Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 34
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
J Med Virol ; 96(2): e29470, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38362933

RESUMO

The 2022 multi-country mpox outbreak raised public concern globally. Self-isolation and informing close contacts after developing mpox-related symptoms are critical measures in controlling the outbreak. This study investigated behavioral intentions of self-isolation and informing close contacts after developing mpox-related symptoms and associated factors among young men who have sex with men (YMSM) aged 18-29 years in China. The cross-sectional study was conducted among 2493 YMSM in six provincial regions in China from September 10th to 30th, 2022. Descriptive and logistic analyses were applied, using the intentions of self-isolation and informing close contacts after developing mpox-related symptoms as binary outcomes. The mean age of the participants was 24.6 (SD = 2.9) years. The prevalence of having intentions of self-isolation and informing close contacts after developing mpox-related symptoms was 88.6% (95% CI: 87.3%-89.9%) and 84.9% (95% CI: 83.5%-86.3%). Participants who were employed (adjusted odds ratio (AOR) = 1.474, 95% CI: 1.035-2.097; AOR = 1.371, 95% CI:1.002, 1.876), had higher mpox knowledge scores (AOR = 1.474, 95% CI: 1.035-2.097; AOR = 1.371, 95% CI: 1.002-1.876), and had higher perceived threats of mpox (AOR = 1.079, 95% CI: 1.030-1.130; AOR = 1.045, 95% CI: 1.002-1.090) were more likely to intend to self-isolate and inform close contacts. Participants who had MSM in-person gatherings in the past 6 months were more likely to intend to self-isolate (AOR = 1.392, 95% CI: 1.066-1.208). Participants with higher depression scores (AOR = 0.968, 95% CI: 0.948-0.989) and self-stigma (AOR = 0.975, 95% CI: 0.954-0.997) were less likely to intend to self-isolate and inform close contacts, respectively. Self-isolation and informing close contacts when developing disease-related symptoms are acceptable measures in response to mpox in China. Strengthening targeted risk communication and self-efficacy, raising disease knowledge, providing mental support, and reducing stigma toward the affected community are warranted.


Assuntos
Infecções por HIV , Mpox , Minorias Sexuais e de Gênero , Masculino , Humanos , Adulto Jovem , Adulto , Homossexualidade Masculina , Estudos Transversais , Intenção , China/epidemiologia , Infecções por HIV/epidemiologia
2.
J Med Virol ; 95(8): e29057, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37635623

RESUMO

The mpox outbreak since 2022 had attacked the community of men who have sex with men (MSM) heavily. This large cross-sectional study investigated the levels and associated factors of mpox risk perception among young MSM (YMSM) aged 18-29 years in six provincial regions of China in September 2022. The participants were recruited via facility-based sampling. Mpox risk perception was measured by perceived susceptibility and perceived severity of mpox. Geodetector was used to measure stratified heterogeneity of mpox risk perception. Univariate and multivariable linear regressions were used to examine the factors associated with mpox risk perception. A total of 2493 participants were included with a mean age of 24.6 years. The proportion of perceiving a susceptibility of mpox under different scenarios ranged 3.7%-17.0% and that of perceiving a severity of mpox ranged 81.6%-83.2%. Stratified heterogeneity of perceived susceptibility, perceived severity, and overall perceived risk of mpox were observed in several characteristics such as study sites, monthly income, risk behaviors, and psychosocial factors. Multivariable regression showed the level of mpox risk perception was positively associated with having in-person gathering activities (ba = 0.457, 95% CI: 0.208, 0.705), history of HIV infection (ba = 0.431, 95% CI: 0.028, 0.834), depressive symptoms (ba = 0.069, 95% CI: 0.049, 0.090), and self-stigma to MSM identity (ba = 0.047, 95% CI: 0.024, 0.071). The Chinese YMSM showed a high level of perceived severity of mpox but a low level of perceived susceptibility. It is warranted to strengthen targeted risk communication of mpox, develop comprehensive and unstigmatized health messages, and provide mental health support for YMSM.


