Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 82
Filtrar
Más filtros

Bases de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
Cancer ; 130(S8): 1403-1414, 2024 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-37916832

RESUMEN

INTRODUCTION: Breast cancer is a significant contributor to female mortality, exerting a public health burden worldwide, especially in China, where risk-prediction models with good discriminating accuracy for breast cancer are still scarce. METHODS: A multicenter screening cohort study was conducted as part of the Cancer Screening Program in Urban China. Dwellers aged 40-74 years were recruited between 2014 and 2019 and prospectively followed up until June 30, 2021. The entire data set was divided by year of enrollment to develop a prediction model and validate it internally. Multivariate Cox regression was used to ascertain predictors and develop a risk-prediction model. Model performance at 1, 3, and 5 years was evaluated using the area under the curve, nomogram, and calibration curves and subsequently validated internally. The prediction model incorporates selected factors that are assigned appropriate weights to establish a risk-scoring algorithm. Guided by the risk score, participants were categorized into low-, medium-, and high-risk groups for breast cancer. The cutoff values were chosen using X-tile plots. Sensitivity analysis was conducted by categorizing breast cancer risk into the low- and high-risk groups. A decision curve analysis was used to assess the clinical utility of the model. RESULTS: Of the 70,520 women enrolled, 447 were diagnosed with breast cancer (median follow-up, 6.43 [interquartile range, 3.99-7.12] years). The final prediction model included age and education level (high, hazard ratio [HR], 2.01 [95% CI, 1.31-3.09]), menopausal age (≥50 years, 1.34 [1.03-1.75]), previous benign breast disease (1.42 [1.09-1.83]), and reproductive surgery (1.28 [0.97-1.69]). The 1-year area under the curve was 0.607 in the development set and 0.643 in the validation set. Moderate predictive discrimination and satisfactory calibration were observed for the validation set. The risk predictions demonstrated statistically significant differences between the low-, medium-, and high-risk groups (p < .001). Compared with the low-risk group, women in the high- and medium-risk groups posed a 2.17-fold and 1.62-fold elevated risk of breast cancer, respectively. Similar results were obtained in the sensitivity analyses. A web-based calculator was developed to estimate risk stratification for women. CONCLUSIONS: This study developed and internally validated a risk-adapted and user-friendly risk-prediction model by incorporating easily accessible variables and female factors. The personalized model demonstrated reliable calibration and moderate discriminative ability. Risk-stratified screening strategies contribute to precisely distinguishing high-risk individuals from asymptomatic individuals and prioritizing breast cancer screening. PLAIN LANGUAGE SUMMARY: Breast cancer remains a burden in China. To enhance breast cancer screening, we need to incorporate population stratification in screening. Accurate risk-prediction models for breast cancer remain scarce in China. We established and validated a risk-adapted and user-friendly risk-prediction model by incorporating routinely available variables along with female factors. Using this risk-stratified model helps accurately identify high-risk individuals, which is of significant importance when considering integrating individual risk assessments into mass screening programs for breast cancer. Current clinical breast cancer screening lacks a constructive clinical pathway and guiding recommendations. Our findings can better guide clinicians and health care providers.


Asunto(s)
Neoplasias de la Mama , Humanos , Femenino , Neoplasias de la Mama/diagnóstico , Neoplasias de la Mama/epidemiología , Estudios Prospectivos , Estudios de Cohortes , Detección Precoz del Cáncer , Medición de Riesgo
2.
Chemistry ; 30(6): e202302904, 2024 Jan 26.
Artículo en Inglés | MEDLINE | ID: mdl-37936501

RESUMEN

A highly enantioselective Mannich reaction of biphenyl-bridged seven-membered cyclic N-sulfonylimines with methyl alkyl ketones is disclosed in this study. The reaction was performed under organocatalysis by using a quinine-derived primary amine as the catalyst in combination with a Brønsted acid as the co-catalyst. High yields (up to 89 %) and excellent enantioselectivities (up to 97 % ee) were observed. For methyl alkyl ketones containing a larger alkyl substituent, specific regioselective addition to the C=N bond is favored at the methyl group. On the contrary, ketones containing a smaller alkyl substituent or hydroxyacetone substrates gave major syn selective Mannich products at the methylene group.

