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1.
Carbohydr Polym ; 250: 116873, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33049821

RESUMO

Porous Al-doped ZnO/cellulose (AZOC) composites were successfully fabricated via a chemical deposition method. The micro-/nano cellulose fibers (MNCF) with tunable sizes were prepared by grinding treatment, and used as substrates for synthesizing ZnO/MNCF and AZOC composites. With the increasing of grinding treatment times, the average fiber diameter of MNCF decreased, that of MNCF-10, MNCF-20 and MNCF-30 were 100 nm, 58 nm and 31 nm, which was observed by scanning electron microscopy (SEM). The fiber sizes of MNCF played an important role in the sizes of ZnO and Al-doped ZnO, also pore structures and photocatalytic properties of ZnO/MNCF and AZOC composites. The sizes of ZnO (or Al-doped ZnO) nanoparticles decreased with the decreasing of MNCF diameter. The AZOC composite with average fiber diameter of 31 nm (under grinding treatment of 30 times) exhibited the highest porosity (94.6 %). The obtained ZnO/MNCF and AZOC composites were further analyzed using X-ray diffraction (XRD), Raman spectrometry, X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy (DRS). Due to the introduction of Al element dopant, the AZOC showed a much better photocatalytic efficiency (89.9 %) than pure ZnO powders (22.5 %) and ZnO/MNCF composites (53.3 %). Moreover, the AZOC composite can be recycled more than 10 times with negligible photocatalytic efficiency loss.

2.
Pharm Biol ; 58(1): 838-844, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32878529

RESUMO

CONTEXT: Cyclocarya paliurus (CP) (Batal.) Iljinsk (Cyclocaryaceae), a plant native to China, is the sole species in the genus Cyclocarya. Its leaves have been widely used as a remedy for hyperlipidaemia in traditional folk medicine. However, the mechanism underlying CP-induced lipolysis, especially in the liver, has not been entirely elucidated. OBJECTIVE: This study investigates the effect of CP ethanol extract (CPE) on hepatic steatosis and the underlying molecular mechanisms involved. MATERIALS AND METHODS: The effect of CPE at concentrations of 0, 6.25, 12.5, 25, 50, and 100 µg/mL on the viability of HepG2 cells was examined using the cell counting kit-8 (CCK-8) assay after incubation for 24 h. CPE-induced changes in intracellular lipid content were assessed by measuring the absorbance of oil red O staining at 520 nm, and the possible underlying mechanisms were further studied using quantitative reverse transcription polymerase chain reaction (RT-qPCR) analysis, western blotting, immunofluorescence studies and transmission electron microscopy. RESULTS: The half-maximal inhibitory concentration (IC50) of CPE in HepG2 cells was 97.27 µg/mL. Treatment with 50 µg/mL CPE increased lipid clearance, which was associated with increased autophagy in HepG2 cells. CPE-induced autophagy involved downregulation of phosphorylation level of mammalian target of rapamycin (0.87 ± 0.08 vs. 1.31 ± 0.10). Fluorescent double staining and electron microscopy images showed lipid deposits within autolysosomes, thereby confirming the abovementioned findings. DISCUSSION AND CONCLUSIONS: CPE can induce hepatic fat clearance through the autophagy-lysosome pathway known as lipophagy. CPE has potential as a functional food.

3.
Artigo em Inglês | MEDLINE | ID: mdl-32976637

RESUMO

The coronavirus disease 2019 (COVID-19) pandemic presents an unprecedented threat to global public health. The spread of the severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) infections in a global scale has affected more than 30.6 million people suffering the COVID-19, resulting in more than 955,000 deaths globally as of the 20 September 2020. The current lack of specific and effective therapies for the COVID-19, and the continuous spread of coronavirus SARS-CoV-2 across many parts of the world, represent one of the major challenges in controlling the disease severity, keeping to pose a huge threat to the global health.

4.
Biomaterials ; 262: 120336, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32920428

RESUMO

Hydration lubrication is the key responsible for the exceptionally low boundary friction between biosurfaces. However, it is a challenge to settle a hydration layer on a polymer surface via a noncovalent manner. Herein, we develop a highly lubricated coating absorbed onto the polymer surface via intermolecular association of hyaluronic acid (HA)-based micelles. A poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymer (Pluronic, F127) is recruited to complex with HA and further self-assembled to form a thick micelle layer. High water-retaining capacity of the HA/F127 coating enables the decorated surface with excellent hydrophilicity and boundary lubrication, where the coefficient of friction in aqueous media is reduced by 60% compared with the bare polymer surface. The HA/F127 coating suppresses nonspecific protein adsorption and exhibits good biocompatibility. More remarkably, an in vivo cynomolgus monkey model, demonstrates the utility of the HA/F127 coating in alleviating or preventing complications of endotracheal intubation, such as foreign irritation, airway mucosal damage, and inflammatory response. This cost-effective and scalable approach is suitable to manufacture interventional devices especially disposable medical devices with highly lubricated surface.