Assuntos
Infecções por HIV , Homossexualidade Masculina , Mpox , Minorias Sexuais e de Gênero , Adulto , Humanos , Masculino , Adulto Jovem , Estudos Transversais , População do Leste Asiático , Infecções por HIV/epidemiologia , Percepção , Risco , Adolescente
3.
Soft Matter ; 19(24): 4401-4431, 2023 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-37309746

RESUMO

PVDF-based polymers with polar covalent bonds are next-generation dielectric materials for electric energy storage applications. Several types of PVDF-based polymers, such as homopolymers, copolymers, terpolymers and tetrapolymers, were synthesized by radical addition reactions, controlled radical polymerizations, chemical modifications or reduction with the monomers of vinylidene fluoride (VDF), tetrafluoroethylene (TFE), trifluoroethylene (TrFE), hexafluoropropylene (HFP) and chlorotrifluoroethylene (CTFE). Owing to rich molecular structures and complicated crystal structures, PVDF-based dielectric polymers can show versatile dielectric polarization properties, including normal ferroelectrics, relaxor ferroelectrics, anti-ferroelectrics and linear dielectrics, which are beneficial for designing polymer films with high capacity and high charge-discharge efficiency for capacitor applications. Furthermore, to satisfy the requirements of practical high-capacity capacitors, the polymer nanocomposite method is another promising strategy to achieve high-capacitance dielectric materials by the addition of high-dielectric ceramic nanoparticles, moderate-dielectric nanoparticles (MgO, and Al2O3), high-insulation nanosheets (BN), etc. It is concluded with the current problems and future perspectives of interfacial engineering, such as core-shell strategies and hierarchical interfaces in polymer-based composite dielectrics for high-energy-density capacitor applications. In addition, an in-depth understanding of the roles of interfaces on the dielectric properties of nanocomposites can be achieved by indirect analysis techniques (theoretical simulation) and direct analysis techniques (scanning probe microscopy). Our systematic discussions on molecular, crystal and interfacial structures provide guidance for designing fluoropolymer-based nanocomposites for high-performance capacitor applications.

4.
Opt Express ; 27(2): 774-782, 2019 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-30696158

RESUMO

We apply the antenna coherence theory in order to evaluate characteristic behavior of phase-coherent VCSEL arrays. Large 19-element phase-locked VCSEL arrays with a near-diffraction-limited beam were firstly realized using proton implantation technology. The central lobe intensity is about four times that of side lobes in far-field patterns. The angular full width at half maximum (FWHM) of the far field lobes is only 1.42 degrees. A good matching between theory and experiment opens new perspectives for optimizing devices.

5.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 31(4): 899-904, 2014 Aug.
Artigo em Zh | MEDLINE | ID: mdl-25464810

RESUMO

With the progresses of the research on "Digital Human", more and more information has been needed for the setting up of the three-dimensional digital models of human organs. In the present paper, based on the method of block mapping with a normal-style bump mapping method, we normalized the vector of the surface of the models, computed offset of the texture coordinates and added to them. The projection of the coordinates to the tangential space complemented the disturbance to the vector of models' surface. The method was proposed with bump texture mapping on the surface of the biological models of organs to improve the impression of the visualization of the organ models and to enhance the sense of reality of the models.


Assuntos
Modelos Anatômicos , Modelos Biológicos , Humanos
6.
Sheng Wu Gong Cheng Xue Bao ; 40(6): 1924-1934, 2024 Jun 25.
Artigo em Zh | MEDLINE | ID: mdl-38914501

