Oxidative MnO2 Template Assisted Electrochemical Fabrication of Graphene/Polypyrrole Supercapacitor Electrodes.

Improving the morphological structure of active materials is a reliable strategy for the fabrication of high-performance supercapacitor electrodes. In this study, we introduce a feasible approach to constructing the graphene/polypyrrole (PPy) composite film implanted onto the current collector through a two-step electrochemical deposition method utilizing MnO2 as an intermediary template. The reduced graphene oxide (rGO) hydrogel film is first hydrothermally grown on a carbon cloth (CC) substrate to obtain a porous rGO@CC electrode on which MnO2 is electrodeposited. Then the as-prepared rGO/MnO2@CC electrode is subjected to the electrochemical polymerization of pyrrole, with MnO2 acting as an oxidizing template to facilitate the oxidative polymerization of pyrrole, ultimately yielding an rGO/PPy composite film on CC. The PPy synthesized via this methodology exhibits a distinctive interconnected structure, resulting in superior electrochemical performance compared with the electrode with PPy directly electrodeposited on rGO@CC. The optimized electrode achieves an impressive specific capacitance of 583.6 F g-1 at 1 A g-1 and retains 83% of its capacitance at 20 A g-1, with a capacitance loss of only 9.5% after 5000 charge-discharge cycles. The corresponding all-solid-state supercapacitor could provide a high energy density of 22.5 Wh kg-1 and a power density of 4.6 kW kg-1, with a capacitance retention of 82.7% after 5000 charge-discharge cycles. Furthermore, the device also demonstrates good flexibility performance upon bending at 90 and 180°. This work presents an innovative method for the preparation of carbon material/conducting polymer electrodes with specific structural characteristics and superior performance.

One-Step Fabrication of Integrated Graphene/Polypyrrole/Carbon Cloth Films for Supercapacitor Electrodes.

The facile and cost-effective preparation of supercapacitor electrodes is significant for the application of this kind of electrochemical energy-storing module. In this work, we designed a feasible strategy to fabricate a binary active material onto a current collector in one step. A colloidal mixture of graphene oxide and pyrrole layered on a carbon cloth could undergo a redox reaction through a mild hydrothermal process to yield a reduced graphene oxide/polypyrrole hydrogel film anchored onto the carbon cloth. The integrated electrode with the porous graphene/polypyrrole active material could be directly utilized as a freestanding working electrode for electrochemical measurements and the assembly of supercapacitor devices. The as-prepared electrode could achieve a high capacitance of 1221 mF cm-2 at 1 mA cm-2 (531 F g-1) with satisfactory cycling stability. The constructed symmetric supercapacitor with two optimal electrodes could provide an energy density of 70.4 µWh cm-2 (15.3 Wh kg-1). This work offers a feasible pathway toward the integration of graphene/conducting polymer composites as electrochemical electrodes.

Causal roles of educational duration in bone mineral density and risk factors for osteoporosis: a Mendelian randomization study.

BACKGROUND: Educational duration might play a vital role in preventing the occurrence and development of osteoporosis(OP). PURPOSE: To assess the causal effect of educational duration on bone mineral density(BMD) and risk factors for OP by Mendelian randomization(MR) study. METHODS: The causal relationship was analyzed using data from genome-wide association study(GWAS). Inverse variance weighting (IVW) was used as the main analysis method. Horizontal pleiotropy was identified by MR-Egger intercept test, MR pleiotropy residual sum and outlier (MR-PRESSO) test. The leave-one-out method was used as a sensitivity analysis. RESULTS: The IVW results indicated that there was a positive causal relationship between educational duration and BMD (OR = 1.012, 95%CI:1.003-1.022), physical activity(PA) (OR = 1.156, 95%CI:1.032-1.295), calcium consumption (OR = 1.004, 95%CI:1.002-1.005), and coffee intake (OR = 1.019, 95%CI:1.014-1.024). There was a negative association between whole body fat mass (OR = 0.950, 95%CI:0.939-0.961), time for vigorous PA (OR = 0.955, 95%CI:0.939-0.972), sunbath (OR = 0.987, 95%CI:0.986-0.989), salt consumption (OR = 0.965, 95%CI:0.959-0.971), fizzy drink intake (OR = 0.985, 95%CI:0.978-0.992), smoking (OR = 0.969, 95%CI:0.964-0.975), and falling risk (OR = 0.976, 95%CI:0.965-0.987). There was no significant association between educational duration and lean mass, time for light-to-moderate PA, milk intake, and alcohol intake. Horizontal pleiotropy was absent in this study. The results were robust under sensitivity analyses. CONCLUSION: A longer educational duration was causally linked with increased BMD. No causal relationship had been found between educational duration and lean mass, time for light-to-moderate PA, milk intake, and alcohol consumption as risk factors for osteoporosis.

