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1.
J Phys Chem A ; 128(28): 5500-5507, 2024 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-38968614

RESUMO

A series of anionic transition metal halides, OsCln- (n = 3-5), have been investigated using a newly developed, home-constructed, cryogenic anion cluster photoelectron spectroscopy. The target anionic species are generated through collision-induced dissociation in a two-stage ion funnel. The measured vertical detachment energies (VDEs) are 3.48, 4.54, and 4.81 eV for n = 3, 4, and 5, respectively. Density functional theory calculations at the B3LYP-D3(BJ)//aug-cc-pVTZ(-pp) level predict the lowest energy structures of the atomic form of OsCln- (n = 3-5) to be a quintet triangle, quartet square, and quintet square-based pyramid, respectively. The CCSD(T)-calculated VDEs and corresponding adiabatic detachment energies agree well with our experimental measurements. Analysis of the corresponding frontier molecular orbitals and charge density differences suggests that the d-orbitals of the transition metal Os play a primary role in the single-photon detachment processes, and the detached electrons originating from different molecular orbitals are distinguishable.

2.
BMC Anesthesiol ; 24(1): 222, 2024 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-38965472

RESUMO

BACKGROUND: Transfer to the ICU is common following non-cardiac surgeries, including radical colorectal cancer (CRC) resection. Understanding the judicious utilization of costly ICU medical resources and supportive postoperative care is crucial. This study aimed to construct and validate a nomogram for predicting the need for mandatory ICU admission immediately following radical CRC resection. METHODS: Retrospective analysis was conducted on data from 1003 patients who underwent radical or palliative surgery for CRC at Ningxia Medical University General Hospital from August 2020 to April 2022. Patients were randomly assigned to training and validation cohorts in a 7:3 ratio. Independent predictors were identified using the least absolute shrinkage and selection operator (LASSO) and multivariate logistic regression in the training cohort to construct the nomogram. An online prediction tool was developed for clinical use. The nomogram's calibration and discriminative performance were assessed in both cohorts, and its clinical utility was evaluated through decision curve analysis (DCA). RESULTS: The final predictive model comprised age (P = 0.003, odds ratio [OR] 3.623, 95% confidence interval [CI] 1.535-8.551); nutritional risk screening 2002 (NRS2002) (P = 0.000, OR 6.129, 95% CI 2.920-12.863); serum albumin (ALB) (P = 0.013, OR 0.921, 95% CI 0.863-0.982); atrial fibrillation (P = 0.000, OR 20.017, 95% CI 4.191-95.609); chronic obstructive pulmonary disease (COPD) (P = 0.009, OR 8.151, 95% CI 1.674-39.676); forced expiratory volume in 1 s / Forced vital capacity (FEV1/FVC) (P = 0.040, OR 0.966, 95% CI 0.935-0.998); and surgical method (P = 0.024, OR 0.425, 95% CI 0.202-0.891). The area under the curve was 0.865, and the consistency index was 0.367. The Hosmer-Lemeshow test indicated excellent model fit (P = 0.367). The calibration curve closely approximated the ideal diagonal line. DCA showed a significant net benefit of the predictive model for postoperative ICU admission. CONCLUSION: Predictors of ICU admission following radical CRC resection include age, preoperative serum albumin level, nutritional risk screening, atrial fibrillation, COPD, FEV1/FVC, and surgical route. The predictive nomogram and online tool support clinical decision-making for postoperative ICU admission in patients undergoing radical CRC surgery. TRIAL REGISTRATION: Despite the retrospective nature of this study, we have proactively registered it with the Chinese Clinical Trial Registry. The registration number is ChiCTR2200062210, and the date of registration is 29/07/2022.


