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Monkeypox, caused by the monkeypox virus (MPXV), is a zoonotic disease endemic mainly in West and Central Africa. As of 27 September 2022, human monkeypox has occurred in more than 100 countries (mostly in non-endemic regions) and caused over 66,000 confirmed cases, which differs from previous epidemics that mainly affected African countries. Due to the increasing number of confirmed cases worldwide, the World Health Organization (WHO) has declared the monkeypox outbreak as a Public Health Emergency of International Concern on July 23, 2022. The international outbreak of human monkeypox represents a novel route of transmission for MPXV, with genital lesions as the primary infection, and the emergence of monkeypox in the current outbreak is also new, as novel variants emerge. Clinical physicians and scientists should be aware of this emerging situation, which presents a different scenario from previous outbreaks. In this review, we will discuss the molecular virology, evasion of antiviral immunity, epidemiology, evolution, and detection of MPXV, as well as prophylaxis and treatment strategies for monkeypox. This review also emphasizes the integration of relevant epidemiological data with genomic surveillance data to obtain real-time data, which could formulate prevention and control measures to curb this outbreak.

In this study, we uncovered the nuclear export of nucleus accumbens-associated protein-1 (NAC1) as a novel mechanism involved in ovarian cancer resistance to taxanes, the chemotherapeutic drugs commonly used in treatment of this malignancy. We showed that NAC1, a nuclear factor of the BTB/POZ gene family, has a nuclear export signal (NES) at the N terminus (aa 17-28), and this NES critically contributes to the NAC1 nuclear-cytoplasmic shuttling when tumor cells were treated with docetaxel. Mechanistically, the nuclear-exported NAC1 bound to cullin3 (Cul3) and cyclin B1 via its BTB and BOZ domains respectively, and the cyto-NAC1-Cul3 E3 ubiquitin ligase complex promotes the ubiquitination and degradation of cyclin B1, thereby facilitating mitotic exit and leading to cellular resistance to docetaxel. We also showed in in vitro and in vivo experiments that TP-CH-1178, a membrane-permeable polypeptide against the NAC1 NES motif, blocked the nuclear export of NAC1, interfered with the degradation of cyclin B1 and sensitized ovarian cancer cells to docetaxel. This study not only reveals a novel mechanism by which the NAC1 nuclear export is regulated and cyclin B1 degradation and mitotic exit are impacted by the NAC1-Cul3 complex, but also provides the nuclear-export pathway of NAC1 as a potential target for modulating taxanes resistance in ovarian cancer and other malignancies.

Background Excessive intraoperative hemorrhage is a critical factor of poor prognoses after hepatectomy. Low central venous pressure during parenchymal transection is recognized to effectively reduce intraoperative hemorrhage in open procedures. However, the role of controlled low central venous pressure in laparoscopic hepatectomy is still controversial. Methods In the present randomized clinical trial, we set up a standard boundary of low central venous pressure according to our Pilot Study, then enrolled patients scheduled for elective laparoscopic hepatectomy and allocated them randomly to a group undergoing central venous pressure reduction by anesthesiologic interventions or a control group. The primary efficacy endpoint was total intraoperative blood loss and perioperative adverse events. Analyses were performed following the intention-to-treat principle, and patients and surgeons were blinded ( ClinicalTrials.gov , Number: NCT03422913 ). Results Between January 2017 and October 2018, 146 out of 469 patients were randomized and eligible for inclusion in the final analyses. Based on the retrospective training cohort, we set a central venous pressure of 5 cm H2O as a cutoff value (standard low central venous pressure). Compared with patients in the control group, those in the controlled low central venous pressure group had a significantly lower central venous pressure during resection (4.83 ± 3.41 cm H2O vs 9.26 ± 3.38 cm H2O; P Conclusion The safety and efficacy of controlled low central venous pressure were demonstrated in complex laparoscopic hepatectomy for the first time by our study, and this technique is recommended to be applied routinely in laparoscopic hepatectomy.