Mesoporous TiO2 layer suppresses ion accumulation in perovskite solar cells.

Ion accumulation in perovskite solar cells can be highly suppressed by a mesoporous TiO2 layer. This is evidenced by the decrease of the ion-related electrostatic potential with increasing the thickness of the mesoporous layer, accounted for by the electron population in the shallow trap states of the TiO2 nanocrystals.

Influence of the MACl additive on grain boundaries, trap-state properties, and charge dynamics in perovskite solar cells.

Grain boundary trap passivation in perovskite films has become one of the most effective strategies for suppressing the charge recombination and enhancing the photovoltaic performance of perovskite solar cells, whereas the relevant trap-state properties and the charge carrier dynamics need to be further clarified. In this work, the CH3NH3Cl (MACl) additive is introduced into the MAI:PbI2 precursor solution to obtain perovskite films comprising various grain sizes with distinct grain boundaries and trap-state properties. The influence of grain boundary traps passivated with the MACl additive on trap-state properties and charge carrier transport/recombination dynamics is systematically studied with time-resolved spectroscopic and transient photoelectric characterization. Specifically, the MACl amount determines the content of the PbI2 residual in the final perovskite, leading to photoluminescence quenching induced by charge transfer. The trap-state distribution result reveals that the deep-level traps at the grain boundaries as the main sources of charge recombination centers are dramatically passivated. Low-temperature photoluminescence spectroscopy distinguishes and compares the trap-state emission related to different perovskite phases. Transient photoelectric measurements including photovoltage decay and charge extraction further demonstrate that the boundary trap passivation can effectively promote charge transport and inhibit charge recombination in devices treated with the optimized MACl amount. As a result, the corresponding device possesses superior photovoltaic parameters to the control device. This work proposes a systematic understanding of the grain boundary trap passivation strategy and provides a new insight into the development of high-performance perovskite solar cells.

Identification of novel uracil derivatives incorporating benzoic acid moieties as highly potent Dipeptidyl Peptidase-IV inhibitors.

Dipeptidyl Peptidase-IV (DPP-4) is a validated therapeutic target for type 2 diabetes. Aiming to interact with both residues Try629 and Lys554 in S2' site, a series of novel uracil derivatives 1a-l and 2a-i incorporating benzoic acid moieties at the N3 position were designed and evaluated for their DPP-4 inhibitory activity. Structure-activity relationships (SAR) study led to the identification of the optimal compound 2b as a potent and selective DPP-4 inhibitor (IC50 = 1.7 nM). Docking study revealed the additional salt bridge formed between the carboxylic acid and primary amine of Lys554 has a key role in the enhancement of the activity. Furthermore, compound 2b exhibited no cytotoxicity in human hepatocyte LO2 cells up to 50 µM. Subsequent in vivo evaluations revealed that the ester of 2b robustly improves the glucose tolerance in normal mice. The overall results have shown that compound 2b has the potential to a safe and efficacious treatment for T2DM.

Charge carrier recombination dynamics in a bi-cationic perovskite solar cell.

The compositional engineering is of great importance to tune the electrical and optical properties of perovskite and improve the photovoltaic performance of perovskite solar cells. The exploration of the corresponding photoelectric conversion processes, especially the carrier recombination dynamics, will contribute to the optimization of the devices. In this work, perovskite with mixed methylammonium (MA) and formamidinium (FA) as organic cations, MA0.4FA0.6PbI3, is fabricated to study the influence of the bi-cation on the charge carrier recombination dynamics. X-ray diffraction analysis indicates the existence of the MAPbI3-FAPbI3 phase segregation in the bi-cationic perovskite crystal. The time-resolved photoluminescence dynamics presents a relatively fast carrier recombination process ascribed to the charge transfer from MAPbI3 to FAPbI3 in the bi-cationic perovskite film. The carrier recombination dynamics investigated by transient photovoltage measurements reveals a biphasic trap-assisted carrier recombination mechanism in the bi-cationic device, which involves carrier recombination in the MAPbI3 phase and FAPbI3 phase, respectively. The ultimate presentation of the carrier recombination process is closely related to the charge transfer between the two perovskite phases.

Characterization of the influences of morphology on the intrinsic properties of perovskite films by temperature-dependent and time-resolved spectroscopies.

Organic-inorganic halide perovskites have attracted enormous attention owing to their promising application in photovoltaic devices. The morphology of the perovskites is the key to driving the performance of perovskite devices, which necessitates a systematic study. In this work, two typical morphologies, i.e., flake and cube, of perovskite films are fabricated, and the temperature-dependent optical absorption and photoluminescence properties of the two types of perovskite film are systematically investigated. From the temperature-dependent spectra, both exciton and phase transition temperatures of the flake film are found to be about 10 K lower than those of the cube one. Meanwhile, the influences of the morphology on the exciton binding energy, optical phonon energy and polaron binding energy are quantitatively characterized. The exciton binding of the flake film is nearly three times smaller than that of the cube one, while the phonon coupling energy and the polaron binding energy of the former are about 5 meV and 2 meV larger than those of the latter. Furthermore, the results of photoluminescence lifetime and charge separation efficiency further reveal that the charge carrier kinetics in the two kinds of perovskite films is significantly different. The current study provides a theoretical framework to understand the fundamental physics of perovskites and to promote the design and enhancement of active materials for improved optoelectronic devices.

Adverse Effects of Excess Residual PbI2 on Photovoltaic Performance, Charge Separation, and Trap-State Properties in Mesoporous Structured Perovskite Solar Cells.

Organic-inorganic halide perovskite solar cells have rapidly come to prominence in the photovoltaic field. In this context, CH3 NH3 PbI3 , as the most widely adopted active layer, has been attracting great attention. Generally, in a CH3 NH3 PbI3 layer, unreacted PbI2 inevitably coexists with the perovskite crystals, especially following a two-step fabrication process. There appears to be a consensus that an appropriate amount of unreacted PbI2 is beneficial to the overall photovoltaic performance of a device, the only disadvantageous aspect of excess residual PbI2 being viewed as its insulating nature. However, the further development of such perovskite-based devices requires a deeper understanding of the role of residual PbI2 . In this work, PbI2 -enriched and PbI2 -controlled perovskite films, as two extreme cases, have been prepared by modulating the crystallinity of a pre-deposited PbI2 film. The effects of excess residual PbI2 have been elucidated on the basis of spectroscopic and optoelectronic studies. The initial charge separation, the trap-state density, and the trap-state distribution have all been found to be adversely affected in PbI2 -enriched devices, to the detriment of photovoltaic performance. This leads to a biphasic recombination process and accelerates the charge carrier recombination dynamics.

The Influence of Morphology and PbI2 on the Intrinsic Trap State Distribution in Perovskite Films Determined by Using Temperature-Dependent Fluorescence Spectroscopy.

Perovskite films with different particle sizes and PbI2 contents were prepared by using a controlled single or sequential method. By means of temperature-dependent fluorescence spectroscopy, the energetic distribution of intrinsic intragap trap states in perovskite was quantitatively determined, and the radiative charge recombinations through the band edge and via trap states were studied. Furthermore, a series of thermodynamic parameters, such as the demarcation energy between radiative and nonradiative recombination regions, detrapping activation energy, and characteristic temperature, were extracted based on which of the possible radiative and nonradiative recombination mechanisms were proposed. In addition, the correlation between the morphology of the perovskite films, the PbI2 content, and the energetic distribution of the trap states was investigated. Finally, we discuss the structure-function relationship of perovskite films prepared by different methods.

Power output and carrier dynamics studies of perovskite solar cells under working conditions.

Perovskite solar cells have emerged as promising photovoltaic systems with superb power conversion efficiency. For the practical application of perovskite devices, the greatest concerns are the power output density and the related dynamics under working conditions. In this study, the working conditions of planar and mesoscopic perovskite solar cells are simulated and the power output density evolutions with the working voltage are highlighted. The planar device exhibits higher capability of outputting power than the mesoscopic one. The transient photoelectric conversion dynamics are investigated under the open circuit, short circuit and working conditions. It is found that the power output and dynamic processes are correlated intrinsically, which suggests that the power output is the competitive result of the charge carrier recombination and transport. The present work offers a unique view to elucidating the relationship between the power output and the charge carrier dynamics for perovskite solar cells in a comprehensive manner, which would be beneficial to their future practical applications.

Mechanism of biphasic charge recombination and accumulation in TiO2 mesoporous structured perovskite solar cells.

Organic-inorganic halide perovskite solar cells are becoming the next big thing in the photovoltaic field owing to their rapidly developing photoelectric conversion performance. Herein, mesoporous structured perovskite devices with various perovskite grain sizes are fabricated by a sequential dropping method, and the charge recombination dynamics is investigated by transient optical-electric measurements. All devices exhibit an overall power conversion efficiency around 15%. More importantly, a biphasic trap-limited charge recombination process is proposed and interpreted by taking into account the specific charge accumulation mechanism in perovskite solar cells. At low Fermi levels, photo-generated electrons predominately populate in the perovskite phase, while at high Fermi levels, most electrons occupy traps in mesoporous TiO2. As a result, the dynamics of charge recombination is, respectively, dominated by the perovskite phase and mesoporous TiO2 in these two cases. The present work would give a new perspective on the charge recombination process in meso-structured perovskite solar cells.

Trap-limited charge recombination in intrinsic perovskite film and meso-superstructured perovskite solar cells and the passivation effect of the hole-transport material on trap states.

Charge recombination dynamics in intrinsic perovskite film and in meso-superstructured perovskite solar cells have been systematically studied, which are found to be mediated by the energetic distribution of intra-gap trap states as described by the trap-limited recombination theory. Besides, the passivation effect of the hole-transport material on trap states is discussed.

Characterization and distribution of poly(3-hexylthiophene) phases in an annealed blend film.

The characteristic absorption spectra of three kinds of phases, the isolated, ordered, and disordered phases, in a solvent-vapor annealed poly(3-hexylthiophene)/[6,6]-phenyl-C61 -butyric acid methyl ester (P3HT/PCBM) blend film were studied by means of spectroelectrochemistry (SEC) and time-resolved absorption spectroscopy (TAS). The results reveal that the content of three phases are 12 % isolated, 37 % ordered, and 51 % disordered for the annealed P3HT neat film, and 25 % isolated, 31 % ordered, and 44 % disordered for the annealed P3HT/PCBM blend film. The vertical distribution of the different phases in the blend film was studied by SEC, and the results show that the ordered and isolated phases are mainly distributed in the top and in the bottom of the annealed films, respectively, while the disordered phase is mainly distributed in the middle and the bottom of the films.

CAUSAL ROLES OF SERUM URIC ACID LEVELS AND GOUT IN SEPSIS: A MENDELIAN RANDOMIZATION STUDY.

ABSTRACT: Objective: Several epidemiological studies have identified a potential link between serum uric acid (UA), gout, and sepsis. The primary objective of this study is to delve deeper into this connection, investigating the causal effect of UA and gout on sepsis by applying Mendelian randomization (MR). Methods: The causal relationship was analyzed using data from Genome-Wide Association Study (GWAS). Inverse variance weighting (IVW) was used as the main analysis method. Three complementary methods were used for our MR analysis, which included the MR-Egger regression method, the weighted median method, the simple median method. Horizontal pleiotropy was identified by MR-Egger intercept test. Cochran's Q statistics were employed to assess the existence of instrument heterogeneity. The leave-one-out method was used as a sensitivity analysis. Results: The IVW results indicated that there was a positive causal relationship between UA and sepsis (critical care) (odds ratio [OR] = 0.24, 95% confidence interval [CI]: 0.04 to 0.43, P = 0.018, F = 4,291.20). There was no significant association between UA and sepsis (28-day death in critical care) (OR = 0.10, 95% CI = -0.29 to 0.50, P = 0.604). There was no significant association between gout and sepsis (critical care) (OR = 0.85, 95% CI = -4.87 to 6.57, P = 0.771), and sepsis (28-day death in critical care) (OR = -6.30, 95% CI = -17.41 to 4.81, P = 0.267). Horizontal pleiotropy was absent in this study. The results were robust under all sensitivity analyses. Conclusion: The study revealed that elevated UA levels were causally linked with sepsis (critical care). No causal relationship had been found between UA and sepsis (28-day death in critical care), as well as between gout and sepsis.

The pH-controlled morphology transition of polyaniline from nanofibers to nanospheres.

To explore the dependences of polyaniline (PANI) morphology on the oxidant and the initial pH value (referred to as 'pH-initial') of the reaction system, a series of oxidative polymerization experiments on aniline using chloroaurate acid (HAuCl4) as the oxidant are carried out in aqueous solutions with different values of pH-initial. The smooth morphology transition of PANI nanostructures from nanofibers to solid and hollow nanospheres can be controlled by simply changing pH-initial for the reaction solution using HAuCl4 as the oxidant. In aqueous solutions with different values of pH-initial, the anilinium ions and neutral aniline molecules coexist in different proportions, leading to different PANI nanostructures under different nucleation mechanisms. In strongly acidic media (pH-initial < 2), the homogeneous nucleation of PANI will result in PANI nanofibers. When pH-initial is raised to 2 or above, the heterogeneous nucleation will lead to solid or hollow PANI nanospheres. The solid PANI nanospheres are obtained in mildly acidic media (pH-initial=2-4) and the diameter decreases as the initial pH value of the reaction solution increases from 2 to 4. However, in weakly acidic and neutral media (pH-initial=5-7), hollow PANI nanospheres are formed and the diameter increases with the increase of pH-initial for the solution from 5 to 7.

[The infection status and epidemic rule of new bunia virus in the livestock and poultry in hilly area of Jiaodong peninsula].

OBJECTIVE: To understand the infection status and epidemic rule of new bunia virus in the livestock and poultry which are closely related with humans such as sheep, cattle, dogs, pigs and chicken in the hilly area of Jiaodong peninsula in Shandong province. METHODS: Penglai and Laizhou in the hilly area of Jiaodong peninsula in Shandong province where severe fever with thrombocytopenia syndrome cases occurred in 2010 were selected as experimental sites. During April to November in 2011, serum specimens of the sheep, cattle, dogs, pigs and chicken with ticks in endemic area were randomly collected by random number table.5 ml venous blood was collected in each livestocks or poultries and there were total 3576 samples.New bunia virus antibody in different species of livestocks or poultries serum was continuously detected using double antigen sandwich enzyme-linked immunosorbent assay, and the infection rates of new bunia virus between different species of livestocks or poultries and between Penglai and Laizhou were analyzed using chi-square test. RESULTS: Test results in 3576 samples of livestocks or poultries serum specimen showed that the infection rate was as high as 63% (636/1013) in sheep, 53% (444/841)in cattle, 46% (242/530) in chicken, 29% (104/362)in the dogs, and 1% (12/830) in pigs. There were significant differences of new bunia virus infection among different species (χ(2) = 815.26, P < 0.05).In Penglai, the infection rate was as high as 71% (400/563) in sheep, 57% (232/409)in cattle, 35% (93/266) in chicken, 44% (796/1819)in total, while in Laizhou, the infection rate was 53% (236/450)in sheep, 49% (212/432)in cattle, 56% (149/264)in chicken, 36% (642/1757)in total, their difference was statistically significant(χ(2) values were 37.04, 4.93, 24.63, 19.38, all P values were < 0.05).Infection rates of dogs and pigs showed no obvious fluctuation.However, there were two peaks of infection in sheep in summer and autumn, the infection rate was as high as 62% (68/110) in June and 86% (204/236) in November;There were two peaks of infection in cattle in spring and autumn, the infection rate was as high as 56% (53/94) in April and 73% (116/159) in November; there was only one peak of infection in chicken, the infection rate was as high as 65% (55/85) in September. CONCLUSION: The infection rate is higher in sheep, cattle, chickens and dogs in the hilly area of Jiaodong peninsula. The peak season is spring, summer and autumn.

Synthesis and biological evaluation of capsaicin analogues as antioxidant and neuroprotective agents.

Capsaicin and its analogues 3a-3q were designed and synthesized as potential new antioxidant and neuroprotective agents. Many analogues exhibited good antioxidant effects, and some showed more potent free radical scavenging activities than the positive drug quercetin (IC50 = 8.70 ± 1.75 µM for DPPH assay and 13.85 ± 2.87 µM for ABTS assay, respectively). The phenolic hydroxyl of capsaicin analogues was critical in determining antioxidant activity. Among these compounds, 3k displayed the most potent antioxidant activity. Cell vitality tests revealed that the representative compound 3k was good at protecting cells from H2O2-induced oxidative damage at low concentrations (cell viability increased to 90.0 ± 5.5% at 10 µM). In addition, the study demonstrated that 3k could reduce intracellular ROS accumulation and increase GSH levels to prevent H2O2-induced oxidative stress in SY5Y cells. In the mitochondrial membrane potential assay, 3k significantly increased the MMP level of SY5Y cells treated with H2O2 and played an anti-neuronal cell death role. These results provide a promising strategy to develop novel capsaicin analogues as potential antioxidant and neuroprotective agents.

Does prior exposure to immune checkpoint inhibitors treatment affect incidence and mortality of COVID-19 among the cancer patients: The systematic review and meta-analysis.

BACKGROUND: Immune checkpoint inhibitors (ICIs) treatment among cancer patients has been shown to have antiviral effects by reactivating exhausted T cells. However, they could also trigger inflammatory storm. Therefore, prior exposure to ICIs may influence the risk of SARS-CoV2 infection and subsequent mortality. Recent results from studies of ICIs treatment on incidence and mortality of COVID-19 are controversial. MATERIALS AND METHODS: We searched databases PubMed, Embase, ISI of Knowledge, Cochrane Central Register of Controlled Trials (CENTRAL), as well as pre-print databases (MedRxiv and BioRxiv) for retrospective and prospective studies comparing ICIs versus other antitumor treatments in cancer patients in the area of COVID-19 pandemic. The primary outcome was the incidence of COVID-19. The secondary outcomes were mortality of COVID-19. RESULTS: Twenty-three studies with a total of 117,735 patients were selected. Compared with other antitumor treatments, prior exposure to ICIs had not an increased risk of incidence [Odds ratio (OR), 0.84; 95% confidence interval (CI), 0.60-1.18; P = 0.32] and mortality (OR, 1.22; 95% CI, 0.91-1.62; P = 0.18) of COVID-19 infectioin. Our subgroup and meta-regression analyses indicated that prior exposure to ICIs may reduce the incidence of COVID-19 in metastatic cancer patients. CONCLUSIONS: There was no significant difference on incidence and mortality of COVID-19 between prior exposure to ICIs with other anti-tumor treatments. ICIs may reduce infection susceptibility of COVID-19 in metastatic cancer patients.

[Analysis of related factors of carbapenem resistant Klebsiella pneumoniae infection in patients with artificial airway].

OBJECTIVE: To analyze the clinical characteristics and related influencing factors of carbapenem resistant Klebsiella pneumoniae (CRKP) in patients with artificial airway and mechanical ventilation in intensive care unit (ICU), and provide theoretical basis for clinical prevention of Klebsiella pneumoniae infection. METHODS: The clinical data of patients with pulmonary infection of Klebsiella pneumoniae in ICU of Beijing Shijitan Hospital Affiliated to Capital Medical University from January 2016 to December 2019 were collected. Compared CRKP pneumonia patients (study group) with carbapenem antibiotic sensitive Klebsiella pneumoniae (CSKP) pneumonia patients (control group), the clinical characteristics [gender, age, acute physiology and chronic health evaluation II (APACHE II), duration of mechanical ventilation, proportion of patients with mechanical ventilation > 10 days, use of antibiotics before detection of Klebsiella pneumoniae, white blood cell count (WBC), C-reactive protein (CRP), procalcitonin (PCT), albumin, bedridden for more than 1 month before admission, 28-day mortality] were analyzed. The drug resistance rates of Klebsiella pneumoniae in both groups and difference of drug resistance rate of Klebsiella pneumoniae to different antibiotics from 2016 to 2019 were compared. The risk factors of CRKP infection were analyzed by multivariate Logistic regression, and the related drug resistance genes were detected. RESULTS: Compared with the control group, the study group was older [years old: 81.5 (72.0, 86.0) vs. 78.0 (71.0, 80.5)], APACHE II [point: 25.00 (20.00, 34.00) vs. 19.00 (14.00, 23.25)] and proportion of patients with mechanical ventilation > 10 days [63.2% (182/288) vs. 12.8% (10/78)], the use of ß-lactamase inhibitor antibiotics before detection of Klebsiella pneumoniae [75.69% (218/288) vs. 30.77% (24/78)], the use of carbapenems [79.86% (230/288) vs. 41.03% (32/78)], the use of more than two kinds of antibiotics [80.90% (233/288) vs. 29.49% (23/78)], proportion of patients staying in bed for more than 1 month before admission [40.97% (118/288) vs. 11.54% (9/78)] and WBC [×109/L: 9.72 (6.41, 14.69) vs. 7.57 (5.84, 12.61)], CRP [mg/L: 74.45 (36.30, 158.88) vs. 39.22 (13.68, 92.51)], PCT [µg/L: 3.87 (0.82, 19.24) vs. 0.51 (0.25, 5.71)], 28-day mortality [21.5% (62/288) vs. 10.3% (8/78)] were higher, albumin [g/L: 24.1 (18.3, 28.6) vs. 30.1 (23.8, 35.1)] was lower, duration of mechanical ventilation [days: 16.5 (9.0, 19.0) vs. 7.0 (5.0, 10.0)] was longer, the proportion of patients with chronic obstructive pulmonary disease [COPD: 35.76% (103/288) vs. 11.54% (9/78)], malignant tumor [18.06% (52/288) vs. 5.13% (4/78)], renal failure [31.94% (92/288) vs. 11.54% (9/78)], shock [51.74% (149/288) vs. 19.23% (15/78)] were higher, and the differences were statistically significant (all P < 0.05). The drug resistance rates of Klebsiella pneumoniae to aztreonam, piperacillin/tazobactam, imipenem and ciprofloxacin were statistically significant (all P < 0.05); the drug resistance rates of Klebsiella pneumoniae to aztreonam and piperacillin/tazobactam were the highest in 2019 (88.17% and 86.02%, respectively), and the lowest in 2016 (70.65% and 57.61%, respectively). The drug resistance rate to imipenem was the highest in 2018 (86.32%), the lowest in 2016 (59.78%); the resistance rate to ciprofloxacin was the highest in 2016 (76.09%), and the lowest in 2018 (53.68%). The resistance rates of ceftetan, amikacin, piperacillin/tazobactam, ceftazidime, ceftriaxone and gentamicin in the study group were significantly higher than those in the control group (82.99% vs. 62.82%, 49.31% vs. 17.95%, 75.69% vs. 60.26%, 81.25% vs. 64.10%, 80.21% vs. 58.97%, 91.32% vs. 60.26%, all P < 0.05). Logistic regression analysis showed that COPD, severe hypoproteinemia, mechanical ventilation time > 10 days and the use of carbapenem antibiotics before detection of Klebsiella pneumoniae were independent risk factors of CRKP infection. Gene detection showed that there were TEM, KPC, AmpC, AAC(3)-II, ant(3")-I, qnrS and other drug resistance genes in CRKP. The detection rate of TEM was the highest (74.00%), and qnrA was the lowest (6.67%). CONCLUSIONS: The occurrence of CRKP in ICU patients with artificial airway and mechanical ventilation is related to many factors. It is necessary to shorten the mechanical ventilation time, avoid the nonstandard use of carbapenem antibiotics, and improve the serum albumin level, so as to reduce the incidence of CRKP pneumonia and improve the prognosis of patients.