Assuntos
Neoplasias Colorretais , Unidades de Terapia Intensiva , Nomogramas , Humanos , Masculino , Feminino , Estudos Retrospectivos , Pessoa de Meia-Idade , Neoplasias Colorretais/cirurgia , Idoso , Medição de Risco/métodos , Complicações Pós-Operatórias/epidemiologia , Admissão do Paciente
3.
Clin Appl Thromb Hemost ; 29: 10760296231216966, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37997283

RESUMO

Venous thromboembolism (VTE) is a life-threatening postoperative complication of malignant tumors. We identified risk factors for postoperative VTE in patients undergoing radical resection of colorectal cancer (CRC) and constructed and validated a clinical prediction model. Clinical data of 982 patients undergoing radical resection of CRC from September 1, 2020, to March 31, 2022, in Ningxia Medical University General Hospital were analyzed retrospectively. Patients were randomly divided into training (n = 617) and validation groups (n = 264). Data included baseline characteristics, preoperative complications, examination results, and intraoperative and postoperative indicators. Logistic regression analysis was used to determine risk factors, build a predictive model, and draw a predictive nomogram (CRSPOT). Receiver operating characteristics (ROC) curve was used to calculate the area under the curve (AUC) for evaluating the model's predictive ability. Independent risk factors for postoperative VTE were as follows: postoperative hemoglobin of <10 g/L (odds ratio [OR] 0.413, 95% confidence interval [CI] 0.220-0.777), postoperative D-dimer of ≥3.5µg/mL (OR 2.156, 95% CI 1.145-4.061), BMI of ≥25 kg/m2 (OR 2.313, 95% CI 1.225-4.369), operation time of ≥4 h (OR 2.292, 95% CI 1.232-4.262), lower extremity varicose veins (OR 4.499, 95% CI 1.764-11.476), postoperative ileus (OR 5.760, 95% CI 2.031-16.337), and postoperative hypoxemia (OR 9.230, 95% CI 4.562-18.672). The nomogram's AUC was 0.826, demonstrating a reliable predictive ability. The CRSPOT nomogram reliably predicts postoperative VTE in patients undergoing radical resection of CRC, identifying high-risk patients early, allowing early implementation of antithrombotic strategies, and helping to reduce the incidence and mortality of postoperative VTE.


Assuntos
Neoplasias Colorretais , Tromboembolia Venosa , Humanos , Nomogramas , Estudos Retrospectivos , Tromboembolia Venosa/epidemiologia , Prognóstico , Modelos Estatísticos , Fatores de Risco , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/epidemiologia , Neoplasias Colorretais/cirurgia , Neoplasias Colorretais/complicações
4.
Am J Case Rep ; 24: e940391, 2023 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-37491800

RESUMO

BACKGROUND Vasovagal syncope is a loss of consciousness caused by decreased arterial pressure and cerebral blood flow. The characteristic features of vasovagal syncope include cardiovascular inhibition caused by neural reflexes, accompanied by vasodilation and bradycardia. To date, there is little literature to report several episodes of syncope under spinal anesthesia during the perioperative period for drainage of an anal abscess. The purpose of this article is to alert clinical practitioners to the early identification of the underlying causes of vasovagal syncope and to facilitate timely and effective management strategies. CASE REPORT We present the case of a 44-year-old man with a perianal abscess who was scheduled for an incision and drainage procedure for the abscess under spinal anesthesia. Preoperative assessment revealed no history of cardiac disease, neurological disorders, or drug allergies. During the perioperative period, the patient experienced 3 episodes of syncope: 1 episode during puncture of spinal anesthesia, and the others at 6.5 h and 8.5 h after the procedure. The patient was discharged 4 days later, and a 30-day postoperative follow-up showed good recovery, without any episodes of syncope. CONCLUSIONS We described a case of 3 episodes of vasovagal syncope occurring in a patient during the perioperative period of drainage of perianal abscess under spinal anesthesia. Pain may have been the main cause of vasovagal syncope in this patient. To avoid vasovagal syncope, it is best for anesthesiologists to choose the lateral position to perform spinal anesthesia and to provide good perioperative pain management for these patients.


