2,159 research outputs found

    Quantum work for sudden quenches in Gaussian random Hamiltonians

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    In the context of nonequilibrium quantum thermodynamics, variables like work behave stochastically. A particular definition of the work probability density function (pdf) for coherent quantum processes allows the verification of the quantum version of the celebrated fluctuation theorems, due to Jarzynski and Crooks, that apply when the system is driven away from an initial equilibrium thermal state. Such a particular pdf depends basically on the details of the initial and final Hamiltonians, on the temperature of the initial thermal state, and on how some external parameter is changed during the coherent process. Using random matrix theory we derive a simple analytic expression that describes the general behavior of the work characteristic function G(u), associated with this particular work pdf for sudden quenches, valid for all the traditional Gaussian ensembles of Hamiltonians matrices. This formula well describes the general behavior of G(u) calculated from single draws of the initial and final Hamiltonians in all ranges of temperatures.Fil: Arrais, Eric G.. Universidade Federal do Rio de Janeiro; BrasilFil: Wisniacki, Diego Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Céleri, Lucas C.. Universidade Federal de Goiás; BrasilFil: De Almeida, Norton G.. Universidade Federal de Goiás; BrasilFil: Roncaglia, Augusto Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Toscano, Fabricio. Universidade Federal do Rio de Janeiro; Brasi

    Slow Protein Dynamics Elicits New Enzymatic Functions by Means of Epistatic Interactions

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    Protein evolution depends on the adaptation of these molecules to different functional challenges. This occurs by tuning their biochemical, biophysical, and structural traits through the accumulation of mutations. While the role of protein dynamics in biochemistry is well recognized, there are limited examples providing experimental evidence of the optimization of protein dynamics during evolution. Here we report an NMR study of four variants of the CTX-M β-lactamases, in which the interplay of two mutations outside the active site enhances the activity against a cephalosporin substrate, ceftazidime. The crystal structures of these enzymes do not account for this activity enhancement. By using NMR, here we show that the combination of these two mutations increases the backbone dynamics in a slow timescale and the exposure to the solvent of an otherwise buried β-sheet. The two mutations located in this β-sheet trigger conformational changes in loops located at the opposite side of the active site. We postulate that the most active variant explores alternative conformations that enable binding of the more challenging substrate ceftazidime. The impact of the mutations in the dynamics is context-dependent, in line with the epistatic effect observed in the catalytic activity of the different variants. These results reveal the existence of a dynamic network in CTX-M β-lactamases that has been exploited in evolution to provide a net gain-of-function, highlighting the role of alternative conformations in protein evolution.Fil: Rossi, María Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Palzkill, Timothy. Baylor College Of Medicine (baylor College Of Medicine);Fil: Almeida, Fabio C L. Universidade Federal do Rio de Janeiro; BrasilFil: Vila, Alejandro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentin

    Catalytic conversion of caffeine into molecules of valuable interest via N-demethylation reaction

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    This work aims to apply catalytic processes to promote the conversion of caffeine into valuable dimethylxanthines via N-demethylation reaction. Thus, we seek to evaluate the products formed and propose the reactions involved and their mechanisms. Reaction conditions were evaluated including different concentrations of Fenton reagent and ascorbic acid to evaluate caffeine oxidation. Theobromine, paraxanthine, and theophylline formation was proven by HPLC-DAD and mass spectrometry analysis evidencing the N-demethylation reactions, via radicals, with about 1 % yield. These results open the way for new N-demethylation reaction routes to be studied with applications for caffeine and other biomolecules in diverse areas such as biochemistry and medicinal chemistry. Application of the Fenton catalysis as alternative to promote the conversion of caffeine in other xanthines by N-demethylation. In this scenario was verified the capability of ascorbic acid in promoting same reaction, both environmentally friendly processes. This work investigates the possibility of using a well known biocompound as a precursor to obtain value added molecules.This study was financially supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001 and by CIMO (UIDB/00690/2020) through FEDER under Program PT2020. In addition, the authors acknowledge Central de Análise e Prospecção Química – CAPQ and Laboratório Central de Biologia Molecular (LCBM), Chemistry Department/UFLA for their technical support. Jose L. Diaz De Tuesta acknowledges the financial support through the program of Atracción al Talento of Comunidad de Madrid (Spain) for the individual research grant 2022-T1/AMB-23946.info:eu-repo/semantics/publishedVersio

    Kinetic insights on wet peroxide oxidation of caffeine using EDTA-functionalized low-cost catalysts prepared from compost generated in municipal solid waste treatment facilities

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    Nowadays, sorted organic fraction of municipal solid waste is typically treated by anaerobic digestion processes, resulting therein a solid stream, further processed to obtain compost, whose production is higher than the existing demand as fertilizer. The current work proposes an alternative strategy for the recovering of compost through the production of low-cost catalysts by calcination (1073 K) and sulfuric acid treatments, followed by sequential functionalization with tetraethyl orthosilicate (TEOS) and ethylenediamine tetraacetic acid (EDTA). Activity and stability of the catalysts are assessed in the wet peroxide oxidation of synthetic wastewater effluents contaminated with caffeine, a model micro-pollutant, achieving its complete removal after 6 h at 353– 383 K and catalyst loads of 0.5–2.5 g L−1. The increase of the catalytic activity of the materials upon functionalization with TEOS and EDTA is demonstrated and a kinetic modeling of caffeine degradation and hydrogen peroxide consumption with the best catalyst is assessed by pseudo-first power-law rate equations.This work was financially supported by project ‘‘VALORCOMP - Valorización de compost y otros desechos procedentes de la fracción orgánica de los residuos municipales’’, 0119_VALORCOMP_2_P, through FEDER under Program INTERREG; and CIMO (UIDB/00690/2020) through FEDER under Program PT2020.info:eu-repo/semantics/publishedVersio

    Days out of role due to common physical and mental conditions in Portugal: results from the WHO World Mental Health Survey

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    Funding: The Portuguese Mental Health Study was carried out by the Department of Mental Health, NOVA Medical School, NOVA University of Lisbon, with collaboration of the CESOP – Portuguese Catholic University and was funded by the Champalimaud Foundation, the Gulbenkian Foundation, the Foundation for Science and Technology (FCT) and the Ministry of Health. The Portuguese Mental Health Study was carried out in conjunction with the World Health Organization WMH Survey Initiative which is supported by the National Institute of Mental Health (NIMH; R01 MH070884), the John D. and Catherine T. MacArthur Foundation, the Pfizer Foundation, the U.S. Public Health Service (R13-MH066849, R01-MH069864 and R01 DA016558), the Fogarty International Center (FIRCA R03-TW006481), the Pan American Health Organization, Eli Lilly and Company, OrthoMcNeil Pharmaceutical, GlaxoSmithKline and Bristol-Myers Squibb.publishersversionpublishe

    Quantitative And Qualitative Analysis Of Microorganisms In Root-filled Teeth With Persistent Infection: Monitoring Of The Endodontic Retreatment.

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    The aim of this study was to investigate in vivo microorganisms detected in root-filled teeth with post-treatment apical periodontitis and quantify colony-forming units (CFU) during endodontic retreatment. Fifteen root-filled teeth had their previous gutta-percha removed and were randomly instrumented before being divided into three groups and medicated with either [Ca(OH)2 + 2% CHX gel], [Ca(OH)2 + 0.9% NaCl] or 2% CHX gel. Samples were taken after removal of gutta-percha (S1), after chemomechanical preparation using 2% CHX gel (S2), and after inter-appointment dressing (S3) for 7 or 14 days later. Cultivable bacteria recovered from infected root canals at the three stages were counted and identified by means of culture and PCR assay (16S rDNA). Quantitative data were statistically analyzed by using Mann-Whitney test in which pairs of groups were compared (P < 0.05). CFU counts decreased significantly from S1 to S2 (P < 0.05). No significant difference was found between S2 and S3 (P = 0.3093) for all three experimental groups. Chemomechanical preparation and intra-canal dressing promoted significant median reductions of 99.61% and 99.57%, respectively, in the number of bacteria compared to S1 samples. A total of 110 cultivable isolates were recovered by culture technique from 32 different species and 7 different genera. Out of the 13 target species-specific primer of bacteria analyzed, 11 were detected during endodontic retreatment. The great majority of taxa found in post-treatment samples were Gram-positive bacteria, although Gram-negative bacteria were found by molecular methods. Moreover, our results showed that gutta-percha removal and chemomechanical preparation are effective for root canal disinfection, whereas additional intra-canal dressing did not improve disinfection.7302-

    Quality Assessment of Photoplethysmography Signals For Cardiovascular Biomarkers Monitoring Using Wearable Devices

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    Photoplethysmography (PPG) is a non-invasive technology that measures changes in blood volume in the microvascular bed of tissue. It is commonly used in medical devices such as pulse oximeters and wrist worn heart rate monitors to monitor cardiovascular hemodynamics. PPG allows for the assessment of parameters (e.g., heart rate, pulse waveform, and peripheral perfusion) that can indicate conditions such as vasoconstriction or vasodilation, and provides information about microvascular blood flow, making it a valuable tool for monitoring cardiovascular health. However, PPG is subject to a number of sources of variations that can impact its accuracy and reliability, especially when using a wearable device for continuous monitoring, such as motion artifacts, skin pigmentation, and vasomotion. In this study, we extracted 27 statistical features from the PPG signal for training machine-learning models based on gradient boosting (XGBoost and CatBoost) and Random Forest (RF) algorithms to assess quality of PPG signals that were labeled as good or poor quality. We used the PPG time series from a publicly available dataset and evaluated the algorithm s performance using Sensitivity (Se), Positive Predicted Value (PPV), and F1-score (F1) metrics. Our model achieved Se, PPV, and F1-score of 94.4, 95.6, and 95.0 for XGBoost, 94.7, 95.9, and 95.3 for CatBoost, and 93.7, 91.3 and 92.5 for RF, respectively. Our findings are comparable to state-of-the-art reported in the literature but using a much simpler model, indicating that ML models are promising for developing remote, non-invasive, and continuous measurement devices.Comment: 9 page

    Effects of cannabinoid drugs on the deficit of prepulse inhibition of startle in an animal model of schizophrenia: the SHR strain

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    Clinical and neurobiological findings suggest that the cannabinoids and the endocannabinoid system may be implicated in the pathophysiology and treatment of schizophrenia. We described that the spontaneously hypertensive rats (SHR) strain presents a schizophrenia behavioral phenotype that is specifically attenuated by antipsychotic drugs, and potentiated by proschizophrenia manipulations. Based on these findings, we have suggested this strain as an animal model of schizophrenia. the aim of this study was to evaluate the effects of cannabinoid drugs on the deficit of prepulse inhibition (PPI) of startle, the main paradigm used to study sensorimotor gating impairment related to schizophrenia, presented by the SHR strain. the following drugs were used: (1) WIN55212,2 (cannabinoid agonist), (2) rimonabant (CB1 antagonist), (3) AM404 (anandamide uptake inhibitor), and (4) cannabidiol (CBD; indirect CB1/CB2 receptor antagonist, among other effects). VVistar rats (VVRs) and SHRs were treated with vehicle (VEH) or different doses of WIN55212 (0.3, 1, or 3 mg/kg), rimonabant (0.75, 1.5, or 3 mg/kg), AM404 (1, 5, or 10 mg/kg), or CBD (15, 30, or 60 mg/kg). VEH-treated SHRs showed a decreased PPI when compared to VVRs. This PPI deficit was reversed by 1 mg/kg WIN and 30 mg/kg CBD. Conversely, 0.75 mg/kg rimonabant decreased PPI in SHR strain, whereas AM404 did not modify it. Our results reinforce the role of the endocannabinoid system in the sensorimotor gating impairment related to schizophrenia, and point to cannabinoid drugs as potential therapeutic strategies.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo, Dept Pharmacol, BR-04039032 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Psychiat, Lab Interdisciplinar Neurociencias Clin, BR-04039032 São Paulo, BrazilUniv São Paulo, Dept Neurosci & Behav, BR-14049 Ribeirao Preto, BrazilNatl Council Sci & Technol Dev, Natl Inst Sci & Technol Translat Med, Ribeirao Preto, BrazilUniversidade Federal de São Paulo, Dept Pharmacol, BR-04039032 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Psychiat, Lab Interdisciplinar Neurociencias Clin, BR-04039032 São Paulo, BrazilFAPESP: FAPESP - 2010/07994-3Web of Scienc

    Squaraine dyes derived from indolenine and benzo[e]indole as potential fluorescent probes for HSA detection and antifungal agents

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    Four squaraine dyes derived from 2,3,3-trimethylindolenine and 1,1,2-trimethyl-1H-benzo[e]indole with different combinations of barbituric groups attach to the central ring, having ester groups and alkyl chains in the nitrogen atoms of heterocyclic rings were synthesized. These dyes were fully characterized and their photophysical behavior was studied in ethanol and phosphate-buffered saline solution. Absorption and emission bands between 631 and 712 nm were detected, with the formation of aggregates in aqueous media, which is typical of this class of dyes. Tests carried out with 1,3-diphenylisobenzofuran allowed us to verify the ability of the dyes to produce singlet oxygen. The interaction of synthesized dyes with human serum albumin (HSA) was also evaluated, being demonstrated a linear correlation between fluorescence intensity and protein concentration. The antifungal potential of the dyes against the yeast Saccharomyces cerevisiae was evaluated using a broth microdilution assay. In order to test the photosensitizing capacity of the synthesized dyes, tests were carried out in the dark and with irradiation, using a custom-built light-emitting diode that emits close to the absorption wavelength of the studied dyes. The results showed that the interaction of dyes with HSA and the antifungal activity depends on the different structural modifications of the dyes.We thanks to Fundação para a Ciência e Tecnologia (FCT), Comissão de Coordenação e Desenvolvimento Regional do Norte (CCDR-N) and FEDER (European Fund for Regional Development)-COMPETEQREN-EU for financial support to the research centers CQ/UM (UIDB/00686/2020), CBMA (UID/BIA/04050/2020), CQ/VR (UID/QUI/UI0616/2019) and CICSUBI (POCI-01-0145-FEDER-007491), as well as PhD grants to V.S.D.G. (UMINHO/BD/43/2016) and J.C.C.F. (SFRH/BD/133207/2017)
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