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This letter presents a 148–170‐GHz 4‐bit variable gain amplifier (VGA) with stagger‐tuning and multistage‐phase‐compensation techniques. In the design of this proposed VGA, phase variation is minimized by cascading overcompensation VGA and undercompensation VGA with reverse gain‐phase characteristics and phase suppression characteristics at sideband, achieved through different shunt inductors to ground. Additionally, stagger‐tuning technique has been introduced to realize VGA design. To prove these techniques, a 148–170‐GHz 4‐bit VGA has been fabricated in 0.13‐μm SiGe bipolar complementary metal‐oxide‐semiconductor (350/450 GHz ft/fmax) with a compact size of 0.165 mm2 $0.165 \,\text{mm}{}^{2}$. The results show the VGA achieves <4∘ $\lt {4}^{\circ }$ phase variation and over 10‐dB tuning range with 0.6‐dB gain step for a wide operating frequency from 148 to 170 GHz. The RMS gain error is <0.82 $\lt 0.82$ dB, the simulated input P1 dB ${P}_{1 \mathrm{dB}}$ is −10.5 $-10.5$ dBm and the total power consumption is 32.4‐mW with 2.25 V supply voltage. [ABSTRACT FROM AUTHOR]

This letter presents a compact lumped‐element two‐way differential to single‐ended Wilkinson power combiner with embedded impedance transformation. It consists of two transformer baluns and two parallel resistance and capacitor (RC) branches. The two transformers generate high‐order impedance transformation networks at even‐mode operation and form resonators together with the two parallel RC branches at odd‐mode operation, thus achieving broadband impedance matching and power combining with a compact area. A proof‐of‐concept prototype working at 1.7 GHz is designed and fabricated. Measurement results show that the peak isolation is 24.5 dB, insertion loss is from 0.34 to 1.15 dB and magnitude and phase imbalance are within 0.1 dB and 1∘ ${1}^{\circ }$, respectively, over the frequency range from 1.37 to 1.97 GHz. The area is only 6.54 mm × $\times $ 6 mm. [ABSTRACT FROM AUTHOR]

This letter presents a D‐band 5‐bit vector‐modulated phase shifter based on quadrature hybrids for D‐band phased arrays. The proposed vector‐modulated phase shifter employs two stages of quadrature hybrid followed with a single‐pole double‐throw switch for I/Q phase splitting and vector‐summing. To improve the isolation performance, traveling‐wave single‐pole double‐throw switches together with transistor parallel inductors are adopted. A marchand balun followed with two variable gain amplifiers is placed between the two quadrature hybrids for I/Q amplitude weighting. A proof‐of‐concept vector‐modulated phase shifter is designed and fabricated in 0.13 μm SiGe BiCMOS technology and occupies a core chip area of 0.45 mm2. Measurement results show that the RMS phase error is 1.6° at 149 GHz and the RMS gain error is below 2.8 dB over 146–156 GHz. The DC power consumption is 148 mW. [ABSTRACT FROM AUTHOR]

A self-embedding watermarking algorithm based on a reference sharing mechanism that has recovery ability under high tampering rates is proposed in this paper. In existing methods, the image recovery ability is often limited under an increasing tampering rate. The proposed method overcomes this limitation by seeking an approximate solution for each character-bit group tampered with. Moreover, the priority assignment of such groups can enhance the accuracy of tampering recovery. Based on this, by using the method proposed in this paper, recovered images always maintain excellent visual quality even at relatively high tampering rates. The experimental results demonstrate the efficacy of the proposed method. [ABSTRACT FROM AUTHOR]

The molecular structure of soil organic matter (SOM) is closely related to the structure and functions of the rhizosphere community. In this study, a microcosm experiment was conducted to investigate the effect of straw-derived biochar on the structural differentiation of SOM and rhizosphere bacterial communities. 13C NMR spectra showed that the relative abundance of carboxyl, alkyl, N-alkyl, O-alkyl and methoxyl groups decreased by 22%, 31%, 27%, 27% and 27%, respectively, and the relatively stable structure of aryl and O-aryl groups increased by 213% and 41%, respectively. In addition, network-based analysis showed that biochar amendment not only improved the network connectivity of the rhizosphere bacteria, but also enhanced the linkage between bacteria and the molecular structure of SOM. The topological properties of the network, including the number of edges, network density, and average clustering coefficient, were increased by 79%, 15% and 22%, respectively. Moreover, modularization analysis and structural equation model indicated that rhizosphere bacterial network was the important bio-factor affecting the content of labile carbon. Unlabelled Image • Biochar amendment strengthened network connectivity among rhizosphere bacteria. • The linkage between soil carbon and rhizosphere bacterial communities was enhanced by biochar. • Change of rhizosphere bacterial network was the important bio-factor affecting molecular structure of SOM. [ABSTRACT FROM AUTHOR]

• IR-driven strong plasmonic coupling is achieved on a metal/non-metal heterostructure system consisting of Ag nanorices and W 18 O 49 nanowires. • Plasmonic coupling on Ag/W 18 O 49 heterostructure enhances the local electric fields with magnitudes of 101-104 times of that of incident light. • Resonance excitation not only induces ultrafast electron transfer from W 18 O 49 to Ag, but photothermal effect to increase local temperature. • Upon focused sunlight irradiation, the Ag/W 18 O 49 film shows a remarkable photo/thermal enhancement of catalytic activity for H 2 evolution. Plasmonic coupling between two or more metal nanostructures has attracted significant interest, since this fascinating near-field interaction is more effective for the aggregation/magnification of the incident light intensity compared to normal surface-plasmon-resonance (SPR) of single nanostructures. Herein, we report, for the first time, an IR-driven strong plasmonic coupling in an unusual metal/non-metal heterostructure system. This system is fabricated through random assemblage of Ag nanorices (NRs) onto W 18 O 49 nanowires (NWs) film with F-doped SnO 2 glass as substrate. Through the 3D-finite element simulation, we demonstrate that the plasmonic coupling between Ag NRs and W 18 O 49 NWs significantly enhances the localized electric fields at the "hot spots". This achieved magnitudes of 101-104 times of that of incident light, thus leading to the promoted generation of plasmonic "hot-electrons". Moreover, the resonance excitation of plasmonic coupling on the heterostructures not only induces ultrafast electron transfer from W 18 O 49 to Ag hetero-components, but also the photothermal effect to increase the localized temperature. Upon SPR-coupling excitation, the Ag/W 18 O 49 heterostructures film exhibits a remarkable enhancement of the photo/thermal catalytic activity for H 2 evolution from ammonia borane compared to that of either the Ag NRs (˜8.2 ×) or W 18 O 49 NWs (˜9.0 ×) films. Notably, we observed an obvious H 2 evolution over the Ag/W 18 O 49 heterostructures film under natural sunlight irradiation. [ABSTRACT FROM AUTHOR]

