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A subgroup of light-driven sodium pumps with an additional Schiff base counterion. Nat Commun 2024; 15:3119. [PMID: 38600129 PMCID: PMC11006869 DOI: 10.1038/s41467-024-47469-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 04/01/2024] [Indexed: 04/12/2024] Open
Abstract
Light-driven sodium pumps (NaRs) are unique ion-transporting microbial rhodopsins. The major group of NaRs is characterized by an NDQ motif and has two aspartic acid residues in the central region essential for sodium transport. Here we identify a subgroup of the NDQ rhodopsins bearing an additional glutamic acid residue in the close vicinity to the retinal Schiff base. We thoroughly characterize a member of this subgroup, namely the protein ErNaR from Erythrobacter sp. HL-111 and show that the additional glutamic acid results in almost complete loss of pH sensitivity for sodium-pumping activity, which is in contrast to previously studied NaRs. ErNaR is capable of transporting sodium efficiently even at acidic pH levels. X-ray crystallography and single particle cryo-electron microscopy reveal that the additional glutamic acid residue mediates the connection between the other two Schiff base counterions and strongly interacts with the aspartic acid of the characteristic NDQ motif. Hence, it reduces its pKa. Our findings shed light on a subgroup of NaRs and might serve as a basis for their rational optimization for optogenetics.
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A Single Amino Acid Able to Promote High-Temperature Ring-Opening Polymerization by Dual Activation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2308956. [PMID: 38348541 DOI: 10.1002/advs.202308956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/12/2024] [Indexed: 04/25/2024]
Abstract
Amino acids are indispensable compounds in the body, performing several biological processes that enable proper functioning. In this work, it is demonstrated that a single amino acid, taurine, is also able to promote the ring-opening polymerization (ROP) of several cyclic monomers under industrially relevant conditions. It is shown that the unique zwitterionic structure of taurine, where the negatively charged sulfonic acid group and the protonated amine group are separated by two methylene groups, not only provides high thermal stability but also leads to a dual activation mechanism, which is corroborated by quantum mechanical calculations. This unique mechanism allows for the synthesis of polylactide of up to 50 kDa in bulk at 180 °C with good end-group fidelity using a highly abundant catalyst. Furthermore, cytotoxicity tests confirm that PLLA synthesized with taurine is non-toxic. Moreover, it is demonstrated that the presence of taurine does not have any detrimental effect on the thermal stability of polylactide, and therefore polymers can be used directly without any post-polymerization purification. It is believed that the demonstration that a simple structure composed of a single amino acid can promote polymerization can bring a paradigm shift in the preparation of polymers.
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Systematic assessment of wastewater resource circularity and sustainable value creation. WATER RESEARCH 2024; 251:121141. [PMID: 38246082 DOI: 10.1016/j.watres.2024.121141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 01/12/2024] [Accepted: 01/14/2024] [Indexed: 01/23/2024]
Abstract
The circular use of wastewater has attracted significant attention in recent years. However, there is a lack of universal definitions and measurement tools that are required to achieve the circular economy's full potential. Therefore, a methodology was developed using three indicator typologies, namely resource flow, circular action, and sustainability indicators, to facilitate a robust and holistic circularity assessment. The method uses value propositions to integrate the assessment of intrinsic circularity performance with consequential circularity impacts, by quantifying sustainable value creation (using techniques such as life cycle assessment or cost-benefit analysis). Assessment method capabilities were exhibited by applying the defined steps to a wastewater treatment plant, comparing conventional and novel photobioreactor technologies. The resource flow indicator taxonomy results highlight improved outflow circularity, renewable energy usage, and economic efficiency of the novel system. Action indicators revealed that the photobioreactor technology was successful at achieving its defined circular goals. Lastly, sustainability indicators quantified a reduction of carbon footprint by two thirds and eutrophication by 41%, a M€ 0.5 per year increase of economic value, and that disability adjusted life year impacts are 58% lower. This supports that improving wastewater system circularity using photobioreactor technology results in environmental, economic, and social value for stakeholders.
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Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment. PHYSICAL REVIEW LETTERS 2024; 132:065102. [PMID: 38394591 DOI: 10.1103/physrevlett.132.065102] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 01/03/2024] [Indexed: 02/25/2024]
Abstract
On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.
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Self-assembled three-dimensional hydrogels based on graphene derivatives and cerium oxide nanoparticles: scaffolds for co-culture of oligodendrocytes and neurons derived from neural stem cells. NANOSCALE 2023; 15:4488-4505. [PMID: 36753326 DOI: 10.1039/d2nr06545b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Stem cell-based therapies have shown promising results for the regeneration of the nervous system. However, the survival and integration of the stem cells in the neural circuitry is suboptimal and might compromise the therapeutic outcomes of this approach. The development of functional scaffolds capable of actively interacting with stem cells may overcome the current limitations of stem cell-based therapies. In this study, three-dimensional hydrogels based on graphene derivatives and cerium oxide (CeO2) nanoparticles are presented as prospective supports allowing neural stem cell adhesion, migration and differentiation. The morphological, mechanical and electrical properties of the resulting hydrogels can be finely tuned by controlling several parameters of the self-assembly of graphene oxide sheets, namely the amount of incorporated reducing agent (ascorbic acid) and CeO2 nanoparticles. The intrinsic properties of the hydrogels, as well as the presence of CeO2 nanoparticles, clearly influence the cell fate. Thus, stiffer adhesion substrates promote differentiation to glial cell lineages, while softer substrates enhance mature neuronal differentiation. Remarkably, CeO2 nanoparticle-containing hydrogels support the differentiation of neural stem cells to neuronal, astroglial and oligodendroglial lineage cells, promoting the in vitro generation of nerve tissue grafts that might be employed in neuroregenerative cell therapies.
