Transport spectroscopy of symmetry-broken insulating states in bilayer graphene

Bilayer graphene is an attractive platform for studying new two-dimensional electron physics, because its flat energy bands are sensitive to out-of-plane electric fields and these bands magnify electron-electron interaction effects. Theory predicts a variety of interesting broken symmetry states when the electron density is at the carrier neutrality point, and some of these states are characterized by spontaneous mass gaps, which lead to insulating behaviour. These proposed gaps are analogous to the masses generated by broken symmetries in particle physics, and they give rise to large Berry phase effects accompanied by spontaneous quantum Hall effects. Although recent experiments have provided evidence for strong electronic correlations near the charge neutrality point, the presence of gaps remains controversial. Here, we report transport measurements in ultraclean double-gated bilayer graphene and use source-drain bias as a spectroscopic tool to resolve a gap of ∼2 meV at the charge neutrality point. The gap can be closed by a perpendicular electric field of strength ∼15 mV nm(-1), but it increases monotonically with magnetic field, with an apparent particle-hole asymmetry above the gap. These data represent the first spectroscopic mapping of the ground states in bilayer graphene in the presence of both electric and magnetic fields.

First Report of Rice stripe virus of Proso Millet in Korea

Rice stripe virus (RSV; genus Tenuivirus) is a serious threat to rice production in Korea (2). In 1965, a disease outbreak was observed on rice in South Korea, with plants showing yellow stripe symptoms (2). Reoccurrence of RSV in rice was observed again in 1980 in Gyeonggi and Chungcheong. In 2001, RSV was estimated to be infecting approximately 4,663 ha of rice in the provinces of Gyeonggi and Gangwha and approximately 5,000 ha of riceland in the provinces of Buan and, Seocheon (3). Proso millet (Panicum miliaceum L.) is grown as a cereal grain crop and used mainly for human food in South Korea (1). In June 2009, proso millet plants that displayed yellow stripe symptoms were collected at Sinjeon-Myeon, Gangjin-Gun, and Jeollanam-do provinces, where an outbreak of RSV in rice was reported. Diseased plants tested positive to RSV with an ELISA Kit (KisanBio, Seoul, Korea). Total RNA was extracted from leaf tissue with an RNeasy Plant Mini Kit (Qiagen Inc., Valencia, CA). RSV coat protein specific-primers were produced (5' TGTGGAACATAGTCCCACAGTAAGT 3'(upstream), 5' CTAAGCCGCAACCATTCCTCCAGT 3'(downstream). Reverse transcription-PCR confirmed the presence of a 494-bp product as predicted for the presence of RSV. The coat protein of RSV isolates collected from proso millet, rice, and foxtail millet in the same area was also sequenced. Results confirmed that phylogenetic relationships were of high homology: 98.9% between RSV isolates from rice and foxtail millet, 99.2% between isolates from rice (GenBank Accession No. JN245626) and proso millet (GenBank Accession No. JN245627); 99.6% between rice and foxtail millet (GenBank Accession No. JN245628); and 99.6% between foxtail millet and proso millet. In addition, sequence comparisons showed 96 to 99% identity with known RSV sequences available in GenBank (Accession No. X53563) (4). To our knowledge, this is the first report of RSV of proso millet in South Korea. The finding of this disease confirms further spread of the virus within the northern part of South Korea and the need for research to develop more effective management options to reduce the impact of RSV in proso millet. References: (1) Y. Y. Choi et al. Biosci. Biotechnol. Biochem. 69:31, 2005. (2) B. C. Lee et al. Res. Plant Dis. 10:30, 2004. (3) B. C. Lee et al. Res. Plant Dis. 14:210, 2008. (4) Y. Zhu. J. Gen. Virol. 72:763, 1991.

In-house information about and contact with self-help groups in breast cancer patients: associated with patient and hospital characteristics?

