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In this work, we demonstrated a novel approach of corrosion protection based on the fabrication of polyelectrolyte/SiO2 nanoparticles multilayers on magnesium alloys. The original multilayers based merely on electrostatic attraction showed porous morphology and weak anti-corrosion protection for the Mg substrate. However, the heat-treatment process would change the microstructures of the multilayers through the cross-linking between the polyelectrolytes and the capping agents of the nanoparticles, and the barrier effects of the coating could be confirmed by polarization and electrochemical impedance spectroscopy. Thus the heat treatment would be an applicable option for preparing the layer-by-layer assembled anti-corrosive multilayers on biomedical Mg alloys.

Background Postoperative delirium (POD), one of the most common complications following major surgery, imposes a heavy burden on patients and society. The objective of this exploratory study was to conduct a secondary analysis to identify whether there exist novel and reliable serum biomarkers for the prediction of POD. Methods A total of 131 adult patients (≥ 65 years) undergoing lower extremity orthopedic surgery with were enrolled in this study. Cognitive function was assessed preoperatively with Mini-Mental State Examination (MMSE). Delirium was diagnosed according to the Confusion Assessment Method (CAM) criteria on preoperative day and postoperative days 1–3. The preoperative serum levels of a panel of 16 biochemical parameters were measured by ELISA. Results Thirty-five patients developed POD, with an incidence of 26.7%. Patients in POD group were older (P = 0.001) and had lower preoperative MMSE scores (P = 0.001). Preoperative serum levels of prostaglandin E2 (PGE2, P P P P = 0.002) in POD group were significantly increased. Logistic regression analysis showed that advanced age (OR = 1.144, 95%CI: 1.008 ~ 1.298, P = 0.037), higher serum neurofilament light (OR = 1.003, 95%CI: 1.000 ~ 1.005, P = 0.036) and PGE2 (OR = 1.031, 95%CI: 1.018 ~ 1.044, P P Conclusions Our study showed that higher preoperative serum PGE2 level might be a biomarker to predict the occurrence of POD in elderly patients undergoing elective orthopedic surgery. Trial registration NCT03792373 www.clinicaltrials.gov.

A hydrothermal deposition method was utilized to fabricate Ca-P composite coating induced by the layer-by-layer (LbL) assembled polyvinylpyrrolidone/deoxyribonucleic acid (PVP/DNA)20 multilayer on AZ31 alloy. The surface morphology and compositions were characterized by SEM, EDS, FTIR and XRD. Besides, the corrosion resistance and degradation behavior of the coating were tested via electrochemical polarization, impedance spectroscopy and immersion measurements. Results show that the main components of Ca-P coatings are hydroxyapatite, Ca3(PO4)2 and Mg3(PO4)2·nH2O. The LbL-assembled DNA and PVP promote the adsorption of Ca-P deposits on the sample surface, and structures and functional groups of the polyelectrolyte in the outermost layer are the primary influencing factor for the induction of the Ca-P coating. Carboxyl groups have the best biomineralization effect among all related functional groups. The enhanced corrosion resistance and adhesion highlight a promising use of (PVP/DNA)20-induced Ca-P coatings in the field of biomedical magnesium alloys.

Magnesium (Mg) and its alloys are considered as ideal biodegradable materials due to their excellent mechanical properties and biocompatibility. In order to improve the surface properties to allow better adaptation to the surrounding tissue of the body, surface modification has played a significant role in satisfying multiple clinical requirements such as corrosion resistance, biocompatibility, and antibacterial ability. Here, layer-by-layer (LbL) self-assembly, which can be applied for biodegradable Mg alloys due to its extensive choice of usable units, holds great promise among all the surface techniques. In this review, the mechanisms of the driving force (i.e., electrostatic interaction, hydrogen bonding, charge transfer interaction and covalent bonding), cutting-edge advances in preparation methods (e.g., dipping, spraying, and spinning) and the functional properties (corrosion resistance, antibacterial activity, and biocompatibility) that could be achieved by the LbL coatings are summarized. A reasonable trend of the potential development of LbL for bio-Mg alloys is also proposed at the end of this article.

Magnesium (Mg) alloys as a bioabsorbable light metal have shown great clinical potential as bone replacement implants. In this review, the categories, progress in cutting-edge preparation technologies and antibacterial mechanisms of Mg alloys and considerable numbers of corrosion-resistant and functional coatings are summarized. The relationship among the microstructure (grain size, intermetallic compounds), biocorrosion resistance and biocompatibility for antibacterial Mg alloys is discussed. The challenge and outlooks of biomedical Mg alloys and coatings are proposed from an antibacterial perspective.