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Addressing high cervical cancer rates in the Rio Grande Valley along the Texas-Mexico border: a community-based initiative focused on education, patient navigation, and medical provider training/telementoring. Perspect Public Health 2023; 143:22-28. [PMID: 34130548 DOI: 10.1177/1757913921994610] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
AIMS Cervical cancer incidence and mortality rates are approximately 55% higher in the Rio Grande Valley (RGV) along the Texas-Mexico border compared with the average rates in the US. Our aim was to improve cervical cancer prevention efforts in the RGV through a comprehensive multilevel intervention initiative focused on community education, patient navigation, and training of local providers. METHODS We initiated a program in the RGV which consisted of (1) community education, (2) patient navigation, and (3) a training/mentoring program for local medical providers including hands-on training courses coupled with telementoring using Project ECHO® (Extension for Community Health Outcomes). We assessed the number of women undergoing cervical cancer screening, diagnosis, and treatment at three participating clinics caring for underserved women in the region. RESULTS From November 2014 to October 2018, 14,846 women underwent cervical cancer screening. A total of 2030 (13.7%) women underwent colposcopy for abnormal results (179% increase over baseline) and 453 women underwent loop electrosurgical excision procedures (LEEPs) for treatment of cervical dysplasia. Invasive cancer was diagnosed in 39 women who were navigated to a gynecologic oncologist for treatment. Seven local medical providers were trained to perform colposcopy and/or LEEP. Project ECHO telementoring videoconferences were held every 2 weeks for a total 101 sessions with an average of 22 participants per session and a total of 180 patient cases presented and discussed. CONCLUSIONS Our program led to a large number of women undergoing diagnosis and treatment of cervical dysplasia in the RGV. If sustained, we anticipate these efforts will decrease cervical cancer rates in the region. The program is currently being expanded to additional underserved areas of Texas and globally to low- and middle-income countries.
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EP08.02-102 Feasibility and Clinical Utility of ctDNA for Detection of Sensitizing and Resistance EGFR Mutations in Patients with Non-small Cell Lung Cancer. J Thorac Oncol 2022. [DOI: 10.1016/j.jtho.2022.07.785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment. PHYSICAL REVIEW LETTERS 2022; 129:075001. [PMID: 36018710 DOI: 10.1103/physrevlett.129.075001] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 06/24/2022] [Accepted: 07/06/2022] [Indexed: 06/15/2023]
Abstract
For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.
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Crystallization-Induced Gelling as a Method to 4D Print Low-Water-Content Non-isocyanate Polyurethane Hydrogels. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2021; 33:7194-7202. [PMID: 34602744 PMCID: PMC8482781 DOI: 10.1021/acs.chemmater.1c00913] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Indexed: 06/13/2023]
Abstract
The use of three-dimensional (3D) printable hydrogels for biomedical applications has attracted considerable attention as a consequence of the ability to precisely define the morphology of the printed object, allowing patients' needs to be targeted. However, the majority of hydrogels do not possess suitable mechanical properties to fulfill an adequate rheological profile for printability, and hence, 3D printing of cross-linked networks is challenging and normally requires postprinting modifications to obtain the desired scaffolds. In this work, we took advantage of the crystallization process of poly(ethylene glycol) to print non-isocyanate poly(hydroxyurethane) hydrogels with tunable mechanical properties. As a consequence of the crystallization process, the hydrogel modulus can be tuned up to 3 orders of magnitude upon heating up to 40 °C, offering an interesting strategy to directly 3D-print hydrogels without the need of postprinting cross-linking. Moreover, the absence of any toxicity makes these materials ideal candidates for biomedical applications.
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Mechanisms of instantaneous inactivation of SARS-CoV-2 by silicon nitride bioceramic. Mater Today Bio 2021; 12:100144. [PMID: 34632359 PMCID: PMC8485720 DOI: 10.1016/j.mtbio.2021.100144] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/20/2021] [Accepted: 09/24/2021] [Indexed: 12/23/2022] Open
Abstract
The hydrolytic processes occurring at the surface of silicon nitride (Si3N4) bioceramic have been indicated as a powerful pathway to instantaneous inactivation of SARS-CoV-2 virus. However, the virus inactivation mechanisms promoted by Si3N4 remain yet to be elucidated. In this study, we provide evidence of the instantaneous damage incurred on the SARS-CoV-2 virus upon contact with Si3N4. We also emphasize the safety characteristics of Si3N4 for mammalian cells. Contact between the virions and micrometric Si3N4 particles immediately targeted a variety of viral molecules by inducing post-translational oxidative modifications of S-containing amino acids, nitration of the tyrosine residue in the spike receptor binding domain, and oxidation of RNA purines to form formamidopyrimidine. This structural damage in turn led to a reshuffling of the protein secondary structure. These clear fingerprints of viral structure modifications were linked to inhibition of viral functionality and infectivity. This study validates the notion that Si3N4 bioceramic is a safe and effective antiviral compound; and a primary antiviral candidate to replace the toxic and allergenic compounds presently used in contact with the human body and in long-term environmental sanitation.
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Smart Layer-by-Layer Polymeric Microreactors: pH-Triggered Drug Release and Attenuation of Cellular Oxidative Stress as Prospective Combination Therapy. ACS APPLIED MATERIALS & INTERFACES 2021; 13:18511-18524. [PMID: 33861060 PMCID: PMC9161222 DOI: 10.1021/acsami.1c01450] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/02/2021] [Indexed: 05/06/2023]
Abstract
Polymer capsules fabricated via the layer-by-layer (LbL) approach have emerged as promising biomedical systems for the release of a wide variety of therapeutic agents, owing to their tunable and controllable structure and the possibility to include several functionalities in the polymeric membrane during the fabrication process. However, the limitation of the capsules with a single functionality to overcome the challenges involved in the treatment of complex pathologies denotes the need to develop multifunctional capsules capable of targeting several mediators and/or mechanisms. Oxidative stress is caused by the accumulation of reactive oxygen species [e.g., hydrogen peroxide (H2O2), hydroxyl radicals (•OH), and superoxide anion radicals (•O2-)] in the cellular microenvironment and is a key modulator in the pathology of a broad range of inflammatory diseases. The disease microenvironment is also characterized by the presence of proinflammatory cytokines, increased levels of matrix metalloproteinases, and acidic pH, all of which could be exploited to trigger the release of therapeutic agents. In the present work, multifunctional capsules were fabricated via the LbL approach. Capsules were loaded with an antioxidant enzyme (catalase) and functionalized with a model drug (doxorubicin), which was conjugated to an amine-containing dendritic polyglycerol through a pH-responsive linker. These capsules efficiently scavenge H2O2 from solution, protecting cells from oxidative stress, and release the model drug in acidic microenvironments. Accordingly, in this work, a polymeric microplatform is presented as an unexplored combinatorial approach applicable for multiple targets of inflammatory diseases, in order to perform controlled spatiotemporal enzymatic reactions and drug release in response to biologically relevant stimuli.
