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This work reports a super high-frequency (SHF) bulk acoustic wave (BAW) resonator, utilizing a single crystal aluminum scandium (Sc) nitride (Al $_{{1}-{x}}$ ScxN) piezoelectric film with 30% Sc concentration, fabricated by a novel cavity-embedded process and exhibiting an effective electromechanical coupling coefficient ( ${k} ^{{2}}_{\text {eff}}$ ) of 21% for Al $_{{1}-{x}}$ ScxN BAW resonators operating above 4 GHz. A novel two-step method was proposed to obtain high crystalline quality Al0.7Sc0.3N films, characterized by the full-width at half-maximum (FWHM) of 0.73° in (0002) X-ray diffraction (XRD) and the absence of abnormal oriented grains (AOGs). The resonator unit, designed without lateral airgaps, doubles the thermal conductivity and significantly reduces the maximum stress of the suspended film stack by an order of magnitude. The novel cavity-embedded fabrication process combined with the lateral-airgapless device design offers excellent mechanical stability and manufacturing feasibility of BAW filters. The fabricated 4.39-GHz single crystal Al0.7Sc0.3N BAW resonators exhibit exceptional ${k} ^{{2}}_{\text {eff}}$ , leveraging the high crystallinity of Al0.7Sc0.3N film, surface-intact device design, and feasible fabrication process. Additionally, a 4.43-GHz ladder-typed filter was demonstrated with a −3-dB fractional bandwidth of 9.0%. This work paves the path toward the development of the next-generation high-frequency and wideband acoustic filters for emerging 5G and Wi-Fi wireless communications.

The characteristic analysis of car-following behavior in different scenarios is important for studying microscopic traffic flow models. This study first used roadside light detecting and ranging (LiDAR) to collect traffic 3-D point cloud data to reveal the driving behavior characteristics of localized urban intersections. The background subtraction method is used to filter out the background objects. The density-based spatial clustering of applications with noise algorithm detects and identifies vehicle objects. The traffic target tracking method based on historical frame data fusion obtained the vehicle trajectory. Second, this article designed a method to extract high-resolution microscopic traffic information. This method constructs the boundary box model of traffic objects by finding fixed point features. Then, the speed, distance, and other information are calculated through the coordinate relationship of vehicle position. Finally, the velocity and gap distance characteristics are analyzed in car-following behavior. This study found a significant correlation between the speed of the front and rear vehicles in the car-following process. A linear function can effectively fit the relationship between speed and gap distance. This article also verifies the asymmetric characteristics of driving behavior under acceleration and deceleration conditions at urban intersections.

This brief presents the development of an ${E}$ -band (71–76 GHz) continuous wave (CW) space traveling wave tube (TWT) with substantial performance improvement. This tube was designed using modified folded waveguide (FWG) and dynamic phase velocity tapering (DVT) circuits, together with four-stage depressed collectors made of graphite. Based on calculation and simulation data, a prototype ${E}$ -band space TWT was fabricated, with the testing conducted at a relatively lower beam voltage of 14.1 kV and current of 70.3 mA. The test results show the prototype is capable of providing output power up to 106 W, gain of 41 dB and overall efficiency of 52%, at 71–76 GHz. It is also found within the 5 GHz bandwidth, the electronic efficiency is over 10.6%, while a maximum saturated output power reaches 122 W, with a corresponding overall efficiency of 55%. Given the above data, attained at the relatively lowered operating voltage and current, it is believed the overall performance of this ${E}$ -band TWT exhibits a substantial improvement as compared to those of the reported similar tubes.

This letter presents a high-power (> 1 kW) broadband gyrotron traveling wave amplifier (gyro-TWA) based on a five-fold (5F) helically corrugated interaction region (HCIR) that operates at the frequency range of 254-280 GHz. The 5F HCIR was manufactured and its measured dispersion characteristics matched very well both with the theoretical predictions and simulated results. The third harmonic cyclotron mode of a 60 keV, 0.75 A, axis-encircling electron beam could be used to resonantly interact with a traveling TE31-like eigenwave in the 5F HCIR to achieve a broadband amplification. The 3-D particle-in-cell simulations predicted a saturated output power and gain of ~1.5 kW and 39.7 dB respectively, with a 3-dB bandwidth of ~26 GHz (~10% relative bandwidth) driven by a 0.16 W input signal.

A novel device structure is proposed for total ionizing dose (TID) hardening, which combines H-gated MOSFETs with void-embedded silicon on insulator (VESOI) substrate. At total doses up to 3Mrad(Si), the shift of threshold voltage ( $\Delta {V}_{\text {th}}{)}$ is only about 60mV/dec and non-discernable changes in off-state current ( ${I}_{\text {off}}{)}$ were observed. Furthermore, TCAD simulation results indicate that nearly all leakage paths caused by radiation-induced trap charges are effectively eliminated in our H-gated VESOI MOSFETs. This device structure also exhibits high tolerance for variation in void height under different fabrication conditions. The exceptional radiation immunity and compatibility with planar CMOS processes make it a competitive option for anti-irradiation applications.

