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1.
Neurotherapeutics ; 21(1): e00294, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38241163

RESUMO

RICAMIS (ClinicalTrials.gov Identifier: NCT03740971) trial has demonstrated efficacy of remote ischemic conditioning (RIC) in acute ischemic stroke, but whether baseline NIHSS score can affect outcomes in stroke remains unclear. We conducted a post hoc analysis of RICAMIS to investigate the issue. Patients included in RICAMIS were divided into three groups based on baseline NIHSS score. The primary outcome was excellent functional outcome at 90 days, defined as mRS score of 0-1. Compared with patients receiving usual care, we investigated association of RIC effect with outcomes in each group and interaction between RIC effect and stroke severity. Among 1776 patients, 1255 were assigned into NIHSS score 6-8 group, 402 into NIHSS score 9-12 group, and 119 into NIHSS score 13-16 group. A higher proportion of primary outcome was found associated with RIC in NIHSS score 9-12 group (adjusted risk difference [RD], 14.6 â€‹%; 95 â€‹% CI, 5.0 â€‹%-24.2 â€‹%; P â€‹= â€‹0.003), but no significant association was found in NIHSS score 6-8 group (adjusted RD, 2.3 â€‹%; 95 â€‹% CI, -2.5 â€‹%-7.2 â€‹%; P â€‹= â€‹0.34), or in NIHSS score 13-16 group (adjusted RD, 9.7 â€‹%; 95 â€‹% CI, -7.5 â€‹%-26.9 â€‹%; P â€‹= â€‹0.27). There was a significant interaction between RIC effect and stroke severity when analysis was performed between NIHSS score 6-8 and 9-12 groups (P â€‹= â€‹0.04), but not between NIHSS score 9-12 and 13-16 groups (P â€‹= â€‹0.57). Current study firstly reported patients with NIHSS score 9-12 may get more benefit from RIC after stroke with respect to excellent functional outcome at 90 days.


Assuntos
Isquemia Encefálica , AVC Isquêmico , Acidente Vascular Cerebral , Humanos , AVC Isquêmico/terapia , Isquemia Encefálica/terapia , Isquemia Encefálica/complicações , Acidente Vascular Cerebral/terapia , Acidente Vascular Cerebral/complicações , Resultado do Tratamento
2.
Spectrochim Acta A Mol Biomol Spectrosc ; 310: 123914, 2024 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-38266600

RESUMO

Metal nanostructure arrays with large amounts of nano-gaps are important for surface enhanced Raman scattering applications, though the fabrications of such nanostructures are difficult due to the complex and multiple synthetic steps. In this research, we report silver nanostructure array patterns (SNAPs) on silicon wafer, which is fabricated with semiconductor manufacturing technology, Cu2O electrochemistry deposition, and Ag In-situ oxidation-reduction growth. Benefiting from the dense and uniform distribution of Ag nanowires, the fabricated SNAPs demonstrate a very strong and uniform surface-enhanced Raman scattering (SERS) effect. The efficiency of SNAPs was investigated by using rhodamine 6G (R6G) dye as an analyte molecule. The results show that the minimum detectable concentration of R6G can reach as low as 10-11 M, and the Raman signals in the random region show good signal homogeneity with a low relative standard deviation (RSD) of 4.77 %. These results indicate that the SNAPs perform a great sensitivity and uniformity as a SERS substrate. Furthermore, we used the SNAPs substrate to detect antibiotic sulfadiazine. The main peaks in sulfadiazine Raman and vibration modes assignments were obtained and the quantitative analysis model was established by principal component analysis (PCA). The detection and application results of sulfadiazine indicate that the SNAPs substrate can be applied for trace detection of antibiotics. In addition, we have cited the application of the SNAPs substrate in anti-counterfeiting labels. These practical applications demonstrate that the fabricated SNAPs can potentially provide a way to develop low-cost SERS platforms for environmental detections, biomedicine analysis, and commodities anti-counterfeiting.

