Infall Signatures in a Prestellar Core Embedded in the High-mass 70 <i>μ</i>m Dark IRDC G331.372-00.116

Contreras, Yanett,Sanhueza, Patricio,Jackson, James M.,Guzmá,n, André,s E.,Longmore, Steven,Garay, Guido,Zhang, Qizhou,Nguyê,̃,n-Lu’o’, Quang,Tatematsu, Ken’ichi,Nakamura, Fumita American Astronomical Society 2018 The Astrophysical journal Vol.861 No.1

<P>Using Galactic Plane surveys, we have selected a massive (1200M circle dot), cold (14 K) 3.6-70 mu m dark IRDC, G331.372-00.116. This infrared dark cloud (IRDC) has the potential to form high-mass stars, and given the absence of current star formation signatures, it seems to represent the earliest stages of high-mass star formation. We have mapped the whole IRDC with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.1 and 1.3 mm in dust continuum and line emission. The dust continuum reveals 22 cores distributed across the IRDC. In this work, we analyze the physical properties of the most massive core, ALMA1, which has no molecular outflows detected in the CO (2-1), SiO (5-4), and H2CO (3-2) lines. This core is relatively massive (M = 17.6M circle dot), subvirialized (virial parameter alpha(vir) = M-vir/M = 0.14), and is barely affected by turbulence (transonic Mach number of 1.2). Using the HCO+ (3-2) line, we find the first detection of infall signatures in a relatively massive, prestellar core (ALMA1) with the potential to form a high-mass star. We estimate an infall speed of 1.54 km s(-1) and a high accretion rate of 1.96. x. 10(-3) M circle dot yr(-1). ALMA1 is rapidly collapsing, out of virial equilibrium, which is more consistent with competitive accretion scenarios rather than the turbulent core accretion model. On the other hand, ALMA1 has a mass similar to 6 times larger than the clumps Jeans mass, as it is in an intermediate mass regime (M-J = 2.7 < M less than or similar to 30 M circle dot), contrary to what both the competitive accretion and turbulent core accretion theories predict.</P>

Optical spectroscopy of PPV-based block copolymers of nanostructured supramolecular organic semiconductor.

Yang, Q,Battle, R,Zhang, C,Ma, S M,Seo, J T,Tabibi, B,Temple, D,Sun, S,Jung, S S,Namkung, M American Scientific Publishers 2009 Journal of nanoscience and nanotechnology Vol.9 No.2

<P>The third-order nonlinearity of a PPV-based nanostructured supramolecular organic semiconductor (DBAB), with an electron donor (D) connected to an electron acceptor (A) via nonconjugated and flexible bridge (B) units, was investigated in this work at both near-resonant (532 nm) and nonresonant (1064 nm) wavelength by using degenerate four-wave mixing. The second hyperpolarizabilities of D, A, and DBAB at 532 nm were found to be approximately 2.42 x 10(-43) m2/V2, 7.75 x 10(-44) m2/V2, and 1.80 x 10(-43) m2/V2 in copolarization geometry, and approximately 1.59 x 10(-43) m2/V2, 2.59 x 10(-44) m2/V2, and 1.18 x 10(-43) m2/V2 in orthogonal polarization geometry, respectively. The second hyperpolarizabilities of DBAB at 1064 nm were approximately 1.66 x 10(-46) m2/V2 and approximately 8.77 x 10(-47) m2/V2 for parallel and orthogonal polarization cases.</P>

Application of a sorbent trap system to gas-phase elemental and oxidized mercury analysis

Zhang, Z.,Eom, Y.,Lee, M.J.,Lee, T.G. Pergamon Press 2016 CHEMOSPHERE - Vol.154 No.-

A sorbent trap that utilizes activated carbon (AC) as the solid trapping medium is a new technology for measuring total mercury (Hg) emissions from combustion facilities. In this study, sorbent trap technology was further developed, improved and evaluated at the laboratory scale. AC was impregnated with 5% aqua regia to enhance its Hg adsorption capacity. Sorbent traps spiked with an Hg standard solution were found to be reproducibly prepared and highly stable. The effect of the Hg concentration on the spiking efficiency was further investigated. The adsorption of elemental and oxidized Hg by the sorbent trap was studied under various experimental conditions (temperature, flow rate and inlet Hg concentration). The Hg concentration of the flue gas effluent from the sorbent trap was measured. In addition, the concentration of Hg adsorbed on the AC was determined by digesting the used AC with an acid according to US EPA method 3052 and then analyzing it with cold vapor atomic absorption spectrometry. Furthermore, the gas-phase Hg emissions from a combustion source were measured using the sorbent trap according to US EPA method 30B. The results showed that the sorbent trap could be used for Hg concentrations between 10.0 and 40.0 μg m<SUP>-3</SUP> and flow rates between 0.5 and 1.0 lpm with adsorption efficiencies greater than 90%.