Welding is a key missing manufacturing technique in graphene science. Due to the infusibility and insolubility, reliable welding of macroscopic graphene materials is impossible using current diffusion-bonding methods. This work reports a pulsed laser welding (PLW) strategy allowing for directly and rapidly joining macroscopic 3D porous graphene materials under ambient conditions. Central to the concept is introducing a laser-induced graphene solder converted from a designed unique precursor to promote joining. The solder shows an electrical conductivity of 6700 S m−1and a mechanical strength of 7.3 MPa, over those of most previously reported porous graphene materials. Additionally, the PLW technique enables the formation of high-quality welded junctions, ensuring the structural integrity of weldments. The welding mechanism is further revealed, and two types of connections exist between solder and base structures, i.e., intermolecular force and covalent bonding. Finally, an array of complex 3D graphene architectures, including lateral heterostructures, Janus structures, and 3D patterned geometries, are fabricated through material joining, highlighting the potential of PLW to be a versatile approach for multi-level assembly and heterogeneous integration. This work brings graphene into the laser welding club and paves the way for the future exploration of the exciting opportunities inherent in material integration and repair.

Two types of proton channels are reconstructed in the SPEEK-based hybrid membrane via modified Zr-MOFs, which effectively break through the trade-off between proton conductivity and ion selectivity of PEM for VFB applications.

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Bee pollen has gained popularity among consumers due to its rich nutritional value. However, the stiff pollen wall severely limits the absorption and biological efficacy of the nutrients in bee pollen. In this study, deep enzymatic hydrolysis (ultrasonication + cellulase, pectinase, and Protamex™) was used to break the wall and improve the utilization of bee pollen nutrients. This treatment resulted in a 64.40% reduction in particle size and a 139.72% increase in specific surface area. Soluble sugar, total phenols, total flavonoids, and soluble protein increased by 20.14%, 92.78%, 103.21%, and 37.80%, respectively. Proteomics and Metabolomic analysis revealed a significant increase in the content of 1447 peptides and 44 compounds in the bee pollen post-multi-enzyme deep enzymatic hydrolysis compared to the untreated control group. These findings indicate that the application of ultrasonication + three enzymes, as a multi-enzyme composite deep enzyme wall breaking method, can significantly improve the release rate of bee pollen nutrients and generate a multitude of small molecule polypeptides, thereby enhancing their potential bioactivity. This study provides technical support and theoretical reference for deeply processing bee pollen and developing high-value products.

The most widely adopted method for diagnosing respiratory infectious diseases is to conduct polymerase chain reaction (PCR) assays on patients’ respiratory specimens, which are collected through either nasal or oropharyngeal swabs. The manual swab sampling process poses a high risk to the examiner and may cause false-negative results owing to improper sampling. In this paper, we propose a pneumatically actuated soft end-effector specifically designed to achieve all of the tasks involved in swab sampling. The soft end-effector utilizes circumferential instability to ensure grasping stability, and exhibits several key properties, including high load-to-weight ratio, error tolerance, and variable swab-tip stiffness, leading to successful automatic robotic oropharyngeal swab sampling, from loosening and tightening the transport medium tube cap, holding the swab, and conducting sampling, to snapping off the swab tail and sterilizing itself. Using an industrial collaborative robotic arm, we integrated the soft end-effector, force sensor, camera, lights, and remote-control stick, and developed a robotic oropharyngeal swab sampling system. Using this swab sampling system, we conducted oropharyngeal swab-sampling tests on 20 volunteers. Our Digital PCR assay results (RNase P RNA gene absolute copy numbers for the samples) revealed that our system successfully collected sufficient numbers of cells from the pharyngeal wall for respiratory disease diagnosis. In summary, we have developed a pharyngeal swab-sampling system based on an “enveloping” soft actuator, studied the sampling process, and implemented whole-process robotic oropharyngeal swab-sampling.

Chestnut plants (Castanea) are important nut fruit trees worldwide. However, little is known regarding the genetic relationship and evolutionary history of different species within the genus. How modern chestnut plants have developed local adaptation to various climates remains a mystery. The genomic data showed that Castanea henryifirst diverged in the Oligocene ~31.56 million years ago, followed by Castanea mollissima,and the divergence between Castanea seguiniiand Castanea crenataoccurred in the mid-Miocene. Over the last 5 million years, the population of chestnut plants has continued to decline. A combination of selective sweep and environmental association studies was applied to investigate the genomic basis of chestnut adaptation to different climates. Twenty-two candidate genes were associated with temperature and precipitation.We also revealed the molecular mechanism by which CmTOE1interacts with CmZFP8and CmGIS3to promote the formation of non-glandular trichomes for adaptation to low temperature and high altitudes. We found a significant expansion of CER1genes in Chinese chestnut (C. mollissima) and verified the CmERF48regulation of CmCER1.6adaptation to drought environments. These results shed light on the East Asian chestnut plants as a monophyletic group that had completed interspecific differentiation in the Miocene, and provided candidate genes for future studies on adaptation to climate change in nut trees.

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To achieve high solar energy utilization efficiency, photothermal materials with broadband absorption of sunlight and high conversion efficiency are becoming a fast-growing research focus. Inspired by the forest structure with efficient sunlight utilization, we designed and fabricated a graphene film consisting of densely arranged porous graphene though laser scribing on polybenzoxazine resin (poly(Ph-ddm)). This hierarchical structure significantly reduced the light reflection of graphene as a 2D material. With a combination of advanced photothermal conversion properties of graphene, the 3D structured graphene film, named forest-like laser-induced graphene (forest-like LIG), was endowed with a very high light absorption of 99.0% over the whole wavelength range of sunlight as well as advanced light-to-heat conversion performance (reaching up to 87.7 °C within 30 s under the illumination of simulated sunlight and showing an equilibrium temperature of 90.7 ± 0.4 °C). As a further benefit of its superhydrophobicity, a photothermal actuator with quick actuated response and high motion velocity, as well as a solar-driven interfacial desalination membrane with durable salt-rejecting properties and high solar evaporation efficiencies, was demonstrated.