RESUMO

Valencene, a high-value sesquiterpene with a citrus aroma, is widely employed in the food and cosmetic fields and the industrial synthesis of nootkatone. In this study, 16 genomic loci in the intergenic regions (IGRs) of Saccharomyces cerevisiae were identified. A Ypet expression cassette was successfully integrated into various genomic loci by CRISPR-Cas9, with an impressive integration success rate of 87.50% and exhibiting expression variations of up to 1.91-fold depending on the insertion site. The study demonstrates that the positional effect exhibits relative stability in gene expression, and is essentially unaffected by changes in promoters and reporter genes. Furthermore, a high-expression element combination, PTDH3-TPRC1, was selected. The iterative integration of the valencene synthase gene VSm from Callitropsis nootkatensis at the selected loci increased the valencene yield to 254.67 mg/L. Overexpression of key genes tHMG1-ERG20 with multiple copies increased the valencene yield by 93.49%. The engineered strain L-13 achieved the valencene yield of 9 530.18 mg/L by two-stage fed-batch fermentation in a 3 L fermenter. This yield represents a nearly 100-fold increase compared with that of the starting strain, highlighting the significant potential of the screened genomic loci in optimizing valencene production.


Assuntos
Sistemas CRISPR-Cas , Saccharomyces cerevisiae , Sesquiterpenos , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Sesquiterpenos/metabolismo , Engenharia Metabólica/métodos , Sesquiterpenos Policíclicos/metabolismo
7.
Food Chem ; 439: 138176, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38091790

RESUMO

Steamed green tea has a long history and unique aroma, but little is known about its key aroma components. In this study, 173 volatiles in steamed green tea were identified using solvent-assisted flavor evaporation and headspace-solid phase microextraction plus two chromatographic columns of different polarities. Aroma extract dilution analysis revealed 48 highly aroma-active compounds with flavor dilution factors 64-1024. Internal standards were used to calculate odorant active value (OAV), and 11 OAV > 1 key aroma compounds were determined. Omission test identified eight substances, including dimethyl sulfide, (E)-ß-ionone, cis-jasmone, linalool, nonanal, heptanal, isovaleraldehyde and (Z)-3-hexenol, as the key aroma active compounds of steamed green tea. With the increase of withering degree, the content of these substances increased first and then decreased except for heptanal and cis-jasmone. Moreover, the water content of 62 % was suggested to be an appropriate withering degree during the processing of steamed green tea.


Assuntos
Odorantes , Compostos Orgânicos Voláteis , Odorantes/análise , Chá/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Vapor , Compostos Orgânicos Voláteis/análise
8.
Neural Netw ; 170: 176-189, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37989039

RESUMO

Knowledge distillation (KD) is a widely adopted model compression technique for improving the performance of compact student models, by utilizing the "dark knowledge" of a large teacher model. However, previous studies have not adequately investigated the effectiveness of supervision from the teacher model, and overconfident predictions in the student model may degrade its performance. In this work, we propose a novel framework, Teacher-Student Complementary Sample Contrastive Distillation (TSCSCD), that alleviate these challenges. TSCSCD consists of three key components: Contrastive Sample Hardness (CSH), Supervision Signal Correction (SSC), and Student Self-Learning (SSL). Specifically, CSH evaluates the teacher's supervision for each sample by comparing the predictions of two compact models, one distilled from the teacher and the other trained from scratch. SSC corrects weak supervision according to CSH, while SSL employs integrated learning among multi-classifiers to regularize overconfident predictions. Extensive experiments on four real-world datasets demonstrate that TSCSCD outperforms recent state-of-the-art knowledge distillation techniques.


Assuntos
Compressão de Dados , Humanos , Conhecimento , Aprendizagem , Estudantes
9.
Food Chem ; 438: 138062, 2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-38064793

RESUMO

This study used samples processed with an innovative manufacturing process to explore the dynamic changes of large-leaf yellow tea (LYT) in color, aroma, and taste substances, and the quality components were most significantly affected in the stages of first pile-yellowing (FP) and over-fired drying (TD). In this process, the moisture and temperature conditions caused chlorophyll degradation, Maillard reactions, caramelization reactions, and isomerization of phenolic substances, forming the quality of LYT. Specifically, chlorophyll degradation favored the formation of color quality; the taste quality was determined by the content of soluble sugars, amino acids, catechins, etc.; the aroma quality was dependent on the content changes of alcohols and aldehydes, as well as the increase of sweet and roasting aroma substances in the third drying stage. Additionally, twelve key aroma components, including linalool, (E)-ß-ionone, 2,3-diethyl-5-methyl-pyrazine, etc., were identified as contributors to revealing LYT rice crust-like and sweet aroma formation mechanism.


