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Humidity is a critical environmental factor in various applications, and its temperature dependence must be considered when developing thermo-hygrometer fiber sensors. The optical fibers that constitute the sensor must have a temperature reference, which should be resistant to humidity to avoid cross-sensitivities. This paper presents two innovative optical fibers insensitive to humidity over temperatures ranging from -20∘ C to 55°C. To the best of our knowledge, the novel standard size optical fibers coated with acrylate and silicone are tested under controlled conditions using an optical time-domain reflectometer sensor based on Rayleigh scattering. The sensor achieves meter-range resolution over kilometers of length with a response time of few minutes.
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BACKGROUND: Non-ischemic cerebral enhancing (NICE) lesions following aneurysm endovascular therapy are exceptionally rare, with unknown longitudinal evolution. OBJECTIVE: To evaluate the radiological behavior of individual NICE lesions over time. METHODS: Patients included in a retrospective national multicentric inception cohort were analyzed. NICE lesions were defined, using MRI, as delayed onset punctate, nodular, or annular foci enhancements with peri-lesion edema, distributed in the vascular territory of the aneurysm treatment, with no other confounding disease. Lesion burden and the longitudinal behavior of individual lesions were assessed. RESULTS: Twenty-two patients were included, with a median initial lesion burden of 36 (IQR 17-54) on the first MRI scan. Of the 22 patients with at least one follow-up MRI scan, 16 (73%) had new lesions occurring mainly within the first 200 weeks after the date of the procedure. The median number of new lesions per MRI was 6 (IQR 2-16). Among the same 22 patients, 7 (32%) had recurrent lesions. The median persistent enhancement of a NICE lesion was 13 weeks (IQR 6-30). No factor was predictive of early regression of enhancement activity with lesion regression kinetics mainly being patient-dependent. CONCLUSIONS: The behavior of individual NICE lesions was found to be highly variable with an overall patient-dependent regression velocity.
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BACKGROUND: The functional prognosis of severe traumatic brain injury (TBI) during the acute phase is often poor and uncertain. We aimed to quantify the elements that shade the degree of uncertainty in prognostic determination of TBI and to better understand the role of clinical experience in prognostic quality. METHODS: This was an observational, prospective, multicenter study. The medical records of 16 patients with moderate or severe TBI in 2020 were randomly drawn from a previous study and submitted to two groups of physicians: senior and junior. The senior physician group had graduated from a critical care fellowship, and the junior physician group had at least 3 years of anesthesia and critical care residency. They were asked for each patient, based on the reading of clinical data and CT images of the first 24 h, to determine the probability of an unfavorable outcome (Glasgow Outcome Scale < 4) at 6 months between 0 and 100, and their level of confidence. These estimations were compared with the actual evolution. RESULTS: Eighteen senior physicians and 18 junior physicians in 4 neuro-intensive care units were included in 2021. We observed that senior physicians performed better than junior physicians, with 73% (95% confidence interval (CI) 65-79) and 62% (95% CI 56-67) correct predictions, respectively, in the senior and junior groups (p = 0.006). The risk factors for incorrect prediction were junior group (OR 1.71, 95% CI 1.15-2.55), low confidence in the estimation (OR 1.76, 95% CI 1.18-2.63), and low level of agreement on prediction between senior physicians (OR 6.78, 95% CI 3.45-13.35). CONCLUSIONS: Determining functional prognosis in the acute phase of severe TBI involves uncertainty. This uncertainty should be modulated by the experience and confidence of the physician, and especially on the degree of agreement between physicians.