Effective identification of the load torque is one of the key aspects in improving the performance of servo drive systems against load disturbances. Sliding mode variable structure control has become a popular method in the development of a load torque identification (LTID) algorithm due to its parameter insensitivity and easy realization features. However, existing LTID sliding mode observers (SMO) with conventional structure have the disadvantages of high-frequency chattering and poor estimation accuracy, which limit its application in high-performance servo systems. In this paper, the mathematical model of the conventional LTID-SMO is deduced and analyzed. A new LTID-SMO is proposed by replacing the sign function with a saturation function and an additional feedback loop in the load torque observer. The effectiveness of the proposed observer is verified by various experiments. The results show that compared to conventional load torque observer, the proposed observer can identify the load torque with higher accuracy and faster response in different operational conditions. [ABSTRACT FROM AUTHOR]

Abstract In this study, a novel carbon nanotube (CNT)-supported CuCo catalyst was successfully synthesized by wet impregnation. Experimental and theoretical results on catalytic deoxygenation of stearic acid, a model compound of microalgal bio-oil, revealed that the CuCo catalyst can effectively inhibit cracking reactions and promote production of diesel-like hydrocarbons. CuCo particles in the pores of CNTs were conducive to conversion of stearic acid to long-chain alkanes, featuring a high selectivity of 94.82% at 100% conversion. CuCo catalyst in oxidation state underwent fast in-situ reduction at the beginning of deoxygenation reaction, and its catalytic performance was comparable to that of reduced CuCo catalyst. The improved catalytic conversion of stearic acid to diesel-like hydrocarbons can be achieved at a high ratio of Cu0/(Cu++Cu0) and lattice Co atoms. In addition, the reduced H 2 pressure and amounts of catalysts show potential for large-scale industrial applications. Highlights • The CuCo catalyst can inhibit cracking and promote production of alkanes. • The CuCo catalyst can undergo fast in-situ reduction under reaction system. • Synergistic effect of Cu and Co mainly focuses on promoting reduction progress. • High ratio of Cu0/(Cu++Cu0) and lattice Co atoms are vital for catalytic activity. [ABSTRACT FROM AUTHOR]

Short-chain chlorinated paraffins are industrial contaminants of great concern due to their persistent and toxic characteristics. The predicted distribution of short-chain chlorinated paraffins in air, water, soils and sediments is unclear because their physiochemical properties are poorly known. Here, we calculated the coefficients that control the partitioning behaviors of 16 short-chain chlorinated paraffins. The results show an increase in partitioning coefficients with chlorine number for short-chain chlorinated paraffins with carbon chain length of 10. Mono-chlorinated short-chain chlorinated paraffins show an increase in partitioning coefficients with carbon number. Short-chain chlorinated paraffins with chlorines at both ends of the carbon chain have relatively lower values of logKow and logKoa. Results from the fugacity model show that mono-chlorinated short-chain chlorinated paraffins are likely to partition into water, whereas multi-chlorinated short-chain chlorinated paraffins are likely to partition into soil. [ABSTRACT FROM AUTHOR]

Plasmonic nanostructures have received significant attention in the field of solar-to-fuels conversion, because they can collect and utilize abundant low-energy photons to generate high-energy hot electrons for producing green chemical fuels. However, the ultrafast relaxation process of hot electron often leads to poor quantum yields of plasmonic nanostructures. Herein, we construct the one-dimensional W 18 O 49 /Carbon heterostructure for employing low-cost electrospun carbon fibers as the “electron mediator” to hinder the relaxation of hot electron in plasmonic W 18 O 49 nanowires. We confirm that the IR-excited plasmonic hot electrons in W 18 O 49 nanowires can quickly transfer to carbon fibers within only ∼50 fs in the W 18 O 49 /C heterostructure. This kinetics time is much shorter than the relaxation time of these hot electrons from high-energy surface plasmon (SP) to the ground state in W 18 O 49 nanowires (∼5.5 ps). As a result, upon low-energy IR-light excitation, the W 18 O 49 /C heterostructures exhibit nearly 2-fold enhancement on the catalytic H 2 production from ammonia borane as compared to single W 18 O 49 nanowires. Wavelength-dependent catalytic tests further indicate that this plasmon-enhanced catalytic activity is induced by the ultrafast transport process of plasmonic hot electron due to the localized surface plasmon resonance. [ABSTRACT FROM AUTHOR]

Abstract: Plasmonic metal nanostructures have been widely used to enhance the upconversion efficiency of the near‐infrared (NIR) photons into the visible region via the localized surface plasmon resonance (LSPR) effect. However, the direct utilization of low‐cost nonmetallic semiconductors to both concentrate and transfer the NIR‐plasmonic energy in the upconversion system remains a significant challenge. Here, a fascinating process of NIR‐plasmonic energy upconversion in Yb3+/Er3+‐doped NaYF4 nanoparticles (NaYF4:Yb‐Er NPs)/W18O49 nanowires (NWs) heterostructures, which can selectively enhance the upconversion luminescence by two orders of magnitude, is demonstrated. Combined with theoretical calculations, it is proposed that the NIR‐excited LSPR of W18O49 NWs is the primary reason for the enhanced upconversion luminescence of NaYF4:Yb‐Er NPs. Meanwhile, this plasmon‐enhanced upconversion luminescence can be partly absorbed by the W18O49 NWs to re‐excite its higher energy LSPR, thus leading to the selective enhancement of upconversion luminescence for the NaYF4:Yb‐Er/W18O49 heterostructures. More importantly, based on this process of plasmonic energy transfer, an NIR‐driven catalyst of NaYF4:Yb‐Er NPs@W18O49 NWs quasi‐core/shell heterostructure, which exhibits a ≈35‐fold increase in the catalytic H2 evolution from ammonia borane (BH3NH3) is designed and synthesized. This work provides insight on the development of nonmetallic plasmon‐sensitized optical materials that can potentially be applied in photocatalysis, optoelectronic, and photovoltaic devices. [ABSTRACT FROM AUTHOR]

Here, we developed a new kind of hetero-structural catalyst through the homogeneous growth of Cu-ZSM-5 zeolite onto silicon carbide (SiC) monolith by using a one-pot hydrothermal method combined with an ion-exchange process in a rotary oven. The new catalyst formulation was tested towards NH 3 -SCR, where the catalytic activity and stability of Cu-ZSM-5/SiC at T > 350 °C appear significantly higher than those obtained with Cu-ZSM-5 alone. In particular, the NO consumption rate of the former is 7.5 times larger on the average than that of the latter. This remarkable enhancement of catalytic activity is ascribed to the very good thermal conductivity of the SiC monolithic support. This research work could provide the means for the future design of more active and stable monolithic Cu-ZSM5-based catalytic systems with even lower Cu loading than the ones used in present de-NO x applications. [ABSTRACT FROM AUTHOR]

Focusing properties of vector Bessel–Gauss (BG) beam with multiple-annular phase wavefront is investigated by vector diffraction theory in this article. The multiple-annular phase wavefront modulation is given by a function of radial direction angle and m. It was found that the focal properties can be altered considerably by the multiple-annular phase wavefront modulation parameter m, including the shape, size and focus shifts are variable with the change of parameters. There is an remarkable phenomenon that both the focal region and the gradient force distribution are symmetrical about the horizontal axis. In a word, the properties of the vector Bessel–Gauss (BG) beam with multiple-annular phase wavefront are considerably altered by the multiple-annular phase wavefront parameters, especially influenced the shape of focal region, and the quantity of intensity peak, but having no influence on the symmetry. [ABSTRACT FROM AUTHOR]

