[The vitamin D nutritional status in Chinese urban women of child-bearing age from 2010 to 2012]

Objective: To evaluate the vitamin D nutritional status in Chinese women of child-bearing age by analyzing serum 25-hydroxyvitamin D level in 2010-2012. Methods: Data were obtained from the China Nutrition and Health Survey in 2010-2012. Using cluster sampling and proportional stratified random sampling, 1 514 women of child-bearing age (18-44 years old) from 34 metropolis and 41 small and medium-sized cities were included in this study. Demographic information was collected by questionnaire and serum 25-hydroxyvitamin D concentration was determined by radioimmunoassay, in accordance with the 2010 Institute of Medicine of the National Academies standards. We compared differences in vitamin D levels, specifically serious deficiency, lack of deficiency, insufficiency, and excess. Results: The overall serum 25-hydroxyvitamin D level of Chinese urban women of child-bearing age (P(50) (P(25)-P(75))) was 20.1 (15.1-26.3) ng/ml; minorities had a significantly higher serum 25-hydroxyvitamin D level of 22.0 (15.9-27.5) ng/ml compared with women of Han nationality (19.8 (14.9-26.2) ng/ml) (χ(2)=7.02, P=0.008). The proportions of women with serious deficiency, lack of deficiency, insufficiency, and excess vitamin D were 11.6% (n=175), 37.9% (n=574), 35.1% (n=531), and 0.3% (n=5), respectively. Only 15.1% (n=229) of women of child-bearing age had normal vitamin D nutritional status. No significant differences in vitamin D nutritional status were observed according to age, body mass index, city, nationality, educational level, marital status, or household income per capita (P>0.05). Conclusion: Most Chinese urban women of child-bearing age have poor vitamin D levels and require vitamin D supplementation.

[Study on vitamin A nutritional status of Chinese urban elderly residents in 2010-2012]

Objective: To assess the vitamin A nutritional status of the Chinese urban elderly population by analyzing serum retinol level in 2010-2012. Methods: Data were collected from the Chinese National Nutrition and Health Survey in 2010-2012. Using the multi-stage stratified cluster sampling method, serum samples from elderly residents aged ≥60 years old were obtained from 34 metropolis and 41 middle-sized and small cities. Demographic data were collected using a questionnaire survey. The serum retinol concentration was determined by high-performance liquid chromatography. Vitamin A deficiency (VAD) was determined using the World Health Organization guidelines. A total of 3 200 elderly residents were included in the study. The serum retinol levels and prevalence of VAD and marginal VAD were also compared. Results: The serum retinol concentration (P(50)(P(25)-P(75))) of Chinese urban elderly residents was 1.83 (1.37-2.39) μmoL/L. Compared with middle-sized and small cities (1.91 (1.47-2.48) μmol/L), the retinol level of senior citizens in metropolis (1.70 (1.25-2.25) μmol/L) was significantly lower (P<0.001). The serum retinol levels of elderly male (1.89 (1.37-2.47) μmoL/L) was significantly higher than that of female (1.80 (1.36-2.28) μmoL/L) (P=0.001). The serum retinol concentration was 1.87 (1.42-2.43), 1.78 (1.32-2.33), and 1.71 (1.24-2.24) μmol/L for 60-69, 70-79, and ≥80 years olds, respectively. The retinol level in elderly people ≥70 years olds was significantly lower than that of 60-69 years olds (P<0.001). The overall prevalence of VAD among Chinese urban elderly residents was 4.22% (135/3 200); 6.00% (81/1 350) for metropolis residents and 2.92% (54/1 850) for middle-sized and small city residents. The overall marginal VAD rate of Chinese urban elderly residents was 8.19% (262/3 200); 10.51% (142/1 350) for metropolis residents and 6.49% (120/1 850) for medium-sized and small city residents. The prevalence of VAD and marginal VAD for males was 3.87% (61/1 577) and 8.24% (130/1 577), respectively (P<0.05). The prevalence of VAD according to age group was 3.65% (72/1 975), 4.96% (50/1 008), and 5.99% (13/217), respectively(P=0.097). The prevalence of marginal VAD according to age group was 6.99% (138/1 975), 9.82% (99/1 008), and 11.52% (25/217), respectively(P=0.05). Conclusion: Chinese urban elderly residents showed various levels of VAD, although marginal VAD was quite common. As VAD was more common in metropolis residents and older residents, specific strategies should target these populations.