Insights into the mechanism of hydrate nucleation are of great significance for the development of hydrate-based technologies, hydrate relevant flow assurance, and the exploration of in situ natural gas hydrates. Compared with the thermodynamics of hydrate formation, understanding the nucleation mechanism is challenging and has drawn substantial attention in recent decades. In this paper, we attempt to give a comprehensive review of the recent progress of studies of clathrate hydrate nucleation. First, the existing hypotheses on the hydrate nucleation mechanism are introduced and discussed. Then, we summarize recent experimental studies on induction time, a key parameter evaluating the velocity of the nucleation process. Subsequently, the memory effect is particularly discussed, followed by the suggestion of several promising research perspectives.

The catalytic performance of metal-acid bifunctional catalysts is strongly affected by metal-acid balance. However, the key parameter has not been systematically investigated for non-noble metal based hydroisomerization catalysts. Such a study was provided here for Ni/SAPO-11 catalyst prepared by in-situ solid synthesis method via varying nickel loading. Instead of channel properties, activity and selectivity of the catalyst were predominately governed by the metal-acid balance expressed by metal to acid sites ratio (CNi/CA). The activity per acid site (TOF) was shown to increase with CNi/CA until a plateau was reached, an observation that is in agreement with the classical bifunctional mechanism. Reaction scheme over catalysts with higher CNi/CA ratio was more approaching to the “ideal” consecutive one, and a higher selectivity to isomers was obtained. Result indicated that a single nickel site in the Ni/SAPO-11 catalyst was capable of feeding ca. 5 acid sites in n-hexane hydroisomerization. This work contributes to a deep insight into the metal-acid balance in nickel based hydroisomerization catalysts and can be extended to many other non-noble metal based bifunctional catalysts.

There are huge reserves of natural gas hydrates, a type of low-carbon energy resource, and it is considered important to study the stability conditions of hydrates in situ, to facilitate reserve evaluation and exploitation. The decomposition conditions of methane hydrate were determined in a quartz sand-brine mixing system, using an isothermal, stepwise, depressurising method. Influencing factors, such as sand particle size and pore water salt concentration, and the combined effect of these factors on the hydrate phase equilibrium, were investigated. The results showed that the decomposition pressure was distributed over a small range, and at specific temperatures. This may be partly related to the uneven distribution of pore size, but was shown to be mainly owing to the change of salt concentration during hydrate dissociation, as verified by differential scanning calorimetry. In addition, the hydrate dissociation pressure increased slightly with decreased particle size, and the maximum relative deviation of the dissociation pressure was 1.68%, when the sand particle size was within 100 mesh, which was mathematically negligible. For predicting the decomposition condition of hydrate in the quartz sand-brine mixing system, commercially-available CSMgem and PVTsim software showed high accuracy across a large temperature interval. An in-house, Chen-Guo hydrate model was valid when the temperature was below 277 K, while the Multiflash programme exhibited too large an error to be applied to this system.

A novel block copolymer is fabricated by orthogonally coupling two end-functionalized polymers, glucose-capped methoxypoly(ethylene glycol) (mPEG2k-diol) and phenylboronic acid-capped poly(e-caprolactone) (PBA-PCL), with dual boronate ester and B N/B O dynamic covalent interactions. Due to their synergetic effect, this block copolymer can self-assemble into micelles in aqueous solution with high stability. More importantly, micellar disassembly can be only triggered in the presence of both signal inputs, acid and salt, displaying an “AND” logic-gate responsive behavior.

Functionalization and bestowing high values upon bioactive tea polysaccharides have been focused recently. For this purpose, the immune activation effect on RAW264.7 macrophages promoted by Lu’an Guapian polysaccharide (LGP-1, 2.35 × 105 Da) was investigated firstly. LGP-1 was obtained and characterized via DEAE 52 ion exchange column, high performance liquid chromatography and atomic force microscope. Immunological assay manifested a remarkable promotion effect on macrophages. LGP-1 could significantly stimulate the phagocytosis of macrophages, promote NO generation and trigger TNF-α, IL-6, IL-1β release dose-dependently. Fluorescence labeling tests confirmed the production level of reactive oxygen species increased obviously. Western blot results demonstrated that the treated macrophages were able to increase PI3K expression and p65 nuclear translocation, indicated that LGP-1 enhanced macrophage immunity via PI3K/AKT and NF-κB signaling pathways. Moreover, TLR4 was involved in the process. These results made clear that LGP-1 could be explored as a bioactive substance applied in functional foods.

