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1.
Eur Geriatr Med ; 2024 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-38441837

RESUMO

PURPOSE: It has recently been recommended that Rate of Force Development (RFD) be evaluated in addition to maximal muscle strength. There are no studies on RFD of toe pressure strength, and its importance in older adults and the extent to which it is associated with aging needs to be clarified. This study purpose was to examine the association between the RFD of toe pressure strength and timed up and go test (TUG) in an age-specific study. METHODS: This study is a cross-sectional study. Participants in the study included 159 younger adults (26.3 ± 13.1 years, 52% male) and 88 older adults (75.0 ± 6.2 years, 26% male). The RFD of toe pressure strength was determined from the force-time curve obtained during the toe pressure strength assessment, and the ability to exert maximum muscle force in the shortest possible time was assessed. Regression analysis was performed for each group to test the association between RFD of toe pressure strength and TUG by age. RESULTS: Younger adults showed no association between TUG and RFD of toe pressure strength, and significant association between TUG and RFD of toe pressure strength was found only in the older adults (standard regression coefficient = - 0.19, p = 0.048). CONCLUSION: This study showed a significant association between TUG and RFD of toe pressure strength in older adults. These findings show that RFD is one of the functions that should be assessed, particularly in older adults. Furthermore, it was suggested that approaching RFD could improve gait, standing, and sitting movements.

2.
Neuropsychiatr Dis Treat ; 19: 1695-1707, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37546515

RESUMO

Background: Preventive interventions for subthreshold depression (StD) are essential to reduce the incidence of major depressive disorder. Our smartphone application presenting positive word stimulation in video (ie, Subliminal Priming with Supraliminal Reward Stimulation, SPSRS) was suggested to improve depressive symptoms in people with StD, although it is unclear whether it can immediately improve depressed mood. This pilot randomized controlled trial (RCT) aimed to investigate the preliminary efficacy of SPSRS application intervention on depressive mood in people with StD. Methods: Thirty-two participants with StD were randomly assigned to the experimental (n = 16) or control group (n = 16). The experimental group received SPSRS application intervention (10-minute video with positive word stimulation) and the control group received YouTube application intervention (10-minute video without positive word stimulation). Both groups used identical iPhones managed by the research team. The primary outcome was the change from baseline in depression-dejection on the Profile of Mood States 2nd Edition-Adult Short (POMS 2-A Short) after the intervention. Results: No participants dropped out of the study. The experimental group showed a small improvement in depression-dejection on the POMS 2-A Short score (adjusted Hedges's g = -0.32) compared to the control group. Post-hoc power analyses estimated a sample size of 56 per group (112 total) to evaluate depression-dejection on the POMS 2-A Short in a future full-scale RCT. Conclusion: SPSRS application intervention may be effective in immediately improving depressive mood in people with StD. A future full-scale RCT based on a formally calculated sample size should be conducted to replicate these findings.

3.
Ann Geriatr Med Res ; 27(2): 106-115, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37127533

RESUMO

BACKGROUND: Various functions are involved in prefrailty. However, no studies have examined more relevant functions. Therefore, this study examined the domains of the Kihon Checklist (KCL) associated with prefrailty by comparing them to robustness measures, using the KCL to comprehensively assess life-related functions in community-dwelling older adults. METHODS: The 194 (mean age, 75±6 years) participants were community-dwelling older adults. Their robustness and preferences were assessed using the Japanese Cardiovascular Health Study criteria. Comprehensive life-related functions were assessed using the KCL, and each physical function was measured. RESULTS: The main KCL characteristics associated with robustness and prefrailty were physical function (odds ratio [OR]=1.83; 95% confidence interval [CI], 1.17-2.88), nutritional status (OR=8.16; 95% CI, 2.96-22.48), and depressed mood (OR=3.46; 95% CI, 1.76-6.79). In particular, older adults had difficulty moving, including climbing stairs and getting up from a chair, which suggested a strong fear of falling. The participants also reported psychological characteristics such as low life fulfillment, a low sense of self-usefulness, and a strong sense of boredom. CONCLUSIONS: Prefrail individuals were characterized by poor physical function and nutritional status, as well as depressive mood. Prefrailty may be prevented or improved by approaches to improve physical function and fear of falling in addition to psychological interventions that encourage activity and a sense of self-usefulness.