3.
Sci Rep ; 13(1): 20652, 2023 11 24.
Artigo em Inglês | MEDLINE | ID: mdl-38001235

RESUMO

Age and sex have effect on atherosclerosis. This study aimed to investigate their effect on non-stenotic intracranial atherosclerotic plaque (NIAP) in embolic stroke of undetermined source (ESUS) using high-resolution magnetic resonance imaging (HR-MRI). We retrospectively recruited consecutive ESUS patients who underwent intracranial HR-MRI to assess the plaque characteristics (remodeling index [RI], plaque burden [PB], fibrous cap [FC], discontinuity of plaque surface [DPS], intraplaque hemorrhage [IPH] and complicated plaque [CP]). We divided patients into three groups (< 60 years, 60-74 years, ≥ 75 years). 155 patients with ipsilateral NIAP were found from 243 ESUS patients, with 106 men (68.39%) and 49 women (31.61%). In total population or age group under 60 years, there were no significant differences in plaque characteristics between men and women (all p > 0.05). In age group of 60-74 years, men were associated with higher PB (66.27 ± 9.17% vs 60.91 ± 8.86%, p = 0.017) and RI (1.174 vs 1.156, p = 0.019), higher prevalence of DPS (82.50% vs 60.00%, p = 0.036) and complicated plaque (85.00% vs 63.33%, p = 0.036). For subjects ≥ 75 years old, PB were significantly higher in twomen vs men (68.85 ± 6.14% vs 62.62 ± 7.36%, p = 0.040). In addition, the probability for PBupper (≥ median PB), RIupper (≥ median RI) and vulnerable plaque increased as age increased, and its predictive power for index ESUS was higher in men than women. This study identified age-dependent sex differences in NIAP characteristics of ESUS patients, which will help us clarify their etiology.


Assuntos
AVC Embólico , Placa Aterosclerótica , Acidente Vascular Cerebral , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Idoso , Acidente Vascular Cerebral/complicações , Estudos Retrospectivos , Caracteres Sexuais , Placa Aterosclerótica/diagnóstico por imagem , Placa Aterosclerótica/complicações , Constrição Patológica/complicações
4.
Sci Rep ; 13(1): 17017, 2023 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-37813922

RESUMO

To evaluate the association of intracranial non-stenotic atherosclerotic plaque with cerebral small vessel disease (CSVD) imaging markers in a CSVD population using 3.0 T high-resolution magnetic resonance imaging (HRMRI), which was validated in embolic stroke of undetermined source (ESUS) cohort. We retrospectively recruited consecutive patients who were diagnosed with CSVD or ESUS from January 2015 to December 2019. All patients underwent intracranial HRMRI to assess intracranial non-stenotic atherosclerotic plaques. Baseline and imaging data were collected and were measured among all patients. Among 153 patients with CSVD, there were 59 with intracranial atherosclerotic plaque (IAP) and 94 with non-IAP, including 36 with intracranial atherosclerotic complicated plaque (IACP). Among 227 ESUS patients, there were 155 with IAP and 72 with non-IAP, including 127 with IACP. In the CSVD population, we found that: (1) CSVD burden was associated with IAP (p = 0.036) and IACP (p = 0.008); (2) IAP was associated with white matter hyperintensity (51% vs. 34%; P = 0.039), and IACP was associated with lacunes (69% vs. 35%; P = 0.009) and enlarge perivascular space (69% vs. 39%; P = 0.022). A similar association of CSVD imaging markers with IAP or IACP was found in the ESUS population. Furthermore, the association of unilateral IAP or IACP with CSVD imaging markers of ipsilateral hemisphere was identified in the two cohorts. This is the first report that intracranial non-stenotic atherosclerotic plaque, especially complicated plaque, is closely associated with CSVD imaging markers, which provide further evidence for the association of large artery atherosclerosis with CSVD.


Assuntos
Doenças de Pequenos Vasos Cerebrais , Arteriosclerose Intracraniana , Placa Aterosclerótica , Acidente Vascular Cerebral , Humanos , Placa Aterosclerótica/complicações , Placa Aterosclerótica/diagnóstico por imagem , Estudos Retrospectivos , Imageamento por Ressonância Magnética , Doenças de Pequenos Vasos Cerebrais/complicações , Doenças de Pequenos Vasos Cerebrais/diagnóstico por imagem , Arteriosclerose Intracraniana/complicações , Arteriosclerose Intracraniana/diagnóstico por imagem , Acidente Vascular Cerebral/complicações
5.
Stroke Vasc Neurol ; 8(5): 387-398, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-36914215

