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Due to the limitation that natural peroxidase enzymes can only function in relatively mild environments, nanozymes have expanded the application of enzymology in the biological field by dint of their ability to maintain catalytic oxidative activity in relatively harsh environments. At the same time, the development of new and highly efficient composite nanozymes has been a challenge due to the limitations of monometallic particles in applications and the inherently poor enzyme-mimetic activity of composite nanozymes. The inherent enzyme-mimicking activity is due to Au, Ag, and Pt, along with other transition metals. Moreover, the nanomaterials exhibit excellent enzyme-mimicking activity when composited with other materials. Therefore, this paper focuses on composite nanozymes with simulated peroxidase activity that have been prepared using noble metals such as Au, Ag, and Pt and other transition metal nanoparticles in recent years. Their simulated enzymatic activity is utilized for biomedical applications such as glucose detection, cancer cell detection and tumor treatment, and antibacterial applications. [ABSTRACT FROM AUTHOR]

Compared to traditional actuators (such as piezoelectric ceramics), metal actuators possess the advantages of a low energy consumption, large strain amplitude, and high strain energy density. However, most of the existing metal actuators with an excellent comprehensive performance are composed of precious metals, which are limited by high costs and have almost no possibility for large-scale production in the future. This study focuses on non-precious metal materials and exploits a one-step chemical dealloying method to prepare bulk nanoporous (NP) CoCuAl actuators (NP-CCA) from Al70Co20Cu10 alloy. The microstructure and actuation properties of the NP-CCA were analyzed in detail. The dense continuous nanoscale pores provide an excellent network connectivity for a large strain response, enabling the NP-CCA to achieve a strain amplitude of up to 1.19% (more than eight and two times that of NP-Pt and NP-Ag, respectively), comparable to precious metal actuators. In addition, the NP-CCA possesses a high strain energy density, which is prominent in many precious metal actuation materials (such as NP-Au, NP-Ag, and NP-Pt). [ABSTRACT FROM AUTHOR]

Neuron-specific enolase (NSE) has gained extensive attention as a reliable target for detecting small cell carcinoma of lungs. In this paper, an electrochemical immunoassay method based on molybdenum disulfide (MoS2) is proposed to detect NSE sensitively. By an in-situ growth method, MoS2 and Au nanoclusters (Au NCs) were composited to form a MoS2@Au nanozyme, and then the secondary antibodies were modified. Primary antibodies were immobilized on amino-reduced graphene oxides to capture NSE. The flower-like MoS2 nanozyme provided abundant sites to load Au NCs and catalyze the decomposition of H2O2, which were beneficial to amplify an amperometric response as well as build up sensitivity. Under optimum conditions, the detection range of this strategy was 0.1 pg·mL−1–10 ng·mL−1 and the limit of detection was 0.05 pg·mL−1. This sensing strategy achieved the prospect of sensitively detecting NSE. Moreover, the prepared electrochemical immunosensor provides a theoretical basis and technical support for the detection of other disease markers. [ABSTRACT FROM AUTHOR]

The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose experiment, under construction in southeast China, that is designed to determine the neutrino mass ordering and precisely measure neutrino oscillation parameters. Monte Carlo simulation plays an important role for JUNO detector design, detector commissioning, offline data processing, and physics processing. The JUNO experiment has the world's largest liquid scintillator detector instrumented with many thousands of PMTs. The broad energy range of interest, long lifetime, and the large scale present data processing challenges across all areas. This paper describes the JUNO simulation software, highlighting the challenges of JUNO simulation and solutions to meet these challenges, including such issues as support for time-correlated analysis, event mixing, event correlation and handling the simulation of many millions of optical photons. [ABSTRACT FROM AUTHOR]

As an inflammatory marker, procalcitonin (PCT) is more representative than other traditional inflammatory markers. In this work, a highly efficient photoelectrochemical (PEC) immunosensor was constructed based on the photoactive material Bi2S3/Ag2S to realize the sensitive detection of PCT. Bi2S3 was prepared by a hydrothermal method, and Ag2S quantum dots were deposited on the ITO/Bi2S3 surface via in situ reduction. Bi2S3 is a kind of admirable photoelectric semiconductor nanomaterial on account of its moderate bandgap width and low binding rate of photogenerated electron holes, which can effectively convert light energy into electrical energy. Therefore, based on the energy level matching principle of Bi2S3 and Ag2S, a labeled Bi2S3/Ag2S PEC immunosensor was constructed, and the sensitive detection of PCT was successfully established. The linear detection range of the PEC immunosensor was 0.50 pg∙mL−1 to 50 ng∙mL−1, and the minimum detection limit was 0.18 pg∙mL−1. Compared with the traditional PEC strategy, the proposed PEC immunosensor is simple, convenient, and has good anti-interference, sensitivity, and specificity, which could provide a meaningful theoretical basis and reference value for the clinical detection of PCT. [ABSTRACT FROM AUTHOR]