3.
J Org Chem ; 89(5): 3573-3579, 2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38377489

RESUMEN

A BF3·OEt2-catalyzed synthesis of carboranylated dihydropyrrolo[1,2-a]quinoxalines and dihydroindolo[1,2-a]quinoxalines in 30-99% yields is presented through the heterocyclization of various C-modified C-formyl-o-carboranes with 1-(2-aminophenyl)-pyrroles/indoles. A systematic comparative investigation of their oxidation stability in air confirmed that 4-carboranyl-4,5-dihydropyrrolo[1,2-a]quinoxaline had better stability than the 4-phenyl analogue. A cage-deboronation reaction for N-acetyl-substituted carboranylated dihydropyrrolo[1,2-a]quinoxaline produced the corresponding 7,8-nido-carborane cesium salt. A kinetic resolution was also realized to obtain an optically pure carboranylated N-heterocycle scaffold bearing a carborane cage carbon-bonded chiral stereocenter.

4.
J Gastroenterol Hepatol ; 37(7): 1235-1243, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35434850

RESUMEN

BACKGROUND AND AIM: Though one-size-fits-all age-based screening for colorectal cancer (CRC) is effective in reducing the incidence and mortality, the evidence regarding on personized screening based on individual risk factors has been growing. The study aimed to perform a systematic review to synthesize economic evidence of risk-tailored CRC screening strategies. METHODS: This systematic review was conducted in EMBASE, Web of Science, PubMed, Cochrane Library, Econlit, and National Institute for Health Research Economic Evaluation Database from inception to June 30, 2021. We calculated the incremental cost-effectiveness ratio (ICER) of cost per life year or quality-adjusted life year gained for the risk-tailored screening compared with no screening or uniform screening. A strategy was cost-effective with less cost and equal or more effectiveness than the comparator along with lower ICER than the willingness-to-pay threshold. RESULTS: Our review finally comprised seven studies. Five studies reported the results of comparisons of risk-tailored CRC screening with no screening, and supported that risk-tailored screening was cost-effective. All of seven studies reported the ICERs of risk-tailored screening and age-based screening. Disparities in the discrimination of risk-prediction tool, accuracy of adopted techniques, uptake rate of screening and cost estimation impacted the cost-effectiveness. CONCLUSIONS: Studies on the economic evaluation of risk-tailored CRC screening are limited, and current evidence is not sufficient to support the replacement of risk-tailored screening for traditional age-based screening.


Asunto(s)
Neoplasias Colorrectales , Detección Precoz del Cáncer , Neoplasias Colorrectales/diagnóstico , Neoplasias Colorrectales/prevención & control , Análisis Costo-Beneficio , Detección Precoz del Cáncer/métodos , Humanos , Incidencia , Años de Vida Ajustados por Calidad de Vida
5.
Nanotechnology ; 32(47)2021 Aug 31.
Artículo en Inglés | MEDLINE | ID: mdl-34359054

RESUMEN

In order to solve the 'ultraviolet (UV) filtering problem' caused by traditional sandwich-type structure in photoelectrochemical (PEC) UV detector, we design a special electrode based on stainless steel mesh, which integrates the light absorption layer and the electron collection electrode in a simple way. In combination with an UV-transparent quartz substrate, UV light can directly reach the active material. The improved detector shows good visible-blind, self-powered, and linear response characteristics. The serious recombination caused by metal electrode is suppressed by depositing a barrier layer. The optimized device exhibits a high photoresponse of 0.103 A W-1at 296 nm, a short recovery time of 250 ms, and very sensitive switching ability. Furthermore, the response range of the detector is expanded from 300 to 400 nm to the full near-UV region. Our work provides an efficient strategy to solve the key problem of the PEC UV detector.

6.
J Org Chem ; 85(17): 11331-11339, 2020 09 04.
Artículo en Inglés | MEDLINE | ID: mdl-32786629

RESUMEN

A simple chiral primary-tertiary diamine derived from C2-symmetric 1,2-diphenylethane-1,2-diamine as the organocatalyst in combination with the trifluoroacetic acid additive for the asymmetric Mannich reaction of cyclic N-sulfonyl trifluoromethylated ketimines and methyl ketones afforded the desired product with high enantioselectivity (73-96% ee). The reactions proceeded well for a variety of different substituted cyclic N-sulfonyl trifluoromethyl ketimines and various alkyl methyl ketones, providing access to diverse enantioenriched benzo-fused cyclic sulfamidate N-heterocycles bearing a trifluoromethylated α-tetrasubstituted carbon stereocenter. This study also investigated the diastereoselective reduction of the carbonyl group and ring cleavage reduction of the sulfamidate group of the corresponding Mannich product.

