Search

Background: For the spinal internal fixation procedures, connecting rods to the pedicle screws are commonly used in all spinal segments from the cervical to sacral spine. So far, we have only seen single vertebral screw trajectory planning methods in literatures. Joint screw placements in multi‐level vertebrae with the constraint of an ipsilateral connecting rod are not considered. Purpose: In this paper, a screw trajectory planning method that considers screw‐rod joint system with both multi‐level vertebral constraints and individual vertebral safety tolerance are proposed. Methods: The proposed method addresses three challenging constraints jointly for multi‐level vertebral fixation with pedicle screws. First, a cylindrical screw safe passage model is suggested instead of a unique mathematical optimal trajectory for a single pedicle. Second, the flexible screw cap accessibility model is also included. Third, the connecting rod is modeled to accommodate the spine contour and support the needed gripping capacity. The retrospective clinical data of relative normal shape spines from Beijing Jishuitan hospital were used in the testing. The screw trajectories from the existing methods based on single vertebra and the proposed method based on multi‐level vertebrae optimization are calculated and compared. Results: The results showed that the calculated screw placements by the proposed method can achieve 88% success rate without breaking the pedicle cortex and 100% in clinical class A quality (allow less than 2 mm out of the pedicle cortex) compared to 86.1% and 99.1%, respectively, with the existing methods. Expert evaluation showed that the screw path trajectories and the connecting rod calculated by the new method satisfied the clinical implantation requirements. Conclusions: The new screw planning approach that seeks an overall optimization for multi‐level vertebral fixation is feasible and more advantageous for clinical use than the single vertebral approaches. [ABSTRACT FROM AUTHOR]

As the pursuit of greater energy density for the portable battery has stimulated exhaustive research in high‐voltage lithium‐ion batteries (LIBs), developing electrolyte additives is considered a cost‐efficient way to improve the performance of the battery. Here, the three interactional issues of LiCoO2 (LCO) batteries in commercial electrolytes at high voltage are summarized, this review first identifies an unavoidable vicious cycle of the commercial electrolyte at high voltage. LCO/electrolyte interphase break, dissolution of transition metal (TM) ions, and formation of harmful HF accelerate the failing progress of the commercial electrolyte at high voltage, besides the malfunction of anode happens at the same time because of electrode crosstalk. Then, the modification of the commercial electrolyte is summarized according to the solutions of this vicious cycle. Last, a framework for future research on high‐voltage LCO batteries is outlined. [ABSTRACT FROM AUTHOR]

We present the development of a simple, handheld cross‐polarised microscope (CPM) and demonstration of imaging individual pigmented cells in human skin in vivo. In the CPM device, the cross‐polarised detection approach is used to reduce the specular reflection from the skin surface and preferentially detect multiply‐scattered light. The multiply‐scattered light works as back illumination from within the tissue towards the skin surface, and superficial pigment such as intraepidermal melanin absorbs some spectral bands of the multiply‐scattered light and cast coloured shadows. Since the light that interacted with the superficial pigment only needs to travel a short distance before it exits the skin surface, microscopic details of the pigment can be preserved. The CPM device uses a water‐immersion objective lens with a high numerical aperture to image the microscopic details with minimal spherical aberrations and a small depth of focus. Preliminary results from a pilot study of imaging skin lesions in vivo showed that the CPM device could reveal three‐dimensional distribution of pigmented cells and intracellular distribution of pigment. Co‐registered CPM and reflectance confocal microscopy images showed good correspondence between dark, brown cells in CPM images and bright, melanin‐containing cells in reflectance confocal microscopy images. LAY DESCRIPTION: We present the development of a simple, handheld cross‐polarised microscope (CPM) and demonstration of imaging individual pigmented cells in human skin in vivo. In the CPM device, the cross‐polarised detection approach is used to reduce the specular reflection from the skin surface and preferentially detect multiply‐scattered light. The multiply‐scattered light works as back illumination from within the tissue towards the skin surface, and superficial pigment such as intraepidermal melanin absorbs some spectral bands of the multiply‐scattered light and cast coloured shadows. Since the light that interacted with the superficial pigment only needs to travel a short distance before it exits the skin surface, microscopic details of the pigment can be preserved. Preliminary results from a pilot study of imaging skin lesions in vivo showed that the CPM device could reveal three‐dimensional distribution of pigmented cells and intracellular distribution of pigment. Co‐registered CPM and reflectance confocal microscopy images showed good correspondence between dark, brown cells in CPM images and bright, melanin‐containing cells in reflectance confocal microscopy images. [ABSTRACT FROM AUTHOR]