Herein, we report a two-photon ratiometric fluorescent pH nanosensor based on conjugated polymer poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) nanoparticles loaded with pH-sensitive fluorescein isothiocyanate (FITC) for intracellular pH monitoring. The obtained nanosensor (FITC-PFO NPs) possesses high sensitivity, excellent stability, good reversibility, favorable two-photon excitability and low cytotoxicity. The ratiometric fluorescence of FITC and PFO (F517/F417) in FITC-PFO NPs solution shows an efficient pH-sensitive response over the pH range from 3 to 10 (pKa = 6.43) under two-photon excitation. Additionally, the FITC-PFO NPs is successfully applied for ratiometric imaging of intracellular pH and its fluctuation in both one-photon and two-photon excitation modes. Overall, the two-photon pH nanosensor based on FITC-PFO NPs exhibits great potential in crucial physiological and biological processes related to intracellular pH fluctuations.

Although a lot of experimental research has been carried out to study the bond behaviour of the epoxy-coated reinforcement, corresponding predictive analytical models are quite limited. In order to solve this problem, first, an experimental investigation on bond behaviour of normal uncoated bars and epoxy-coated bars with two nominal coating thicknesses was carried out; following, a bond model for predicting the bond strength of epoxy-coated reinforcing bar was proposed by taking into account epoxy coating thickness, bar parameters, friction coefficient of the epoxy-coated bar and concrete, crushed concrete friction coefficient, cover-bar diameter ratio and the embedded length of the bar. The proposed bond model was verified by previously published tests and current one of the authors. Based on the model verification and discussion, taking into account the effect of bar size, embedded length and epoxy coating thickness, the proposed bond model suggests values of the effective rib face angle for the normal uncoated and epoxy coated bars, respectively.

Motion state of bottom hole assembly (BHA) has a great effect on the performance of downhole drilling tools. In this article, we developed a finite element model for characterizing the lateral motion of BHA in highly deviated wells taking discontinuous interaction between drill strings and wellbore into consideration. Numerical simulations were conducted by solving the motion equation through Newmark method. To verify the established model, an indoor experimental apparatus was built based on the similarity criterion. Numerical and experimental simulation results were compared and analyzed under different rotary speed, weight on bit (WOB) and well inclination condition. Both of the results showed that BHA locates in and swings along the lower right part of borehole in highly deviated wells without forming into backward whirl motion. Rotary speed has an obvious effect on BHA lateral motion state where the vibration amplitude and frequency get improved with the increase of rotary speed. Compared with rotary speed, WOB and well inclination angle has a much smaller effect on the BHA lateral motion in highly deviated wells. Based on the analyses, relevant recommendations were given for the engineering practical use. This study can help understand the dynamic characteristics of BHA in highly deviated wells and select operation parameters for better drilling.

Suffering weak mechanical properties, hydrogels are generally limited for high load-bearing applications. Herein, chitosan and poly(acrylic acid) (PAA) are employed as double networks (DN), and metal-coordination and chain entanglement are exploited as dual crosslinks to develop fully physically crosslinked DN hydrogels. In spite of the non-covalent crosslinking, the hydrogel exhibits impressive tensile properties (3.7 ± 0.12 MPa) and toughness (1200 ± 50% of elongation at break and 2.8 × 103 J m−2 of fracture energy). In addition, good fatigue resistance and self-recovery performance are achieved for the hydrogel because of their supramolecular nature. Notably, the DN hydrogel display good self-healing property with recovered fracture stress and strain of 1.4 MPa and ∼700%, respectively. The results indicate that the supramolecular design proposed in this work can bring more benefits for wide applications of hydrogel.

Strong and tough hydrogels with good self-healing property and processability are of great interest in the recent decades, however, how to simultaneously realize high mechanical properties and self-healing performance still remains a challenge. Here, we report a fully physical dual-network (DN) hydrogel consisting of poly(acrylic acid) (PAA) network crosslinked by ferric ions and chitosan (CS) network crosslinked with calcium ions and chain entanglement. The resulting hydrogel displays a tensile strength of 12.2 MPa and a tensile strain of 1290%. Under the strain of 1000%, 35.7 MJ m−3 of energy can be dissipated by the hydrogel network. Due to the reversibility of the physical crosslinks, particularly, the hydrogel presents high self-recovery and self-healing performances, that is, its tensile strength is recovered to 2.3 MPa after healing. Additionally, even if fragmented, the hydrogel can still acquire a tensile stress of 4.3 MPa after re-processing. This finding indicates the effective strategy to construct high-performance hydrogels can bring benefits to more soft materials.