7.
Cost Eff Resour Alloc ; 18: 33, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32944005

RESUMEN

BACKGROUND: This study aimed to examine the cost-effectiveness of one-time standard endoscopic screening with Lugol's iodine staining for esophageal cancer (EC) in China. METHODS: A Markov decision analysis model with eleven states was built. Individuals aged 40 to 69 years were classified into six age groups in five-year intervals. Three different strategies were adopted for each cohort: (1) no screening; (2) one-time endoscopic screening with Lugol's iodine staining with an annual follow-up for low-grade intraepithelial neoplasia (LGIN); and (3) one-time endoscopic screening with Lugol's iodine staining without follow-up. Quality-adjusted life-years (QALYs) indicated the effectiveness of the model. The incremental cost-effectiveness ratio (ICER) was used as the evaluation indicator. Sensitivity analysis was performed to assess the robustness of the model. RESULTS: One-time screening with follow-up was the undominated strategy for individuals aged 40-44 and 45-49 years, which saved USD 10,942.57 and USD 6611.73 per QALY gained compared to nonscreening strategy. For those aged 50-69 years, the nonscreening scenarios were undominated. One-time screening without follow-up was the extended dominated strategy. Compared to screening strategies without follow-up, all the screening strategies with follow-up were more cost-effective, with the ICER increasing from 299.57 USD/QALY for individuals aged 40-44 years to 1617.72 USD/QALY for individuals aged 65-69 years. Probabilistic sensitivity analysis (PSA) supported the results of the base case analysis. CONCLUSIONS: One-time EC screening with follow-up targeting individuals aged 40-49 years was the most cost-effective strategy.

8.
Chin J Cancer Res ; 31(1): 144-151, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-30996572

RESUMEN

OBJECTIVE: To analyze the incidence and mortality rates of thyroid cancer (TC) in China from 2008 to 2012. METHODS: Incident and death cases of TC were retrieved from the National Central Cancer Registry (NCCR) database collecting from 135 cancer registries in China during 2008-2012. The crude incidence and mortality rates of TC were calculated by area (urban/rural), region (eastern, middle, western), gender and age group (0, 1-4, 5-9, …, 85+). China census in 2000 and world Segi's population were applied for age-standardized rates. Joinpoint (Version 4.6.0.0) model was used for time-trend analysis. RESULTS: The crude incidence rate of TC was 7.56/100,000 which ranked the seventh in overall cancers. The age-standardized incidence rates by China population (ASIRC) and by World population (ASIRW) were 6.25/100,000 and 5.52/100,000, respectively. The crude mortality of TC in China was 0.52/100,000. The age-standardized mortality rates by Chinese standard population (ASMRC) and by world standard population (ASMRW) were 0.34/100,000 and 0.32/100,000, respectively. Incidence and mortality rates of TC were higher in females than in males and higher in urban areas than in rural areas. Eastern areas had the highest incidence followed by middle and western areas. TC incidence increased dramatically after age of 15 years, then peaked at 14.08/100,000 in the group of 50-54 years and finally decreased sharply after 55 years old. TC mortality increased with age in population, reaching the peak of 5.09/100,000 in sub-population aged 85 years or older. TC incidence increased by 4.73 times from 2.40/100,000 in 2003 to 13.75/100,000 in 2012 with an average annual increase of 20%, while TC mortality only increased slightly around 0.32/100,000 from 0.26/100,000 to 0.36/100,000. CONCLUSIONS: Appropriate targeted prevention, early detection and treatment programs can be carried out to curb the rapid growth trend of TC and control the disease burden.