Quantifying herbicide dose-response and resistance in <i>Echinochloa</i> spp. by measuring root length in growth pouches

Zhang, C. J.,Lim, S. H.,Kim, J. W.,Song, J. S.,Yook, M. J.,Nah, G.,Valverde, B. E.,Kim, D. S. Canadian Science Publishing 2015 Canadian journal of plant science. Revue canadienn Vol.95 No.6

<P> Zhang, C. J., Lim, S. H., Kim, J. W., Song, J. S., Yook, M. J., Nah, G., Valverde, N. E. and Kim, D. S. 2015. Quantifying herbicide dose-response and resistance in Echinochloa spp. by measuring root length in growth pouches. Can. J. Plant Sci. 95: 1181-1192. The aim of the presented study was to develop a bioassay for rapid diagnosis of herbicide dose-response and resistance in Echinochloa. Pre-germinated seeds of Echinochloa spp. were incubated in growth pouches (18 cm×16.5 cm) containing herbicide solutions in a range of concentrations. Shoot and root lengths were measured after 6 d of incubation. Dose-responses estimated by measuring root lengths in the growth pouches were well-described by the log-logistic dose-response model and similar to those estimated by a whole-plant assay. Accurate dose-response curves were successfully generated for several herbicides with different modes of action, suggesting that the growth pouch method can be used for herbicide bioassays. The suitability of the growth pouch method for rapid diagnosis of acetyl coenzyme-A carboxylase (ACCase) and acetolactate synthase (ALS) inhibitor resistance in Echinochloa spp. was also tested. For cyhalofop-butyl, resistant and susceptible biotypes were discriminated at 180-300 mg a.i. L<SUP>−1</SUP> and 80-120 mg a.i. L<SUP>−1</SUP> for barnyardgrass (E. crus-galli) and late watergrass (E. oryzicola), respectively. For penoxsulam, the discriminatory dosage was 350-500 mg a.i. L<SUP>−1</SUP> for barnyardgrass and 650-1000 mg a.i. L<SUP>−1</SUP> for late watergrass. The method was further used to identify late watergrass biotypes resistant and susceptible to two other ALS inhibitors, azimsulfuron and bispyribac-sodium. Our results show that the growth pouch method can be reliably used in herbicide dose-response studies and to diagnose herbicide resistance in Echinochloa spp., with significant time and cost savings compared with conventional whole-plant assays. </P>

Association between PCR-RFLP Polymorphism of the Fifth Intron in Lipoprotein Lipase Gene and Productive Traits in Pig Resource Family

Zhang, B.Z.,Lei, M.G.,Deng, C.Y.,Xiong, Y.H.,Zuo, B.,Li, F.E. Asian Australasian Association of Animal Productio 2005 Animal Bioscience Vol.18 No.4

The study was aimed at detecting polymorphism of the fifth intron in lipoprotein lipase (LPL) gene and analyzing association between the polymorphism and productive traits. A pair of primers was designed for amplifying the fifth intron. Sequence analysis indicated that a G1171C substitution existed in Large White breed. The mutation was detected by PCR-AfaI-RFLP. Polymorphism analysis in a pig resource family showed that there existed significant effects on carcass and meat quality traits. Thoraxwaist fat thickness of BB genotype was significantly higher (14.2%, p<0.05) than that of AA on carcass traits, while BB genotype was significantly lower (3.6% p<0.01, 4.1% p<0.01; 2.3% p<0.01, 1.9% p<0.01; 1.8% p<0.01, 1.4% p<0.05) than AA and AB genotype in pH of m. Longissimus Dorsi (LD), m. Biceps Femoris (BF), m. Semipinali Capitis (SC). The allelic frequencies were also significantly different between indigenous Chinese breeds and exotic breeds. Data analyzed revealed that the mutation locus affected production traits mostly by additive effects. Based on these results, it is necessary to do more studies on LPL gene before making the LPL locus into the application of marker-assisted selection (MAS) programs.