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Clinical and microbiological characteristics of paracoccidioidomycosis in patients with AIDS in Buenos Aires, Argentina. Med Mycol 2020; 58:22-29. [PMID: 30874811 DOI: 10.1093/mmy/myz021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 02/10/2019] [Accepted: 02/14/2019] [Indexed: 12/12/2022] Open
Abstract
Paracoccidioidomycosis (Pm) is a systemic disease, endemic in the American continent. There are two different clinical forms, the infant-juvenile or subacute form (PmS) and the chronic adult form (PmC). The human immunodeficiency virus (HIV) associated paracoccidioidomycosis (PmHIV) shares characteristics with both of the previously mentioned forms. The objective of this work was to describe the epidemiological, clinical and laboratory features of the PmHIV and to compare them with the ones of PmS and the PmC. A retrospective analysis of 119 patients with paracoccidioidomycosis was performed. Ninety four suffered the chronic form, 11 the subacute one and 14 were coinfected with HIV. Patients with PmHIV presented a CD4+ T lymphocytes median of 70.5 cells/μl, 71.4% had fever, 64.3% had a miliary pattern on the chest radiography, 64.3% had hepatosplenomegaly, 64.3% had mucosal lesions and 50% had skin lesions. One patient died during his hospitalization. The clinical presentation of Pm in patients with HIV resembled the subacute form with fever, hepatomegaly and skin lesions. However, they also tended to present mucosal lesions, positive serology for Pm and pulmonary parenchyma lesions as usually seen in PmC (9/14 PmHIV patients had overlapping features, while 4/14 PmHIV patients clinically resembled PmS and 1/14 PmC). The incidence of Pm has not changed with the burden of AIDS as it has happened with other fungal infections but it appears clinically different from the classic clinical forms of the disease.
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P2.04-22 Programmed Death 1-mRNA Expression Predicts Benefit to Anti-PD1 Monotherapy in a Prospective Cohort of Advanced NSCLC. J Thorac Oncol 2019. [DOI: 10.1016/j.jtho.2019.08.1527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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P3612Validation of Charlson Comorbidity Index to predict adverse events in elderly patients with Atrial Fibrillation and Acute Coronary Syndrome: an analysis from LONGEVO-SCA Registry. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz745.0471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
Aging is frequently characterized by the coexistence of several comorbid conditions that increase the adverse prognosis during hospitalization. There are few scores to analyze the impact of comorbidities in prognosis. Charlson Comorbidity Index (CCI). This score evaluates the burden of comorbidity in general population but the influence within cardiac diseases is unknown.
Purpose
The aim of this study was to analyze the relationship of CCI in adverse outcomes at short-term follow-up in elderly patients with atrial fibrillation (AF) admitted after an acute coronary syndrome (ACS).
Methods
The prospective multicenter LONGEVO-SCA included unselected elderly patients hospitalized after non-STACS. In this substudy, we analyze the influence of comorbidities in elderly AF patients, comparing high quartiles of CCI (Q3-Q4: high burden of comorbidities) to low quartiles (Q1-Q2) and the predictive performance of adverse events at 6 months follow-up of CCI.
Results
We analyzed 531 patients (mean age 84.4±3.6 years; 322 (60.6%) male). 128 (24.1%) had AF diagnosis. 91 (71.1%) patients were classified into Q1-Q2 and 37 (28.9%) patients into Q3-Q4. We analyzed the association of clinical factors and adverse events and, after Cox multivariate regression analysis, CCI was independently associated with readmissions [HR 1.19, 95% CI (1.02–1.39); p=0.020) and all-cause mortality [HR 1.32, 95% CI (1.09–1.59); p=0.003]. Patients into Q3-Q4 had higher risk of mortality than patients into Q1-Q2 [HR 5.52, 95% CI (1.01–30.3); p=0.049]. Kaplan Meier analysis showed that AF patients into Q3-Q4 had significantly worse prognosis during the follow-up with high risk of all-cause mortality (p=0.034) and readmissions due to ACS (p=0.027). We observed good predictive performance of CCI for mortality (c-statistic 0.705; p<0.001) and modest predictive performance for readmissions (c-statistic 0.627; p<0.001).
Event Free Survival according Charlson
Conclusions
Patients into high quartiles of CCI had higher risk of adverse events during the follow-up. CCI was an independent predictor of all-cause mortality and readmissions in elderly patients. Indeed, this is the first time to validate CCI to predict adverse events in AF patients with ACS.
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Les prescriptions de linézolide sont-elles toujours pertinentes dans notre établissement ? Med Mal Infect 2019. [DOI: 10.1016/j.medmal.2019.04.155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Pertinence de l’usage de la daptomycine dans un centre hospitalier universitaire : étude rétrospective monocentrique. Med Mal Infect 2019. [DOI: 10.1016/j.medmal.2019.04.153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Perspectives on cervical cancer screening and prevention: challenges faced by providers and patients along the Texas–Mexico border. Perspect Public Health 2018; 139:199-205. [DOI: 10.1177/1757913918793443] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Background:The Rio Grande Valley (RGV) and Laredo regions located along the Texas–Mexico border consist of seven counties with a population of approximately 1.5 million people and a high uninsured rate (33.5%). Cervical cancer mortality in these border counties is approximately 30% higher than the rest of Texas. The RGV and Laredo areas were studied to better understand the state of access to cervical cancer prevention services along the Texas–Mexico border.Methods:Data on the population served and the services provided were analyzed to determine the gap between cervical cancer screenings recommended versus those received. Through interviews, we gathered the perspectives of 16 local stakeholders regarding cervical cancer screening for underserved individuals in the region.Findings:It is estimated that 69,139 uninsured women aged 21–64 years in the RGV/Laredo per year are recommended to undergo cervical cancer screening with Papanicolaou (Pap) and/or human papillomavirus (HPV) testing, but only 8941 (12.9%) Pap tests are being performed by the Federally Qualified Health Center (FQHC) serving uninsured women in these regions. Systemic barriers identified include insufficient provider clinical capacity, the high cost of healthcare, and uncertainty about government funding sources. Patient barriers identified include inadequate knowledge on navigating the local healthcare system, low health literacy, lack of money and childcare, an inability to miss work, limited transportation, and fear of deportation.Conclusion:Decreasing the disparity between cervical cancer screening services provided and those recommended requires addressing the barriers, identified by local experts, which prevent uninsured women from accessing care. These challenges are being addressed through ongoing programs and collaborations.