Although China remains consistent in its stance and practice in unilateral sanctions episodes, its ‘decade of sanctions’ has witnessed some subtle changes—in particular, its endeavour to build a rule-of-law-based unilateral sanctions regime. Both international law and the domestic law of China provide for its unilateral sanctions. It is within the discretion of China to take unilateral sanctions as long as it is not against its obligation under the applicable international law, but its domestic law shows a certain level of insufficiency. The administrative nature of unilateral sanctions decides the core parameter of due process for a rule-of-law-based unilateral sanctions regime, which has its boundaries: the limit of law as a regulatory regime for unilateral sanctions as political instrument and the limit of domestic jurisdiction in terms of extraterritorial application. To upgrade the unilateral sanctions regime according to its own concept of rule of law in foreign relations, China needs to improve the compatibility among current laws and to provide proper remedies.

The murine lower incisor ectodermal organ contains a single epithelial stem cell (SC) niche that provides epithelial progenitor cells to the continuously growing rodent incisor. The dental stem cell niche gives rise to several cell types and we demonstrate that the miR‐200family regulates these cell fates. The miR‐200family is highly enriched in the differentiated dental epithelium and absent in the stem cell niche. In this study, we inhibited the miR‐200family in developing murine embryos using new technology, resulting in an expanded epithelial stem cell niche and lack of cell differentiation. Inhibition of individual miRs within the miR‐200cluster resulted in differential developmental and cell morphology defects. miR‐200inhibition increased the expression of dental epithelial stem cell markers, expanded the stem cell niche and decreased progenitor cell differentiation. RNA‐seq. identified miR‐200regulatory pathways involved in cell differentiation and compartmentalization of the stem cell niche. The miR‐200family regulates signaling pathways required for cell differentiation and cell cycle progression. The inhibition of miR‐200decreased the size of the lower incisor due to increased autophagy and cell death. New miR‐200targets demonstrate gene networks and pathways controlling cell differentiation and maintenance of the stem cell niche. This is the first report demonstrating how the miR‐200family is required for in vivo progenitor cell proliferation and differentiation. The LaCL stem cell niche does not express miR‐200, which regulates Sox2 expression. Progenitor cells exiting the stem cell niche start expressing miR‐200 to promote differentiation and the specification of cell fates for mature tooth development. miR‐200 therefore acts to compartmentalize the stem cell niche

Molybdenum disulfide (MoS2) has substantial application prospects in the field of electronic devices. The fabrication of devices of excellent quality based on MoS2films is an important research direction. In this study, based on the atomic layer deposition technique, large-area MoS2films were grown, and top-gate MoS2-based field-effect transistor arrays were fabricated on four substrates (AlN, GaN, sapphire, and SiO2). It was found that the interface defects that were introduced by lattice mismatch and roughness of the growth substrate could cause an exponential (102) drop in mobility. Because of the small lattice mismatch and excellent surface quality, transistors on the AlN substrate have shown an enhanced mobility (10.45 cm2V–1s–1) compared to transistors on the other substrates. This study proves that the AlN substrate is a superior substrate for large-area and high-performance MoS2film synthesis. This result can also be applied in higher-level microelectronic systems, such as in digital logic circuit design.

The creative integration of sp-hybridized carbon atoms into artificial carbon graphdiyne has led to graphdiyne with superior properties in terms of uniformly distributed pores, ambipolar carrier transport, natural bandgap, and broadband absorption. Consequently, graphdiyne, regarded as a promising carbon material, has garnered particular attention in light–matter interactions. Light–matter interactions play an important role in optical information technology and meet the increasing demand for various energy sources. Herein, the status and challenges in nonlinear photonic and optoelectronic applications of graphdiyne, which are still in the infancy stage, are summarized. Furthermore, the bottleneck and perspective of graphdiyne in these aspects are discussed. It is therefore anticipated that this review could promote the development of graphdiyne in photonic and optoelectronic fields.

In this study, efforts were made to prepare a porous aromatic framework (PAF) with build-in magnetic nanoparticles (Fe3O4-PAF) for use as an efficient adsorbent for the removal of organic pollutants from water. The Fe3O4-PAF showed good handleability and could be recovered easily by magnetic separation. As a proof of concept, the adsorption properties of Fe3O4-PAF were investigated to remove 2,4-dichlorophenol (2,4-DCP) and bisphenol A (BPA) from water. The Fe3O4- PAF showed a fast adsorption rate, high adsorption efficiency and high adsorption capacities. It adsorbed 2,4-DCP (0.1 mmol L−1) and BPA (0.1 mmol L−1) with pseudo-second-order rate constant (k2) of 2.1 and 3.54 g mg−1min−1, respectively. According to the Langmuir isotherm model, the maximum adsorption capacities of 2,4-DCP and BPA onto Fe3O4-PAF were calculated to be 234.74 and 233.65 mg g−1, respectively. The Fe3O4-PAF also featured good tolerance to harsh conditions, facilitating its application in a real water environment. It could be regenerated easily and reused multiple times without obvious loss of efficiency. In summary, this study provides a general and effective way to improve the handleability of PAFs and expands the practical application of PAF-based materials.