Interfacial fabrication and property of hydroxyapatite/polylactideresorbable bone fixation composites

S.M. Zhang,J. Liu,W. Zhou,L. Cheng,X.D. Guo 한국물리학회 2005 Current Applied Physics Vol.5 No.5

Based on surface modication of hydroxyapatite with silane derivatives, interfacial fabrications of hydroxyapatite (HAP)/poly-lactide (PLA) resorbable bone xation composites are realized. The results indicate that interfacial adhesion, swelling property, andultimate mechanical properties of the HAP/PLA composites are signicantly improved. As a result, the maximum bending strengthenhances 27.8%. Scanning electron microscopy (SEM) observation suggests that the modied HA particles are homogeneously dis-persed in the composites, their size ranges are about 215l m. The modied HA/PLA composites are of toughened rupture. Thisconclusion is consistent with bending property of the composites. Finally, a possible mechanism for the interfacial adhesion is alsodiscussed..

Maternal Genetic Variants of IL4/IL13 Pathway Genes on IgE With “Western or Eastern Environments/Lifestyles”

Guicheng Zhang,Siew-Kim Khoo,Mika J Mäkelä,Pierre Candelaria,Catherine M Hayden,Leena von Hertzen,Tiina Laatikainen,Erkki Vartiainen,Jack Goldblatt,Tari Haahtela,Peter N LeSouëf1 대한천식알레르기학회 2014 Allergy, Asthma & Immunology Research Vol.6 No.4

Purpose: We investigated maternal genetic effects of four IL-4/IL-13 pathway genes as well as their interactions with the “Western or Easternlifestyles/environments” on IgE in Karelian children. Methods: This study included 609 children and their mothers. Total IgE levels in children andmothers were measured and 10 single nucleotide polymorphisms (SNPs) in IL-4, IL-4Ra, IL-13, and STAT6 were genotyped in mothers and their children. Results: The maternal G allele of IL-13 130 (rs20541) was significantly (P=0.001) associated with decreased IgE in children in the Karelianpopulation (Pooling Finnish and Russian children), as well as in Finnish (P=0.030) and Russian children (P=0.018). The IgE levels were significantly(P=0.001) higher in Russian children whose mothers were homozygous for the G allele of the IL-4Ra 50 (rs1805010) SNP than that in Russian childrenof mothers who were AG heterozygotes or AA homozygotes. After accounting for children’s genotypes, we observed interactive effects on children’sIgE for maternal IL-13 130 genotypes (P=0.014) and maternal IL-4Ra 50 genotypes (P=0.0003) with “Western or Eastern” lifestyles/environments. With the adjustment for multiple comparisons using a false discovery rate (FDR) of 0.05, the interactive effect of the maternal IL-4Ra 50 SNP wassignificant. Conclusion: Maternal genetic variants in IL-4/IL-13 pathway genes, such as IL-13 130 and IL-4Ra50, influenced IgE levels in schoolchildren that were independent of the children’s genetic effects. These effects differ in “Western or Eastern” environments.

Effects of Brazing Temperature on Microstructure and High-Temperature Strength of Joints Using a Novel Fourth-Generation Nickel-Based Single Crystal Superalloy

Z. P. Zhang,J. D. Liu,K. Q. Qiu,Y. Y. Huang,J. G. Li,X. G. Wang,J. L. Liu,M. Wang,M. K. Zou,Y. Z. Zhou 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.2

A novel fourth-generation nickel-based single crystal superalloy was bonded by vacuum brazing at 1230 °C, 1260 °C and1290 °C for 60 min using a new type of Co-based filler alloy. The effects of the brazing temperature on the microstructureand mechanical properties of the brazed joint were investigated. The brazed joint was mainly composed of the non-isothermalsolidification zone (M3B2 type-boride, CrB boride, Ni3Bboride and MC carbide), isothermal solidification zone (γ and γ'Phase) and base metal. With the increase of brazing temperature, the volume fraction of borides and γ' phase in the centerof the joint decreased and increased, respectively. The high-temperature tensile test results show that the tensile strength ofthe joints was improved with increasing brazing temperature, and the maximum tensile strength of the joint was 766 MPaafter brazing at 1290 °C for 60 min. Fracture observation shows that the fracture modes of the joints were the same, whichbelongs to the typical quasi cleavage fracture. The element distribution in the joint was homogenized to a certain extent at1290 °C. The segregation of Si and Ru was found, but they were still dissolved in the γ solid solution. The experimentalresults help to better understand the microstructure characteristics of the novel fourth-generation nickel-based single crystalsuperalloy and provide guidance for further optimizing the process parameters of the brazed joint.