RESUMO

OBJECTIVE: To determine the characteristics of intracranial plaque proximal to large vessel occlusion (LVO) in stroke patients without major-risk cardioembolic source using 3.0 T high-resolution MRI (HR-MRI). METHODS: We retrospectively enrolled eligible patients from January 2015 to July 2021. The multidimensional parameters of plaque such as remodelling index (RI), plaque burden (PB), percentage lipid-rich necrotic core (%LRNC), presence of discontinuity of plaque surface (DPS), fibrous cap rupture, intraplaque haemorrhage and complicated plaque were evaluated by HR-MRI. RESULTS: Among 279 stroke patients, intracranial plaque proximal to LVO was more prevalent in the ipsilateral versus contralateral side to stroke (75.6% vs 58.8%, p<0.001). The larger PB (p<0.001), RI (p<0.001) and %LRNC (p=0.001), the higher prevalence of DPS (61.1% vs 50.6%, p=0.041) and complicated plaque (63.0% vs 50.6%, p=0.016) were observed in the plaque ipsilateral versus contralateral to stroke. Logistic analysis showed that RI and PB were positively associated with an ischaemic stroke (RI: crude OR: 1.303, 95% CI 1.072 to 1.584, p=0.008; PB: crude OR: 1.677, 95% CI 1.381 to 2.037, p<0.001). In subgroup with <50% stenotic plaque, the greater PB, RI, %LRNC and the presence of complicated plaque were more closely related to stroke, which was not evident in subgroup with ≥50% stenotic plaque. CONCLUSION: This is the first study to report the characteristics of intracranial plaque proximal to LVO in non-cardioembolic stroke. It provides potential evidence to support different aetiological roles of <50% stenotic vs ≥50% stenotic intracranial plaque in this population.


Assuntos
Isquemia Encefálica , Placa Aterosclerótica , Acidente Vascular Cerebral , Humanos , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/epidemiologia , Isquemia Encefálica/diagnóstico por imagem , Isquemia Encefálica/epidemiologia , Isquemia Encefálica/etiologia , Estudos Retrospectivos , Imageamento por Ressonância Magnética/efeitos adversos , Imageamento por Ressonância Magnética/métodos , Placa Aterosclerótica/complicações
6.
Eur J Neurol ; 30(3): 648-658, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36448742

RESUMO

BACKGROUND AND PURPOSE: The association between nonstenotic plaque at the petrous internal carotid artery (ICA) and embolic stroke of undetermined source (ESUS) remains unknown. We aimed to test the hypothesis that the presence of a larger build-up of petrous plaque is more prevalent in the ipsilateral versus the contralateral side among ESUS patients without plaque in the intracranial and proximal ICA. METHODS: From a total of 243 patients with ESUS and 160 patients with small-vessel disease (SVD) without proximal ICA plaque, we enrolled 88 ESUS and 103 SVD patients without ipsilateral nonstenotic intracranial and proximal ICA plaque in the present study. Targeting the petrous segment of the ICA on two sides, plaque burden including plaque thickness, lumen area, vessel area, wall area, and percentage of luminal stenosis, and composition features (presence/absence of the ruptured fibrous cap, ulcer plaque, thrombus, discontinuity of plaque surface [DPS], intraplaque hemorrhage and complicated plaque) were assessed by high-resolution magnetic resonance imaging. RESULTS: We found a higher prevalence of petrous plaque thickness ≥3.5 mm ipsilateral versus contralateral to the stroke (25/88 [28.4%] vs. 12/88 [13.6%], odds ratio [OR] 3.60, 95% confidence interval [CI] 1.34-9.70), but this imbalance was not seen in SVD. In patients with plaque thickness ≥3.5 mm, the presence of DPS (OR 4.05, 95% CI 1.11-14.78) and complicated plaque (OR 5.00, 95% CI 1.10-22.82) was more closely related to an index ESUS, a finding that was not evident in the subgroup with petrous plaque <3.5 mm (p for interaction = 0.027). CONCLUSIONS: The present study provided the first evidence supporting a potential etiological role of vulnerable petrous plaque in ESUS.


