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A novel polymeric precursor polyborosilazane (PBSZ) for SiBN ternary ceramic fibers was successfully synthesized from trichlorosilane (HSiCl3), boron trichloride (BCl3) and hexamethyldisilazane (HDMZ) by a simple one step reaction process. The chemical structures and ceramic yield of the PBSZ precursors were investigated by NMR spectroscopy, FT-IR and TGA. The preparation of PBSZ fibers was conducted in a lab-scale melt-spinning equipment at a spinning speed of 130 m/min. SiBN ternary ceramic fibers were obtained after the non-fusible treatment and pyrolysis of PBSZ fibers in an NH3 atmosphere. The pyrolysis mechanism, high-temperature behavior and morphologies of the SiBN ternary ceramic fibers were investigated by NMR, XRD, TEM and SEM. The obtained SiBN ternary ceramic fibers had good flexibility, and possessed a tensile strength of 0.84 GPa with a diameter of ∼18 μm. Furthermore, these SiBN ceramic fibers exhibited excellent thermal stability, and maintained the amorphous state up to 1600 °C.

Different kinds of polyborosilazane(PBSZ) precursors for SiBNC ceramic fibers were synthesized by SiCl4/HSiCl3/HSiMeCl2 with BCl3 and NH3CH3 via a one-pot method, respectively. FT-IR NMR, TG, and DSC were employed to study the influence of silicon sources(SiCl4/HSiCl3/HSiMeCl2) on chemical structures and physical properties of PBSZ precursors. FT-IR and NMR results indicated that these three kinds of PBSZs have similar chemical structures, which were mainly composed of Si-N bonds and B-N bonds in the backbone(linkage through -N(CH3)- bridges). The spinning behavior of the PBSZ precursors was also investigated. The results showed that PBSZ synthesized by HSiMeCl2 had the lowest glass-transition temperature and better melt spinnability. PBSZ synthesized by SiCl4 had the highest ceramic yield. Moreover, PBSZ synthesized by HSiCl3 was the most suitable candidate to produce SiBNC ceramic fibers, and the obtained SiBNC ceramic fibers exhibited good high-temperature stability which could keep its amorphous state at 1600 °C.

Ras-related protein RalA is a member of the Ras small GTPases superfamily. Its activation plays an important role in regulating tumor initiation, invasion, migration, and metastasis. In this study, we designed a new type of RalA inhibitor containing a dihydro-α-carboline scaffold. The structurally new dihydro-α-carboline derivatives could be efficiently synthesized in good yields through a newly developed three-component [3+2+1] cyclization reaction. Evaluation of the biological activity showed that some of the dihydro-α-carboline derivatives can inhibit RalA/B and proliferative activities of NSCLC cell lines. The 4-(pyridin-3-yl)-dihydro-α-carboline compound (3 o) was found to be the most potent derivative, with IC50 values of 0.43±0.03, 0.64±0.07, 0.93±0.10, and 1.54±0.15 μM against A549, H1299, H460, and H1975 cells, respectively. Mechanism investigation suggested that 3 o inhibits the RalA/B activation of A549, down-regulates Bcl-2, stimulates cytochrome c and PARP cleavage, and induces cell apoptosis. A molecular docking study revealed that 3 o can form stable hydrogen bonds with residues of RalA. Moreover, amide-π and alkyl-π interactions also contributed to the affinity between 3 o and RalA.

Polyborosilazane synthesized from trichlorosilane (SiHCl3), boron trichloride (BCl3) and methylamine (MeNH2) is highly sensitive to moisture for hydrolysis of -NHMe unites and is easy to cross-link for dehydrogenation of Si-H, N-H, which affected the industrial scale production of SiBNC ceramic fibers. In this paper,a new nitrogen source(n-propylamine, C3H7NH2) was used instead of MeNH2 to synthesis polyborosilazane precursor. The influences of nitrogen sources on the structures and properties of SiBNC ceramic fiber precursors were investigated. As compared to SiHCl3/BCl3/CH3NH2 system, polyborosilazane precursor synthesized from the SiHCl3/BCl3/C3H7NH2 system exhibited lower crosslink density, lower sensitivity to moisture and good melt spinnability, and the obtained ceramic fibers showed higher tensile strength (1.03 GPa, an increase of about 37.3%). This synthesis route (SiHCl3/BCl3/C3H7NH2) may serve as a suitable synthetic route for a large-scale production of SiBNC ceramic fibers.

