Search

• A nanocatalyst@superhydrophilic composite coating (CMP-Ti) was constructed on the medical titanium surface. • Nanocatalysts (CM NRs) on the CMP-Ti surface can induce ferroptosis-like death in drug-resistant bacteria. • CMP-Ti resists the initial adhesion of bacteria, thus preventing biofilm formation. • CMP-Ti can prevent multimodal implant-associated infections caused by drug-resistant bacteria. Implant-associated infections (IAIs) caused by drug-resistant bacteria remain a critical factor in the failure of implant procedures. Therefore, it is urgent to develop an effective anti-infection coating for implant surface modification to prevent IAIs. Herein, an antibacterial and anti-adhesive coating (CMP-Ti) constructed on the surface of titanium implants is reported, formed by the nanomaterial CeO 2 @Mn 3 O 4 NRs (CM NRs) with antibacterial activity and the superhydrophilic polymer polyethylene glycol (PEG). The nanocatalyst CM NRs on the surface of CMP-Ti induce ferroptosis-like death of bacteria by catalyzing the production of hydroxyl radical (•OH) and singlet oxygen (1O 2) and the consumption of glutathione (GSH). The superhydrophilic coating of CMP-Ti can effectively prevent adherence of drug-resistant bacteria and avoid biofilm formation. By combining the "active offense" antibacterial mechanism with the "passive defense" anti-adhesion mechanism, CMP-Ti can kill bacteria and inhibit biofilm formation. The results of in vivo studies showed that CMP-Ti effectively prevented implant-associated infections caused by Methicillin-resistant Staphylococcus aureus (MRSA), thus promoting tissue repair and osseointegration. Therefore, this multifunctional coating combining "active offense" and "passive defense" provides a promising way to prevent IAIs caused by drug-resistant bacteria and to promote tissue repair in the future. An antibacterial and anti-adhesive coating was prepared on the surface of a medical titanium implant. The composite coating can induce the ferroptosis-like death of drug-resistant bacteria and prevent biofilm formation, thus effectively preventing implant-associated infections caused by drugresistant bacteria. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphical abstract:

AbstractThe evaluation of event impact is practical and helpful in increasing event quality. From residents’ positive points of view, hosting sporting events brings both the community and the country together, increases investment, and stimulates administrative pollution controls. As such, scales were developed to assess various impacts associated with sporting events. However, some psychometric information is missing in existing event impacts research. The purpose of this study is to illustrate how to use Item Response Theory (IRT) to measure positive event impacts. The sample (N = 423) was collected between May 14 and May 31, 2014, before the commencement of the Nanjing Youth Olympic Games in China. Positive event impacts measurements from both Prayag, Hosany, Nunkoo, and Alders (2013) and Ma, Ma, Wu, and Rotherham (2013) were revised. The results indicate that the IRT approach yields invariant item parameters (i.e., discrimination and difficulty). In addition, advantages and utility of IRT in the sporting event context are discussed.

Titanium (Ti) and its alloys are extensively applied in dental and orthopedic implants due to their characteristics of good mechanical property and corrosion resistance. However, Ti and its alloys suffer from the absence of certain biological activity and antibacterial ability. Herein, we synthesized a titanium dioxide (TiO2) nanorod array on the surface of a Ti plate, and the obtained TiO2nanorod array was further modified by Cu ions through ion implantation technology in an attempt to endow medical Ti with an antibacterial ability and maintain a normal biological function synchronously. The antibacterial ability of the TiO2nanorod array with the incorporation of Cu ions was vastly improved compared with those of the unmodified TiO2nanorod array and pure Ti. In particular, owing to the synergy between the chemical damage of the released Cu2+to the cell and the mechanical cracking of the TiO2nanorod array, the antibacterial rate of the TiO2nanorod array modified by Cu ions against Escherichia colior Staphylococcus aureuscould reach 99%. In addition, no cytotoxicity was detected in such prepared coating during the CCK-8 assay. Moreover, the corrosion resistance of the sample was significantly better than that of pure Ti. Overall, we demonstrated that the application of ion implantation technology could open up a promising pathway to design and develop further antibacterial material for the biomedical domain.

Natural polymer gels with sensitivity to near-infrared (NIR) light have attracted the attention of scientists working on intelligent drug delivery systems. Compared to ultraviolet or visible light, NIR light has the advantages of strong trigger levels, deep penetration through affected tissues, and fewer side effects. Herein, we present a topical photothermal hydrogel for NIR-controlled drug delivery. The proposed DexIEM-GM-Laponite hydrogel was prepared through free radical polymerization of vinyl-functionalized dextran (DexIEM), vinyl-modified graphene oxide (GM), and Laponite; thereafter, the hydrogel was loaded with ciprofloxacin (CIP, an antibacterial drug) as a model drug. With the Laponite content increased, the density of crosslinking in the hydrogel increased, and its mechanical properties improved noticeably. Under NIR irradiation, the DexIEM-GM-Laponite hydrogel exhibited a photothermal property, where the surface temperature increased from 26.8 to 55.5 °C. The simulation of subcutaneous drug delivery experiments ex vivo showed that under the specified pork tissue thickness (2, 4, and 6 mm), the CIP release remained NIR-controllable. Additionally, the results of the antibacterial performance tests indicated the excellent antibacterial effect of the hydrogel, and the blood hemolysis ratio of the hydrogel was less than 5%, signifying good blood compatibility. This work will provide an avenue for the application of NIR light-responsive materials in antimicrobial therapy.

Frustrated Lewis pairs (FLPs) containing sterically hindered Lewis acidic and basic sites can capture and react with N2and CO2, thus furnishing a new strategy for urea electrosynthesis. Herein, the rice-like InOOH nanoparticles coupled with the well-defined FLPs (i.e., In In-OH) were synthesized and exhibited a urea yield rate of 6.85 mmol h−1g−1and faradic efficiency of 20.97% at −0.4 V versus reversible hydrogen electrode. Systematic investigations reveal that the electron-deficient Lewis acidic In sites and electron-rich Lewis basic In-OH achieve the targeted chemisorption of the N2and CO2molecules by electronic interaction respectively. The bonding and antibonding orbitals of reactant molecules interact with the unoccupied orbitals of Lewis acid and nonbonding orbitals of Lewis base to generate the desired intermediates for urea synthesis in artificial FLPs. In addition, FLPs can further ensure the orbital-matched intermediates of ∗N=N∗ and CO proceed with the desirable C–N coupling reaction to produce ∗NCON∗ precursors.

Oxygen evolution reaction (OER) as the foremost stumbling block to generate cost-effective clean fuels has received extensive attention in recent years. But, it still maintains the challenge to manipulate the geometric and electronic structure during single reaction process under the same conditions. Herein, we report a simple self-template strategy to generate honeycomb-like Ni2P/N,P–C hybrids with preferred electronic architecture. Experiments coupled with theoretical results revealed that the synthesized catalyst has two characteristics: firstly, the unique honeycomb-like morphology not only enables the fully utilization of catalytic active sites but also optimizes the mass/electron transportation pathway, which favor the diffusion of electrolyte to accessible active sites. Secondly, N,P–C substrate, on the one hand, largely contributes the electronic distribution near Fermi level (EF) thus boosting its electrical conductivity. On the other hand, the support effect result in the upshift of d-band center and electropositivity of Ni sites, which attenuates the energy barrier for the adsorption of OH−and the formation of ∗OOH. In consequence, the optimized Ni2P/N,P–C catalysts feature high electrocatalytic activity towards OER (a low overpotential of 252 mV to achieve 10 mA cm−2) and 10 h long-term stability, the outstanding performance is comparable to most of transition metal catalysts. This work gives a innovative tactics for contriving original OER electrocatalysts, inspirng deeper understanding of fabricating catalysts by combining theoretical simulation and experiment design.

Microbial contamination and the prevalence of resistant bacteria is considered a worldwide public health problem. Therefore, recently, great efforts have been made to develop photoresponsive platforms for the simultaneous photodynamic antibacterial (PDA) and photothermal antibacterial (PTA) therapy processes as mediated by specific light. However, owing to the absorption mismatches of the photothermal agents and photodynamic photosensitizers, it has been discovered that many synergistic photoresponsive antibacterial platforms cannot be excited by a single-wavelength light. In this study, silver bismuth sulfide quantum dots (AgBiS2QDs) identified from the literature as a near-infrared light (NIR) that triggers bifunctional materials with simultaneous photodynamic and photothermal effects for photoresponsive bacterial killing were used. Specifically, AgBiS2QDs were successfully synthesized via a bottom-up approach, using polyethylenimine (PEI) as an assistant molecule. With PEI wrapping, the attachment between the negatively charged membrane surfaces of the bacterial cells and AgBiS2QDs was enhanced via the electrostatic interactions. The photodriven antibacterial activity of AgBiS2QDs was then investigated against both S. aureusand E. coli. The results revealed a significant reduction in bacterial survival. The killing effect was found to be independent of the AgBiS2QDs, and redox potentials controlled the photogenerated electrons that thermodynamically favored the formation of multiple reactive oxygen species (ROS). A possible phototriggered antibacterial mechanism was then proposed in which the AgBiS2QDs are anchored first to the bacterial surface and then induce breaking on its outer membrane by high local heat and ROS under single 808 nm NIR laser illumination to finally induce bacterial death.

Purpose: The paper aims to (1) explore the positive and negative sociocultural, economic, and environmental impacts on satisfaction, and behavioral intentions; and (2) examine the changes in relationships among event impacts, satisfaction and behavioral intentions of host city residents before and after a major sporting event. Design/methodology/approach: We used panel data to estimate how resident responses change over time. The data were collected three months before (Nbefore = 266) and three months after (Nafter = 266) the Nanjing Youth Olympic Games. Data were analyzed by confirmatory factor analysis (CFA), structural equation modeling (SEM) and invariance tests. Findings: A significant relationship exists between negative and positive perceived sociocultural, economic, and environmental impacts, satisfaction and behavioral intentions. In addition, findings suggest that the effect of the sociocultural impacts on satisfaction and of satisfaction on behavioral intentions strengthened after the event. The relationship between positive environmental impacts and satisfaction was reduced across the two points in time. Our results indicate that residents’ assessment regarding the sporting event partially changed over the whole six-month course of the study. Originality/value: This study differs from most recent research in that it examines the sociocultural, economic, and environmental event impacts in modeling residents’ satisfaction and testing the influence of negative event impacts on residents’ satisfaction and behavioral intentions. The current study contributes to the literature by emphasizing the changes that occur regarding the relationships among event impacts, satisfaction and behavioral intentions across the same respondents over time.

The design and synthesis of a novel π-conjugated fluorescent framework by external ligand-assisted C−H olefination of heterocycles with excellent regioselectivity and broad substrate scope are reported herein. These novel fluorescent materials could present full-color-tunable emissions with large Stokes shifts. Furthermore, the protocol provides an opportunity to rapidly screen novel organic single-molecule white-light materials with high fluorescence quantum yields. The robust organic and low-cost white light-emitting diodes could rapidly be fabricated using the white-light-emitting material. Experimental data and theoretical calculations indicate that in the white-light dual emission the relatively short wavelength from high-lying singlet state emission and the relatively long wavelength from low-lying singlet state emission. The anti-Kasha dual-emission systems will provide a foundation for the development and application of organic single-molecule white light materials, effectively promoting the development and innovation of luminescent materials. In addition, this method demonstrated its potential application in the synthesis of new near-infrared (NIR) fluorescence materials with large Stokes shifts based on the olefination of heterocycles.

A novel and selective cascade reaction of primary amines and alkynes for the synthesis of the corresponding secondary propargylamines is described. This protocol proceeds with a CuBr2/TBHP system through a process of oxidative deamination of primary amines to imine and alkynylation, featuring a wide scope of substrates with good functional-group tolerance and operational simplicity. Additionally, the use of two different primary amines could also work smoothly using this protocol.

The applications of graphene-based adsorbents were limited because of their complicated manufacturing technology and hi cost, thus it is very important to prepare new inexpensive and easily manufactured graphene-based adsorbents. Herein, novel GCP hydrogels with different graphene oxide (GO), chitosan (CS), and poly(vinyl alcohol) (PVA) ratios were facilely prepared through a method of freeze–thaw physical cross-linking, which was green and low-cost, and the structural characterization and adsorptive property of the optimum GCP1:2:4hydrogel toward Cd2+and Ni2+in wastewater was evaluated. It was found that the GCP1:2:4hydrogel had good mechanical strength and a special 3D interconnection porous structure. The isotherms of adsorption used the Langmuir model, and the kinetics of adsorption following the pseudo-second-order model were confirmed. Moreover, the adsorption property with respect to Cd2+and Ni2+in wastewater has been largely effected by the pH and was less influenced by the ionic strength and humic acid, and the GCP1:2:4hydrogel possessed excellent adsorptive and recyclable properties. These results demonstrated that the GCP1:2:4hydrogel could serve as a desirable adsorbent to get rid of heavy metal ions in sewage.

Inspired by nepenthes pitcher plants, Lubricant-Impregnated Surfaces (LISs) are surfaces with lubricant infused in the textures which form slippery interfaces. In this paper, we investigated slippery properties and the robustness of LISs with different micro-texture topologies (i.e., no textures, micro-pillar textures and micro hole textures), including original LISs and LISs rinsed by water. We measured the static contact angle, sliding angle and droplet motions on the LISs, using a contact angle instrument and a Particle Image Velocimetry (PIV) system. Similar contact angles and small sliding angles were observed on all original LISs, which indicated that an oil-layer existed on each LIS’s interface. After rinsed by water, the sliding angle increased obviously and the slip velocity decreased, which meant that the LISs slippery properties deteriorated in different degrees. Among all the LISs in our experiments, LIS with micro pillar textures has the best slippery performance and robustness before and after rinsed. We found that the LISs’ slippery properties were closely related to the states of the oil-layer on the interface, which were changed after rinsed. For the LIS with micro pillar textures, a thin layer of lubricant can sustain on the interface even after rinse, which made the droplet slide smoothly on the surface, with a lower sliding angle and a larger sliding velocity. This indicates that the proper micro-texture will enhance the slippery property and make it last longer.

A drug delivery system based on carboxymethyl cellulose-grafted graphene oxide loaded by methotrexate (MTX/CMC-GO) with pH-sensitive and controlled drug-release properties was developed in this work. CMC was grafted on graphene oxide by ethylenediamine through hydrothermal treatment. CMC serves as a pH-sensitive trigger, while CMC-GO serves as a drug-carrying vehicle due to the curved layer and large plain surface. Different amounts of drugs could be loaded into CMC-GO nanocarriers by control of the original amount of drug/carrier ratios. Additionally, low cytotoxicity against NIH-3T3 cells and low in vivotoxicity was observed. In vivotumor growth inhibition assays showed that MTX/CMC-GO demonstrated superior antitumor activity than free MTX against HT-29 cells. Moreover, prolonged survival time of mice was observed after MTX/CMC-GO administration. The MTX/CMC-GO drug delivery system has a great potential in colon cancer therapy.

Breast cancer progression, treatment resistance, and relapse are thought to originate from a small population of tumor cells, breast cancer stem cells (BCSCs). Identification of factors critical for BCSC function is therefore vital for the development of therapies. Here, we identify the arginine methyltransferase PRMT5 as a key in vitroand in vivoregulator of BCSC proliferation and self-renewal and establish FOXP1, a winged helix/forkhead transcription factor, as a critical effector of PRMT5-induced BCSC function. Mechanistically, PRMT5 recruitment to the FOXP1promoter facilitates H3R2me2s, SET1 recruitment, H3K4me3, and gene expression. Our findings are clinically significant, as PRMT5 depletion within established tumor xenografts or treatment of patient-derived BCSCs with a pre-clinical PRMT5 inhibitor substantially reduces BCSC numbers. Together, our findings highlight the importance of PRMT5 in BCSC maintenance and suggest that small-molecule inhibitors of PRMT5 or downstream targets could be an effective strategy eliminating this cancer-causing population.

The transcriptional network acting downstream of LIF, WNT and MAPK–ERK to stabilize mouse embryonic stem cells (ESCs) in their naive state has been extensively characterized. However, the upstream factors regulating these three signaling pathways remain largely uncharted. PR-domain-containing proteins (PRDMs) are zinc-finger sequence-specific chromatin factors that have essential roles in embryonic development and cell fate decisions. Here we characterize the transcriptional regulator PRDM15, which acts independently of PRDM14 to regulate the naive state of mouse ESCs. Mechanistically, PRDM15 modulates WNT and MAPK–ERK signaling by directly promoting the expression of Rspo1 (R-spondin1) and Spry1 (Sprouty1). Consistent with these findings, CRISPR–Cas9-mediated disruption of PRDM15-binding sites in the Rspo1 and Spry1 promoters recapitulates PRDM15 depletion, both in terms of local chromatin organization and the transcriptional modulation of these genes. Collectively, our findings uncover an essential role for PRDM15 as a chromatin factor that modulates the transcription of upstream regulators of WNT and MAPK–ERK signaling to safeguard naive pluripotency.

Solid-state electrolytes with high ionic conductivity, large electrochemical window, good mechanical properties, and easy processability are needed for high-energy solid-state lithium batteries. In this work, composite membranes consisting of lithium garnet (i.e. Li6.4La3Zr1.4Ta0.6O12, LLZTO) particles and Li-salt-free polyethylene oxides (PEOs) are produced as solid-state electrolytes. Li-ion-conducting particles in nano-scale are crucial for the enhancement of conductivity and the membranes containing ~40nm LLZTO particles exhibit conductivities nearly two orders of magnitude larger than those with the micro-scale ones, which is attributed to the difference in specific surface area related to the percolation effect. Compared to the conventional PEO doped with lithium salt, the insulating PEO in PEO:LLZTO membrane electrolyte is conducive to the suppression of lithium dendrite growth owing to prohibition of current flow. With PEO:LLZTO membrane electrolytes in conductivity of 2.1×10−4Scm−1at 30°C and 5.6×10−4Scm−1at 60°C, the solid-state LiFePO4/PEO:LLZTO/Li and LiFe0.15Mn0.85PO4/PEO:LLZTO/Li cells deliver energy densities of 345Whkg−1(662WhL−1) and 405Whkg−1(700WhL−1) (without the package weight or volume) with good rate capability and cycling performance. This study suggests that the conjunction of nano-scale Li-ion-conducting particles and an insulating polymer provides a promising solution to produce powerful solid-state electrolytes for high-performance solid-state lithium batteries.

This study aims at the mechanism of drag reduction in turbulent boundary layer (TBL) with superhydrophobic surface. Comparing the time-resolved particle image velocimetry (TRPIV) measurement results with that of hydrophilic surface, the drag reduction rate over a superhydrophobic surface is approximately 10%. To investigate the characteristics of coherent structure in a drag-reduced TBL with superhydrophobic surface, a modified multi-scale spatial locally-averaged structure function is proposed for detecting coherent structure. The conditional sampling and spatial phase-lock average methods are employed to obtain the topology of physical quantities like the velocity fluctuation, spanwise vorticity, and Reynolds stress during eject and sweep process. The results indicate that the suppression of coherent structure burst in the near-wall region is the key mechanism in reducing the skin friction drag for TBL over superhydrophobic surface.

There is growing recognition of cerebrovascular contributions to neurodegenerative diseases. In the walls of cerebral arteries, amyloid-beta (Aβ) accumulation is evident in a majority of aged people and patients with cerebral amyloid angiopathy. Here, we leverage human pluripotent stem cells to generate vascular smooth muscle cells (SMCs) from neural crest progenitors, recapitulating brain-vasculature-specific attributes of Aβ metabolism. We confirm that the lipoprotein receptor, LRP1, functions in our neural-crest-derived SMCs to mediate Aβ uptake and intracellular lysosomal degradation. Hypoxia significantly compromises the contribution of SMCs to Aβ clearance by suppressing LRP1 expression. This enabled us to develop an assay of Aβ uptake by using the neural crest-derived SMCs with hypoxia as a stress paradigm. We then tested several vascular protective compounds in a high-throughput format, demonstrating the value of stem-cell-based phenotypic screening for novel therapeutics and drug repurposing, aimed at alleviating amyloid burden.

Solid state reactive (SSR) sintering kinetics was observed for YAG ceramics. There were two densification stages in sintering process due to its reaction. After the first stage, samples began to expand, then, the second densification stage began. At a heating rate of 10 °C/min, the sample warped down and warped back to straight. The apparent activation energy of the first densification process was about 522 kJ/mol for the initial shrinkage of Al2O3and Y2O3mixed powder green-body, which increased in the following process due to the solid state reaction. In the second densification stage, synthesis reaction of YAG still worked. Green-bodies processed with higher heating rate got more shrinkage at the same temperature than lower heating rate green bodies. And its kinetic field diagram was abnormal, compared with that of other reported ceramics, such as Al2O3. It was found that the reaction of YAG provided positive effect to the sintering driving force. The apparent activation energy for densification of SSR YAG sintered in ArH5 atmosphere was 855 kJ/mol at temperature holding sintering. And the apparent activation energy for grain growth was 1053 kJ/mol.

Yttrium aluminum garnet (YAG) transparent ceramics were fabricated by sintering at oxygen atmosphere. Tetraethyl orthosilicate (TEOS) was added as the sintering additive to control the grain growth and densification. Pores were eliminated clearly at temperature lower than 1700 °C, while grain size was around 3 μm. The in-line transmittance was 80% at 1064 nm when samples were sintered at 1710 °C. The effect of TEOS was studied in oxygen atmosphere sintering for Nd:YAG transparent ceramics. At higher temperature like 1710 °C, the grain growth mechanism was solute drag, while at 1630 and 1550 °C the grain growth was controlled by liquid phase sintering mechanism. And 0.5 wt.% TEOS was the best adding content for Nd:YAG sintered in oxygen atmosphere.

Increasing numbers of proteins, nucleic acids and other molecular entities have been explored as therapeutic targets. A challenge in drug discovery is to decide which targets to pursue from an increasing pool of potential targets, given the fact that few innovative targets have made it to the approval list each year. Knowledge of existing drug targets (both approved and within clinical trials) is highly useful for facilitating target discovery, selection, exploration and tool development. The Therapeutic Target Database (TTD) has been developed and updated to provide information on 358 successful targets, 251 clinical trial targets and 1254 research targets in addition to 1511 approved drugs, 1118 clinical trials drugs and 2331 experimental drugs linked to their primary targets (3257 drugs with available structure data). This review briefly describes the TTD database and illustrates how its data can be explored for facilitating target and drug searches, the study of the mechanism of multi-target drugs and the development of in silicotarget discovery tools.

We report an easy catalyst-free method to prepare carbon microspheres via a hydrothermal carbonization process using starch solution as starting materials. SEM and TEM images show that the products consist of a large scale of monodisperse carbon microspheres with a size of about 2 μm. The size of the carbon microspheres can be easily controlled by regulating the concentration of the starch solution and the reaction temperature. Furthermore, the surface of the spheres is functionalized with hydroxyl and carboxyl groups, which make further surface modification unnecessary and facilitate immobilization of noble metal nanoparticles and fabrication of core−shell materials or hollow structures. Through SEM observation, the mechanism of the formation of carbon microspheres under hydrothermal conditions was suggested to be a direct dehydration polymerization and self-assemble fusion process. The present work provides a convenient yet effective method for large-scale synthesis of monodisperse carbon microspheres with high purity.

In the rainfed lowlands, rice (Oryza sativaL.) develops roots under anaerobic soil conditions with ponded water, prior to exposure to aerobic soil conditions and water stress. Constitutive root system development in anaerobic soil conditions has been reported to have a positive effect on subsequent expression of adaptive root traits and water extraction during water stress. We examined effects of phenotyping environment on identification of quantitative trait loci (QTLs) for constitutive root morphology traits using 220 doubled‐haploid lines (DHLs) from the cross of ‘CT9993‐5‐10‐1‐M’ (CT9993; japonica, upland adapted) × ‘IR62266‐42‐6‐2’ (IR62266; indica, lowland adapted) in four greenhouse experiments. Broad sense heritability (h2) was 75, 60, and 64% on average for shoot biomass, deep root morphology, and root thickness traits, respectively. Quantitative trait loci analysis identified 18 genomic regions associated with deep root morphology traits, but only three were identified consistently across experiments. Three out of a total of eight QTLs for root thickness traits were found in more than one experiment. The maximum genetic effects caused by a single QTL were increments of 0.05 g of deep root mass below a 30‐cm soil depth, 0.9% of deep root ratio, 1.6 cm of rooting depth, and 0.09 cm of root thickness, with phenotypic variation explained by a single QTL ranging from 6.8 to 51.8%. The results demonstrate the importance of phenotyping environment and suggest prospects for selection of QTLs for deep root morphology, root thickness, and vigorous seedling growth under anaerobic conditions to improve the constitutive root system of rainfed lowland rice. There was some consistency in QTL regions identified, despite the presence of QTL × environment interactions.

SummaryIt is well known that C4 crops have a lower water requirement than C3 crops. Reasons for the difference are not well understood. Therefore, hydraulic resistance of sorghum [Sorghum bicolor(L.) Moench] (C4) and sunflower (Helianthus annuusL.) (C3) was determined to see if it might be one explanation for the lower water use of crops with the C4 photosynthetic pathway. Plants were grown under greenhouse conditions in pots with soil, which was well watered (soil matric potential of ∼0 MPa) or allowed to dry (soil matric potential of −0.038 MPa and −0.065 MPa for sorghum and sunflower, respectively). Hydraulic resistance was calculated in two ways: (1) using the classic Ohm's law analogue, which assumes that the relation between flux (transpiration) and difference in water potentials of the soil and plant is linear and (2) using an equation that considers diurnal changes in leaf water content along with transpiration and difference in water potentials. Because change in leaf-water content during a day was small, hydraulic resistances calculated by the two methods resulted in similar values. Sorghum had a linear relationship between flux and difference in potentials (constant hydraulic resistance), but sunflower had a nonlinear one (variable hydraulic resistance). The hydraulic resistance of watered sunflower increased only slightly during a day and averaged about 40 MPa m2s mol−1, which was 3.5 times less than that of watered or water-stressed sorghum (-140 MPa m2s mol−1). The hydraulic resistance of water-stressed sunflower increased steeply during a day and by the end of the day it had a hydraulic resistance that approached that of sorghum.

Summary: Drought, extreme temperatures and high salinity are major limiting factors for plant growth and crop productivity. In their quest to feed the ever-increasing world population, agricultural scientists have to contend with these adverse environmental factors. If crops can be redesigned to better cope with abiotic stress, agricultural production can be increased dramatically. Recent advances in understanding crop abiotic stress resistance mechanisms and the advent of molecular genetic technology allow us to address these issues much more efficiently than in the past. This paper reviews the most significant achievements of the genetic engineering approach to improving plant abiotic stress resistance and discusses future prospects in transgenic research. Improved resistance to drought, salinity and extreme temperatures has been observed in transgenic plants that express/overexpress genes regulating osmolytes, specific proteins, antioxidants, ion homeostasis, transcription factors and membrane composition. Although the results are not always consistent, these studies collectively foretell a scenario where biotechnology will arm our future crops with new tactics to survive in hostile environments. Further experiments are needed to determine if the achieved increases in stress tolerance are applicable to agriculture.

Oxygenated biomass fuels have attracted significant attention due to their contributions in reducing environmental pollution and fossil fuel consumption. In view of stricter emission regulations, the use of these alternative fuels cannot fully meet the requirements, and it needs to be combined with an after-treatment system. In this article, polymethoxy dimethyl ether (PODE) and n-pentanol were blended with diesel (D100 (pure diesel)) at 15% and 20% by volume, respectively, referred to as D85P15, D80P20, D85A15, and D80A20, while the effects of the addition of two new oxygenated biomass fuels on the performance of diesel engine and diesel oxidation catalyst (DOC) and catalytic diesel particulate filter (CDPF) after-treatment system were experimentally investigated. Results show that the addition of oxygenated biomass fuels can improve combustion and reduce carbon monoxide (CO) and soot emissions. At heavy load conditions, when D80P20 was used, compared with D100 and D80A20, the conversion efficiency of CO emissions in DOC + CDPF system is always the highest, close to 100%. It shows that the addition of oxygenated biomass fuels can effectively improve the exhaust oxygen concentration. Besides, there is nearly no increase in CDPF pressure drop at each tested engine speed when D80P20 is used. This has greatly improved in CDPF performance.

IMPORTANCE: Methadone access may be uniquely vulnerable to disruption during COVID-19, and even short delays in access are associated with decreased medication initiation and increased illicit opioid use and overdose death. Relative to Canada, US methadone provision is more restricted and limited to specialized opioid treatment programs. OBJECTIVE: To compare timely access to methadone initiation in the US and Canada during COVID-19. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study was conducted from May to June 2020. Participating clinics provided methadone for opioid use disorder in 14 US states and territories and 3 Canadian provinces with the highest opioid overdose death rates. Statistical analysis was performed from July 2020 to January 2021. EXPOSURES: Nation and type of health insurance (US Medicaid and US self-pay vs Canadian provincial). MAIN OUTCOMES AND MEASURES: Proportion of clinics accepting new patients and days to first appointment. RESULTS: Among 268 of 298 US clinics contacted as a patient with Medicaid (90%), 271 of 301 US clinics contacted as a self-pay patient (90%), and 237 of 288 Canadian clinics contacted as a patient with provincial insurance (82%), new patients were accepted for methadone at 231 clinics (86%) during US Medicaid contacts, 230 clinics (85%) during US self-pay contacts, and at 210 clinics (89%) during Canadian contacts. Among clinics not accepting new patients, at least 44% of 27 clinics reported that the COVID-19 pandemic was the reason. The mean wait for first appointment was greater among US Medicaid contacts (3.5 days [95% CI, 2.9-4.2 days]) and US self-pay contacts (4.1 days [95% CI, 3.4-4.8 days]) than Canadian contacts (1.9 days [95% CI, 1.7-2.1 days]) (P?<?.001). Open-access model (walk-in hours for new patients without an appointment) utilization was reported by 57 Medicaid (30%), 57 self-pay (30%), and 115 Canadian (59%) contacts offering an appointment. CONCLUSIONS AND RELEVANCE: In this cross-sectional study of 2 nations, more than 1 in 10 methadone clinics were not accepting new patients. Canadian clinics offered more timely methadone access than US opioid treatment programs. These results suggest that the methadone access shortage was exacerbated by COVID-19 and that changes to the US opioid treatment program model are needed to improve the timeliness of access. Increased open-access model adoption may increase timely access.

Lipid peroxidation in sorghum and sunflower seedlings as affected by free-radical scavengers ascorbic acid, benzoic acid, and n-propyl gallate was studied. Roots of 17-day-old plants were immersed for 24 h in nutrient solution or nutrient solution containing either polyethylene glycol (PEG) or the scavengers. Compared with the nutrient solution treatment, PEG increased lipid peroxidation in sunflower, but had no effect in sorghum. Compared with the PEG-treated plants, ascorbic acid inhibited lipid peroxidation in both sunflower and sorghum, and benzoic acid had no effect, whereas n-propyl gallate inhibited lipid peroxidation in sorghum, but did not affect it in sunflower. However, levels of superoxide and hydrogen peroxide and activities of superoxide dismutase (SOD), ascorbate peroxidase (AP) and catalase (CAT) in the two species were not affected by the free-radical scavengers when compared with the PEG treatment. The PEG and the free-radical scavengers increased the ratios of SOD to CAT or AP in sunflower, but did not affect them in sorghum. These results suggest that sorghum is more resistant to oxidative stress than sunflower, and drought injury.induced by lipid peroxidation might be lessened by exogenous application of proper free-radical scavengers.

The heat‐balance method is widely used to monitor sap flow in stems of herbaceous plants. Measurements of sap flow made on monocotyledons, with scattered vascular bundles in their stems, may not be as accurate as measurements on dicotyledons, with annular vascular systems located next to the heater of the gauge. Therefore, we measured the accuracy of sap flow measurements made by the heat‐balance method for sunflower (Helianthus annuusL. ‘Hysun 354’), a dicotyledon with C3photosynthesis, and sorghum [Sorghum bicolor(L.) Moench, Funk's hybrid G‐522DR], a monocotyledon with C4photosynthesis. Plants were grown in pots with a commercial potting medium under greenhouse conditions. Measurements were made during a cycle when the plants were well watered, drought stressed, or rewatered. A potted plant was placed on a scale and sap flow (SF) values (units of g h−1) were compared with weight lost during the same period of time (WL, g h−1). Accuracy of the sap flow measurements was determined by calculating error, defined as (SF – WL)/WL. The gauge had good accuracy (error = 8.8%) only with watered sunflower, which had high flow rates (maximum rate = 64.7 g h−1). (This sap flow rate, nevertheless, is less than those for woody plants under field conditions, which are often >100 g h−1.) Sap flow rates in watered sorghum were less than those in watered sunflower (maximum sap flow rate = 18.9 g h−1), and error for watered sorghum was high (72.6%). The gauge had good accuracy when sap flow rates were 20 g h−1or more. Despite gauge errors, gauge measurements usually paralleled scale measurements and rapidly monitored changes in sap flow rate. The data suggest that sap flow rate is more important than stem anatomy in determining the accuracy of the gauge.

Ethylene production by drought-resistant and drought-sensitive genotypes of élite sorghum [Sorghum bicolor (L.) Moench] was measured to determine if genotypes varying in susceptibility to drought produced different amounts of ethylene. In addition, ethylene production by non-élite sorghums and landraces was analyzed. Leaves of 7-day-old seedlings were cut and weighed. Water-stressed leaves were allowed to lose 10% of their fresh weight before being placed in test tubes for analysis of ethylene evolution with a gas chromatograph. Well-watered leaves were not allowed to lose fresh weight. The four groups of sorghum (drought-resistant; drought-sensitive; non-élite; landraces) varied in ethylene production, but no one group always produced more (or less) ethylene compared to the other groups. In particular, the drought-sensitive sorghums did not consistently produce more (or less) ethylene than did the drought-resistant sorghums. Each genotype of sorghum produced more ethylene under water-stressed conditions than under well-watered conditions. But some genotypes produced more ethylene under well-watered conditions than others did under water-stressed conditions. The results showed that the variation of stress-ethylene production among genotypes was not related to drought sensitivity or drought resistance.