In this paper, we report a top-gate amorphous In–Al–Zn–O (a-IAZO) thin film transistor (TFT) based on dip-coated poly(methyl methacrylate) (PMMA) dielectric layer and investigate PMMA thickness influence on a-IAZO TFT performance. A thinner PMMA gate dielectric can cumulate more charges per unit area and induce more electron carriers, resulting in increasing of on-state current of TFT. Moreover, it is found that a TFT with the thinner PMMA gate dielectric contains less trap states at a-IAZO/PMMA interface due to decreased surface roughness with thinner PMMA dielectric, which is essential for reducing the capture of electron carriers in the process of electron transport. Therefore, the on/off current ratio (Ion/off), saturated mobility (μsat) and subthreshold gate swing (SS) of device improved with the PMMA thickness decreased from 610 to 280 nm. Furthermore, experimental results show that the PMMA thickness plays an important role on controlling the threshold voltage (Vth) and adjusting the operating mode of device, thus influencing on the power dissipation. Overall, the TFT with a 390-nm-thick PMMA dielectric layer exhibits the adequate operating mode (enhancement mode) and the high electrical performance (a high μsat of 21.42 cm2/Vs, a small SS of 0.46 V/decade, a close-to-zero Vth of 0.12 V, and Ion/off of more than104).

Epiretinal prostheses aim at electrically stimulating the inner most surviving retinal cells—retinal ganglion cells (RGCs)—to restore partial sight to the blind. Recent tests in patients with epiretinal implants have revealed that electrical stimulation of the retina results in the percept of color of the elicited phosphenes, which depends on the frequency of stimulation. This paper presents computational results that are predictive of this finding and further support our understanding of the mechanisms of color encoding in electrical stimulation of retina, which could prove pivotal for the design of advanced retinal prosthetics that elicit both percept and color. This provides, for the first time, a directly applicable “amplitude-frequency” stimulation strategy to “encode color” in future retinal prosthetics through a predictive computational tool to selectively target small bistratified cells, which have been shown to contribute to “blue-yellow” color opponency in the retinal circuitry. The presented results are validated with experimental data reported in the literature and correlated with findings in blind patients with a retinal prosthetic implant collected by our group.

Brain dysfunction is a common complication after sepsis and is an independent risk factor for a poor prognosis, which is partly attributed to the dysregulated inflammatory response and oxidative damage. Melatonin regulates the sleep-wake cycle and also has potent anti-inflammatory and antioxidant properties, yet the protective effects of melatonin on sepsis-induced neurobehavioral dysfunction remain to be elucidated. In the present study, melatonin was administered intraperitoneally daily at a dose of 10 mg/kg for three consecutive days immediately (early treatment) or 7 days (delayed treatment) after sham operation or cecal ligation and puncture (CLP), followed by an additional treatment in drinking water until the end of behavioral tests. The concentrations of pro-inflammatory cytokines (tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), IL-6, IL-10), malondialdehyde (MDA), superoxide dismutase (SOD), reactive oxygen species (ROS), brain-derived neurotrophic factor (BDNF), and glial cell line-derived neurotrophic factor (GDNF) were determined at the indicated time points. Compared with the CLP + vehicle group, we found that early melatonin treatment resulted in increased survival rate but not improvement in measures of neurobehavioral outcomes, which was accompanied by significantly lower plasma level of IL-1β. Intriguingly, delayed melatonin treatment improved neurobehavioral dysfunction by normalization of hippocampal BDNF and GDNF expressions. In conclusion, our study suggests the beneficial effects of both early and delayed melatonin treatment after sepsis development, which implicates melatonin has a potential therapeutic value in sepsis-associated organ damage including brain dysfunction.

Influence of glucose on corrosion of biomedical Mg-1.35Ca alloy was made using hydrogen evolution, pH and electrochemical polarization in isotonic saline solution. The corrosion morphologies, compositions and structures were probed by virtue of SEM, EDS, FTIR, XRD and XPS. Results indicate that the glucose accelerated the corrosion of the alloy. The elemental Ca has no visible effect on the corrosion mechanism of glucose for the Mg-1.35Ca alloy in comparison with pure Mg. In addition, the presence of CO2 has beneficial effect against corrosion due to the formation of a layer of carbonatecontaining products.

