Search

Most mature reservoirs in China are facing severe conformance problems causing excessive water production, high water cuts, and low recovery factors due to the severe heterogeneity. Among these conformance problems, high-conductivity channels, such as large fractures and void space conduits, could cause fast communication between injection and production wells, limiting the sweep efficiency. Therefore, plugging high-conductivity channels plays a crucial role in water/gas flooding and the enhanced oil recovery process. This work systematically elucidates several commonly used plugging agents, including their basic compositions and properties. We summarized the field pilot results and came up with the current problems and several suggestions for the further development direction of plugging agents. Hopefully, this work could provide valuable guidance for plugging high-conductivity channels in mature reservoirs.

Transition metal dichalcogenide (TMD) heterobilayers have emerged as a promising platform for exploring solid-state quantum simulators and many-body quantum phenomena. Their type II band alignment, combined with the moiré superlattice, inevitably leads to nontrivial exciton interactions and dynamics. Here, we unveil the distinct Auger annihilation processes for delocalized interlayer excitons in WS2/WSe2moiré heterobilayers. By fitting the characteristic efficiency droop and bimolecular recombination rate, we quantitatively determine an ultralow Auger coefficient of 1.3 × 10–5cm2s–1, which is >100-fold smaller than that of excitons in TMD monolayers. In addition, we reveal selective exciton upconversion into the WSe2layer, which highlights the significance of intralayer electron Coulomb interactions in dictating the microscopic scattering pathways. The distinct Auger processes arising from spatial electron–hole separation have important implications for TMD heterobilayers while endowing interlayer excitons and their strongly correlated states with unique layer degrees of freedom.

The present study simulated the actual contact conditions between the catenary and pantograph of a metro line using high-speed ring block current that carried friction and wear testers, from which the uneven wear of the pantograph carbon strip under different working conditions was studied. The results show that the arc power, friction coefficient, and wear amount will change correspondingly with increasing current and normal load. Additionally, all carbon strips showed non-uniform wear after the test, and the edge erosion and wear depth of the carbon strip perpendicular to the moving direction were higher than those in the middle part. The ablation of the back end of the carbon strip running with the catenary was higher than that of the front end.

The catalytic carbon monoxide (CO) methanation is an ideal model reaction for the fundamental understanding of catalysis on the gas–solid interface and is crucial for various industrial processes. However, the harsh operating conditions make the reaction unsustainable, and the limitations set by the scaling relations between the dissociation energy barrier and dissociative binding energy of CO further increase the difficulty in designing high-performance methanation catalysts operating under milder conditions. Herein, we proposed a theoretical strategy to circumvent the limitations elegantly and achieve both facile CO dissociation and C/O hydrogenation on the catalyst containing a confined dual site. The DFT-based microkinetic modeling (MKM) reveals that the designed Co-Cr2/G dual-site catalyst could provide 4–6 orders of magnitude higher turnover frequency for CH4production than the cobalt step sites. We believe that the proposed strategy in the current work will provide essential guidance for designing state-of-the-art methanation catalysts under mild conditions.

Graphical Abstract:

