Luminescent carbon dots-rooted polysaccharide crosslinked hydrogel adsorbent for sensitive determination and efficient removal of Cu2.

In this study, a novel luminescent carbon dot-rooted polysaccharide hydrogel (CDs@CCP hydrogel) was prepared by crosslinking cellulose, chitosan (CS), and polyvinyl alcohol (PVA) for simultaneous fluorescent sensing and adsorption of Cu2+. The crosslinking of these low-cost, polysaccharide polymers greatly enhance the mechanical strength of the composite hydrogel while making the polysaccharide-based adsorbent easy to reuse. This composite hydrogel exhibited an excellent adsorption capacity (124.7 mg∙g-1) for residual Cu2+ in water, as well as a sensitive and selective fluorescence response towards Cu2+ with a good linear relationship (R2 > 0.97) and a low detection limit (LOD) of 0.02 µM. The adsorption isotherms, adsorption kinetics, and thermodynamics studies were also conducted to investigate the adsorption mechanism. This composite hydrogel offers an efficient tool for simultaneous monitoring and treatment of Cu2+ from wastewater.

Corrigendum: Study of quality of life and its correlated factors in patients after lumbar fusion for lumbar degenerative disc disease.

[This corrects the article DOI: 10.3389/fsurg.2022.939591.].

Integrative physiological, critical plant endogenous hormones, and transcriptomic analyses reveal the difenoconazole stress response mechanism in wheat (Triticum aestivum L.).

Difenoconazole (DFN) is widely utilized as a fungicide in wheat production. However, its accumulation in plant tissues has a profound impact on the physiological functions of wheat plants, thus severely threatening wheat growth and even jeopardizing human health. This study aims to comprehensively analyze the dynamic dissipation patterns of DFN, along with an investigation into the physiological, hormonal, and transcriptomic responses of wheat seedlings exposed to DFN. The results demonstrated that exposure of wheat roots to DFN (10 mg/kg in soil) led to a significant accumulation of DFN in wheat plants, with the DFN content in roots being notably higher than that in leaves. Accumulating DFN triggered an increase in reactive oxygen species content, malonaldehyde content, and antioxidant enzyme activities, while concurrently inhibiting photosynthesis. Transcriptome analysis further revealed that the number of differentially expressed genes was greater in roots compared with leaves under DFN stress. Key genes in roots and leaves that exhibited a positive response to DFN-induced stress were identified through weighted gene co-expression network analysis. Metabolic pathway analysis indicated that these key genes mainly encode proteins involved in glutathione metabolism, plant hormone signaling, amino acid metabolism, and detoxification/defense pathways. Further results indicated that abscisic acid and salicylic acid play vital roles in the detoxification of leaf and root DFN, respectively. In brief, the abovementioned findings contribute to a deeper understanding of the detrimental effects of DFN on wheat seedlings, while shedding light on the molecular mechanisms underlying the responses of wheat root and leaves to DFN exposure.

Covalent organic framework-based magnetic solid-phase extraction coupled with gas chromatography-tandem mass spectrometry for the determination of trace phthalate esters in liquid foods.

Covalent organic framework-coated magnetite particles (Fe3O4@COF) were synthesized and applied as the adsorbent to the selective capture of phthalate esters (PAEs) in liquid foods. Combined with the magnetic solid-phase extraction (MSPE) technology, a gas chromatography-tandem mass spectrometry (GC-MS/MS) method was employed for the separation and quantification of PAEs. Following optimization of the magnetic extraction and elution parameters, the developed analytical method offered a satisfactory linear range (0.1-5 µg L-1) with determination coefficients ranging from 0.9934 to 0.9975 for the five different PAEs studied. The limits of detection (LOD) were in the range 1.9-12.8 ng L-1. The recoveries ranged from 70.0 to 119.8% with a relative standard deviation (RSD) less than 9.7%. Density functional theory (DFT) calculations established that the dominant adsorption mechanism used by the COF to bind PAEs involved π-π stacking interactions. Results encourage the wider use of COF-based adsorbents and MSPE methods in the analytical determination of PAEs in foods.