Mg-Li based alloys hold much attention as potential biomedical materials due to their excellent ductility. A reduced mechanical strength and concern for biocompatibility are exhibited for Mg-Li binary alloys due to the presence of Li element. Addition of the Ca element into Mg-Li alloys leads to an improvement in mechanical strength and biocompatibility. In the present work, the microstructure, mechanical property and corrosion behaviors of three kinds ( α , α + β , β ) of as-extruded Mg-Li (1, 9 and 15 wt.%)-1Ca alloys were investigated using optical microscope, X-ray diffraction (XRD), tensile, immersion and electrochemical polarization measurements. In vitro biocompatibility was evaluated by cytotoxicity assays, hemolysis and four coagluation tests. The results indicated that the Mg-1Li-1Ca and Mg-15Li-1Ca alloys were characterized by α -Mg and β -Li phases besides Mg2Ca particles, respectively; while the Mg-9Li-1Ca by dual ( α -Mg+ β -Li) phase together with Mg2Ca phase. The Mg-1Li-1Ca alloy had the highest ultimate tensile strength (UTS) and yield strength (YS) and the lowest elongation (EL) to failure (10.1±1.24%) as well. The EL for the Mg-9Li-1Ca alloy was the highest (52.2±0.01%). The long-term immersion tests revealed a decrease in corrosion resistance with increasing Li content. The results of cytotoxicity assays clearly showed that the Mg-Li-Ca alloys demonstrated no toxicity to L-929 cells in 10% concentration of extracts. The Mg-1Li-1Ca alloy also exhibited an acceptable hemolysis ratio. The results of four coagulation tests designated no sign of thrombogenicity for the Mg-Li-Ca alloys except for the Mg-15Li-1Ca alloy.

A polymethyltrimethoxysilane (PMTMS)/hydroxyapatite (HA) hybrid coating was successfully fabricated on a magnesium alloy by hydrothermal treatment and immersion method. The microstructure and composition of the coating were characterized by using X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. The physical properties were investigated using scratch testing. At the same time, the corrosion resistance was evaluated via electrochemical and immersion tests. The results demonstrated that the corrosion resistance of the silane hybrid coating was significantly enhanced compared with the naked magnesium alloy. Especially, the corrosion current density of the PMTMS/HA magnesium alloy was three orders of magnitude lower than that of the bare material.

A superhydrophobic surface was successfully constructed to modify the layered double hydroxide (LDH) coatings on aluminum alloy using stearic acid. The characteristics of the coatings were investigated using SEM, XRD, FT-IR and XPS. The corrosion resistance of the prepared coatings was studied using potentiodynamic polarization and electrochemical impedance spectrum. The results revealed that the superhydrophobic surface considerably improved the corrosion-resistant performance of the LDH coatings on the aluminum alloy substrate. The formation mechanism of the superhydrophobic surface was proposed.

Background During fresh fruit consumption, sensory texture is one factor that affects the organoleptic qualities. Chemical components of plant cell walls, including pectin, cellulose, hemicellulose and lignin, play central roles in determining the textural qualities. To explore the genes and regulatory pathways involved in fresh citrus’ perceived sensory texture, we performed mRNA-seq analyses of the segment membranes of two citrus cultivars, Shiranui and Kiyomi, with different organoleptic textures. Results Segment membranes were sampled at two developmental stages of citrus fruit, the beginning and end of the expansion period. More than 3000 differentially expressed genes were identified. The gene ontology analysis revealed that more categories were significantly enriched in ‘Shiranui’ than in ‘Kiyomi’ at both developmental stages. In total, 108 significantly enriched pathways were obtained, with most belonging to metabolism. A detailed transcriptomic analysis revealed potential critical genes involved in the metabolism of cell wall structures, for example, GAUT4 in pectin synthesis, CESA1, 3 and 6, and SUS4 in cellulose synthesis, CSLC5, XXT1 and XXT2 in hemicellulose synthesis, and CSE in lignin synthesis. Low levels, or no expression, of genes involved in cellulose and hemicellulose, such as CESA4, CESA7, CESA8, IRX9 and IRX14, confirmed that secondary cell walls were negligible or absent in citrus segment membranes. A chemical component analysis of the segment membranes from mature fruit revealed that the pectin, cellulose and lignin contents, and the segment membrane’s weight (% of segment) were greater in ‘Kiyomi’. Conclusion Organoleptic quality of citrus is easily overlooked. It is mainly determined by sensory texture perceived in citrus segment membrane properties. We performed mRNA-seq analyses of citrus segment membranes to explore the genes and regulatory pathways involved in fresh citrus’ perceived sensory texture. Transcriptomic data showed high repeatability between two independent biological replicates. The expression levels of genes involved in cell wall structure metabolism, including pectin, cellulose, hemicellulose and lignin, were investigated. Meanwhile, chemical component contents of the segment membranes from mature fruit were analyzed. This study provided detailed transcriptional regulatory profiles of different organoleptic citrus qualities and integrated insights into the mechanisms affecting citrus’ sensory texture. Electronic supplementary material The online version of this article (10.1186/s12864-018-4669-y) contains supplementary material, which is available to authorized users.