Assuntos
Raquianestesia , Doenças do Ânus , Síncope Vasovagal , Masculino , Humanos , Adulto , Síncope Vasovagal/etiologia , Raquianestesia/efeitos adversos , Abscesso/etiologia , Abscesso/cirurgia , Síncope , Drenagem/efeitos adversos , Dor
5.
Environ Pollut ; 325: 121429, 2023 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-36906060

RESUMO

A cataclysmic submarine volcano at Hunga Tonga-HungaHa'apai (HTHH) near Tonga, erupted violently on 15 January 2022, which injected a plume of ash cloud soaring into the upper atmosphere. In this study, we examined the regional transportation and potential influence of atmospheric aerosols triggered by HTHH volcano, based on active and passive satellite products, ground-based observations, multi-source reanalysis datasets and atmospheric radiative transfer model. The results indicated that about 0.7 Tg (1 Tg = 109 kg) sulfur dioxide (SO2) gas were emitted into stratosphere from the HTHH volcano, and were lifted to an altitude of 30 km. The regional averaged SO2 columnar content over the western Tonga increased by 10-36 Dobson Units (DU), and the mean aerosol optical thickness (AOT) retrieved from satellite products increased to 0.25-0.34. The stratospheric AOT values caused by HTHH emissions increased to 0.03, 0.20, and 0.23 on 16, 17, and 19 January, respectively, accounting for 1.5%, 21.9%, and 31.1% of total AOT. Ground-based observations also showed an AOT increase of 0.25-0.43, with the maximum daily average of 0.46-0.71 appeared on 17 January. The volcanic aerosols were remarkably dominated by fine-mode particles and posed strong light-scattering and hygroscopic abilities. Consequently, the mean downward surface net shortwave radiative flux was reduced by 2.45-11.9 Wm-2 on different regional scales, and the surface temperature decreased by 0.16-0.42 K. The maximum aerosol extinction coefficient was 0.51 km-1 appeared at 27 km, which resulted in an instantaneous shortwave heating rate of 1.80 Khour-1. These volcanic materials stayed stable in the stratosphere and completed one circle around the earth within 15 days. This would exert a profound influence on the energy budget, water vapor and ozone exchange in the stratosphere, which deserves to be further studied.


Assuntos
Atmosfera , Erupções Vulcânicas , Tonga , Atmosfera/análise , Dióxido de Enxofre , Aerossóis
6.
Mar Pollut Bull ; 187: 114521, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36621299

RESUMO

Human vibriosis, caused by pathogenic Vibrio spp., such as Vibrio parahaemolyticus, Vibrio cholerae and Vibrio vulnificus, has been increasing worldwide, mediated by increasing consumption of seafood. The present study was conducted to examine the global prevalence of V. vulnificus, V. parahaemolyticus and V. cholerae in fishes. We searched PubMed, Web of Science, Scopus, and CNKI for peer-reviewed articles and dissertations prior to December 31, 2021. A total of 24,831 articles were retrieved, and 82 articles contained 61 fish families were included. The global pooled prevalence of V. cholerae, V. parahaemolyticus and V. vulnificus in fishes was 9.56 % (95 % CI: 2.12-20.92), 24.77 % (95 % CI: 17.40-32.93) and 5.29 % (95 % CI: 0.38-13.61), respectively. Subgroup and meta-regression analyses showed that study-level covariates, including temperature, country, continent, origin and detection methods partly explained the between-study heterogeneity. These heterogeneities were underpinned by differences of the three Vibrio spp. in fishes at geographical and climatic scales. These results reveal a high global prevalence of pathogenic Vibrio spp. in fishes and highlight the need for implementation of more effective prevention and control measures to reduce food-borne infection in humans.


Assuntos
Vibrioses , Vibrio cholerae , Vibrio parahaemolyticus , Vibrio , Animais , Humanos , Saúde Pública , Prevalência , Alimentos Marinhos , Vibrioses/epidemiologia , Vibrioses/veterinária , Peixes
7.
Front Vet Sci ; 9: 792346, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35265693