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Lesiones Traumáticas del Encéfalo , Médicos , Humanos , Estudios Prospectivos , Lesiones Traumáticas del Encéfalo/diagnóstico por imagen , Lesiones Traumáticas del Encéfalo/terapia , Pronóstico , Factores de RiesgoRESUMEN
OBJECTIVE: To develop a multidisciplinary French reference that addresses initial pre- and in-hospital management of a mild traumatic brain injury patient. DESIGN: A panel of 22 experts was formed on request from the French Society of Emergency Medicine (SFMU) and the French Society of Anaesthesiology and Critical Care Medicine (SFAR). A policy of declaration and monitoring of links of interest was applied and respected throughout the process of producing the guidelines. Similarly, no funding was received from any company marketing a health product (drug or medical device). The expert panel had to respect and follow the Grade® (Grading of Recommendations Assessment, Development and Evaluation) methodology to evaluate the quality of the evidence on which the recommendations were based. Given the impossibility of obtaining a high level of evidence for most of the recommendations, it was decided to adopt a "Recommendations for Professional Practice" (RPP) format, rather than a Formalized Expert Recommendation (FER) format, and to formulate the recommendations using the terminology of the SFMU and SFAR Guidelines. METHODS: Three fields were defined: 1) pre-hospital assessment, 2) emergency room management, and 3) emergency room discharge modalities. The group assessed 11 questions related to mild traumatic brain injury. Each question was formulated using a PICO (Patients Intervention Comparison Outcome) format. RESULTS: The experts' synthesis work and the application of the GRADE® method resulted in the formulation of 14 recommendations. After two rounds of rating, strong agreement was obtained for all recommendations. For one question, no recommendation could be made. CONCLUSION: There was strong agreement among the experts on important, transdisciplinary recommendations, the purpose of which is to improve management practices for patients with mild head injury.
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Anestesiología , Conmoción Encefálica , Humanos , Cuidados Críticos , Servicio de Urgencia en Hospital , HospitalesRESUMEN
BACKGROUND: Predicting functional outcome in critically ill patients with traumatic brain injury (TBI) strongly influences end-of-life decisions and information for surrogate decision makers. Despite well-validated prognostic models, clinicians most often rely on their subjective perception of prognosis. In this study, we aimed to compare physicians' predictions with the International Mission on Prognosis and Analysis of Clinical Trials in TBI (IMPACT) prognostic model for predicting an unfavorable functional outcome at 6 months after moderate or severe TBI. METHODS: PREDICT-TBI is a prospective study of patients with moderate to severe TBI. Patients were admitted to a neurocritical care unit and were excluded if they died or had withdrawal of life-sustaining treatments within the first 24 h. In a paired study design, we compared the accuracy of physician prediction on day 1 with the prediction of the IMPACT model as two diagnostic tests in predicting unfavorable outcome 6 months after TBI. Unfavorable outcome was assessed by the Glasgow Outcome Scale from 1 to 3 by using a structured telephone interview. The primary end point was the difference between the discrimination ability of the physician and the IMPACT model assessed by the area under the curve. RESULTS: Of the 93 patients with inclusion and exclusion criteria, 80 patients reached the primary end point. At 6 months, 29 patients (36%) had unfavorable outcome. A total of 31 clinicians participated in the study. Physicians' predictions showed an area under the curve of 0.79 (95% confidence interval 0.68-0.89), against 0.80 (95% confidence interval 0.69-0.91) for the laboratory IMPACT model, with no statistical difference (p = 0.88). Both approaches were well calibrated. Agreement between physicians was moderate (κ = 0.56). Lack of experience was not associated with prediction accuracy (p = 0.58). CONCLUSIONS: Predictions made by physicians for functional outcome were overall moderately accurate, and no statistical difference was found with the IMPACT models, possibly due to a lack of power. The significant variability between physician assessments suggests prediction could be improved through peer reviewing, with the support of the IMPACT models, to provide a realistic expectation of outcome to families and guide discussions about end-of-life decisions.