A new method for the formation of 1,1-difluoroethyl copper species ('CuCF2CH3') with 1,1-difluoroethylsilane (TMSCF2CH3) has been developed. The 'CuCF2CH3' species can be applied to the efficient 1,1-difluoroethylation of diaryliodonium salts under mild conditions, affording (1,1-difluoroethyl)arenes in good to excellent yields. This convenient procedure tolerates a wide range of functional groups and thus serves as a practical synthetic tool for the introduction of CF2CH3 group(s) into complex molecules. [ABSTRACT FROM AUTHOR]

Investigating fatigue crack growth behavior of materials is crucial to the life design and safety evaluation of engineering structures. During the practical service condition, the temperature keeps changing, which cannot be studied by the traditional fatigue crack growth test method at constant temperature. In this study, we focus on constructing a new thermomechanical fatigue (TMF) crack propagation testing method, developing a thermal deformation compensation method, and proposing an equivalent compliance method suitable for variable temperature conditions based on ASTM E647 standard to measure the crack length. Furthermore, the load‐ and strain‐controlled TMF tests under different phase angles are carried out to prove the validity of the new method. Highlights: A temperature compensation method for the variable temperature test is proposed.A modified compliance method for crack length measurement is developed.The thermomechanical fatigue (TMF) crack propagation testing method was standardized.Only the stress intensity factor range ΔK cannot be used to characterize the fatigue crack growth rate. [ABSTRACT FROM AUTHOR]

A sodium bis(fluorosulfonyl)imide (NaFSI)‐based multifunctional electrolyte is developed by partially replacing NaPF6 salt in the electrolyte to improve the wide temperature range working capability of NaNi1/3Fe1/3Mn1/3O2/hard carbon (NNFM111/HC) sodium‐ion batteries (SIBs). The capacity retention of the SIBs with NaFSI‐NaPF6 dual salt electrolyte increases from 47.2 % to 75.5 % after 250 cycles at 25 °C, and from 51.0 % to 82.3 % after 80 cycles at 45 °C, and the 1 C discharge capacity retention at the low temperature of −20 °C also increases 26.8 %. In the single salt system, NaPF6 effectively passivate the aluminum foil and NaFSI passivate the electrode/electrolyte interface. The synergistic effect of NaPF6 and NaFSI greatly improves the battery performance in a wide temperature range. This NaFSI‐based dual salt electrolyte also effectively overcomes the flaws when the SIBs using NaFSI or NaPF6 independently, and makes it more suitable for SIBs, indicating promising prospects in the commercial application of NNFM111/HC SIBs. [ABSTRACT FROM AUTHOR]

Bismuth (Bi) possesses an ultrahigh theoretical volume capacity (3800 mAh cm−3) and low embedding potential stimulated considerable attention as anodes for sodium‐ion batteries (SIBs). However, its practical application is still hampered by the huge volume variation during the charge/discharge process. To settle this issue, Bi@C nanosheet arrays (Bi@C‐NSA) are fabricated on copper foam via a facile galvanic replacement followed by in situ polymerization of dopamine and an annealing procedure. The carbon‐coated nanosheet array structure not only accommodates the volume expansion during cycling and maintains electrode stability, but also facilitates rapid electron/ion transport. Due to the unique structural design, this Bi@C‐NSA exhibits an impressive capacity of 315.72 mAh g−1 after 1500 cycles under 1 A g−1. Furthermore, a series of in situ/ex situ techniques reveal that this Bi@C‐NSA possesses superior reaction kinetics and undergoes a typical alloying/dealloying storage mechanism. Furthermore, Bi@C‐NSA also achieves commendable reversible capacity and cycling stability in a wide temperature range (0 °C–60 °C). Notably, the assembled Na3V2(PO4)3//Bi@C‐NSA full cell demonstrates a capacity of 325 mAh g−1 after 50 cycles at 0.05 A g−1, which promises for practical applications. This galvanic replacement strategy spearheads a way to prepare nanoarray electrodes and will accelerate the development of sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

TiSiCN composite coatings with different C contents were prepared on Cr buffer layer by plasma‐enhanced magnetron sputtering. The structure, composition, surface, and cross‐sectional morphology of the coatings were characterized by X‐ray photoelectron spectroscopy, X‐ray diffraction, Raman spectroscopy, scanning electron microscope, and atomic force microscope. The hardness, elastic modulus, and tribological performance of the coatings were evaluated by nanoindentation and reciprocating friction tests. The results showed that the TiSiCN composite coatings are amorphous structure composed of TiCN compound and microcrystalline graphite, and amorphous phases. The increase of C content changed the content and distribution of TiCN ceramics nanocrystal, amorphous Si3N4 and amorphous carbon (sp3‐ and sp2‐hybridized C), thus affecting the hardness and friction behavior of the coatings. The hardness of the composite coatings was related to the content of TiCN phase and sp3‐C in the coatings. The TiSiCN composite coating with C content of 68.2% had lower coefficient of friction and the lowest wear rate. [ABSTRACT FROM AUTHOR]

