increased BaP and frequency, whereas MV and BC were significantly lower; yohimbine increased MV, BC and decreased RV. Intra-arterial yohimbine significantly increased MV. CONCLUSIONS: At the spinal level, the micturition reflex evoked by bladder distension was preferentially suppressed by phentolamine or yohimbine, suggesting the involvement of alpha2-adrenoceptors. In the periphery, alpha1-adrenoceptor blockers preferentially suppressed the reflex. We suggest that both alpha1- and alpha2-adrenoceptors play a role in the distension-evoked micturition reflex in the rat.

Tc-99m dimercaptosuccinic acid(DMSA) renal scintigraphy in patients with acute pyelonephritis.

OBJECTIVES: Recently, several authors reported that Tc-99m DMSA renal scan frequently showed cortical defects of the involved kidneys even in the patients with acute pyelonephritis who did not show abnormal findings in the ultrasonography and intravenous pyelography (IVP). METHODS: In order to evaluate the utilities of Tc-99m DMSA renal scan and the clinical meaning of cortical defects in the Tc-99m DMSA renal scan of the patients with acute pyelonephritis, ninety two patients with acute pyelonephritis, from March 1991 to February 1994 in Chungnam National University Hospital(CNUH), were included in this study. Patients were subdivided as Group A:Patients showing normal Tc-99m DMSA renal scan (n = 42) and Group B:Patients with definite cortical defects on the Tc-99m DMSA renal scan (n = 50). We compared clinical characteristics such as age and sex, recurrency, duration of fever, bacterial culture study, incidence of renal insufficiency and the results of renal ultrasonography and intravenous pyelography between the two groups. RESULTS: Fifty four percents of 92 patients with acute pyelonephritis showed a significantly longer febrile period after admission, higher positive rates on the urine and blood culture studies and higher incidence of renal insufficiency than those of the Group A patients. Sixty nine percents of Group B patients showed normal results in ultrasonography or IVP study. CONCLUSIONS: Tc-99m DMSA renal scan was a more sensitive imaging test than ultrasonography in kidneys and IVP to detect pyelonephritis lesions and may be useful to predict the patient group with a severe disease course. These patients may need more careful management and further studies to evaluate the possibility of complications.