Assuntos
Doenças das Artérias Carótidas , Estenose das Carótidas , AVC Embólico , Embolia Intracraniana , Placa Aterosclerótica , Acidente Vascular Cerebral , Humanos , Doenças das Artérias Carótidas/complicações , AVC Embólico/complicações , Artéria Carótida Interna/diagnóstico por imagem , Placa Aterosclerótica/complicações , Placa Aterosclerótica/diagnóstico por imagem , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/complicações , Estenose das Carótidas/complicações , Embolia Intracraniana/complicações
7.
J Am Heart Assoc ; 11(21): e026737, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36300665

RESUMO

Background The potential causes or sources of embolic stroke of undetermined source (ESUS) vary. This study aimed to investigate the main cause of deep ESUS by evaluating nonstenotic intracranial atherosclerotic plaque. Methods and Results We retrospectively screened consecutive patients with unilateral anterior circulation ESUS. After excluding the patients with possible embolism from an extracranial artery such as aortic arch plaque, carotid plaque, and so on, the enrolled patients with ESUS were categorized into 2 groups: deep ESUS and cortical with/without deep ESUS. All patients underwent intracranial high-resolution magnetic resonance imaging to assess the characteristics of nonstenotic intracranial atherosclerotic plaque. Biomarkers of atrial cardiopathy (ie, P-wave terminal force in lead V1 on ECG, NT-proBNP [N-terminal pro-brain natriuretic peptide] and left atrial diameter) were collected. A total of 155 patients with ipsilateral nonstenotic intracranial atherosclerotic plaque were found, with 76 (49.0%) in deep ESUS and 79 (51.0%) in cortical with/without deep ESUS. We found more prevalent plaque in the M1 segment of the middle cerebral artery and the ostia of the perforator, with a smaller remodeling index plaque burden, and less frequent occurrence of complicated plaque in deep ESUS versus cortical with/without deep ESUS. Higher BNP (brain natriuretic peptide) levels and a higher prevalence of atrial cardiopathy in cortical with/without deep ESUS versus deep ESUS. Moreover, the discrimination of vulnerable plaque for predicting ESUS was significantly enhanced after adjusting for or further excluding patients with deep ESUS. Conclusions The current study provides the first high-resolution magnetic resonance imaging evidence that cortical with/without deep ESUS and deep ESUS should be 2 distinct entities and that atherosclerosis, not embolism, might be the main cause of deep ESUS.


Assuntos
Aterosclerose , AVC Embólico , Embolia , Cardiopatias , Arteriosclerose Intracraniana , Embolia Intracraniana , Placa Aterosclerótica , Acidente Vascular Cerebral , Humanos , Embolia Intracraniana/diagnóstico por imagem , Embolia Intracraniana/epidemiologia , Embolia Intracraniana/etiologia , AVC Embólico/epidemiologia , AVC Embólico/etiologia , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/complicações , Estudos Retrospectivos , Placa Aterosclerótica/complicações , Embolia/complicações , Imageamento por Ressonância Magnética , Aterosclerose/complicações , Aterosclerose/diagnóstico por imagem , Cardiopatias/complicações , Arteriosclerose Intracraniana/complicações , Arteriosclerose Intracraniana/diagnóstico por imagem , Fatores de Risco
8.
Spectrochim Acta A Mol Biomol Spectrosc ; 279: 121465, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-35687991

RESUMO

A new Mo1-xWxS2 two-dimensional nanosheets were prepared by the one-pot method. After certain Mo atoms in MoS2 were replaced by W ones in a hydrothermal reduction procedure, Mo1-xWxS2 was formed on the Mo foil. Well enhanced Mo1-xWxS2 nanosheets were prepared when the sodium tungstate concentration got under control. Various characterizations were carried out, which indicate that Mo1-xWxS2 nanosheets with good crystallinity. Compared with MoS2, the Raman intensity of Rhodamine 6G (10-6 M) was amplified by 1.7 times with Mo1-xWxS2 nanosheets as the substrate. The characteristic Raman peaks could still be clearly distinguished until the concentration of Rhodamine 6G (R6G), Methylene blue (MB) and Crystal violet (CV) down to 10-8, 10-8 and 10-7 M, respectively. With abundant edge active sites that facilitate charge transfer, Mo1-xWxS2 nanosheets could better enhance SERS signals of target detection molecules and get a good linear relationship exists within the concentration and Raman peak strength. In addition, R6G SERS detection also shows excellent reproducibility and long-term stability of this TMDs SERS substrate.