Lithium‐ion batteries (LIBs) have dominated the secondary batteries market in the past few decades. However, their widespread application is seriously hampered by the limited lithium resource and high cost. Recently, sodium‐ion batteries (SIBs) have generated significant attention because of their characteristics of abundant raw sources, low cost, and similar "rocking chair" mechanism with LIBs, which hold great application potential in large‐scale energy storage. Cathode materials with excellent electrochemical performance are in urgent demand for next‐generation SIBs. Herein, this review provides a comprehensive overview of the recent advances of the most promising SIBs cathode candidates, including layered oxides, polyanionic materials, and Prussian blue analogues. The currently existing issues that need to be addressed for these cathodes are pointed out, such as insufficient energy density, low electron conductivity, air sensitivity, and so on. This review also details the structural characteristics of these three cathode candidates. Moreover, the recent optimization strategies for improving the electrochemical performance are summarized, including element doping, morphology modification, structure architecture, and so on. Finally, the current research status and proposed future developmental directions of these three cathode materials are concluded. This review aims to provide practical guidance for the development of cathode materials for next‐generation SIBs. [ABSTRACT FROM AUTHOR]

The practical title reaction tolerates various functional groups, including complex steroids. [ABSTRACT FROM AUTHOR]

The ceramics with the formula of Sr1−xSm2x/3TiO3 (x = 0‐0.5) were prepared by conventional ceramic process. A single phase of SrTiO3‐type with cubic perovskite structure was found companied with a decrease in crystal volume when x < 0.5, which was confirmed by X‐ray diffraction results and Rietveld refine. At the level of x = 0.5, the sample consisted of two phases of SrTiO3‐type and Sm2Ti2O7. Raman spectra were used to confirm the change of vibration to explain the variation in microwave dielectric properties. The dielectric constant decreased, the quality factor increased, and the temperature coefficient shifted negatively, when the x value increased from 0 to 0.4. When the x value located between 0.3 and 0.4, the ceramics exhibited high dielectric constant of 140‐152, high quality factor (>6000). [ABSTRACT FROM AUTHOR]

The reagent 'PhSO2CF2Cu' is generated in the reaction from sulfone (I) and it further reacts with aryl- and heteroarylboronic acids to afford the desired products. [ABSTRACT FROM AUTHOR]

In the present work, a comparison between traditional oil‐in‐water (O/W) based lubricant and nano‐TiO2 additive water‐based lubricants was made to explore the lubrication effects during rolling of ferritic stainless steel (FSS) strips. The results show that marked reduction in rolling force and improvement in the surface quality can be achieved by utilisation of water‐based nanolubricant, which can be attributed to the synergism of rolling effect, mending effect, polishing effect and protection film. An optimal concentration of 3.0 wt% TiO2 nanoparticles is found to exhibit excellent lubrication effects with sufficient nanoparticles at real contact regions without aggregation, leading to 10% reduction in the surface roughness during rolling of FSS strips. [ABSTRACT FROM AUTHOR]

The preparation of a 'CuCF3' species and its application in the trifluoromethylation of aryl iodides and activated aryl bromides as well as its cross-coupling with terminal alkynes and aryl boronic acids are described. [ABSTRACT FROM AUTHOR]

Polyethylene oxide (PEO)‐based polymer electrolytes with good flexibility and viscoelasticity, low interfacial resistance, and fabricating cost have caught worldwide attention, but their practical application is still hampered by the instability at high voltages and the low ionic conductivity (10−8 to 10−6 S cm−1). Herein, we rationally designed defects‐abundant Ga2O3 nanobricks as multifunctional fillers and constructed a PEO‐based organic‐inorganic electrolyte for lithium metal batteries. Due to the abundant O‐defects feature of Ga2O3 filler, this PEO‐based composite electrolyte not only broadens electrochemical stability window (over 5.3 V versus Li/Li+) but also in situ forms a Li–Ga alloy and solid electrolyte interphase (SEI) film during the cycling process causing a rapid diffusion of Li+ ions. The as‐prepared electrolyte has good interface compatibility with Li metal (without short‐circuiting over 500 h at 0.2 mA cm−2) and possesses superior high ionic conductivity. The assembled all‐solid‐state LiFePO4//Li cells attained an excellent cycling performance of 146 mAh g−1 over 100 cycles at 0.5 C. The XPS analysis reveals that Ga2O3 nanobricks can form in situ a Li−Ga alloy layer at the polymer/anode interface. This work shed a light on designing high ionic conductivity lithium alloys in the composite electrolyte, which can improve the electrochemical properties of PEO‐based polymer electrolytes. [ABSTRACT FROM AUTHOR]