Assuntos
Camellia sinensis , Compostos Orgânicos Voláteis , Odorantes/análise , Chá/química , Camellia sinensis/química , Paladar , Cromatografia Gasosa-Espectrometria de Massas , Compostos Orgânicos Voláteis/análise , Folhas de Planta/química , Clorofila/análise
10.
Food Chem ; 438: 137837, 2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-37979270

RESUMO

Acidification of aroma-enhanced black tea during storage was studied. UPLC-Q-TOF/MS (Ultra Performance Liquid Chromatography and Quadrupole-Time of Flight Mass Spectrometer) and HPLC (High-Performance Liquid Chromatography) analysis of non-volatile substances and organic acids revealed a decrease of soluble sugars and amino acids in aroma-enhanced black tea, while an increase in organic acids such as oxalic acid, malic acid and quinic acid. Further in vitro experiments indicated that the acidification of aroma-enhanced tea during storage can be attributed to decomposition of sugars and amino acids by heating, oxidation of aromatic aldehydes. Meanwhile, the amino acids, catechins, soluble sugars and flavonoids that constitute the taste of black tea are further reduced, changing the taste composition of tea infusion and further increasing its acidity. This study revealed the reasons for black tea acidification during aroma enhancement and storage and provided a theoretical basis for improving black tea quality.


Assuntos
Camellia sinensis , Compostos Orgânicos Voláteis , Chá/química , Odorantes/análise , Temperatura , Camellia sinensis/química , Aminoácidos , Aminas/análise , Açúcares , Concentração de Íons de Hidrogênio , Compostos Orgânicos Voláteis/análise
11.
China CDC Wkly ; 6(14): 294-299, 2024 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-38634100

RESUMO

Introduction: To examine the recent trends in child injury mortality in China. Methods: Injury mortality data of 2010-2021 for children and adolescents aged 0-19 years were from the China Health Statistics Yearbook. Injury mortality disparities across urban vs. rural locations, gender, and age groups were scrutinized. Annual percent change (APC), average annual percent change (AAPC), and their 95% confidence intervals (95% CI) were estiamted usimg Joinpoint regression models. Results: The age-standardized injury mortality significantly dropped from 21.87 to 9.41 per 100,000 population among children and youth aged 0-19 years during 2010-2021, with an AAPC of -6.7% (95% CI: -8.2%, -5.2%). The urban-rural disparity and gender gap in injury mortality reduced gradually. In 2021, drowning and road traffic crashes were the top two causes of child injury deaths, explaing 31.1% and 27.9% of total injury deaths, respectively. Suffocation accounted for 62.3% of injury deaths among infants younger than a year. Alarmingly, the suicide mortality rate rose from 2.16 to 3.42 per 100,000 population between 2010 and 2021 among teenagers aged 15-19 years. Subgroup analyses yielded similar results. Conclusions: During 2010-2021, the injury mortality decreased significantly among Chinese children and adolescents, and the responding urban-rural disparities narrowed.