Radially polarized helico-conical Lorentz-gauss beam with radial phase wavefront modulation can change the optical properties of the focal region in focusing optical system, which has tremendous research significance and application value in a host of territories, such as exotic optics, optical micromanipulation and so on. In this paper, by the utilization of the vector diffraction theory, the focusing properties of radially polarized helicon-conical Lorentz-Gauss beam with radial phase wavefront are investigated theoretically and numerically. Results show that focus shift is considerably influenced by changing the charge number m, eccentric parameter K, the numerical aperture NA and the radial phase parameter n, and simultaneously, unconspicious changes can be observed if we only alter the radial phase parameter m without the changes of m, K or the numerical aperture NA. [ABSTRACT FROM AUTHOR]

Aim: A-nine month of field trail was conducted to investigate the accumulation capacity of cadmium and zinc by Arabidopsis halleri spp. germmifera. Methods: An experimental site moderately contaminated with Zn and Cd was chosen to evaluate the field traits of seed sowing and seedling transplantation. The exchangeable fraction and total Cd and Zn in the soil and the concentration in harvested plants were determined by inductively coupled plasma mass spectrometer. Results: The shoot biomass of A. halleri ssp. germmifera increased after more than 8 months of cultivation, and it was approximately 2.13 t ha in the seedling transplantation group, which was more than three times higher than in the seed sowing group. The lower ratio of Zn/Cd concentration in plants than in the soil and the higher bioaccumulation factor indicated that A. halleri ssp. germmifera has a higher uptake efficiency for Cd than for Zn. In total, A. halleri ssp. germmifera removed 18.20 kg Cd ha and 27.38 kg Zn ha from the soil. After nine months of growth, A. halleri ssp. germmifera extracted (22.87 ± 9.21) % of total Cd concentration and (2.99 ± 0.94) % of total Zn concentration from the soil. However, no significant decrease of exchangeable concentration was shown in soil Cd and Zn, which revealed that the uptake of Cd and Zn by A. halleri ssp. germmifera not only came from exchangeable forms but also from non-exchangeable fractions. Conclusions: The results of present study indicated that A. halleri ssp. germmifera can be used to efficiently remove different forms of Cd from contaminated land. [ABSTRACT FROM AUTHOR]

Rational arrangement of nanosized semiconductor components in the multi-heterojunction photocatalyst can lead to the formation of a high-speed transport channel for charge-carriers separation and migration, which provides a promising way to achieve excellent photocatalytic efficiency for solar fuels generation. Herein, we develop a photo-assisted self-optimization strategy to re-build the charge-carriers transport channel in the copper species nanocrystals/TiO 2 electrospun nanofibers with the organic hydrogen-carrier molecules as the photo-reactants. As a result of the dynamics difference of the excitons migration during the photocatalytic process, the binary CuO/TiO 2 heterojunction nanofibers are recrystallized to form the quaternary Cu/Cu 2 O/CuO/TiO 2 multi-heterojunction nanofibers that exhibits a higher rate constant ( ∼ 1.7 × 10 8 S − 1 ) for the interfacial electron-transfer than the former nanofibers ( ∼ 0.7 × 10 8 S − 1 ) due to the improved charge-carriers transport channel. In this way, a 40-fold enhanced H 2 generation rate was observed on the recrystallized nanofibers photocatalyst during the photocatalytic decomposition of formic acid as compared to the pure TiO 2 nanofibers. Our work presents an available paradigm to skillfully use a transient photo-physicochemical process to mildly engineer a high-quality charge-carriers transport channel in the hetero-nanophotocatalyst for realizing an optimal photocatalytic performance. [ABSTRACT FROM AUTHOR]

The synthesized Si/TiO SB 2 sb heterostructure possessed the higher photoelectric catalytic and photocurrent activities than the other control samples (porous Si and nonporous Si/TiO SB 2 sb heterostructure) upon simulated solar light and visible light irradiation due to its porous structure and heterojunction effect. In the article "Facile-Controlled Epitaxial Growth Direction of Heterogeneous Core/Shell Structured NaLnF SB 4 sb Nanocrystals through Traditional Methods", B. Xu et al. reported the controllable synthesis of heterogeneous core/shell structured NaLnF SB 4 sb nanocrystals (NaYF SB 4 sb /NaNdF SB 4 sb ) with different outer layer growth directions via the coprecipitation process combined with the thermal decomposition method. In the article "Photoelectrochemical Properties of Porous Si/TiO SB 2 sb Nanowire Heterojunction Structure", J. Wang et al. synthesized the Si/TiO SB 2 sb heterostructure through assembling TiO SB 2 sb -nanowire layer onto the porous silicon substrate by using the hydrothermal method and the metal-assisted chemical etching method. [Extracted from the article]

Direct evidence of plasmon-enhanced 4-nitrophenol (4-NP) reduction is observed in a photo-assisted catalytic process with the NaBH 4 as the electron donator by using the Ag nanoparticles (AgNPs) supported onto a flexible and processable polyacrylonitrile (PAN) microfibrous network. The Ag/PAN composite fibrous networks exhibit certain activity for 4-NP reduction in general condition. Significantly, when the beam irradiation is introduced to excite the surface plasmon resonance (SPR) of AgNPs, we observed an enhanced catalytic activity for 4-NP reduction (1 ∼ 3 times). Meanwhile, the enhancement factors for the catalytic kinetic constants are directly correlated with the SPR absorption spectra of AgNPs. Further in-depth studies by adjusting the experiment conditions reveal that the SPR-induced ultrafast thermal effect of AgNPs is responsible for the enhanced catalytic activity that can not be nevertheless initiated or magnified by the hot plasmonic electrons from Ag. By combining with the theoretical analyses, we propose that this plasmon enhancement is ascribed to the promoted diffusion rate of reactants in the solution driven by increasing the local temperature around the AgNPs on the basis of SPR-enhanced electric field. Our present work provides a new sight to understand the plasmonic enhancement of metal-related catalytic reactions, and would also create more opportunities to guide the design and fabrication of high-performance plasmonic catalysts with excellent recycling property. [ABSTRACT FROM AUTHOR]

Heat-assisted magnetic recording (HAMR) has become one of the leading approaches to increase the areal density in hard disk drives to several Tb/in2. Laser-induced protrusion significantly impacts the HAMR heads’ performance and lifetime. Nonetheless, the pointy local protrusion amount is hard to accurately quantify by touchdown sensors. Based on the previous indirect thermal-mechanical studies with different sensors and techniques, a new methodology is developed to measure the laser-induced protrusion by burnishing the head during writing with laser powered ON and by utilizing atomic force microscopy scans. This burnish method requires the air-bearing surface (ABS) to physically contact the rotating disk without an excessive overdrive, which relies on the precise settings of the touchdown sensors and the detection methods. The time dependence of the burnish behavior is studied. The results show that its time constant is much longer than the pure thermal and mechanical time constants. The repeatability of the experiment is validated. The local protrusion induced by the laser is in the range of 2–5 nm based on current head design. Accordingly, the detailed studies about heater power effects and protrusion amount as a function of laser power have been conducted. In addition, the impact of varying degrees of stiffness of the ABS is discussed. [ABSTRACT FROM AUTHOR]

