Tuning Optoelectrical Properties of ZnO Nanorods with Excitonic Defects via Submerged Illumination.

When applied in optoelectronic devices, a ZnO semiconductor dominantly absorbs or emits ultraviolet light because of its direct electron transition through a wide energy bandgap. On the contrary, crystal defects and nanostructure morphology are the chief key factors for indirect, interband transitions of ZnO optoelectronic devices in the visible light range. By ultraviolet illumination in ultrapure water, we demonstrate here a conceptually unique approach to tune the shape of ZnO nanorods from tapered to capped-end via apical surface morphology control. We show that oxygen vacancy point defects activated by excitonic effects near the tip-edge of a nanorod serve as an optoelectrical hotspot for the light-driven formation and tunability of the optoelectrical properties. A double increase of electron energy absorption on near band edge energy of ZnO was observed near the tip-edge of the tapered nanorod. The optoelectrical hotspot explanation rivals that of conventional electrostatics, impurity control, and alkaline pH control-associated mechanisms. Thus, it highlights a new perspective to understanding light-driven nanorod formation in pure neutral water.

Maternal Exposure to Pyrethroid Insecticides during Pregnancy and Infant Development at 18 Months of Age.

The possible association between maternal exposure to pyrethroid insecticides (PYRs) during pregnancy and infant development was explored. Levels of exposure to PYRs was assessed by metabolite (3-phenoybenzoic acid, 3-PBA) concentration in maternal spot urine sampled in the first trimester of index pregnancy, and infant development was assessed at 18 months of age using the Kinder Infants Development Scale (KIDS), which is based on a questionnaire to the caretaker. The relationship between KIDS score and maternal urinary 3-PBA levels was examined by a stepwise multiple regression analysis using biological attributes of the mother and infant, breast feeding, and nursing environment as covariates. The analysis extracted 3-PBA and the nursing environment as significant to explain the KIDS score at 18 months of age with positive partial regression coefficients. Inclusion of fish consumption frequency of the mother during pregnancy as an independent variable resulted in the selection of fish consumption as significant, while the two variables were marginally insignificant but still with a positive coefficient with the KIDS score. The result suggested a positive effect of maternal PYR exposure on infant development, the reason for which is not clear, but an unknown confounding factor is suspected.

A pathway of nanocrystallite fabrication by photo-assisted growth in pure water.

We report a new production pathway for a variety of metal oxide nanocrystallites via submerged illumination in water: submerged photosynthesis of crystallites (SPSC). Similar to the growth of green plants by photosynthesis, nanocrystallites shaped as nanoflowers and nanorods are hereby shown to grow at the protruded surfaces via illumination in pure, neutral water. The process is photocatalytic, accompanied with hydroxyl radical generation via water splitting; hydrogen gas is generated in some cases, which indicates potential for application in green technologies. Together with the aid of ab initio calculation, it turns out that the nanobumped surface, as well as aqueous ambience and illumination are essential for the SPSC method. Therefore, SPSC is a surfactant-free, low-temperature technique for metal oxide nanocrystallites fabrication.

The irradiation effect of a simultaneous laser and electron dual-beam on void formation.

Randomly distributed lattice point defects such as supersaturated vacancies (SVs) and Frenkel-pairs (FPs, an interstitial and a vacancy) can be simultaneously introduced into the crystal by energetic beam irradiation in outer space and/or nuclear reactors, but their behavior has not been fully understood. Using a high-voltage electron microscope equipped with a laser (laser-HVEM), we show the striking effects of simultaneous laser-electron (photon-electron) dual-beam irradiation on void formation. Our results reveal that during laser-electron sequential irradiation, pre-laser irradiation enhanced void nucleation and subsequent electron irradiation enhanced void growth. However, the laser-electron dual-beam irradiation was analyzed to depress void swelling remarkably because the recombination of SVs and interstitials was enhanced. The results provide insight into the mechanism underlying the dual-beam radiation-induced depression of void swelling in solids.

Fabrication of a Au/Si nanocomposite structure by nanosecond pulsed laser irradiation.

A gold/silicon nanocomposite structure (NCS) was formed on a Si(100) surface by nanosecond pulsed laser irradiation. The Au/Si NCS contained both Au nanoparticles (NPs) and Au-Si alloy layers. We report that the use of laser irradiation to form Au NPs comprises two competing processes: a top-down effect involving decomposition into smaller NPs and a bottom-up effect involving self-assembly or self-organization into larger NPs. The formation of the periodic structure involved self-organization, i.e., the bottom-up effect, and was observed in situ using a pulsed-laser-equipped high-voltage electron microscope. The NCS formed by laser irradiation can be controlled by adjusting the laser energy density and the number of laser pulses.

