Involvement of Methoprene-tolerant and Krüppel homolog 1 in juvenile hormone-mediated vitellogenesis of female Liposcelis entomophila (End.) (Psocoptera: Liposcelididae).

Methoprene-tolerant (Met) as an intracellular receptor of juvenile hormone (JH) and the Krüppel-homolog 1 (Kr-h1) as a JH-inducible transcription factor had been proved to contribute to insect reproduction. Their functions vary in different insect orders, however, they are not clear in Psocoptera. In this study, LeMet and LeKr-h1 were identified and their roles in vitellogenesis and ovarian development were investigated in Liposcelis entomophila (Enderlein). Treatment with exogenous JH III significantly induced the expression of LeKr-h1, LeVg, and LeVgR. Furthermore, silencing LeMet and LeKr-h1 remarkably reduced the transcription of LeVg and LeVgR, disrupted the production of Vg in fat body and the uptake of Vg by oocytes, and ultimately led to a decline in fecundity. The results indicated that the JH signaling pathway was essential to the reproductive process of this species. Interestingly, knockdown of LeMet or LeKr-h1 also resulted in fluctuations in the expression of FoxO, indicating the complex regulatory interactions between different hormone factors. Besides, knockdown of both LeMet and LeKr-h1 significantly increased L. entomophila mortality. Our study provides initial insight into the roles of JH signaling in the female reproduction of psocids and provided evidence that RNAi-mediated knockdown of Met or Kr-h1 is a potential pest control strategy.

Effect of Ligand Structures on Ligand-Protected Gold Clusters: [Au-(p-/m-/o-MBT)]1-8 Clusters.

The controllable preparation of ligand-protected clusters is still an unresolved problem, which may be due to that their formation mechanism is unclear. We propose that the ligand is the key to solve the above problems. Here, by using p-, m-, and o-methylbenzenethiol ligand protected gold clusters as examples, we try to explore the effect of ligand structures on ligand-protected gold clusters. The geometrical structures, relative stabilities and surface properties of small-sized ligand-protected gold clusters [Au-SR]1-8 (SR = p-/m-/o-MBT) have been systematically studied based on the density functional theory. The results show that the ground state structures of [Au-SR]1-8 clusters tend to form closed rings except for [Au-SR]1,2. The different structures of ligand have significant effect on the structures and stabilities of ligand-protected clusters. By analyzing their surface properties and possible growth patterns, it is found that [Au-SR]1,2 clusters serve as the basic building blocks, and the larger clusters can be regarded as the combinations of them. This study provides some insights into the effect of ligands on ligand-protected clusters, which is useful for understanding the formation mechanism of ligand-protected clusters.

[Serum levels of 25-hydroxyvitamin D in children with attention deficit hyperactivity disorder].

OBJECTIVE: To examine serum 25-hydroxyvitamin D levels in children with attention deficit hyperactivity disorder (ADHD) and to explore the relationship between vitamin D level and ADHD. METHODS: Ninety-seven children with ADHD who were diagnosed according to DSM-V were selected as the ADHD group, including 46 cases of ADHD-I, 10 cases of ADHD-HI, and 41 cases of ADHD-C. Ninety-seven healthy children served as the control group. Serum levels of 25-hydroxyvitamin D were measured using electrochemiluminescence immunoassay. RESULTS: Mean serum levels of 25-hydroxyvitamin D in the ADHD group (17±7 ng/mL) were significantly lower than in the control group (23±8 ng/mL; P<0.01). The serum levels of 25-hydroxyvitamin D in the three subtypes groups of ADHD (ADHD-I, ADHD-HI, and ADHD-C) were all lower than in the control group (P<0.05). The rates of vitamin D insufficiency, deficiency or normal in the ADHD group were different from the control group (P<0.01). The distributions of vitamin D levels in the three subtypes groups of ADHD were all different from the control group (P<0.05). CONCLUSIONS: Serum levels of 25-hydroxyvitamin D in children with ADHD are lower than in healthy children, suggesting vitamin D level might be related to ADHD.