5.
J Radiat Res ; 2020 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-32823282

RESUMO

To design a new breast vacuum bag to reduce global and local setup errors in post-mastectomy radiation therapy (PMRT). A total of 24 PMRT patients were immobilized with an old vacuum bag and 26 PMRT patients were immobilized with a new vacuum bag. The registration results were analysed using four regions of interest (ROI): the global ROI [including the whole region of the planning target volume (PTV), GROI], the supraclavicular area (SROI), the ipsilateral chest wall region (CROI) and the ipsilateral arm region (AROI). The global and local setup errors of the two groups were compared. The global setup errors of the new vacuum group were significantly smaller than those in the old vacuum group with the exception of yaw axes (P < 0.05). The systematic error (Σ) and random error (σ) ranged from 1.21 to 2.13 mm. In the new vacuum group, the local setup errors in the medial-lateral (ML) direction and roll axes for CROI (the Σ and σ ranged from 0.65 to 1.35 mm), and the local setup errors in ML and superior-inferior (SI) directions for SROI were significantly smaller than those in the old vacuum group. The total required PTV margins for the chest wall in ML, SI, and anterior-posterior (AP) were 4.40, 3.12 and 3.77 mm respectively. The new vacuum bag can significantly reduce the global setup errors and local setup errors in PMRT. The respiratory motion of the chest wall was negligible, and the 5 mm PTV margin could cover the local setup errors in PMRT using the new vacuum bag with cone beam CT (CBCT) correction.

6.
Food Funct ; 11(8): 7245-7254, 2020 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-32766662

RESUMO

Antibacterial peptide CM4 (ABP-CM4) is a small cationic peptide with broad-spectrum activities against bacteria, fungi and tumor cells and may possibly be used as an antimicrobial agent. In this study, a C-terminal amidated antibacterial peptide ABP-CM4 (ABP-CM4N) with the strongest antibacterial activity was obtained through screening the antibacterial activities of ABP-CM4 with different modifications. The minimal inhibitory concentration of ABP-CM4N was 8 µM against P. aeruginosa (ATCC 27853) which was lower than that of ABP-CM4 (16 µM). The strengthened antimicrobial activity of ABP-CM4N may be associated with the increased membrane binding capacity, being two times that of ABP-CM4 (p < 0.001). The antibacterial mechanism of ABP-CM4N to Pseudomonas aeruginosa was examined by means of cell membrane integrity analysiss, the intracellular ultrastructure change observation and E. coli genomic DNA binding assay. It was found that ABP-CM4N had the same antimicrobial mechanism as ABP-CM4, and the aim of the antimicrobial mechanism was mainly to destroy the cell membrane which caused nucleic acid or protein leakage, and secondly to interact with E. coli genomic DNA after penetrating the cell membrane. Furthermore, in vitro ABP-CM4N showed a better bacteriostatic activity in meats, with the treated samples showing two to three times less positive colonies than ABP-CM4.

7.
Clin Lab ; 66(8)2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32776732

RESUMO

BACKGROUND: Customer satisfaction is one of quality indicators which can be used to identify quality defects in the total process and remind clinical laboratories to take measures to improve the process. This study mainly reviewed and analyzed the general situation through a customer satisfaction survey in clinical laboratories in China and described the overall customer satisfaction of outpatients and inpatients. METHODS: Surveys in this study could be divided into two stages. The first stage was to investigate the general situation through a customer satisfaction survey in Chinese clinical laboratories. In the second stage, clinical laboratories carried out nationwide surveys on the satisfaction of outpatients and inpatients. Chi-square test and logistic regression analysis were applied to determine the relationship between the general characteristics of patients and patient satisfaction. RESULTS: The recovery rate in the first stage was 34.54%. In the second stage, we received 12,919 outpatient questionnaires and 11,818 inpatient questionnaires. Outpatients and inpatients had a common trend: satisfaction rates increased with age and decreased with frequency of visit. Patients who possessed a bachelor degree or above had a higher satisfaction rate than those who had only received a high school education or below. CONCLUSIONS: There was a high level of patient satisfaction with clinical laboratory services, but aspects of dissatisfaction still existed, which provided opportunities for clinical laboratories in China to improve their service quality.