The number of breast cancer patients who are informed about and have contact with patient self-help groups (SHGs) during their hospital stay varies across hospitals. The aim of this study is to investigate which patient and hospital characteristics contribute to these differences. Multilevel regression analysis was applied, using data on hospital characteristics and data from a patient survey, which catalogued the disease and socio-demographic characteristics of newly diagnosed breast cancer patients, and recorded if they were informed about and had contact with SHGs during their hospital stay. Data from 2639 patients from 82 hospitals were analysed. The odds of being informed about SHGs were significantly lower if patients were treated at a teaching hospital. Patients aged 40 to 59 years significantly more often reported that they were informed about SHGs than patients aged 60 to 69 years. Patients with the highest education certificates significantly more often reported that they both were informed about and have had contact with SHGs. These results suggest that in teaching hospitals, information provided to patients about SHGs is reduced. Furthermore, patients are differentially given information about SHGs and have different levels of contact with SHGs, based on their age and education.

Detection of genetically modified microorganisms in soil using the most-probable-number method with multiplex PCR and DNA dot blot

The principal objective of this study was to detect genetically modified microorganisms (GMMs) that might be accidentally released into the environment from laboratories. Two methods [plate counting and most-probable-number (MPN)] coupled with either multiplex PCR or DNA dot blots were compared using genetically modified Escherichia coli, Pseudomonas putida, and Acinetobacter oleivorans harboring an antibiotic-resistance gene with additional gfp and lacZ genes as markers. Alignments of sequences collected from databases using the Perl scripting language (Perl API) and from denaturing gradient gel electrophoresis analysis revealed that the gfp, lacZ and antibiotic-resistance genes (kanamycin, tetracycline, and ampicillin) in GMMs differed from the counterpart genes in many sequenced genomes and in soil DNA. Thus, specific multiplex PCR primer sets for detection of plasmid-based gfp and lacZ antibiotic-resistance genes could be generated. In the plate counting method, many antibiotic-resistant bacteria from a soil microcosm grew as colonies on antibiotic-containing agar plates. The multiplex PCR verification of randomly selected antibiotic-resistant colonies with specific primers proved ineffective. The MPN-multiplex PCR method and antibiotic-resistant phenotype could be successfully used to detect GMMs, although this method is quite laborious. The MPN-DNA dot blot method screened more cells at a time in a microtiter plate containing the corresponding antibiotics, and was shown to be a more efficient method for the detection of GMMs in soil using specific probes in terms of labor and accuracy.

Thermoelectric properties of Ca(1-x-y)Dy(x)CeyMnO3 for power generation

The sintered Ca(1-x-y)Dy(x)CeyMnO3 bodies were a single phase with a perovskite structure without any impurity phases. The calculated crystallite sizes of the Ca(1-x-y)Dy(x)CeyMnO3 were in the range of 43.3 to 63.3 nm. The composition significantly affected their microstructural and thermoelectric characteristics. The doped Dy led to both an increase in the electrical conductivity as well as the absolute value of the Seebeck coefficient, resulting in an enhanced power factor. The highest power factor (5.1 x 10(-4) Wm(-1) K(-2)) was obtained for Ca(0.8)Dy(0.2)MnO3 at 800 degrees C. In this study, we systematically discussed the thermoelectric properties of the Ca(1-x-y)Dy(x)CeyMnO3, with respect to the substitution of Dy and/or Ce for Ca.

Change in gene abundance in the nitrogen biogeochemical cycle with temperature and nitrogen addition in Antarctic soils

The microbial community (bacterial, archaeal, and fungi) and eight genes involved in the nitrogen biogeochemical cycle (nifH, nitrogen fixation; bacterial and archaeal amoA, ammonia oxidation; narG, nitrate reduction; nirS, nirK, nitrite reduction; norB, nitric oxide reduction; and nosZ, nitrous oxide reduction) were quantitatively assessed in this study, via real-time PCR with DNA extracted from three Antarctic soils. Interestingly, AOB amoA was found to be more abundant than AOA amoA in Antarctic soils. The results of microcosm studies revealed that the fungal and archaeal communities were diminished in response to warming temperatures (10 °C) and that the archaeal community was less sensitive to nitrogen addition, which suggests that those two communities are well-adapted to colder temperatures. AOA amoA and norB genes were reduced with warming temperatures. The abundance of only the nifH and nirK genes increased with both warming and the addition of nitrogen. NirS-type denitrifying bacteria outnumbered NirK-type denitrifiers regardless of the treatment used. Interestingly, dramatic increases in both NirS and NirK-types denitrifiers were observed with nitrogen addition. NirK types increase with warming, but NirS-type denitrifiers tend to be less sensitive to warming. Our findings indicated that the Antarctic microbial nitrogen cycle could be dramatically altered by temperature and nitrogen, and that warming may be detrimental to the ammonia-oxidizing archaeal community. To the best of our knowledge, this is the first report to investigate genes associated with each process of the nitrogen biogeochemical cycle in an Antarctic terrestrial soil environment.

