N-Heterocyclic Carbene-Catalyzed Formal Intramolecular [3 + 2] Annulations of Cyclohexadienone-Tethered Ynals.

A formal [3 + 2] annulation of cyclohexadienone-tethered ynals is enabled by an N-heterocyclic carbene (NHC) catalyst, affording a tricyclo[6.2.1.04,11]undecane framework. This study represents the first demonstration of using C═C double bonds as the reaction partner in the NHC-catalyzed annulation of ynals. This strategy is characterized by mild reaction conditions and 100% atom economy as well as high catalytic performance and efficiency.

Material Design of Ultra-Thin InN/GaN Superlattices for a Long-Wavelength Light Emission.

GaN heterostructure is a promising material for next-generation optoelectronic devices, and Indium gallium nitride (InGaN) has been widely used in ultraviolet and blue light emission. However, its applied potential for longer wavelengths still requires exploration. In this work, the ultra-thin InN/GaN superlattices (SL) were designed for long-wavelength light emission and investigated by first-principles simulations. The crystallographic and electronic properties of SL were comprehensively studied, especially the strain state of InN well layers in SL. Different strain states of InN layers were applied to modulate the bandgap of the SL, and the designed InN/GaN heterostructure could theoretically achieve photon emission of at least 650 nm. Additionally, we found the SL had different quantum confinement effects on electrons and holes, but an efficient capture of electron-hole pairs could be realized. Meanwhile, external forces were also considered. The orbital compositions of the valence band maximum (VBM) were changed with the increase in tensile stress. The transverse electric (TE) mode was found to play a leading role in light emission in normal working conditions, and it was advantageous for light extraction. The capacity of ultra-thin InN/GaN SL on long-wavelength light emission was theoretically investigated.

Theoretical Analysis and Numerical Simulation of the Wear of the Sealing Substrate of a High-Pressure, High-Frequency Opening and Closing Hydrogen Ball Valve.

High-pressure valves are an essential infrastructure for hydrogen refueling stations, and the issue of safety and reliability of their operation affects the efficiency of the entire hydrogen delivery system. Hydrogen ball valves are subjected to high-frequency, rapid reciprocating opening and closing for a long time, and the sealing surface between the valve seat and the ball has an uneven wear distribution problem. In this paper, a theoretical derivation of the seat wear volume and wear depth during the hydrogen ball valve adhesive wear process is presented, and a simulation model based on transient dynamics theory is established to carry out a nonlinear finite element analysis of the dynamic contact and frictional wear of the sealing structure during the opening and closing process of the hydrogen ball valve. In order to effectively reduce the wear unevenness of the sealing surface of the ball valve, a new type of valve seat sealing surface with an unequal-width structure is proposed. Comparing the sealing pressure and seat sealing surface wear depth of the ball valve before and after the improvement, the improved ball valve sealing performance is reliable, while the seat sealing surface wear distribution is more uniform.

A Highly Enantioselective Homoenolate Michael Addition/Esterification Sequence of Cyclohexadienone-Tethered Enals via NHC Catalysis.

Reported here is a highly enantioselective homoenolate Michael addition/esterification sequence of cyclohexadienone-tethered enals via N-heterocyclic carbene (NHC) catalysis, affording the enantiopure cis-hydrobenzofurans, cis-hydroindoles, and cis-hydroindenes. The NHC catalyst bearing a nitro group greatly enhances the stereocontrol, and a bulky N-aryl substituent of the triazolium salt in the catalyst is helpful for inhibiting the further aldol condensation after homoenolate Michael addition. The utility of this protocol is highlighted by a gram-scale experiment and versatile downstream transformations.

High-Efficient Spin Injection in GaN at Room Temperature Through A Van der Waals Tunnelling Barrier.