4.
ACS Appl Mater Interfaces ; 15(6): 8567-8578, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36715349

RESUMO

Lubricants with desirable frictional properties are important in achieving an energy-saving society. Lubricants at the interfaces of mechanical components are confined under high shear rates and pressures and behave quite differently from the bulk material. Computational approaches such as nonequilibrium molecular dynamics (NEMD) simulations have been performed to probe the molecular behavior of lubricants. However, the low-shear-velocity regions of the materials have rarely been simulated owing to the expensive calculations necessary to do so, and the molecular dynamics under shear velocities comparable with that in the experiments are not clearly understood. In this study, we performed NEMD simulations of extremely confined lubricants, i.e., two molecular layers for four types of lubricants confined in mica walls, under shear velocities from 0.001 to 1 m/s. While we confirmed shear thinning, the velocity profiles could not show the flow behavior when the shear velocity was much slower than thermal fluctuations. Therefore, we used an unsupervised machine learning approach to detect molecular movements that contribute to shear thinning. First, we extracted the simple features of molecular movements from large amounts of MD data, which were found to correlate with the effective viscosity. Subsequently, the extracted features were interpreted by examining the trajectories contributing to these features. The magnitude of diffusion corresponded to the viscosity, and the location of slips that varied depending on the spherical and chain lubricants was irrelevant. Finally, we attempted to apply a modified Stokes-Einstein relation at equilibrium to the nonequilibrium and confined systems. While systems with low shear rates obeyed the relation sufficiently, large deviations were observed under large shear rates.

5.
Neuropsychiatr Dis Treat ; 17: 2739-2748, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34456565

RESUMO

BACKGROUND: Major depressive disorder (MDD) is an important public health problem. Thus, preventive interventions against subthreshold depression (StD), which is one of the key risk factors for the development of MDD, are important. The study developed a smartphone application (SPSRS) that improves depressive symptoms in people with StD by automatically presenting positive word stimuli during videos. The SPSRS application has the potential to improve depressive symptoms in people with StDs. However, whether it can immediately improve depressed moods in people with StD is unclear. The study presents a protocol for investigating the immediate effects of the SPSRS application intervention on depressed mood in people with StD. METHODS: The study is designed as an open-label, parallel-group, and pilot randomized controlled trial (RCT). Thirty-two people who meet the criteria for StD (Beck Depression Inventory-II score of 10 points or more and fails to meet the diagnostic criteria for MDD) will be recruited and studied. It compares the immediate effects of the SPSRS application intervention (with positive word stimulus in a 10-minute video; n = 16) and YouTube application intervention (without positive word stimulus in 10-minute video; n = 16). The primary outcome is the change in the score for the Profile of Mood States 2nd Edition-Adult Short after 10 minutes of intervention. The secondary outcome is the change in the State-Trait Anxiety Inventory State after 10 min of intervention. DISCUSSION: The pilot RCT is the first to evaluate the immediate effects of the SPSRS application intervention on depressed mood in people with StD. The results are expected to provide a preliminary outcome of the immediate effect of the SPSRS application on the depressed mood of people with StD and aid in planning a full-scale trial. TRIAL REGISTRATION: ClinicalTrials.gov; Identifier: NCT03864484.

6.
Anal Chim Acta ; 1087: 11-19, 2019 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-31585558

RESUMO

We demonstrate a recognition and feature visualization method that uses a deep convolutional neural network for Raman spectrum analysis. The visualization is achieved by calculating important regions in the spectra from weights in pooling and fully-connected layers. The method is first examined for simple Lorentzian spectra, then applied to the spectra of pharmaceutical compounds and numerically mixed amino acids. We investigate the effects of the size and number of convolution filters on the extracted regions for Raman-peak signals using the Lorentzian spectra. It is confirmed that the Raman peak contributes to the recognition by visualizing the extracted features. A near-zero weight value is obtained at the background level region, which appears to be used for baseline correction. Common component extraction is confirmed by an evaluation of numerically mixed amino acid spectra. High weight values at the common peaks and negative values at the distinctive peaks appear, even though the model is given one-hot vectors as the training labels (without a mix ratio). This proposed method is potentially suitable for applications such as the validation of trained models, ensuring the reliability of common component extraction from compound samples for spectral analysis.