9.
BMC Cancer ; 18(1): 291, 2018 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-29544469

RESUMEN

BACKGROUND: Thyroid cancer is the most common malignant disease of the endocrine system. Previous studies indicate a rapid increase in the incidence of thyroid cancer in recent decades, and this increase has aroused the great public concern. The aim of this study was to analyze the trends in incidence, mortality and clinical-pathological patterns of thyroid cancer in Zhejiang province. METHODS: Population-based incidence and mortality rates of thyroid cancer were collected from eight cancer registries in Zhejiang from 2000 to 2012. The incidence and mortality rates were age-standardized to Segi's world population. A Joinpoint model was used to examine secular trends in age-adjusted thyroid cancer rates with the Joinpoint Regression Program Version 4.0.0. Thyroid cancer patients were recruited from Zhejiang Cancer Hospital from 1972 to 2014. Patient demographics, tumor histology and tumor size were compared among the different periods of 1972-1985, 1986-1999 and 2000-2014. RESULTS: The age-standardized incidence rate of thyroid cancer in Zhejiang cancer registries was 2.75/105 in 2000, and increased to 19.42/105 in 2012. Additionally, we observed significantly increasing incidence rates with the Annual Percent Change (APC) of 22.86% (95%CI, 19.2%-26.7%). The age-standardized mortality of thyroid cancer in Zhejiang cancer registries was 0.23/105 in 2000 and 0.25/105 in 2012. No significant change in mortality rate was found. We observed a rapid increase in the proportions of papillary thyroid carcinoma (PTC) in 12,508 patients with thyroid carcinoma identified in the Zhejiang Cancer Hospital from 1972 to 2014 while the proportions of poorly differentiated thyroid cancer (PDTC), medullary thyroid carcinoma (MTC) and follicular thyroid carcinoma (FTC) decreased over the decades. In the PTC cases, the proportion of patients with maximum tumor diameter (MTD) < 1 cm dramatically and significantly increased from 0 in 1972-1985 to 32.1% in 2000-2014. CONCLUSIONS: A rapid increase in incidence and a stable trend in mortality of thyroid cancer were found in the distribution of thyroid cancer. Most of the increased incidence was PTC, especially the papillary thyroid microcarcinoma (PTMC) with MTD < 1 cm. This increase in incidence might be due to increased diagnosis with advanced technology.


Asunto(s)
Mortalidad/tendencias , Neoplasias de la Tiroides/epidemiología , Neoplasias de la Tiroides/mortalidad , Adenocarcinoma Folicular/epidemiología , Adenocarcinoma Folicular/mortalidad , Adenocarcinoma Folicular/patología , Adulto , Factores de Edad , Carcinoma Medular/epidemiología , Carcinoma Medular/mortalidad , Carcinoma Medular/patología , Carcinoma Papilar/epidemiología , Carcinoma Papilar/mortalidad , Carcinoma Papilar/patología , China/epidemiología , Femenino , Estudios de Seguimiento , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Pronóstico , Sistema de Registros , Factores Sexuales , Tasa de Supervivencia , Neoplasias de la Tiroides/patología , Adulto Joven
10.
BMC Psychiatry ; 18(1): 115, 2018 04 27.
Artículo en Inglés | MEDLINE | ID: mdl-29703173

RESUMEN

BACKGROUND: Life event assessment is an important part in psychological autopsy, and how to integrate its proxy data from two informants is a major methodological issue which needs solving. METHODS: Totally 416 living subjects and their two informants were interviewed by psychological autopsy, and life events were assessed with Paykel's Interview for Recent Life Events. Validities of integrated proxy data using six psychological autopsy information reconstruction methods were evaluated, with living subjects' self-reports used as gold-standard criteria. RESULTS: For all the life events, average value of Youden Indexes for proxy data by type C information reconstruction method (choosing positive value from two informants) was larger than other five methods'. For family life related events, proxy data by type 1st information reconstruction method were not significantly different from living subjects' self-reports (P = 0.828). For all other life events, proxy data by type C information reconstruction method were not significantly different from the gold-standard. CONCLUSIONS: Choosing positive value is a relatively better method for integrating dichotomous (positive vs. negative) proxy data from two informants in life event assessment in psychological autopsy, except for family life related events. In that case, using information provided by 1st informants (mainly family member) is recommended.


Asunto(s)
Familia/psicología , Entrevista Psicológica , Apoderado/psicología , Suicidio/psicología , Encuestas y Cuestionarios , Adolescente , Adulto , Estudios de Casos y Controles , China , Femenino , Humanos , Acontecimientos que Cambian la Vida , Masculino , Persona de Mediana Edad , Escalas de Valoración Psiquiátrica , Reproducibilidad de los Resultados , Suicidio/estadística & datos numéricos , Adulto Joven
11.
Org Biomol Chem ; 15(40): 8669-8679, 2017 Oct 18.
Artículo en Inglés | MEDLINE | ID: mdl-28990625

RESUMEN

N,N'-Dialkylbarbituric acids as cyclic malonamide donors were successfully used in the enantioselective Michael addition reaction of enones. Using cinchona alkaloid-based bifunctional squaramide as an organocatalyst, this Michael reaction of N,N'-di-tert-butylbarbituric acid with various enones features a highly enantioselective (91-99% ee) production of the corresponding optically active 5-substituted barbituric acid derivatives. The transformations of the Michael product for the barbituric acid structural unit were realized in two ways, deprotection to remove the N-tert-butyl group and alkylation to produce 5,5-disubstituted barbituric acid derivatives.