Achieving high-efficient spin injection in semiconductors is critical for developing spintronic devices. Although a tunnel spin injector is typically used, the construction of a high-quality tunnel barrier remains a significant challenge due to the large lattice mismatch between oxides and semiconductors. In this work, van der Waals h-BN films with the atomically flat interface were engaged as the tunnel barrier to achieve high spin polarization in GaN, and the spin injection and transport in GaN were investigated systematically. Based on the Hanle precession and magnetic resistance measurements, CoFeB was determined as an optimal spin polarizer, bilayer h-BN tunnelling barrier was proven to yield a much higher spin polarization than the case of monolayer, and appropriate carrier concentration as well as higher crystal equality of n-GaN could effectively reduce the defect-induced spin scattering to improve the spin transport. The systematic understanding and the high efficiency of spin injection in this work may pave the way to the development of physical connotations and the applications of semiconductor spintronics.

Cylindrical Al Nano-Dimer Induced Polarization in Deep UV Region.

The polarization properties of asymmetric plasmonic nanostructures originating from optical anisotropy show great application prospects in many fields, such as display, sensing, filtering, and detection. Here, we report the realization of polarization control in the deep ultraviolet (UV) region using Al nano-dimer structures. The simulation results indicated that the polarization effect was generated by the modulation of inter-coupling between the quadrupole plasmon resonances of the asymmetric dimer. By further optimizing the size and gap of the dimer, the extinction in the 200-nm deep UV region obtained a polarization ratio of 18%. This research is helpful for understanding the resonance hybridization of high-order surface plasmons in UV region and is of great significance to the emerging polarized micro-nano photonics fields, such as spin optoelectronics and deep UV optoelectronic devices.

Impact of accentuated cut edges (ACE) technique on volatile and sensory profiles of Shiraz wines.

Varietal thiols are important wine aroma compounds that are generally less abundant in red wines. Accentuated cut edges (ACE), known for accelerating phenolic extraction, was applied to Shiraz winemaking and compared with conventional crushing (NOACE) to examine the effects on varietal thiol precursor extraction and thiol formation. Water addition to grape must and skin contact time (SCT) during fermentation were also assessed. Although there was no difference for precursors in the must, ACE significantly decreased 3-S-glutathionylhexan-1-ol concentration during fermentation. 3-Sulfanylhexan-1-ol and ethyl esters were significantly influenced by crushing method and/or SCT, with NOACE or shorter SCT yielding higher concentrations. Acetates, higher alcohols, fatty acids, and isoprenoids differed according to the interaction of crushing method and SCT, with ACE and shorter SCT significantly enhancing all groups except acetates. Volatiles in Sauvignon blanc and Pinot noir wines produced at commercial scale with ACE were briefly evaluated, suggesting an impact of grape variety.

Molecular epidemiology of hepatitis B virus genotypes and subgenotypes in ethnic minority populations, Yunnan province, China.

The aim of our study was to determine the distribution of hepatitis B virus (HBV) genotypes and subgenotypes in ethnic minorities in Yunnan province to provide evidence supporting the theoretical basis for hepatitis B prevention and control. We obtained serum samples and demographic data from 765 individuals reported by Yunnan province who had either acute or chronic HBV infection and were from one of 20 ethnic minority populations: Achang, Bai, Brown, Tibetan, Dai, Deang, Dulong, Hani, Hui, Jingpo, Lahu, Yi, Lisu Miao, Naxi, Nu, Pumi, Wa, Yao, or Zhuang people. We sequenced the HBV DNA and determined the genotypes and subgenotypes of the isolated HBVs. We mapped the genotype and subgenotype distribution by ethnic minority population and conducted descriptive analyses. There were four genotypes among the 20 ethnic groups: genotype B (21.3% of samples), C (76.6%), D (1.8%) and I (0.3%). The most common subgenotype was C1. There were no genotype differences by gender (P = 0.954) or age (P = 0.274), but there were differences by region (P < 0.001). There were differences in genotype distribution (P < 0.001) and subgenotype distribution (P = 0.011) by ethnic group. Genotype D was most prominent in Tibet and most HBV isolates were C/D recombinant viruses. The only two genotype I virus isolates were in Zhuang people. Susceptibility and geographic patterns may influence HBV prevalence in different ethnic populations, but additional research is needed for such a determination.