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Lesiones Traumáticas del Encéfalo , Humanos , Estudios Prospectivos , Lesiones Traumáticas del Encéfalo/diagnóstico , Lesiones Traumáticas del Encéfalo/terapia , Pronóstico , Escala de Consecuencias de Glasgow , MuerteRESUMEN
Recent developments in embedded electronics require the development of micro sources of energy. In this paper, the fabrication of an on-chip interdigitated all-solid-state supercapacitor, using porous gold electrodes and a PVA/KOH quasisolid electrolyte, is demonstrated. The fabrication of the interdigitated porous gold electrode is performed using an original bottom-up approach. A templating method is used for porosity, using a wet chemistry process followed by microfabrication techniques. This paper reports the first example of an all-gold electrode micro-supercapacitor. The supercapacitor exhibits a specific capacitance equal to 0.28 mF·cm-2 and a specific energy of 0.14 mJ·cm-2. The capacitance value remains stable up to more than 8000 cycles.
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Electrólitos , Electrónica , Porosidad , Electrodos , Capacidad EléctricaRESUMEN
Optical Frequency Domain Reflectometry (OFDR) is used to make temperature distributed sensing measurements along a fiber by exploiting Rayleigh backscattering. This technique presents high spatial and high temperature resolutions on temperature ranges of several hundred of degrees Celsius. With standard telecommunications fibers, measurement errors coming from the correlation between a high temperature Rayleigh trace and the one taken as a reference at room temperature could be present at extremely high temperatures. These correlation errors, due to low backscattering signal amplitude and unstable backscattering signal, induce temperature measurement errors. Thus, for high temperature measurement ranges and at extremely high temperatures (e.g., at 800 °C), a known solution is to use fibers with femtosecond laser inscribed nanograting. These fs-laser-insolated fibers have a high amplitude and thermally stable scattering signal, and they exhibit lower correlation errors. In this article, temperature sensing at 800 °C is reported by using an annealed zirconia-doped optical fiber with an initial 40.5-dB enhanced scattering signal. The zirconia-doped fiber presents initially OFDR losses of 2.8 dB/m and low OFDR signal drift at 800 °C. The ZrO2-doped fiber is an alternative to nanograting-inscribed fiber to make OFDR distributed fiber sensing on several meters with gauge lengths of 1 cm at high temperatures.
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BACKGROUND AND PURPOSE: Cangrelor is a P2Y12 inhibitor that presents the advantage of having a short half-life. Its use may be helpful in the management of antiplatelet therapy for patients with intracranial aneurysms treated by stent-assisted coiling or flow-diverter stents. The purpose of this study was to report early experiences in using cangrelor for such indications. MATERIAL AND METHODS: From October 2017 to November 2018, 7 consecutive patients (5 females, 2 males, mean ageâ¯= 56 years) were managed with cangrelor as antiplatelet therapy, combined with aspirin, for stent-assisted coiling embolization and flow-diverter embolization of challenging intracranial aneurysms. Anti-aggregation protocols, including cangrelor, were systematically recorded. Treatment-related complications (minor/major hemorrhagic complications, ischemic complications) as well as clinical and angiographic outcomes (evaluated at 8.7⯱ 4.2 and 8.75⯱ 10 months, respectively) were retrospectively analyzed. RESULTS: Of the aneurysms 71.4% (5 out of 7) were ruptured and treated in the acute phase. In one case cangrelor was used as an alternative to clopidogrel in an asymptomatic hemorrhagic complication after stent-assisted coiling for better control of a possible worsening of the intracranial bleeding. Of the patients, 1 (14%) with a complex ruptured MCA aneurysm treated with a flow-diverter stent experienced a severe intracranial hemorrhage, which occurred after switching the cangrelor to ticagrelor and eventually led to death. No hemorrhagic complications under cangrelor were recorded for the six remaining patients. No mRS worsening was observed at discharge, except for the patient who died and six out of the seven patients had a mRS ≤2 at follow-up. CONCLUSION: Cangrelor is a new antiplatelet therapy with a P2Y12 inhibiting effect, with a rapid onset and offset of action, owing to its short half-life. This cases series presents a pilot experience with promising results in terms of antiplatelet management for challenging intracranial aneurysms treated by stent assisted coiling or flow-diverter stents.