High-efficiency p–i–n organic light-emitting diodes with a novel n-doping electron transport layer

Wei Xu,M.A. Khan,Yu Bai,X.Y. Jiang,Z.L. Zhang,W.Q. Zhu 한국물리학회 2009 Current Applied Physics Vol.9 No.4

We demonstrate p–i–n organic light-emitting diodes (OLEDs) incorporating an n-doping transport layer which comprises 8-hydroxy-quinolinato lithium (Liq) doped into 4'7-diphyenyl-1,10-phenanthroline (Bphen) as ETL and a p-doping transport layer which includes tetrafluro-tetracyano-quinodimethane (F4-TCNQ) doped into 4,4',4''-tris(3-methylphenylphenylamono) triphenylamine (m-MTDATA). In order to examine the improvement in the conductivity of transport layers, hole-only and electron-only devices are fabricated. The current and power efficiency of organic light-emitting diodes have been improved significantly after introducing a novel n-doping (Bphen: 33 wt% Liq) layer as an electron transport layer (ETL) and a p-doping layer composed of m-MTDATA and F4-TCNQ as a hole transport layer (HTL). Compared with the control device (without doping), the current efficiency and power efficiency of Device C (most efficient) is enhanced by approximately 51% and 89%, respectively, while driving voltage is reduced by 29%. This improvement is attributed to the improved conductivity of the transport layers that leads to the efficient charge balance in the emission zone. We demonstrate p–i–n organic light-emitting diodes (OLEDs) incorporating an n-doping transport layer which comprises 8-hydroxy-quinolinato lithium (Liq) doped into 4'7-diphyenyl-1,10-phenanthroline (Bphen) as ETL and a p-doping transport layer which includes tetrafluro-tetracyano-quinodimethane (F4-TCNQ) doped into 4,4',4''-tris(3-methylphenylphenylamono) triphenylamine (m-MTDATA). In order to examine the improvement in the conductivity of transport layers, hole-only and electron-only devices are fabricated. The current and power efficiency of organic light-emitting diodes have been improved significantly after introducing a novel n-doping (Bphen: 33 wt% Liq) layer as an electron transport layer (ETL) and a p-doping layer composed of m-MTDATA and F4-TCNQ as a hole transport layer (HTL). Compared with the control device (without doping), the current efficiency and power efficiency of Device C (most efficient) is enhanced by approximately 51% and 89%, respectively, while driving voltage is reduced by 29%. This improvement is attributed to the improved conductivity of the transport layers that leads to the efficient charge balance in the emission zone.

Structural characteristics and sodium penetration behaviors in anthracite cathodes: a combination study using Monte Carlo and molecular dynamics simulations

Daoush Walid M.,Li Jiaqi,Zhang Hongliang,Li Tianshuang,Xiao Jin 한국탄소학회 2020 Carbon Letters Vol.30 No.3

In aluminum electrolysis, sodium penetration into carbon cathodes is considered as the main cause of cell failure and ef�ciency loss, but the detailed mechanism is still not defnitely clear. Since the macroscopic properties of material depend on the microscopic structures, a large-scale atomistic model of anthracite cathodes was constructed to represent several important structural characteristics. Combined with Monte Carlo and molecular dynamics simulations, the adsorption and difusion behaviors of sodium were investigated, respectively. The results suggest that sodium adsorption mainly occurs in the larger micro-pores with the range of 10–19 Å, while it accords well with to type-I Langmuir adsorption model. The sodium is found to be preferentially adsorbed in arch-like structures with 5- or 7-membered rings or around heteroatom, especially oxygen. Moreover, the movements of sodium through carbon matrix mainly depend on the continuous difusive motion while most sodium particles tend to be trapped in voids with small mobility. The calculated transport difusion coefcient is equal to 6.132 × 10−10 m2 /s, which is in outstanding agreement with experimental results. This fundamental research would contribute to the understanding of sodium penetration mechanism and the optimization of cathode industry in the f