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Suivi des antibiotiques « critiques » par une Équipe opérationnelle d’infectiologie : bilan à un an. Med Mal Infect 2018. [DOI: 10.1016/j.medmal.2018.04.159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Test of Fibre Bragg Gratings samples under High Fast Neutrons Fluence. EPJ WEB OF CONFERENCES 2018. [DOI: 10.1051/epjconf/201817004004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Optical fibre sensors (OFS) are worthy of interest for measurements in nuclear reactor thanks to their unique features, particularly compact size and remote multi-point sensing for some of them. But besides non negligible constraints associated with the high temperature environment of the experiments of interest, it is well known that the performances of OFS can be severely affected by high level of radiations. The Radiation Induced Attenuation (RIA) in the fibre is probably most known effect, which can be to some extent circumvented by using rad hard fibres to limit the dynamic loss. However, when the fast neutron fluence reaches 1018 to 1019 n/cm2, the density and index variations associated to structural changes may deteriorate drastically the performances of OFS even if they are based on rad hard fibres, by causing direct errors in the measurements of temperature and/or strain changes. The aim of the present study is to access the effect of nuclear radiations on the Fabry Perot (FP) and of Fibre Bragg Grating (FBG) sensors through the comparison of measurements made on these OFS - or part of them - before and after irradiation [1].
In the context of development of OFS for high irradiation environment and especially for Material Testing Reactors (MTRs), Sake 2 experiment consists in an irradiation campaign at high level of gamma and neutron fluxes conducted on samples of fibre optics – bare or functionalised with FBG. The irradiation was performed at two levels of fast neutron fluence: 1 and 3.1019 n/cm2 (E>1MeV), at 250°± 25°C, in the SCK•CEN BR2 reactor (Mol Belgium). An irradiation capsule was designed to allow irradiation at the specified temperature without active control. The neutron fluence was measured with activation dosimeters and the results were compared with MCPN computations. Investigation of bare samples gives information on the density changes, while for the FBGs both density and refractive index perturbation are involved. Some results for bare fibres were reported recently. In this paper, we will focus on the measurements made on FBGs that have been manufactured by different laboratories on SMF 28 fibers: CEA, University of St-Etienne and University of Mons. Tested gratings have been written using various conditions (type of fibre, of laser, writing wavelength, power density, post writing thermal annealing,…), leading to various behaviours after Sake 2 irradiation. Bragg wavelength and reflectivity have been measured before and after irradiation thanks to a special mounting at the same temperature. It appears that a change in the shape after irradiation of the Bragg peak disturb the retrieval of the Bragg wavelength.
The measurements show that for nearly all gratings the Bragg peak remains visible after the irradiation, and that Radiation Induced Bragg Wavelength Shifts (RI-BWSs) vary from few pm (equivalent to an error of less than 1°C for a temperature sensor) to nearly 1 nm (equivalent to 100°C) depending of the FBG types. High RI-BWSs could indeed be expected when considering the huge refractive index variation and compaction of the bare fibre samples that have been measured by other techniques. Post writing thermal annealing is confirmed as a key parameter in order to obtain a more radiation tolerant FBG. Our results show that specific annealing regimes allow making FGBs suitable to perform temperature measurements in a MTR experiment.
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Real time monitoring of water level and temperature in storage fuel pools through optical fibre sensors. Sci Rep 2017; 7:8766. [PMID: 28821768 PMCID: PMC5562826 DOI: 10.1038/s41598-017-08853-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 07/18/2017] [Indexed: 12/01/2022] Open
Abstract
We present an innovative architecture of a Rayleigh-based optical fibre sensor for the monitoring of water level and temperature inside storage nuclear fuel pools. This sensor, able to withstand the harsh constraints encountered under accidental conditions such as those pointed-out during the Fukushima-Daiichi event (temperature up to 100 °C and radiation dose level up to ~20 kGy), exploits the Optical Frequency Domain Reflectometry technique to remotely monitor a radiation resistant silica-based optical fibre i.e. its sensing probe. We validate the efficiency and the robustness of water level measurements, which are extrapolated from the temperature profile along the fibre length, in a dedicated test bench allowing the simulation of the environmental operating and accidental conditions. The conceived prototype ensures an easy, practical and no invasive integration into existing nuclear facilities. The obtained results represent a significant breakthrough and comfort the ability of the developed system to overcome both operating and accidental constraints providing the distributed profiles of the water level (0–to–5 m) and temperature (20–to–100 °C) with a resolution that in accidental condition is better than 3 cm and of ~0.5 °C respectively. These new sensors will be able, as safeguards, to contribute and reinforce the safety in existing and future nuclear power plants.
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Chemically driven tetragonal-to-monoclinic polymorphic transformation in retrieved ZTA femoral heads from dual mobility hip implants. J Mech Behav Biomed Mater 2015; 56:195-204. [PMID: 26708254 DOI: 10.1016/j.jmbbm.2015.11.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/23/2015] [Accepted: 11/30/2015] [Indexed: 02/04/2023]
Abstract
Two short-term (two and nine months) retrieved zirconia-toughened alumina (ZTA) femoral heads and nine pristine femoral heads from the same manufacturer have been investigated with respect to their surface stability by means of confocal Raman spectroscopy. Quantitative estimations of monoclinic volume fraction have been carried out in both non-wear and main wear zones of the retrieved heads, which invariantly showed high volume fractions of monoclinic polymorph. In-depth (sub-surface) profiles, non-destructively collected in the main wear zones with the Raman probe in confocal configuration, indeed confirmed that polymorphic transformation was extended down to 100μm below the bearing surface of the femoral heads. Acceleration of tetragonal-to-monoclinic transformation rate leads to unexpectedly high fractions of monoclinic phase within very short-term in-vivo exposures. Phase transformation in-vivo is much more marked than what one could actually predict according to simply simulating a hydrothermal environment in-vitro and could not be simply ascribed to the mechanical stress fields generated during normal service at the bearing surface. Instead, the chemical consequences of metal contamination on the ZTA femoral head surface are shown to play the most detrimental role in phase destabilization.
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Radiation effects on optical frequency domain reflectometry fiber-based sensor. OPTICS LETTERS 2015; 40:4571-4574. [PMID: 26469566 DOI: 10.1364/ol.40.004571] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We investigate the radiation effects on germanosilicate optical fiber acting as the sensing element of optical frequency domain reflectometry devices. Thanks to a new setup permitting to control temperature during irradiation, we evaluate the changes induced by 10 keV x rays on their Rayleigh response up to 1 MGy in a temperature range from -40°C up to 75°C. Irradiation at fixed temperature points out that its measure is reliable during both irradiation and the recovery process. Mixed temperature and radiation measurements show that changing irradiation temperature leads to an error in distributed measurements that depends on the calibration procedure. These results demonstrate that Rayleigh-based optical fiber sensors are very promising for integration in harsh environments.
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Vulnerability of OFDR-based distributed sensors to high γ-ray doses. OPTICS EXPRESS 2015; 23:18997-19009. [PMID: 26367563 DOI: 10.1364/oe.23.018997] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Vulnerability of Optical Frequency Domain Reflectometry (OFDR) based sensors to high γ-ray doses (up to 10 MGy) is evaluated with a specific issue of a radiation-hardened temperature and strain monitoring system for nuclear industry. For this, we characterize the main radiation effects that are expected to degrade the sensor performances in such applicative domain: the radiation-induced attenuation (RIA), the possible evolution with the dose of the Rayleigh scattering phenomenon as well as its dependence on temperature and strain. This preliminary investigation is done after the irradiation and for five different optical fiber types covering the range from radiation-hardened fibers to highly radiation sensitive ones. Our results show that at these high dose levels the scattering mechanism at the basis of the used technique for the monitoring is unaffected (changes below 5%), authorizing acceptable precision on the temperature or strain measurements. RIA has to be considered as it limits the sensing range. From our vulnerability study, the OFDR sensors appear as promising candidates for nuclear industry even at doses as high as 10 MGy.
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Electropyroelectric technique: A methodology free of fitting procedures for thermal effusivity determination in liquids. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:064902. [PMID: 26133860 DOI: 10.1063/1.4922520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This paper describes an alternative methodology to determine the thermal effusivity of a liquid sample using the recently proposed electropyroelectric technique, without fitting the experimental data with a theoretical model and without having to know the pyroelectric sensor related parameters, as in most previous reported approaches. The method is not absolute, because a reference liquid with known thermal properties is needed. Experiments have been performed that demonstrate the high reliability and accuracy of the method with measurement uncertainties smaller than 3%.
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Radiation tolerant fiber Bragg gratings for high temperature monitoring at MGy dose levels. OPTICS LETTERS 2014; 39:5313-5316. [PMID: 26466259 DOI: 10.1364/ol.39.005313] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report a method for fabricating fiber Bragg gratings (FBG) resistant to very severe environments mixing high radiation doses (up to 3 MGy) and high temperatures (up to 230°C). Such FBGs have been written in two types of radiation resistant optical fibers (pure-silica and fluorine-doped cores) by exposures to a 800 nm femtosecond IR laser at power exceeding 500 mW and then subjected to a thermal annealing treatment of 15 min at 750°C. Under radiation, our study reveals that the radiation induced Bragg wavelength shift (BWS) at a 3 MGy dose is strongly reduced compared to responses of FBGs written with nonoptimized conditions. The BWS remains lower than 10 pm for temperatures of irradiation ranging from 25°C to 230°C without noticeable decrease of the FBG peak amplitude. For an applicative point of view, this radiation induced BWS corresponds to an additional error on the temperature measurements lower than 1.5°C, opening the way to the development of radiation-tolerant multi-point temperature sensors for nuclear industry.
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Experimental validation of a novel compact focusing scheme for future energy-frontier linear lepton colliders. PHYSICAL REVIEW LETTERS 2014; 112:034802. [PMID: 24484144 DOI: 10.1103/physrevlett.112.034802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Indexed: 06/03/2023]
Abstract
A novel scheme for the focusing of high-energy leptons in future linear colliders was proposed in 2001 [P. Raimondi and A. Seryi, Phys. Rev. Lett. 86, 3779 (2001)]. This scheme has many advantageous properties over previously studied focusing schemes, including being significantly shorter for a given energy and having a significantly better energy bandwidth. Experimental results from the ATF2 accelerator at KEK are presented that validate the operating principle of such a scheme by demonstrating the demagnification of a 1.3 GeV electron beam down to below 65 nm in height using an energy-scaled version of the compact focusing optics designed for the ILC collider.
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Hybrid diffusive/PVD treatments to improve the tribological resistance of Ti-6Al-4V. Biomed Mater Eng 2014; 24:581-92. [DOI: 10.3233/bme-130845] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Abstract P6-06-41: Non-palpable tumor is a surrogate factor for longer disease free survival in early breast cancer: Evaluation of a 23 years-Venezuelan cohort. Cancer Res 2013. [DOI: 10.1158/0008-5472.sabcs13-p6-06-41] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
INTRODUCTION:
Tumor size has long been recognized as the strongest predictor of the outcome of patients with breast cancer. While screening programs are increasing the proportion of non-palpable breast cancer cases, it is important to know its relevance in the outcome. Our purpose was to evaluate various prognostic factors, including tumor palpability, in a multivariate fashion.
METHODS:
A Kaplan-Meier survival analysis was carried out for a retrospective cohort of 758 women with early stages of invasive breast carcinomas who were treated at the Breast Unit of the CECLINES (Caracas-Venezuela), Clinica el Viñedo y Centro Medico Dr. Rafael Guerra Mendez and University of Carabobo (Valencia-Venezuela), between 1987-2010. Endpoints were 10 years disease free survival (10 yrs-DFS) and 10 years overall survival (10 yrs-OS). Using a multivariate analysis, Hazard ratios (HR) were calculated in order to identify independent prognostic factors for 10 yrs-DFS and 10 yrs-OS.
RESULTS:
The median age for the entire cohort was 55yo; 293 (38.7%) tumors were not palpable and 465 (61.3%) were palpable; 42.2% (318 cases) were in pathological stage (PS) I and 57.8% (436 cases) in PS II. Tumor size was <1cm in 26% of cases; was between 1 - 3cm in 24.9% and >3cm in 49.1%; 23.2% had nodal involvement. In regard to immunohistochemistry markers, 633 were evaluable for estrogen receptor (ER); 599 for progesterone receptor (PR) and 578 for HER2. In regard to the status for these markers, 76.9% were ER+; 68.4% PR+ and 28.4% HER2+. Patients more likely to have non palpable tumors were ≥45yo (p = 0.001); smaller tumors (p<0.001); negative lymph nodes (p = 0.008); HER2 negative tumors (p = 0.001) and pathological stage I (p<0.001). The median of follow up was 42.6 months. The 10yrs-DFS was 78.7% and the 10yrs-OS was 91%. There were significant differences in 10yrs-DFS according to tumor palpability (non-palpable 81.1% vs palpable 73.3%, p = 0.002); tumor size (<1cm 81.7% vs 1-3cm 78.3% vs >3cm 77.3%, p = 0.017); nodal involvement (negative 81.9% vs positive 67.2%, p = 0.054); PS (I-IIA: 89.4% vs IIB, 74.9%, p<0.001); treatment with radiotherapy (yes 79% vs no 65.9%) and hormonotherapy (yes 78.9% vs no 70.1%). For 10yrs-OS, there were significant differences in palpability (palpable 78.2% vs non palpable 86.9%, p<0.001); tumor size (<1cm 96% vs 1-3cm 87.6% vs >3cm 75.3%, p = 0.027); HER2 (positive 95.9% vs negative 87.4%, p = 0.052); PS (I-IIA: 95.4% vs IIB, 86.5%, p<0.016) and radiotherapy (yes 92.7% vs no 79.1%, p = 0.001). In the multivariate analysis for 10 yrs-DFS, significant variables were: palpability (HR = 0.43 for non-palpable tumors, CI 95%: 0.242-0.781; p = 0.005) and radiotherapy (HR = 2.5 for patients that did not undergo radiotherapy, CI 95% 1.44 - 4.23). For 10 yrs-OS significant variables were HER2 (HR = 3.6 for HER2+, CI 95%: 1.18 - 10.86, p = 0.024). There was a statistical trend with palpability (HR = 0.23 for non-palpable tumors, CI 95%: 0.05-1.06; p = 0.06).
CONCLUSIONS
Women with early stage breast cancers with non-palpable tumors were less likely to present disease recurrence, independently of other factors. In the era of genomic profiling, a variable easily assessed in routine could be a surrogate factor for disease free survival.
Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-06-41.
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Evolution of filamentous bacteria during urban wastewater treatment by MBR. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2012; 47:863-872. [PMID: 22423993 DOI: 10.1080/10934529.2012.665001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Evolution of filamentous bacteria in two full-scale experimental MBR systems (microfiltration and ultrafiltration) was studied during two years. Sludge Retention Time (SRT) and Hydraulic Retention Time (HRT) were modified and acted as variables, together with temperature and variation in loading. With SRT values between 20 and 35 d and HRT between 31 and 40 h, both MBR systems presented a high density of filamentous bacteria, according to the Filamentous Index (FI) and Simplified Technique of Filamentous Count (STFC). Highest density was achieved when contaminant loads were high and temperature was low. However, the elevated presence of filamentous bacteria did not affect the quality of effluent or the permeability of the membranes. Nocardioform bacteria showed a high degree of adaptation to the characteristics of the system. Predominance of Nocardioforms gave rise to isolated episodes of massive growth at temperatures between 15 and 20°C, which in turn caused episodes of intense foaming whose most significant consequence was a loss in biomass, leading to a slight increase in transmembrane pressure. In the light of these results, FI and STFC should not be considered as suitable tools for predicting operational problems deriving from filamentous bacteria in MBR systems, which could be prevented through identification.
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Rf-GDOES analysis of composite metal/ceramic electroplated coatings with nano- to microceramic particles' size: issues in plasma sputtering of Ni/micro-SiC coatings. SURF INTERFACE ANAL 2011. [DOI: 10.1002/sia.3768] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Anodic titanium oxide as immobilized photocatalyst in UV or visible light devices. JOURNAL OF HAZARDOUS MATERIALS 2011; 186:2103-2109. [PMID: 21242031 DOI: 10.1016/j.jhazmat.2010.12.128] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 12/27/2010] [Indexed: 05/30/2023]
Abstract
Titanium anodizing can be a powerful technique to generate photoactive oxides, strongly adherent to the metallic substrate, and to modify their chemical composition by inducing doping effects. This work investigates the photocatalytic behavior of differently obtained anodic TiO(2) films under UV and visible light irradiation, so as to define the best treatment for wastewaters purifiers. Anodizing was performed in H(3)PO(4) and H(2)SO(4) mixtures or in fluoride containing electrolytes. Morphology, elemental composition and crystal structure of the anodic films were characterized by XDR, GDOES and SEM. When amorphous oxides were obtained, an annealing treatment was used to promote the formation of anatase crystals. Annealing was also performed in nitrogen atmosphere to induce nitrogen doping. The photocatalytic efficiency of anatase-enriched TiO(2) was investigated in rhodamine B photodegradation. Doping was induced not only by annealing but also directly by anodizing, and generated photoactivity in both the UV and Vis components of light.
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Characterization of cellular solids in Ti6Al4V for orthopaedic implant applications: Trabecular titanium. J Mech Behav Biomed Mater 2010; 3:373-81. [PMID: 20416551 DOI: 10.1016/j.jmbbm.2010.02.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Revised: 02/04/2010] [Accepted: 02/05/2010] [Indexed: 01/01/2023]
Abstract
EBM (Electron Beam Melting) technology can be used successfully to obtain cellular solids in metallic biomaterials that can greatly increase osseointegration in arthroprothesis and at the same time maintain good mechanical properties. The investigated structures, called Trabecular Titanium, usually cannot be obtained by traditional machining. Two samples: (A) with a smaller single cell area and, (B) with a bigger single cell area, were produced and studied in this project. They have been completely characterized and compared with the results in similar literature pertinent to Ti6Al4V EBM structures. Relative density was evaluated using different methods, the mean diameter of the open porosities was calculated by Scanning Electron Microscope images; the composition was evaluated using Energy-Dispersive X-Ray Spectroscopy; the microstructure (alpha-beta) was investigated using chemical etching and, the mechanical proprieties were investigated using UMTS. The mean porosity values resulted comparable with spongy bone (63% for A and 72% for B). The mean diameter of the single porosity (650 mum for A and 1400 mum for B) resulted compatible with the osseointegration data from the literature, in particular for sample A. The Vickers micro-hardness tests and the chemical etching demonstrated that the structure is fine, uniform and well distributed. The mechanical test proved that sample (A) was more resistant than sample (B), but sample (B) showed an elastic modulus almost equal to the value of spongy bone. The results of this study suggest that the two Ti6Al4V cellular solids can be used in biomedical applications to promote osseointegration demonstrating that they maybe successfully used in prosthetic implants. Additional implant results will be published in the near future.
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Liquid Resin Infusion process monitoring with embedded superimposed long period and short period Bragg grating sensor. EPJ WEB OF CONFERENCES 2010. [DOI: 10.1051/epjconf/20100634003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Chemical and electrochemical characterization of hybrid PVD+ALD hard coatings on tool steel. Electrochem commun 2009. [DOI: 10.1016/j.elecom.2009.08.052] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Activation of the TAS3-derived tasiRNA pathway in the root system of Arabidopsis thaliana. Comp Biochem Physiol A Mol Integr Physiol 2008. [DOI: 10.1016/j.cbpa.2008.04.546] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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BIOELECTRICAL IMPEDANCE ANALYSIS AND ORAL GLUCOSE TOLERANCE TEST. ATHEROSCLEROSIS SUPP 2008. [DOI: 10.1016/s1567-5688(08)70307-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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UNUSUAL CLINICAL PRESENTATION WITH TACHYCARDIA IN A PATIENT WITH LATENT AUTOINMUNE DIABETES ADULT. ATHEROSCLEROSIS SUPP 2008. [DOI: 10.1016/s1567-5688(08)70870-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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40
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TRYGLYCERIDES AND GLYCEMIC CONTROL HAVE INFLUCENCE ON SMALL ARTERY ELASTICITY IN DIABETIC PATIENTS. ATHEROSCLEROSIS SUPP 2008. [DOI: 10.1016/s1567-5688(08)70294-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Phosphate deficiency promotes modification of iron distribution in Arabidopsis plants. Biochimie 2006; 88:1767-71. [PMID: 16757083 DOI: 10.1016/j.biochi.2006.05.007] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2006] [Accepted: 05/05/2006] [Indexed: 11/19/2022]
Abstract
Phosphate (Pi) is an essential element for plant development and metabolism. Due to its low availability and mobility in soils, it is often a limiting nutrient for their growth. This phenomenon is reinforced by the formation of insoluble complexes in the environment with many cations, affecting the solubility of both phosphate and associated ions. This interaction is investigated here for iron, a strong phosphate chelator. Depleting the medium in phosphate clearly resulted in an increase of iron content in Arabidopsis. These modifications triggered molecular responses linked with iron status (transport, homeostasis and accumulation). Interestingly, physiological modifications affecting iron storage were also observed. The accumulation of phosphate/iron complexes in the vacuoles of plants grown in Pi-rich medium disappeared in Pi-depleted medium in favor of accumulation of iron inside the chloroplasts, likely associated with ferritin.
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Abstract
Pharmaceutical management of HIV infection is complex, and proper adherence to antiretroviral regimens is contingent on active patient involvement in treatment. We examined the relationship between patient understanding of HIV and its treatment and health literacy. Structured interviews were conducted with 157 HIV-infected individuals receiving care at a community-based clinic in Shreveport, Louisiana, USA. In all, 48% of patients were reading below a 9th grade level. One-third of patients could not name their HIV medications and this was significantly related to low literacy (P < 0.01). Two-thirds of those reading below the 9th grade level did not know how to take their medications correctly (P < 0.05), and 75% did not know the meaning of a CD4 count or viral load (P < 0.001). Patients with low literacy skills were more likely to state that their physician was their sole source of HIV information (P < 0.005). Physicians may require training to appropriately convey health information to patients of low literacy.
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Value of pro-BNP determinations in the follow-up of heart transplantation. J Heart Lung Transplant 2005. [DOI: 10.1016/j.healun.2004.11.251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Sonic band gaps in PCF preforms: enhancing the interaction of sound and light. OPTICS EXPRESS 2003; 11:2555-2560. [PMID: 19471368 DOI: 10.1364/oe.11.002555] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We study the localisation and control of high frequency sound in a dual-core square-lattice photonic crystal fibre preform. The coupled states of two neighboring acoustic resonances are probed using an interferometric set up, and experimental evidence is obtained for odd and even symmetry trapped states. Full numerical solutions of the acoustic wave equation show the existence of a two-dimensional sonic band gap, and numerical modelling of the strain field at the defects gives results that agree well with the experimental observations. The results suggest that sonic band gaps can be used to manipulate sound with great precision and enhance its interaction with light.
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Effect of Heat Treatment on Bovine Lactoperoxidase Activity in Skim Milk: Kinetic and Thermodynamic Analysis. J Food Sci 2003. [DOI: 10.1111/j.1365-2621.2003.tb14120.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Cortical silent period in two patients with meningioma and preoperative seizures: a pre- and postsurgical follow-up study. Clin Neurophysiol 2002; 113:597-603. [PMID: 11956005 DOI: 10.1016/s1388-2457(02)00021-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVES Prolongation of the cortical silent period (CSP) following transcranial magnetic stimulation has been reported in patients with partial epilepsy involving the primary motor cortex (M1). This study aimed to investigate the relationship between the expected intraindividual variations in risk factors for seizures and CSP duration. METHODS We studied a 59-year-old woman with a rolandic meningioma and simple motor partial seizures and a 71-year-old woman with a parietal/occipital meningioma and complex partial seizures. Both patients had seizure as their initial symptom with complete postsurgical remission. Repeated pre- and postoperative CSP recordings were made from both first dorsal interosseous muscles. We compared the results to those obtained in 13 normals. RESULTS In the patient with simple motor partial seizures, the CSP was significantly prolonged in preoperative recordings and 3 weeks after surgery. This CSP lengthening partly subsided 3 months after surgery. Finally, the CSP was normal 6, 8, and 18 months after surgery. In the patient with complex partial seizures, no CSP change was observed. CONCLUSIONS In our patient with a rolandic meningioma, CSP prolongation was observed when the risk of seizure relapse was supposed to be higher (preoperative and early postoperative periods). This supports the view that CSP changes reflect compensatory mechanisms in M1 epilepsy.
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Abstract
The plasma membrane guard cell slow anion channel is a key element at the basis of water loss control in plants allowing prolonged osmolite efflux necessary for stomatal closure. This channel has been extensively studied by electrophysiological approaches but its molecular identification is still lacking. Recently, we described that this channel was sharing some similarities with the mammalian ATP-binding cassette protein, cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel [Leonhardt, N. et al. (1999) Plant Cell 11, 1141-1151]. Here, using the patch-clamp technique and a bioassay, consisting in the observation of the change in guard cell protoplasts volume, we demonstrated that a functional antibody raised against the mammalian CFTR prevented ABA-induced guard cell protoplasts shrinking and partially inhibited the slow anion current. Moreover, this antibody immunoprecipitated a polypeptide from guard cell protein extracts and immunolabeled stomata in Vicia faba leaf sections. These results indicate that the guard cell slow anion channel is, or is closely controlled by a polypeptide, exhibiting one epitope shared with the mammalian CFTR.
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Reorganization of the motor cortex in a patient with congenital hemiparesis and mirror movements. Neurology 2000; 55:129-31. [PMID: 10891922 DOI: 10.1212/wnl.55.1.129] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abnormal branching of corticospinal fibers from the unaffected motor cortex is responsible for mirror movements in patients with congenital hemiparesis, but it is unknown which mechanisms enable these patients to lateralize motor activity. Using multiunit electromyographic analysis and transcranial magnetic stimulation, the authors provide evidence for nonbranched crossed and uncrossed corticospinal projections and intracortical inhibition of the mirror hand. They propose that this remarkable reorganization of the unaffected motor cortex helps these patients to reduce mirror movements.
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Engineering seed dormancy by the modification of zeaxanthin epoxidase gene expression. PLANT MOLECULAR BIOLOGY 1999; 39:1267-1274. [PMID: 10380812 DOI: 10.1023/a:100614502563] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Abscisic acid (ABA) is a plant hormone synthesized during seed development that is involved in the induction of seed dormancy. Delayed germination due to seed dormancy allows long-term seed survival in soil but is generally undesirable in crop species. Freshly harvested seeds of wild-type Nicotiana plumbaginifolia plants exhibit a clear primary dormancy that results in delayed germination, the degree of primary dormancy being influenced by environmental culture conditions of the mother plant. In contrast, seeds, obtained either from ABA-deficient mutant aba2-s1 plants directly or aba2-s1 plants grafted onto wild-type plant stocks, exhibited rapid germination under all conditions irrespective of the mother plant culture conditions. The ABA biosynthesis gene ABA2 of N. plumbaginifolia, encoding zeaxanthin epoxidase, was placed under the control of the constitutive 35S promoter. Transgenic plants overexpressing ABA2 mRNA exhibited delayed germination and increased ABA levels in mature seeds. Expression of an antisense ABA2 mRNA, however, resulted in rapid seed germination and in a reduction of ABA abundance in transgenic seeds. It appears possible, therefore, that seed dormancy can be controlled in this Nicotiana model species by the manipulation of ABA levels.
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MESH Headings
- Abscisic Acid/biosynthesis
- Abscisic Acid/genetics
- Gene Expression Regulation, Enzymologic
- Gene Expression Regulation, Plant
- Genes, Plant/genetics
- Genes, Plant/physiology
- Genetic Engineering
- Germination
- Homozygote
- Mutation
- Oxidoreductases/genetics
- Plant Leaves/genetics
- Plants, Genetically Modified
- Plants, Toxic
- Promoter Regions, Genetic/genetics
- RNA, Antisense/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Seeds/genetics
- Seeds/metabolism
- Seeds/physiology
- Temperature
- Time Factors
- Tobacco/genetics
- Tobacco/physiology
- Transgenes/genetics
- Transgenes/physiology
- Water/metabolism
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Engineering seed dormancy by the modification of zeaxanthin epoxidase gene expression. PLANT MOLECULAR BIOLOGY 1999; 39:1267-74. [PMID: 10380812 DOI: 10.1023/a:1006145025631] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Abscisic acid (ABA) is a plant hormone synthesized during seed development that is involved in the induction of seed dormancy. Delayed germination due to seed dormancy allows long-term seed survival in soil but is generally undesirable in crop species. Freshly harvested seeds of wild-type Nicotiana plumbaginifolia plants exhibit a clear primary dormancy that results in delayed germination, the degree of primary dormancy being influenced by environmental culture conditions of the mother plant. In contrast, seeds, obtained either from ABA-deficient mutant aba2-s1 plants directly or aba2-s1 plants grafted onto wild-type plant stocks, exhibited rapid germination under all conditions irrespective of the mother plant culture conditions. The ABA biosynthesis gene ABA2 of N. plumbaginifolia, encoding zeaxanthin epoxidase, was placed under the control of the constitutive 35S promoter. Transgenic plants overexpressing ABA2 mRNA exhibited delayed germination and increased ABA levels in mature seeds. Expression of an antisense ABA2 mRNA, however, resulted in rapid seed germination and in a reduction of ABA abundance in transgenic seeds. It appears possible, therefore, that seed dormancy can be controlled in this Nicotiana model species by the manipulation of ABA levels.
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MESH Headings
- Abscisic Acid/biosynthesis
- Abscisic Acid/genetics
- Gene Expression Regulation, Enzymologic
- Gene Expression Regulation, Plant
- Genes, Plant/genetics
- Genes, Plant/physiology
- Genetic Engineering
- Germination
- Homozygote
- Mutation
- Oxidoreductases/genetics
- Plant Leaves/genetics
- Plants, Genetically Modified
- Plants, Toxic
- Promoter Regions, Genetic/genetics
- RNA, Antisense/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Seeds/genetics
- Seeds/metabolism
- Seeds/physiology
- Temperature
- Time Factors
- Nicotiana/genetics
- Nicotiana/physiology
- Transgenes/genetics
- Transgenes/physiology
- Water/metabolism
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