High-precision aspheric negative plastic lenses are widely used in optical systems owing to their excellent performance and ease of high-efficiency manufacturing. The imaging performance of the lens is difficult to control, because it is unable to perform optical measurements directly and is sensitive to manufacturing processing meanwhile. Generally, the imaging performance is guaranteed by a strict control of geometrical deviation, such as Peak-to-Valley (PV) and Root-Mean-Square (RMS). In this study, an optical ray-tracing algorithm with the measured geometrical deviation data is proposed to perform an imaging performance analysis correlated with geometrical deviation for the injection molded high-precision aspheric negative plastic lens. Taguchi experiments are applied to investigating the effect of processing parameters. The geometrical deviation of the convex surface is found to be an order of magnitude greater than that of the concave surface. The geometrical dimension of the concave surface is mainly determined by the machining precision of the mold cavity surface, whereas the convex surface dimension is mainly affected by the lens shrinkage. However, the imaging performance has a nonlinear correlation with the geometrical deviation. Modulation Transfer Function (MTF) and Spot Diagram are equivalently affected by the concave and convex geometrical deviations, and depend on the object field height. The effect of processing parameters on geometrical deviation and imaging performance is uncorrelated. Thus, the imaging performance should be simultaneously considered as a criterion as well as the geometrical deviation in the optimization of aspheric negative lens injection molding processing. The imaging performance prediction using an optical ray-tracing algorithm with the measured geometrical deviation data is instrumental to optimize the manufacturing processing.

MoS2, as a typical representative of two-dimensional semiconductors, has been explored extensively in applications of optoelectronic devices because of its adjustable bandgap. However, to date, the performance of the fabricated photodetectors has been very sensitive to the surrounding environment owing to the large surface-to-volume ratio. In this work, we report on large-scale, high-performance monolayer MoS2photodetectors covered with a 3-nm Al2O3layer grown by atomic layer deposition. In comparison with the device without the Al2O3stress liner, both the photocurrent and responsivity are improved by over 10 times under 460-nm light illumination, which is due to the tensile strain induced by the Al2O3layer. Further characterization demonstrated state-of-the-art performance of the device with a responsivity of 16.103 A W−1, gain of 191.80, NEP of 7.96 × 10−15W Hz−1/2, and detectivity of 2.73 × 1010Jones. Meanwhile, the response rise time of the photodetector also reduced greatly because of the increased electron mobility and reduced surface defects due to the Al2O3stress liner. Our results demonstrate the potential application of large-scale strained monolayer MoS2photodetectors in next-generation imaging systems.

The reactions of Ge, Sn, Pb, Sb, Bi, and Te atoms with silane molecules were studied using matrix-isolation Fourier transform infrared spectroscopy and density functional theoretical (DFT) calculations. All metals generate the inserted complexes HM-SiH3, which were stabilized in an argon matrix, while H2MSiH2and H3MSiH were not observed. DFT and CCSD(T) calculations show the insertion complex HM-SiH3is the most stable isomer with a near right angle H–M–Si moiety. However, silydene complexes H2MSiH2(M = C, Si) were calculated and identified as the most stable complexes with the lighter elements. The bonding difference is mainly due to relativistic effects, which is that for heavier metal atoms valence s and p orbitals have a lower tendency to form hybrid orbitals.

This study assessed the effects of dietary intervention of Triadica cochinchinensishoney (TH) on blood lipid profiles, hepatic lipid metabolism, and the gut microbiota in mice undergoing natural aging. All mice were fed a standard diet, supplemented with TH at a dosage of 5 g/kg BW over nine months until the mice were 18 months old. The findings of the study indicated that administering TH significantly decreased the levels of circulating triglycerides (TG), cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C). Additionally, TH imparted hepatoprotective effects by mitigating liver damage, decreasing the activity of antioxidative enzymes, and suppressing the expression of inflammatory markers, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). The lipidomic study revealed that administering TH considerably altered lipid synthesis and metabolism in the aging liver. These changes were characterized by an increase in the levels of 56 lipids and a reduction in the levels of 52 lipids, primarily consisting of TGs. Additionally, TH consumption significantly modified the structure and composition of the gut microbiota. The intervention restored the reduced abundance of Akkermansia in elderly mice and increased the relative abundances of Bacteroidaceae, Sutterellaceae, Burkholderiales, and Gammaproteobacteria. These findings highlighted the high activity of TH and its beneficial effect on aging, providing strong empirical support for the application of TH in the fields of nutrition and pharmaceuticals.

With the increasing integration of electronic devices, efficient thermal management is urgently required. Herein, 3D graphene/Cu-based dual networks were developed for highly thermal conductive epoxy (Cu@hLIG/EP) composites. Using the honeycomb-like porous laser-induced graphene (hLIG) as 3D skeleton, the Cu layer was introduced by electroless plating. The Cu@hLIG/EP composite showed a high thermal conductivity up to 16.4 W m−1 K−1, which was almost 63 times that of neat EP and 6 times that of hLIG/EP composite with similar filler loading. This increase was attributed to the pre-constructed 3D network, phonon-electron dual thermal transfer channels and reduced phonon mismatch in composites. Furthermore, by using the reprocessable EP resin, the designability of thermal conductive composites was greatly enhanced, where layered composites could be easily fabricated by the simple stacking strategy. The material/process developed demonstrates wide promise in thermal management applications.