The role of NdgR in glycerol metabolism in Streptomyces coelicolor

Streptomyces, which produces many pharmaceutical antibiotics and anticancer agents, is a genus of soil-dwelling bacteria with numerous regulators that control both primary and secondary metabolism. NdgR is highly conserved in Streptomyces spp. and is known to be involved in antibiotic production, tolerance against shock and physical stress, nitrogen metabolism, leucine metabolism, and N-acetylglucosamine metabolism. As another function of NdgR, we report the involvement of NdgR in glycerol metabolism in S. coelicolor. Initially, a glycerol utilization operon containing gylCABX was found to be up-regulated in an ndgR deletion mutant (BG11) grown in N-acetylglucosamine solid minimal media compared with wild-type strain (M145). BG11 produced more antibiotics with a small amount of glycerol and increased glycerol utilization, yielding higher concentrations of lactate and acetate per cell. Moreover, fatty acid production was also changed in BG11 to produce longer chain fatty acids, phenolic compounds, alkanes, and fatty alcohols. Using a gel retardation assay, NdgR was found to bind the upstream region of gylC, working as a repressor. NdgR is a second regulator of a glycerol utilization operon, for which only one regulator, GylR was previously known.

In-depth compositional analysis of water-soluble and -insoluble organic substances in fine (PM2.5) airborne particles using ultra-high-resolution 15T FT-ICR MS and GC×GC-TOFMS

Airborne particulate matter consisting of ionic species, salts, heavy metals and carbonaceous material is one of the most serious environmental pollutants owing to its impacts on the environment and human health. Although elemental and organic carbon compounds are known to be major components of aerosols, information on the elemental composition of particulate matter remains limited because of the broad range of compounds involved and the limits of analytical instruments. In this study, we investigated water-soluble and -insoluble organic compounds in fine (PM_2.5) airborne particles collected during winter in Korea to better understand the elemental compositions and distributions of these compounds. To collect ultra-high-resolution mass profiles, we analyzed water-soluble and -insoluble organic compounds, extracted with water and dichloromethane, respectively, using an ultra-high-resolution 15 T Fourier transform ion cyclotron resonance (15T FT-ICR) mass spectrometer in positive ion mode (via both electrospray ionization [ESI] and atmospheric pressure photoionization [APPI] for water-extracts and via APPI for dichloromethane-extracts). In conjunction with the FT-ICR mass spectrometry (MS) data, subsequent two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) data were used to identify potentially hazardous organic components, such as polycyclic aromatic hydrocarbons. This analysis provided information on the sources of ambient particles collected during winter season and partial evidence of contributions to the acidity of organic content in PM_2.5 particles. The compositional and structural features of water-soluble and -insoluble organic compounds from PM_2.5 particles are important for understanding the potential impacts of aerosol-carried organic substances on human health and global ecosystems in future toxicological studies.

Microbial biodiesel production from oil palm biomass hydrolysate using marine Rhodococcus sp. YHY01

The effect of various biomass derived inhibitors (i.e. furfural, hydroxymethylfurfural (HMF), vanillin, 4-hydroxy benzaldehyde (4-HB) and acetate) was investigated for fatty acid accumulation in Rhodococcus sp. YHY 01. Rhodococcus sp. YHY01 was able to utilize acetate, vanillin, and 4-HB for biomass production and fatty acid accumulation. The IC₅₀ value for furfural (3.1mM), HMF (3.2mM), vanillin (2.0mM), 4-HB (2.7mM) and acetate (3.7mM) was calculated. HMF and vanillin affect fatty acid composition and increase saturated fatty acid content. Rhodococcus sp. YHY 01 cultured with empty fruit bunch hydrolysate (EFBH) as the main carbon source resulted in enhanced biomass (20%) and fatty acid productivity (37%), in compression to glucose as a carbon source. Overall, this study showed the beneficial effects of inhibitory molecules on growth and fatty acid production, and support the idea of biomass hydrolysate utilization for biodiesel production by avoiding complex efforts to remove inhibitory compounds.