In this paper, polyborosilazane precursor was synthesied from HMDZ, HSiCl 3 , BCl 3 and CH 3 NH 2 using a multistep method. By controlling the storage conditions, parts of the polyborosilazane fibers were hydrolyzed. FT-IR, NMR, XRD, TEM and monofilament tensile strength test were employed to study the effects of hydrolysis of precursor on the structures and properties of polymer-derived SiBN ceramic fibers. FT-IR and NMR results indicate that Si-N group in PBSZ reacts with H 2 O to form Si-O-Si group. After pyrolysis reaction at 1400℃, Si-O-Si group will finally transformed into highly ordered cristobalite and β-quartz, resulting in formation of the wrinkled surface of the obtained SiBN ceramic fiber. The strip-like defects on fiber surface, according to monofilament tensile strength test, had a significant effect on mechanical property of the obtained SiBN ceramic fiber and caused no increase in fiber tensile strength of hydrolytic polyborosilazane fiber before and after pyrolytic process.

Ramie fiber, one of the strongest and oldest natural fibers, has gained much interest in adsorption of heavy metal ions in water, however, it is severely limited due to the low response rates and low adsorption capability to heavy metal ions. A novel type of carboxymethyl-functionalized porous ramie microspheres (CPRM) were prepared with a combined emulsification-evaporation method and a carboxymethylation reaction, in order to effectively remove Cd(II) in water. XPS and FTIR characterizations confirmed that the carboxyl groups were introduced onto the CPRM. The diameters of the CPRM mainly lied within the range of 8–12 μm, and the BET surface area of the CPRM was 47.6 m2/g. SEM images confirmed a porous structure was present on the CPRM surface. The CPRM obtained a high adsorption capacity of Cd(II) (173.1 mg/g) at 303 K, which was higher than most reported conventional adsorbents. The adsorption isotherms and the kinetics were in agreement with the Langmuir isotherm model and the pseudo-second-order kinetic model. The process was both endothermic and spontaneous. The CPRM could also remove Cd(II), Pb(II), Ni(II), and Zn(II) from wastewater with various efficiencies. The Cd(II)-loading CPRM could be successfully regenerated by the HCl and NaOH treatment. The CPRM show good potential for purifying wastewater.

Summary Understanding the mechanism of arsenic (As) accumulation in plants is important in reducing As's toxicity to plants and its potential risks to human health. Here, we performed a genome‐wide association study to dissect the genetic basis of the As contents of different maize tissues in Xixian, which was irrigated with As‐rich surface water, and Changge using an association population consisting of 230 representative maize inbred lines. Phenotypic data revealed a wide normal distribution and high repeatability for the As contents in maize tissues. The As concentrations in maize tissues followed the same trend in the two locations: kernels < axes

Medium-voltage, medium-frequency transformers (MFTs) are much smaller in size and weight compared to conventional line frequency transformers. MFTs are very attractive for applications where full control of the power flow and high power density are required, such as power electronic interfaces in smart grids and traction converter systems. Because of the switching loss of high-voltage semiconductor switches and the limitation of volume reduction at high frequency due to isolation requirement, MFTs are usually operated in the kHz range, which results in acoustic noise emission. In this paper, the origins of acoustic noise associated with MFTs are investigated based on vibration and acoustic measurements. The work focuses on the influence of material properties and geometric shape of the magnetic core. Based on the measurement results, nanocrystalline uncut cores with oval shape is the best solution for MFT design regarding high efficiency, high power density, and low acoustic noise emission. Finally, the low acoustic noise emission of a prototype transformer built with nanocrystalline uncut cores is verified by measurement. The winding is found to have major contribution to transformer acoustic noise if the low-magnetostrictive uncut core is used.