RESUMO

Anisakidosis, caused by anisakid larvae, is an important fish-borne zoonosis. This study aimed to summarize the prevalence of anisakid infection in fish in China. A systematic review and meta-analysis were performed using five bibliographic databases (PubMed, CNKI, ScienceDirect, WanFang, and VIP Chinese Journal Databases). A total of 40 articles related to anisakid infection in fish in China were finally included. Anisakid nematodes were prevalent in a wide range of fish species, and the overall pooled prevalence of anisakid nematodes in fish in China was 45.5%. Fresh fish had the highest prevalence rate (58.1%). The highest prevalence rate was observed in Eastern China (55.3%), and fish from East China Sea showed the highest prevalence of anisakid nematodes (76.8%). Subgroup analysis by sampling year suggested that the infection rate was higher during the years 2001-2011 (51.0%) than the other periods. Analysis of study quality revealed that the middle-quality studies reported the highest prevalence (59.9%). Compared with other seasons, winter had the highest prevalence (81.8%). The detection rate of anisakid nematodes in muscle was lower (7.8%, 95% CI: 0.0-37.6) than in other fish organs. Our findings suggested that anisakid infection was still common among fish in China. We recommend avoiding eating raw or undercooked fish. Region, site of infection, fish status and quality level were the main risk factors, and a continuous monitoring of anisakid infection in fish in China is needed.

8.
Transbound Emerg Dis ; 69(5): e1213-e1230, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35195942

RESUMO

Toxoplasma gondii infection in wild marine mammals is a growing problem and is associated with adverse impacts on marine animal and public health. This systematic review, meta-analysis and meta-regression estimates the global prevalence of T. gondii infection in wild marine mammals and analyses the association between T. gondii infection and epidemiological variables. PubMed, Web of Science, Science Direct, China National Knowledge Infrastructure, and Wanfang Data databases were searched until 30 May 2021. Eighty-four studies (n = 14,931 wild marine mammals from 15 families) were identified from literature. The overall pooled prevalence of T. gondii infection was 22.44% [3848/14,931; 95% confidence interval (CI): 17.29-28.04]. The prevalence in adult animals 21.88% (798/3119; 95% CI: 13.40-31.59) was higher than in the younger age groups. North America had a higher prevalence 29.92% (2756/9243; 95% CI: 21.77-38.77) compared with other continents. At the country level, the highest prevalence was found in Spain 44.26% (19/88; 95%CI: 5.21-88.54). Regarding climatic variables, the highest prevalence was found in areas with a mean annual temperature >20°C 36.28% (171/562; 95% CI: 6.36-73.61) and areas with an annual precipitation > 800 mm 26.92% (1341/5042; 95% CI: 18.20-36.59). The subgroup and meta-regression analyses showed that study-level covariates, including age, country, continent, and mean temperature, partly explained the between-study heterogeneity. Further studies are needed to investigate the source of terrestrial to aquatic dissemination of T. gondii oocysts, the fate of this parasite in marine habitat and its effects on wild marine mammals.


Assuntos
Caniformia , Toxoplasma , Toxoplasmose Animal , Toxoplasmose , Animais , Cetáceos , Oocistos , Prevalência , Estudos Soroepidemiológicos , Toxoplasmose/epidemiologia , Toxoplasmose Animal/epidemiologia , Toxoplasmose Animal/parasitologia
9.
Sci Total Environ ; 806(Pt 2): 150562, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34852432

RESUMO

The aim of this review is to identify the worldwide trend of waterborne protozoan outbreaks and how it varies between geographic regions during the period from 2017 to 2020. Data about waterborne protozoan outbreaks were gathered and stratified by continent, country, water source, and protozoan species associated with the outbreak. The highest prevalence of waterborne protozoan outbreaks was reported in developed countries. Out of 251 outbreaks reported worldwide during the studied period, 141, 51 and 24 outbreaks were recorded in the USA, UK, and New Zealand, respectively. These outbreaks were mainly associated with Cryptosporidium (192 outbreaks) and Giardia (48 outbreaks). Cyclospora cayetanensis, Dientamoebafragilis and Toxoplasma gondii were associated with 7 outbreaks. One outbreak was associated with each of Blastocystis hominis, Entamoeba histolytica, Microsporidia or Naegleria fowleri. This data suggests large discrepancies in the number of outbreaks reported between geographic regions, with most outbreaks recorded in developed countries. Differences in the prevalence of outbreaks between countries are likely attributed to the availability of diagnostic capabilities and surveillance programs to monitor water contamination with pathogenic protozoa. More attention and concerted efforts are required to improve water safety and to alleviate the impact of waterborne protozoan infections. Appropriate surveillance of water contamination with protozoa can enable public health officials to identify source of contamination and implement the necessary measures to limit transmission and prevent outbreaks.