Physcion and chitosan-Oligosaccharide (COS) synergistically improve the yield by enhancing photosynthetic efficiency and resilience in wheat (Triticum aestivum L.).

As progressively increasing food safety concerns, diversified plant diseases and abiotic stresses, environmental-friendly bio-pesticides and bio-stimulants combinations may are likely to serve as a vital means of safeguarding green and sustainable food production. Accordingly, in this study, pot and field trials were performed to examine the application potential of the combination of physcion and chitosan-Oligosaccharide (COS) in wheat production. Wheat seeds were coated with physcion and COS and the effects exerted by them on morphology, physiology and yield of the wheat were investigated. As indicated by the results, the combination of physcion and COS not only did not inhibit the growth of wheat seedlings, but also synergistically increased root vigor and photosynthetic pigment content. Simultaneously, the lignin content in the roots and leaves was increased significantly. Moreover, the result confirmed that the combination of both substances reduced the MDA content, which was correlated with the up-regulation of the transcript expression level of antioxidant enzyme genes and the resulting increased enzyme activity. Furthermore, this combination synergistically increased the net photosynthetic rate (Pn) of the flag leaves and ultimately contributed to the increase in yield. Notably, the above-mentioned desirable cooperative effect was not limited by cultivars and cultivation methods. The conclusion of this study suggested that the combination of physcion and COS synergistically improved the photosynthetic rate and resilience in wheat, such that high wheat yields can be more significantly maintained, and future food security can be more effectively ensured.

Effect of Y Content on Precipitation Behavior, Oxidation and Mechanical Properties of As-Cast High-Temperature Titanium Alloys.

To improve the heat resistance of titanium alloys, the effects of Y content on the precipitation behavior, oxidation resistance and high-temperature mechanical properties of as-cast Ti-5Al-2.75Sn-3Zr-1.5Mo-0.45Si-1W-2Nb-xY (x = 0.1, 0.2, 0.4) alloys were systematically investigated. The microstructures, phase evolution and oxidation scales were characterized by XRD, Laser Raman, XPS, SEM and TEM. The properties were studied by cyclic oxidation as well as room- and high-temperature tensile testing. The results show that the microstructures of the alloys are of the widmanstätten structure with typical basket weave features, and the prior ß grain size and α lamellar spacing are refined with the increase of Y content. The precipitates in the alloys mainly include Y2O3 and (TiZr)6Si3 silicide phases. The Y2O3 phase has specific orientation relationships with the α-Ti phase: (002)Y2O3 // (1¯1¯20)α-Ti, [110]Y2O3 // [4¯401]α-Ti. (TiZr)6Si3 has an orientation relationship with the ß-Ti phase: (022¯1¯)(TiZr)6Si3 // (011)ß-Ti, [1¯21¯6](TiZr)6Si3 // [044¯]ß-Ti. The 0.1 wt.% Y composition alloy has the best high-temperature oxidation resistance at different temperatures. The oxidation behaviors of the alloys follow the linear-parabolic law, and the oxidation products of the alloys are composed of rutile-TiO2, anatase-TiO2, Y2O3 and Al2O3. The room-temperature and 700 °C UTS of the alloys decreases first and then increases with the increase of Y content; the 0.1 wt.% Y composition alloy has the best room-temperature mechanical properties with a UTS of 1012 MPa and elongation of 1.0%. The 700 °C UTS and elongation of the alloy with 0.1 wt.% Y is 694 MPa and 9.8%, showing an optimal comprehensive performance. The UTS and elongation of the alloys at 750 °C increase first and then decrease with the increase of Y content. The optimal UTS and elongation of the alloy is 556 MPa and 10.1% obtained in 0.2 wt.% Y composition alloy. The cleavage and dimples fractures are the primary fracture mode for the room- and high-temperature tensile fracture, respectively.

Trends in care quality in China from 2011 to 2017: An analysis based on the National Specific (Single) Disease Monitoring System.