The temporal and spatial features of annual average groundwater recharge play an important role in managing groundwater resources. The digital filter technique is employed to separate baseflow from streamflow, and then the recession curve displacement method is applied to estimate the annual average monthly groundwater recharge. The streamflow data of 15 gauging stations are applied to investigate the temporal and spatial features of annual monthly average groundwater recharge in Grand River watershed, Michigan, US. The results show that (1) the annual monthly average groundwater recharge in Grand River watershed gradually drops from 40.82 cm/a in March to 10.50 cm/a in August. In period of September and February of the next year, the annual monthly average groundwater recharge steadily rises to 40.82 cm. The temperatures are the main reason that caused the significantly change of annual monthly average groundwater recharge. (2) The temporal feature of annual seasonal average groundwater recharge obey that “the annual seasonal average groundwater recharge in spring is the highest and that in summer is the lowest; the annual seasonal average groundwater recharge in winter and autumn are between that in spring and summer”. (3) In spring, summer, and autumn, the annual seasonal average groundwater recharge in upper reaches is less than that in lower reaches. While the annual seasonal average groundwater recharge in north Grand River watershed is higher than that in south, in winter. The characteristics of space distribution of annual seasonal average groundwater recharge are determined by atmospheric wet deposition, temperature, soil types, and vegetation coverage, and so on.

Realgar is a type of mineral drug containing arsenic. The nervous system toxicity of realgar has received extensive attention. However, the underlying mechanisms of realgar-induced neurotoxicity have not been clearly elucidated. To explore the mechanisms that contribute to realgar-induced neurotoxicity, weanling rats were exposed to realgar (0, 0.3, 0.9, 2.7 g/kg) for 6 weeks, and cognitive ability was tested using the Morris water maze (MWM) test and object recognition task (ORT). The levels of arsenic in the blood and hippocampus were monitored. The ultrastructures of hippocampal neurons were observed. The levels of glutamate (Glu) and glutamine (Gln) in the hippocampus and hippocampal CA1 region; the activities of glutamine synthetase (GS) and phosphate-activated glutaminase (PAG); the mRNA and protein expression of glutamate transporter 1 (GLT-1), glutamate/aspartate transporter (GLAST), and N-methyl-D-aspartate (NMDA) receptors; and the level of intracellular Ca(2+) were also investigated. The results indicate that the rats developed deficiencies in cognitive ability after a 6-week exposure to realgar. The arsenic contained in realgar and the arsenic metabolites passed through the blood-brain barrier (BBB) and accumulated in the hippocampus, which resulted in the excessive accumulation of Glu in the extracellular space. The excessive accumulation of Glu in the extracellular space induced excitotoxicity, which was shown by enhanced GS and PAG activities, inhibition of GLT-1 mRNA and protein expression, alterations in NMDA receptor mRNA and protein expression, disturbance of intracellular Ca(2+) homeostasis, and ultrastructural changes in hippocampal neurons. In conclusion, the findings from our study indicate that exposure to realgar induces excitotoxicity and that the mechanism by which this occurs may be associated with disturbances in Glu metabolism and transportation and alterations in NMDA receptor expression.

The high resolution of DOA(direction of arrival) estimation could be obtained by using the min-norm algorithm. In this paper, the expression of the min-norm spatial spectrum based on acoustic vector-sensor(AVS) linear arrays was presented and simulation study was carried out. Results of simulations indicated that left/right ambiguity could be removed and better performance for DOA estimation was obtainable when dealing with sources close to endfire than using pressure hydrophone linear arrays, and the interelement spacing was allowed to exceed the half-wavelength upper limit. A three-element vector hydrophone linear array with two meters interspace was designed. The AVS experiment was carried out at Songhua Lake in Jinlin Province. Experimental results show a high resolution tracking of targets can be obtained using the min-norm algorithm.

Photochemical switches represent a powerful method for improving pharmacological therapies and controlling cellular physiology. Here we report the photoregulation of GABA(A) receptors (GABA(A)Rs) by a derivative of propofol (2,6-diisopropylphenol), a GABA(A)R allosteric modulator, which we have modified to contain photoisomerizable azobenzene. Using α(1)β(2)γ(2) GABA(A)Rs expressed in Xenopus laevis oocytes and native GABA(A)Rs of isolated retinal ganglion cells, we show that the trans-azobenzene isomer of the new compound (trans-MPC088), generated by visible light (wavelengths ~440 nm), potentiates the γ-aminobutyric acid-elicited response and, at higher concentrations, directly activates the receptors. cis-MPC088, generated from trans-MPC088 by ultraviolet light (~365 nm), produces little, if any, receptor potentiation/activation. In cerebellar slices, MPC088 co-applied with γ-aminobutyric acid affords bidirectional photomodulation of Purkinje cell membrane current and spike-firing rate. The findings demonstrate photocontrol of GABA(A)Rs by an allosteric ligand, and open new avenues for fundamental and clinically oriented research on GABA(A)Rs, a major class of neurotransmitter receptors in the central nervous system.