Chemical and Sensory Impacts of Accentuated Cut Edges (ACE) Grape Must Polyphenol Extraction Technique on Shiraz Wines.

Accentuated Cut Edges (ACE) is a recently developed grape must extraction technique, which mechanically breaks grape skins into small fragments but maintains seed integrity. This study was the first to elucidate the effect of ACE on Shiraz wine's basic chemical composition, colour, phenolic compounds, polysaccharides and sensory profiles. A further aim was to investigate any potential influence provided by ACE on the pre-fermentation water addition to must. ACE did not visually affect Shiraz wine colour, but significantly enhanced the concentration of tannin and total phenolics. Wine polysaccharide concentration was mainly increased in response to the maceration time rather than the ACE technique. ACE appeared to increase the earthy/dusty flavour, possibly due to the different precursors released by the greater skin breakage. The pre-fermentation addition of the water diluted the wine aromas, flavours and astringency profiles. However, combining the ACE technique with water addition enhanced the wine textural quality by increasing the intensities of the crucial astringent wine quality sub-qualities, adhesive and graininess. Furthermore, insights into the chemical factors influencing the astringency sensations were provided in this study. This research indicates that wine producers may use ACE with pre-fermentation water dilution to reduce the wine alcohol level but maintain important textural components.

Potato Protein Fining of Phenolic Compounds in Red Wine: A Study of the Kinetics and the Impact of Wine Matrix Components and Physical Factors.

Producing wines within an acceptable range of astringency is important for quality and consumer acceptance. Astringency can be modified by fining during the winemaking process and the use of vegetable proteins (especially potato proteins) as fining agents has gained increasing interest due to consumers' requirements. The research presented was the first to investigate the effect of a potato protein dose on the kinetics of tannin and phenolic removal compared to gelatin for two unfined Cabernet Sauvignon wines. To further understand the results, the influence of the wine matrix and fining parameters (including pH, ethanol concentration, sugar concentration, temperature, and agitation) were tested according to a fractional 25-1 factorial design on one of the Cabernet Sauvignon wines using potato proteins. The results from the factorial design indicate that potato protein fining was significantly influenced by wine pH, ethanol concentration, fining temperature as well as an interaction (pH × ethanol) but not by sugar content or agitation. Insights into the steps required for the optimisation of fining were gained from the study, revealing that potato protein fining efficiency could be increased by treating wines at higher temperatures (20 °C, rather than the conventional 10-15 °C), and at both a lower pH and/or alcohol concentration.

A Ratiometric and Colorimetric Hemicyanine Fluorescent Probe for Detection of SO2 Derivatives and Its Applications in Bioimaging.

Based upon the intramolecular charge transfer (ICT) mechanism, a novel ratiometric fluorescent probe EB was developed to detect SO32-/HSO3-. The probe displayed both colorimetric and ratiometric responses toward SO32-/HSO3-. It displayed a quick response (within 60 s), good selectivity and high sensitivity (a detection limit of 28 nM) towards SO32-/HSO3-. The SO32-/HSO3- sensing mechanism was confirmed as the Michael addition reaction by ESI-MS. Moreover, the probe could be applied to measure the level of sulfite in real samples, like sugar and chrysanthemum, and it could also be used to detect SO32-/HSO3- in HepG2 cells through confocal fluorescence microscopy, which proved its practical application in clinical diagnosis.

Dynamic characterization of wine astringency profiles using modified progressive profiling.