8.
Ann Surg ; 2020 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-32657939

RESUMO

OBJECTIVE: The International Patterns of Opioid Prescribing study compares postoperative opioid prescribing patterns in the United States (US) versus the rest of the world. SUMMARY OF BACKGROUND DATA: The US is in the middle of an unprecedented opioid epidemic. Diversion of unused opioids contributes to the opioid epidemic. METHODS: Patients ≥16 years old undergoing appendectomy, cholecystectomy, or inguinal hernia repair in 14 hospitals from 8 countries during a 6-month period were included. Medical records were systematically reviewed to identify: (1) preoperative, intraoperative, and postoperative characteristics, (2) opioid intake within 3 months preoperatively, (3) opioid prescription upon discharge, and (4) opioid refills within 3 months postoperatively. The median/range and mean/standard deviation of number of pills and OME were compared between the US and non-US patients. RESULTS: A total of 4690 patients were included. The mean age was 49 years, 47% were female, and 4% had opioid use history. Ninety-one percent of US patients were prescribed opioids, compared to 5% of non-US patients (P < 0.001). The median number of opioid pills and OME prescribed were 20 (0-135) and 150 (0-1680) mg for US versus 0 (0-50) and 0 (0-600) mg for non-US patients, respectively (both P < 0.001). The mean number of opioid pills and OME prescribed were 23.1 ±â€Š13.9 in US and 183.5 ±â€Š133.7 mg versus 0.8 ±â€Š3.9 and 4.6 ±â€Š27.7 mg in non-US patients, respectively (both P < 0.001). Opioid refill rates were 4.7% for US and 1.0% non-US patients (P < 0.001). CONCLUSIONS: US physicians prescribe alarmingly high amounts of opioid medications postoperatively. Further efforts should focus on limiting opioid prescribing and emphasize non-opioid alternatives in the US.

9.
Int J Surg Case Rep ; 73: 203-206, 2020 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-32693236

RESUMO

INTRODUCTION: Dislocation after bipolar hip hemiarthroplasty is an uncommon complication. Although closed manoeuvre reduction under general anaesthesia is a common and effective method for dislocation of the hemiarthroplasty. However, closed reduction leads to preprosthesis fracture of femoral and loosening of femoral prosthesis is a rare situation, which requires incision reduction and a revision hemiarthroplasty. PRESENTATION OF CASE: A 80-year-old female had cementless bipolar hip hemiarthroplasty due to a right femoral neck fracture. At the 11 days of postoperation, the patient had a dislocation of the hemiarthroplasty when squatting. The patient had preprosthesis fracture and loosening of the prosthesis during closed reduction. Eventually, the patient had an open reduction and femoral stem revision. There was no re-dislocation and no re-fracture at one-year follow-up. DISCUSSION: Closed manoeuvre reduction is a common and effective method for dislocation of the hemiarthroplasty. But if not done properly, it may lead to preprosthesis fracture of femoral and loosening of the femoral prosthesis. Preprosthesis fracture of femoral and loosening of femoral prosthesis is a complex complication. This condition requires operative treatment. A personalized surgical plan and proper techniques should be done before the operation. CONCLUSION: Closed reduction should be performed gently to avoid preprosthesis fracture and loosening of the prosthesis. If this happens, a high-resolution CT examination should be performed immediately to evaluate the fracture and the rotation of the prosthesis. In the case of dislocation after bipolar hip hemiarthroplasty in patients with Alzheimer's disease, we hypothesize that early wearing braces to limit squat might help prevent this condition.