Peroxisome proliferator-activated receptor alpha (PPARα) activation-induced hepatomegaly is accompanied by hepatocyte hypertrophy around the central vein (CV) area and hepatocyte proliferation around the portal vein (PV) area. However, the molecular mechanisms underlying this spatial change of hepatocytes remains unclear. In this study, we examined the characteristics and possible reasons for the zonation distinction of hypertrophy and proliferation during PPARα activation-induced mouse liver enlargement. Mice were injected with corn oil or a typical mouse PPARα agonist WY-14643 (100 mg·kg−1·d−1, i.p.) for 1, 2, 3, 5 or 10 days. At each time point, the mice were sacrificed after the final dose, and liver tissues and serum were harvested for analysis. We showed that PPARα activation induced zonal changes in hepatocyte hypertrophy and proliferation in the mice. In order to determine the zonal expression of proteins related to hepatocyte hypertrophy and proliferation in PPARα-induced liver enlargement, we performed digitonin liver perfusion to separately destroy the hepatocytes around the CV or PV areas, and found that PPARα activation-induced increase magnitude of its downstream targets such as cytochrome P450 (CYP) 4 A and acyl-coenzyme A oxidase 1 (ACOX1) levels around the CV area were higher compared with those around the PV area. Upregulation of proliferation-related proteins such as cell nuclear antigen (PCNA) and cyclin A1 (CCNA1) after WY-14643-induced PPARα activation mainly occurred around the PV area. This study reveals that the zonal expression of PPARα targets and proliferation-related proteins is responsible for the spatial change of hepatocyte hypertrophy and proliferation after PPARα activation. These findings provide a new insight into the understanding of PPARα activation-induced liver enlargement and regeneration.

The Sabatier principle defines the essential criteria for being an ideal catalyst in heterogeneous catalysis, while approaching the Sabatier optimal is a major pursuit in catalyst design. The Haber–Bosch (H-B) process, converting nitrogen (N2) and hydrogen (H2) to ammonia (NH3), is a holy grail reaction for humans and also a great model reaction for fundamental research, where the established volcano plot between ammonia synthesis activity and nitrogen binding energy among metals has successfully guided new catalyst design. However, reaching the top of the activity volcano is still very challenging. Herein, we identify an elegant strategy to promote the ferromagnetic (FM) catalysts to be the Sabatier optimal of ammonia synthesis via a second-order ferromagnetic–paramagnetic phase transition, which represents an ideal and novel interdisciplinary of the aforementioned century-old classic principle, reaction, and theory in chemistry, physics, and material science. The paramagnetic (PM) Co and Ni metals could have 2–4 orders of magnitude higher ammonia synthesis activity than their ferromagnetic counterparts, holding the potential to achieve a near-ambient H-B process. We believe that our discovery will open a novel avenue for revisiting the catalytic performances of paramagnetic phases of ferromagnetic materials in heterogeneous catalysis.

A hard and thick surface strengthening layer with high interfacial bonding strength was innovatively prepared via self-propagating high temperature synthesis (SHS) combined with hot pressing sintering (HPS) process. The thickness of the surface layer reached 1.1 mm, far exceeding the strengthening layer prepared by the traditional surface modification methods of titanium alloy. The raw materials of the hard layer were carefully designed by mixing powders of Ti, C, B and Ni, and the raw material of the matrix was Ti–6Al–4V powder. During the HPS process (1100 °C, 40 MPa), the Ti–Ni reaction released a large amount of heat, which promoted the Ti–C reaction and Ti–B reaction. The test results of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) suggested that a high amount of Ti6C3.75and TiB were finally generated in the hard layer, and the Vickers hardness value was as high as 1800 HV. Furthermore, the energy dispersive spectrometer (EDS) test results indicated that most Ni atoms diffused to the Ti–6Al–4V side, and NiTi2phase was mainly distributed at the interface. Obviously, metallurgical bonding was obtained, accounting for the high interfacial bonding strength of 162 MPa. The present work provided significant insights into the design of novel titanium alloy surface modification process.

Cisplatin is the first-line drug for treatment of various solid tumors including breast cancer due to the broad anti-tumor spectrum and strong anti-tumor effect. However, serious side effects and long-term medication of reduced sensitivity by high GSH in tumor cells have severely restricted its further clinical application. Herein, a GSH-depleted Pt(IV) prodrug (Platin B) based on cisplatin and 4-carboxylphenylboronic acid pinacol ester was prepared to solve the problems. As an excellent GSH scavenger, 4-carboxylphenylboronic acid pinacol ester could be activated by intracellular redox reactions to release quinone methide, thereby amplifying oxidative stress and leading to breast cancer ferroptosis therapy. Interestingly, the consumption of GSH can also reduce cisplatin inactivation, enhance the sensitivity of tumor cells to cisplatin and efficiently induce apoptosis/ferroptosis. This work highlights the use of GSH scavenger for triggering ferroptotic cell death in breast cancer.