Wine astringency is important for quality and consumer acceptance. Perception of this mouthfeel is temporal and can be separated further into unique textural sub-qualities. Quantitative data on these astringent sub-qualities in wine however are poorly understood. The aim of this study was to characterize the dynamic astringency profiles of 13 Australian commercial red wines and 2 rosés made from 11 grape varieties using modified progressive profiling by a trained sensory panel (n = 8). Seven attributes generated and defined by the panel (overall astringent intensity and 6 sub-qualities: pucker, mouth coat, dry, grippy, adhesive and graininess) were scored at six time periods (each lasting 10 s), with 20 s gap between each time period. Attributes were rated on 15 cm scales with anchors at 10 and 90% and samples were evaluated in duplicate. The wine composition as well as phenolic profiles were determined. Intensities of astringent sub-qualities were correlated with overall intensity, but the sub-quality profiles at a specific evaluation period and the progression of an attribute varied differently depending on the wine. The discrimination of wines at each time interval was dependent on attribute, and the relative importance of each astringent sub-quality varied at different evaluation periods. Correlations between mouthfeel attributes and chemical measures were established. This study demonstrated the utilisation of modified progressive profiling for wine astringency evaluation, providing a tool to capture quantitative data on astringent sub-qualities in wine.

Investigation of the risk factors associated with the failure of hepatitis B vaccination of neonates in Yunnan province, China.

OBJECTIVE: This study aimed to investigate HBsAg positive rates and risk factors of HBV infection among the children less than 15 years old in Yunnan province, a remote southwest part of mainland China. METHODS: Multi-stage sampling was used to randomly select study subjects from 9,360,000 individuals. Hepatitis B vaccine inoculation rate and HBsAg positive rate were investigated, and then propensity score and generalized linear mixed model (GLMMs) were applied to the case-control study. RESULTS: The average HBsAg positive rate was 1.81%, with 1.2% in urban areas and 2.4% in rural areas. Rate of first-dose-in-time in urban areas was 77.7%, obviously higher than 49.5% in rural areas (χ2=2811.71, P<0.01). Similarly, 3-dose completion coverage rate in urban areas was 93.7%, also higher than 79.0% in rural areas (χ2=1561.43, P<0.01). Maternal HBeAg positivity and HBsAg positivity were proved to be the main risk factors of children with HBV infection. Moreover, paternal HBeAg positivity, paternal HBsAg positivity, the absence and unknown status of HBV vaccine inoculation were risk factors of children with HBV infection as well. CONCLUSION: It was very important to improve the HBV vaccine inoculation rates. Delivering babies in hospital and timely inoculation with HBV vaccine were efficient ways to prevent HBV vertical transmission.

Risk factors related to the failure of prevention of hepatitis B virus Mother-to-Child transmission in Yunnan, China.

OBJECTIVE: To investigate the relationship between the failure of prevention of hepatitis B virus Mother-to-Child transmission and HBV serological pattern, viral load as well as HBV genotypes. METHODS: 2765 pairs of mother-infant matched samples were collected. These pregnant women were HBsAg positive and delivered at hospital from January 1st, 2011 to June 30th, 2011. Of these samples, 26 pairs of sera samples were randomly selected from 114 pairs of samples which failed in the prevention of hepatitis B virus Mother-to-Child transmission. Serological tests, viral load and genotype detection were performed for further analysis. Additionally, the selected subjects were followed and tested again in 2014. RESULTS: HBeAg positive rates were 76.92% and 69.23% in mother group and infant group respectively, showed no statistical difference. The average HBV DNA levels were >2×105IU/ml in both mother group and infant group. Genotype analysis revealed that 11 pairs of mother-infant matched samples belonged to C gene type and another 11 pairs were B gene type. Different genotypes were observed in 4 pairs of mother-infant matched samples. CONCLUSION: HbeAg positive and high HBV DNA level were two major risk factors of HBV mother to child transmission. Additionally, nosocomial infection was another potential way of HBV vertical transmission, especially in remote area of Yunnan province.

Determination of the concentration of alum additive in deep-fried dough sticks using dielectric spectroscopy.