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Adenosina Monofosfato/análogos & derivados , Aneurisma Roto/terapia , Embolización Terapéutica/métodos , Aneurisma Intracraneal/terapia , Antagonistas del Receptor Purinérgico P2Y/uso terapéutico , Adenosina Monofosfato/uso terapéutico , Aneurisma Roto/diagnóstico por imagen , Aspirina/uso terapéutico , Angiografía Cerebral , Femenino , Humanos , Aneurisma Intracraneal/diagnóstico por imagen , Masculino , Persona de Mediana Edad , StentsRESUMEN
OBJECTIVE: We intended to analyze the outcomes and predictive factors for underestimating the prostate cancer (PCa) grade group (GG) from prostate biopsies in a large monocentric cohort of patients treated by minimally invasive radical prostatectomy (RP). MATERIALS AND METHODS: Using a monocentric prospectively maintained database, we included 3062 patients who underwent minimally invasive RP between 2006 and 2013. We explored clinicopathologic features and outcomes associated with a GG upgrade from biopsy to RP. Multivariate logistic regression was used to develop and validate a nomogram to predict upgrading for GG1. RESULTS: Biopsy GG was upgraded after RP in 51.5% of cases. Patients upgraded from GG1 to GG2 or GG3 after RP had a longer time to biochemical recurrence than those with GG2 or GG3 respectively, on both biopsy and RP, but a shorter time to biochemical recurrence than those who remained GG1 after RP (P < .0001). In multivariate analyses, variables predicting upgrading for GG1 PCa were age (P = .0014), abnormal digital rectal examination (P < .0001), prostate-specific antigen density (P < .0001), percentage of positive cores (P < .0001), and body mass index (P = .037). A nomogram was generated and validated internally. CONCLUSIONS: Biopsy grading system is misleading in approximately 50% of cases. Upgrading GG from biopsy to RP may have consequences on clinical outcomes. A nomogram using clinicopathologic features could aid the probability of needing to upgrade GG1 patients at their initial evaluation.
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Nomogramas , Neoplasias de la Próstata/patología , Neoplasias de la Próstata/cirugía , Anciano , Tacto Rectal , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Procedimientos Quirúrgicos Mínimamente Invasivos , Clasificación del Tumor , Vigilancia de la Población , Estudios Prospectivos , Antígeno Prostático Específico/metabolismo , Prostatectomía , Neoplasias de la Próstata/metabolismo , Factores de RiesgoRESUMEN
BACKGROUND: Cascade carrier testing within cystic fibrosis (CF) affected families offers relatives of CF patients the opportunity to know their status regarding the mutation that segregates within their family, and thus to make informed reproductive choices. As an Australian study has recently shown that this test seemed underused, we searched to assess uptake of this test in a European area where CF is common, and to report its public health implications. METHODS: This study relied on 40 CF-affected families from western Brittany, France. Investigations included drawing of family trees and registration of carrier tests performed in those families. RESULTS: Of the 459 relatives eligible for testing, 185 were tested, leading to an adjusted uptake rate of testing of 40.7% (95% CI: [34.1%; 47.3%]). The main predictors for having testing were being female (p=0.031) and having a high prior risk (p<0.001). Planning a pregnancy or expecting a child (reported in at least 38.4% of tested relatives) also appeared critical in choosing to be tested. Overall, carrier testing allowed to reassure more than 1/4 of the relatives and to detect five new 1-in-4 at-risk couples who then requested prenatal diagnosis. CONCLUSIONS: This observational study assesses, for first time in Europe, uptake of CF cascade carrier testing within CF families, which is a critical tool to reassure non-carriers and to detect early new at-risk couples.