The photocatalytic activity of a semiconductor is heavily influenced by its photocatalytic cumulative effect on the four consecutive photo-physiochemical processes, including light harvesting, charge separation, charge migration, and charge utilization. Herein, we proposed and synthesized the well-designed plasmonic Au@Pt/CdS/C 3 N 4 heterostructure to enhance the photocatalytic cumulative effect by simultaneously sensitizing the total four processes. [Display omitted] • Pt/CdS-selective-coated Au nanocubes are assembled onto C 3 N 4 nanosheets. • Plasmon-enhanced photocatalytic cumulative effect on the Au@Pt/CdS/C 3 N 4 heterostructure. • Plasmon-induced HET, RET, and LEFE processes are achieved simultaneously. • Photocatalytic activities of H 2 generation and CO 2 reduction are remarkably enhanced. The photocatalytic activity of a semiconductor is heavily influenced by its photocatalytic cumulative effect on the four consecutive photo-physiochemical processes, including (I) light harvesting, (II) charge separation, (III) charge migration, and (IV) charge utilization. However, it is still a tremendous challenge to enhance the photocatalytic cumulative effect by simultaneously sensitizing the total above I-IV processes of the semiconductor. Herein, we synthesized the well-designed plasmonic Au@Pt/CdS/C 3 N 4 heterostructure through assembling Pt/CdS-selective-coated Au nanocubes onto the two dimensional (2D) ultrathin C 3 N 4 nanosheets (NSs). We have also demonstrated that selectively coating CdS nanoparticle-clusters (NPCs) and Pt nanoparticles (NPs) onto the surfaces and edges of Au NCs could boost the II and III processes of the formed Au@Pt/CdS NCs based on the resonance energy transfer (RET) and "hot electron" transfer (HET) behaviors, respectively, due to the localized surface plasmon resonance (LSPR) of Au NCs. The assembly of the Au@Pt/CdS NCs onto the C 3 N 4 NSs formed lots of 2D Au/CdS/C 3 N 4 interface, where the Au-LSPR not only boosted the I process at the "type II" heterojunction regions of CdS/C 3 N 4 , but also improved the II process of C 3 N 4 NSs via the local electromagnetic field enhancement (LEFE). Furthermore, the quasi-2D porous structure of CdS NPCs increased the surface active-sites at the 2D CdS/C 3 N 4 interface, therefore enhancing the IV process. As such, when normalizing the effective active area as the Au@Pt/CdS/C 3 N 4 hetero-interface region, the plasmonic heterostructure exhibited the ∼ 17.2-fold and ∼ 14.3-fold enhancements on the photocatalytic H 2 evolution and CO 2 reduction as compared to the CdS/C 3 N 4 heterojunction, respectively. [ABSTRACT FROM AUTHOR]

In this work, we present the 2D/2D type of heterojunction photocatalysts fabricated by horizontal loading ultrathin hexagonal SnS 2 nanosheets on g-C 3 N 4 nanosheets through a facile ultrasonic dispersion method. The sheet-like structures of these two nanomaterials induce a large contact region in the heterojunction interface, as evidenced by electron microscopic analyses. By taking advantage of this feature, the as-fabricated SnS 2 /g-C 3 N 4 heterojunction nanosheets exhibit considerable improvement on the photocatalytic activities for the degradation of organic dyes and phenols under visible light irradiation as compared to pure g-C 3 N 4 and SnS 2 nanosheets. In particular, the optimal heterojunction nanosheet with 5.0 wt.% SnS 2 shows the apparent rate constant of ∼0.2 min −1 for the RhB photodegradation, which is higher than that of pure g-C 3 N 4 and SnS 2 nanosheets by a factor of 4 and 8, respectively. Further studies by steady-state and transient photoluminescence spectroscopy indicate that the photosynergistic effect of SnS 2 /g-C 3 N 4 heterojunction can remarkably enhance the photoinduced interfacial charge transfer, thereby increasing the charge separation during the photocatalytic reaction. [ABSTRACT FROM AUTHOR]

ScoMcrA is a type IV modification-dependent restriction endonuclease found in the model strain Streptomyces coelicolor. Unlike type I, II and III restriction endonucleases, which cleave unmodified DNA, type IV restriction endonucleases cleave modified DNA, including methylated, hydroxymethylated, glucosyl-hydroxymethylated and phosphorothioated DNA. ScoMcrA targets both Dcm-methylated DNA and phosphorothioated DNA, and makes double-strand breaks 16-28 nt away from the modified nucleotides or the phosphorothioate links. However, the mechanism by which ScoMcrA recognizes these two entirely different types of modification remains unclear. In this study, the ScoMcrA protein was overexpressed, purified and crystallized. The crystals diffracted to 3.35 Å resolution and belonged to space group P212121. The unit-cell parameters were determined to be a = 130.19, b = 139.36, c = 281.01 Å, α = β = γ = 90°. These results will facilitate the detailed structural analysis of ScoMcrA and further elucidation of its biochemical mechanism. [ABSTRACT FROM AUTHOR]

We present high-yield hydrogen production through selective photocatalytic decomposition of formic acid by using electrospun TiO 2 nanofibers decorated with AuPd bimetallic alloy nanoparticles under simulated sunlight irradiation. By using only 5 mg of the AuPd/TiO 2 nanofibers containing the 0.75% Au and 0.25% Pd, we could achieve an optimal H 2 generation rate of 88.5 μmol h −1 with an apparent quantum yield at 365 nm as 15.6%, which is higher than that of the Pd/TiO 2 and Au/TiO 2 nanofibers by a factor of 1.6 and 4.5, respectively. The enhanced photocatalytic decomposition of formic acid for H 2 generation could be attributed to the stronger electron-sink effect of AuPd alloy nanoparticles, the high selectivity of Pd for the dehydrogenation of formic acid, and the surface plasmon resonance effect of Au. More importantly, we demonstrate that the photocatalytic processes enable re-activation of the AuPd nanoparticles that were poisoned by CO during thermal decomposition of formic acid. As such, the presented AuPd/TiO 2 nanofibers are promising materials for re-generation of H 2 under mild conditions from liquid storage carrier of hydrogen. [ABSTRACT FROM AUTHOR]

One-dimensional (1D) Pt/TiO 2 hybrid nanofibers (HNFs) with different concentrations of Pt were fabricated by a facile two-step synthesis route combining an electrospinning technique and calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) results showed that the Pt nanoparticles (NPs) with the size of 5–10 nm were well dispersed in the TiO 2 nanofibers (NFs). Further investigations from the UV–Vis diffuse reflectance (DR) and X-ray photoelectron spectroscopy (XPS) analysis revealed that some Pt ions were incorporated into the TiO 2 lattice as Pt 4+ state, which contributed to the visible light absorption of TiO 2 NFs. Meanwhile, the Pt 2+ ions existing on the surface of Pt NPs resulted in the formation of Pt–O–Ti bond at Pt NPs/TiO 2 NFs interfaces that might serve as an effective channel for improving the charge transfer. The as-electrospun Pt/TiO 2 HNFs exhibited remarkable activities for photocatalytic H 2 evolution under visible light irradiation in the presence of l -ascorbic acid as the sacrificial agent. In particular, the optimal HNFs containing 1.0 at% Pt showed the H 2 evolution rate of 2.91 μmol h −1 and apparent quantum efficiency of 0.04% at 420 nm by using only 5 mg of photocatalysts. The higher photocatalytic activity could be ascribed to the appropriate amount of Pt ions doping and excellent electron-sink effect of Pt NPs co-catalysts. [ABSTRACT FROM AUTHOR]