Asunto(s)
Barbitúricos/química , Alcaloides de Cinchona/química , Cetonas/química , Quinina/análogos & derivados , Barbitúricos/síntesis química , Catálisis , Conformación Molecular , Quinina/química , Estereoisomerismo
12.
J Clin Monit Comput ; 30(6): 807-820, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26392184

RESUMEN

Offline general-type models are widely used for patients' monitoring in intensive care units (ICUs), which are developed by using past collected datasets consisting of thousands of patients. However, these models may fail to adapt to the changing states of ICU patients. Thus, to be more robust and effective, the monitoring models should be adaptable to individual patients. A novel combination of just-in-time learning (JITL) and principal component analysis (PCA), referred to learning-type PCA (L-PCA), was proposed for adaptive online monitoring of patients in ICUs. JITL was used to gather the most relevant data samples for adaptive modeling of complex physiological processes. PCA was used to build an online individual-type model and calculate monitoring statistics, and then to judge whether the patient's status is normal or not. The adaptability of L-PCA lies in the usage of individual data and the continuous updating of the training dataset. Twelve subjects were selected from the Physiobank's Multi-parameter Intelligent Monitoring for Intensive Care II (MIMIC II) database, and five vital signs of each subject were chosen. The proposed method was compared with the traditional PCA and fast moving-window PCA (Fast MWPCA). The experimental results demonstrated that the fault detection rates respectively increased by 20 % and 47 % compared with PCA and Fast MWPCA. L-PCA is first introduced into ICU patients monitoring and achieves the best monitoring performance in terms of adaptability to changes in patient status and sensitivity for abnormality detection.


Asunto(s)
Cuidados Críticos/métodos , Unidades de Cuidados Intensivos , Monitoreo Fisiológico/instrumentación , Monitoreo Fisiológico/métodos , Adulto , Anciano , Anciano de 80 o más Años , Algoritmos , Femenino , Humanos , Pacientes Internos , Aprendizaje , Masculino , Persona de Mediana Edad , Modelos Estadísticos , Sistemas en Línea , Análisis de Componente Principal , Reproducibilidad de los Resultados , Procesamiento de Señales Asistido por Computador , Programas Informáticos
13.
Zhejiang Da Xue Xue Bao Yi Xue Ban ; 44(2): 189-96, 2015 03.
Artículo en Zh | MEDLINE | ID: mdl-26038139

RESUMEN

OBJECTIVE: To perform a systematic review between all-cause mortality and body mass index (BMI) in Asian adults. METHOD: Relevant prospective studies that reported the relative risks (RRs) of all-cause mortality for community-based adults in Asia were identified by a literature search.PubMed and CNKI electronic databases were searched from inception through September 30, 2014, with language restrictions of English and Chinese. Data were extracted by 1 reviewer and then reviewed by 3 independent reviewers. The overall effect of varied levels of BMI and all-cause mortality were then pooled and analyzed.Potential sources of heterogeneity were detected by stratification analyses and sensitivity analyses. Publication bias was detected by funnel plot, Egger's test and Begg's test. RESULTS: Seventeen studies met the inclusion criteria; these studies included 1 769 369 individuals with 104 888 deaths. Random-effects summary all-cause mortality RRs was calculated. With the use of a BMI (in kg/m²) of 18.5~22.9 as the reference, the summary RRs were 1.39(95% CI: 1.31~1.47) for BMI less than 18.5 kg/m² , 0.88 (95% CI: 0.85~0.92) for BMI of 23.0~29.9 kg/m² and 1.14 (95% CI: 1.05~1.23) for BMI more than 30.0 kg/m². The RRs tended to be higher when weight and height were self-reported rather than measured. The RRs were higher when papers were published before the year 2005 rather than after the year 2006. Also, the RRs were higher when the quality scores were higher. Potential sources of heterogeneity were gender, the method of obtaining weight and height, geography, publication year and quality scores. There was no publication bias (P>0.05) in this meta-analysis. CONCLUSION: There was an increased risk of all-cause mortality for those both at the lower and higher level of BMI in Asian adults.