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Fibrosis Quística , Asesoramiento Genético/psicología , Adulto , Conducta de Elección , Fibrosis Quística/diagnóstico , Fibrosis Quística/epidemiología , Fibrosis Quística/genética , Fibrosis Quística/psicología , Salud de la Familia , Femenino , Francia/epidemiología , Tamización de Portadores Genéticos/métodos , Tamización de Portadores Genéticos/estadística & datos numéricos , Humanos , Masculino , Embarazo , Diagnóstico Prenatal/métodos , Diagnóstico Prenatal/psicología , Diagnóstico Prenatal/estadística & datos numéricos , Salud Reproductiva , Medición de Riesgo/métodosRESUMEN
Sarcoidosis is a multisystemic inflammatory disease of unknown etiology, characterized by noncaseous epithelioid cell granulomas. The evolution of the disease may be complicated by opportunistic infections such as aspergillosis, that usually appears in type IV sarcoidosis. We present the case of a 74 year-old women with a history of sarcoidosis for over 7 years, who presented for hemoptysis. She was diagnosed with pulmonary cavitary aspergillosis and treatment with ltraconazole was initiated. The patient was monitored every two months. At the one year follow up, the patient was asymptomatic, with a good treatment tolerance and no decline in lung function, despite the pulmonary fibrosis. The sputum exams continued to be positive for Aspergillus, the HRCT-scan described a chronic pulmonary aspergillosis. The antifungical treatment was continued, under careful monitoring. The patient remained asymptomatic with no further decline in lung volumes. The particularity of the case consists in the lack of symptoms, despite pulmonary fibrosis, and the therapeutic challenges of chronic pulmonary aspergillosis.
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Aspergillus/aislamiento & purificación , Huésped Inmunocomprometido , Infecciones Oportunistas/complicaciones , Aspergilosis Pulmonar/complicaciones , Sarcoidosis/complicaciones , Anciano , Antifúngicos/uso terapéutico , Femenino , Hemoptisis/microbiología , Humanos , Itraconazol/uso terapéutico , Infecciones Oportunistas/tratamiento farmacológico , Aspergilosis Pulmonar/tratamiento farmacológico , Esputo/microbiología , Resultado del TratamientoRESUMEN
BACKGROUND: Acute kidney injury (AKI) in the setting of hemophagocytic lymphohistiocytosis (HLH) is poorly characterized. This study aims to describe the incidence, clinical and biological features, and outcome associated with AKI in this population. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: Patients with secondary HLH admitted to a single center from February 2007 through January 2013. 95 patients were included in the study. PREDICTOR: AKI. OUTCOMES: Recovery of kidney function, 6-month mortality, and complete remission of the underlying disease. MEASUREMENTS: AKI was defined according to the KDIGO 2012 guideline. Recovery of kidney function was defined as improvement in serum creatinine level, with return to baseline serum creatinine level ±26.5µmol/L. RESULTS: HLH was related to hematologic malignancy in 73 (77%), infectious disease in 21 (22%), and autoimmune disease in 9 (10%) patients and was multifactorial in 10 (11%) patients. The cause was undetermined in 2 (2%) patients. The incidence of AKI during HLH is high (62%), and 59% of the AKI population required renal replacement therapy. Main causes of AKI were acute tubular necrosis (49%), hypoperfusion (46%), tumor lysis syndrome (29%), or HLH-associated glomerulopathies (17%). At 6 months, 32% of the patients with AKI had chronic kidney disease. Two factors were associated independently with 6-month mortality by multivariable analysis: AKI stage ≥ 2 (OR, 2.61; 95% CI, 1.08-6.29; P=0.03) and an underlying hematologic malignancy (OR, 3.1; 95% CI, 1.05-9.14; P=0.04). In patients with hematologic malignancy, AKI was associated with lower 6-month complete remission (non-AKI, 25%; AKI patients, 5%; P=0.05). LIMITATIONS: Retrospective study, lack of histologic data. CONCLUSIONS: AKI in patients with HLH is frequent and adversely affects remission and survival. Early intensive management, including administration of etoposide, nephrotoxic drug withdrawal, prevention of tumor lysis syndrome, or aggressive supportive care, might improve kidney function and survival.