Voxel-based 3D convolutional neural networks (CNNs) have been applied to predict protein-ligand binding affinity. However, the memory usage and computation cost of these voxel-based approaches increase cubically with respect to spatial resolution and sometimes make volumetric CNNs intractable at higher resolutions. Therefore, it is necessary to develop memory-efficient alternatives that can accelerate the convolutional operation on 3D volumetric representations of the protein-ligand interaction. In this study, we implement a novel volumetric representation, OctSurf, to characterize the 3D molecular surface of protein binding pockets and bound ligands. The OctSurf surface representation is built based on the octree data structure, which has been widely used in computer graphics to efficiently represent and store 3D object data. Vanilla 3D-CNN approaches often divide the 3D space of objects into equal-sized voxels. In contrast, OctSurf recursively partitions the 3D space containing the protein-ligand pocket into eight subspaces called octants. Only those octants containing van der Waals surface points of protein or ligand atoms undergo the recursive subdivision process until they reach the predefined octree depth, whereas unoccupied octants are kept intact to reduce the memory cost. Resulting non-empty leaf octants approximate molecular surfaces of the protein pocket and bound ligands. These surface octants, along with their chemical and geometric features, are used as the input to 3D-CNNs. Two kinds of CNN architectures, VGG and ResNet, are applied to the OctSurf representation to predict binding affinity. The OctSurf representation consumes much less memory than the conventional voxel representation at the same resolution. By restricting the convolution operation to only octants of the smallest size, our method also alleviates the overall computational overhead of CNN. A series of experiments are performed to demonstrate the disk storage and computational efficiency of the proposed learning method. Our code is available at the following GitHub repository: https://github.uconn.edu/mldrugdiscovery/OctSurf .

Zirconium diboride (ZrB2) films were produced by liquid hybrid precursor method. Firstly, solutions of zirconium oxychloride octahydrate (ZrOCl2·8H2O), boric acid, sucrose and citric acid were mixed. Secondly, ammonium hydroxide was utilized to adjust pH and polyvinyl alcohol (PVA) acted as the aid of film formation. Next, through dip-coating and multi-step drying method, ZrB2 precursor films were fabricated. Finally, ZrB2 ceramic films were obtained via pyrolyzing the hybrid precursor at high temperature. The pyrolysis behaviors of the precursor were also investigated by XRD, SEM and pore-size distribution analysis. It was found that relatively stable structure was produced by sol-gel among the raw materials. The densification of ceramic films was reinforced as the pyrolysis temperature increased. As a result, the ZrB2 ceramic film obtained at 1600°C exhibited integrated crystal structure and uniform morphology with pores diameter of 2–5nm. Keywords: ZrB2, Precursor, Ceramic film, Pyrolysis

In this paper, we present direct mass measurements of neutron-rich $^{86}$Kr projectile fragments conducted at the HIRFL-CSR facility in Lanzhou by employing the Isochronous Mass Spectrometry (IMS) method. The new mass excesses of $^{52-54}$Sc nuclides are determined to be -40492(82), -38928(114), -34654(540) keV, which show a significant increase of binding energy compared to the reported ones in the Atomic Mass Evaluation 2012 (AME12). In particular, $^{53}$Sc and $^{54}$Sc are more bound by 0.8 MeV and 1.0 MeV, respectively. The behavior of the two neutron separation energy with neutron numbers indicates a strong sub-shell closure at neutron number $N$ = 32 in Sc isotopes., publised in Chinese Physics C Vol. 39, No. 10 (2015) 104001

We report combined magnetic susceptibility, dielectric constant, nuclear quadruple resonance (NQR) and zero-field nuclear magnetic resonance (NMR) measurements on single crystals of multiferroics CuBr$_2$. High quality of the sample is demonstrated by the sharp magnetic and magnetic-driven ferroelectric transition at $T_N=T_C\approx$ 74~K. The zero-field $^{79}$Br and $^{81}$Br NMR are resolved below $T_N$. The spin-lattice relaxation rates reveal charge fluctuations when cooled below 60~K. Evidences of an increase of NMR linewidth, a reduction of dielectric constant, and an increase of magnetic susceptibility are also seen at low temperatures. These data suggest an emergent instability which competes with the spiral magnetic ordering and the ferroelectricity. Candidate mechanisms are discussed based on the quasi-one-dimensional (1D) nature of the magnetic system.