Assuntos
Nanopartículas Metálicas , Ligas , Nanopartículas Metálicas/química , Molibdênio , Reprodutibilidade dos Testes , Análise Espectral Raman/métodos
9.
Eur J Neurol ; 29(9): 2654-2663, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35593148

RESUMO

BACKGROUND AND PURPOSE: The aim was to investigate the characteristics of non-stenotic intracranial plaque (NSIP) in embolic stroke of undetermined source (ESUS) subtypes by high-resolution magnetic resonance imaging. METHODS: Consecutive patients with ESUS who were mandatory for high-resolution magnetic resonance imaging were retrospectively enrolled. Based on the location and arterial supply of the infarct, the ESUS were categorized into three types: cortical ESUS, subcortical ESUS and mixed ESUS. The NSIP parameters including plaque location, morphology (plaque distribution, remodeling index and plaque burden) and composition (thick fibrous cap, discontinuity of plaque surface, intraplaque hemorrhage and complicated plaque) were evaluated amongst the subtypes. RESULTS: Of 243 patients, there were 87 (35.8%) cortical ESUS, 127 (52.3%) subcortical ESUS and 29 (11.9%) mixed ESUS. Significant differences were found in plaque location (p < 0.001), plaque quadrant (p < 0.001), remodeling index (p < 0.001), plaque burden (p < 0.001), discontinuity of plaque surface (p < 0.001), intraplaque hemorrhage (p = 0.001) and complicated plaque (p < 0.001) of ipsilateral NISP amongst the different ESUS subtypes, except for fibrous cap (p = 0.135). However, no differences were found amongst contralateral NISP. In addition, the clinical characteristics of the differences between ESUS subtypes were striking, including age (p = 0.004), initial National Institutes of Health Stroke Scale (p < 0.001), coronary artery disease (p = 0.039), serum urea (p = 0.011) and creatinine (p = 0.002). CONCLUSION: This is the first report of significantly heterogeneous characteristics of ipsilateral NSIP and clinical findings amongst ESUS subtypes, which may suggest their different underlying mechanisms.


Assuntos
AVC Embólico , Embolia Intracraniana , Placa Aterosclerótica , Acidente Vascular Cerebral , Constrição Patológica , Humanos , Embolia Intracraniana/complicações , Embolia Intracraniana/diagnóstico por imagem , Placa Aterosclerótica/complicações , Placa Aterosclerótica/diagnóstico por imagem , Estudos Retrospectivos , Fatores de Risco , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/etiologia
10.
Spectrochim Acta A Mol Biomol Spectrosc ; 267(Pt 2): 120519, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34801391

RESUMO

Sensitive and selective detection of target analyte is very important in many fields such as commodity inspection and quality monitoring. In this work, based on the principle of competitive immunoassay, surface-enhanced Raman spectroscopy (SERS) was used to establish a rapid and highly sensitive method for the detection of trace amounts of bisphenol A in water. Here, Raman molecule 5,5-dithiobis-2-nitrobenzoic acid and anti-BPA antibody were conjugated with Au (core)@Ag (shell) nanoparticle to serve as SERS nanoprobe. After the SERS nanoprobe is combined with the substance to be tested, it uses the siphon effect to pass through the test line and the charging line on the test strip. And the Raman test was performed on the T line with a Raman spectrometer. The detection limitation was 0.1 pg/mL. Compared with the reported gas chromatography, liquid chromatography, fluorescence analysis, and other detection methods, SERS ICA does not demand complicated sample preparation procedures, and has the advantages of simple detection methods, quick results, High sensitivity, good specificity, and low technical demands for laboratory environment and testers. In addition, Raman spectrometers have gradually developed to be portable, making it easier to meet the needs of on-site rapid and highly sensitive detection, and will show broad prospects for applications in the fields of biomedical diagnosis and food safety monitoring.


Assuntos
Água Potável , Nanopartículas Metálicas , Compostos Benzidrílicos , Ouro , Fenóis , Tecnologia
11.
J Neurol Neurosurg Psychiatry ; 93(4): 351-359, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-34872980