This report shows an increase of PAH-related microbial functional genes with PAH concentration in soils. Adaptation of microbial communities to organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) is a crucial issue. However, there is little knowledge on mechanisms ruling microbial community selection. Here, we studied microbial functional genes in soils contaminated by PAHs. We used GeoChip, an advanced functional gene array for gene analysis. Soil PAH concentrations were measured and microbial functional genes were categorized. PAH-related microbial functional genes, bph, nah, nidA, phd, dfb, and qor, were quantitatively expressed. Total microbial functional genes and PAH-related microbial functional genes were compared with PAH concentration by cluster analysis and curve-fitting analysis. We found that the average abundance of PAH-related microbial functional genes increased from 0.13 to 0.33, whereas that of total microbial functional genes decreased from 0.22 to 0.10 when PAHs concentration increased from 1.01 to 164.28 mg kg. It was also found that the classification of microbial community structure characteristics based on PAH-related microbial functional genes was closely similar to the classification based on PAHs concentration. Findings reveal that PAH stress promotes the dominance of PAH-related microbial communities. [ABSTRACT FROM AUTHOR]

Abstract: Nanofibers and nanoribbons of poly (methyl methacrylate) (PMMA)/Eu3+ ions composites with different concentration of Eu3+ ions were successfully prepared by using a simple electrospinning technique. From the results of scanning electron microscopy and energy-dispersive X-ray spectroscopy, we found that the morphology of the as-electrospun PMMA/Eu3+ ions composites could be changed from fiber to ribbon structure by adjusting the concentration of Eu3+ ions in the electrospun precursor solution. The coordination between the Eu3+ ions and PMMA molecules were investigated by Fourier transform infrared spectroscopy and differential thermal analysis. The photoluminescence (PL) properties of the as-electrospun PMMA/Eu3+ ions composites were studied in comparison to those of the Eu(NO3)3 powder. It was showed that the 5D0–7F J (J =0, 1, 2, 3, 4) emission appeared in the PL spectra of the as-electrospun PMMA/Eu3+ ions composites, whereas the 5D0–7F0 emission was completely absent in the PL spectra of Eu(NO3)3 powder due to the different local environments surrounding Eu3+ ions. It was interesting to note that the intensity ratios of the electric–dipole and magnetic–dipole transitions for the PMMA/Eu3+ ions composites could be enhanced significantly by increasing electrospinning voltage. [Copyright &y& Elsevier]

Abstract: The conserved armadillo repeat (ARM) domain of adenomatous polyposis coli (APC) protein plays an important role in the recognition of its binding partners. In this study, we report the crystal structure of APC-ARM (residues 407-775), which was determined to 2.9Å resolution. Our structure shows that the seven armadillo repeats of APC-ARM fold together into a compact domain, with Arm2 and Arm5 presenting some deviations from canonical armadillo repeats. There is a positively charged groove on the surface of APC-ARM, which might be the recognition site for APC-binding partners. Comparison of this structure with our previously reported structure of APC (407-751), together with normal mode analysis, reveals that the APC-ARM domain possesses a limited intrinsic flexibility. We propose that this intrinsic flexibility might be an inherent property of ARM domains in general. [Copyright &y& Elsevier]

Abstract: In this work, V-doped TiO2 nanofibers with different V contents have been fabricated by an electrospinning technique. The as-prepared nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy (XPS), and UV–Vis diffuse reflectance (DR) spectroscopy. The results indicated that the V4+ or V5+ ions were successfully incorporated into the crystal lattice of anatase TiO2 nanofibers. Meanwhile, the V doping could extend the visible light absorption of TiO2 nanofibers. The photocatalytic experiments indicated that the obtained V-doped TiO2 nanofibers possessed high activity for the photodegradation of organic pollutant methylene blue (MB). Especially, the 1.0 and 5.0wt.% V-doped TiO2 nanofibers exhibited the best catalytic activity under visible and ultraviolet (UV) light irradiation, respectively. Also, these nanofibers could be easily recycled without a decrease of the photocatalytic activity. [Copyright &y& Elsevier]

Abstract: Highly dispersed ZnO quantum dots (QDs) in poly(vinyl pyrrolidone) (PVP) nanofibers have been successfully prepared by electrospinning technique. The structure and optical properties were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), resonant Raman spectra, Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric and differential thermal analysis (TG–DTA), ultraviolet (UV)–vis absorption spectra, and photoluminescence (PL) spectra. In the PVP/ZnO QDs composite nanofibers, PVP molecules could effectively prevent the aggregation of ZnO QDs and passivate the surface defects of ZnO QDs. Thus, by comparing ZnO QDs, the composite nanofibers exhibited a blue-shifted band gap and enhanced ultraviolet (UV) emission. Furthermore, the composite nanofibers prepared at higher voltage showed more intense UV emission than which obtained at lower voltage, suggesting that the UV emission intensity of the composite nanofibers could be controlled by adjusting the electrospinning voltage. [Copyright &y& Elsevier]

Spr1274 is a putative choline-binding protein that is bound to the cell wall of Streptococcus pneumoniae through noncovalent interactions with the choline moieties of teichoic and lipoteichoic acids. Its function is still unknown. The crystal structure of the choline-binding domain of Spr1274 (residues 44-129) was solved at 2.38 Å resolution with three molecules in the asymmetric unit. It may provide a structural basis for functional analysis of choline-binding proteins. [ABSTRACT FROM AUTHOR]

Abstract: Thioredoxin reductase (TrxR) is a member of the pyridine nucleotide-disulfide oxidoreductase family of the flavoenzymes. It can use a dithiol-disulfide active-site to transfer reducing equivalents from NADPH to thioredoxin (Trx), via the cofactor FAD. In Saccharomyces cerevisiae, the cytoplasmic thioredoxin reductase Trr1 plays an important role in multiple cellular events under the control of transcription factor Yap1 and/or Rho5. Here we present the crystal structure of Trr1 at the resolution of 2.8 Å, the first fungal TrxR structure. Structural analysis shows it shares a very similar overall structure to Escherichia coli TrxR. However, fine comparisons indicate some distinct differences at the Trx recognition sites. These differences might be responsible to the species-specific recognition of Trx, which has been demonstrated by previous biochemical assays. [Copyright &y& Elsevier]