The application of organic small molecules as metal-free photocatalysts for light-driven photoreduction of carbon dioxide (CO2) has seldom been explored. This work developed four naphthalene diimide (NDI)-derived donor–acceptor–donor small molecules with different numbers of thiophene units, namely, NDI-2T, NDI-TT, NDI-4T, and NDI-6T, as metal-free photocatalysts to catalyze the reduction of CO2under irradiation with an air mass 1.5G solar simulator at one-sun intensity. The structure–property relationship was investigated by exploring the effects of the electron-donating ability of the donor units on the optical properties, redox potential, electron–hole distribution, and exciton lifetime. NDI-6T exhibited the most red-shifted absorption, longest exciton lifetime, and strongest electron–hole separation. However, the large upshift in oxidation potential because of the elevated electron-donating ability of the hexathiophene unit significantly reduced the driving force for catalyst regeneration, leading to poor catalytic performance. Alternatively, NDI-4T possessed proper redox potentials, reduced charge-transfer resistance, and excellent photocurrent intensity; therefore, it effectively converted CO2to a single product of CO in the presence of water as an electron donor without a sacrificial reagent or cocatalyst with a product yield of 168.6 μmol gcat–124 h–1, which was considerably higher than those of NDI-TT (111.9 μmol gcat–124 h–1), NDI-2T (88.4 μmol gcat–124 h–1), and NDI-6T (40.5 μmol gcat–124 h–1). This study provides a practical guideline for the molecular design of conjugated organic molecules as promising photocatalysts for CO2photoreduction.

Nowadays, the photochemical conversion of CO2to high-value products is attracting tremendous research interest. Developing artificial photocatalysts with excellent catalytic activity and long-term stability is still a challenge. This work demonstrates that solution-processable naphthalenedimide (NDI)-based conjugated polymers, PNDI-BT, PNDI-DTBT, and PNDI-BP, which are copolymerization products of NDI with bithiophene (BT), 4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (DTBT), and biphenyl (BP), respectively, were capable of catalyzing the photochemical reduction of CO2to produce CO in the presence of water without the need for metal-containing co-catalysts or sacrificial agents. In particular, the PNDI-BP-catalyzed reaction generated CH4as well as CO. Results from time-resolved photoluminescence, photovoltage decay, electrochemical impedance spectroscopy, and transient photocurrent response experiments indicate that PNDI-BP with the largest dihedral angles along the conjugated backbone possessed the longest electron lifetime, the lowest charge-carrier recombination rate, and the smallest interfacial charge transfer resistance. Consequently, it had the best catalytic performance. Notably, PNDI-BP exhibited excellent recyclability, robust structural stability, and extremely steady catalytic activity for more than 330 h during a photocatalytic CO2reaction. Furthermore, the solution-processability of the linear polymer allows the incorporation of porous substrates, which improve the reaction interface. The catalyst system of PNDI-BP@molecular sieves with H2O/triethylamine doubled the CO yield to 214.8 μmol·gcat–1and enhanced the CH4yield by ∼36 times to 61.4 μmol·gcat–1in an 18 h reaction.