Background: The Ministry of Health of China conducted a study targeting in single-disease quality control in 2009, aimed to strengthen quality management and improve health care services. This study retrospectively investigated the trends of quality indicators for six monitored diseases 2011-2017 to evaluate the improvement of care quality for the first batch of single-disease. Methods: We extracted data from the National Specific (Single) Disease Monitoring System for 2011-2017. We focused on six conditions: acute myocardial infarction, heart failure, community-acquired pneumonia, coronary artery bypass graft, hip / knee replacement, and acute ischemic stroke. A total of 56 quality indicators (QIs) were adopted to monitor the quality change and determine the trends in care quality. We also calculated the hospital process composite performance (HPCP) using a denominator-based weighting method for each hospital per year. The estimated annual percentage changes (EAPC) 2011-2017 were calculated at national and regional levels. Results: The results showed that use of four QIs had significant downward trends, whereas 25 QIs (including reversed indicators) showed significant upward trends from 2011 to 2017. The greatest improvement was observed in CAP-4 (antibiotic treatment within four hours after admission to the hospital for critical pneumonia) in the central region (EAPC = 48.36, 95% CI = 15.92-89.87); while the largest decrease appeared in AIS-1 (thrombolytic therapy within 4.5 hours of symptom onset) in the western region (EAPC = -13.44, 95% CI = -24.98,-0.11). An increased HPCP was observed in four diseases nationwide, but not for acute myocardial infarction and heart failure. However, there were significant differences across regions in the process of care and outcomes, with the performance of Eastern and Western regions showing remarkable advantages compared with the Central region. Conclusions: We provide evidence for major advancement in care quality in China nationwide. However, the improvement of care in China was unbalanced geographically and should be carefully considered. Future challenges include expanding the coverage of quality monitoring, greater delivery efficiency, and region-balanced health care.

Surface-enhanced Raman scattering based determination on sulfamethazine using molecularly imprinted polymers decorated with silver nanoparticles.

Molecularly imprinted polymers (MIPs) were combined with surface-enhanced Raman scattering (SERS) and AgNPs were prepared by in situ reduction within the MIP for selective and sensitive detection of sulfamethazine (SMZ). The MIP@AgNPs composites were characterized in detail by several analytical techniques, showing the generation of polymers and the formation of AgNPs hot spots. The specific affinity and rapid adsorption equilibrium rates of MIP@AgNPs composites were verified by static and kinetic adsorption studies. The MIP@AgNPs with high selectivity and excellent sensitivity were used as SERS substrates to detect SMZ. A good linear correlation (R2 = 0.996) in rang of 10-10-10-6 mol L-1 was observed between the Raman signal (1596 cm-1) and the concentration of SMZ. The limit of detection (LOD) was as low as 8.10 × 10-11 mol L-1 with relative standard deviations (RSD) of 6.32%. The good stability and reproducibility are also fully reflected in the SERS detection based on MIP@AgNPs. The method was successfully applied to the analysis of lake water samples, with recoveries in the range 85.1% to 102.5%. In summary, SERS detection based on MIP@AgNPs can be developed for a wider and broader range of practical applications. Schematic illustration of MIP@AgNPs sensor for the SERS detection of sulfamethazine.

Associations between the compositional patterns of blood volatile organic compounds and chronic respiratory diseases and ages at onset in NHANES 2003-2012.

BACKGROUND: and Purpose Volatile organic compounds (VOCs) pose a serious respiratory hazard. This study evaluated the relationship between the compositional patterns of blood VOCs and the risk and age at onset of chronic respiratory diseases (CRDs), including asthma, emphysema and chronic bronchitis, with the objective of preventing or delaying CRDs. METHODS: Participants from five cycles of the NHANES survey were included. Blood VOCs were clustered using k-means clustering. Differences in VOCs and age at onset between multiple groups were compared with the Kruskal‒Wallis test. Logistic regression and a generalized linear model were applied to examine the associations between different compositional patterns of blood VOCs and risk and age at onset of CRDs. RESULTS: 12,386 participants were enrolled in this study. Three VOC compositional patterns were identified after clustering nine species of blood VOCs. The concentration of VOCs in pattern 2 was relatively low and stable. The concentrations of benzene, ethylbenzene, o-xylene, styrene, toluene and m-p-xylene in pattern 3 and the concentrations of 1,4-dichlorobenzene and MTBE in pattern 1 were significantly higher than those in pattern 2. After adjustment for covariates, the participants with VOC pattern 3 had an increased risk of asthma (OR = 1.23, 95% CI: 1.02, 1.49), emphysema (OR = 3.37, 95% CI: 2.24, 5.06) and chronic bronchitis (OR = 1.79, 95% CI: 1.30, 2.45). Meanwhile, VOC pattern 3 was negatively correlated with the age at onset of asthma (ß = -5.61, 95% CI: 9.69, -1.52) and chronic bronchitis (ß = -9.17, 95% CI: 13.96, -4.39). VOC pattern 1 was not associated with either risk or age at onset of the three CRDs after adjustment. CONCLUSIONS: Changing the compositional pattern of blood VOCs by reducing certain species of VOCs may be a new strategy to lengthen the ages at onset of CRDs and effectively prevent them.