Asunto(s)
Índice de Masa Corporal , Mortalidad , Adulto , Pueblo Asiatico , Humanos , Factores de Riesgo
14.
Opt Express ; 22(26): 31984-92, 2014 Dec 29.
Artículo en Inglés | MEDLINE | ID: mdl-25607166

RESUMEN

A Mach-Zehnder interferometer (MZI) based fiber axial micro-displacement sensor was proposed. The MZI was constructed by a bowknot-type taper (BTT) combining with a fiber core-offset between two single mode fibers (SMFs). The axial micro-displacement of the core offset is correlated with the MZI transmission spectrum and varied with the interferometer arm length. For the arm length L of 12, 18, 24 and 30 mm, the proposed sensors showed high sensitivity of -0.362 dB/µm, -0.385 dB/µm, -0.332 dB/µm and -0.235dB/µm, and temperature errors of -0.056 dB/°C, -0.036 dB/°C, -0.044 dB/°C, -0.048 dB/°C, respectively. The theoretical simulations of the energy distributions were also given. The obtained sensitivity of -0.385 dB/µm is about 150 times high than that of the current similar existing axial micro-displacement sensor.


Asunto(s)
Tecnología de Fibra Óptica/instrumentación , Interferometría/instrumentación , Modelos Teóricos , Refractometría/instrumentación , Transductores de Presión , Transductores , Simulación por Computador , Diseño Asistido por Computadora , Diseño de Equipo , Análisis de Falla de Equipo , Movimiento (Física) , Dispositivos Ópticos , Torque
15.
J Org Chem ; 79(23): 11759-67, 2014 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-25375832

RESUMEN

Asymmetric alkynylation of seven-membered cyclic imine dibenzo[b,f][1,4]oxazepines is successfully achieved by combining chiral phosphoric acid and Ag(I) catalysts. Various arylacetylenes, conjugated enynes, and terminal 1,3-diynes are good substrates for this reaction, and aliphatic hexyne is also a suitable donor at elevated temperature. Optimization of this approach has provided a facile method to synthesize optically active 11-substituted-10,11-dihydrodibenzo[b,f][1,4]oxazepine derivatives containing a carbon-carbon triple bond with 63-99% ee. Subsequent transformations of the carbon-carbon triple bond for the heterocyclic products have been disclosed.


Asunto(s)
Alquinos/química , Compuestos Heterocíclicos/síntesis química , Iminas/química , Oxazepinas/síntesis química , Ácidos Fosfóricos/química , Plata/química , Catálisis , Compuestos Heterocíclicos/química , Oxazepinas/química , Estereoisomerismo
16.
Org Biomol Chem ; 12(45): 9101-4, 2014 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-25313683

RESUMEN

A highly enantioselective direct Mannich reaction of methyl alkyl ketones with cyclic imines benzo[e][1,2,3]oxathiazine 2,2-dioxides, catalyzed by the combination of cinchona alkaloid derived primary amine and TFA, is disclosed. For unsymmetrical methyl alkyl ketones, it is favoured that specific regioselective addition to the imine substrates occurs at the less-substituted methyl group by steric control.


Asunto(s)
Iminas/química , Cetonas/química , Óxidos/química , Tiazinas/química , Catálisis , Ciclización , Estructura Molecular , Estereoisomerismo
17.
Appl Opt ; 53(17): 3706-11, 2014 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-24921136

RESUMEN

A hybrid circular subwavelength grating mirror is proposed and fabricated as a rear mirror in a fast axial flow CO2 laser system to generate azimuthally polarized beams (APBs). This grating mirror, with particular gold-covered ridges and nanopillar-stuffed grooves, performs wideband TE wave reflectivity and high polarization selectivity. It shows that the polarization selectivity mechanism lies in the gold ridge's high reflectivity to the TE wave and the lower TM wave reflectivity, which are the result of the mode leaking into substrate through the dielectric-like nanopillar layer. Finally, a high-quality 550 W APB is obtained in subsequent experiments, which provides potential applications in drilling and welding.