Synthesis and properties of oligonucleotides containing silylated pyrene derivatives.

Preparation and properties of the novel fluorescently labelled oligonucleotides, containing the silylated pyrene derivatives are reported. The silylated pyrene derivatives were introduced into both 5'-terminus and C-5 position of the deoxyuridine derivatives. The fluorescent spectra indicated the possibility of the discrimination of the duplex formation by the simple denaturation.

Genetic linkages between circadian clock-associated components and phytochrome-dependent red light signal transduction in Arabidopsis thaliana.

The current best candidates for Arabidopsis thaliana clock components are CCA1 (CIRCADIAN CLOCK-ASSOCIATED 1) and its homolog LHY (LATE ELONGATED HYPOCOTYL). In addition, five members of a small family, PSEUDO-RESPONSE REGULATORS (including PRR1, PRR3, PRR5, PRR7 and PRR9), are believed to be another type of clock component. The originally described member of PRRs is TOC1 (or PRR1) (TIMING OF CAB EXPRESSION 1). Interestingly, seedlings of A. thaliana carrying a certain lesion (i.e. loss-of-function or misexpression) of a given clock-associated gene commonly display a characteristic phenotype of light response during early photomorphogenesis. For instance, cca1 lhy double mutant seedlings show a shorter hypocotyl length than the wild type under a given fluence rate of red light (i.e. hypersensitivity to red light). In contrast, both toc1 single and prr7 prr5 double mutant seedlings with longer hypocotyls are hyposensitive under the same conditions. These phenotypes are indicative of linkage between the circadian clock and red light signal transduction mechanisms. Here this issue was addressed by conducting combinatorial genetic and epistasis analyses with a large number of mutants and transgenic lines carrying lesions in clock-associated genes, including a cca1 lhy toc1 triple mutant and a cca1 lhy prr7 prr5 quadruple mutant. Taking these results together, we propose a genetic model for clock-associated red light signaling, in which CCA1 and LHY function upstream of TOC1 (PRR1) in a negative manner, in turn, TOC1 (PRR1) serves as a positive regulator. PRR7 and PRR5 also act as positive regulators, but independently from TOC1 (PRR1). It is further suggested that these signaling pathways are coordinately integrated into the phytochrome-mediated red light signal transduction pathway, in which PIF3 (PHYTOCHROME-INTERACTING FACTOR 3) functions as a negative regulator immediately downstream of phyB.

Characterization of a set of phytochrome-interacting factor-like bHLH proteins in Oryza sativa.

The model dicotyledon Arabidopsis thaliana has a characteristic small sub-family of phytochrome-interacting bHLH (basic Helix-Loop-Helix) factors, which are collectively designated the PIL (or PIF) (PHYTOCHROME INTERACTING FACTOR-LIKE) family proteins. In this study, we identified and characterized a set of highly homologous members (designated OsPIL11 to OsPIL16) in the model monocotyledon rice (Oryza sativa). Some of them (OsPIL11, OsPIL12, and OsPIL13) showed the ability to interact with the putative OsPRR1 (PSEUDO-RESPONSE REGULATOR 1) clock component, as far as the results of yeast two-hybrid assays were concerned. It was found that the expression of OsPIL13 is under the control of circadian rhythms (clock), while the expression of OsPIL15 is negatively regulated by light upon the onset to light exposure of etiolated seedlings. When the rice genes (OsPIL11 to OsPIL15) were over-expressed in A. thaliana, the resulting transgenic seedlings displayed anomalous morphologies with very long hypocotyls during early photomorphogenesis. These results suggest the view that the identified OsPILs are functional counterparts (or orthologs) of AtPILs, which are known to play important roles in red light-mediated (phyA and/or phyB-dependent) signal transduction pathways at immediate positions downstream of the photoreceptor in A. thaliana.

Mutants of circadian-associated PRR genes display a novel and visible phenotype as to light responses during de-etiolation of Arabidopsis thaliana seedlings.

In Arabidopsis thaliana, it is currently accepted that certain mutants with lesions in clock-associated genes commonly display hallmarked phenotypes with regard to three characteristic biological events: (i) altered rhythmic expression of circadian-controlled genes, (ii) changes in flowering time, and (iii) altered sensitivity to red light in elongation of hypocotyls. During the course of examination of the clock-associated mutants of PSEUDO-RESPONSE REGULATORS, PRRs, including TOC1 (PRR1), we found that they commonly show another visible phenotype of anomalous greening responses upon the onset to light exposure of etiolated seedlings. These findings are indicative of a novel link between circadian rhythms and chloroplast development.

Characterization of circadian-associated pseudo-response regulators: II. The function of PRR5 and its molecular dissection in Arabidopsis thaliana.