Structures, electrophilic properties, and hydrogen bonds of cytidine, uridine, and their radical anions: Microhydration effects.

Structures, electrophilic properties, and hydrogen bonds of the neutral and anionic monohydrated nucleoside, (cytidine)H2O, and (uridine)H2O have been systematically investigated using density functional theory. Various water-binding sites were predicted by explicitly considering the optimized monohydrated structures. Meanwhile, predictions of electron affinities and vertical detachment energies were also carried out to investigate their electrophilic properties. By examining the singly occupied molecular orbital and natural population analysis, we found the excess negative charge is localized on the cytidine and uridine moiety in anionic monohydrates. This may be the reason why the strength of hydrogen bonding undergoes an obvious change upon the extra electron attachment. Based on the electron density (ρ) and reduced density gradient (RDG), we present an approach to map and analyze the weak interaction (especially hydrogen bond) in monohydrated cytidine and uridine. The scatter plots of RDG versus ρ allow us to identify the different type interactions. Meanwhile, the maps of the gradient isosurfaces show a rich visualization of hydrogen bond, van der Waals interaction, and steric effect.

Formation and properties of iron-based magnetic superhalogens: a theoretical study.

In order to explore new magnetic superhalogens, we have systematically investigated the structures, electrophilic properties, stabilities, magnetic properties, and fragmentation channels of neutral and anionic Fe(m)F(n) (m = 1, 2; n = 1-7) clusters using density functional theory. Our results show that a maximum of six F atoms can be bound atomically to one Fe atom, and the Fe-Fe bonding is not preferred in Fe2F(n)(0/-) clusters. The computed electron affinities (EAs) indicate that FeF(n) with n ≥ 3 are superhalogens, while Fe2F(n) can be classified as superhalogens for n ≥ 5. To further understand their superhalogen characteristic, the natural population analysis charge distribution and the HOMOs of anionic clusters were also analyzed. When the extra negative charge and the content of HOMO are mainly located on F atoms, the clusters could be classified as superhalogens with EAs substantially surpass that of Cl. By calculating the binding energies per atom and the HOMO-LUMO gaps, FeF3, FeF4(-), Fe2F4, Fe2F5(-), and Fe2F7(-) clusters were found to have higher stabilities, corresponding to the Fe atoms that are attained at their favorite +2 and +3 oxidation states. Furthermore, we also predicted the most preferred fragmentation channel and product for all the ground state clusters. Even more striking is the fact that both neutral and anionic Fe(m)F(n) (m = 1, 2; n = 1-7) clusters carry large magnetic moments which mainly come from 3d orbital of iron atom.

Adsorption of sulfur on Au(111) surface: An extremely stable configuration.

The sulfur adsorption on gold surface is a hot topic in catalysis, electrochemistry and chemical sensors. However, the multiple structures of adsorbed sulfur and sulfur-induced reconstruction in gold substrate topography are still open problems until now. Here we performed an extensively study on sulfur adsorption on Au(111) surface based on First-Principles calculation. Our results show that the sulfur adsorption with additional Au atoms is not favorable. Thus, the well-known lifting of the herringbone reconstruction of Au(111) after sulfur adsorption can't be attributed to the lifting gold atoms. More importantly, we proposed an extremely stable configuration of S-Au(111) surface characterized by (√3 × âˆš3)R30° at 0.33 coverage, in which each S atom is chemisorbed in 3-fold coordinated sites and all the surface-Au atoms are terminated. Finally, the good agreement between our simulated STM and LEED images and experimental observations illuminates the truth that our proposed configuration is also favorable in experiment. This super stable S-adsorbed surface can be used as a starting point for the growth of two dimensional transition metal sulfides.

Soil microbial community characteristics and the influencing factors at different elevations on the eastern slope of Helan Mountain, Northwest China.

