The martensite multi-level microstructures of 20CrNi2Mo steel, which were quenched at the different temperatures of 900–1200°C and tempered at 200°C, were investigated by optical microscope (OM), ...scanning electron microscopy (SEM), electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM), and the relationship between the microstructures and properties of strength and toughness was discussed by the classic formula of Hall–Petch. The results show that the size of prior austenite grain (dr), martensite packet (dp) and block (db) increase with increasing of the quenching temperature, while the martensite lath (dl) size is opposite. On another hand, the confusion degree of the martensite packets changes from disorder to order. The boundaries of prior austenite grain, packet, block and the martensite lath are high angle boundaries (HBs) and low angle boundaries (LBs), respectively, and the ratio of the low angle boundaries increase with the quenching temperature by calculating to the multi-level microstructure size with the mathematical model established by myself. In addition, the relationship between the packet/block and strength follows the classical formula of Hall–Petch, and the size of db is far lower than the size of dp, db is the effective control unit of the strength. Meanwhile, dl is the effective control unit of toughness because it strongly impacts the crack initiation and propagation and follows also the Hall-Petch with toughness in 20CrNi2Mo steel.
Partial least squares (PLS) have gained wide applications especially in chemometrics, metabolomics/metabonomics as well as bioinformatics. Here, we present libPLS, a library that integrates not only ...basic PLS modeling algorithms but also advanced and/or recently developed methods on model assessment, outlier detection, and variable selection. This package is featured in a set of Model Population Analysis (MPA)-type approaches that have not been integrated into a single package yet and thus functionally complement existing toolboxes. libPLS provides an integrated platform for developing PLS regression and/or linear discriminant analysis (PLS-LDA) models. It is written in MATLAB and freely available at www.libpls.net.
•Provide an integrated library for partial least squares regression and discriminant analysis.•Featured in model population analysis approaches.•Contain a series of versatile variable selection methods.
Environmentally friendly composites made of poly(vinyl alcohol) and carboxymethyl cellulose (PVA/CMC) hydrogels were proposed. The PVA/CMC hydrogels were prepared by freeze–thaw processes and ...applied to adsorb heavy metal ions including Ag+, Ni2+, Cu2+, and Zn2+. The phase separation of polymer solutions during freezing stages led to the formation of crystallites and resulted in insoluble hydrogels. The PVA/CMC hydrogels were effectively acquired, confirmed by at least 71% of insoluble gels found in the gel fraction. In addition, the gel fraction, physical properties, and swelling ratios were clearly modulated by the compositions of PVA and CMC among the samples of pure PVA, P2C1 (containing two-thirds of PVA and one-third of CMC), P1C1, and P1C2 hydrogels. For pure PVA hydrogels, the swelling ratio was 416%, while the P1C2 hydrogels exhibited a much higher swelling ratio (1437%). For the metal adsorption, the experimental results indicated that the P2C1 hydrogels presented not only the highest adsorption capacity toward Ag+ (8.4 mg per gram of hydrogel) but also the highest selectivity toward Ag+ in the mixed solutions. Interestingly, the experimental results revealed clearly that the adsorbed metal ions were further reduced on the P2C1 hydrogels. In summary, an insoluble hydrogel composed of PVA/CMC with excellent capacity of adsorbing metal ions was prepared in an economic and energy-saving manner. The prepared hydrogels showed potential applications for removal of heavy metal ions and wastewater treatment.
When the bond lengths of 11 molecules containing van der Waals bonds are optimized by 572 methods and 20 basis sets, it is found that the best mean absolute deviations (MADs) of density-functional ...theory (DFT) methods are 0.005 Å (shown by APFD/6-311++G**), 0.007 Å (B2PLYPD3(Full)/aug-cc-pVQZ), and 0.010 Å (revDSDPBEP86/aug-cc-pVQZ), while the best MADs of ab initio methods are 0.008 Å (BD(T)/aug-cc-pVTZ) and 0.016 Å (MP4/aug-cc-pVQZ). Moreover, the best MADs calculated by 54 selected methods in combination with 60 other basis sets (such as 6-311++G, 6-31++G(3d'f,3p'd), and UGBS1V++) are not better. Therefore, these bond lengths can be calculated with extremely high accuracy by some special methods and basis sets, and CCSD(T) is also not as good as expected because its best MAD is only 0.023 Å (CCSD(T)/aug-cc-pVQZ).
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•Cu/Cu2O/CuO ternary composite was prepared in a furnace aerosol reactor.•Cu/Cu2O/CuO composite was demonstrated for electrochemical detection of glucose.•Cu/Cu2O/CuO composite showed ...high sensitivity and selectivity in detecting glucose.•Compared to Cu/Cu2O and CuO, the Cu/Cu2O/CuO showed greatly enhanced sensitivity.•The sensitivity of Cu/Cu2O/CuO for glucose detection was 8726 μA cm−2 mM−1.
A novel ternary composite, Cu/Cu2O/CuO hollow spheres (HSs), synthesized using an aerosol furnace reactor (FuAR) was investigated for the first time as a non-enzymatic electrochemical biosensor for glucose detection. The composite HSs were synthesized by aerosolizing a mixture of copper nitrate, citric acid, and ammonia through a FuAR. Interestingly, the addition of ammonia played a crucial role in the in-situ formation of hollow Cu/Cu2O/CuO ternary composites. The HSs modified electrode was employed for non-enzymatic glucose detection where it exhibited a detection limit of 0.39 μM and an outstanding sensitivity of 8726 μA cm−2 mM−1 which is superior to existing Cu/Cu2O HSs and CuO HSs modified electrodes. The high sensitivity was attributed to the synergy arising from the ternary composition’s interfacing with multiple Cu redox couples and high surface area. The Cu/Cu2O/CuO HSs modified electrode also showed excellent selectivity in detecting glucose in the presence of interfering species, including chloride salts of Na+, K+, Ca2+, and anions of ascorbic acid (AA), dopamine (DA), and uric acid (UA). This simple and scalable FuAR technique will attract interest and enable in designing other high-performance metal/metal oxide composites for commercial glucose sensing applications.