Together with PRR1/TOC1, PRR5 belongs to the small family of Pseudo-Response Regulators (PRRs), which function as clock components of Arabidopsis thaliana. We employed a set of transgenic lines, each of which was designed to misexpress a truncated form of the PRR5 molecule, together with the original transgenic line (named PRR5-ox) that misexpresses the entire PRR5 polypeptide. The results of genetic analysis suggested that PRR5-ox seedlings showed a phenotype of hypersensitivity to red light during early photomorphogenesis in a manner dependent on red light photoreceptors (PhyA and PhyB), but independent of PRR1/TOC1. The set of newly constructed transgenic lines (named PRR5-N-ox and PRR5-C-ox) were also characterized in terms of circadian-associated phenotypes. The results suggest that the N-terminal pseudo-receiver domain of the PRR5 molecule seems to be dispensable for the misexpressed PRR5 molecule to bring about the phenotype of red light sensitivity. However, PRR5-N-ox plants, misexpressing only the pseudo-receiver domain, showed a phenotype of long period of free-running circadian rhythms of certain clock-controlled genes. Considering these and other results, we discuss the structure and function of PRR5 in the context of current views of the circadian clock in higher plants.

[Mental health status and effects on daily life of patients of a large outbreak of Legionnaires Disease].

OBJECTIVES: The aim of this study was to survey mental health status among patients of a large outbreak of Legionnaires Disease (LD) occurring at a public bath in Hyuga City, Miyazaki Prefecture, from June through July, 2002. It also aimed to provide a basis for establishing a mental health care support system for persons suffering from ill health. METHODS: Some 295 patients were reported by medical institutions to public health centers as being infected with LD or having suspected infection after using a hot springs bath, where hygiene was assumed to be maintained by regular water circulation, from 6/20 through 7/23, 2002 in Hyuga City, Miyazaki Prefecture. A total of 153 subjects consented to interviews after being informed of the objectives. They were visited and interviewed with a questionnaire from 10/12 through 12/5, 2002. Questions about mental health were written to identify "feeling stressed", based on diagnostic criteria for Post Traumatic Stress Disorder (PTSD) as noted in the DSM-IV. The Japanese version of the General Health Questionnaire (GHQ28) was used to identify high risk subjects for mental disorder, as well as the following four symptoms: "somatic symptoms", "anxiety and insomnia", "social dysfunction", and "severe depression". Factors associated with these were assessed with regard to knowledge and/or information about LD and its effects on daily life. RESULTS: Regarding mental health, 27 (17.6%) were "feeling stressed". High risk patients for mental disorder numbered 39 (25.5%) according to the GHQ28. Patients with "somatic symptoms" numbered 44 (28.8%), those with "anxiety and insomnia" 21 (13.7%), those with "social dysfunction" 18 (11.8%) and with "severe depression" 5 (3.3%). Among the effects on daily life, "changes of human relationships" was related with "feeling stressed" in those suspected of LD infections (P = 0.022). High risk was related to "economic support" (P = 0.009) in LD, and also to "cause and survey" (P = 0.035) in those cases suspected of LD. CONCLUSIONS: At 3 to 4 months after the outbreak, the patients still exhibited mental health problems. Therefore we should provide health and social support that deals with the factors identified on a longer-term or continuous basis.

Circadian-controlled basic/helix-loop-helix factor, PIL6, implicated in light-signal transduction in Arabidopsis thaliana.

PHYTOCHROME-INTERACTING FACTOR-LIKE 6 (PIL6) is a member of the large family of basic/helix-loop-helix (bHLH) factors in Arabidopsis thaliana. This circadian-controlled transcription factor was previously suggested to interact with the clock component, TIMING OF CAB EXPRESSION 1 (TOC1). In this study, we isolated a loss-of-function mutant of PIL6, together with a transgenic line aberrantly expressing PIL6 in a manner independent of circadian rhythm. These mutant plants were simultaneously examined with special reference to circadian rhythm and light-signal transduction. The results suggested that PIL6 appears to be not directly involved in the clock function per se. However, the loss-of-function mutant (pil6-1) showed a remarkable phenotype in that it is hypersensitive to red light in seedling de-etiolation. This phenotype was similar to that observed for transgenic lines overexpressing TOC1 (or APRR1). Conversely, transgenic plants overexpressing PIL6 (PIL6-ox) are hyposensitive to red light under the same conditions. This phenotype was very similar to that observed for phyB mutants. The developmental morphologies of PIL6-ox, including the phenotype of early flowering, were also similar to those of phyB mutants. We propose that PIL6 acts as a negative regulator for a red light-mediated morphogenic response (e.g., elongation of hypocotyls in de-etiolation). Taken together, PIL6 might function at an interface between the circadian clock and red light-signal transduction pathways.