As an important bridge connecting aboveground communities and belowground biological processes, soil microorganisms play an important role in regulating belowground ecological processes. The altitudinal changes and driving factors of soil microbial community in mountain ecosystem in arid region are still unclear. We measured soil physicochemical properties at seven altitudes in the range of 1300-2800 m in Helan Mountains, and investigated the understory community composition, soil physicochemical properties, and soil microbial community. The driving factor for soil microbial community was explored by variance partitioning analysis and redundancy analysis. The results showed that the total amount of soil microorganisms and bacterial biomass first increased and then decreased with the increases of altitude, fungi, actinomyces, arbuscular mycorrhizal fungi, Gram-positive bacteria, and Gram-negative bacteria groups showed a gradual increase. The variation of fungal-to-bacterial ratio (F/B) along the altitude showed that the cumulative ability of soil bacteria was stronger than that of fungi at low altitudes, while the pattern is opposite at high altitudes. The ratio of Gram-positive bacteria to Gram-negative bacteria (GP/GN) showed an overall decreasing trend with the increases of altitude, indicating that soil bacteria and organic carbon availability changed from "oligotrophic" to "eutrophication" and from "low" to "high" transition as the altitude increased. Vegetation properties, soil physical and chemical properties jointly accounted for 95.7% of the variation in soil microbial community. Soil organic carbon (SOC), soil water content (SWC), and total nitrogen (TN) were significantly correlated with soil microbial community composition. Our results revealed the distribution pattern and driving factors of soil microbial communities at different elevations on the eastern slope of Helan Mountain, which would provide theoretical basis and data support for further understanding the interaction between plant-soil-microorganisms in arid areas.

Self-passivated edges of ZnO nanoribbons: a global search.

The edge structure of two-dimensional (2D) materials plays a critical role in controlling their growth kinetics and morphological evolution, electronic structures and functionalities. However, until now, the accurate edge reconstruction of ZnO nanoribbons remains absent. Here, we present results of a global search of ZnO edge structures having used the CALYPSO program combined with the density functional theory (DFT) method. In addition to a database of all the possible edge reconstructed structures of ZnO nanoribbons, the most stable edge reconstructed structures of armchair (ZnOAC), O-enriched zigzag (OZZ) and Zn-enriched zigzag edges (ZnZZ) have been confirmed based on molecular dynamics (MD) simulation and bonding configuration analysis of atoms near the edges. The edge formation energies show that their stabilities depend on the chemical potential (µO) and the concentrations (ρO) of oxygen atoms. Interestingly, a highly stable ZnZZ edge exhibits a novel nanotube-like structure and metallic characteristics, while the most stable reconstructed OZZ edge, resembling the letter "T", exhibits a narrow direct band-gap. It is almost certain that their electronic properties are determined by the edge states.

Geometries, stabilities, and electronic properties of Pt-group-doped gold clusters, their relationship to cluster size, and comparison with pure gold clusters.

A systematic study of bimetallic Au(n)M(2) (n = 1-6, M = Ni, Pd, and Pt) clusters is performed by using density functional theory at the B3LYP level. The geometric structures, relative stabilities, HOMO-LUMO gaps, natural charges and electronic magnetic moments of these clusters are investigated, and compared with pure gold clusters. The results indicate that the properties of Au(n)M(2) clusters for n = 1-3 diverge more from pure gold clusters, while those for n = 4-6 show good agreement with Au(n) clusters. The dissociation energies, the second-order difference of energies, and HOMO-LUMO energy gaps, exhibiting an odd-even alternation, indicate that the Au(4)M(2) clusters are the most stable structures for Au(n)M(2) (n = 1-6, M = Ni, Pd, and Pt) clusters. Moreover, we predict that the average atomic binding energies of these clusters should tend to a limit in the range 1.56-2.00 eV.

Equilibrium geometries, stabilities, and electronic properties of the bimetallic M2-doped Au(n) (M = Ag, Cu; n = 1-10) clusters: comparison with pure gold clusters.