It is critical to construct an accurate optical model of photomultiplier tubes (PMTs) in many applications to describe the angular and spectral responses of the photon detection efficiency (PDE) of the PMTs in their working media. In this study, we propose a new PMT optical model to describe both light interactions with the PMT window and optical processes inside PMTs with reasonable accuracy based on the optics theory and a GEANT4-based simulation toolkit. The proposed model builds a relationship between the PDE and the underlying processes that the PDE relies on. This model also provides a tool to transform the PDE measured in one working medium (like air) to the PDE in other media (like water, liquid scintillator, etc). Using two 20 ″ MCP-PMTs and one 20 ″ dynode PMT, we demonstrate a complete procedure to obtain the key parameters used in the model from experimental data, such as the optical properties of the antireflective coating and photocathode of the three PMTs. The proposed model can effectively reproduce the angular responses of the quantum efficiency of PMTs, even though an ideally uniform photocathode is assumed in the model. Interestingly, the proposed model predicts a similar level (20–30%) of light yield excess observed in the experimental data of many liquid scintillator-based neutrino detectors, compared with that predicted at the stage of detector design. However, this excess has never been explained, and the proposed PMT model provides a good explanation for it, which highlights the imperfections of PMT models used in their detector simulations. [ABSTRACT FROM AUTHOR]

The task of unsupervised anomalous sound detection (ASD) is challenging for detecting anomalous sounds from a large audio database without any annotated anomalous training data. Many unsupervised methods were proposed, but previous works have confirmed that the classification-based models far exceeds the unsupervised models in ASD. In this paper, we adopt two classification-based anomaly detection models: (1) Outlier classifier is to distinguish anomalous sounds or outliers from the normal; (2) ID classifier identifies anomalies using both the confidence of classification and the similarity of hidden embeddings. We conduct experiments in task 2 of DCASE 2020 challenge, and our ensemble method achieves an averaged area under the curve (AUC) of 95.82% and averaged partial AUC (pAUC) of 92.32%, which outperforms the state-of-the-art models. [ABSTRACT FROM AUTHOR]

In this study, a sensitive label-free electrochemical immunosensor was designed based on nanoporous Fe3O4 and a biotin–streptavidin system to specifically detect zearalenone (ZEN). Herein, nanoporous Fe3O4 was employed to carry streptavidin to prepare the highly sensitive immunosensor. The application of nanoporous Fe3O4 and the biotin–streptavidin reaction provided large amounts of antibodies on each conjugate, thus amplifying the detected signal. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were conducted to characterize the modification with ZEN. Factors which might influence the properties of the immunosensor, including concentration of nanoporous Fe3O4, pH of the buffer, incubation time and temperature were studied. Under the best conditions, the immunosensor displayed a highly sensitive response toward ZEN, ranging in concentration from 10.0 pg mL−1 to 3.00 ng mL−1 and 3.00 ng mL−1 to 12.0 ng mL−1, with a low detection limit of 3.7 pg mL−1. The results for analysis of human urine samples were satisfactory. Furthermore, this proposed method may find promising applications in the detection of other mycotoxins. [ABSTRACT FROM AUTHOR]

The classical geodesics of timelike particles in Schwarzschild spacetime is analyzed according to the particle starting radius r, velocity v and angle α against the radial outward direction in the reference frame of an local static observer. The region of escape, bound and capture orbits in the parameter space of (r , v , α) are solved using the three cases of the effective potential. It is found that generally for radius smaller than 4M or velocity larger than c / 2 there will be no bound orbits. While for fixed radius larger than 4M (or velocity smaller than c / 2 ), as velocity (or radius) increase from zero (or 2M), the particle is always captured until a critical value v crit 1 (or r crit 1 ) when the bound orbit start to appear around α = π / 2 between a double-napped cone structure. As the velocity (or radius) increases to another critical value v crit 2 (or r crit 2 ) then the bound directions and escape directions in the outward cone become escape directions, leaving only the inward cone separating the capture and bound directions. The angle of this cone will increase to its asymptotic value as velocity (or radius) increases to its asymptotic value. The implication of these results in shadow of black holes formed by massive particles, in black hole accretion and in spacecraft navigation is briefly discussed. [ABSTRACT FROM AUTHOR]