7.
Anal Sci ; 33(9): 1007-1012, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28890483

RESUMO

Ligand exchange reactions of a monomeric zirconium carbonate complex with carboxylic acids were studied by means of extended X-ray absorption fine structure (EXAFS), UV absorption spectrophotometry and Raman spectrometry. Three carboxylic acids, gluconic acid, and L-tartaric acid and citric acid, which are mono-, di- and tri-carboxylic acids, respectively, were employed in this study. These three carboxylic acids gave different spectral signatures and concentration dependences, respectively. In the gluconic acid system, the peaks on Fourier transform of EXAFS spectrum and Raman spectrum caused by carbonate ion coordinating to zirconium atom were obviously decreased with increasing gluconic acid concentration compared to the other two carboxylic acid systems. This indicates the high association ability of gluconic acid to zirconium, which was revealed by UV spectrophotometric analysis.

8.
Sci Rep ; 5: 13738, 2015 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-26345206

RESUMO

Geranylgeranylacetone (GGA) is used to treat patients suffering from peptic ulcers and gastritis. We examined the effect of GGA on Helicobacter pylori, which is a causative factor of gastrointestinal diseases. Previously, we have reported that GGA binds specifically to the molecular chaperone HSP70. In this paper, we report that GGA bounds to H. pylori HSP70 (product of the DnaK gene) with 26-times higher affinity than to human HSP70, and induced large conformational changes as observed from surface plasmon resonance and circular dichroism. Binding of GGA suppressed the activity of the H. pylori chaperone. GGA also altered several characteristics of H. pylori cells. GGA-treated cells elicited enhanced interleukin-8 production by gastric cancer cell lines and potentiated susceptibility to complement as compared to untreated cells. GGA also caused morphological alterations in H. pylori as reflected in fewer coccoid-like cells, suggesting that GGA converts H. pylori to an actively dividing, spiral state (vegetative form) from a non-growing, coccoid state. This morphological conversion by GGA resulted in accelerated growth of H. pylori. These results suggest a model in which GGA sensitizes H. pylori to antibiotic treatment by converting the cells to an actively growing state.


Assuntos
Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Diterpenos/metabolismo , Proteínas de Choque Térmico HSP70/química , Proteínas de Choque Térmico HSP70/metabolismo , Helicobacter pylori/metabolismo , Conformação Proteica , Linhagem Celular Tumoral , Diterpenos/farmacologia , Helicobacter pylori/efeitos dos fármacos , Helicobacter pylori/crescimento & desenvolvimento , Humanos , Ligação Proteica , Proteínas Recombinantes , Ressonância de Plasmônio de Superfície
9.
Dalton Trans ; 44(2): 645-52, 2015 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-25384541

RESUMO

The speciation of zirconium complexes in ammonium zirconium carbonate (AZC) solutions should be further studied in order to develop high-performance AZC complexes for use in elaborate industrial materials. Thus, the speciation and the structure of various zirconium species in ammonium zirconium carbonate solutions were investigated over a wide range of total carbonate and ammonium concentrations. By employing extended X-ray absorption fine structure analysis, and Raman and (13)C NMR spectroscopy, it was found that four carbonate ions coordinate bidentately to the zirconium ion. In addition, the exact concentration ranges of carbonate and ammonium in AZC necessary to generate the monomeric zirconium carbonate complex [Zr(CO3)4](4-) were determined.

10.
J Phys Ther Sci ; 26(12): 1861-3, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25540482

RESUMO

[Purpose] The purpose of this study was to evaluate the lower limb muscle strength of the community-dwelling elderly, with or without cognitive decline, using isometric knee extension strength (IKES) and the 30-second chair stand test (CS-30). [Subjects] A total of 306 community-dwelling elderly participated in this study. Assessment items were the CS-30, IKES, Mini-Mental State Examination (MMSE), and Trail-Making Test Part A (TMT-A). [Methods] Participants were divided into three groups according to their MMSE score: cognitive impairment (MMSE ≤ 24), cognitive decline (MMSE 25 to 27), and normal (MMSE ≥ 28). We compared IKES and CS-30 among the three groups. [Results] IKES was not significantly different among the three groups. However, the CS-30 was significantly different among the three groups. Upon further analysis the CS-30 score of each group, when adjusted for age and TMT-A, did not indicate a significant difference. [Conclusion] These results suggest that the lower limb muscle strength of the elderly does not differ with cognitive decline. Moreover, we suggest that when using the CS-30 score as an indicator of lower limb muscle strength attentional function should be taken into account.