The Antibacterial Effect, Biocompatibility, and Osteogenesis of Vancomycin-Nanodiamond Composite Scaffold for Infected Bone Defects.

Purpose: The repair and treatment of infected bone defects (IBD) is a common challenge faced by orthopedic clinics, medical materials science, and tissue engineering. Methods: Based on the treatment requirements of IBD, we utilized multidisciplinary knowledge from clinical medicine, medical materials science, and tissue engineering to construct a high-efficiency vancomycin sustained-release system with nanodiamond (ND) and prepare a composite scaffold. Its effect on IBD treatment was assessed from materials, cytology, bacteriology, and zoology perspectives. Results: The results demonstrated that the Van-ND-45S5 scaffold exhibited an excellent antibacterial effect, biocompatibility, and osteogenesis in vitro. Moreover, an efficient animal model of IBD was established, and a Van-ND-45S5 scaffold was implanted into the IBD. Radiographic and histological analyses and bone repair-related protein expression, confirmed that the Van-ND-45S5 scaffold had good biocompatibility and osteogenic and anti-infective activities in vivo. Conclusion: Collectively, our findings support that the Van-ND-45S5 scaffold is a promising new material and approach for treating IBD with good antibacterial effects, biocompatibility, and osteogenesis.

Increasingly amplified stimulation mediated by TaNAC69-B is crucial for the leaf senescence in wheat.

Leaf senescence involves massive multidimensional alterations, such as nutrient redistribution, and is closely related to crop yield and quality. No apical meristem, Arabidopsis transcription activation factor, and Cup-shaped cotyledon (NAC)-type transcription factors integrate various signals and modulate an enormous number of target genes to ensure the appropriate progression of leaf senescence. However, few leaf senescence-related NACs have been functionally characterized in wheat. Based on our previous RNA-sequencing (RNA-seq) data, we focused on a NAC family member, TaNAC69-B, which is increasingly expressed during leaf senescence in wheat. Overexpression of TaNAC69-B led to precocious leaf senescence in wheat and Arabidopsis, and affected several agricultural traits in transgenic wheat. Moreover, impaired expression of TaNAC69-B by virus-induced gene silencing retarded the leaf senescence in wheat. By RNA-seq and quantitative real-time polymerase chain reaction analysis, we confirmed that some abscisic acid (ABA) biosynthesis genes, including AAO3 and its ortholog in wheat, TraesCS2B02G270600 (TaAO3-B), were elevated by the overexpression of TaNAC69-B. Consistently, we observed more severe ABA-induced leaf senescence in TaNAC69-B-OE wheat and Arabidopsis plants. Furthermore, we determined that TaNAC69-B bound to the NAC binding site core (CGT) on the promoter regions of AAO3 and TaAO3-B. Moreover, we confirmed elevated ABA levels in TaNAC69-B-OE wheat lines. Although TaNAC69-B shares 39.83% identity (amino acid) with AtNAP, TaNAC69-B did not completely restore the delayed leaf senescence in the atnap mutant. Collectively, our results revealed a positive feedback loop, consisting of TaNAC69-B, ABA biosynthesis and leaf senescence, that is essential for the regulation of leaf senescence in wheat.