An ultrasensitive label-free photoelectrochemical (PEC) immunosensor was developed to detect amyloid β-protein (Aβ) based on CdS/CdTe-cosensitized SnO2 nanoflowers. Specifically, SnO2 with a flower-like porous nanostructure was utilized as a perfect substrate for the construction of PEC immunosensors, and the SnO2-modified electrode was first coated with CdTe quantum dots (QDs) and then further deposited with CdS by successive ionic layer adsorption and reaction techniques. The formed SnO2/CdS/CdTe-cosensitized structure exhibited excellent photocurrent intensity and was employed as an excellent photoactive matrix to immobilize Aβ antibody to further construct the immunosensor. Under optimal conditions, the as-constructed PEC immunosensor was used to detect Aβ and exhibited a wide linear concentration range from 0.5 pg mL−1 to 10 ng mL−1, with a low limit of detection (LOD, 0.18 pg mL−1, S/N = 3). Meanwhile, it also presented good reproducibility, specificity, and stability and may open a new promising platform for the clinical detection of Aβ or other biomarkers. [ABSTRACT FROM AUTHOR]

Background: Therapeutic glycoproteins have occupied an extremely important position in the market of biopharmaceuticals. N-Glycosylation of protein drugs facilitates them to maintain optimal conformations and affect their structural stabilities, serum half-lives and biological efficiencies. Thus homogeneous N-glycoproteins with defined N-glycans are essential in their application in clinic therapeutics. However, there still remain several obstacles to acquire homogeneous N-glycans, such as the high production costs induced by the universal utilization of mammalian cell expression systems, the non-humanized N-glycan structures and the N-glycosylation microheterogeneities between batches. Results: In this study, we constructed a Pichia pastoris (Komagataella phaffii) expression system producing truncated N-GlcNAc-modified recombinant proteins through introducing an ENGase isoform (Endo-T) which possesses powerful hydrolytic activities towards high-mannose type N-glycans. The results showed that the location of Endo-T in different subcellular fractions, such as Endoplasmic reticulum (ER), Golgi or cell membrane, affected their hydrolytic efficiencies. When the Endo-T was expressed in Golgi, the secreted IgG1-Fc region was efficiently produced with almost completely truncated N-glycans and the N-GlcNAc modification on the glycosite Asn297 was confirmed via Mass Spectrometry. Conclusion: This strategy develops a simple glycoengineered yeast expression system to produce N-GlcNAc modified proteins, which could be further extended to different N-glycan structures. This system would provide a prospective platform for mass production of increasing novel glycoprotein drugs. [ABSTRACT FROM AUTHOR]

Objective To explore the possible mechanism of Shen Shu Ning ( Kidney-tonifying and Liver-soothing Formula, SSN)in the intervention of HBV-induced HK-2 transdifferentiation and delay of renal interstitial fibrosis. Methods The drug-containing serum was prepared by intragastric administration of 75 C57BL/6 mice and models were made by using lipofectamineto transfect HBV to HK-2. The cells were divided into; blank serum control group, empty plasmid group, HBV group, benazepril group SSN ow concentration group SSN midd econcentration group and SSN high concentration group. The expressions of HBsAg, HBeAg, TGF-B1, pSmad2, pSmad3, Smad7, Col--II, Col IV and FN in HK-2 cells were detected by enzyme-linked immunosorbent assay (ELISA), real-time fluorescent quantitative PCR and Western blot. Results ELISA detection indicated that expressions of HBsAg, HBeAgandTGF-1were significantly increased in HBV group compared with the empty plasmid group (P < 0. 01). Compared with the HBV group, the expression of TGF-B1 protein was significantly decreased in the benazepril group SSN low concentration group SSN middle concentration group and SSN high concentration group( P <0.001 ) . Compared with the benazepril group thee xpresion of TGF-p1 in the SSN low concentration group was relatively high (P < 0. 05) ; qPCR detection showed that, compared with the HBV group, in the benapril group, and all SSN intervention groups the expressions of Col III, Col-IV and FN mRNA were significantly decreased (P <0.001). Western blot; Compared with the HBV group, the expressions of pSmad2 and pSmad3in the benazepril group and the SSN groups were significantly decreased (P < 0.001). Conclusion SSN could possibly alleviate HBV-induced transdifferentiation of human renal tubular epithelial cells and reduce the deposition of extracellular matrix by interfering with TGF-(51/Smad signaling pathway, thereby delaying the progression of fibrosis. [ABSTRACT FROM AUTHOR]