The boron–transition-metal triple-bond complexes FB≡MF2(M= Ir, Os, Re, W, Ta) were trapped in excess solid neon and argon through metal atom reactions with boron trifluoride and identified by matrix isolation infrared spectroscopy and quantum chemical calculations. The FB≡MF2molecule features very high 11B–F stretching frequencies at 1586.6 cm–1(Ir), 1526.6 cm–1(Os), 1505.5 cm–1(Re), and 1453.2 cm–1(W), respectively. The very high strength of B≡M bonds with triple-bonding character is confirmed by EDA-NOCV calculations and the active molecular orbital and NBO analysis. The experimental observation of FB stabilization by heavy transition-metal atoms with triple bonds opens the door to design new boron–transition-metal complexes.

Echinococcus granulosus sensu stricto (s.s.), Echinococcus multilocularis and Echinococcus canadensis are the common causes of human echinococcosis in China. An accurate species identification tool for human echinococcosis is needed as the treatments and prognosis are different among species. The present work demonstrates a method for the simultaneous detection of these three Echinococcus species based on multiplex polymerase chain reaction (mPCR). Specific primers of this mPCR were designed based on the mitochondrial genes and determined by extensive tests. The method can successfully detect either separated or mixed target species, and generate expected amplicons of distinct size for each species. Sensitivity of the method was tested by serially diluted DNA, showing a detection threshold as less as 0.32 pg for both E. granulosus s.s. and E. canadensis , and 1.6 pg for E. multilocularis. Specificity assessed against 18 other parasites was found to be 100% except weakly cross-react with E. shiquicus. The assay was additionally applied to 69 echinococcosis patients and 38 healthy persons, confirming the high reliability of the method. Thus, the mPCR described here has high application potential for clinical identification purposes, and can further provide a useful tool for evaluation of serology and imaging method. [ABSTRACT FROM AUTHOR]

Laser-ablated group 2 metal atoms exhibit different reactivities with (CN)2in excess argon and neon during condensation at 4 K. UV irradiation (220–290 nm) is required to activate Be to produce the linear CNBeNC di-isocyanide molecule with a strong antisymmetric C–N stretching band at 2104.3 cm–1and a C-N-Be-N-C stretching mode at 1265.7 cm–1. The di-isocyanide appears at lower frequency and exhibits more nitrogen and less carbon isotopic shift than the cyanide counterpart, which is confirmed by B3LYP isotopic frequency calculations. Two weak bands were observed for the cyanide NCBeCN, and three absorptions were found for the mixed ligand CNBeCN molecule, which would be difficult to synthesize and put into a bottle. Mg reacts with (CN)2to form the CNMgNC counterpart at 2085.8 cm–1on annealing to 25 K. Absorptions for the Ca(NC)2, Sr(NC)2, and Ba(NC)2molecules at 2060.8, 2048.1, and 2045.9 cm–1increase on sample annealing with these more reactive heavier alkaline earth metal atoms, which have calculated twisted bowtie side-bound (CN) structures of C2symmetry with shorter computed M–N than M–C distances. NBO calculations for the latter molecules reveal natural charges of +1.54, 1.64, 1.71 e on the metal centers and – 0.77, 0.82, and 0.855 e on the corresponding CN subunits, with a doubly occupied sp–sp σ and two p–p π bonds on each (CN), which supports an ionic model for bonding in these molecules. A weaker band at 2056.6 cm–1behaves nearly the same as the Ca bowtie band in the spectrum on 25 K annealing and photolysis, and it is assigned to the 6 kJ/mol higher-energy linear CNCaNC isomer. Additional similar sharp absorptions for a new Ca, Sr, and Ba reaction product at 2036.3, 2040.6, and 2036.0 cm–1increase on annealing at the expense of adjacent broader bands: B3LYP and NBO calculations validate their assignment to ionic hexagonal C2h(MNC)2rings from the reaction of two M atoms with (CN)2.

Laser-ablated group 3 transition metal and cerium atom reactions with boron trifluoride were explored in excess solid neon at 4 K through matrix isolation infrared spectroscopy and quantum chemical calculations. The fluoroborylene complexes FBMF2(M = Sc, Y, La, Ce) were trapped in inert gas and identified by the isotopic substitutions. The observed frequencies of FBMF2were reproduced by DFT, NEVPT2, and CASSCF calculations. From Sc to La, the observed F–11B stretching mode has been observed at 1391.9 cm–1(Sc), 1370.8 cm–1(Y), and 1337.1 cm–1(La); however, for Ce this mode shifts up to 1340.8 cm–1, which is due to relativistic effects. The electron localization function (ELF) analysis and the theory of atoms in molecules (AIM) were applied to investigate the character of the B–M bond in FBMF2molecules, which favors bond order 1.5.

Reaction products of B, Al, and Ga atoms with H2S have been identified in solid argon using matrix isolation infrared absorption spectroscopy. The results show that the ground state B atom reaction with H2S gives the H2BS molecule while for the Al atom the HAlSH molecule forms first, which then further isomerizes to H2AlS upon >500 nm irradiation. The reaction of the Ga atom with H2S only takes place upon photolysis to produce HGaSH in the matrix. The assignments of the major modes for these products were confirmed by appropriate 10B, 11B, D2S, and H234S isotopic shifts and theoretical frequency calculations. Topological analysis of the electron density suggests that both HBSH and H2BS molecules possess covalent B–S bond with significant double bond character, while the M–S bond in the heavier group 13 homologues (Al, Ga) was characterized as a polar covalent strong interaction.