11.
J Nanosci Nanotechnol ; 12(8): 6596-8, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22962794

RESUMO

The aggregation of Au nanoparticle (AuNP) on a glass surface functionalized with 3-aminopropyltrimethoxysilane (APTMS) was studied by means of UV-vis spectroscopy and AFM measurements. The optical response of AuNP due to localized surface plasmon resonance (LSPR) was increased with the increment of AuNP amount on the functionalized glass surface, then the changes of spectral shape corresponds to the aggregate formation was finally observed. The AFM image shows in homogeneous aggregation of nanoparticles on the substrate surface. Three-dimensional aggregate growth was observed.

12.
Anal Sci ; 25(2): 241-8, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19212060

RESUMO

Physicochemical analyses of Au nanoparticle monolayer formation on a glass surface functionalized with 3-aminopropyltrimethoxysilane (APTMS) and ethyltrimethoxysilane (ETMS) were performed for fabricating a nanoarchitecture of metal nanoparticles using self-assembly. The Au nanoparticle surface density on the functionalized glass surface correlated linearly with the optical response because of Au-nanoparticle localized surface plasmon resonance (LSPR). This relation enabled assessment of the Au nanoparticle deposition. A Frumkin isotherm showed the deposition of Au nanoparticles on the APTMS or APTMS/ETMS functionalized glass surface. For an APTMS-derivatized surface, the affinity between the Au nanoparticles and the surface decreased with the lowering of the APTMS surface coverage. The interaction parameter exhibited attractive interaction of 30-nm-diameter Au nanoparticles; 12 nm particles were repulsive. Adsorption isotherm experiments using Au nanoparticles on glass surfaces with an APTMS and ETMS mixed layer suggest that hydrophobic interaction between Au nanoparticles' bare gold surfaces caused the attractive interaction among 30-nm-diameter nanoparticles.

13.
Anal Sci ; 25(1): 109-14, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19139583

RESUMO

In this report, we have developed a novel quantitative RT-PCR protocol in which the procedure including mRNA purification can be performed in an all-in-one tube. To simplify gene expression analysis, oligo-dT(30) immobilized PCR tubes were used serially to capture mRNA, synthesize solid-phase cDNA, and amplify specific genes. The immobilized oligo-dT(30) can efficiently capture mRNA directly from crude human cell lysates. The captured mRNA is then amplified by one-step reverse transcription PCR (RT-PCR) with initial cDNA synthesis followed by PCR. In RT-PCR, this new reusable PCR tube device can be employed for multiple PCR amplifications with different primer sets from a solid-phase oligo-dT(30) primed cDNA library. This paper introduces a novel and highly reliable all-in-one tube method for rapid cell lysis, followed by quantitative preparation and expression analysis of target mRNA molecules with small amounts of sample. This procedure allows all steps to be carried out by sequential dilution in a single tube, without chemical extraction. We demonstrate the utility of this novel method by quantification of two housekeeping genes, beta-actin and GAPDH, in HeLa cells. We believe this new PCR device can be useful as a platform for various mRNA expression analyses, including basic research, drug screening, and molecular toxicology, as well as for molecular pathological diagnostics.


Assuntos
Perfilação da Expressão Gênica/instrumentação , Actinas/genética , Perfilação da Expressão Gênica/métodos , Gliceraldeído-3-Fosfato Desidrogenases/genética , Células HeLa , Humanos , Métodos , Oligodesoxirribonucleotídeos , Polímeros , RNA Mensageiro/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa/instrumentação
14.
Nucleic Acids Res ; 35(1): e3, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17135189

RESUMO

DNA microarrays are routinely used to monitor gene expression profiling and single nucleotide polymorphisms (SNPs). However, for practically useful high performance, the detection sensitivity is still not adequate, leaving low expression genes undetected. To resolve this issue, we have developed a new plastic S-BIO PrimeSurface with a biocompatible polymer; its surface chemistry offers an extraordinarily stable thermal property for a lack of pre-activated glass slide surface. The oligonucleotides immobilized on this substrate are robust in boiling water and show no significant loss of hybridization activity during dissociation treatment. This allowed us to hybridize the templates, extend the 3' end of the immobilized DNA primers on the S-Bio by DNA polymerase using deoxynucleotidyl triphosphates (dNTP) as extender units, release the templates by denaturalization and use the same templates for a second round of reactions similar to that of the PCR method. By repeating this cycle, the picomolar concentration range of the template oligonucleotide can be detected as stable signals via the incorporation of labeled dUTP into primers. This method of Multiple Primer EXtension (MPEX) could be further extended as an alternative route for producing DNA microarrays for SNP analyses via simple template preparation such as reverse transcript cDNA or restriction enzyme treatment of genome DNA.


Assuntos
Primers do DNA/química , Metacrilatos/química , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Polietilenoglicóis/química , Taq Polimerase/metabolismo , Cinética , Sondas de Oligonucleotídeos , Análise de Sequência de DNA , Temperatura
15.
Anal Sci ; 22(12): 1537-45, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17159312

RESUMO

In the present work, a convenient microarray SNP typing system has been developed using a plastic base that covalently immobilizes amino-modified oligonucleotides. Reliable SNP allele discrimination was achieved by using allelic specificity-enhanced enzymatic extension of immobilized oligonucleotide primer, with a locked nucleic acid (LNA) modification at the SNP-discriminating 3'-end nucleotide. Incorporation of multiple biotin-dUTP molecules during primer extension, followed by binding of alkaline phosphatase-conjugated streptavidin, allowed optical detection of the genotyping results through precipitation of colored alkaline phosphatase substrates onto the surface of the plastic base. Notably, rapid primer extension was demonstrated without a preliminary annealing step of double-stranded template DNA, allowing overall processes to be performed within a couple of hours. Simultaneous evaluation of three SNPs in the genes TGFB1, SOD2 and APEX1, previously investigated for association with radiation sensitivity, in 25 individuals has shown perfect assignment with data obtained by another established technique (MassARRAY system).


Assuntos
Técnicas de Amplificação de Ácido Nucleico/métodos , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Oligonucleotídeos/genética , Polimorfismo de Nucleotídeo Único/genética , Fosfatase Alcalina , Alelos , Biotina , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/genética , Genótipo , Humanos , Nucleotídeos/química , Oligonucleotídeos/química , Estreptavidina , Superóxido Dismutase/genética , Fator de Crescimento Transformador beta1/genética
16.
Anal Bioanal Chem ; 386(3): 639-44, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16823566

RESUMO

Antibody binding to bovine serum albumin (BSA) and human serum albumin (HSA) immobilized onto gold nanoparticles was studied by means of localized surface plasmon resonance (LSPR) spectroscopy. Amine-modified glass was prepared by self-assembly of amine-terminated silane on substrate, and gold (Au) nanoparticles were deposited on the amine-modified glass substrate. Au nanoparticles deposited on the glass surface were functionalized by BSA and HSA. BSA immobilization was confirmed by LSPR spectroscopy in conjunction with surface-enhanced Raman scattering spectroscopy. Then, LSPR response attributable to the binding of anti-BSA and anti-HSA to BSA- and HSA-functionalized Au nanoparticles, respectively, was examined. Anti-HSA at levels larger than approximately 10 nM could be detected by HSA-immobilized chips with LSPR optical response, which was saturated at concentrations greater than approximately 650 nM of anti-HSA.


Assuntos
Anticorpos/metabolismo , Técnicas Biossensoriais/métodos , Ouro/química , Nanotecnologia/métodos , Albumina Sérica/química , Animais , Anticorpos/química , Técnicas Biossensoriais/instrumentação , Bovinos , Vidro/química , Ouro/metabolismo , Humanos , Ligação Proteica , Albumina Sérica/metabolismo , Soroalbumina Bovina/química , Soroalbumina Bovina/metabolismo , Ressonância de Plasmônio de Superfície , Propriedades de Superfície
17.
Langmuir ; 22(6): 2482-6, 2006 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-16519444