Food adhesion on containers could increase food waste and pollution; this problem can be effectively alleviated by introducing a superhydrophobic surface. In this research, edible superhydrophobic Fe foils (ESFFs) were prepared by fumigating edible low surface free energy substances including lard, beeswax, and food grade paraffin on calcined Fe foil. All of the three obtained ESFF samples exhibited excellent superhydrophobicity and attractive stability under different working conditions, and the used sample can be easily recovered by re-fumigation. Most tested liquid foods and starch slurries can be effectively repelled by ESFF without observable residues. The ESFF shows promising prospects as a green and useful superhydrophobic material. [ABSTRACT FROM AUTHOR]

A novel fluorescent turn-on aptasensor has been developed for the detection of mercuric ions (Hg2+) based on carbon dots (CDs) as donor molecules and MnO2 nanosheets as acceptor molecules. In this work, an effective fluorescent probe was fabricated through the conjugation of a single-stranded oligodeoxyribonucleotide (ssDNA) on the surface of CDs. In the absence of the target Hg2+, the CDs labeled with ssDNA were adsorbed on the MnO2 surface via van der Waals forces. The fluorescence signal of CDs was then quenched by MnO2 nanosheets via the fluorescence resonance energy transfer (FRET) mechanism. While Hg2+ was introduced, the specific affinity interactions between ssDNA and Hg2+ could detach CDs-labeled ssDNA (ssDNA-CDs) from the MnO2 surface because of the production of the thymine–Hg2+–thymine (T–Hg2+–T) complex, leading to the recovery of the fluorescence intensity. Under the optimal reaction conditions, the fluorescence intensity of CDs enhanced gradually with the increasing concentration of Hg2+ ions in the range from 2 to 200 nmol L−1 and the limit of detection was found to be 0.67 nmol L−1. In addition, the proposed strategy developed its application in the determination of Hg2+ in real samples with excellent performance. These features illustrated that the designed fluorescent sensing platform is a reliable quantitative candidate for potential applications in biological and analytical fields. [ABSTRACT FROM AUTHOR]

In the version of this article initially published, there was only one author marked as corresponding author. Since Ziyan Deng and Guofu Cao have almost equal contributions to the development of the JUNO simulation software, so making both Ziyan Deng and Guofu Cao as the corresponding authors can correctly reflect the contributions in this work. [Extracted from the article]

Herein, we demonstrated the protocol of a visible light induced photoelectrochemical cytoassay on the basis of TiO2 nanorods/carboxylated g-C3N4/ox-graphene quantum dots coupling with a biospecific interaction for the ultrasensitive detection of fibroblast-like synoviocyte cells. The nanohybridization assembly of TiO2 NRs, carboxylated g-C3N4 and ox-GQDs showed good PEC performance through the excellent electrical conductivity as well as the high photon-to-electron conversion efficiency and improved the sensitivity of the cytosensor. To perform the cytoassay, CD95 antibody, a marker of FLS cells, was conjugated onto the TiO2 NR/carboxylated g-C3N4/ox-GQD modified electrode to trap the cell target by using EDC/NHS coupling reactions. The concentrations of FLS cells were determined by the decrease in photocurrent intensity resulting from the increase in steric hindrance from FLS cells. This strategy opens a simple perspective for the application of carboxylated g-C3N4 and ox-GQDs as light-harvesting architectures. [ABSTRACT FROM AUTHOR]

Together with the big datamovement,many organizations collect their own big data and build distinctive applications. In order to provide smart services upon big data, massive variable data should be well linked and organized to form Data Ocean, which specially emphasizes the deep exploration of the relationships among unstructured data to support smart services. Currently, almost all of these applications have to deal with unstructured data by integrating various analysis and search techniques upon massive storage and processing infrastructure at the application level, which greatly increase the difficulty and cost of application development. This paper presents D-Ocean, an unstructured data management system for data ocean environment. D-Ocean has an open and scalable architecture, which consists of a core platform, pluggable components and auxiliary tools. It exploits a unified storage framework to store data in different kinds of data stores, integrates batch and incremental processing mechanisms to process unstructured data, and provides a combined search engine to conduct compound queries. Furthermore, a so-called RAISE process modeling is proposed to support the whole process of Repository, Analysis, Index, Search and Environment modeling, which can greatly simplify application development. The experiments and use cases in production demonstrate the efficiency and usability of D-Ocean. [ABSTRACT FROM AUTHOR]