Functional Study of Lysine Decarboxylases from Klebsiella pneumoniae in Escherichia coli and Application of Whole Cell Bioconversion for Cadaverine Production

Klebsiella pneumoniae is a gram-negative, non-motile, rod-shaped, and encapsulated bacterium in the normal flora of the intestines, mouth, skin, and food, and has decarboxylation activity, which results in generation of diamines (cadaverine, agmatine, and putrescine). However, there is no specific information on the exact mechanism of decarboxylation in K. pnuemoniae. Specifically lysine decarboxylases that generate cadaverine with a wide range of applications has not been shown. Therefore, we performed a functional study of lysine decarboxylases. Enzymatic characteristics such as optimal pH, temperature, and substrates were examined by overexpressing and purifying CadA and LdcC. CadA and LdcC from K. pneumoniae had a preference for L-lysine, and an optimal reaction temperature of 37°C and an optimal pH of 7. Although the activity of purified CadA from K. pneumoniae was lower than that of CadA from E. coli, the activity of K. pneumoniae CadA in whole cell bioconversion was comparable to that of E. coli CadA, resulting in 90% lysine conversion to cadaverine with pyridoxal 5'-phosphate L-lysine.

Enhanced growth and total fatty acid production of microalgae under various lighting conditions induced by flashing light

Microalgae are gaining importance as a source of high-value bioproducts. However, data regarding optimization of algal productivity via variation of environmental factors are lacking. Here, we evaluated a novel lighting method for the enhancement of biomass and total fatty acid (TFA) productivities during algal cultivation. We cultivated six different algal strains (Chlorella vulgaris KCTC AG10002, Acutodesmus obliquus KGE18, Uronema sp. KGE03, Micractinium reisseri KGE19, Fragilaria sp., and Spirogyra sp.) under various lighting conditions-continuous light (CL), light-dark cycle (LD), and continuous dark (CD)-with or without additional flashing light. We monitored dry cell weight (DCW) and TFA concentrations during cultivation. For each algal strain, the growth rate showed markedly different responses to the various lighting modes. The growth rates of C. vulgaris KCTC AG10002 (1.34-fold DCW increase, LD with flash), A. obliquus KGE18 (5.16-fold DCW increase, LD with flash), Uronema sp. KGE03 (2.77-fold DCW increase, CL with flash), and M. reisseri KGE19 (1.52-fold DCW increase, CL with flash) markedly increased in response to flashing light. Additionally, in some algal strains cultivated under the LD mode, the flashing light treatment induced increased TFA concentrations (C. vulgaris, 1.19-fold increase; A. obliquus, 2.59-fold increase; and M. reisseri, 3.31-fold increase). Phytohormone analysis of M. reisseri revealed increases in growth rate and TFA concentrations, associated with phytohormone induction via flashing light (e.g. 2.93-fold increase in gibberellic acid); hence, flashing light can promote substantial alterations in algal metabolism.

[Post-marketing surveillance of Tanreqing injection in children: a real world study]

Objective: To evaluate the safety of Tanreqing injection among children in the real world. Methods: A multicenter, large sample, ambispective cohort study, with registration-type clinical safety monitoring. A total of 6 188 inpatients and patients from the emergency units, aged ≤ 14 years who all had been using Tanreqing injection in 59 secondary and tertiary hospitals in China, were recruited between January, 2014 and May, 2015. The main outcomes would include incidence and severity of adverse drug reaction (ADR)/adverse drug event (ADE) of Tanreqing injection. Univariate analysis was used to explain the risk factors of ADR. Results: The overall incidence of ADE was 4.20‰ (26 cases), including 4 serious ones. The incidence of ADR was 3.07‰ (19 cases), including 17 cases of general ADR and 2 cases of new ADR. All the ADR cases were mild or moderate, mostly showing damages in skin and appendages. The onset of disease happened in 24 hours after the Tanreqing injection but all the ADR cases got improved or cured. Having histories of allergies to drugs or foods would increase the incidence of ADR. Conclusion:Tanreqing injection caused low incidence of ADR in children. Progams as stratifying high-risk patients and improving administrative management could further increase the safety level of Tanreqing injection.