The density functional method with relativistic effective core potential has been employed to investigate systematically the geometrical structures, relative stabilities, growth-pattern behaviors, and electronic properties of small bimetallic M(2)Au(n) (M = Ag, Cu; n = 1-10) and pure gold Au(n) (n ≤ 12) clusters. The optimized geometries reveal that M(2) substituted Au(n+2) clusters and one Au atom capped M(2)Au(n-1) structures are dominant growth patterns of the stable alloyed M(2)Au(n) clusters. The calculated averaged atomic binding energies, fragmentation energies, and the second-order difference of energies as a function of the cluster size exhibit a pronounced even-odd alternation phenomenon. The analytic results exhibit that the planar structure Ag(2)Au(4) and Cu(2)Au(2) isomers are the most stable geometries of Ag(2)Au(n) and Cu(2)Au(n) clusters, respectively. In addition, the HOMO-LUMO gaps, charge transfers, chemical hardnesses and polarizabilities have been analyzed and compared further.

Geometries, stabilities, and electronic properties of small anion Mg-doped gold clusters: a density functional theory study.

First-principle density functional theory is used for studying the anion gold clusters doped with magnesium atom. By performing geometry optimizations, the equilibrium geometries, relative stabilities, and electronic and magnetic properties of [Au(n)Mg]⁻ (n = 1-8) clusters have been investigated systematically in comparison with pure gold clusters. The results show that doping with a single Mg atom dramatically affects the geometries of the ground-state Au(n+1)⁻ clusters for n = 2-7. Here, the relative stabilities are investigated in terms of the calculated fragmentation energies, second-order difference of energies, and highest occupied−lowest unoccupied molecular orbital energy gaps, manifesting that the ground-state [Au(n)Mg]⁻ and Au(n+1)⁻ clusters with odd-number gold atoms have a higher relative stability. In particular, it should be noted that the [Au3Mg]⁻ cluster has the most enhanced chemical stability. The natural population analysis reveals that the charges in [Au(n)Mg]⁻ (n = 2-8) clusters transfer from the Mg atom to the Au frames. In addition, the total magnetic moments of [Au(n)Mg]⁻ clusters exhibit an odd-even oscillation as a function of cluster size, and the magnetic effects mainly come from the Au atoms.

[Attentiveness in school children: effect of cesarean section birth].

OBJECTIVE: To study the effect of cesarean section birth based on different indications on attentiveness in school children. METHODS: A total of 308 school children were assigned to three groups according to their birth model: natural delivery (n = 105), cesarean section due to social factors (n = 101) or medical factors (n = 102). The integrated visual and auditory continuous performance test (IVA-CPT) was performed for assessing attentiveness. RESULTS: The IVA-CPT demonstrated that there were significant differences in the quotients of combination control, auditory response control, combination attention, auditory attention, visual attention, auditory vigilance, visual concordance, visual vigilance and visual attention among the three groups (p<0.05). The results of the IVA-CPT in the group of cesarean section due to medical factors was obviously poorer than that of the natural delivery group and the group of cesarean section due to social factors. However no significant differences were observed between the groups of natural delivery and of cesarean section due to social factors. CONCLUSIONS: Cesarean section itself has no significant impacts on attentiveness in school children, while medical indications for cesarean section may contribute to major cause of attention deficit disorder.

[Comorbidities and behavioral problems in children with functional articulation disorder].

OBJECTIVE: To study the incidences of comorbidities and behavioral problems in children with functional articulation disorders. METHODS: One hundred and twelve children with functional articulation disorders (aged 4-11 years) were enrolled. Their comorbidities were identified based on clinical investigations and the DSM-IV diagnosis criteria of attention deficit hyperactivity disorder (ADHD), stuttering, tic disorders and enuresis. Behavioral problems were evaluated by the Conners Parent Symptom Questionnaire and the Child Behavior Checklist. RESULTS: Sixty-nine patients (61.6%) had one or more comorbidities. The incidence of comorbidity in children with middle-severe functional articulation disorders was higher than in those with mild disorders. The most common comorbidity was language impairment (30.4%), followed by stuttering (16.1%), enuresis (13.4%), and tic disorders (6.3%). In school age children, ADHD (47.5%) was the most common comorbidity. The incidence of behavioral problems was 40.2% by the Child Behavior Checklist and 57.1% by the Parent Symptom Questionnaire. CONCLUSIONS: The children with functional articulation disorders have high incidence of comorbidity and many behavioral problems.