Magnetic hydroxypropyl chitosan/graphene oxide (MHCGO) composites have been synthesized and employed as adsorbent for removal of lead ions from aqueous solution. X-ray powder diffraction, Fourier transform infrared spectrum, and scanning electron microscope showed that the MHCGO composites were fabricated successfully. The effects of adsorbent dosage, pH, and contact time on the adsorption of lead ions have been discussed, and the optimal adsorption conditions have been acquired. The results indicated that the adsorption of lead ions on MHCGO was dependent on pH with the optimum pH nearly 5.5. The adsorption process was fairly quick and the time to reach adsorption equilibrium is 100 min. The adsorption kinetics could be described by the pseudo-second-order model very well. Adsorption data fitted well with Freundlich model. The effect of temperature on lead ions adsorption was studied and was shown to be spontaneous. [ABSTRACT FROM PUBLISHER]

The MapReduce framework has become the de facto standard for big data processing due to its attractive features and abilities. One is that it automatically parallelizes a job into multiple tasks and transparently handles task execution on a large cluster of commodity machines. The increasing heterogeneity of distributed environments may result in a few straggling tasks, which prolong job completion. Speculative execution is proposed to mitigate stragglers. However, the existing speculative execution mechanism could not work efficiently as many speculative tasks are still slower than their original tasks. In this paper, we explore an approach to increase the efficiency of speculative execution, and further improve MapReduce performance. We propose the Partial Speculative Execution (PSE) strategy to make speculative tasks start from the checkpoint. By leveraging the checkpoint of original tasks, PSE can eliminate the costs of re-reading, re-copying, and re-computing the processed data. We implement PSE in Hadoop, and evaluate its performance in terms of job completion time and the efficiency of speculative execution under several kinds of classical workloads. Experimental results show that, in heterogeneous environments with stragglers, PSE completes jobs 56 % faster than that with no speculation and 12 % faster than that with LATE, an improved speculative execution algorithm. In addition, on average PSE can improve the efficiency of speculative execution by 24 % compared to LATE. [ABSTRACT FROM AUTHOR]

An ultrasensitive electrochemical immunosensor for the detection of cluster of differentiation 146 antigen (CD146) based on TiO2 colloidal sphere laden Au/Pd nanoparticles (Au/Pd@TiO2) was developed. In this work, reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) was applied as an electrode modifying material to modify the surface of a glassy carbon electrode (GCE). Au/Pd@TiO2 was used as the secondary-antibody (Ab2) label for the fabrication of the immunosensor. Amperometric response of the immunosensor for electrocatalytic reduction of hydrogen peroxide (H2O2) was recorded. Electrochemical impedance spectroscopy (EIS) proved that fabrication of the immunosensor was successful. The anti-CD146 primary antibody (Ab1) was immobilized on the rGO-TEPA modified GCE by a cross-linking reagent of glutaraldehyde (GA). With Ab1 immobilized onto the rGO-TEPA modified GCE and Ab2 linked with Au/Pd@TiO2, the immunosensor displayed a wide linear range (0.0050–20 ng mL−1), a low detection limit (1.6 pg mL−1), good reproducibility, good selectivity and acceptable stability. The designed sensing strategy may provide a potential application in the detection of other tumor markers. [ABSTRACT FROM AUTHOR]

In this paper, carboxymethyl functionalized chitosan was used for the synthesis of a magnetic polysaccharide–graphene oxide composite (SCGO). Compared with the magnetic chitosan–graphene oxide composite reported before, adsorption capacity in this research had improved significantly. The calculated maximum adsorption capacity values for methylene blue (MB) and malachite green (MG) were 358.4 mg g−1 and 289.1 mg g−1, respectively. The morphology, chemical properties and physical structure of SCGO were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). The influence factors which included pH, adsorbent dose, ionic strength and contact time on the adsorption properties of MB and MG onto SCGO were investigated. The adsorption kinetics of MB and MG on SCGO were well-described by pseudo-second order kinetic models. The experimental data of the isotherm followed the Temkin isotherm model and the Langmuir model, respectively. Thermodynamic analysis was also performed to calculate the changes in free energy (ΔG), enthalpy (ΔH), and entropy (ΔS). The results obtained from this research suggested that SCGO was a potential adsorbent for effective removal of methylene blue and malachite green. [ABSTRACT FROM AUTHOR]