Assuntos
Criptosporidiose , Cryptosporidium , Giardíase , Criptosporidiose/epidemiologia , Surtos de Doenças , Giardíase/epidemiologia , Humanos , Prevalência
10.
Phys Rev Lett ; 127(18): 183201, 2021 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-34767394

RESUMO

Probing transient charge localization in the innershell orbital of atoms and molecules has been made possible by the recent progress of advanced light sources. Here, we demonstrate that the ultrafast electron tunneling ionization by an intense femtosecond laser pulse could induce an asymmetric transient charge localization in the valence shell of the HCl molecule during the dissociative ionization process. The transient charge localization is encoded in the laser impulse acquired by the outgoing ionic fragments, and the asymmetry is revealed by carefully examining the electron tunneling-site distinguished momentum angular distribution of the ejected H^{+} fragments. Our work proposes a way to visualize the transient valence charge motion and will stimulate further investigations of the tunneling-site-sensitive ultrafast dynamics of molecules in strong laser fields.

11.
Ecotoxicol Environ Saf ; 213: 112048, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33610941

RESUMO

We conducted a large-scale epidemiological investigation to detect the prevalence of Toxoplasma gondii in four marine bivalve shellfish species collected from six representative coastal regions of Weihai, eastern China. Between January 2018 and December 2018, 14,535 marine bivalve shellfish pooled into 2907 samples were randomly collected and examined for T. gondii DNA by a nested PCR assay targeting B1 gene. The results showed that 2.8% (82) of the 2907 pooled samples were tested positive for T. gondii DNA. Two T. gondii genotype (ToxoDB Genotype #9 and ToxoDB Genotype #1) were identified PCR-restriction fragment length polymorphism analysis. Factors that were found significantly associated with the presence of T. gondii DNA in marine bivalve shellfish included the source of samples (being wild) (odds ratio [OR], 3.34; 95% confidence interval [CI], 2.00-5.84; p < 0.01), surface runoff near the sampling site (OR, 2.64; 95% CI, 1.47-4.72; p < 0.01), and presence of cats near the sampling site (OR, 1.77; 95% CI, 1.02-3.07; p = 0.04). Moreover, the prevalence of T. gondii DNA in marine bivalve shellfish correlated with temperature (Pearson's correlation: R = 0.75, p = 0.0049) and precipitation (R = 0.87, p = 0.00021). These findings provide new insights into the presence of T. gondii DNA in marine bivalve shellfish and highlight the impact of human activity on marine pollution by such an important terrestrial pathogen pollutant.


Assuntos
Bivalves/parasitologia , Toxoplasmose Animal/epidemiologia , Animais , Bivalves/genética , China/epidemiologia , Genótipo , Humanos , Reação em Cadeia da Polimerase/métodos , Prevalência , Fatores de Risco , Frutos do Mar , Toxoplasma/genética
12.
Nat Chem ; 13(2): 182-190, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33318674

RESUMO

Transition-metal-catalysed, redox-neutral dehydrosilylation of alkenes is a long-standing challenge in organic synthesis, with current methods suffering from low selectivity and narrow scope. In this study, we report a general and simple method for the manganese-catalysed dehydrosilylation and hydrosilylation of alkenes, with Mn2(CO)10 as a catalyst precursor, by using a ligand-tuned metalloradical reactivity strategy. This enables versatility and controllable selectivity with a 1:1 ratio of alkenes and silanes, and the synthetic robustness and practicality of this method are demonstrated using complex alkenes and light olefins. The selectivity of the reaction has been studied using density functional theory calculations, showing the use of an iPrPNP ligand to favour dehydrosilylation, while a JackiePhos ligand favours hydrosilylation. The reaction is redox-neutral and atom-economical, exhibits a broad substrate scope and excellent functional group tolerance, and is suitable for various synthetic applications on a gram scale.

