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A facile dual-mode sensor based on CuO nanorod-decorated hemin-graphene was constructed for the detection of 4-aminophenol (4-AP). In addition, a smartphone-based assay was developed, which opened a new path for the on-site detection of 4-AP.

Based on DFT matrices and no-hit-zone (NHZ) frequency hopping sequence sets, a construction of multiple optimal polyphase zero correlation zone sequence sets with inter-set zero cross-correlation zone (ZCCZ) is proposed. The parameters of each subset are optimal, and arbitrary two sequences from different subsets have the same inter-set ZCCZ. Furthermore, new NHZ frequency hopping sequence sets are proposed, which can be used in the construction of multiple polyphase ZCZ sequence sets with inter-set ZCCZ. The resultant sequence sets presented in this letter can be applied to multi-cell QS-CDMA systems.

Background and Purpose: The defective colonic mucus barrier is a feature of ulcerative colitis (UC) that enables increased bacterial contact with the epithelium, which triggers mucosal damage, and gastrin has been reported to be able to promote healing through the cholecystokinin 2 receptor (CCK2R) signaling to increase epithelial regeneration and protect against colonic injury. However, the role of gastrin in UC remains unclear. Experimental Approach: Colonic samples from human sections and mouse models using β-arrestin1 wild-type (β-arr1-WT) and β-arrestin1 knockout (β-arr1-KO) littermates, intestinal epithelial cells specific NF-κBp65 deletion (NF-κBp65) and wild-type (NF-κBp65) mice were analyzed. The mucosal injury, goblet cells status, MUC2 expression and bacteria penetration/colonisation were examined, and the effect of gastrin in colitis was also investigated. Key Results: We demonstrate that mucus barrier loss and bacterial colonisation of the crypts were observed in colitis, and exogenous gastrin could restore the mucus barrier, reduce bacterial colonisation of the colonic crypts and alleviate colitis via CCK2R. Furthermore, targeting CCK2R by YF476, β-arrestin1 (β-arr1) deletion or intestinal epithelial NF-κBp65 deficiency breached gastrin-mediated mucus barrier restoration and mucosal protection in colitis. Conclusion and Implications: These data demonstrate that gastrin alleviates mucus barrier loss and bacterial colonisation of the colonic crypts via CCK2R/β-arr1/NF-κBp65 signaling in colitis, and this network may be a potential therapeutic target for UC.

Background The aging small intestine has a great impact on body health. One of the obvious characteristics is the degeneration of epithelium turnover. The acknowledged Lgr5+ intestinal stem cell is the key factor. Methods We used Lgr5-EGFP transgenic mice in three different ages (young group:3-6 months, middle group:12-14 months and old group:22-24 months) to mark the Lgr5+ISCs. We collected the jejunum for histology, immunofluorescence, western-blotting and PCR, we isolated the crypts for organoid culture and sorted out the Lgr5hi cells for bulk RNA sequence. Results In tissue, the crypts depth, proliferating cells and Lgr5+ISCs number increased in middle group (12-14 months) and then decreased in old group (22-24 months). The number of proliferating Lgr5+ISCs gradually decreased from young to old. In organoids, the buddings number and projected area, Lgr5+ISCs ratio also decreased from young to old. Both gene expression of Parp3 and protein level of Parp3 increased in middle and old group. Parp3 inhibitors slowed down organoids’ growth of the middle age. Conclusion Parp3 might participate in regulating the proliferation capacity of Lgr5+ISCs during aging.

Pd-Pt bimetallic nanocrystals have become appealing in the electrocatalytic field by virtue of their synergy effects derived from the electronic coupling between two metals. Herein, a facile seed-mediated growth approach is reported for synthesis of Pt-on-Pd dendritic nanosheets (DNSs) through the growth of Pt branches on ultrathin Pd nanosheets (NSs). The as-obtained Pt-on-Pd DNSs exhibit superior catalytic activity toward both oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR), with mass activities (MAs) 2.2 times higher for ORR and 3.4 times higher for MOR than commercial Pt/C catalysts. Moreover, these spatially separated Pt branches supported on 2D NSs also endow the Pt-on-Pd DNSs with impressive durability for ORR with only 18.9% loss in MA, whereas the Pt/C catalyst loses 50.0% after 10,000-cycle accelerated durability tests. This 2D DNS architecture can be extended to other 2D metallic NS substrates for constructing Pt-based electrocatalysts with excellent electrocatalytic performance.

In this work, two-dimensional magnetic chitosan nanosheets (CSMNSs) for azo dye adsorption were successfully synthesised by a simple hydrothermal method. The as-prepared CSMNSs was characterised by scanning electron microscope, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and vibrating sample magnetometer. Then, the CSMNSs as the dye adsorbent were applied to the removal of two kinds of azo dyes (methyl orange and amido black). The effect of solution pH and adsorbent dosage, adsorption isotherm, adsorption kinetics and the reusability of CSMNSs were examined. Adsorption isotherms obeyed Freundlich model and adsorption kinetics was described as pseudo-second-order model. Furthermore, the CSMNSs have the advantage of simple synthesis route, high absorption efficiency, rapid magnetic separation from aqueous solutions and excellent reusability. The CSMNSs as the dye adsorbent was applied to removal of azo dyes with broad prospects.