12.
JMIR Public Health Surveill ; 10: e47165, 2024 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-38502181

RESUMO

BACKGROUND: The worldwide human monkeypox (mpox) outbreak in 2022 mainly affected men who have sex with men (MSM). In China, young men who have sex with men (YMSM) were at a potential high risk of mpox infection due to their sexual activeness and the eased COVID-19 restrictions at the end of 2022. OBJECTIVE: This study aimed to investigate the behavioral intention of receiving mpox vaccination and undergoing mpox testing in 4 different scenarios and explore their associations with background and behavioral theory-related factors among Chinese YMSM. METHODS: An online cross-sectional survey was conducted among YMSM aged 18-29 years from 6 representative provinces of China in September 2022. Participants recruited (recruitment rate=2918/4342, 67.2%) were asked to self-administer an anonymous questionnaire designed based on prior knowledge about mpox and classic health behavior theories. Data on the participants' background, mpox knowledge and cognition, mpox vaccination and testing cognition, and the behavioral intention of receiving mpox vaccination and undergoing mpox testing were collected. Descriptive analysis and univariate and multivariate linear regressions were performed. Geodetector was used to measure the stratified heterogeneity of behavioral intention. RESULTS: A total of 2493 YMSM with a mean age of 24.6 (SD 2.9) years were included. The prevalence of having a behavioral intention of receiving mpox vaccination ranged from 66.2% to 88.4% by scenario, varying in epidemic status and cost. The prevalence of having an mpox testing intention was above 90% in all scenarios regardless of the presence of symptoms and the cost. The positive factors related to vaccination intention included mpox knowledge (ba=0.060, 95% CI 0.016-0.103), perceived susceptibility of mpox (ba=0.091, 95% CI 0.035-0.146), perceived severity of mpox (ba=0.230, 95% CI 0.164-0.296), emotional distress caused by mpox (ba=0.270, 95% CI 0.160-0.380), perceived benefits of mpox vaccination (ba=0.455, 95% CI 0.411-0.498), self-efficacy of mpox vaccination (ba=0.586, 95% CI 0.504-0.668), and having 1 male sex partner (ba=0.452, 95% CI 0.098-0.806), while the negative factor was perceived barriers to vaccination (ba=-0.056, 95% CI -0.090 to -0.022). The positive factors related to testing intention were perceived severity of mpox (ba=0.283, 95% CI 0.241-0.325), perceived benefits of mpox testing (ba=0.679, 95% CI 0.636-0.721), self-efficacy of mpox testing (ba=0.195, 95% CI 0.146-0.245), having 1 male sex partner (ba=0.290, 95% CI 0.070-0.510), and having in-person gatherings with MSM (ba=0.219, 95% CI 0.072-0.366), while the negative factor was emotional distress caused by mpox (ba=-0.069, 95% CI -0.137 to -0.001). CONCLUSIONS: Among Chinese YMSM, the intention of undergoing mpox testing is optimal, while the mpox vaccination intention has room for improvement. A future national response should raise YMSM's mpox knowledge, disseminate updated information about mpox and preventive measures, improve preventive service accessibility and privacy, and provide advice on positively coping with the associated emotional distress.


Assuntos
Técnicas de Laboratório Clínico , Mpox , Minorias Sexuais e de Gênero , Vacina Antivariólica , Masculino , Humanos , Adulto Jovem , Adulto , Homossexualidade Masculina , Estudos Transversais , Intenção , China/epidemiologia
13.
Artigo em Inglês | MEDLINE | ID: mdl-37590116

RESUMO

Recently, many works have been proposed to utilize the neural radiance field for novel view synthesis of human performers. However, most of these methods require hours of training, making them difficult for practical use. To address this challenging problem, we propose IntrinsicNGP, which can train from scratch and achieve high-fidelity results in few minutes with videos of a human performer. To achieve this target, we introduce a continuous and optimizable intrinsic coordinate rather than the original explicit Euclidean coordinate in the hash encoding module of instant-NGP. With this novel intrinsic coordinate, IntrinsicNGP can aggregate inter-frame information for dynamic objects with the help of proxy geometry shapes. Moreover, the results trained with the given rough geometry shapes can be further refined with an optimizable offset field based on the intrinsic coordinate. Extensive experimental results on several datasets demonstrate the effectiveness and efficiency of IntrinsicNGP. We also illustrate our approach's ability to edit the shape of reconstructed subjects.