The excellent catalytic activity of a novel nanomaterial was introduced to ultrasensitive sandwich-type electrochemical immunosensor applications for detection of carcinoembryonic antigen (CEA). Amino-functionalized multi-walled carbon nanotube (MWCNT-NH2) supported PdPt nanocages were used as catalytic labels of secondary anti-CEA. PdPt nanocages with hollow interiors and porous walls could efficiently enhance electrocatalysis for reduction of H2O2. Meanwhile, with good dispersion, large specific surface area and amino groups, MWCNT-NH2 can immobilize a large amount of PdPt nanocages to improve the sensitivity and amplify the signal of the immunosensor. For the immobilization of primary antibodies, 3-aminopropyltriethoxysilane functionalized graphene sheets were used as transducing materials to modify glassy carbon electrodes and to enhance the electron transfer efficiently. Under the optimal conditions, the electrochemical immunosensor exhibited a wide linear range of 0.001–20 ng mL−1 with a low detection limit of 0.2 pg mL−1 for CEA. The proposed sensing strategy enriches electrochemical immunoassays and may have a promising application in bioassay analysis. [ABSTRACT FROM AUTHOR]

A sandwich-type immunosensor was developed for the detection of human tissue polypeptide antigen (hTPA). In this work, a graphene sheet (GS) was synthesized to modify the surface of a glassy carbon electrode (GCE), and Pd–Pt bimetallic nanocrystals were used as secondary-antibody (Ab2) labels for the fabrication of the immunosensor. The amperometric response of the immunosensor for catalyzing hydrogen peroxide (H2O2) was recorded. And electrochemical impedance spectroscopy was used to characterize the fabrication process of the immunosensor. The anti-human tissue polypeptide antigen primary antibody (Ab1) was immobilized onto the GS modified GCE via cross-linking with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide (EDC/NHS). With Ab1 immobilized onto the GS modified GCE and Ab2 linked on Pd–Pt bimetallic nanocrystals, the immunosensor demonstrated a wide linear range (0.0050–15 ng ml−1), a low detection limit (1.2 pg ml−1), good reproducibility, good selectivity and acceptable stability. This design strategy may provide many potential applications in the detection of other cancer biomarkers. [ABSTRACT FROM AUTHOR]

The metabolic process of the human body produces a large number of gaseous biomarkers. The tracking and monitoring of certain diseases can be achieved through the detection of these markers. Due to the superior specific surface area, large functional groups, good optical transparency, conductivity and interlayer spacing, graphene, and its derivatives are widely used in gas sensing. Herein, the development of graphene and its derivatives in gas-phase biomarker detection was reviewed in terms of the detection principle and the latest detection methods and applications in several common gases, etc. Finally, we summarized the commonly used materials, preparation methods, response mechanisms for NO, NH3, H2S, and volatile organic gas VOCs, and other gas detection, and proposed the challenges and prospective applications in this field. [ABSTRACT FROM AUTHOR]

Based on the necessity and urgency of detecting infectious disease marker procalcitonin (PCT), a novel unlabeled photoelectrochemical (PEC) immunosensor was prepared for the rapid and sensitive detection of PCT. Firstly, SnO2 porous nanoflowers with good photocatalytic performance were prepared by combining hydrothermal synthesis and calcining. BiOI nanoflowers were synthesized by facile ultrasonic mixed reaction. Ag2S quantum dots were deposited on SnO2/BiOI composites by in situ growth method. The SnO2/BiOI/Ag2S composites with excellent photoelectric properties were employed as substrate material, which could provide significantly enhanced and stable signal because of the energy level matching of SnO2, BiOI and Ag2S and the good light absorption performance. Accordingly, a PEC immunosensor based on SnO2/BiOI/Ag2S was constructed by using the layered modification method to achieve high sensitivity analysis of PCT. The linear dynamic range of the detection method was 0.50 pg·mL−1~100 ng·mL−1, and the detection limit was 0.14 pg·mL−1. In addition, the designed PEC immunosensor exhibited satisfactory sensitivity, selectivity, stability and repeatability, which opened up a new avenue for the analyzation of PCT and further provided guidance for antibiotic therapy. [ABSTRACT FROM AUTHOR]