CNTNAP2 Is Significantly Associated With Speech Sound Disorder in the Chinese Han Population.

Speech sound disorder is the most common communication disorder. Some investigations support the possibility that the CNTNAP2 gene might be involved in the pathogenesis of speech-related diseases. To investigate single-nucleotide polymorphisms in the CNTNAP2 gene, 300 unrelated speech sound disorder patients and 200 normal controls were included in the study. Five single-nucleotide polymorphisms were amplified and directly sequenced. Significant differences were found in the genotype (P = .0003) and allele (P = .0056) frequencies of rs2538976 between patients and controls. The excess frequency of the A allele in the patient group remained significant after Bonferroni correction (P = .0280). A significant haplotype association with rs2710102T/+rs17236239A/+2538976A/+2710117A (P = 4.10e-006) was identified. A neighboring single-nucleotide polymorphism, rs10608123, was found in complete linkage disequilibrium with rs2538976, and the genotypes exactly corresponded to each other. The authors propose that these CNTNAP2 variants increase the susceptibility to speech sound disorder. The single-nucleotide polymorphisms rs10608123 and rs2538976 may merge into one single-nucleotide polymorphism.

Probing the structural and electronic properties of small aluminum dideuteride clusters.

Adsorption of deuterium on the neutral and anionic Aln(λ) (n=1-9, 13; λ=0, -1) clusters has been investigated systematically using density functional theory. The comparisons between the Franck-Condon factor simulated spectra and the measured photoelectron spectroscopy (PES) of Cui and co-workers help to search for the ground-state structures. The results showed that D2 molecule tends to be dissociated on aluminum clusters and forms the radial AlD bond with one aluminum atom. By studying the evolution of the binding energies, second difference energies and HOMO-LUMO gaps as a function of cluster size, we found Al2D2, Al6D2 and Al7D2(̄) clusters have the stronger relative stability and enhanced chemical stability. Also, considering the larger adsorption energies of these three clusters, we surmised that Al2, Al6 and Al7(̄) may be the better candidates for dissociative adsorption of D2 molecule among the clusters we studied. Furthermore, the natural population analysis (NPA) and difference electron density were performed and discussed to probe into the localization of the charges and reliable charge-transfer information in AlnD2 and AlnD2(̄) clusters.

Mental health among left-behind preschool-aged children: preliminary survey of its status and associated risk factors in rural China.

OBJECTIVE: A large proportion of preschoolers have been left behind due to parental migration in rural China. We conducted a preliminary cross-sectional survey to investigate the mental health of these left-behind preschool-aged children (LBPC) and associated risk factors. METHODS: A total of 750 LBPC, comprising 217 and 433 children left behind as a result of migration of either or both parents, respectively, and 100 controls were enrolled from two counties in Anhui province, China. Their caregivers completed questionnaires on demographics, the Family Support Scale, the Parenting Self-efficacy Scale and the Preschool-aged Child Mental Health Scale. RESULTS: There were no significant differences in mental outcomes among the three groups. However, male LBPC who were younger, fostered by caregivers with lower levels of life satisfaction and parenting efficacy, and came from poorer families with less social support, experienced more mental health problems than other children. CONCLUSIONS: LBPC did not have worse mental well-being than their control counterparts, but some subpopulations were at potential risk of mental health problems compared with other LBPC. More research on other underlying factors and strategies to prevent the development of psychopathology is urgently needed.

A DFT study on equilibrium geometries, stabilities, and electronic properties of small bimetallic Na-doped Au(n) (n = 1-9) clusters: comparison with pure gold clusters.