Sciatic nerve injury induces functional pro-nociceptive chemokine receptors in bladder-associated primary afferent neurons in the rat

Visceral sensory afferents during disease or following injury often produce vague, diffuse body sensations, and pain referred to somatic targets. Alternatively, injury due to trauma or disease of somatic nerve targets can also lead to referred pain in visceral targets via a somatovisceral reflex. Both phenomenons are thought to be due to convergence of visceral and somatic afferents within the spinal cord. To investigate a potential peripheral influence for referred pain in visceral targets following somatic nerve injury, we examined whether a sciatic nerve injury known to produce hindpaw tactile hyperalgesia alters the frequency of micturition and the sensitivity of bladder-associated sensory neurons to pro-nociceptive chemokines. Adult female Sprague-Dawley rats received injections of cholera toxin B subunit conjugated to 555 into urinary bladder wall to retrogradely label visceral primary afferent neurons. After 7 days, the right sciatic nerve of these animals was subjected to a lysophosphatidylcholine (LPC)-induced focal demyelination injury. Pre- and post-injury tactile sensitivity in the hind paw and micturition frequency were assayed. Animals were allowed to survive for 14-28 days. Lumbosacral and lumbar dorsal root ganglia (DRG) ipsilateral to the nerve injury were acutely dissociated from sham and nerve injured animals. Bladder wall-associated sensory neurons identified via the retrograde marker were assayed for fluxes in intracellular calcium following administration of pro-nociceptive chemokines. The assayed chemokines included monocyte chemoattractant protein-1 (MCP1/CCL2) and stromal cell derived factor-1 alpha (SDF1/CXCL12). LPC nerve injured animals exhibited tactile hyperalgesia and increased micturition frequency for at least 28 days. Focal demyelination of the sciatic nerve also increased the number of injured L₄L₅ and non-injured L₆-S₂ bladder-associated sensory neurons that responded to MCP1 and SDF1 when compared with sensory neurons derived from uninjured naïve and sham-injured control animals. Taken together, these data suggest that some visceral hypersensitivity states may have a somatic origin. More importantly, nociceptive somatovisceral sensation may be mediated by upregulation of chemokine signaling in visceral sensory neurons.

Physiological and metabolic responses for hexadecane degradation in Acinetobacter oleivorans DR1

The hexadecane degradation of Acinetobacter oleivorans DR1 was evaluated with changes in temperature and ionic salt contents. Hexadecane degradation of strain DR1 was reduced markedly by the presence of sodium chloride (but not potassium chloride). High temperature (37°C) was also shown to inhibit the motility, biofilm formation, and hexadecane biodegradation. The biofilm formation of strain DR1 on the oil-water interface might prove to be a critical physiological feature for the degradation of hexadecane. The positive relationship between biofilm formation and hexadecane degradation could be observed at 30° C, but not at low temperatures (25°C). Alterations in cell hydrophobicity and EPS production by temperature and salts were not correlated with biofilm formation and hexadecane degradation. Our proteomic analyses have demonstrated that metabolic changes through the glyoxylate pathway are important for efficient degradation of hexadecane. Proteins involved in fatty acid metabolism, gluconeogenesis, and oxidative stress defense proteins appear to be highly expressed during biodegradation of hexadecane. These results suggested that biofilm formation and oxidative stress defense are important physiological responses for hexadecane degradation along with metabolic switch to glyoxylate pathway in strain DR1.