Doped Graphene To Mimic the Bacterial NADH Oxidase for One-Step NAD+ Supplementation in Mammals.

Nicotinamide adenine dinucleotide (NAD) is a critical regulator of metabolic networks, and declining levels of its oxidized form, NAD+, are closely associated with numerous diseases. While supplementing cells with precursors needed for NAD+ synthesis has shown poor efficacy in combatting NAD+ decline, an alternative strategy is the development of synthetic materials that catalyze the oxidation of NADH into NAD+, thereby taking over the natural role of the NADH oxidase (NOX) present in bacteria. Herein, we discovered that metal-nitrogen-doped graphene (MNGR) materials can catalyze the oxidation of NADH into NAD+. Among MNGR materials with different transition metals, Fe-, Co-, and Cu-NGR displayed strong catalytic activity combined with >80% conversion of NADH into NAD+, similar specificity to NOX for abstracting hydrogen from the pyridine ring of nicotinamide, and higher selectivity than 51 other nanomaterials. The NOX-like activity of FeNGR functioned well in diverse cell lines. As a proof of concept of the in vivo application, we showed that FeNGR could specifically target the liver and remedy the metabolic flux anomaly in obesity mice with NAD+-deficient cells. Overall, our study provides a distinct insight for exploration of drug candidates by design of synthetic materials to mimic the functions of unique enzymes (e.g., NOX) in bacteria.

Routine analysis of pesticides in foodstuffs: Emerging ambient ionization mass spectrometry as an alternative strategy to be on your radar.

Pesticides residues in foodstuffs are longstanding of great concern to consumers and governments, thus reliable evaluation techniques for these residues are necessary to ensure food safety. Emerging ambient ionization mass spectrometry (AIMS), a transformative technology in the field of analytical chemistry, is becoming a promising and solid evaluation technology due to its advantages of direct, real-time and in-situ ionization on samples without complex pretreatments. To provide useful guidance on the evaluation techniques in the field of food safety, we offered a comprehensive review on the AIMS technology and introduced their novel applications for the analysis of residual pesticides in foodstuffs under different testing scenarios (i.e., quantitative, screening, imaging, high-throughput detection and rapid on-site analysis). Meanwhile, the creative combination of AIMS with high-resolution mass analyzer (e.g., orbitrap and time-of-flight) was fundamentally mentioned based on recent studies about the detection and evaluation of multi-residual pesticides between 2015 and 2021. Finally, the technical challenges and prospects associated with AIMS operation in food industry were discussed.

The quality disparity of stroke care over time: An analysis based on the national dataset from 2011 to 2017.

BACKGROUND: Adherence to evidence-based hospital stroke care is variable and may change over time. It is important to determine which process measures are associated with variation in outcome. In a large dataset, we analyzed the association between process and outcome and the fluctuations of indicators over time, and identified quality indicators (QIs) that should be prioritized for improving the quality of stroke care. METHODS: We analyzed data from 123,259 patients diagnosed with acute ischemic stroke (AIS) who were treated at 109 large tertiary hospitals in China between January 2011 and May 2017. In total, 12 stroke treatment indicators were selected to calculate the hospital process composite performance (HPCP). Hospitals were divided into subgroups according to the time trend of HPCP estimated by the Group-Based Model. We analyzed the influence of hospital subgroups on the patient outcomes using a multi-level model and explored the QIs that led to variation. RESULTS: The HPCP trends for stroke indicators of 109 hospitals over 7 years were divided into two groups (Group 1, low-HPCP; Group 2, high-HPCP). After adjusting for patient age, medical insurance, comorbidities, patterns of admission, and NIHSS-scores, patients in the high-HPCP group presented higher rate of independence and longer length of stay compared to the low-HPCP group. The multi-level model showed that there was a statistically significant difference in the utilization rate between the two groups, with most marked differences seen in emergency assessment and function evaluation indicators. CONCLUSION: Variation in the quality of stroke care exists across hospitals, and better adherence to guideline-based care is associated with improved outcomes. We found that QIs related to emergency examination and functional assessment were the main factors differing between good and poor adherers to stroke indicators, suggesting that quality improvement in stroke care could prioritize these QIs.