CO2 replacement is considered as a promising method for the simultaneous development of natural gas hydrate and CO2 sequestration. The addition of small molecular gases, such as N2 and H2, into the injected gas can increase the gas recovery ratio and prevent CO2 liquefaction. Based on previous studies, this work presents methane hydrate exploitation using the CO2/H2 continuous injection-production mode. The mechanism combines gas sweep with CH4/CO2 replacement. A series of experiments were carried out to optimize the injected gas composition and flow rate, which have a significant effect on the rate of CH4 hydrate decomposition, amount of CO2 sequestration, and cost. The compositions of the injected gases had little effect on the recovery rate when a relatively higher flow rate was employed. A balance between CH4 production and CO2 sequestration was established when the CO2 mole fraction was slightly

Saposhnikovia divaricata is a valuable Chinese medicinal herb; the transformation from vegetative growth to reproductive growth may lead to the decrease of its pharmacological activities. Therefore, the study of bolting and flowering for Saposhnikovia divaricata is warranted. The present study aimed to reveal differentially expressed genes (DEGs) and regularity of expression during the bolting and flowering process, and the results of this study might provide a theoretical foundation for the suppression of early bolting for future research and practical application. Three sample groups, early flowering, flower bud differentiation, and late flowering (groups A, B, and C, respectively) were selected. Transcriptomic analysis identified 67, 010 annotated unigenes, among which 50, 165 were differentially expressed including 16, 108 in A vs B, and 17, 459 in B vs C, respectively. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway functional classification analysis were performed on these differentially expressed genes, and five important pathways were significantly impacted (P ≤ 0.01): plant circadian rhythm, other glycan degradation, oxidative phosphorylation, plant hormone signal transduction, and starch and sucrose metabolism. Plant hormone signal transduction might play an important role in the bolting and flowering process. The differentially expressed indole-3-acetic acid (IAA) gene showed significant down-regulation during bolting and flowering, while the transport inhibitor response 1 (TIR1) gene showed no significant change during the bolting process. The expression of flowering related genes FLC, LYF, and AP1 also showed a greater difference at different development stages. In conclusion, we speculate that the decrease in auxin concentration is not caused by the degrading effect of TIR1 but by an alternative mechanism.

Backgroud Recently long non-coding RNAs (lncRNAs) have attracted attention in several biomedical fields. The purpose of this study is to investigate the profile of myocardial lncRNAs and their potential roles in myocardial ischaemia-reperfusion injury (IRI). Methods EdgeR bioconductor package was used to screen differentially expressed lncRNAs in myocardial IRI, and lncRNA AK123483 was selected. The mRNA levels of lncRNA AK123483 in normal and anoxia/reoxygenation (A/R) cardiomyocytes were determined by qRT-PCR. After transfection with siRNA-lncRNA, AK123483, LDH release and cell apoptotic rates in normal and A/R cardiomyocytes were determined. The protein expression values of PARP and Caspase-3 were also determined by western blotting. Results The relative level of lncRNA AK123483, LDH release and cell apoptotic rate in A/R cardiomyocytes was significantly higher than that in normal cardiomyocytes. After transfection with siRNA-lncRNA AK123483, LDH release and cell apoptotic rates in A/R cardiomyocytes were reduced, while the values in normal cardiomyocytes had almost no change. The protein expression values of PARP and Caspase-3 in A/R cardiomyocytes were much higher than the Control. After knockdown of lncRNA AK123483, the values decreased. Conclusion Long non-coding RNAs AK123483 could be potential therapeutic targets for the treatment of myocardial IRI.