Herein, an efficient and regioselective Rh(III)‐catalyzed [4+2] annulation/lactonization cascade of indoles with 4‐hydroxy‐2‐alkynoates at room temperature to access the furo[3′,4′:4,5]pyrimido[1,6‐a]indole‐1,5(3H,4H)‐diones is described. This method features mild reaction conditions, operational simplicity, excellent regioselectivity, broad substrate scope with good functional group tolerance, and good to excellent yields. [ABSTRACT FROM AUTHOR]

Bamboo is one of the fastest growing plants in the world, but their shoot buds develop very slowly. Information about the sugar storage and metabolism during the shoot growth is lacking. In the present study, we determined the activity of sucrose and starch metabolizing enzymes during the developmental period of Fargesia yunnanensis from shoot buds to the young culms that have achieved their full height. The soluble sugars and starch contents were also determined and analyzed in shoot buds and shoots at different developmental stages. The results showed that there were higher sucrose contents in shoot buds than shoots, which coincides with the sweeter taste of shoot buds. As the shoot buds sprouted out of the ground, the starch and sucrose were depleted sharply. Coupled with this, the activity of soluble acid invertase (SAI), cell wall‐bound invertase (CWI), sucrose synthase at cleavage direction (SUSYC) and starch phosphorylase (STP) increased significantly in the rapidly elongating internodes. These enzymes dominated the rapid elongation of internodes. The activities of SAI, CWI, SUSYC and STP and adenosine diphosphate‐glucose pyrophosphorylase were higher as compared to other enzymes in the shoot buds, but were far lower than those in the developing shoots. The slow growth of shoot buds was correlated with the low activity of these enzymes. These results complement our understanding of the physiological differences between shoot buds and elongating shoots and ascertain the physiological mechanism for the rapid growth of bamboo shoots. [ABSTRACT FROM AUTHOR]

1,3‐unsubstituted 2‐(1H‐indol‐2‐yl)ethanamines were employed for the first time to react with alkynoic acids (AAs) to achieve gold‐catalyzed highly selective cascade reactions to furnish novel indole‐fused skeletons. Furthermore, with this powerful gold catalytic system, a library of indole/pyrrole/thiophene/benzene/naphthalene/pyridine‐based nitrogen‐containing heterocyclic compounds (NCHCs) with scaffold diversity and molecular complexity was constructed rapidly using various amine nucleophiles (ANs) and diverse AAs as the building blocks. This general protocol features excellent selectivity, extraordinarily broad substrate scope, readily available inputs, good to high yields, high bond‐forming efficiency, and step economy, thus providing a facile and efficient access to a variety of valuable nitrogen‐containing heterocycles. [ABSTRACT FROM AUTHOR]

In this paper, the effect of transverse thickness difference and width-to-thickness ratio on the critical unstable shape of cold-rolled strip is studied computationally and experimentally. Firstly, the influence model under actual working conditions is developed by referring to the basic relationship between transverse thickness difference and shape under ideal conditions. After that, the combined influence of transverse thickness difference and width-to-thickness ratio on the critical unstable shape is analyzed based on the elastic sheet stability model. Experimental validations demonstrate that during the production of ultrathin strip steel with different width-to-thickness ratios, the loading roller shapes should be fine adjusted according to the transverse thickness difference of input strips. Therefore, the variation of transverse thickness difference of output strips can meet the requirement of shape stability, so as to obtain fine shape. [ABSTRACT FROM AUTHOR]

In this paper, the isothermal oxidation of the indefinite chill (IC) roll is investigated by using a thermogravimetric analyzer (TGA) from 550 to 700 °C under dry and humid atmospheres. It is found that the oxidation kinetics follow a linear trend and the oxide scale consists of two layers after the oxidation in dry air but three layers in humid air above 600 °C. In dry air, the graphite is covered by the oxide scale above 650 °C. The water vapor accelerates the oxidation of the matrix and the graphite. The graphite is covered by the extension of the oxide scale above 600 °C in humid air. The as-treated samples are examined with SEM and XRD, while the kinetics is based on TGA results. [ABSTRACT FROM AUTHOR]