[Myoclonus and it's associated factors in Creutzfeldt-Jakob disease]

Objective: To analyze features and the related factors of myoclonus of 47 patients with probable or possible Creutzfeldt-Jakob disease (CJD). Methods: All patients diagnosed with"suspected CJD" and hospitalized in Xuanwu Hospital from January 2013 to November 2015 were included, and their clinical information and myoclonus features were analyzed. Age, clinical, course and manifestation, EEG, MRI, CSF14-3-3 features between myoclonus positive group and negative group were compared, and the correlation between myoclonus features and these factors was analyzed using Spearman correlation analyses. Results: (1) Occurrence rate of extrapyramidal symptoms (P=0.028), visual impairment (P=0.025) and dyssomnia (P=0.004) were higher in myoclonus positive group, the differences were significant. Spearman correlation analysis showed that myoclonus was related to extrapyramidal symptoms (P=0.024), visual impairment (P=0.030) and dyssomnia (P=0.001). (2) EEG features showed no significant difference between myoclonus positive and negative group. The 17 myoclonus positive patients were divided into three subgroups, typical EEG change group 52.94%(9/17), atypical EEG change group 23.53%(4/17) and no EEG change group 23.53%(4/17). Difference of myoclonus and other clinical manifestations were not significant among the three subgroups(P>0.05); correlation analysis also found no statistically significant correlation between myoclonus and EEG (P=0.201). Conclusions: Myoclonus often occurs after the damage of locomotor system (including pyramidal tract, extracorticospinal tract and cerebellum) among CJD patients, and it is related to extrapyramidal symptoms , visual impairment and dyssomnia . There is undefined correlation between myoclonus and periodic sharp wave complexes (PSWC) in EEG.

[The development of ex vivo lung perfusion in lung transplantation]

The shortage of donor lung remains one of the major problem for lung transplantation. With the development of modern lung preservation and repair technique, increasing marginal lung donors have been re-assessed and finally utilized for transplantation. The ex vivo lung perfusion technique (EVLP) was designed and has been developed for evaluation and repair of the lung. Nowadays, the indication of EVLP and the standard of qualified donor lung have reached a consensus according to the foreign publications. The EVLP system could be classified into three categories: the Toronto technique, the Lund technique and Hannover-Madrid technique. The major differences between the Toronto technique and the other two technique are the open left atrium status, the use of Steen solution mixed with erythrocyte and the perfusion at flows correspondent to 100% of the donor predicted cardiac output. With the accumulating experience, researchers have tried to imply some drugs in the circulation, modify the ventilation gas and delivery of adenoviral vector gene in order to improve the lung quality. But these are still in the research phase. Recently, the portable EVLP device has been developed and the lung preservation, assessment and repair could be conducted during transportation. So it could prolong the preservation time and expand the transportation distance of donor lung.

Biomass-derived molecules modulate the behavior of Streptomyces coelicolor for antibiotic production

Various chemicals, i.e., furfural, vanillin, 4-hydroxybenzaldehyde and acetate produced during the pretreatment of biomass affect microbial fermentation. In this study, effect of vanillin, 4-hydroxybenzaldehyde and acetate on antibiotic production in Streptomyces coelicolor is investigated. IC₅₀ value of vanillin, 4-hydroxybenzaldehyde and acetate was recorded as 5, 11.3 and 115 mM, respectively. Vanillin was found as a very effective molecule, and it completely abolished antibiotic (undecylprodigiosin and actinorhodin) production at 1 mM concentration, while 4-hydroxybenzaldehyde and acetate have little effect. Microscopic analysis with field emission scanning electron microscopy (FESEM) showed that addition of vanillin inhibits mycelia formation and increases differentiation of S. coelicolor cells. Vanillin increases expression of genes responsible for sporulation (ssgA) and decreases expression of antibiotic transcriptional regulator (redD and actII-orf4), while it has no effect on genes related to the mycelia formation (bldA and bldN) and quorum sensing (scbA and scbR). Vanillin does not affect the glycolysis process, but may affect acetate and pyruvate accumulation which leads to increase in fatty acid accumulation. The production of antibiotics using biomass hydrolysates can be quite complex due to the presence of exogenous chemicals such as furfural and vanillin, and needs further detailed study.