We consider the scheduling problem of minimizing the average weighted completion time of n jobs with release dates on a single machine. We first study two linear programming relaxations of the problem, one based on a time-indexed formulation, the other on a completion- time formulation. We show their equivalence by proving that a O (n log n) greedy algorithm leads to optimal solutions to both relaxations. The proof relies on the notion of mean busy times of jobs, a concept which enhances our understanding of these LP relaxations. Based on the greedy solution, we describe two simple randomized approximation algorithms, which are guaranteed to deliver feasible schedules with expected objective function value within factors of 1.7451 and 1.6853, respectively, of the optimum. They are based on the concept of common and independent α-points, respectively. The analysis implies in particular that the worst-case relative error of the LP relaxations is at most 1.6853, and we provide instances showing that it is at least e/(e - 1) &ap; 1.5819. Both algorithms may be derandomized; their deterministic versions run in O(n²) time. The randomized algorithms also apply to the on-line setting, in which jobs arrive dynamically over time and one must decide which job to process without knowledge of jobs that will be released afterwards. [ABSTRACT FROM AUTHOR]

Enzyme-histochemical demonstration of lymphatic vessels in the golden hamster periodontium was performed on cryostat sections using the 5'-nucleotidase (5'-Nase) staining method by light microscopy and backscattered electron imaging of scanning electron microscopy. The inhibition of the 5'-Nase activity by decalcification was cancelled by the Mg++ ion supply. The reaction products of 5'-Nase activity were produced on the lymphatic endothelial cells and the tubular structures of lymphatic vessels were seen as highlights by backscattered electron imaging. The invasion of 5'-Nasepositive lymphatic vessels into the alveolar bone from the periodontium was found in the present study. [ABSTRACT FROM PUBLISHER]

Abstract. The optimal k-restricted 2-factor problem consists of finding, in a complete undirected graph K[sub n] a minimum cost 2-factor (subgraph having degree 2 at every node) with all components having more than k nodes. The problem is a relaxation of the well-known symmetric travelling salesman problem, and is equivalent to it when n/2 Is less than or equal to k Is less than or equal to n - 1. We study the k-restricted 2-factor polytope. We present a large class of valid inequalities, called bipartition inequalities, and describe some of their properties; some of these results are new even for the travelling salesman polytope. For the case k = 3, the triangle-free 2-factor polytope, we derive a necessary and sufficient condition for such inequalities to be facet inducing. [ABSTRACT FROM AUTHOR]

Lead ion (Pb2+) has high toxicity and brings great harm to human body. It is very important to find an effective method to address lead ion pollution. In this work, amino functionalized CoFe2O4/SBA–15 nanocomposite (NH2–CoFe2O4/SBA–15) was prepared for the effective removal of Pb2+ from aqueous solution. The prepared NH2–CoFe2O4/SBA–15 adsorbent was manifested by using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectrum (FTIR), X-ray powder diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis. In the meantime, the adsorption conditions, including pH, adsorbent dosage, and adsorption time, were studied. The investigation of adsorption kinetics revealed that the adsorption results conform to the pseudo-first-order kinetic model. The adsorption isotherms research displayed that the adsorption was consistent with the Freundlich model, demonstrating that the adsorption for Pb2+ with the prepared adsorbent was a multimolecular layer adsorption process. In addition, the thermodynamic investigations (ΔG < 0, ΔH > 0, ΔS > 0) demonstrated that the adsorption for Pb2+ with the prepared adsorbent was endothermic and spontaneous. Moreover, the prepared adsorbent showed superior anti-interference performance and reusability, implying the potential application of the adsorbent in actual water treatment. Furthermore, this research may provide a reference and basis for the study of other heavy metal ions. [ABSTRACT FROM AUTHOR]

The Asymmetric Travelling Salesman (ATS) polytope ATSP(V) is the convex hull of incidence vectors of all Hamiltonian circuits in a complete digraph with node set V. This paper studies classes of valid symmetric inequalities ay ≤ a0 for ATS polytopes with coefficients satisfying aij = aji for all pair of cities i and j. Of particular interest are those inequalities derived from facet-defining inequalities for Symmetric Travelling Salesman Polytopes (STSPs). We show that known classes of STSP facet-defining inequalities, such as Path, Wheelbarrow, Chain, and Ladder inequalities, induce symmetric ATSP facet-defining inequalities. For ATSP(V) with &verbar;V&verbar; ≤ 8, we show that there are precisely four types of STSP facet-defining inequalities that do not induce ATSP facets. We propose a Tree Composition of symmetric inequalities and use it to generate a large new class of symmetric facet-defining inequalities for ATS polytopes, subsuming all nonspanning Clique Tree inequalities. A Hamiltonian path approach is used for most of the polyhedral proofs in the paper. [ABSTRACT FROM AUTHOR]