Isochronous mass spectrometry has been applied to neutron-deficient $^{58}\mathrm{Ni}$ projectile fragments at the HIRFL-CSR facility in Lanzhou, China. Masses of a series of short-lived ${T}_{z}=\ensuremath{-}3/2$ nuclides including $^{41}\mathrm{Ti}$, $^{45}\mathrm{Cr}$, $^{49}\mathrm{Fe}$, and $^{53}\mathrm{Ni}$ have been measured with a precision of 20--40 keV. The new data enable us to test for the first time the isobaric multiplet mass equation (IMME) in $fp$-shell nuclei. We observe that the IMME is inconsistent with the generally accepted quadratic form for the $A=53$, $T=3/2$ quartet. We perform full space shell model calculations and compare them with the new experimental results.

Mass excesses of short-lived $A=2Z\ensuremath{-}1$ nuclei $^{63}\mathrm{Ge}$, $^{65}\mathrm{As}$, $^{67}\mathrm{Se}$, and $^{71}\mathrm{Kr}$ have been directly measured to be $\ensuremath{-}46\text{ }921(37)$, $\ensuremath{-}46\text{ }937(85)$, $\ensuremath{-}46\text{ }580(67)$, and $\ensuremath{-}46\text{ }320(141)\text{ }\text{ }\mathrm{keV}$, respectively. The deduced proton separation energy of $\ensuremath{-}90(85)\text{ }\text{ }\mathrm{keV}$ for $^{65}\mathrm{As}$ shows that this nucleus is only slightly proton unbound. X-ray burst model calculations with the new mass excess of $^{65}\mathrm{As}$ suggest that the majority of the reaction flow passes through $^{64}\mathrm{Ge}$ via proton capture, indicating that $^{64}\mathrm{Ge}$ is not a significant $rp$-process waiting point.

Direct mass measurements of 78 Kr projectile fragments have been performed in the recently commissioned storage ring CSRe employing the isochronous mass spectrometry method. A new data-analysis technique has been developed to correct the drifts in the revolution frequencies caused by instabilities of the magnetic fields in the CSRe, thus yielding a mass resolving power of R = m / Δ m ≈ 1.7 × 10 5 (sigma). Masses for 45 V, 47 Cr, 49 Mn and 51 Fe nuclei are determined with a relative mass precision of δ m / m ≈ 2 × 10 − 7 (sigma) which is an improvement by a factor of ∼ 2 compared to the literature values.

Low-temperature oxidative degradation of formaldehyde (HCHO) using non-noble metal catalysts is challenging. Herein, novel manganese dioxide (MnO2)/N-doped carbon nanotubes (NCNT) composites were prepared with varying MnO2 content. The surface properties and morphologies were analyzed using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM). Comparing with MnO2/carbon nanotubes (CNTs) catalyst, the 40% MnO2 /NCNT exhibited much better activity and selectivity for HCHO oxidation, mineralizing 95% of HCHO (at 100 ppm) into CO2 at 30 degrees C at a gas hourly space velocity (GHSV) of 30,000 mL h(-1) g(-1). Density functional theory (DFT) calculation was used to analyze the difference in the catalytic activity of MnO2 with CNTs and NCNT carrier. It was confirmed that the oxygen on NCNT was more active than CNTs, which facilitated the regeneration of MnO2. This resulted in remarkably boosted activity for HCHO oxidation. The present work thus exploited an inexpensive approach to enhance the catalytic activity of transition metal oxides via depositing them on a suitable support. Refereed/Peer-reviewed