The reactions of laser-ablated C, Si, Ge, Sn, and Pb atoms with BF3have been studied using matrix isolation Fourier transform infrared (FTIR) spectroscopy and density functional theoretical (DFT) calculations. All atoms generate the inserted complex F2B–MF, which were trapped in inert gas and identified by the isotopic substitutions and DFT frequency calculations. DFT and CCSD(T) calculations show that triplet F2B–CF is the most stable isomer with two singly occupied molecular orbitals, while singlet F2B–MF (M= Si, Ge, Sn and Pb) molecules possess a near right angle B–M–F moiety with lone pair electrons on the M atom. The bonding difference between C and other group 14 atoms is mainly caused by relativistic effect, which is that, for heavier metal atom valences, s and p orbitals have a lower tendency to form hybrid orbitals.

Infrared absorptions of the matrix isolated OMS, OM(η2-SO), and OM(η2-SO)(η2-O2S) (M = Ce, Th) molecules were observed following reactions of laser-ablated Ce and Th metal atoms with SO2during condensation in excess argon and neon. Band assignments for the main vibrational modes were confirmed by appropriate 34SO2and S18O2isotopic shifts. B3LYP, BPW91 density functional, and CASSCF/CASPT2 calculations were performed to characterize these new reaction products and to explore the admixture of forbitals into the bonding giving stronger M≡O triple bonds. It is very interesting that both OM(η2-SO) and OM(η2-SO)(η2-O2S) molecules show chiral structure.

In this work, we propose a design of a double-scatterer structure to achieve complete conversion for elastic bulk waves. Every unit of the elastic metamaterial slab contains a pair of scatterers with a relatively oblique direction. When the slab attaches on a semi-infinite solid background, it can completely convert the normal incident longitudinal wave into the reflected shear wave, or vice versa. The conversion can be attributed to the in-phase coupling of the double scatterers’ quadrupolar resonances. The coupled two quadrupoles could interact with the background and bring oblique displacements. Consequently, the oblique displacements generate horizontal displacements for reflected waves.

This paper aims to reveal the depth distribution law of non-limit passive soil pressure on rigid retaining wall that rotates about the top of the wall (rotation around the top (RT) model). Based on Coulomb theory, the disturbance degree theory, as well as the spring-element model, by setting the rotation angle of the wall as the disturbance parameter, we establish both a depth distribution function for sand and a nonlinear depth distribution calculation method for the non-limit passive soil pressure on a rigid retaining wall under the RT model, which is then compared with experiment. The results suggest that under the RT model: the non-limit soil pressure has a nonlinear distribution; the backfill disturbance degree and the lateral soil pressure increase with an increase in the wall rotation angle; and, the points where the resultant lateral soil pressure acts on the retaining wall are less than 2/3 of the height of the wall. The soil pressure predicted by the theoretical calculation put forward in this paper are quite similar to those obtained by the model experiment, which verifies the theoretical value, and the engineering guidance provided by the calculations are of significance.

In this work, we study the conversions between longitudinal and transverse modes by one layer of oblique anisotropic dipolar resonators, whose size can be orders smaller than the wavelength. Mode conversions are found for both transmitted and reflected waves by such small resonators with a normal incidence. A mass-spring model is proposed to depict analytically the mode conversion, giving simplified analytical expressions for the conversion rates. The reflected conversion will gradually increase to the maximum while the solid material behind the resonators becomes soft, or vice versa. This work may provide theoretical guidance for practical applications.

In this work, total conversions between longitudinal and transverse modes are achieved within an elastic metamaterial plate with thickness of two orders smaller than the wavelength. The ultrathin metamaterial plate consists of an array of anisotropic dipolar resonators obliquely-oriented, which can transfer the longitudinal movement into the transverse one, or vice versa, accounting for this effect. A mass–spring model is developed to depict analytically the mode conversion with a quantitative agreement with the simulation. The conversion rate of the metamaterial plate remains above 95% in varying solids, showing good adaptability in practical applications.

The phase equilibria of the Co–Ni–Zr ternary system at 1 000 °C, 1 100 °C and 1 200 °C were experimentally investigated by means of back-scattered electron imaging, electron probe microanalysis and X-ray diffraction on the equilibrated ternary alloys. In this study, no ternary compound is found. The (aCo, Ni) phase region extends from the Ni-rich corner to the Co-rich corner with small solubility of Zr at three sections. At 1 000 °C and 1 100 °C, Ni5Zr, Co2Zr and Ni10Zr7phases have large solid solution ranges, but Ni10Zr7phase disappears at 1 200 °C. The Ni7Zr2, NiZr, Co11Zr2, Co23Zr6and CoZr phases exhibit nearly linear compounds in the studied sections, and have large composition ranges. Additionally, some differences in phase relationship exist among the above three isothermal sections.

A novel sensor deployment method utilize Discrete wavelet transform (DWT) is proposed, and the DWT is used to calculate the sub-band energy entropy to ascertain the coverage cavities in Wireless sensor networks (WSNs). We address the problem of deploying a limit number of sensors to optimize the coverage ratio in 3D surface, while it is a complex surface in space and sensors can be deployed only onto it. Another novel aspect of this paper is that the method followed utilizes an Artificial bee colony algorithm with dynamic search strategy (ABC-DSS), which mimics the behavior of bees, and the new modified ABC-DSS algorithm matches the sensor deployment problems on 3D surface well. The extensive simulations illustrate that comparing with the deployment method based on Particle swarm optimization (PSO) and ABC, the ABC-DSS which utilizes the wavelet sub-band energy entropy is functional and efficient on 3D surface deployment problems.