Accurate prediction of concrete carbonation is important for the correct assessment of both durability and environmental impact of reinforced concrete (RC) structures. Loading applied to a RC structure and concrete cracking caused by this loading may significantly affect the concrete carbonation process. However, so far these factors have received little attention of researchers, especially this concerns ‘green’ concretes, i.e. concretes in which Portland cement (PC) is partially replaced by supplementary cementitious materials such as fly ash (FA) and ground granulated blast-furnace slag (GGBS). Thus, the aim of the study presented in the paper was to experimentally investigate the influence of static loading and associated concrete cracking on carbonation of RC elements made of PC concretes and ‘green’ concretes containing significant amounts FA and GGBS. For this purpose, six concrete mixes with two water/binder (w/b) ratios (0.40 and 0.55) and different proportions of PC, FA and GGBS were prepared. The mixes were used to cast twelve RC beams (100 × 120 × 900-mm) and a larger number of 100-mm concrete cubes. The beam specimens were loaded in four-point bending to produce flexural cracks of maximum width of either 0.1 mm or 0.3 mm. The loaded beam specimens along with unloaded cube specimens were then placed into a carbonation chamber and subject to accelerated carbonation for 120 days. After that the carbonation depths in the beams and cubes were measured. Results of the tests show a significant effect of load induced stresses (both tensile and compressive) on the carbonation resistance of the concretes, especially of ‘green’ concretes. The influence of cracking on concrete carbonation was also observed and discussed in the paper.

Before performing commercial scale production of natural gas hydrates (NGHs), it is inevitable to estimate the productivity, production period, optimal operation parameters, and further evaluate the technical and economic feasibilities of NGHs field production. The dissociation of gas hydrates is an endothermic process. This needs to compensate additional energy, such as chemical energy, geothermal energy and electricity, etc., in order to keep high dissociation rate. Exergy is a basic parameter that used for various energy systems as a potential tool for design, analysis and optimization. This work provided an exergy analysis method to evaluate the economic efficiency of NGHs exploitation process by brine stimulation combined depressurization method. The input data including cumulative volume of gas production, mass of water production and gas-to-water ratio was obtained by the numerical simulation of TOUGH + HYDRATE. Through the exergy analysis, the total productivity and production period could be determined. These have rarely been reported. The influences of operation parameters, such as well spacing, injection temperature and injection rate of brine on net exergy production were investigated for guiding the set of optimal operating conditions. Since the cost may be one of the biggest challenges for NGHs production, this work suggests making full use of all kinds low-level energy sources to improve energy efficiency, such as brine with high concentration produced by desalination, tidal energy, wind energy, etc.

The spatial difference of hydrate dissociation by depressurization was investigated in an L-shape hydrate simulator to enhance the exploitation efficiency of natural gas hydrates. Hydrates were found to dissociate slower near the mining well than far from the mining well due to the higher water saturation. The mass transfer rate of methane molecules in the water phase was much slower than that in the gas phase. In both vertical and horizontal directions, pore water migrated from the location far from the mining well to that near the mining well in the hydrate reservoir under the pressure difference. This led to a lower dissociation rate for the hydrate distributed at the location near the mining well, which was different from the results in gas/petroleum reservoirs and numerical simulations. The spatial difference was more pronounced in the vertical direction than in the horizontal direction. Gravity caused more water migration in the vertical direction, which led to more uneven dissociation of the hydrates. Sediments with higher permeability and lower mining pressure could result in more pronounced spatial differences. These findings can provide deep insights into the spatial evolution of multiple fields during the exploitation of natural gas hydrates.

The significant discovery of superconductivity in potassium (K) doped polycyclic aromatic hydrocarbons (PAHs) provides a novel system to understand the superconducting mechanism. Here, we focus on K-doped chrysene which is possibly a superconductor. Chrysene contains four benzene rings, however, the superconductivity induced by the K doping has not been discovered. Based on the first-principles calculations with the Van der Waals functional correction, we predicted the geometrical and the electronic structures of K x -doped chrysene ( x =1, 2, 3 and 4). We found that the K doping results in the phase transition from C 2/ c to P 2 1 symmetry. The result of the formation energies shows that K 2 -doped chrysene is the most stable and can easily be fabricated. K 2 chrysene is still a semiconductor, but K 2 chrysene with small charge fluctuation can behave as a metal and is thermodynamically stable. Our results provide a route to experimentally obtain the stable K-doped chrysene with metallic feature.