14.
Sci Rep ; 13(1): 7012, 2023 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-37117242

RESUMO

As an important component of the machining system, the influence of fixtures on the machining deformation of the workpiece cannot be ignored. By controlling the clamping force during the machining process is an effective means to suppress or improve the machining deformation. However, due to the dynamic coupling of part geometry, clamping method, manufacturing process and time-varying cutting forces, it is difficult to obtain accurate clamping forces, which hinders the realization of fixture-based deformation control. In this paper, the variation of clamping force is considered as the response of the joint action of cutting force and other working conditions in spatial and temporal terms, and a clamping force prediction method based on deep spatio-temporal network is proposed. The part geometry model is first parameterized based on voxels, after which the cutting forces are dynamically correlated with the clamping forces in spatial and temporal terms. Then, a convolutional network was designed to capture the spatial correlation between the working conditions such as cutting force and clamping force, and a gated recurrent cell network to capture the temporal correlation to predict the clamping force during machining. Finally, an experiment of milling a cylindrical thin-walled part illustrates the effectiveness of the proposed method.

15.
J Agric Food Chem ; 71(48): 18919-18927, 2023 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-37991146

RESUMO

Nootkatone is a type of valuable sesquiterpene that is widely used in food, cosmetics, fragrance, and other fields. The industry is faced with a major challenge due to the high expenses associated with plant-extracted nootkatone. We have developed a fermentation process for valencene production using seaweed hydrolysate as a carbon source via engineered Saccharomyces cerevisiae. Reduced-pressure distillation purified valencene was used as a substrate, and a yeast strain carrying HPO/AtCPR1 and ADH genes was constructed for whole-cell catalysis. After biotransformation at 25 °C for 3 h, a high yield of 73% for nootkatone production was obtained. Further, simple rotary evaporation was used to obtain nootkatone with a high purity of 97.4%. Mosquito-repellent testing showed that 1% nootkatone has a mosquito-repellent effect lasting up to 6 h, which is comparable to the 20% N,N-diethyl-meta-toluamide (DEET) effect. This study provided practical experience for developing third-generation biomass resources, generating new ideas for green manufacturing of valuable chemical products, and serving as a reference for creating efficient and eco-friendly mosquito repellents.


Assuntos
Repelentes de Insetos , Inseticidas , Sesquiterpenos , Sesquiterpenos Policíclicos , Sesquiterpenos/metabolismo , DEET , Verduras/metabolismo , Saccharomyces cerevisiae/metabolismo
16.
Food Chem X ; 19: 100809, 2023 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-37780350

RESUMO

Nine tea cultivars planted in Enshi were selected and processed into "Lichuan black tea". Sensory evaluation showed that cultivar had the greatest influence on taste and aroma quality, including sweetness, umami and concentration of taste, as well as sweet and floral fragrances of aroma. The non-volatile and volatile components were identified by UPLC-Q-TOF/MS and GC-MS, and PCA analysis showed good separation between cultivars, which could cause the difference in quality. Baiyaqilan, Meizhan and Echa 10 had a floral aroma, with obvious difference in their aromatic composition from other cultivars. Moreover, Echa 10 also had a strong sweet aroma. The key aroma components in Echa 10 (with the largest cultivation area) were further investigated by GC-O-MS combined with odor activity value (OAV) analysis, included ß-damascenone, phenylethylaldehyde, nonenal, geraniol, linalool, jasmonone, (E)-2-nonenal, ß-cyclocitral, (E)-ß-ocimene, methyl salicylate, ß-ionone, 2,6,10,10-tetramethyl-1-oxaspiro[4.5]dec-6-ene, citral, ß-myrcene, nerol, phenethyl alcohol, benzaldehyde, hexanal, nonanoic acid, and jasmin lactone.