The concentration of alum additive in deep-fried dough sticks (DFDSs) was investigated using a coaxial probe method based on dielectric properties in the 0.3-10-GHz frequency range. The dielectric spectra of aqueous solutions with different concentrations of alum, sodium bicarbonate, and mixtures thereof were used. The correspondence between dielectric loss and alum concentration was thereby revealed. A steady, uniform correspondence was successfully established by introducing ω·Îµâ€³(ω), the sum of dielectric loss and conductor loss (i.e., total loss), according to the electrical conductivity of the alum-containing aqueous solutions. Specific, resonant-type dielectric dispersion arising from alum due to atomic polarization was identified around 1 GHz. This was used to discriminate the alum additive in the DFDS from other ingredients. A quantitative relationship between alum and sodium bicarbonate concentrations in the aqueous solutions and the differential dielectric loss Δε″(ω) at 0.425 GHz was also established with a regression coefficient over 0.99. With the intention of eliminating the effects of the chemical reactions with sodium bicarbonate and the physical processes involved in leavening and frying during preparation, the developed technique was successfully applied to detect the alum dosage in a commercial DFDS (0.9942 g/L). The detected value agreed well with that determined using graphite furnace atomic absorption spectrometry (0.9722 g/L). The relative error was 2.2%. The results show that the proposed dielectric differential dispersion and loss technique is a suitable and effective method for determining the alum content in DFDSs.

Risk factors associated with immunoprophylaxis failure against mother to child transmission of hepatitis B virus and hepatitis B vaccination status in Yunnan province, China.

OBJECTIVE: To explore the risk factors associated with immunoprophylaxis failure against mother to child transmission of hepatitis B virus (HBV) and hepatitis B vaccination status in Yunnan province, China. METHODS: Multicenter cluster sampling was used to select pregnant women who were positive for hepatitis B surface antigen (HBsAg). HBV immunoprophylaxis was carried out for the newborns. Blood samples were collected and tested for HBV markers from 7 to 10 month old infants. The factors were analyzed by univariate and logistic regression. RESULTS: A total of 2765 mothers and their infants were enrolled. The failure rate of prevention of mother to child transmission (PMTCT) was 4.12%. The rate of timely HepB1 vaccination within 24h was 98.04%, the rate of three-dose vaccination was 92.30% and the rate of hepatitis B immune globulin (HBIG) administration was 68.97%. Place of residence, maternal education, gestational age and birth weight were related to administration of HBV immunoprophylaxis. It was remarkable that the rate of HBIG administration of infants was only 63.89% with whose mothers were both HBsAg and hepatitis B e antigen (HBeAg)-positive. Further analysis showed that there were three risk factors associated with HBV immunoprophylaxis failure: mothers who were positive for HBsAg and HBeAg, maternal HBVDNA level, and HBIG administration or not. CONCLUSIONS: PMTCT of HBV was well implemented in Yunnan. However, in order to achieve optimal prevention of vertical HBV transmission, it is mandatory to make additional efforts to improve the implementation of regulatory HBV immunoprophylaxis, especially for HBsAg-positive pregnant women.

[Evaluation on the efficacy of prevention programs and relevant factors targeting mother-to-infant transmission on hepatitis B virus in Yunnan province].