A systematic study on the geometric structures, relative stabilities, and electronic properties of small bimetallic Au(n)Na (n = 1-9) clusters has been performed by means of first-principle density functional theory calculations at the PW91PW91 level. The results show that the optimized ground-state isomers adopt planar structures up to n = 5, and the Na-capped geometries are dominant growth patterns for n = 6-9. Dramatic odd-even alternative behaviors are obtained in the second-order difference of energies, fragmentation energies, highest occupied-lowest unoccupied molecular orbital energy gaps, and chemical hardness for both Au(n)Na and Au(n+1) clusters. It is found that Au(5)Na and Au(6) have the most enhanced stability. Here, the size evolutions of the theoretical ionization potentials are in agreement with available experimental data, suggesting a good prediction of the lowest energy structures in the present study. In addition, the charge transfer has been analyzed on the basis of natural population analysis.

Equilibrium geometries, stabilities, and electronic properties of the cationic Au n Be + (n = 1-8) clusters: comparison with pure gold clusters.

Ab initio method based on density functional theory at PW91PW91 level has been applied in studying the geometrical structures, relative stabilities, and electronic properties of small bimetallic Au(n)Be(+) (n = 1-8) cluster cations. The geometrical optimizations indicate that a transition point from preferentially planar (two-dimensional) to three-dimensional (3D) structures occurs at n = 6. The relative stabilities of Au(n)Be(+) clusters for the ground-state structures are analyzed based on the averaged binding energies, fragmentation energies, and second-order difference of energies. The calculated results reveal that the AuBe(+) and Au(5)Be(+) clusters possess higher relative stability for small size Au(n)Be(+) (n = 1-8) clusters. The HOMO-LUMO energy gaps as a function of the cluster size exhibit a pronounced even-odd alternation phenomenon. Sequently, the natural population analysis and polarizability for our systems have been analyzed and compared further.

Ab initio calculation of the geometries, stabilities, and electronic properties for the bimetallic Be2Au(n) (n = 1-9) clusters: comparison with pure gold clusters.

Ab initio methods based on density functional theory at BP86 level were applied to the study of the geometrical structures, relative stabilities, and electronic properties of small bimetallic Be(2)Au(n) (n = 1-9) clusters. The optimized geometries reveal that the most stable isomers have 3D structures at n = 3, 5, 7, 8, and 9. Here, the relative stabilities were investigated in terms of the averaged atomic binding energies, fragmentation energies and second-order difference of energies. The results show that the planar Be(2)Au(4) structure is the most stable structure for Be(2)Au(n) clusters. The HOMO-LUMO gap, vertical ionization potential, vertical electron affinity and chemical hardness exhibit a pronounced even-odd alternating phenomenon. In addition, charge transfer and natural electron configuration were analyzed and compared.

A systematic search for the structures, stabilities, and electronic properties of bimetallic Ca2-doped gold clusters: comparison with pure gold clusters.

The local meta-GGA exchange correlation density functional (TPSS) with a relativistic effective core potential was employed to systematically investigate the geometric structures, stabilities, and electronic properties of bimetallic Ca(2)Au( n ) (n = 1-9) and pure gold Au( n ) (n ≤ 11) clusters. The optimized geometries show that the most stable isomers for Ca(2)Au( n ) clusters have 3D structure when n > 2, and that one Au atom capping the Ca(2)Au( n-1) structure for different-sized Ca(2)Au( n ) (n = 1-9) clusters is the dominant growth pattern. The average atomic binding energies and second-order difference in energies show that the Ca(2)Au(4) isomer is the most stable among the Ca(2)Au( n ) clusters. The same pronounced even-odd alternations are found in the HOMO-LUMO gaps, VIPs, and hardnesses. The polarizabilities of the Ca(2)Au( n ) clusters show an obvious local minimum at n = 4. Moreover, the inverse corrections to the polarizabilities versus the ionization potential and hardness were found for the gold clusters.