• Formula for critical velocity is proposed and compared with previous results. • Effects of heat release rate and blockage on variation of velocity is discussed. • Control velocity is divided into three regions according to variation trend. Longitudinal ventilation is commonly adopted to prevent toxic smoke from spreading in tunnel fires. The understanding of the parameters, such as the critical velocity and the smoke back-layering, should be of significant for the ventilation system design in tunnels. In this paper, numerical simulations are carried out to investigate the critical velocity and back-layering length in an arched tunnel with trains' blockage. A total of 51 simulated cases with varied heat release rates and longitudinal ventilated velocities are considered. The result shows that the smoke layering can be divided into two parts according to the velocity direction of the smoke movement. Based on previous theories, a formula taking the effect of tunnel cross-section and blockage into account for predicting the critical velocity is proposed, which shows good consistency with these results. According to the distribution of longitudinal velocity, it is inferred that different HRR have little effect on the reduction rate of velocity. It is also observed that the variation of dimensionless back-layering length can be divided into three regions as the dimensionless control velocity varies. Finally, the correlation between dimensionless smoke back-layering length and dimensionless control velocity in longitudinally ventilated tunnels is also proposed. [ABSTRACT FROM AUTHOR]

The accuracy and applications of synthetic aperture radar interferometry (InSAR) are severely suppressed by tropospheric error. Numerical Weather Models (NWMs) and GPS-derived tropospheric delays have been widely used to correct the tropospheric error considering their complete spatial coverage or high accuracy. However, few studies focus on the fusion of both NWMs and GPS for the tropospheric error correction. In this study, we used the Weather Research and Forecasting (WRF) to obtain NWMs with a higher spatial-temporal resolution of 3 km and 20 s from both ERAI (79 km and 6 h) and ERA5 (0.25° and 1 h). After that, we utilized the WRF Data Assimilation (WRFDA) system to assimilate the GPS ZTD into these enhanced NWMs and generate merged NWMs products. The tropospheric correction effectiveness from different NWMs products was evaluated in a case in the Pearl River Delta region of China. The results showed that all the NWMs products could correct the stratified component in the interferogram but could not mitigate the turbulence well, even after improving the spatial-temporal resolution. As for the trend component, the merged NWMs products showed obvious superiority over other products. From the statistics perspective, the stdev of the interferogram decreased further over 20% by the merged NWMs products than other products when using both ERAI and ERA5, indicating the significant effectiveness of GPS ZTD assimilation. [ABSTRACT FROM AUTHOR]

• The molecular-scale hetero-interface is achieved by assembling ultra-small HPW clusters onto g-C 3 N 4 nanosheets. • Abundant light-harvesting and catalytic sites expose on the HPW/g-C 3 N 4 hetero-interface. • The Z-scheme mechanism-enhanced photocatalytic solar-to-fuels conversion is demonstrated in the HPW/g-C 3 N 4 heterojunction. • The photocatalytic activity of HPW/g-C 3 N 4 heterojunction nanosheets is much higher than those of g-C 3 N 4 nanosheets. Rational assembly of small-sized photosensitizers onto 2D semiconductors can effectively promote the photocatalytic activity of the formed 2D heterojunction photocatalyst due to the hetero-interfacial charge-transfer process. However, the achievement of the 2D semiconductor-based heterojunction photocatalyst with the exposures of both abundant light-harvesting and catalytic sites at the hetero-interface region is still a huge challenge. Herein, we synthesized phosphotungstic acid/graphitic carbon nitride (HPW/g-C 3 N 4) heterojunction nanosheets (NSs) with the highly-dispersed distribution of ultra-small HPW clusters (1∼2 nm) by using a facile self-assembly method based on the static adsorption-deposition process. The formed molecular-scale hetero-interface between HPW clusters and g-C 3 N 4 NSs resulted in the exposure of abundant active-sites on the highly-dispersed HPW/g-C 3 N 4 hetero-interface. By combining the steady-state and transient photoluminescence spectra with the wavelength-controlled experiments, we demonstrated that the hetero-interfacial charge-transfer process occurring in the HPW/g-C 3 N 4 heterojunction NSs obeyed the Z-scheme mechanism rather than the common "type-II" heterojunction mechanism. In this way, the lifetimes of photoinduced electrons on the conduction band of g-C 3 N 4 could be prolonged for initiating the photocatalytic solar-to-fuels conversion. Upon interband excitations of both the two hetero-components in the HPW/g-C 3 N 4 heterojunction NSs, the photocatalytic activities of H 2 generation and CO 2 reduction could be enhanced by ∼2.2 and ∼6.7 times as compared to the pure g-C 3 N 4 NSs, even though the HPW component was photocatalytic-inert for either H 2 generation or CO 2 reduction upon UV–vis light irradiation. [ABSTRACT FROM AUTHOR]

• Smoke back-layering length induced by carriage fires in tunnel was revealed. • Critical ventilation velocities induced by carriage fires are quantified. • Proposed the correlation of transition velocity in ventilation tunnel. Smoke is one of the important causes of tunnel fire casualties. The critical velocity and smoke back-layering length are important parameters of smoke control in the tunnel. This paper focused on experimentally studying the characteristics of the critical control parameter (such as, critical velocity, transition velocity) and smoke back-layering length induced by carriage fire in the longitudinal ventilated tunnel, which has not been quantified in previous studies. Overall, many repeatable test conditions were involved on different fire heat release rate (HRR), the longitudinal ventilation velocity and opening sizes. It is found that, when the fire heat release rate in the tunnel is small, the critical velocity increases with the increasing heat release rate. The critical velocities will no longer change when the fire heat release rates further increases to a certain value. The relationship between dimensionless smoke back-layering length and critical velocity is piecewise function. With the longitudinal ventilation velocity increasing to a certain value, the smoke back-layering length will become not sensitive to variations with the longitudinal ventilation velocity any more. So, for this part, the new parameter called "transition velocity" implies that the dimensionless smoke back-layering length changes slowly with the dimensionless critical velocity. Then, the dimensionless correlation of smoke back-layering length and transition velocity induced by carriage fire in ventilated tunnel was proposed. [ABSTRACT FROM AUTHOR]

Kyphoplasty is an effective minimally invasive surgical treatment of osteoporotic vertebral compression fractures. Current problems associated with kyphoplasty require better injectable bone cements with improved biodegradability and osseointegrative property as an alternative to polymethyl methacrylate (PMMA) bone cement. Calcium phosphate cements (CPCs) possess superior biodegradability and osteoconductivity but inferior injectability and mechanical strengths, rendering them unsuitable for kyphoplasty applications. Our previous studies developed a corn starch-reinforced CPC with improved handling, injectable and mechanical properties, yet for kyphoplasty applications the reinforced CPC needs to have radiopacity and further enhanced mechanical strength. This work therefore developed a CPC-Starch-BaSO 4 (CSB) system and investigated the effects of radiopaque agent BaSO 4 on injectability, radiopacity, mechanical and biocompatibility properties of the system. Results showed that the addition of BaSO 4 significantly improved radiopacity and mechanical strengths of CPC cement. In addition, in vitro evaluations including apoptosis, hemolysis and endotoxin tests and in vivo evaluation of subcutaneous implantation all revealed that CSB was biocompatible. This study demonstrates that CSB could meet the clinical requirements for minimally invasive surgery and thus have great potential for kyphoplasty applications. • Radiopaque agent barium sulfate could enhance mechanical property of calcium phosphate cement. • Good biocompatibility of calcium phosphate-starch-barium sulfate composite system • Injectable, biodegradable and osseointegration of calcium phosphate composite cement [ABSTRACT FROM AUTHOR]