10.
Artigo em Inglês | MEDLINE | ID: mdl-32490656

RESUMO

Developing novel bifunctional electrocatalysts with advanced oxygen electrocatalytic activity is pivotal for next-generation energy-storage devices. Herein, we present an ultrathin oxygen doped FePSe3 (FePSe3-O) nanosheets by the Ar/O2 plasma treatment with remarkable surface atom reorganization. Such surface atom reorganization generates multiple crystalline-amorphous interfaces that benefit the kinetics of oxygen evolution reaction, achieving a low overpotential of only 261 mV at 10 mA cm2 with a small Tafel slope of 41.13 mV dec1. Density functional theory calculation indicates that the oxygen doping can also modulate the electrical states at the Fermi level with a decreased band gap responsible for the enhanced electrocatalytic performance. Such unique FePSe3-O nanosheets can be further fabricated as the air cathode in rechargeable liquid zinc-air batteries (ZABs), which deliver a high open circuit potential of 1.47 V, a small charge-discharge voltage gap of 0.80 V, and good cycling stability for more than 800 circles. As a proof of concept, the flexible solid-state ZABs assembled with FePSe3-O nanosheets cathode also display a favorable charge-discharge performance, durable stability, and good bendability. This work sheds new insight into the rational design of defect-rich ternary thiophosphate nanosheets by plasma treatment towards enhanced oxygen electrocatalysts in metal-air batteries.

11.
Clin Lab ; 66(6)2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32538063

RESUMO

BACKGROUND: Community acquired pneumonia remains a leading infectious cause of hospitalization with substantial morbidity and mortality in China. At present, the role of atypical pathogens in CAP arouses peoples' concern. Previous studies indicated that MP was the dominant pathogen of CAP, but the associated factors of MP infection were rarely reported. METHODS: We retrospectively investigated the distribution of atypical pathogens related with CAP and compared their differences among various populations. Furthermore, we accessed the associated factors of MP infection in various population. RESULTS: A total of 3,675 patients were enrolled and divided into three groups. One thousand and eighty-nine subjects (29.6%) were infected with at least one atypical pathogen. MP was the most predominant pathogen in these CAP patients. Our study found that infection rates of the atypical pathogens were significantly different among three groups. Our results also revealed, in a pediatric group, as the temperature increased, so did the infection rate of MP, while it was the opposite in adult and elderly groups. Furthermore, in preschool and school-age children, high temperature, female, PIVs, ADV, and INFB infection were independent risk factors for MP infection, INFA infection was a protection factor for MP infection. However, in adult and elderly groups, the associated factors might be different. CONCLUSIONS: The infection of atypical pathogens related with CAP is quite serious, and MP infection plays a key role in CAP. Besides, the infection rates of the atypical pathogens are different in various populations, as are the associated factors for MP infection.

12.
Biochem Biophys Res Commun ; 529(1): 7-14, 2020 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-32560821

RESUMO

This study aimed to investigate the role of truncated growth differentiation factor 11 (GDF11), in which the recognition site of Furin from wild-type GDF11 was deleted to enhance the cellular stability, in skin wound healing in the setting of diabetes mellitus (DM) and the underlying mechanisms. Our study found that both truncated and natural GDF11s effectively accelerated wound healing processes in both T1DM and T2DM mice with a potency compatible to PDGF, bFGF, and EGF, but being much higher than GDF8. At the cellular level, GDF11 stimulated the proliferation and suppressed HG-induced apoptosis of HSFs. Further study revealed that GDF11 activated the YAP-Smad2/3-CTGF fibrotic signaling pathway by reversing HG-induced upregulation of phosphorylated form of YAP (p-YAP), increases p-Smad2/3 levels, and restoring HG-induced repression of CTGF expression by GDF11. Overall, the study shows that both natural and truncated GDF11s promote the healing process of skin wound in mice of both T1DM and T2DM partly via stimulating dermal fibrosis via the YAP-Smad2/3-CTGF pathway, suggesting it a potential agent for treating skin wound in diabetic population.

13.
Environ Sci Pollut Res Int ; 27(27): 33965-33974, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32557062

RESUMO

The singlet and triplet potential energy surfaces of the HO2 with CF2ClO2 reaction have been probed at the BMC-CCSD/cc-pVTZ level according to the B3LYP/6-311++G(d,p) level obtained geometrical structure. On the singlet PES, the association/dissociation, direct H- abstraction, and SN2 displacement mechanisms have been taken into account. On the triplet PES, SN2 displacement and indirect H- abstraction reaction mechanisms have been investigated and the H- abstraction channel makes more contribution to the CF2ClO2 with HO2 reaction. The rate constants have been computed at 10-10 to 1010 atm and 200-3000 K by RRKM-TST theory. The results show that at T ≤ 600 K, the generation of IM1 (CF2ClO4H) by collisional deactivation is dominant pathway; at high temperatures, the production of P8 (CF2ClOOH + O2(3Σ)) becomes predominate. The predicted data for CF2ClO2 + HO2 agrees closely with available experimental value. Moreover, OH radicals act as inhibitors in the CF2ClOOH→CF2O + HOCl and CF2ClOOH→CFClO + HOF reactions. The dominant products for the reaction of CF2ClOOH + OH are CF2ClO2 + H2O.