Effect of Cold-Rolling Reduction on Recrystallization Microstructure, Texture and Corrosion Properties of the X2CrNi12 Ferritic Stainless Steel.

X2CrNi12 ferritic stainless steel has a wide range of application prospects in the railway transportation, construction, and automobile fields due to its excellent properties. The properties of X2CrNi12 ferritic stainless steel can be further improved by cold-rolling and subsequent annealing treatment. The purpose of this work is to investigate the effect of cold-rolling reduction on the microstructure, texture and corrosion properties of the recrystallized X2CrNi12 ferritic stainless steel by using SEM, TEM, EBSD and electrochemical testing technology. The results show that the crystal orientation characteristics of the cold-rolled sheet could be inherited into the annealed sheet. The higher cold-rolling reduction could promote the deformed grains rotating into the {111} orientation, increasing storage energy and driving force for recrystallization, which could reduce the recrystallized grain size. The orientation densities of α-fiber and γ-fiber were low at 50% cold-rolling reduction. After recrystallization annealing, a large number of grains with random orientation could be produced, and the texture strength was weakened. When the cold-rolling reduction rose to 90%, the γ-fiber texture at {111}<110> was strengthened and the α-fibers, particularly the {112}<110> component, were weakened after recrystallisation annealing, which could improve the formability of the steels. The proportions of special boundaries, i.e., low-angle grain boundaries and low-Σ CSL boundaries, among the grain boundary distribution of the recrystallized X2CrNi12 stainless steel were higher when the reduction was 90%, especially when the annealing temperature was 770 °C. Additionally, the proportion of LAGBs and low-Σ CSL boundaries were 53% and 7.43%, respectively, which improves the corrosion resistance of the matrix, showing the best corrosion resistance.

Covalent organic nanospheres as a fiber coating for solid-phase microextraction of genotoxic impurities followed by analysis using GC-MS.

Covalent organic nanospheres (CONs) were explored as a fiber coating for solid-phase microextraction of genotoxic impurities (GTIs) from active ingredients (AIs). CONs were synthesized by an easy solution-phase procedure at 25 °C. The obtained nanospheres exhibited a high specific surface area, good thermostability, high acid and alkali resistance, and favorable crystallinity and porosity. Two types of GTIs, alkyl halides (1-iodooctane, 1-chlorobenzene, 1-bromododecane, 1,2-dichlorobenzene, 1-bromooctane, 1-chlorohexane, and 1,8-dibromooctane) and sulfonate esters (methyl p-toluenesulfonate and ethyl p-toluenesulfonate), were chosen as target molecules for assessing the performance of the coating. The prepared coating achieved high enhancement factors (5097-9799) for the selected GTIs. The strong affinity between CONs and GTIs was tentatively attributed to π-π and hydrophobicity interactions, large surface area of the CONs, and size-matching of the materials. Combined with gas chromatography-mass spectrometry (GC-MS), the established analytical method detected the GTIs in capecitabine and imatinib mesylate samples over a wide linear range (0.2-200 ng/g) with a low detection limit (0.04-2.0 ng/g), satisfactory recovery (80.03%-109.5%), and high repeatability (6.20%-14.8%) and reproducibility (6.20%-14.1%). Therefore, the CON-coated fibers are promising alternatives for the sensitive detection of GTIs in AI samples.

SNHG20 promotes the development of laryngeal squamous cell carcinoma via miR-342-3p/MTDH axis.

Long noncoding RNAs (lncRNAs) are important players in laryngeal squamous cell carcinoma (LSCC). However, the function of the long noncoding RNA small nucleolar RNA host gene 20 (SNHG20) in LSCC is hardly known. We therefore analyzed the role of this lncRNA in LSCC. Our data showed that SNHG20 was significantly overexpressed in LSCC cell lines and human LSCC tissue. SNHG20 significantly promoted cell proliferation, migration and invasion of LSCC cells. The actions of SNHG20 are likely mediated by miR-342-3p expression, which results in increased expression of MTDH. Finally, the results of in vivo models confirmed that SNHG20 promotes LSCC progression through modulating miR-342-3p and MTDH expression. Taken together, our study demonstrates that SNHG20/miR-342-3p/MTDH axis participates in LSCC progression.