The tubular nanocomposite with well-dispersed distribution of small gold nanoparticles (AuNPs) assembled on the inside and outside surfaces of silica nanotubes (SNTs) was fabricated by combining the single capillary electrospinning technique and an in situreduction approach. The AuNPs/SNTs nanocomposite exhibited a good catalytic activity for reduction of 4-nitrophenol (4-NP). [ABSTRACT FROM AUTHOR]

In this paper, we introduce a modeling work on the variant reorientation in a single-crystalline Ni–Mn-Ga sample induced by a quasi-static rotating magnetic field. First, some constitutive assumptions are proposed for the variant state distribution, the effective magnetization and the elastic energy density of Ni–Mn-Ga alloys. Then, the total energy functional for a Ni–Mn-Ga sample subject to coupled magneto-mechanical loads is formulated. Through a variational approach, the governing equation system of the model can be formulated, which is composed of the magnetic and mechanical field equations, the evolution laws of some internal variables and the twin interface movement criteria. An efficient numerical scheme is adopted to solve the governing system. With the obtained numerical solutions, we first analyze the evolution properties of the configurational force on the twin interfaces. Especially, the effects of the application directions of magnetic fields on the configurational force are investigated. The influences of the different energy terms on the configurational force are also analyzed. Based on these results, we further conduct numerical simulations on the magneto-mechanical behavior of the Ni–Mn-Ga sample subject to a quasi-static rotating magnetic field. The predicted global responses of the Ni–Mn-Ga sample show good consistency with the experimental result. The configurations of the sample and the distributions of some important physical quantities in the sample during the different loading stages can also be described. Furthermore, by considering the properties of the configurational forces, the underlying mechanisms responsible for the rotating field-induced variant reorientations can be revealed. Image 1 • The response of a Ni–Mn-Ga sample subject to a rotating magnetic _eld is studied.. • The magneto-mechanical governing system is formulated through a varia-tional approach.. • The evolution properties of con_gurational forces on the twin interfaces are analyzed.. • The underlying mechanisms responsible for variant reorientations can be revealed.. • The global magneto-mechanical behavior of the Ni–Mn-Ga sample can be properly simulated.. [ABSTRACT FROM AUTHOR]

• Co-solvents such as THF and acetone prevented aggregation of Novozym 435. • Both co-solvents were beneficial for a high-yield transesterification. • Formation and dispersion of glycerin phase were affected by the co-solvents. • LLE-UNIFAC model can account for the difference between THF and acetone. To enhance the reaction rate and yield during biodiesel synthesis with Novozym 435 (an immobilized lipase), a co-solvent method was applied, after which the relationships between reaction time and reaction yield during the single-phase enzymatic transesterification of triolein and methanol in the presence of co-solvents such as tetrahydrofuran, acetone, and hexane were investigated. The addition of hexane led to inactivation of Novozym 435, whereas in the presence of acetone or tetrahydrofuran, the reaction was accelerated and the yield was higher than with a conventional solvent-free enzymatic reaction. There was a clear difference in the dispersion of Novozym 435 particles between with and without co-solvents. The co-solvents prevented particle aggregation from occurring during the reaction without co-solvent. This is the likely reason for the enhanced reaction yield in the presence of co-solvents. To better understand the difference among the co-solvents employed, we estimated phase compositions during transesterification using the LLE (liquid-liquid equilibrium)-UNIFAC (UNIversal quasichemical Functional group Activity Coefficients) model, and examined the effect of these compositions on the reaction and dispersion of the glycerin by-product phase. Using the model, we also accounted for why hexane led to inactivation by estimating the transfer free energy of methanol, glycerin, and water between the initial bulk reaction solution and the water layer on the enzyme surface. [ABSTRACT FROM AUTHOR]

Presents corrections to financial information in the above titled paper. [ABSTRACT FROM AUTHOR]

The positive matrix factorization (PMF) model is widely used for source apportionment of volatile organic compounds (VOCs). The question about how to select the proper number of factors, however, is rarely studied. In this study, an integrated method to determine the most appropriate number of sources was developed and its application was demonstrated by case study in Wuhan. The concentrations of 103 ambient volatile organic compounds (VOCs) were measured intensively using online gas chromatography/mass spectrometry (GC/MS) during spring 2014 in an urban residential area of Wuhan, China. During the measurement period, the average temperature was approximately 25 °C with very little domestic heating and cooling. The concentrations of the most abundant VOCs (ethane, ethylene, propane, acetylene, n-butane, benzene, and toluene) in Wuhan were comparable to other studies in urban areas in China and other countries. The newly developed integrated method to determine the most appropriate number of sources is in combination of a fixed minimum threshold value for the correlation coefficient, the average weighted correlation coefficient of each species, and the normalized minimum error. Seven sources were identified by using the integrated method, and they were vehicular emissions (45.4%), industrial emissions (22.5%), combustion of coal (14.7%), liquefied petroleum gas (LPG) (9.7%), industrial solvents (4.4%), and pesticides (3.3%) and refrigerants. The orientations of emission sources have been characterized taking into account the frequency of wind directions and contributions of sources in each wind direction for the measurement period. It has been concluded that the vehicle exhaust contribution is greater than 40% distributed in all directions, whereas industrial emissions are mainly attributed to the west southwest and south southwest. [ABSTRACT FROM AUTHOR]

Encapsulating organic dyes within porous solids is an efficient way to design luminescent composite materials and devices. However, for practice applications, the luminescence tuning and the stability investigation of such materials is still a challenge work. Here, a comparative in situ Raman spectra and photoluminescence (PL) spectra are employed to study the structural and optical property of both pure Rhodamine B (RHB) and samples absorbed on a kind of typical materials of institute lavoisier frameworks (MIL) under high pressure, respectively. The luminescence of RHB@MIL 53(Fe) can persist to pressures much higher than that for pure RHB. Our studies revealed that the PL emissions of RHB origin from monomeric and dimeric structures, respectively. Furthermore, our results indicated that the confining effect of MIL 53(Fe) pores inhibited the dimerization of RHB molecules under high pressure. High pressure studies on the host-guest hybrid composed of Rhodamine B molecules absorbed on MIL 53(Fe) displayed a new kind of luminescent composite material with high stability. [Display omitted] • Luminant hybrid was fabricated by encapsulating Rhodamine B molecules on MIL 53(Fe). • The luminescence of hybrid persisted to higher pressures than that for pure samples. • The MIL 53(Fe) protected RHB molecules free from dimerization under high pressure. • The molecular structure and optical property of the hybrid was tuned using pressure. [ABSTRACT FROM AUTHOR]

• Effects of curved ceiling on flame morphology in tunnels were discussed. • Flame length and fuel mass loss rate with curved ceiling in tunnel was built. • The established new models broaden the applicability of previous classic models. The model about flame length and fuel mass loss rate in this paper was developed based on the flame morphology with different longitudinal ventilation speeds when the flame was confined by the tunnel curved ceiling restriction. Secondly, after analyzing the experimental data, it was found that the air entrainment velocity was proportional to the 0.22nd power of longitudinal ventilation speed. Thirdly, the product of flame length and air entrainment velocity was proportional to the fuel mass loss rate, and the above models could better describe the characteristic evolution behaviors of flame length. Furthermore, the relation between fuel mass loss rate and longitudinal ventilation speed was established. Finally, this paper broadened the applicability of other scholars' flame tilt angle models, and found that the flame tilt angle is smaller when the flame is attached to the wall at the same wind speed. It is obvious that the above results supplement the classical tunnel-fire theory, which can be further applied to prevention and control of tunnel fire, and ultimately ensure building safety. [ABSTRACT FROM AUTHOR]

