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Vin?cius C. De Franco,Gustavo M. B. Castro,Jeaneth Corredor,Daniel Mendes,Jo?o E. Schmidt 한국탄소학회 2017 Carbon Letters Vol.21 No.-
Cobalt was electrodeposited onto chemical vapor deposition (CVD) graphene/Si/SiO2 substrates, during different time intervals, using an electrolyte solution containing a low concentration of cobalt sulfate. The intention was to investigate the details of the deposition process (and the dissolution process) and the resulting magnetic properties of the Co deposits on graphene. During and after electrodeposition, in-situ magnetic measurements were performed using an (AGFM). These were followed by ex situ morphological analysis of the samples with ΔtDEP 30 and 100 s by atomic force microscopy in the non-contact mode on pristine CVD graphene/SiO2/Si. We demonstrate that it is possible to electrodeposit Co onto graphene, and that in-situ magnetic measurements can also help in understanding details of the deposition process itself. The results show that the Co deposits are ferromagnetic with decreasing coercivity (HC) and demonstrate increasing magnetization on saturation (MSAT) and electric signal proportional to remanence (Mr), as a function of the amount of the electrodeposited Co. It was also found that, after the end of the dissolution process, a certain amount of cobalt remains on the graphene in oxide form (this was confirmed by X-ray photoelectron spectroscopy), as suggested by the magnetic measurements. This oxide tends to exhibit a limited asymptotic amount when cycling through the deposition/dissolution process for increasing deposition times, possibly indicating that the oxidation process is similar to the graphene surface chemistry.
Fingerprint and authenticity roasted coffees by 1H-NMR: the Brazilian coffee case
Aline Theodoro Toci,Marcos Vinı´cius de Moura Ribeiro,Paulo Roberto Aparecido Bueno de Toledo,Nivaldo Boralle,Helena Redigolo Pezza,Leonardo Pezza 한국식품과학회 2018 Food Science and Biotechnology Vol.27 No.1
With globalization, it has become necessary to adopt policies to regulate the coffee market, addressing problems including the authenticity and traceability of products. It is therefore important to establish methodologies that can help to safeguard the interests of producer countries and add value to products. For this purpose, the use of NMR combined with multivariate statistical procedures can be an attractive option. The aim of this study was to develop a fast and effective technique, using 1H NMR coupled with multivariate statistics, to create a fingerprint of roasted coffees, distinguishing them according to the main Brazilian producer regions. Several compounds suitable for differentiating roasted coffees were identified in the fingerprint. Discriminant analysis revealed good distinction among the samples. The compounds catechol, trigonelline, caffeine, and n-methylpyridine were most important for the differentiation. The findings should assist coffee-producing countries in adopting measures to protect their markets and to add value to coffee products.
Mobility and density relaxation of photogenerated charge carriers in organic materials
R. Osterbacka,A.Pivrikas,G.Ju ska,K.Genevi cius,K.Arlauskas,H.Stubb 한국물리학회 2004 Current Applied Physics Vol.4 No.5
We have measured mobility and density relaxation of photogenerated charge carriers in regiorandom poly(3-hexylthiophene)using novel extraction current transient techniques. We show how to obtain time-dependent mobilityl and charge carrier densitypusing independent measurements. The results showl / t. 0:42 independent on charge carrier density. The carrier density follows abimolecular decay with the bimolecular recombination coecientb ¼ 7:2 . 10. 13 cm3/s. The measured time-of-ight current fol-lows closely the estimated time decay asjðtÞ/pðtÞl ðtÞ, with deviation arising from extraction of the generated charge carriers.
Marielle Bazzo Di Domê,nico,Henrique Cesca,Thales Henrique Jincziwski Ponciano,Renan Brandenburg dos Santos,Ulysses Lenz,Viní,cius Picoli Antunes,Vinicius Webber Godinho,Kauê, Collares,Pedro Henrique 한국역학회 2021 Epidemiology and Health Vol.43 No.-
OBJECTIVES: To evaluate the effectiveness of hydrogen peroxide (H2O2) in the form of mouthwash and nasal spray as an auxiliary treatment for coronavirus disease 2019 (COVID-19). METHODS: Forty hospitalized patients who tested positive for severe acute respiratory syndrome coronavirus 2 using a reverse-transcription polymerase chain reaction test were evaluated. They were randomly divided into an experimental group (n=20; gargling with 1.0% H2O2 and nasal wash with 0.5% H2O2) or a control group (n=20). The solutions were used for 7 days and the patients were monitored every 2 days, for a total of 8 days. At check-ups, patients were asked about their symptoms and possible adverse effects of the solutions. The presence and severity (mild, moderate, or severe) of symptoms were recorded. Data were compared using the Student test and the Fisher exact test (α=0.05). RESULTS: There was no significant difference between the 2 groups in the length of hospital stay (p=0.65). The most frequent symptom on day 0 was coughing (72.0% in the experimental group and 76.5% in the control group), which abated over time. There was no significant difference between the groups in the evaluated symptoms. Most (75.0%) of the patients in the experimental group presented a reduction in dyspnea between days 0 and 2. Few patients reported adverse effects from the use of the solutions. CONCLUSIONS: H2O2 as a mouthwash and nasal spray is safe to use. There is insufficient evidence to demonstrate that H2O2 is effective as an auxiliary treatment for hospitalized COVID-19 patients.