A novel natural gas hydrate production method combined with methane steam reforming and CO2/H2 replacement was proposed to improve the replacement effect and reduce the cost of later gas separation, in which the role of H2 is to decrease the partial pressure of methane in gas phase and help to break the methane hydrate stability. After preparing representative hydrate sediment samples, we conducted a series of experiments to study the characteristics of gas production by the CH4-CO2/H2 replacement method. For the composition of CO2 and H2 in the feed gas, an increase in the mole fraction of H2 would result in a higher accumulative gas production ratio during the gas sweep and replacement stages but decrease the CO2 sequestration ratio, which refers to the amount of CO2 captured by the hydrate versus the gross CO2 injected into the hydrate layer. On the contrary, an increase in the mole fraction of CO2 in the feed gas would have a higher CO2 sequestration ratio, but would sacrifice both the gas production rate and the accumulative methane production ratio. Notably, when the mole fraction of the CO2 ranges from 55% to 72%, the amount of CO2 trapped into hydrate phase is close to the amount of methane dissociated from hydrate. Although the accumulative gas production ratio is not the highest in this range, it can meet the dual function of CO2 replacement.

Methane dehydroaromatization is a potential technique in converting natural gas into value-added aromatics and clean hydrogen. However, severe coking hinders industrial application of conventionally prepared Mo/ZSM-5 catalyst for methane dehydroaromatization. Usually, Bronsted acid sites (BAS) were considered the key for coking. To gain deeper insight into the coke, here we present a simple post-impregnation of Na+ to Mo/HZSM-5 to regulate its surface acidity. Influences of BAS on catalytic performance and coking behavior were thus exclusively studied. Na+ modified catalysts exhibit lower naphthalene and higher C2 selectivity, while selectivity for benzene is not obviously changed. These results contradict conventional bi-functional pathway that methane is dehydrogenated on Mo while BAS act as the center for intermediates cyclization. Characterizations and calculations indicate restricted growth of hydrocarbon pools confined in zeolite channels of Na+ modified catalysts. Hence, it is proposed that aromatization is the intrinsic property of Mo, and the Mo-associated carbonaceous species act as precursors for both coke and aromatics production.

Disastrous concrete cracks as initiated by rebars pit corrosion and the resulted rust expansion have continually threatened the vitality of the reinforced concrete structures. In investigating the effects attributed to the rust expansion, existing scholastic works have, however, either focused only on examining one type of major crack or disregarded the influence of the external loading. Therefore, various contesting crack modes of the reinforced concrete structure due to rust progressive expansion from the rebars pit corrosion under external load are analytically modeled in this paper. To begin, such a multi-factors incident has been formulated under the premise of a thick cylindrical section with plane strain conditions and the new consideration of external loading. Considered major contesting crack modes include those of vertical, diagonal, and horizontal. Furthermore, a novel experimentally complying expansion ratio relating the rust expansion with the corrosion penetration depth is introduced into the model. Concrete cover thicknesses are categorized via the fracture mechanics process zone length, LFPZ, in determining the crack mode. In conclusion, thin covers are dominated by the vertical crack whereas thicker covers may crack diagonally or horizontally, depending on LFPZ and the crack tip deformation state. The rust expansion reduces both the moment capacity and the critical crack time to reach the concrete cover surface. tcr, while the critical corrosion penetration depth increases with the concrete cover thickness. However, the horizontal crack when dominating can offset this concrete cover effect by significantly reducing tcr. Additionally, the rust expansion affects the concrete cracking more than the external load.

To better understand the process that hydrocarbon gas moves through permeable conduits into the gas hydrate stability zone, a hydrate formation system, mainly composed by a tube reactor, was designed and constructed. The influence factors, such as pressure, temperature, and gas flux, have been investigated. Here also providing a method to measure the induction time of hydrates formation in sandy sediments by analyzing the gas flow rate and pressure drop. Either increasing pressure or reducing temperature can shorten the induction time and improve hydrate formation rate. A percolation model was established to investigate the variation of physical properties of the sediments caused by hydrates formation from seepage gas. The results show that hydrate does not uniformly generate in the whole space of the sediments, but quickly nucleate and accumulate in part of the pore space. With the formation of hydrate, the channel of gas migration could be blocked, and the porosity and permeability of sediments would reduce accordingly.