[Feature of magnetic resonance imaging in patients with Creutzfeldt-Jakob disease]

Objective: To assess the imaging features of 43 patients diagnosed as clinically possible or probable Creutzfeldt-Jakob disease (CJD) for providing referential information and experience on applications of MRI in the clinical diagnosis and treatment of CJD. Method: All patients who were diagnosed with "suspected CJD" and hospitalized in Xuanwu Hospital from January 2013 to November 2015 were collected, and their clinical information and MRI imaging features were analyzed retrospectively. Results: Totally 62 patients with "suspected CJD" were rectruited in this study, and 43 of them were diagnosied as probable and possible CJD when they were discharged.The typical MRI feature of CJD patients was "cortical ribbon" sign in MR DWI sequences and/or high signal in cortex or bilateral basal ganglia.In all patients, the simple coritcal involvement was the highest(76.47%, 26/34), followed by the cortical cortex and basal ganglia(23.53%, 8/34). MRI positive group had more prominent extrapyramidal symptoms than MRI negative group (26/31 vs 9/12, P=0.015), but no statistical difference in clinic feature was found between the group with simple cortex affected and the group with both cortex and bilateral basal ganglia affected (P>0.05). Conclusions: MRI images of patients with CJD have special characteristics and have corresponding changes when the patients are in different stages of disease. In combination with the clinical evaluation of disease progression, brain microscopic pathological changes of CJD patients can be assessed by regularly brain MRI examination.

Medium engineering for enhanced production of undecylprodigiosin antibiotic in Streptomyces coelicolor using oil palm biomass hydrolysate as a carbon source

In this study, a biosugar obtained from empty fruit bunch (EFB) of oil palm by hot water treatment and subsequent enzymatic saccharification was used for undecylprodigiosin production, using Streptomyces coelicolor. Furfural is a major inhibitor present in EFB hydrolysate (EFBH), having a minimum inhibitory concentration (MIC) of 1.9mM, and it reduces utilization of glucose (27%), xylose (59%), inhibits mycelium formation, and affects antibiotic production. Interestingly, furfural was found to be a good activator of undecylprodigiosin production in S. coelicolor, which enhanced undecylprodigiosin production by up to 52%. Optimization by mixture analysis resulted in a synthetic medium containing glucose:furfural:ACN:DMSO (1%, 2mM, 0.2% and 0.3%, respectively). Finally, S. coelicolor was cultured in a fermenter in minimal medium with EFBH as a carbon source and addition of the components described above. This yielded 4.2μg/mgdcw undecylprodigiosin, which was 3.2-fold higher compared to that in un-optimized medium.

Alginate/bacterial cellulose nanocomposite beads prepared using Gluconacetobacter xylinus and their application in lipase immobilization

Alginate/bacterial cellulose nanocomposite beads, with well-controlled size and regular spherical shapes, were prepared in a simple manner by entrapping Gluconacetobacter xylinus in barium alginate hydrogel beads, followed by cultivation of the entrapped cells in culture media with a low sodium ion concentration. The entire surface of the alginate hydrogel beads containing the cells was covered with cellulose fibers (∼30nm) after 36h of cultivation. The cellulose crystallinity index of the alginate/bacterial cellulose beads was 0.7, which was slightly lower than that of bacterial cellulose prepared by cultivating dispersed cells. The water vapor sorption capacity of the alginate/bacterial cellulose beads increased significantly from 0.07 to 38.00 (g/g dry bead) as cultivation time increased. These results clearly indicate that alginate/bacterial cellulose beads have a much higher surface area, crystallinity, and water-holding capacity than alginate beads. The immobilization of lipase on the surface of the nanocomposite beads was also investigated as a potential application of this system. The activity and specific activity of lipase immobilized on alginate/bacterial cellulose beads were 2.6- and 3.8-fold higher, respectively, than that of lipase immobilized on cellulose beads. The alginate/bacterial cellulose nanocomposite beads prepared in this study have several potential applications in the biocatalytic, biomedical, and pharmaceutical fields because of their biocompatibility, biodegradability, high crystallinity, and large surface area.