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Lesión Renal Aguda/etiología , Neoplasias Hematológicas/complicaciones , Linfohistiocitosis Hemofagocítica/complicaciones , Terapia de Reemplazo Renal , Síndrome de Lisis Tumoral/complicaciones , Lesión Renal Aguda/mortalidad , Lesión Renal Aguda/terapia , Adulto , Estudios de Cohortes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Recuperación de la Función , Estudios Retrospectivos , Índice de Severidad de la EnfermedadRESUMEN
OBJECTIVE: To report the long-term outcome of neurologic involvement in patients with Behçet's disease (BD). METHODS: We performed a retrospective analysis of 115 patients who fulfilled the international criteria for BD (57% male; median age 37 years [interquartile range (IQR) 30-46 years]) and had neuro-BD (NBD) after exclusion of cerebral venous thrombosis. Factors associated with relapse of NBD, inability to perform activities of daily living, and mortality were assessed. RESULTS: Seventy-eight patients (68%) presented with acute NBD and 37 (32%) presented with a progressive course. The HLA-B51 allele was carried by 49% of the patients. Overall, 46 of 115 patients (40%) had severe disability at baseline, represented by a Rankin score of ≥3. The 5- and 7-year event-free survival rates were 65% and 53%, respectively. In multivariate analysis, a positive HLA-B51 status was independently associated with the risk of NBD relapse, with an odds ratio (OR) of 3.6 (95% confidence interval [95% CI] 1.5-9.1). After a median followup of 73 months (IQR 59-102 months), 29 patients (25.2%) became dependent (were unable to perform activities of daily living) or died. Factors independently associated with poor outcome were paresis at onset (OR 6.47 [95% CI 1.73-24.23]) and location of inflammatory lesions at the brainstem on magnetic resonance imaging (OR 8.41 [1.03-68.43]). All 115 patients were treated with corticosteroids; 53 (46.1%) also took cyclophosphamide and 40 (34.8%) also took azathioprine. A trend toward longer event-free survival was observed in patients with severe NBD (i.e., with a Rankin score of ≥3 at onset) receiving intravenous cyclophosphamide compared with those receiving azathioprine (P = 0.06). CONCLUSION: Our findings indicate that NBD is a severe condition in which patients with the HLA-B51 allele appear to experience a worse prognosis.
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Síndrome de Behçet/diagnóstico , Síndrome de Behçet/genética , Enfermedades del Sistema Nervioso/diagnóstico , Enfermedades del Sistema Nervioso/genética , Adulto , Alelos , Síndrome de Behçet/epidemiología , Comorbilidad , Femenino , Antígeno HLA-B51/genética , Humanos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Enfermedades del Sistema Nervioso/epidemiología , Pronóstico , Estudios Retrospectivos , Tasa de SupervivenciaRESUMEN
BACKGROUND: Little information is available on the titration of morphine postoperatively in children. This observational study describes the technique in terms of the bolus dose, the number of boluses required, the time to establish analgesia, and side effects noted. METHODS: Morphine was administered if pain score (VAS or FLACC) was >30. Patients weighing less than 45 kg received a 50 µg·kg(-1) bolus of morphine with subsequent boluses of 25 µg kg(-1) as required. Patients weighing over 45 kg received boluses of 2 mg. Pain and Ramsay scores were recorded up to 90 min after the end of the titration and any side effect or complication was noted. Data are presented as the median [interquartile Q1-Q3 range]. RESULTS: Overall, 103 children were studied. The median age was 4.2 years [0.8-12.2 years]. The median weight was 15.5 kg [8.2-35.0 kg]. The protocol was effective for pain control with a significant decrease in pain scores over time. The median pain score (VAS or FLACC) was 70 [50-80] prior to the initial bolus and 0 [0-10] 90 min after the last bolus. Median Ramsay score was 1 [1-2] before the initial bolus administration and 4 [2-4] at 90 min. The median total dose of morphine was 100 [70-140] µg·kg(-1) , and the median number of boluses was 3 [2-5]. Side effects were observed in 17% of cases. No serious complications were observed. CONCLUSIONS: Our study of morphine titration for children shows that our protocol was effective for pain control with a significant decrease in pain scores over time. No serious complications were encountered. More studies on larger cohorts of patients are needed to confirm the efficacy and safety of this protocol.