Assuntos
Modelos Teóricos , Física , Cinética
14.
J Am Chem Soc ; 2020 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-32510205

RESUMO

Concerns about the toxicity of lead-based perovskites have aroused great interest for the development of alternative lead-free perovskite-type materials. Recently, theoretical calculations predict that Pb2+ cations can be substituted by a combination of Cu2+ and Sb3+ cations to form a vacancy-ordered layered double perovskite structure with superior optoelectronic properties. However, accessibilities to this class of perovskite-type materials remain inadequate, hindering their practical implementations in various applications. Here, we report the first colloidal synthesis of Cs4CuSb2Cl12 perovskite-type nanocrystals (NCs). The resulting NCs exhibit a layered double perovskite structure with ordered vacancies and a direct band gap of 1.79 eV. A composition-structure-property relationship has been established by investigating a series of Cs4CuxAg2-2xSb2Cl12 perovskite-type NCs (0 ≤ x ≤ 1). The composition induced crystal structure transformation, and thus, the electronic band gap evolution has been explored by experimental observations and further confirmed by theoretical calculations. Taking advantage of both the unique electronic structure and solution processability, we demonstrate that the Cs4CuSb2Cl12 NCs can be solution-processed as high-speed photodetectors with ultrafast photoresponse and narrow bandwidth. We anticipate that our study will prompt future research to design and fabricate novel and high-performance lead-free perovskite-type NCs for a range of applications.

15.
Phys Rev Lett ; 124(19): 193002, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32469599

RESUMO

The comagnetometer has been one of the most sensitive devices with which to test new physics related to spin-dependent interactions, but the comagnetometers based on overlapping ensembles of multiple spin species usually suffer from systematic errors due to magnetic field gradients. Here, we propose a comagnetometer based on the Zeeman transitions of the dual hyperfine levels in ground-state ^{87}Rb atoms, which shows nearly negligible sensitivity to variations of laser power and frequency, magnetic field, and magnetic field gradients. We measured the hypothetical spin-dependent gravitational energy of the proton with the comagnetometer, which is smaller than 4×10^{-18} eV, comparable to the most stringent existing constraint. Through optimizing the system parameters such as cell temperature, laser power, amplitude of driving magnetic field, as well as choosing better current source, it is possible to improve the sensitivity of the comagnetometer further.

16.
Opt Lett ; 45(10): 2930-2933, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32412503

RESUMO

We use a conventional linear Airy beam to prepare a nonlinear Airy beam via four-wave mixing (FWM) and six-wave mixing (SWM) processes in an atomic vapor. We find that its ballistic trajectory is a result of the competition between the transverse self-acceleration and nonlinear phase shift, and the intensity of Airy beam's sub lobes or main lobe is suppressed due to destructive interference of the FWM and SWM processes. By controlling the nonlinear overlap area of the linear Airy beam and two Gaussian beams, we find that the Airy beam's profile varies from one-dimensional (1D) to two-dimensional (2D). The profile evolution process can be applied to create a new (to our knowledge) type of nonlinear filter. In addition, we also observe the Airy beam's pattern in momentum space with electromagnetically induced transparency (EIT) in an atomic vapor. Our research results open up new possibilities for manipulating Airy beams that cannot be achieved with a conventional Airy beam.

17.
Talanta ; 216: 121017, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32456927

RESUMO

Absolute quantitation is always a challenge for in situ analysis of solid samples with ambient liquid extraction mass spectrometry due to unknown sampling efficiencies of analytes from complex solid matrices such as commercial packaging materials. Standards were usually dropped onto the sample surface for signal calibration, but the mass transfer of standards would not be the same as analytes distributed in samples. In this work, an in situ quantitation method via liquid microjunction sampling (LMJSS) coupled with mass spectrometry (MS) for photoinitiators (PIs) in packaging was developed without standard spiking. For direct in situ quantitation, mass transfer kinetic model for LMJSS of solid surface was proposed and validated. Results showed that the detection data well fitted the mass transfer model with adjusted R2 mostly in the range of 0.8-0.9 for 12 PIs in both lab-made mimetic positive samples and commercial packaging samples. According to the mass transfer kinetic model, two-point kinetic calibration method was proposed for calculation of the absolute concentration of PIs in solid samples by LMJSS of the same sample area for two times. The conditions of LMJSS including extraction solvent composition and solvent flowrate were optimized. With the optimized LMJSS-MS method and new calibration method, in situ analysis was done within only 2 min, and detection limits and quantitation limits of 15 PIs in mimetic samples were in the range of 0.06-1.5 mg/m2 and 0.34-6 mg/m2 respectively with relative standard deviation (RSDs) in the range of 2%-26%. The quantitation accuracy by the new calibration method for 13 PIs was in the range of 61%-162%. The method was applied to the quantitation of PIs in commercial packaging samples. 6 PIs were detected and identified in four commercial packaging materials, and the quantitation results were comparable with that by traditional solvent extraction-LC-MS method (relative recovery, 63%-127%).

18.
iScience ; 23(5): 101067, 2020 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-32371371

RESUMO

Current challenge for dynamic pathway control in metabolic engineering is enabling the components of the artificial regulatory system to be tunable. Here, we designed and built a heme-responsive regulatory system containing a heme biosensor HrtR and CRISPRi to regulate chemicals production while maintaining the intracellular heme homeostasis. A series of engineered biosensors with varied sensitivity and threshold were obtained by semi-rational design with site saturated mutation of HrtR. The modified metabolite-binding affinity of HrtR was confirmed by heme titration and molecular dynamic simulation. Dynamic regulation pattern of the system was validated by the fluctuation of gene expression and intracellular heme concentration. The efficiency of this regulatory system was proved by improving the 5-aminolevulinic acid (ALA) production to 5.35g/L, the highest yield in batch fermentation of Escherichia coli. This system was also successfully used in improving porphobilinogen (PBG) and porphyrins biosynthesis and can be applied in many other biological processes.

19.
Environ Sci Pollut Res Int ; 27(16): 20457-20468, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32242320

RESUMO

A global and systematic theoretical research on the singlet and triplet potential energy surfaces (PESs) of the CH2ClO2/CHCl2O2 with ClO reactions are done at the CCSD(T)//B3LYP level and accompanied with RRKM computations to forecast the mechanism and distribution of products. The simulation results revealed that, on the singlet PES, products P1 (CHClO + HO2 + Cl)/P1 (CCl2O + HO2 + Cl) from IM1 (CH2ClOOOCl)/IM1 (CHCl2OOOCl) are forecasted to the primary products of the CH2ClO2/CHCl2O2 + ClO reactions, which are initiated by the oxygen atom of ClO radical addition to the terminal-O atom of CH2ClO2/CHCl2O2 barrierlessly, while other product channels contribute less to the whole reactions owing to higher barriers. Two other isomers, including IM2 (CH2ClOOClO) and IM3 (CH2ClOClO2) for the CH2ClO2 + ClO reaction, and three other isomers, including IM2 (CHCl2OOClO), IM3 (CHCl2OClO2), and IM4 (CHCl2ClO3) for the CHCl2O2 + ClO reaction, could be produced as less significant products. RRKM calculations presented that the initial adducts IM1 (CH2ClOOOCl)/IM1 (CHCl2OOOCl) are the primary products at T < 400 K and T < 600 K, respectively, and products P1 (CHClO + HO2 + Cl)/P1 (CCl2O + HO2 + Cl) are dominant the reactions at T ≥ 400 K and T ≥ 600 K, respectively. The atmospheric lifetime of CH2ClO2 and CHCl2O2 in ClO is around 4.61 and 3.24 h, respectively.


Assuntos
Atmosfera , Oxigênio , Isomerismo
20.
Nat Mater ; 2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-32313265

RESUMO

Harvesting environmental energy to generate electricity is a key scientific and technological endeavour of our time. Photovoltaic conversion and electromechanical transduction are two common energy-harvesting mechanisms based on, respectively, semiconducting junctions and piezoelectric insulators. However, the different material families on which these transduction phenomena are based complicate their integration into single devices. Here we demonstrate that halide perovskites, a family of highly efficient photovoltaic materials1-3, display a photoflexoelectric effect whereby, under a combination of illumination and oscillation driven by a piezoelectric actuator, they generate orders of magnitude higher flexoelectricity than in the dark. We also show that photoflexoelectricity is not exclusive to halides but a general property of semiconductors that potentially enables simultaneous electromechanical and photovoltaic transduction and harvesting in unison from multiple energy inputs.

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