The permutahedron of a poset is the convex hull of all incidence vectors of linear extensions. For the case of N-sparse posets in which any five elements induce at most one N we give a characterization of the permutahedron in terms of linear inequalities. This yields an LP-solution for minimizing the weighted mean completion time for jobs with unit processing times and N-sparse precedence constraints. We close with an extension of our approach to arbitrary processing times. [ABSTRACT FROM AUTHOR]

We introduce a projective approach for studying symmetric travelling salesman polytopes (STSPs). The symmetric travelling salesman polytope STSP( V) (resp., Hamiltonian path polytope HP( V)) is the convex hull of incidence vectors of all Hamiltonian cycles (resp., paths) on the complete undirected graph with node set V. For any node h ∉ V, HP( V) is a projection of STSP( V ⋃ { h}). We show that HP( V) and STSP( V ⋃ { h}) are isomorphic, and HP( V) is of full dimension minus one. By this projective approach, we obtain general clique-lifting results, all based on simple conditions, for deriving large new classes of STSP facets. These results apply to all known non-trivial STSP facets, and generalize clique-lifting results of Maurras (1975), Grötschel and Padberg (1979) and Naddef and Rinaldi (1988). [ABSTRACT FROM AUTHOR]

Self-supported Fe3N-Co2N nanoarray with high electric conductivity and large surface area was prepared for growth of MIPs and further constructing a sensitive and stable electrochemical sensor. For the evaluation of its performance, Fe3N-Co2N is used as sensing electrode material, and AMP is used as template molecule to construct the MIP electrochemical sensor. Under the optimized conditions, the developed MIPs electrochemical sensor detects AMP with a low detection limit of 3.65 × 10−10 mol L−1 and shows outstanding reproducibility and stability. When the MIPs electrochemical sensor was applied to detect AMP in milk samples via standard addition method, the recovery within 97.06–102.43% with RSD of 1.05–2.11% was obtained. The fabrication of MIPs electrochemical sensor is highly promising for sensitive and selective electrochemical measurement and food safety testing. This work can provide theoretical guidance for truly challenging problems. [ABSTRACT FROM AUTHOR]

The existence and stability of circular orbits (CO) in static and spherically symmetric (SSS) spacetime are important because of their practical and potential usefulness. In this paper, using the fixed point method, we first prove a necessary and sufficient condition on the metric function for the existence of timelike COs in SSS spacetimes. After analyzing the asymptotic behavior of the metric, we then show that asymptotic flat SSS spacetime that corresponds to a negative Newtonian potential at large r will always allow the existence of CO. The stability of the CO in a general SSS spacetime is then studied using the Lyapunov exponent method. Two sufficient conditions on the (in)stability of the COs are obtained. For null geodesics, a sufficient condition on the metric function for the (in)stability of null CO is also obtained. We then illustrate one powerful application of these results by showing that three SSS spacetimes whose metric function is not completely known will allow the existence of timelike and/or null COs. We also used our results to assert the existence and (in)stabilities of a number of known SSS metrics. [ABSTRACT FROM AUTHOR]

In this work, a novel label-free electrochemical immunosensor was developed for the quantitative detection of alpha fetoprotein (AFP). Multifunctionalized graphene nanocomposites (TB-Au-Fe3O4-rGO) were applied to modify the electrode to achieve the amplification of electrochemical signal. TB-Au-Fe3O4-rGO includes the advantages of graphene, ferroferric oxide nanoparticles (Fe3O4 NPs), gold nanoparticles (Au NPs) and toluidine blue (TB). As a kind of redox probe, TB can produce the electrochemical signal. Graphene owns large specific surface area, high electrical conductivity and good adsorption property to load a large number of TB. Fe3O4 NPs have good electrocatalytic performance towards the redox of TB. Au NPs have good biocompatibility to capture the antibodies. Due to the good electrochemical performance of TB-Au-Fe3O4-rGO, the effective and sensitive detection of AFP was achieved by the designed electrochemical immunosensor. Under optimal conditions, the designed immunosensor exhibited a wide linear range from 1.0 × 10−5 ng/mL to 10.0 ng/mL with a low detection limit of 2.7 fg/mL for AFP. It also displayed good electrochemical performance including good reproducibility, selectivity and stability, which would provide potential applications in the clinical diagnosis of other tumor markers. [ABSTRACT FROM AUTHOR]