In southern China, co-incorporating winter green manure and rice straw has proven to be a practical and economically viable strategy that enhances soil carbon (C) sequestration and agricultural productivity in rice paddies. However, the issue of how to control the greenhouse gas (GHG) emissions in paddy fields owing to the incorporation of substantial organic matter remains a bottleneck. A 2-year field experiment was conducted, which included five treatments: conventional water management with no residue (CK) and with co-incorporation of green manure and rice straw (GM+Rs), delayed flooding by 5, 10, and 15 days after the co-incorporation of green manure and rice straw (GM+Rs-DW5, GM+Rs-DW10, and GM+Rs-DW15) before transplanting rice seedlings. The delayed flooding treatments reduced the 2-year average CH4emissions by 40.9%–60.8% compared with GM+Rs. The delayed flooding inhibited the growth of methanogens and CH4emissions, which was linked to a reduction of dissolved organic carbon (DOC) concentration in surface water. The lowest C footprint (4.05 t CO2-eq ha−1) as well as the yield-scaled C footprint (0.6 kg CO2-eq kg−1) were observed in the GM+Rs-DW10 treatment, both even lower than those in CK (15.11 t CO2-eq ha−1and 2.1 kg CO2-eq kg−1). Moreover, the GM+Rs-DW10 treatment led to an increase in net ecosystem economic benefit (NEEB) of 3750 and 2870 CNY ha−1than CK and GM+Rs over a 2-year period. Collectively, delayed flooding with green manure and rice straw incorporation is conducive to achieving high NEEB and low risk of GHG emissions. This finding provides important and novel insights for eco-efficient rice production.

In this study, a modeling method for investigating the dynamic characteristics of a hydraulically driven shell manipulator with revolute clearance joints is presented. This model accounts for the effect of the clearance, the flexibility of the rotating beam, and the coupled dynamic characteristics of the hydraulic cylinder. A modified contact force model was developed to simulate the physical properties of realistic revolute joints with small clearances, heavy loads, and variable contact stiffnesses and damping coefficients with variations of the indentations. Considering the strong coupling relationship between the hydraulic cylinder and the flexible beam, a system equation of motion combining the state variables of the hydraulic cylinder and mechanical system was established. The complex nonlinear friction force of the hydraulic cylinder motion was constructed using a modified LuGre model, and the parameters of the friction model were identified using intelligent identification algorithms. Moreover, a test system for the shell manipulator was established to achieve experimental validation. Finally, the effects of the clearance size and the stiffness of the cylinder support on the dynamic response were investigated.

Selective removal of ∼1% acetylene impurity from ethylene is an essential process to prevent the poisoning of the Ziegler–Natta catalyst in polyethylene production. Developing an earth-abundant catalyst to replace Pd and a new approach to reduce energy consumption represents an immense challenge in this field. Herein, we present an atomic understanding of the trend in electrocatalytic acetylene semi-hydrogenation over 12 transition metals with systematic density functional theory calculations and the computational hydrogen electrode model. Copper stands out and is theoretically identified as the ideal metal for electrocatalytic acetylene conversion to ethylene with a suppressed hydrogen evolution reaction. Our theoretically predicted Cu catalyst has been successfully synthesized and tested to be superior for selective alkyne semi-hydrogenation experimentally, which greatly validates our computational framework for the rational design of the catalyst. This work not only illustrates the key factors determining the activity and selectivity but also provides new suggestions for further optimization of this environmentally benign and economically feasible route for ambient alkyne semi-hydrogenation.

ObjectiveTricuspid regurgitation (TR) is a common valvular heart disease with unsatisfactory medical therapeutics and high surgical mortality. The present study aims to evaluate the safety and effectiveness of transcatheter tricuspid valve replacement (TTVR) in high-risk patients with severe TR.MethodsThis was a compassionate multicentre study. Between September 2018 and November 2019, 46 patients with TR who were not suitable for surgery received compassionate TTVR under general anaesthesia and the guidance of trans-oesophageal echocardiography and fluoroscopy in four institutions. Access to the tricuspid valve was obtained via a minimally invasive thoracotomy and transatrial approach. Patients’ data at baseline, before discharge, 30 days and 6 months after the procedure were collected.ResultsAll patients had severe TR with vena contracta width of 12.6 (11.0, 14.5) mm. Procedural success (97.8%) was achieved in all but one case with right ventricle perforation. The procedural time was 150.0 (118.8, 180.0) min. Intensive care unit time was 2.0 (1.0, 4.0) days. 6-month mortality was 17.4%. Device migration occurred in one patient (2.4%) during follow-up. Transthoracic echocardiography at 6 months after operation showed TR was significantly reduced (none/trivial in 33, mild in 4 and moderate in 1) and the primary safety end point was achieved in 38 cases (82.6%). Patients suffered from peripheral oedema and ascites decreased from 100.0% and 47.8% at baseline to 2.6% and 0.0% at 6 months.ConclusionsThe present study showed TTVR was feasible, safe and with low complication rates in patients with severe TR.