In the present paper, five-time electrochemical impedance spectroscopy (EIS) data of uncoated and epoxy coated-bars in RC test specimens subjected to pre-exposure loading and three wetting-drying cycles are reported. Variation of electrochemical data of the reinforcing bars with cycle time is shown basing on the test results. On the basis of electrical equivalent circuits fitting results, variation of coating resistance of the coated-bars with cycle time is presented. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) results of the cross section of the samples used are also presented. The influence of pre-exposure loading on the corrosion behavior of reinforcing bars in RC test specimens is mainly discussed on the basis of pre-exposure loading results, EIS fitting results as well as SEM and EDS results. Based on this discussion, a deterioration mechanism of corrosion resistance of epoxy-coated bars in RC elements subjected to in-service loads and environmental attacks simultaneously, is proposed. It is concluded that coating adhesion and corrosion resistances of epoxy coated-bars are greatly influenced by pre-exposure loads and simulated seawater solution attacks, especially in zones where coat-bars are highly stressed and load-induced cracks in concrete cover are wide.

A novel photoluminescent glucose nanosensor was facilely prepared by coupling glucose oxidase (GOx) with poly- l -lysine coated oxygen nanosensors via a glutaraldehyde-mediated Schiff-base reaction. The GOx molecules residing on particle surface catalyzed glucose with the expense of oxygen, which was detected by the sensing particle core incorporated with the reference dye coumarin 6 and oxygen probe Pt(II)-meso-tetra(pentafluorophenyl)porphine. The proposed glucose nanosensors (∼150 nm in hydrodynamic diameter) had a quick response time varied from less than 2 min to 4 min. Glucose calibration was performed with ratiometric photoluminescence and time-resolved fluorescence (TRF) respectively, and a series of calibration plots were constructed according to determination time. In comparison, the ratiometric method resulted in wide dynamic range (e.g. 2–10 mM) and high limit of detection (∼1–2 mM), while the TRF mode gave narrow dynamic range (e.g. 1–6 mM) with low detection limit (∼0.1–0.2 mM). Finally the enzymatic glucose nanosensors were tested in human serum samples with a TRF microplate reader.

Natural gas hydrates (NGHs) are considered to be promising alternative future energy sources due to their large reserves in oceans and permafrost zones. However, the hydrate sediment characteristics in different regions are varied, which determines the feasibility of NGHs exploitation. Accurate knowledge of the accumulation behavior of NGHs is the basis for their exploration and exploitation. In this study, we comprehensively review the relevant gas hydrate accumulation studies including the NGH resources and morphologies, different hydrate accumulation conditions and patterns, current experimental research progress, and thermodynamic and kinetic models for hydrate formation in porous sediments. Based on the studies of NGH accumulation, we discuss the current limitations and challenges and put forward some suggestions from our points of view.

The relationship between the hydrate-bearing sediments with physical properties such as wave velocity is of importance for the exploration and exploitation of natural gas hydrate. The distribution modes of naturally occurring gas hydrates in sediments are diverse and have significant influence on physical properties of rocks. However, hydrates in homogeneous distribution are in general investigated in laboratory currently. In this work, to simulate the diverse distribution modes of naturally occurring gas hydrates, a novel method to prepare the hydrate-bearing sediments with heterogeneous distribution including layered distribution was proposed by controlling the temperature, water migration, and water saturation distribution. Velocity and amplitude of P-wave are investigated to evaluate the physical properties of hydrate-bearing sediments with homogeneous or heterogeneous distribution. The results showed that the hydrate formation process apparently consists of unconsolidated and consolidated steps according to the amplitude curve. The amplitude of P-wave in the unconsolidated stage increases slowly, while it increases suddenly and rapidly in the consolidated stage. The P-wave velocity of the hydrate deposits with homogeneous distribution is faster than that with heterogeneous distribution when under a same hydrate saturation. This is also verified from the experiments performed on hydrate-bearing sediments with layered distribution, which provided direct evidence and quantification about heterogeneous degree of hydrate distribution in sediment. This difference of the P-wave velocity between heterogeneous and homogeneous hydrate-bearing sediments would provide a guidance in the future development of natural gas hydrate.