RESUMO

Interfacial ion-association adsorption and aggregation of a water-soluble porphyrin, tetrakis(4-sulfonatephenyl)porphyrin (TPPS) diacid, which was promoted by a cationic cetyltrimethylammonium ion (CTA(+)), was studied by second harmonic generation (SHG) spectroscopy. Comparing the interfacial SH spectrum with the transmission absorption spectrum of TPPS in the aqueous solution elucidated the aggregation behavior of TPPS at the heptane/water interface. The time-dependent SHG spectra for TPPS aggregation and the interfacial tension lowering in the presence of CTA(+) were discussed on the basis of an electrostatic adsorption model. Then, it was suggested that TPPS diacid was highly concentrated by the ion-association with CTA(+) at the interface, which was the intermediate state before the final aggregated state.

18.
Intern Med ; 45(1): 1-4, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16467596

RESUMO

OBJECTIVE: Treatment with a free radical scavenger could be a new option for ischemic brain attack, however, little is known about the alteration of oxidative stress markers induced by edaravone, a novel free radical scavenger, in human ischemic brain attack. METHODS: We investigated the effects of edaravone on the oxidative stress markers in patients with ischemic brain attack. Twenty-one patients with ischemic brain attack and 19 controls were enrolled in this study. Blood samples were obtained just before and soon after the first administration of edaravone (30 mg) or ozagrel (40 mg). Intracellular reactive oxygen species of neutrophils were measured using 6-carboxy-2', 7'-dichlorodihydrofluorescin diacetate and a fluorescence-activated cell sorter. Superoxide from neutrophils, induced by phorbol myristate acetate (PMA), was determined by luminol-amplified chemiluminescence assay. RESULTS: Treatment with 30 mg of edaravone significantly decreased the intracellular reactive oxygen species (ROS) of neutrophils (Wilcoxon test, p=0.0001) and PMA-induced superoxide produced by neutrophils (Wilcoxon test, p=0.001). Ozagrel did not alter the intracellular ROS or superoxide production of neutrophils. CONCLUSION: Reduction of intracellular ROS and suppression of superoxide production in neutrophils provide a potential explanation for the clinical efficacy of edaravone in patients with ischemic brain attack.


Assuntos
Antipirina/análogos & derivados , Isquemia Encefálica/sangue , Isquemia Encefálica/tratamento farmacológico , Sequestradores de Radicais Livres/uso terapêutico , Radicais Livres/metabolismo , Neutrófilos/efeitos dos fármacos , Neutrófilos/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Idoso , Idoso de 80 Anos ou mais , Antipirina/uso terapêutico , Edaravone , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
19.
Anal Sci ; 20(11): 1489-91, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15566138

RESUMO

The direct measurement of the circular dichroism (CD) spectra of liquid/liquid interface has been achieved for the first time by the centrifugal liquid membrane (CLM) method combined with a conventional CD spectropolarimetry. In the sample chamber of the CD spectropolarimeter, a cylindrical glass cell containing small amounts of organic and aqueous phases was rotated at ca. 7000 rpm to generate a two-phase liquid membrane with a high specific interfacial area. The CD spectra of the J-aggregate of protonated 5,10,15,20-tetraphenylporphyrin formed at the toluene/sulfuric acid interface in the rotating cell have been measured. The results demonstrated the novelty and advantages of this method.

20.
Anal Sci ; 20(9): 1347-52, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15478347

RESUMO

Oleate-stabilized silver colloids of 5-nm-diameter were adsorbed to a toluene/water interface, and surface enhanced Raman scattering (SERS) spectra from these colloids were measured under the total internal reflection (TIR) condition. From the observed spectra, we examined the states of oleate ions and toluene molecules on silver colloids at the liquid/liquid interfacial region. The TIR-SERS spectra of oleate ions showed stronger peaks of the carboxylate group and the ethylene group than those of alkyl chains. From these results, it was found that the oleate ions were adsorbed on the silver surface in two different ways at the liquid/liquid interface; the carboxylate group adsorbed in the organic phase side, while the ethylene group adsorbed in the aqueous phase side. The shifts of the toluene in the interfacial SERS spectra were identical to those of bulk toluene, though the relative intensities among the peaks were not same. This result suggested that the toluene was adsorbed with a weak interaction, but was significantly enhanced by the local electromagnetic field at the colloid surface.

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