Patterned composites with custom-tailored properties are essential for efficient thermal management required by the increasing integration and complexity of devices. In this work, a facile approach for the fabrication of functional, robust, and patterned composites was demonstrated using a simple and scalable laser engraving technique. Graphene patterns were incorporated into composites by the single- or multiple-lasing on poly(Ph-ddm) substrate. The resultant composites exhibited a high thermal conductivity (8.2 W/(m·K)) that was equivalent to an enhancement of 45 times compared to pure matrix. This increase was attributed to the formed high-quality graphene porous architecture, which established an effective heat conduction channel. With the merit of computer-aided design of the laser trajectory, the processing method offers the freedom to tailor the heat transfer pathway in composites. Besides, the composites presented the favorable Joule heating performance in terms of fast and stable response with the heating efficiency up to 276 °C‧cm2/W. More interestingly, the heaters with designable thermal patterns were also allowed, in which the electrical property of each heating unit could be tailored by adjusting laser parameters. This provides a unique opportunity to simulate the real case of non-uniform heat sources in many electronic devices, which will facilitate the design and development of heating dissipation systems. The material/process developed promises a wide range of possibilities for the efficient thermal management applications.

Electrospinning is an effective way to prepare two-dimensional nanofiber membranes. However, it is difficult to increase the thickness of the film by simply increasing the spinning time, thus limiting the potential applications of electrospinning. In this paper, we present a simple and stable method for preparing three-dimensional “marshmallow-shape” fiber sponges. By adding urea to the polyacrylonitrile polymer spinning solution, the humidity response of the nanofibers in the electrospinning environmental field could be enhanced, speeding up the hardening process of the nanofibers and forming a three-dimensional structure. The resulting three-dimensional “marshmallow-shaped” fiber sponge has a low bulk density (0.9 mg/cm3), good compression recovery, and good hydrophobicity (WCA = 135.6°). Moreover, good compression recovery after carbonization could be achieved by maintaining its original thickness, as well as with a strong oil-based organic solvent adsorption capacity.

Most of the SARS‐CoV‐infected patients spontaneously recovered without clinical intervention while a small percentage succumbed to the disease. Here, we characterized temporal changes in N protein‐specific and S glycoprotein‐specific neutralizing antibody (Nab) responses in infected patients who have either recovered from or succumbed to SARS‐CoV infection. Recovered patients were found to have higher and sustainable levels of both N protein‐specific and S glycoprotein‐specific Nab responses, suggesting that antibody responses likely play an important role in determining the ultimate disease outcome of SARS‐CoV‐infected patients. J. Med. Virol. 78:1–8, 2006. © 2005 Wiley‐Liss, inc.

ABSTRACTHuman immunodeficiency virus type 1 is characterized by extensive genetic heterogeneity. Having previously demonstrated that, in the peripheral blood, the initial viral population is more homogeneous than at subsequent stages of infection, we have extended our studies to tissue samples, allowing comparisons between viral populations in peripheral blood and tissues during both the acute and chronic stages of infection. We found that homogeneity in gp120 sequences during the acute infection phase is not just restricted to the peripheral blood but also extends to other tissue compartments. However, in chronically infected individuals, heterogeneous and distinct viral populations were found in different compartments. We therefore conclude that the dominant and homogeneous viral population observed during the acute infection phase is likely to infiltrate lymphoid tissues and form the genetic bases for subsequent diversification. It is therefore likely that the compartmentalization of viral sequences observed in chronically infected patients reflects a gradual diversification of a common dominant viral variant rather than the preferential migration of distinct viral populations to different tissue compartments at the beginning of infection.

Reactions of MH2(M = Sr, Ba) with CO2were explored in pure parahydrogen at 3.5 K using matrix isolation infrared spectroscopy and quantum chemical calculations. The formate complex HM(η2-O2CH) and formic acid complex (MH2)(HCOOH) were trapped and identified by isotopic substitutions and density functional theory (DFT) frequency calculations. Natural population analysis and the CO2reduction mechanism demonstrate that hydride ion transfer from a metal hydride to a CO2moiety facilitates the stabilization of such complexes.

On reacting laser-ablated manganese or iron difluorides with O2or O3during codeposition in solid neon or argon, infrared absorptions of several new metal oxo-fluoride molecules, including OMF2, (η1-O2)MF2, (η2-O3)MF2, (η1-O2)2MF2(M = Mn and Fe), and O2MnF, have been observed. Quantum chemical density functional and multiconfiguration wavefunction calculations have been applied to characterize these new products by their geometric and electronic structures, vibrations, charges, and bonding. The assignment of the main vibrational absorptions as dominant symmetric or antisymmetric M–F or M–O stretching modes is confirmed by oxygen isotopic shifts and quantum chemical calculations of frequencies and thermal stabilities. The tendency of Fe to form polyoxygen complexes in lower oxidation states than the preceding element Mn is affirmed experimentally and supported theoretically. The M–F stretching frequencies of the isolated metal oxo-fluorides may provide a scale for the local charge on the MF2sites in active energy conversion systems. The study of these species provides insights for understanding the trend of oxidation state changes across the transition-metal series.