RESUMO

OBJECTIVE: To assess (1) the association between atrial cardiopathy (AC) and non-stenotic intracranial complicated atherosclerotic plaque (NICAP) in patients with embolic stroke of undetermined source (ESUS) or small-vessel disease (SVD), and (2) the performance of previously proposed biomarkers to identify AC as the underlying aetiology in ESUS. METHODS: Based on our high-resolution MRI (HR-MRI) cohort, 403 subjects (243 ESUS and 160 SVD) were enrolled in the final analysis. All patients underwent intracranial HR-MRI to assess the presence of ipsilateral NICAP. Biomarkers of AC (ie, P-wave terminal force in lead V1 (PTFV1) on ECG, N-terminal probrain natriuretic peptide (NT-proBNP), high-sensitivity cardiac troponin T and left atrial diameter) were collected within 24 hours after admission. RESULTS: Among patients without ipsilateral NICAP, we found an association between the presence of AC (adjusted OR (aOR): 4.76, 95% CI 2.48 to 9.14), increased PTFV1 (aOR: 5.70, 95% CI: 2.43 to 13.39) and NT-proBNP (aOR: 1.65, 95% CI: 1.16 to 2.35) with ESUS. This association was not evident among patients with ipsilateral NICAP. The discrimination between ESUS versus SVD by AC/AC-related biomarkers was significantly improved after excluding ipsilateral NICAP. Similarly, the discrimination between ESUS and SVD by ipsilateral NICAP was notably augmented after excluding AC, PTFV1 and NT-proBNP. INTERPRETATION: AC is more prevalent in patients who had ESUS without ipsilateral NICAP compared with patients with, implying that AC and ipsilateral NICAP are two distinct, competing aetiologies of ESUS. Among the AC biomarkers studied in this analysis, PTFV1 seems to be the most informative.


Assuntos
AVC Embólico , Cardiopatias , Embolia Intracraniana , Placa Aterosclerótica , Acidente Vascular Cerebral , Biomarcadores , AVC Embólico/etiologia , Cardiopatias/complicações , Cardiopatias/diagnóstico por imagem , Humanos , Embolia Intracraniana/complicações , Embolia Intracraniana/diagnóstico por imagem , Placa Aterosclerótica/complicações , Placa Aterosclerótica/diagnóstico por imagem , Fatores de Risco , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/diagnóstico por imagem
12.
Spectrochim Acta A Mol Biomol Spectrosc ; 265: 120366, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34509888

RESUMO

Pesticide detection is of tremendous importance in agriculture, and Raman spectroscopy/Surface-Enhanced Raman Scattering (SERS) has proven extremely effective as a stand-alone method to detect pesticide residues. Machine learning may be able to automate such detection, but conventional algorithms require a complete database of Raman spectra, which is not feasible. To bypass this problem, the present study describes a transfer learning method that improves the algorithm's accuracy and speed to extract features and classify Raman spectra. The transfer learning model described here was developed through the following steps: (1) the classification model was pre-trained using an open-source Raman spectroscopy database; (2) the feature extraction layer was saved after training; and (3) the training model for the Raman spectroscopy database was re-established while using self-tested pesticides and keeping the feature extraction layer unchanged. Three models were evaluated with or without transfer learning: CNN-1D, Resnet-1D, and Inception-1D, and they have improved the accuracy of spectrum classification by 6%, 2%, and 3%, with reduced training time and increased curve smoothness. These results suggest that transfer learning can improve the feature extraction capability and therefore accuracy of Raman spectroscopy models, expanding the range of Raman-based applications where transfer learning model can be used to identify the spectra of different substances.


Assuntos
Resíduos de Praguicidas , Praguicidas , Algoritmos , Aprendizado de Máquina , Redes Neurais de Computação , Resíduos de Praguicidas/análise
13.
Spectrochim Acta A Mol Biomol Spectrosc ; 255: 119717, 2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-33794423

RESUMO

The silver nanoparticles have been frequently used in SERS detection, for their unique optical properties and sensitive surface Raman enhancement properties. However, as the preparation of silver nanoparticles will use polyvinylpyrrolidone (PVP) to achieve the effect of reducing agent and surfactant, the surface of the prepared silver nanoparticles will be wrapped by PVP, forming an insulating layer and an ill-defined AgNPs interface, which limits the plasmonic coupling between the laminates of AgNPs. This paper reported a simple method to remove PVP for high performance and reusable SERS substrate, and the residue of PVP was studied after clean centrifugal by ethanol or water. When the number of cleaning times reached 10, there was basically no residual of PVP. The cleaned AgNPs interface effectively enhanced the plasma resonance of the local surface (LSPR) and greatly improved the SERS activity of the substrate. Moreover, probe molecules (R6G) are introduced to study the influence of single molecule PVP on subsequent detection. Through the competitive relationship between the two, it can be concluded that residual PVP has basically no influence on detection of the molecular which absorbed stronger than PVP, and the remaining PVP can be ignored.

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