13.
Acta Trop ; 214: 105779, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33253657

RESUMO

Increasing evidence exisits for the role that shellfish play in the epidemiology of Toxoplasma gondii in marine environment. However, limited information is available on the level of T. gondii infection in wild marine snails, which can play a role in the transmission of T. gondii to other marine organisms and humans. In this study, the prevalence of T. gondii DNA in wild marine snails collected from three coastal cities in China was determined. Between January 2018 and November 2019, 1,206 wild marine snails were randomly collected and examined for the presence of T. gondii DNA using a nested polymerase chain reaction (PCR) targeting T. gondii B1 gene. The amplified products were genotyped using multilocus PCR-restriction fragment length polymorphism analysis. We also examined whether species of snail, sampling region, sampling season, surface runoff near samplic site, residential water discharge near samplic site, and proximity to livestock farms are associated with the occurrence of T. gondii DNA in marine snails. Our results showed that 23 (1.91%) snails were positive for T. gondii B1 gene. The genotype of two of the 23 T. gondii amplicons was consistent with ToxoDB Genotype #9. Multiple logistic regression revealed that surface runoff near the sampling site (P = 0.039, odds ratio [OR] = 3.413, 95% confidence interval [CI]: 1.07-10.94) and residential water discharge near the sampling site (P = 0.021, OR = 3.990, 95%CI: 1.24-12.87) are more likely to be associated with the presence of T. gondii DNA in marine snails. The detection of T. gondii DNA in marine snails in China highlights the potential impact of the anthropogenic activities on marine organisms and the potential foodborne risk posed to humans with such an important terrestrial pathogen.


Assuntos
DNA de Protozoário/isolamento & purificação , Genótipo , Caramujos/parasitologia , Toxoplasma/genética , Animais , China/epidemiologia , DNA de Protozoário/genética , Humanos , Modelos Logísticos , Razão de Chances , Reação em Cadeia da Polimerase/veterinária , Fatores de Risco , Toxoplasma/isolamento & purificação
14.
Phys Rev Lett ; 123(23): 233202, 2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31868470

RESUMO

We experimentally observe the bond stretching time of one-photon and net-two-photon dissociation pathways of singly ionized H_{2} molecules driven by a polarization-skewed femtosecond laser pulse. By measuring the angular distributions of the ejected photoelectron and nuclear fragments in coincidence, the cycle-changing polarization of the laser field enables us to clock the photon-ionization starting time and photon-dissociation stopping time, analogous to a stopwatch. After the single ionization of H_{2}, our results show that the produced H_{2}^{+} takes almost the same time in the one-photon and net-two-photon dissociation pathways to stretch to the internuclear distance of the one-photon coupled dipole-transition between the ground and excited electronic states. The spatiotemporal mapping character of the polarization-skewed laser field provides us a straightforward route to clock the ultrafast dynamics of molecules with sub-optical-cycle time resolution.

15.
Nat Commun ; 10(1): 5780, 2019 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-31852905

RESUMO

Quantum coherence plays an essential role in diverse natural phenomena and technological applications. The unavoidable coupling of the quantum system to an uncontrolled environment incurs dissipation that is often described using the secular approximation. Here we probe the limit of this approximation in the rotational relaxation of molecules due to thermal collisions by using the laser-kicked molecular rotor as a model system. Specifically, rotational coherences in N2O gas (diluted in He) are created by two successive nonresonant short and intense laser pulses and probed by studying the change of amplitude of the rotational alignment echo with the gas density. By interrogating the system at the early stage of its collisional relaxation, we observe a significant variation of the dissipative influence of collisions with the time of appearance of the echo, featuring a decoherence process that is well reproduced by the nonsecular quantum master equation for modeling molecular collisions.