Matrix isolation infrared spectroscopy has been employed to study the reaction of laser-ablated boron atoms with hydrogen selenide in a 5 K solid argon matrix. On the basis of the isotopic shifts as well as the theoretical frequency calculations, triatomic molecule BSe2and its anion BSe2–were identified. Both BSe2and BSe2–were predicted to have D∞hsymmetric structures with nearly identical structure parameters and bond strengths by quantum chemical calculations. Whereas the observed antisymmetric B–Se stretching frequency of BSe2is much lower than that of BSe2–, the anomalously low antisymmetric B–Se stretching frequency of BSe2is attributed to a pseudo-Jahn–Teller effect due to the mixing of the X2Πgground state with the A2Πuexcited state. In addition, H2BSe, HBSe, and HSeBSe molecules were produced in the reaction.

Strain-adjusting the band gap of MoS2using patterned substrates to improve the photoelectric performance of MoS2has gradually become a research hotspot in recent years. However, there are still difficulties in obtaining high-quality two-dimensional materials and preparing photodetectors on patterned substrates. To overcome this, a continuous multilayer MoS2film was transferred to a patterned gallium nitride substrate (PGS) for the fabrication of photodetectors, and density functional theory calculations showed that the band gap of the MoS2film increased and that the electron effective mass decreased due to the introduction of PGS. In addition, finite difference time domain simulation showed that the electric field in the MoS2area on the PGS is enhanced compared with that on the flat gallium nitride substrate due to the enhanced light scattering effect of the PGS. The photoresponse of the MoS2/PGS photodetector at 460 nm was also enhanced, with Iphincreasing by 5 times, Rincreasing by 2 times, NEP decreasing to 3.88 × 10–13W/Hz1/2, and D*increasing to 5.6 × 108Jones. Our research has important guiding significance in adjusting the band gap of MoS2and enhancing the photoelectric performance of MoS2photodetectors.

Abstract: Adsorption is a promising technique for water treatment. Porous aromatic frameworks (PAFs) have been witnessed as advanced adsorbents for various applications and PAFs with task-specific functionality and porosity are desirable adsorbents. Herein, a charged PAF, PAF-CH2N(CH3)3I, was prepared through precursor-designed method. The charged PAF is densely and homogeneously functionalized with cationic groups and featured with hierarchical pore structure. The content of the charged groups in the framework reaches up to 52.27 wt% and the hierarchical structure facilitates fast adsorption/desorption of dye molecular. It demonstrates strong affinity, fast adsorption rate, high adsorption efficiency and high adsorption capacity towards not only small model anionic dye but also large-sized one, which can not be adsorbed efficiently by other microporous adsorbents. In addition, benefiting from the hierarchical structure, the charged PAF can be easily regenerated and reused with almost no loss of its efficiency even after 10 adsorption–desorption cycles. These excellent features demonstrate that the charged PAF is a promising adsorbent for wastewater treatment and this study provides a new perspective to explore functionalized PAFs as a versatile type of advanced adsorbents. Graphic abstract:

Ternary NiSi2?xAlxlayer with uniform and smooth NiSi2?xAlx/Si interface has been achieved by Al interlayer mediated epitaxy. A 3 nm Al interlayer is introduced to the Nickel silicidation on Si(001) substrate. The morphology, composition, and micro-structure of the Ni silicide layers are analyzed for different annealing temperatures. It is found that under the assistance of Al atoms, the best quality Ni silicide layer is achieved by annealing at 700 °C. The reduced Ni diffusion and the modified energetics are conducive for the uniform reaction between Ni and Si, resulting in epitaxial ternary NiSi2?xAlxlayer on Si(001) substrate.

In this paper, we report the formation of vertical GaN Schottky barrier diodes (SBDs) on a 2-in. free-standing (FS) GaN wafer, using CMOS-compatible contact material. By realizing an off-state breakdown voltage V BR of 1200 V and an on-state resistance R on of 7 mO*cm2, the FS-GaN SBDs fabricated in this work achieve a power device figure-of-merit $V_{\text{BR}}^{2}/R_{\text{on}}$ of 2.1 x 108 V2*O[?]1*cm[?]2 on a high quality GaN wafer. In addition, the fabricated FS-GaN SBDs show the highest I on/I off current ratio of [?]2.3 x 1010 among the GaN SBDs reported in the literature.

We report the fabrication and characterization of high voltage AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors (MOSHEMTs) with selectively regrown In0.14Ga0.86N contact using a CMOS compatible gold-free process. Device with the regrown InGaN contact with a gate-to-drain spacing LGDof 5 µm achieves an off-state breakdown voltage VBRof 800 V and on-state resistance Ronof 2 m?·cm2. The VBRachieved in this work is higher than those of gold-free GaN MOSHEMTs with gate-to-drain spacing LGDbelow 10 µm.

The continuous downscaling in metal-oxide-semiconductor field effect transistors is approaching fundamental limits. Allied to new device architectures, novel materials are needed in order to continue the evolution of complementary metal-oxide-semiconductor technologies. The combination of high dielectric constant (k) oxides with silicon and other semiconductors having a higher charge carrier mobility (ex.: germanium) is currently a fundamental technologic issue that requires extensive investigation on materials science. The search for high-k oxides (with k > 20) that can offer stable interfaces combined with a low density of electrically active defects is a topic of major interest. In this contribution, we will review some of our results on the structural and electrical properties of REScO3 (RE = La, Gd, Tb, Sm) and LaLuO3 amorphous films on Si as well as on high mobility substrates, showing their potential as high-k dielectrics for future CMOS applications.