Homogenized atmospheric water vapour data are an important prerequisite for climate analysis. Compared with other techniques, GPS has an inherent homogeneity advantage, but it still requires reprocessing and homogenization to eliminate impacts of applied strategy and observation environmental changes where a selection of proper processing strategies is critical. This paper comprehensively investigates the influence of the mapping function, the elevation cut-off angle and homogenization on long-term reprocessing results, in particular for zenith tropospheric delay (ZTD) products, using GPS observations at 44 IGS (International GNSS Service) stations during 1995 to 2014. In the analysis, for the first time, we included the mapping function (the latest Vienna mapping function, VMF3) and exploited homogenized radiosonde data as a reference for ZTD trend evaluations. Our analysis shows that both site position and ZTD solutions achieved the best accuracy when using VMF3 and the 3 ∘ elevation cut-off angle. Regarding the long-term ZTD trends, homogenization reduced the trend inconsistency among different elevation cut-off angles. ZTD trend results show that the impact of mapping functions is very small, with a maximum difference of 0.19 mm yr -1. On the other hand, the discrepancy can reach 0.60 mm yr -1 using different elevation cut-off angles. Low-elevation cut-off angles (3 ∘ or 7 ∘) are suggested for the best estimates of ZTD reprocessing time series when compared to homogenized radiosonde data or ERA5 reference time series. [ABSTRACT FROM AUTHOR]

This paper experimentally investigated the internal temperature and the facade flame for compartment fires involving circular openings. A series of experiments were carried out by using a reduced-scale model which composed of a cube compartment with various circular openings and a vertical fireproofing board (used as building facade). A porous burner with propane fuel was set inside the compartment as fire source. The internal temperature profile was measured by vertical thermocouple arrays at the inner and outer corners, and the facade flame was captured by a CCD camera from a side view. This paper revealed that: (1) With the same area, maximum heat release rate inside the compartment with circular opening is larger than that with square opening. (2) For relatively larger circular openings, facade flames tend to ceiling jet flame extension. With the increasing of heat release rate, facade flame induced by ceiling jet flame extension will convert to spill fire plume. (3) A dimensionless number R , which represents the ratio of total heat release rate to internal maximum heat release rate, is proposed to distinguish spill fire plume and ceiling jet flame extension when facade flames appear at exterior. (4) A non-dimensional correlation is developed to characterize the facade flame heights for both ceiling jet flame extension and spill fire plume. These findings and results can provide fundamental knowledge for understanding compartment fire with a circular opening. [ABSTRACT FROM AUTHOR]

A recently-developed radon-based technique is modified to quantify the seasonal influences of atmospheric stability on urban emissions in Lanzhou, China, based on 11 months of observations at three sites with contrasting pollution characteristics. Near-surface concentrations of primary (CO, SO 2 , NO x ) and secondary (O 3 ) gas phase pollutants responded to changing atmospheric stability in markedly different ways in winter and summer, primarily because monsoonal fetch changes strongly influenced the distance between measurement sites and their nearest upwind pollutant sources, but also due to mean diurnal changes in mixing depth. Typically, morning peak primary pollution concentrations increased by a factor of 2–5 from the most well-mixed to stable conditions, whereas nocturnal ozone concentrations reduced with increasing stability due to surface loss processes and the progressively reduced coupling between the nocturnal boundary layer and overlying free atmosphere. The majority of pollution exceedance events (cf. China National Air Quality Standard guideline values) occurred in winter, when all measurement stations were downwind of the city's main pollution sources, and were directly attributed to morning periods and stable atmospheric conditions. In the sheltered valley region of Lanzhou, extremes of winter nocturnal stability states represented a change in mean nocturnal wind speed of only 0.25 m s −1 (from 0.6 to 0.85 m s −1 ). Daily-integrated PM 10 concentrations increased by a factor of 2 in winter from the most well-mixed to stable conditions, and were usually above guideline values at the industrial and residential sites for all atmospheric stability conditions. In summer, however, daily mean PM 10 exceedances usually only occurred at the industrial site, under stable conditions. Finally, a simple model – based on mean radon concentrations between 1900 and 0400 h – is proposed to predict haze conditions in the city prior to commencement of the peak morning commuting time. [ABSTRACT FROM AUTHOR]

In this paper, we report the energy transfer mechanism between Dy3+ ions as well as a new optical ratiometric thermometry strategy in Dy3+ doped CaWO 4 (CaWO 4 :Dy) phosphors. The optimal Dy3+ doping concentration was determined and the electric dipole-dipole interaction among Dy3+ was investigated based on the analysis of the concentration-dependence luminescent properties in CaWO 4 :Dy phosphors. The photoluminescence (PL) of two blue and two yellow emissions produced by Dy3+ transitions from the thermally coupled energy levels (TCLs) of 4I 15/2 /4F 9/2 to the 6H 15/2 ground level and 4I 13/2 metastable level, respectively, exhibited opposite PL behavior with increasing temperature. The luminescence intensity ratio (LIR) between blue and yellow emissions (B/Y) was discovered to have a quantitative relationship with temperature based on the classic thermalized population distribution of TCLs. In comparison to traditional thermometry based on the LIR of two blue emissions, the proposed new ratiometric thermometry based on the LIR of B/Y demonstrated good optical thermometry behavior with extended temperature detection range to cryogenic region, excellent absolute sensitivity, good repeatability, and high accuracy, which can also be applied to other Dy3+ doped materials such as Y 3 Al 5 O 12 and NaYF 4 phosphors using either down- or up-conversion PL of blue and yellow emissions. [ABSTRACT FROM AUTHOR]

The tropospheric model is the key model in space geodetic techniques such as Global Navigation Satellite Systems (GNSS) and Very Long Baseline Interferometry (VLBI). In this paper, we established the site-wise empirical Wuhan University Tropospheric Model (WTM) by using 10-year (2011–2020) monthly mean and 5-year (2016–2020) hourly ERA5 reanalysis data, where the Zenith Path Delay (ZPD), mapping function, and horizontal gradient as well as meteorological parameters are provided at 1583 specific space geodetic stations with additionally considering the diurnal and semi-diurnal variations. The mapping function and horizontal gradient from the WTM model were evaluated at 524 globally distributed GNSS stations during the year 2020 and compared with the latest grid-wise (1° × 1°) Global Pressure and Temperature 3 (GPT3) model. The significant improvements of the WTM model to the GPT3 model were found at the stations with terrain relief, and the maximal mapping function and horizontal gradient accuracy improvements reached 12.8 and 14.71 mm. The ZPD and mapping functions from the two models were also validated at 31 Multi-GNSS Experiment (MGEX) stations spanning the year 2020 by BeiDou Navigation Satellite System (BDS) Precise Point Positioning (PPP). The significant vertical coordinate and ZTD difference biases between the PPP schemes adopted by the two models were also found, and the largest biases reached −1.78 and 0.87 mm. [ABSTRACT FROM AUTHOR]