Highly sensitive sensing and quantitative detection of sulfate ion with a SERS chip-based on boric acid's Lewis effect.

Based on the Lewis acid's coordination principle, a surface-enhanced Raman scattering (SERS) chip strategy had been developed for the ultrasensitive quantitation of SO42-. Through the immobilization of silver nanoparticles (Ag NPs) and the construction of the boric acid-based sensing unit, the chip system displayed outstanding merits on the direct sensing of SO42-, e.g., simple operation, ultra-high sensitivity, reproducibility, excellent selectivity and specificity. Moreover, an accurate evaluation was obtained by ratiometric calculations on characteristic peaks (1382 and 1070 cm-1) for quantitative detection of SO42-. The detection limit was down to 10 nM. Tap water, beer, and mineral water samples were tested, and high recoveries were achieved (97.12-110.12%). Besides, such SERS chip also displayed strong applicability for the evaluation of SO32-. Therefore, this SERS chip provided a promising idea for the quantification of trace amounts of SO42- and SO32- in the fields of food safety and environmental monitoring.

Recent advances of three-dimensional micro-environmental constructions on cell-based biosensors and perspectives in food safety.

The development and application of cell-based biosensors (CBBs) provides a convenient strategy for rapid detection of target analytes. The CBBs had been widely applied in the fields of food safety, environment monitoring, and medicine diagnosis due to their advantages of short response time, easy operation, low toxicity, and portability. However, the CBBs based on two-dimensional (2D) cultured cells in-vitro suffer from a lower cell viability and isolated physiology, which had blocked the accurate evaluations of these biosensors. With the development of nanotechnology and three-dimensional (3D) printing technology, cells fixed in a 3D biosensor or a 3D microenvironment have shown great improvement in the sensitivity and detection authenticity than conventional CBBs. To promote the further development of CBBs, in this paper, we reviewed the related technologies used to construct 3D bionic cell chips including organic/inorganic agents and operating approaches suitable for constructing 3D cell cultural microenvironment. Then, the applications of 3D bionic cell chip based on microbial and mammalian cell biosensors in food safety field were discussed during recent ten years. Finally, the current challenges and further directions were summarized and prospected.

Effect of Cu Content on the Precipitation Behaviors, Mechanical and Corrosion Properties of As-Cast Ti-Cu Alloys.

Ti-Cu alloys have broad application prospects in the biomedical field due to their excellent properties. The properties of Ti-Cu alloys are strongly dependent on Cu content, microstructures, its Ti2Cu phase and its preparation process. The aim of this work is to investigate the effect of Cu content on the precipitation behaviors, mechanical and corrosion properties of the as-cast Ti-Cu alloys. The microstructures and phase evolution were characterized by SEM and TEM, and the properties were studied by tensile and electrochemical test. The results show that the volume fraction of Ti2Cu phase increases with the increase of Cu content. The Ti2Cu phase presents a variety of microscopic morphologies with different Cu content, such as rod, granular, lath and block shaped. The crystal orientation relationships between the Ti2Cu and α-Ti matrix in Ti-4Cu and Ti-10Cu alloys are (103)Ti2Cu//(0[11¯11)α-Ti, [3¯01]Ti2Cu//[21¯1¯0]α-Ti, and (103)Ti2Cu//(0002)α-Ti, [3¯31]Ti2Cu//[12¯10]α-Ti, respectively. The tensile strength, Vickers hardness and Young's modulus of the Ti-Cu alloys increase with the increase of Cu content, whereas the elongation decreases. The fracture morphologies of these alloys reveal ductile, ductile-brittle hybrid, and cleavage brittle mode, respectively. The corrosion resistance of the Ti-Cu alloys in SBF solution can be described as: Ti-4Cu alloy > Ti-10Cu alloy > Ti-7Cu alloy. The volume fraction of Ti2Cu phases and the "protective barrier" provided by the fine lath Ti2Cu phases strongly affected the electrochemical performances of the alloys.