18.
J Clin Monit Comput ; 28(1): 13-26, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-23748601

RESUMEN

To simulate and evaluate the administration of anesthetic agents in the clinical setting, many pharmacology models have been proposed and validated, which play important roles for in silico testing of closed-loop control methods. However, to the authors' best knowledge, there is no anesthesia simulator incorporating closed-loop feedback control of anesthetic agent administration freely available and accessible to the public. Consequently, many necessary but time consuming procedures, such as selecting models from the available literatures and establishing new simulator algorithms, will be repeated by different researchers who intend to explore a novel control algorithm for closed-loop anesthesia. To address this issue, an enriched anesthesia simulator was devised in our laboratory and made freely available to the anesthesia community. This simulator was built by using MATLAB(®) (The MathWorks, Natick, MA). The GUI technology embedded in MATLAB was chosen as the tool to develop a human-machine interface. This simulator includes four types of anesthetic models, and all have been wildly used in closed-loop anesthesia studies. For each type of model, 24 virtual patients were created with significant diversity. In addition, the platform also provides a model identification module and a control method library. For the model identification module, the least square method and particle swarm optimization were presented. In the control method library, a proportional-integral-derivative control and a model predictive control were provided. Both the model identification module and the control method library are extensive and readily accessible for users to add user-defined functions. This simulator could be a benchmark-testing platform for closed-loop control of anesthesia, which is of great value and has significant development potential. For convenience, this simulator is termed as Wang's Simulator, which can be downloaded from http://www.AutomMed.org .


Asunto(s)
Anestesia por Circuito Cerrado/métodos , Simulación por Computador , Algoritmos , Atracurio/química , Peso Corporal , Gráficos por Computador , Femenino , Humanos , Isoflurano/química , Masculino , Sistemas Hombre-Máquina , Farmacología , Piperidinas/química , Propofol/química , Remifentanilo , Programas Informáticos , Interfaz Usuario-Computador
19.
Nanomaterials (Basel) ; 14(5)2024 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-38470770

RESUMEN

Conventional sandwich structure photoelectrochemical UV detectors cannot detect UV light below 300 nm due to UV filtering problems. In this work, we propose to place the electron collector inside the active material, thus avoiding the effect of electrodes on light absorption. We obtained a TiO2-nanotubes@Ti@quartz photoanode structure by precise treatment of a commercial Ti mesh by anodic oxidation. The structure can absorb any light in the near-UV band and has superior stability to other metal electrodes. The final encapsulated photoelectrochemical UV detectors exhibit good switching characteristics with a response time below 100 ms. The mechanism of the oxidation conditions on the photovoltaic performance of the device was investigated by the electrochemical impedance method, and we obtained the optimal synthesis conditions. Response tests under continuous spectroscopy confirm that the response range of the device is extended from 300-400 nm to 240-400 nm. This idea of a built-in collector is an effective way to extend the response range of a photoelectrochemical detector.

20.
ChemSusChem ; : e202400997, 2024 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-38923349

RESUMEN

The design and construction of highly efficient electrocatalysts for overall water splitting and urea electrolysis are significantly important for promoting energy conversion and realizing green hydrogen production. In this work, we constructed a multi-phase heterojunction through a simple hydrothermal and phosphorization process. The P-doped NiFe2O4 (P-NiFe2O4) nanoparticles were uniformly anchored on the bamboo-like N-doped carbon nanotubes (NCNTs) grown via a NiFe-alloy autocatalysis. The electronic structure and coordination environment of active species were optimized by the synergistic action of P doping, well-dispersed ultrafine NiFe2O4, and NCNTs matrix with good conductivity, enhancing their quantity and activity for electrocatalysis. Consequently, the P-NiFe2O4/NCNTs/NiFe exhibits excellent HER and OER activities with an overpotential of 111 and 266 mV at 10 mA cm-2 in 1 M KOH, respectively. The symmetrical overall water-splitting cell using P-NiFe2O4/NCNTs/NiFe as both anode and cathode delivers 10 mA cm-2 at a voltage of 1.604 V in 1 M KOH. Notably, the two-electrode cell requires a low voltage of 1.467 V to achieve a current density of 10 mA cm-2 in 1 M KOH solution with 0.6 M urea. This designed catalysts display outstanding reaction kinetics and catalytic stability. This work provides useful guidance for applying transition metal-based catalysts for hydrogen production.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA