On the rational cuspidal subgroup and the rational torsion points of

For two distinct prime numbers , , we compute the rational cuspidal subgroup of and determine the -primary part of the rational torsion subgroup of the old subvariety of for most primes . Some results of Berkovic on the nontriviality of the Mordell-Weil group of some Eisenstein factors of are also refined.

     

Implantable Vascularized Liver Chip for Cross‐Validation of Disease Treatment with Animal Model

Artificial liver models have been extensively developed for pathological modeling and toxicological studies. However, the prediction of existing in vitro liver models rarely corresponds to what is consequently observed in vivo owing to the structural and functional complexity of the liver. Here, a new liver model designed to enable the implantation and maintenance of liver buds in perfusable 3D hydrogels where a microvascular network develops within a 200 µm diffusion limit is developed. This system replicates inflammation, lipid accumulation, and fibrosis during the progressive processes of nonalcoholic fatty liver disease, in which this model predicted the results from a mouse model. This model reveals that a hepatic steatosis‐reducing drug restored mitochondrial activities with significant reduction of inflammation, oxidative stress, and lipid accumulation. This liver model is not only highly predictive but also scalable and easy to apply to high‐throughput drug screening and implantation studies, suggesting a promising alternative to animal models.     

Concurrent Synthesis of High‐Performance Monolayer Transition Metal Disulfides

To date, the chemical vapor deposition (CVD) approach has been widely used for the growth of transition metal dichalcogenides (TMDs). However, the reported CVD methods to synthesize TMDs cannot be used to grow more than one type of TMDs. This work reports a promising CVD technique to concurrently synthesize multiple monolayer transition metal disulfides once. The optoelectrical characterization and high‐resolution transmission electron microscopy show the high quality of monolayer crystals, and, more importantly, there is no mixing between different precursors during the growth process, which has been investigated by considering the gas flow dynamics and concentration distribution of precursors in our setup. This strategy indicates the promising future for the batch production of 2D materials and the concurrent synthesis techniques in standard state‐of‐the‐art complementary metal‐oxide‐semiconductor (CMOS) fabrication technology.     

Fast and Accurate Visual Place Recognition Using Street‐View Images

A fast and accurate building‐level visual place recognition method built on an image‐retrieval scheme using street‐view images is proposed. Reference images generated from street‐view images usually depict multiple buildings and confusing regions, such as roads, sky, and vehicles, which degrades retrieval accuracy and causes matching ambiguity. The proposed practical database refinement method uses informative reference image and keypoint selection. For database refinement, the method uses a spatial layout of the buildings in the reference image, specifically a building‐identification mask image, which is obtained from a prebuilt three‐dimensional model of the site. A global‐positioning‐system‐aware retrieval structure is incorporated in it. To evaluate the method, we constructed a dataset over an area of 0.26 km². It was comprised of 38,700 reference images and corresponding building‐identification mask images. The proposed method removed 25% of the database images using informative reference image selection. It achieved 85.6% recall of the top five candidates in 1.25 s of full processing. The method thus achieved high accuracy at a low computational complexity.     

Ferromagnetic interaction in mu1,3-cyanamido-derived copper(II) cryptates

The reaction of dinuclear copper(II) cryptates with calcium cyanamide, CaNCN, and sodium dicyanamide, Na[N(CN)(2)] results in dinuclear compounds of formulae [Cu(2)(HNCN)(R3Bm)](ClO(4))(3) (1), [Cu(2)(dca)(R3Bm)](ClO(4))(3)4H(2)O (2), and [Cu(2)(NCNCONH(2))(R3Bm)](CF(3)SO(3))(3) (3), in which R3Bm=N[(CH(2))(2)NHCH(2)(C(6)H(4)-m)CH(2)NH(CH(2))(2)](3)N and dca=dicyanamido ligand (NCNCN(-)). The X-ray diffraction analysis reveals for both 1 and 3 a dinuclear entity in which the copper atoms are bridged by means of the -NCN- unit. The molar magnetic susceptibility measurements of 1-3 in the 2-300 K range indicate ferromagnetic coupling. The calculated J values, by using theoretical methods based on density functional theory (DFT) are in excellent agreement with the experimental data. Catalytic hydration of a nitrile to an amide functional group is assumed responsible for the formation of 3 from a mu(1,3)-dicyanamido ligand.     

Investigation of the scanning tunneling microscopy image, the stacking pattern, and the bias-voltage-dependent structural instability of 1,10'-phenanthroline molecules adsorbed on Au(111) in terms of electronic structure calculations

A self-assembled monolayer of 1,10'-phenanthroline (phen) molecules on Au(111) was found to undergo a structural phase transition when the bias voltage is switched in scanning tunneling microscopy (STM) experiments (Phys. Rev. Lett. 1995, 75, 2376; Surf. Sci. 1997, 389, 19). The nature of two bright spots representing each phen molecule in the high-resolution STM images of phen molecules on Au(111) was identified by calculating the partial density plots for a monolayer of phen molecules adsorbed on Au(111) with tight-binding electronic structure calculations. The stacking pattern of chains of phen molecules on Au(111) was explained by studying the intermolecular interactions between phen molecules on the basis of first-principles electronic structure calculations for a phen dimer, (phen)(2). The structural instability of phen molecule arrangement caused by the bias-voltage switch was probed by estimating the adsorbate-surface interaction energy with the point-charge approximation for Au(111).     

Dynamic hollow fiber-supported headspace liquid-phase microextraction

With the increasing concern over deteriorating environmental quality, the analysis of organic pollutants in air, water, and soil has become critically important. The development of simple, efficient, and inexpensive analytical sample pretreatment is crucial for monitoring and evaluating the environment. In this work, a dynamic hollow-fiber supported headspace liquid-phase microextraction (DHF-HS-LPME) approach was developed. In dynamic LPME, the extracting solvent is held within a hollow fiber, affixed to a syringe needle and immersed in the sample solution, and is moved to-and-fro by using a programmable syringe pump. The movement facilitates mass transfer from the sample to the solvent. Here, a similar approach was adopted, except that extraction was from the headspace rather than by direct immersion. Analysis of the extract was carried out by gas chromatography-mass spectrometry. The effect of sampling temperature, water, salt, dwelling time were investigated. Results indicated that this novel headspace microextraction method gave good analyte-enrichment factors, linear range, limits of detection and repeatability, all of which were evaluated by extracting PAHs from soil samples. This technique represents an inexpensive, convenient, fast and simple sample preparation of this class of semi-volatile organic compounds.     

Emission Characteristics of Jet Configurations for Jet-Boosted Glow Discharge Atomic Emission Spectrometry

Comparisons of emission characteristics and analytical performance have been made between three types of jet configuration. These include cone-jet configuration, six-jet configuration, and cylinder-jet configuration. The cone-jet configuration shows the highest emission intensity among all jet configurations. Regardless of the jet configuration, the Cu II 224.70 nm emission line was found to be the most dominant of all Cu emission lines. The intensity ratios of the resonance line Cu I 324.75 to a nonresonance line Cu I 282.44 nm was 1.3 for the six-jet configuration, 2.3 for the cylinder jet, and 2.8 for the cone jet. This may indicate that self-absorption was significant in six-jet configuration. The effects of main and auxiliary gas flow rates on the emission characteristics for the cone jet configuration were also investigated. The intensity of Cu I at 324.75 and 327.40 nm decreases about 30% when the gas flow rate increased from 0 to 150 ml/min, while the intensities of Cu II 224.70 nm and the UV–Visible Cu I 510.55-, 515.32-, and 521.82-nm lines increased by a factor of 2 to 3. The decrease in intensity of the resonance line relative to the Cu II and Cu I green lines may be caused by self-absorption. The cone-jet and six-jet configurations show comparable values of precision, linearity, and detection limits, while the cylinder-jet configuration provides the worst analytical performance among three types of jet configurations. The linearity of the calibration curve was the worst in the six-jet configuration due to self-absorption.     

Substituted metal carbonyls XXIII . Syntheses of unicoordinated diphosphine complexes of Cr and Mo and their entry into heterobimetallics MM′(CO)10(μ-P-P) [M, M′= Cr, Mo, W; P---P = Ph2P(CH2)nPPh2, n = 2–4] as metalloligands

A series of pentacarbonyl complexes of chromium and molybdenum with unicoordinated-diphosphines, M(CO)₅(η¹-P-P) (P-P = dppe, dppp, dppb) has been prepared by amine oxide-induced phosphine substitution of the binary carbonyls. The basicity of the pendant phosphine groups was demonstrated by their ready conversion to the diphosphine-bridged heterobimetallic complexes (OC)₅M(μ-P-P)M′(CO)₅ (M, M′= Cr, Mo, W; M ≠ M′) in the presence of MCO)₅(CH₃CN). The complexes were characterized by IR and NMR (¹H and ³¹P-{¹H}) spectroscopy.     

Rapid Raman mapping of a fulgurite

A fulgurite is a naturally occurring glass formed when lightning hits sand, rock, or soil. The formation of fulgurites is accompanied by mineralogical and sometimes compositional changes, and may record information about the environment in which they were formed. A previous investigation using Raman point spectroscopy discovered the presence of anatase, a low-temperature polymorph of TiO₂, and polyaromatic hydrocarbons within a fulgurite. These findings indicate that there were regions within the sample that were not subjected to temperatures of 2,000 K or more that the matrix is reported to attain when struck by lightning. This paper seeks to expand the previous research by utilizing the capabilities of a new Raman spectroscopic technological development that enables rapid mapping. The entire surface area of a cross-sectioned fulgurite (∼40 mm × 23 mm) sample was mapped allowing several regions of polyaromatic hydrocarbons and anatase to be located. Furthermore, shocked quartz was found within the boundary regions of the fulgurite, and is proposed to have resulted from contact with vaporized material during the lightning strike. Shocked quartz is typically indicative of extraterrestrial impact, yet its discovery here suggests that its formation is not exclusive to the impact process.