Exposure therapy based on the extinction of fear memory is first-line treatment for post-traumatic stress disorder (PTSD). However, fear extinction is relatively easy to learn but difficult to remember, extinguished fear often relapses under a number of circumstances. Here, we report that extinction learning-induced association of neuronal nitric oxide synthase (nNOS) with its carboxy-terminal PDZ ligand (CAPON) in the infralimbic (IL) subregion of medial prefrontal cortex negatively regulates extinction memory and dissociating nNOS-CAPON can prevent the return of extinguished fear in mice. Extinction training significantly increases nNOS-CAPON association in the IL. Disruptors of nNOS-CAPON increase extracellular signal-regulated kinase (ERK) phosphorylation and facilitate the retention of extinction memory in an ERK2-dependent manner. More importantly, dissociating nNOS-CAPON after extinction training enhances long-term potentiation and excitatory synaptic transmission, increases spine density in the IL, and prevents spontaneous recovery, renewal and reinstatement of remote fear of mice. Moreover, nNOS-CAPON disruptors do not affect other types of learning. Thus, nNOS-CAPON can serve as a new target for treating PTSD.

Chronic hepatitis B (CHB) patients who had exposed to lamivudine (LAM) and telbivudine (LdT) had high risk of developing entecavir (ETV)-resistance after long-term treatment. We aimed to conduct a systematic review and a network meta-analysis on the efficacy and cost-effectiveness on antiviral regimens in CHB patients with ETV-resistance.

A broadband and low-dispersion high refractive index (HRI) metamaterial formed by symmetrically etching two identical metasurfaces on both sides of a dielectric slab has been numerically and experimentally demonstrated in the terahertz region. The unit cell of the metasurface is a Jerusalem cross surrounded by a square metal ring, in which there are two magnetic resonances and one electric resonance. The proposed metamaterial simultaneously possesses high effective permittivity and permeability in broadband frequencies, since the multiple resonances result in a significant bandwidth expansion of a HRI. The simulation results reveal that the refractive index of the proposed metamaterial reaches up to 27 in the frequency range of 0.39–0.65 THz, and the relative bandwidth is about 44%. Furthermore, the fluctuation of the refractive index in this frequency band is less than 6%, showing a good low-dispersion characteristic. We also fabricated a sample to verify this HRI property. Experimental results are in good agreement with numerical simulations. This broadband HRI metamaterial is desirable in many fields, such as in high-resolution imaging and optical communications.

An efficient and mild method for reductive C–O bond cleavage of lignin β-O-4 ketone models was developed to afford the corresponding ketones and phenols with PDI-CoCl2as the precatalyst and diboron reagent as the reductant. The synthetic utility of the methodology was demonstrated by depolymerization of a polymeric model and gram-scale transformation. Mechanistic studies suggested that this transformation involves steps of carbonyl insertion, 1,2-Brook type rearrangement, β-oxygen elimination, and rate-limiting regeneration of the catalytic active Co–B species.

An efficient cobalt-catalyzed Zto Eisomerization of β-substituted styrenes using the amido-diphosphine ligand was developed, delivering the (E)-isomers with good functional tolerance and high stereoselectivity. The reaction could be scaled up to gram-scale with a catalyst loading of 0.1 mol %, using a mixture of (Z)- and (E)-alkene as the starting material. Preliminary mechanistic studies indicated that cobalt(I)-hydride and a benzylic-cobalt species were probably involved in the reaction, as supported by experiments and DFT calculations.

Four surface-modified and, hence, positively charged metal nanoparticles (NPs) of different localized surface plasmon (LSP) resonance wavelengths are synthesized for linking with negatively charged, red-emitting colloidal CdZnSeS/ZnS quantum dots (QDs) on the top surface of a blue-emitting InGaN/GaN quantum well (QW) light-emitting diode (LED) through electro-static force. The metal NP-QD linkage leads to a short distance between them for producing their strong surface plasmon (SP) coupling, such that QD absorption and emission can be enhanced. Meanwhile, the small p-GaN thickness in the LED results in strong SP coupling between the LSP resonance of metal NP and the QWs of the LED, leading to enhanced QW emission and, hence, stronger QD excitation. All those factors together result in the increase of the color conversion efficiency of the QD.

Lignosulfonate (LS) had various influences on the enzymatic digestibility of lignocelluloses for the complicated structure of LS. The effect of the complex of LS and cationic surfactant cetyltrimethylammonium bromide (LS–CTAB) on the enzymatic digestibility of corn stover and Avicel was investigated in this study. The LS–CTAB catanionic surfactant could significantly improve the enzymatic digestibility of Avicel and corn stover from 42.1 and 24.3% to 62.3 and 56.2%, respectively. In addition, the effect of LS–CTAB with various molecular weights and sulfonation degrees of LS and varied alkyl chain lengths of CnTAB on the enzymatic digestibility of Avicel was further investigated to reveal that the mechanism of LS–CTAB enhanced the enzymatic digestibility of cellulose. LS adsorbed on cellulase aggregates and dispersed the aggregates to form the smaller and more hydrophilic LS–cellulase aggregates. CTAB neutralized the electronegative charge of LS–cellulase aggregates, improved the interaction between cellulase and cellulose, and enhanced the enzymatic digestibility of cellulose.

Au nanotube-based composite membrane served as surface-enhanced Raman scattering (SERS) substrate with an ultralarge aspect ratio possesses an excellent flexibility and widely tunable surface plasmon resonance, and by introducing graphene oxide (GO) as a spacer layer, the SERS enhancement of the composite membrane is obviously better than those from the individual blocks of the Au nanotubes (AuNTS) membrane and the Au nanoparticle/graphene oxide (AuNP/GO) membrane. Such a “sandwich” (AuNP/GO/AuNT) structured membrane has a high SERS sensitivity and a wide tunability by controlling the size of Au nanoparticles and the thickness of graphene oxide, and the detection limits of the AuNP/GO/AuNT substrate for R6G and NBA are as low as 10–12and 10–7M, respectively; the large enhancement is attributed to the adsorption and chemical mechanism of graphene oxide and the physical mechanism of the Au nanoparticles and nanotubes (the electromagnetic field coupling between them).

This study assessed trends in the incidence of cardiovascular implantable electronic device (CIED) infection in the last 3 decades using a population-based records linkage study.

A lignin amphoteric surfactant and betaine could enhance the enzymatic hydrolysis of lignocellulose and recover cellulase. The effects of lignosulfonate quaternary ammonium salt (SLQA) and dodecyl dimethyl betaine (BS12) on enzymatic hydrolysis digestibility, ethanol yield, yeast cell viability, and other properties of high-solid enzymatic hydrolysis and fermentation of a corncob residue were studied in this research. The results suggested that SLQA and 1 g/L BS12 effectively improved the ethanol yield through enhancing enzymatic hydrolysis. SLQA had no significant effect on the yeast cell membrane and glucose fermentation. However, 5 g/L BS12 reduced the ethanol yield as a result of the fact that 5 g/L BS12 damaged the yeast cell membrane and inhibited the conversion of glucose to ethanol. Our research also suggested that 1 g/L BS12 enhanced the ethanol yield of corncob residue fermentation, which was attributed to the fact that lignin in the corncob adsorbed BS12 and decreased its concentration in solution to a safe level for the yeast.