Cryogenic photoluminescence imaging system for nanoscale positioning of single quantum emitters
Liu, Jin,Davanç,o, Marcelo I.,Sapienza, Luca,Konthasinghe, Kumarasiri,De Miranda Cardoso, José,Viní,cius,Song, Jin Dong,Badolato, Antonio,Srinivasan, Kartik American Institute of Physics 2017 Review of scientific instruments Vol.88 No.2
Photomodification of carrier lifetime and diffusivity in AlGaN epitaxial layers
Zydr unas Podlipskas,Ram unas Aleksiej unas,Saulius Nargelas,Ye Seul Yun,J uras Mickevi cius,Ar unas Kadys,Chong Yun Kang,Michael S. Shur,Max Shatalov,Jinwei Yang,Remis Gaska 한국물리학회 2016 Current Applied Physics Vol.16 No.6
Nonradiative recombination rate and diffusivity of nonequilibrium carriers were modified by intense laser pulses in AlGaN epilayers with Al content ranging from 16 to 71%. The epilayers were examined before and after the photomodification using light-induced transient grating and photoluminescence spectroscopy techniques. The photomodification resulted in (i) enhancement of the nonradiative recombination rate and (ii) large changes of the diffusion coefficient of the nonequilibrium carriers, without imposing any macroscopic structural damage to the epilayers. The photomodification effect on the recombination rate was stronger in the layers with higher Al content indicating the involvement of the Al atoms in this process. The carrier diffusivity exhibited a rapid initial increase as a consequence of the photomodification followed by a slow decline, as the photomodification duration was increased. The enhancement of the diffusion coefficient of up to 2.4 times was accompanied by 13% decrease in the carrier lifetime.
Marielle Bazzo Di Domê,nico,Kauê, Collares,Renan Brandenburg dos Santos,Ulysses Lenz,Viní,cius Picoli Antunes,Vinicius Webber Godinho,Henrique Cesca,Thales Henrique Jincziwski Ponciano,Pedro Henrique 한국역학회 2021 Epidemiology and Health Vol.43 No.-
OBJECTIVES: This study evaluated the effectiveness of hydrogen peroxide (H2O2) as mouthwash and nasal spray on symptom relief in coronavirus disease 2019 (COVID-19) patients. METHODS: Patients positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), who were treated in a hos-pital or at home, and patients’ family members (not positive for SARS-CoV-2), were randomized into 2 groups: experimental (1% H2O2 for gargling, 0.5% H2O2 for nasal wash), and control. Patients gargled the solution 3 times a day, and applied the nasal spray twice a day, for a 7-day period. Family members received the same treatment as the treated COVID-19 patient. The re-searchers contacted patients every 2 days over an 8-day period. An average post-treatment interval of 8 days passed before test-ing family members. RESULTS: The most frequent symptoms on day 0 were cough, loss of taste, and hyposmia; there were no significant differences between groups, independent of the period. The symptom of dyspnea presented a significant difference between days 2 and 4 (p< 0.05). Among family members, 86.0% had no antibodies, 2.3% had antibodies, and 11.6% had active infections (4 in the ex-perimental group and 6 in the control group). The most frequent adverse effects in the H2O2 group were a burning throat and nose. CONCLUSIONS: H2O2 was not effective for the relief of COVID-19 symptoms and was associated with reports of transient adverse effects.
Vinícius C. De Franco,Gustavo M. B. Castro,Jeaneth Corredor,Daniel Mendes,João E. Schmidt 한국탄소학회 2017 Carbon Letters Vol.21 No.-
Cobalt was electrodeposited onto chemical vapor deposition (CVD) graphene/Si/SiO2 substrates, during different time intervals, using an electrolyte solution containing a low concentration of cobalt sulfate. The intention was to investigate the details of the deposition process (and the dissolution process) and the resulting magnetic properties of the Co deposits on graphene. During and after electrodeposition, in-situ magnetic measurements were performed using an (AGFM). These were followed by ex situ morphological analysis of the samples with ΔtDEP 30 and 100 s by atomic force microscopy in the non-contact mode on pristine CVD graphene/SiO2/Si. We demonstrate that it is possible to electrodeposit Co onto graphene, and that in-situ magnetic measurements can also help in understanding details of the deposition process itself. The results show that the Co deposits are ferromagnetic with decreasing coercivity (HC) and demonstrate increasing magnetization on saturation (MSAT) and electric signal proportional to remanence (Mr), as a function of the amount of the electrodeposited Co. It was also found that, after the end of the dissolution process, a certain amount of cobalt remains on the graphene in oxide form (this was confirmed by X-ray photoelectron spectroscopy), as suggested by the magnetic measurements. This oxide tends to exhibit a limited asymptotic amount when cycling through the deposition/dissolution process for increasing deposition times, possibly indicating that the oxidation process is similar to the graphene surface chemistry.
EPDM with Biochar, Carbon Black, Aramid Pulp and Ionic Liquidcompatibilized Aramid Pulp
Vinícius Demétrio da Silva,Micaela Dani Ferrari,Rosmary Nichele Brandalise,Edilson Valmir Benvenutti,Henri Stephan Schrekker,Sandro Campos Amico 한국섬유공학회 2021 Fibers and polymers Vol.22 No.4
Carbon black (CB) is a fossil fuel-derived product widely used as reinforcement in the rubber industry despite itspollution potential and its high energy-demanding production. Biochar, on the other hand, is a renewable source of carbonrecently studied for the partial substitution of CB in elastomeric materials. Aramid pulp/fibers have also been used in avariety of applications in this sector, usually after a surface treatment. In this work, the use of aramid pulp (AP) and biochar inthe preparation of ethylene propylene diene monomer (EPDM) composites and hybrid composites has been studied. The 1-nbutyl-3-methylimidazolium methanesulfonate ionic liquid (IL) was used as compatibilizer in AP, and the rubber-fillerinteraction was studied via thermal, rheometric, mechanical, and swelling analyses. The biochar-EPDM and the referenceCB-EDPM compounds showed similar hardness, modulus at 50 % strain and tear strength results. Among the tested fillers,AP was identified as the most effective to obtain EPDM composites with enhanced properties. A synergistic effect of biocharand IL-treated AP was found, resulting in higher tensile strength for the hybrid formulation (EPDM/Bio05AP05IL)compared to those with just biochar or CB, and reasonable strain at break. In all, the hybrid composites of EPDM reinforcedwith biochar and AP showed the potential to partially or fully replace CB formulations.
Vinícius Bianchi Soares,Luis Antonio Polaci da Silva,Gabriela Martins de Araújo,Fábio Ruiz Simões 대한금속·재료학회 2020 ELECTRONIC MATERIALS LETTERS Vol.16 No.6
In this study, composites based on poly(o-ethoxyaniline), POEA, and its composites grafted with functionalized multiwalledcarbon nanotubes (MWCNT) were obtained by the oxidative in situ chemical polymerization varying the mass ratio ofo-ethoxyaniline:MWCNT of 100:1 and 100:5. POEA and its POEA-MWCNT grafted composites were used to prepare selfassembled(SA) deposited onto indium tin oxide (ITO) substrates with alternating layers of polystyrene sulfonate (PSS). Thestructure and morphology of the samples were characterized by Fourier transform infrared spectroscopy and scanning electronmicroscopy. The SA films were characterized by cyclic voltammetry, UV–Vis and electrochemical impedance spectroscopy(EIS). The EIS results showed expressive decrease of the polarization resistance (Rp), from 13,342 Ω, for POEA/PSS, to 568Ω for POEA-MWCNT(100:1)/PSS (about 23 times lower) and to 240 Ω for POEA-MWCNT(100:5)/PSS film. Consideringthat higher mass proportions of MWCNT can affect the final morphology and the oxidation ratio of POEA chains and aiming strong interactions between the POEA and MWCNT as well the significant reduction of charge transfer resistance, the SA film POEA-MWCNT(100:1)/PSS has potential for future applications as sensors and charge storage devices.