16.
Chemistry ; 25(55): 12724-12729, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31441136

RESUMO

An unprecedented deoxygenative arylation of aromatic carboxylic acids has been achieved, allowing the construction of an enhanced library of unsymmetrical diaryl ketones. The synergistic photoredox catalysis and phosphoranyl radical chemistry allows for precise cleavage of a stronger C-O bond and formation of a weaker C-C bond by 1,5-aryl migration under mild reaction conditions. This new protocol is independent of substrate redox-potential, electronic, and substituent effects. It affords a general and promising access to 60 examples of synthetically versatile o-amino and o-hydroxy diaryl ketones under redox-neutral conditions. Furthermore, it also brings one concise route to the total synthesis of quinolone alkaloid, (±)-yaequinolone A2, and a viridicatin derivative in satisfying yields.

17.
Phys Rev Lett ; 122(19): 193401, 2019 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-31144959

RESUMO

We show that recently discovered rotational echoes of molecules provide an efficient tool for studying collisional molecular dynamics in high-pressure gases. Our study demonstrates that rotational echoes enable the observation of extremely fast collisional dissipation, at timescales of the order of a few picoseconds, and possibly shorter. The decay of the rotational alignment echoes in CO_{2} gas and CO_{2}-He mixture up to 50 bar was studied experimentally, delivering collision rates that are in good agreement with the theoretical expectations. The suggested measurement protocol may be used in other high-density media, and potentially in liquids.

18.
Nat Commun ; 10(1): 757, 2019 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-30765696

RESUMO

Atoms and molecules exposed to strong laser fields can be excited to the Rydberg states with very high principal quantum numbers and large orbitals. It allows acceleration of neutral particles, generate near-threshold harmonics, and reveal multiphoton Rabi oscillations and rich photoelectron spectra. However, the physical mechanism of Rydberg state excitation in strong laser fields is yet a puzzle. Here, we identify the electron-nuclear correlated multiphoton excitation as the general mechanism by coincidently measuring all charged and neutral fragments ejected from a H2 molecule. Ruled by the ac-Stark effect, the internuclear separation for resonant multiphoton excitation varies with the laser intensity. It alters the photon energy partition between the ejected electrons and nuclei and thus leads to distinct kinetic energy spectra of the nuclear fragments. The electron-nuclear correlation offers an alternative visual angle to capture rich ultrafast processes of complex molecules.

19.
Nat Commun ; 9(1): 5134, 2018 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-30510201

RESUMO

Orientation and alignment of molecules by ultrashort laser pulses is crucial for a variety of applications and has long been of interest in physics and chemistry, with the special emphasis on stereodynamics in chemical reactions and molecular orbitals imaging. As compared to the laser-induced molecular alignment, which has been extensively studied and demonstrated, achieving molecular orientation is a much more challenging task, especially in the case of asymmetric-top molecules. Here, we report the experimental demonstration of all-optical field-free three-dimensional orientation of asymmetric-top molecules by means of phase-locked cross-polarized two-color laser pulse. This approach is based on nonlinear optical mixing process caused by the off-diagonal elements of the molecular hyperpolarizability tensor. It is demonstrated on SO2 molecules and is applicable to a variety of complex nonlinear molecules.

20.
Angew Chem Int Ed Engl ; 57(32): 10357-10361, 2018 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-29952053

RESUMO

The first transition-metal-free, site-specific umpolung trifluoromethylthiolation of tertiary alkyl ethers has been developed, achieving the challenging tertiary C(sp3 )-SCF3 coupling under redox-neutral conditions. The synergism of organophotocatalyst 4CzIPN and BINOL-based phosphorothiols can site-selectively cleave tertiary sp3 C(sp3 )-O ether bonds in complex molecules initiated by a polarity-matching hydrogen-atom-transfer (HAT) event. The incorporation of several competing benzylic and methine C(sp3 )-H bonds in alkyl ethers has little influence on the regioselectivity. Selective difluoromethylthiolation of C-O bonds has also been achieved. This represents not only an important step forward in trifluoromethylthiolation but also a promising means for site-selective C-O bond functionalization of unsymmetrical tertiary alkyl ethers.

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