OBJECTIVE: To explore the efficacy of prevention programs and relevant factors targeting mother-to-infant transmission of HBV in Yunnan province. METHODS: In Yunnan province, we selected HBsAg positive pregnant women that delivered in hospital from January 1st through June 30th, 2011. Newborns of these pregnant women were under PMTCT (prevention of mother to child treatment) program and followed. Every infant was drawn 2 ml venous blood and questionnaire survey was carried out when the baby was 7-12 month-old and completed the vaccination processes. Serum samples of them were then collected and detected on the 5 serological indicators of HBV. RESULTS: were analyzed statistically. RESULTS: There were 2 765 infants in the study program. The success rate of PMTCT was 95.88% . Rates of coverage on both timely-birth dose and 3 doses of HepB were 97.03% and 92.30% respectively. The overall vaccinated rate and timely-birth vaccinated rate on hepatitis B immunoglobulin (HBIG) were 68.97% and 94.49% respectively. The success rate of PMTCT was 97.16% after administration of passive-active immune-prophylaxis (HepB and HBIG), compared to the rate as 93.01% when vaccinated with HepB only. Significant differences were seen in the successful rates of PMTCT between combined and non-combined immunization. Either the combined or non-combined immunization, there were significant differences seen in the success rates of PMTCT regardless the positivity status of HBsAg or HBeAg, among the infected mothers. CONCLUSION: The efficacy of passive-active immune-prophylaxis program seemed to be better than the one without combined immunization. It was vitally important for the infants whose mothers' HBsAg and HBeAg status were positive, to receive regular and timely combined immunization. In order to promote the PMTCT in Yunnan province, vaccinated rate on HBIG should be further improved.

Application of gas chromatography-quadrupole-time-of-flight-mass spectrometry for post-target analysis of volatile compounds in Fructus Amomi.

A post-target analysis method based on gas chromatography coupled to a high-resolution quadrupole time-of-flight mass analyzer is applied for the investigation of volatile compounds in Fructus Amomi. A series of narrow window extracted ion chromatograms at selected characteristic ions were performed. Chromatographic peaks with the same retention time in different extracted ion chromatograms was used to screen out the candidate compound. Identification was achieved by the accurate masses of several characteristic ions and the retention index of the peak. Forty six compounds, including 12 monoterpene compounds, were identified by conventional static headspace gas chromatography mass spectrometry and another six monoterpene compounds were found and identified by the post-target method. Post-target analysis is a useful strategy in qualitative research of natural products.

[Distribution of hepatitis B virus genotypes and serotypes in people who had a physical examination in Yunnan Province].

OBJECTIVE: To know genotypes and serotypes of hepatitis B virus (HBV) detected from hepatitis B infected people in Yunnan Province. METHODS: Serum samples were collected from HBsAg carriers detected from people who had a physical examination at Yunnan Provincial Center for Disease Control and Prevention. The S genes of HBV were amplified by nested PCR and the PCR products were sequenced. The viral genotype was identified by phylogenetic analysis. 27 reference sequences corresponding to HBV genotype A to I were obtained from GenBank. According to the amino acid sequences deduced from the nucleotide sequences of S gene, the dominant serotype of HBV detected from these people were confirmed. RESULTS: 39 HBsAg positive serum samples were detected from 2216 people who had a physical examination. The results shows that 76.9% were C genotype; 15.4% were B genotype; 5.1% were D genotype; 2.5% were I genotype. Three serotypes were found. The rates of adw2, adrq+ and ayr serotypes are 71.8%, 17.9% and 10.3% respectively. All of adw2 subtype specimens are C genotype. Among the serum specimens in which both HBsAg and HBeAg are positive, 75% were C genotype and adw2 subtype. CONCLUSION: It is determined that the main genotype and subtype of HBV prevailed in Yunnan province is C genotype and adw2 subtype.

[Molecular identification of hepatitis B virus genotype I in Yunnan Province, the People's Republic of China].

Molecular typing was conducted according to the reported method for one HBsAg positive carrier who had a physical examination in Yunnan Province. The S gene of this HBV sample was amplified by nested PCR and the PCR products were directly sequenced. Blast searching was done on the Genbank database and the sequence were compared with the HBV reference sequences in database. The phylogenetic tree was constructed. Homology analysis of nucleotide and smino acid were performed between the sequences from the sample and the reference sequences corresponding to HBV genotype A to I. Analysis of nucleotide and amino acid identities suggested that the sample belonged to HBV genotype I. The HBV genotype I is the first reported in China.