Neuropsychiatric manifestations in pediatric systemic lupus erythematosus: a 20-year study

The objective of this study was to investigate the manifestations, treatment and outcome of neuropsychiatric (NP) involvement in pediatric systemic lupus erythematosus (SLE) patients. The charts of 185 pediatric patients with SLE diagnosed between 1985 and 2005 in a tertiary referral hospital were retrospectively reviewed. NPSLE were defined using the American College of Rheumatology NPSLE case definitions. NPSLE developed in 34.6% (64/185) of the patients. The mean onset age was 15.2 years. Fourteen patients (21.9%) had NP manifestations on initial diagnosis of SLE. The median duration from the onset of SLE to NP manifestation was 11 months. The most frequent NP manifestations were seizure disorder (84.4%), ischemic stroke (28.1%) and psychosis (21.9%). However, the prevalence of manifestations of NPSLE might be underestimated by the retrospective design of our study. Higher mean C3/C4 levels, less percentage of anti-dsDNA antibodies elevation and higher percentage of elevated anticardiolipin antibodies were observed in NPSLE events than in non-NPSLE events ( P 0.05). The mortality rate of NPSLE patients decreased from 52.2% in 1985–1994 cohort to 27.8% in 1995–2005 cohort. In the past 10 years, the leading cause of death in NPSLE patients was NPSLE itself. NPSLE is common in pediatric SLE patients. It has diverse manifestations and a high mortality.

[Study of the genes correlated with cyst calcification in patients with cystic echinococcosis]

OBJECTIVE

To explore the genes (biomarkers) correlated with cyst calcification in patients with cystic echinococcosis (CE), and to provide the evidence for the judgment on the patients' prognosis at molecular level.

METHODS

The liver tissues from 32 patients with liver CE (10 cases for mRNA microarray and 22 cases for real-time PCR analysis) and 11 patients with hepatic cystadenoma were collected from three hospitals in Ningxia from June, 2013 to December, 2014. A comparison of the different gene-expressions between five patients with calcified lesions and five cases with no calcification was carried out using Significant Analysis of Microarrays (SAM) to select a subset of differentially expressed genes (DEGs) . Fold-change analysis was used to assess the changes of the expression quantity in the same genes between two groups. The verification was conducted among the liver tissues from 22 patients with liver CE (11 in the group of calcified or 11 in that of non-calcified) by real-time quantitative PCR (RT-qPCR). With GAPDH as a reference-gene and the liver tissues from 11 cases with hepatic cystadenoma as standardized control groups, the relative expressions of galecitin-4 (LGALS4) and acid ceramidase (ASAH1) in patients with calcified and non-calcified were calculated, respectively. The differences between two groups were compared using t'-test.

RESULTS

Five screened genes presented siginificantly different expressions all had showed the low-regulated expressions in the calcified group, with the most distinct low-regulation of LGALS4 and ASAH1 whose fold changes were 0.008 8, and 0.020 3, respectively. The verification by RT-qPCR illustrated that the relative expression of LGALS4 was showed at level of 0.49±0.27 amongst patients with calcified, and at level of 2.70±2.61 amongst non-calcified individuals,,indicating significant differences between two groups (t=-2.59, P=0.026); while the ASAH1 was relatively expressed at levels of 1.36±0.33 and of 1.68±0.67 amongst patients with calcified and non-calcified, respectively, showing insignificant changes statistically (t=-1.44, P=0.167). In the non-calcified group, both LGALS4 and ASAH1 genes expression quantities had a small fluctuation range, but with positively correlated trend (r=0.91, P=0.001), which indicated that a patient with the low LGALS4 expression quantity also had a relative low level of ASAH1 expression quantity.

CONCLUSIONS

Low expression quantity of LGALS4 and ASAH1 genes in patients with CE in the calcification might be potential biomarker for an indication of the disease self-healing.

Enhancing local luminescence in a hollow ZnO microcolumn by antiresonant reflecting

Hollow ZnO microcolumns with size induced photoluminescence and cathodoluminescence properties were prepared by a thermal chemical vapor transport and condensation method. It was found that the luminescence emission could be confined in the nano-sized hollow core and the wavelength dependent light intensity could be influenced by the geometric structure of the ZnO microcolumn, which can act as a hollow optical waveguide. Based on the antiresonant reflection in the optical waveguide, we established a theoretical model to address the field enhancement in the hollow ZnO microcolumn, which systematically clarifies the influence of the geometric structure of the microcolumn on the field enhancement. We report for the first time, the enhanced emission of the near ultraviolet light (working wavelength of 385 nm) along the axial direction of the ZnO microcolumn. The corresponding microsized light emitter has also been obtained. Experiments agree well with both theoretical predictions and computer simulations based on the finite-difference time-domain method with perfectly matched layer boundary conditions. These findings provide valuable information for the application of ZnO micro- and nanostructures in optoelectronic devices.