Analysis of short tandem repeats (STRs) is a global standard method for human identification. Insertion/Deletion polymorphisms (DIPs) can be used for biogeographical ancestry inference. Current DNA ...typing involves a trained forensic worker operating several specialized instruments in a controlled laboratory environment, which takes 6–8 h. We developed the Quick TargSeq 1.0 integrated system (hereinafter abbreviated to Quick TargSeq) for automated generation of STR and DIP profiles from buccal swab samples and blood stains. The system fully integrates the processes of DNA extraction, polymerase chain reaction (PCR) amplification, and electrophoresis separation using microfluidic biochip technology. Internal validation studies were performed using RTyper 21 or DIP 38 chip cartridges with single‐source reference samples according to the Scientific Working Group for DNA Analysis Methods guidelines. These results indicated that the Quick TargSeq system can process reference samples and generate STR or DIP profiles in approximately 2 h, and the profiles were concordant with those determined using traditional STR or DIP analysis methods. Thus, reproducible and concordant DNA profiles were obtained from reference samples. Throughout the study, no lane‐to‐lane or run‐to‐run contamination was observed. The Quick TargSeq system produced full profiles from buccal swabs with at least eight swipes, dried blood spot cards with two 2‐mm disks, or 10 ng of purified DNA. Potential PCR inhibitors (i.e., coffee, smoking tobacco, and chewing tobacco) did not appear to affect the amplification reactions of the instrument. The overall success rate and concordance rate of 153 samples were 94.12% and 93.44%, respectively, which is comparable to other commercially available rapid DNA instruments. A blind test initiated by a DNA expert group showed that the system can correctly produce DNA profiles with 97.29% genotype concordance with standard bench‐processing methods, and the profiles can be uploaded into the national DNA database. These results demonstrated that the Quick TargSeq system can rapidly generate reliable DNA profiles in an automated manner and has the potential for use in the field and forensic laboratories.
Sequence-derived structural and physiochemical features have been frequently used for analysing and predicting structural, functional, expression and interaction profiles of proteins and peptides. To ...facilitate extensive studies of proteins and peptides, we developed a freely available, open source python package called protein in python (propy) for calculating the widely used structural and physicochemical features of proteins and peptides from amino acid sequence. It computes five feature groups composed of 13 features, including amino acid composition, dipeptide composition, tripeptide composition, normalized Moreau-Broto autocorrelation, Moran autocorrelation, Geary autocorrelation, sequence-order-coupling number, quasi-sequence-order descriptors, composition, transition and distribution of various structural and physicochemical properties and two types of pseudo amino acid composition (PseAAC) descriptors. These features could be generally regarded as different Chou's PseAAC modes. In addition, it can also easily compute the previous descriptors based on user-defined properties, which are automatically available from the AAindex database.
The python package, propy, is freely available via http://code.google.com/p/protpy/downloads/list, and it runs on Linux and MS-Windows.
Supplementary data are available at Bioinformatics online.
Oxygen isotope records from Chinese caves characterize changes in both the Asian monsoon and global climate. Here, using our new speleothem data, we extend the Chinese record to cover the full ...uranium/thorium dating range, that is, the past 640,000 years. The record's length and temporal precision allow us to test the idea that insolation changes caused by the Earth's precession drove the terminations of each of the last seven ice ages as well as the millennia-long intervals of reduced monsoon rainfall associated with each of the terminations. On the basis of our record's timing, the terminations are separated by four or five precession cycles, supporting the idea that the '100,000-year' ice age cycle is an average of discrete numbers of precession cycles. Furthermore, the suborbital component of monsoon rainfall variability exhibits power in both the precession and obliquity bands, and is nearly in anti-phase with summer boreal insolation. These observations indicate that insolation, in part, sets the pace of the occurrence of millennial-scale events, including those associated with terminations and 'unfinished terminations'.
Dry sliding wear tests of steel disks of various compositions were performed with consideration of the effects of microstructure, shear strain and shear strain rate using a ball-on-disk tester with a ...tungsten carbide ball under ambient atmosphere and room temperature. We found a severe–mild wear transition phenomenon, which we called self-lubrication, and categorized friction behavior into two regimes: a high-friction regime and a low-friction regime. However, self-lubrication occurs only at specific strain levels and rates related to materials with martensite and pearlite structures. We characterized the microstructures of the worn surface, subsurface and matrix and found a thin self-lubricating layer composed of nano-oxide particles with sizes in the range 6–20 nm attached to the surface. The formation of these nano-oxide particles is controlled by lamellar structure (martensite or pearlite) nano-lamination, oxidation and solid-state amorphization during dry sliding. The high density of geometrically necessary dislocations and defects induced by plastic deformation under wear shear strain levels and rates is important in the formation of nano-lamellar microstructures and amorphous oxide. These results both clarify nano-lamellar microstructure solid-state amorphization and oxidation behavior and reveal the mechanism of self-lubricating layer formation observed in this work.
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