MXenes as a new class of 2D materials have recently been widely applied in energy storage, electrocatalysis, sensors, adsorption, water purification, and so on, due to their tunable versatile properties. Herein, we demonstrate a simple, rapid and highly-sensitive sensing platform based on ultrathin two-dimensional MXene Ti3C2 nanosheets (Ti3C2 NSs) for selective analysis of Human papillomavirus (HPV), a major human pathogens and causative agents of cervical cancer. Ultrathin Ti3C2 NSs, obtained by exfoliating their layered HF-etched powder, exhibit high fluorescence quenching ability to dye-labeled single-stranded DNA (ssDNA) and different affinities for ssDNA and double-stranded DNA (dsDNA). Under the fluorescence quenching effect of Ti3C2 NSs, ssDNA probe (P) shows the minimal fluorescent emission. After the formation of duplex structure with its complementary target, ssDNA (T), the fluorescence intensity enhances evidently. Exonuclease III (Exo III) was used to improve the sensitivity by promoting more fluorescence enhancement. This magnified fluorescent sensor for HPV-18 detection shows a low detection limit of 100 pM and a high specificity. Furthermore, the developed DNA sensor can be employed to determine PCR amplified HPV-18 from cervical scrapes samples. It highlights ultrathin Ti3C2 NSs as a potential candidate for construction of fluorescence DNA biosensors with excellent performances.

N-Nitrosodiphenylamine (NDPhA), a typically nonvolatile N-nitrosamine (NA), is widely used as an additive in daily human necessities and is considered as a possible cancer-causing substance by the US Environmental Protection Agency. Therefore, the determination of NDPhA in environment is crucial to people's health. In this study, a simple and high-performance electrochemical sensor for NDPhA detection is constructed based on poly(diallyldimethylammonium chloride)-stabilized graphene/platinum nanoparticles (PDDA–Gr/PtNPs) as an electrochemical sensing platform. The PDDA–Gr/PtNP nanocomposite is synthesized by a facile wet-chemical approach. It combines the prominent properties of graphene (large surface areas and high conductivity) with the outstanding catalytic activity of Pt nanoparticles. Because of its remarkable synergistic effect, a PDDA–Gr/PtNP-modified glassy carbon electrode (PDDA–Gr/PtNPs/GCE) shows excellent performance towards electrooxidation of NDPhA with a significantly increased peak current and negatively shifted peak potential compared to graphene-modified electrode (PDDA–Gr/GCE); it exhibits good linearity for NDPhA detection with a linear range of 1.0 × 10−7–5.0 × 10−5 mol L−1 and a detection limit of 3.3 × 10−8 mol L−1 (S/N = 3) under optimum conditions. Moreover, this cost-effective and convenient sensor also has good stability, repeatability and anti-interference ability and is promising for trace analysis of NAs in environmental pollutants.

MXenes are attractive for various biosensors owning to their tunable versatile properties. Herein, Ti3C2 nanosheets (Ti3C2 NSs) were found to possess intrinsic peroxidase-like activity, and which could be enhanced by single-stranded DNA (ssDNA) adsorbed on the nanosheets. Hence, a simple label-free sensing strategy was developed for colorimetric detection of biomolecules, based on Ti3C2 NSs as a peroxidase mimic enzyme and ssDNA aptamer as an enzymatic activity enhancement factor along with a recognition substance for the target. In the presence of target biomolecules, the aptamers were desorbed from Ti3C2 NSs due to the specific binding of targets to aptamers, thus bringing about the decrease of catalytic activity. Thrombin (TB) as the model was determined by this constructed biosensor with a linear range of 1.0 × 10−11 to 1.0 × 10−8 M, and evaluated subsequently in the real blood samples with satisfactory results. This work highlights Ti3C2 MXenes as a nanomaterial mimic enzyme (called nanozyme) for monitoring biomolecules by target-specific recognition strategy.

When the Anti-Spoofing (A-S) is active, the civilian users have some difficulties in using the P(Y) code for precise navigation and positioning. Z-tracking technique is one of the effective methods to acquire the P(Y) code. In this paper, the accuracy of pseudoranges from C/A code and P(Y) code for dual frequency GPS receiver is discussed. The principle of measuring the encrypted P(Y) code is described firstly, then a large data set from IGS tracking stations is utilized for analysis and verification with the help of a precise point positioning software developed by authors. Especially, P(Y) code pseudoranges of civilian GPS receivers allow eliminating/reducing the effect of ionospheric delay and improve the precision of positioning. The point positioning experiments for this are made in the end.

ARCE (Ambiguity Resolution Using Constraint Equation) is a new fast method to resolve the integer ambiguities based on LSE (Least-Squares Estimate) and null space, which is suitable for single frequency GPS receivers and whose necessary observation time span of fixing the integer ambiguities correctly is relatively long (say, at least one minute). In this paper, ARCE is improved for deformation monitoring when there is only one epoch phase observation. In this instance, the normal matrix is rank-deficient and it is impossible to fix the integer ambiguities correctly using ARCE if LSE is employed. In allusion to the above case, based on Tikhonov regularization theorem, a new regularizer is designed to transform the rank-deficient normal matrix to a full rank one. The accurate float ambiguity solutions are obtained and the corresponding search range of the integer ambiguities diminishes. So, the integer ambiguities can be fixed using ARCE. The effect of the single epoch algorithm is tested utilizing a baseline whose length over 3KM and the results show that the success rate of fixing the integer ambiguities using the new algorithm can achieve to over 90 percent.