17.
Nanoscale ; 16(1): 180-187, 2023 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-37999642

RESUMO

To meet the strong demand for high-level encryption security, several efforts have been focused on developing new encryption techniques with high density and data security. Herein we employed a template-free electron beam lithography (EBL) technique to write various nanopatterns on poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CTFE)) films and applied it to electron-beam/electric multiplexing memory. Furthermore, electron beams can arbitrarily tailor down the domain structure evolutions and dipole directions, as proved by a combination of AFM-IR and PFM. Finally, our devices could function concurrently as an electron-beam write-only-memory (EB-WOM) and FeRAM, where the information could be encoded with the metastable phase evolutions from the ferroelectric phase to the paraelectric phase and variable bi-level ferroelectric signals. Our systematic study provides an inspiring idea for the design of information encryption devices with high-security requirements in flexible electronic fields.

18.
J Agric Food Chem ; 71(40): 14706-14719, 2023 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-37752697

RESUMO

Fermentation is the key technology for black tea aroma formation. The key aroma substances of black tea at different fermentation stages (unfermented (WDY), underfermented (F1H), fully fermented (F4H), and overfermented (F8H)) were characterized by the methodology of Sensomics. Aroma extract dilution analysis was performed on volatile fractions extracted by using solvent-assisted flavor evaporation and solid-phase microextraction, yielding 93 odor-active areas. Internal standard method plus stable isotope dilution analysis was used for quantitative analysis. The omission experiment identified 23 aroma substances. Further reduction and addition experiments revealed phenylacetaldehyde, (E,E)-2,4-heptadienal, geraniol, linalool, ß-damascenone, 2-methylbutyraldehyde, dimethyl sulfide, and isovaleraldehyde with odor activity values (OAV) > 100 as the characteristic aroma components of F4H and also as the main contributors to aroma differences between different fermentation degrees. The green odor of (E,E)-2,4-heptadienal was highlighted in WDY and F1H relative to that in F4H due to the lower contribution of phenylacetaldehyde and ß-damascenone in the former two samples. Additionally, excessive OAV increase of fatty aldehydes in F8H masked its similar floral and fruity aroma.

19.
Food Chem X ; 18: 100730, 2023 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-37397208

RESUMO

This study delved into the aroma characteristics of "Qingxiang" oolong tea, analyzing six different cultivars and their processing modes. The findings showed that both cultivars and processing modes have a significant impact on the oolong tea aroma system. The study identified 18 terpenoid volatiles (VTs), 11 amino-acid-derived volatiles (AADVs), 15 fatty-acid-derived volatiles (FADVs), 3 carotenoid-derived volatiles (CDVs), and 10 other compounds in oolong tea that differentiate it from green and black tea. The turn-over stage was found to be the primary processing stage for oolong tea aroma formation. Molecular sensory analysis revealed that the "fresh" odor attribute is the basis for its aroma, while "floral and fruity" fragrances are its aroma characteristics. The perception of oolong tea as "fresh" and "floral and fruity" is influenced by the interactions of its aroma components. These findings provide a new basis for breed improvement and process enhancement in oolong tea production.

20.
Sci Rep ; 12(1): 14574, 2022 08 26.
Artigo em Inglês | MEDLINE | ID: mdl-36028636

RESUMO

Evaluation of tool wear is vital in manufacturing system, since early detections on worn-out condition can ensure workpiece quality, improve machining efficiency. With the development of intelligent manufacturing, tool wear prediction technology plays an increasingly important role. However, traditional tool wear prediction methods rely on experience and knowledge of experts and are labor-extensive. Deep learning provides an effective way to extract features of raw data and establish the mapping relationship between features and targets automatically. In this paper, a new local-feature and global-dependency based tool wear prediction method is proposed. It is a hybrid approach combining manual features with automatic features. Firstly, an enhanced CNN network is designed and applied on the transformed wavelet scalogram to learn the local single-scale specific features and multi-scale correlation features automatically. Secondly, sequence of local feature vectors combining manual features with automatic features are fed into multi-layer LSTM step by step for the global dependency. A fully connected layer is then trained to predict tool wear. Finally, two statistics are proposed to illustrate the overall prediction performance and generalization ability of the model. An experiment illustrates the effectiveness of our proposed method under multiple working conditions.


Assuntos
Aprendizado Profundo , Redes Neurais de Computação , Tecnologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA