Clinically significant antibiotic resistance is one of the greatest challenges of the twenty‐first century. However, new antibacterial agents are currently being developed at a much slower pace than ...our growing need for such drugs. Given their diverse biological activities and clinical applications, many bioactive heterocyclic compounds containing a benzimidazole nucleus have been the focus of interest for many researchers. The benzimidazole nucleus is a structural isostere of naturally occurring nucleotides. This advantage allows benzimidazoles to readily interact with the various biopolymers found in living systems. In view of this situation, much attention has been given to the exploration of benzimidazole‐based antibacterial agents, leading to the discovery of many new chemical entities with intriguing profiles. In this minireview we summarize novel benzimidazole derivatives active against various bacterial strains. In particular, we outline the relationship between the structures of variously modified benzimidazoles and their antibacterial activity.
Can′t resist higher efficacy: Antibiotic resistance is one of the greatest challenges faced in the clinic. As a constituent of many bioactive heterocyclic compounds with diverse activities and clinical applications, the benzimidazole nucleus has generated widespread interest. Herein we summarize novel benzimidazole derivatives that are active against various bacterial strains and reveal the relationship between the structures of differently modified benzimidazoles and their antibacterial activities.
•CO2 absorption into aqueous glycerol/NaOH was measured in a wetted wall column.•Glyceroxide reacts with CO2 7 times faster than hydroxide.•In concentrated aqueous glycerol, glyceroxide is depleted ...at the interface.
The reaction kinetics of carbon dioxide and sodium hydroxide (nominally 0.1N and 0.3N) in aqueous glycerol were measured in a wetted wall column (WWC) at 20, 30, and 40°C. Glycerol was added at 0–89wt% to achieve a liquid viscosity (μL) of 0.89–65cP. Compared to pure aqueous alkaline solution, the absorption rate (kg′) initially increased by 30% and then decreased rapidly by 75% with increasing glycerol. Based on the measured kg′, a model was developed to calculate the overall reaction rate constant (kAlk), which resulted from the competing effects of CO2/NaOH (kOH-) and CO2/glyceroxide (kGlycerol-) reactions. The kGlycerol- was 6–7 times faster than kOH-. The non-monotonic trend of kg′ was the combined effect of kAlk increasing and diffusivity (DCO2) decreasing when glycerol increased. The effect of alkalinity depletion at the gas/liquid interface has been included in the kinetic model. The average depletion for 0.1N NaOH is 4% for water and 20% for 89wt% glycerol. Average depletion was less than 3% for 0.3N NaOH. The addition of 0.05N sodium carbonate has an insignificant effect on kg′.
Accurate prediction of global horizontal irradiance (GHI) is crucial for anticipating the volatility of solar power output. Under clear-sky conditions, aerosols play a significant role in influencing ...GHI, with different types of aerosols exhibiting distinct radiation effects. In this study, we employed the Planck mean aerosol optical depth (AOD) —Informer model to forecast future GHI, utilizing historical data of AOD, meteorological parameters, and GHI as input variables. Two data-fusion schemes were proposed, and the calculation results indicate that Scheme 1, organized in the order of Xianghe—Beijing—Shangdianzi (XBS) based on the day as a unit, demonstrates superior prediction performance. Additionally, the site information was blurred, allowing for the flexible selection of input and output lengths. The calculation results remained stable and reliable, suggesting that the inclusion of fuzzy site information does not degrade the prediction effect. Building upon this, we categorized aerosols into three types based on their time span and data volume. GHI predictions for different aerosol types revealed that the mean square error (0.145) for marine aerosols were significantly lower than those for the other types. The GHI predictions for continental aerosols were closest to the true values.
•LCC was estimated based on the UAV-based image analysis.•The response stability of vegetation index and LCC was analyzed under different coverage.•Different variable screening methods were used to ...optimize the spectral parameters.•The spatial distribution map of maize LCC was constructed to provide potentials for fertilization application.
Efficiently estimating chlorophyll content is important in monitoring the photosynthesis capacity and growth status of maize canopy in precision agriculture management. Vegetation index (VI) easily obtained by proximal remote sensing has been used as a non-destructive and high-throughput way in crop monitoring, especially in chlorophyll estimation. However, the estimated results of the field chlorophyll content by VIs always face challenges from soil background inhibition and estimation stability under the dynamic changes of vegetation biomass. Thus, an unmanned aerial vehicle (UAV)-based chlorophyll content estimation was conducted by evaluating VI responses under different crop coverages. An analysis was conducted on 36 VIs under different crop coverage conditions to explore their response differences and robustness for chlorophyll estimation. This work focused on the three kinds of VIs named simple vegetation index, modified vegetation index, and functional vegetation index. In 2020, at the experimental station of Dryland Farming Institute of Hebei Academy of Agriculture and Forestry Sciences, UAV carrying multispectral sensor was used to collect visible and near-infrared images of the canopy at the jointing stage of maize under six fertilization levels to obtain VIs. After the UAV fled, ground calibration and sample collection were performed simultaneously, and chlorophyll content was measured. For data processing, correlation coefficient method (CCM) and maximal information coefficient (MIC) were first used to analyze the correlation response characteristics of VIs and chlorophyll content under three different coverage levels. The results showed that when the level of canopy coverage was increased, the linear correlation between VIs and chlorophyll content was substantially reduced. The MIC response indicating linear and non-linear combination relationship was more robust. In addition, the VIs obtained by UAV had a significant linear correlation with maize canopy chlorophyll under low (0.05–0.35) and medium (0.35–0.48) coverage, but an obvious non-linear correlation under high (0.48–0.75) coverage. Chlorophyll-sensitive parameters were then screened based on methods of CCM, MIC, and random frog method (RFM), respectively. Partial least squares regression (PLS) and random forest (RF) algorithms were used to establish the maize canopy chlorophyll content detection models. The findings showed that when Green minus red vegetation index (GMR), Red light normalized value (NRI), Normalized difference red edge (NDRE), Modified simple ratio with red edge (MSRREG), Enhanced Vegetation Index (EVI), Normalized red green difference vegetation index (NDIg), Normalized red blue difference vegetation index (NDIb), Soil-adjusted vegetation index (SAVI), Optimized soil-adjusted vegetation index with red edge (OSAVIREG), Soil-atmospherically resistant vegetation index (SARVI) were selected based on RFM as the optimal spectral variables, the chlorophyll content detection model constructed based on PLS had the least numbers of characteristic variables and the best model accuracy. The training set R2 and RMSE were 0.753 and 2.089 mg/L, respectively, and the verification set R2 and RMSE were 0.682 and 2.361 mg/L, respectively. Field chlorophyll content and detection error distribution maps were also drawn and combined with the distribution of fertilization management to provide support for the UAV monitoring of crop growth in the field and variable fertilization management decisions.
Many individuals suffer from normal tension glaucoma (NTG) in China. This study utilized Markov models to evaluate the cost-utility of applying many medications and surgery for mild-stage NTG when ...disease progression occurred at a mild stage.
A 10-year decision-analytic Markov model was developed for the cost-utility analysis of treating mild-stage NTG with surgery and increased application of medication. We hypothesized that all 100,000 samples with a mean age of 64 were in mild stages of NTG. Transitional probabilities from the mild to moderate to severe stages and the basic parameters acquired from the CNTGS were calculated. Incremental cost-utility ratios (ICUR) were calculated for treating all patients with NTG by probabilistic sensitivity analysis (PSA) and Monte Carlo simulation. One-way sensitivity analysis were conducted by adjusting the progression rate, cost of medications or trabeculectomy, cost of follow-up, and surgical acceptance rate.
The ICUR of treating mild stage NTG with medication over 10 years was $12743.93 per quality-adjusted life years (QALYs). The ICUR for treating mild stage NTG patients with a 25% and 50% surgery rate with medication were $8798.93 and $4851.93 per QALYs, respectively. In this model, the cost-utility of treating NTG was sensitive to disease progression rate, surgical treatment rate, and medication costs.
According to the results of the cost-utility analysis, it was a reasonable and advantageous strategy to administer a lot of medication and surgery for NTG in the mild stages of the disease. In the model, the greater the probability of patients undergoing surgery, the strategy becomes more valuable.
Structural fatigue of NiTi shape memory alloys is a key issue that should be solved in order to promote their engineering applications and utilize their unique shape memory effect and ...super-elasticity more sufficiently. In this paper, the latest progresses made in experimental and theoretical analyses for the structural fatigue features of NiTi shape memory alloys are reviewed. First, macroscopic experimental observations to the pure mechanical and thermo-mechanical fatigue features of the alloys are summarized; then the state-of-arts in the mechanism analysis of fatigue rupture are addressed; further, advances in the construction of fatigue failure models are provided; finally, summary and future topics are outlined.
The reaction of non‐fluorinated silyl enol ether with alkyne is useful for the synthesis of β,γ‐unsaturated carbonyl compounds. However, most of the existing methods for realizing such organic ...transformation usually employ stoichiometric amounts of relatively expensive Lewis acids/metallic salts. Herein, an iron(III)‐catalyzed difluoroalkylation of aryl alkynes with difluoroenol silyl ether was developed. The reactions proceeded smoothly in the presence of a catalytic amount of iron(III) chloride, stoichiometric amounts of trimethylsilyl chloride, and 4 Å molecular sieves in dichloroethane (DCE) to afford the corresponding α‐alkenyl‐α,α‐difluoroketones in modest to good yields. Remarkably, among the various metallic salts screened, cheap and less‐toxic iron(III) salt was found to be the most efficient Lewis acid catalyst for the present reaction. In addition, in the absence of iron(III) chloride or trimethylsilyl chloride, either no reaction occurred or considerably reduced reaction performance was observed. Moreover, the use of Brønsted acid to replace iron(III) chloride as reaction catalyst failed to promote the reaction. The reaction could be scaled up and the obtained difluoroalkylated carbonyl compound serves as a versatile building block which could be subjected to late‐stage diversification to be converted into useful organic molecules containing CF2H and CF2CF2 moieties. Deuterated experiments showed that the proton in the generated alkene product should originate from trace amounts of water present in the reaction system.
The spread of the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has become a global health crisis. The binding affinity of SARS-CoV-2 (in ...particular the receptor binding domain, RBD) to its receptor angiotensin converting enzyme 2 (ACE2) and the antibodies is of great importance in understanding the infectivity of COVID-19 and evaluating the candidate therapeutic for COVID-19. We propose a new method based on molecular mechanics/Poisson–Boltzmann surface area (MM/PBSA) to accurately calculate the free energy of SARS-CoV-2 RBD binding to ACE2 and antibodies. The calculated binding free energy of SARS-CoV-2 RBD to ACE2 is –13.3 kcal/mol, and that of SARS-CoV RBD to ACE2 is –11.4 kcal/mol, which agree well with the experimental results of –11.3 kcal/mol and –10.1 kcal/mol, respectively. Moreover, we take two recently reported antibodies as examples, and calculate the free energy of antibodies binding to SARS-CoV-2 RBD, which is also consistent with the experimental findings. Further, within the framework of the modified MM/PBSA, we determine the key residues and the main driving forces for the SARS-CoV-2 RBD/CB6 interaction by the computational alanine scanning method. The present study offers a computationally efficient and numerically reliable method to evaluate the free energy of SARS-CoV-2 binding to other proteins, which may stimulate the development of the therapeutics against the COVID-19 disease in real applications.
The fluorinated decorations have recently been widely used in many biomedical applications. However, the potential mechanism of the fluorination effect on the cellular delivery of nanoparticles (NPs) ...still remains elusive. In this work, we systemically explore the penetration of a perfluoro-octanethiol-coated gold NP (PF-Au NP) and, for comparison, an octanethiol-coated gold NP (OT-Au NP) across lipid bilayers. We also investigated the effect of these two types of NPs on the properties of lipid bilayers. Our findings indicate that the lipid type and the surface tension of the lipid bilayer significantly impact the penetration capabilities of the fluorinated gold NP. By examining the distribution of ligands on the surface of the two types of NPs in water and during the penetration process, we unveil their distinct penetration characteristics. Specifically, the PF-Au NP exhibits amphiphobic behavior (both hydrophobic and lipophobic), while the OT-Au NP exhibits solely hydrophobic characteristics. Finally, we observe that the penetration capabilities can be increased by adjusting the degree of fluorination of the ligands on the NP surface. Overall, this study provides useful physical insights into the unique properties of the fluorinated decorations in NP permeation.
Although numerous studies have been devoted to the charge transfer through double-stranded DNA (dsDNA), one of the major problems that hinder their potential applications in molecular electronics is ...the fast deprotonation of guanine cation (G+•) to form a neutral radical that can cause the termination of hole transfer. It is thus of critical importance to explore other DNA structures, among which G-quadruplexes are an emerging topic. By nanosecond laser flash photolysis, we report here the direct observation and findings of the unusual deprotonation behavior (loss of amino proton N2–H instead of imino proton N1–H) and slower (1–2 orders of magnitude) deprotonation rate of G+• within G-quadruplexes, compared to the case in the free base dG or dsDNA. Four G-quadruplexes AG3(T2AG3)3, (G4T4G4)2, (TG4T)4, and G2T2G2TGTG2T2G2 (TBA) are measured systematically to examine the relationship of deprotonation with the hydrogen-bonding surroundings. Combined with in depth kinetic isotope experiments and pK a analysis, mechanistic insights have been further achieved, showing that it should be the non-hydrogen-bonded free proton to be released during deprotonation in G-quadruplexes, which is the N2–H exposed to solvent for G bases in G-quartets or the free N1–H for G base in the loop. The slower N2–H deprotonation rate can thus ensure less interruption of the hole transfer. The unique deprotonation features observed here for G-quadruplexes open possibilities for their interesting applications as molecular electronic devices, while the elucidated mechanisms can provide illuminations for the rational design of G-quadruplex structures toward such applications and enrich the fundamental understandings of DNA radical chemistry.
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