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Analgésicos Opioides/administración & dosificación , Analgésicos Opioides/uso terapéutico , Morfina/administración & dosificación , Morfina/uso terapéutico , Adolescente , Analgésicos Opioides/efectos adversos , Niño , Preescolar , Femenino , Humanos , Lactante , Inyecciones Intravenosas , Masculino , Morfina/efectos adversos , Dimensión del Dolor/efectos de los fármacos , Dolor Postoperatorio/tratamiento farmacológico , Náusea y Vómito Posoperatorios/prevención & control , Sala de RecuperaciónRESUMEN
Ionic copper- or silver-doped dense silica rods have been prepared by sintering sol-gel porous silica xerogels doped with ionic precursors. The precipitation of Cu or Ag nanoparticles was achieved by heat treatment under hydrogen followed by annealing under air atmosphere. The surface plasmon resonance bands of copper and silver nanoparticles have been clearly observed in the absorption spectra. The spectral positions of these bands were found to depend slightly on the particle size, which could be tuned by varying the annealing conditions. Hence, transmission electron microscopy showed the formation of spherical copper nanoparticles with diameters in the range of 3.3 to 5.6 nm. On the other hand, in the case of silver, both spherical nanoparticles with diameters in the range of 3 to 6 nm and nano-rods were obtained.
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Pulsed femtosecond laser irradiation at low repetition rate, without any annealing, has been used to localize the growth of PbS nanoparticles, for the first time, inside a transparent porous silica matrix prepared by a sol-gel route. Before the irradiation, the porous silica host has been soaked within a solution containing PbS precursors. The effect of the incident laser power on the particle size was studied. X-ray diffraction was used to identify the PbS crystallites inside the irradiated areas and to estimate the average particle size. The localized laser irradiation led to PbS crystallite size ranging between 4 and 8 nm, depending on the incident femtosecond laser power. The optical properties of the obtained PbS-silica nanocomposites have been investigated using absorption and photoluminescence spectroscopies. Finally, the stability of PbS nanoparticles embedded inside the host matrices has been followed as a function of time, and it has been shown that this stability depends on the nanoparticle mean size.
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Hybrid organic-inorganic bis-tetrabutylammonium-7,7'-(iminundecahydro-closo-dodecaborate)-9,9'-(dihexyl)-2,2'-bifluorene (5) was prepared, and the influence of the closo-dodecaborate cluster on the two-photon absorption properties of bi-fluorene derivatives was demonstrated.
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Single- and multibranched centrosymmetric derivatives incorporating B12 clusters [B12H11-N(H)=C(H)-C6H4-C6H4-C(H)=(H)N-B12H11]2- (3) and [1,3,5-(4-(B12H11-N(H)=C(H))-C6H4)-C6H3]3- (5) have been synthesized. Both derivatives were characterized by multinuclear NMR and ESI-MS analyses. To the best of our knowledge, compound 5 is the first example of a multicage derivative bearing three B12 units. Compounds 3 and 5 are only slightly yellowish colored. The UV-vis absorption curves of 3 and 5 show intense absorption bands at 360 and 314 nm, respectively. This result permits us to confirm the strong donor effect of the B12 cluster. The hypsochrome effect observed for compound 5 compared to that of compound 3 confirms the interest in multibranched derivatives for the preparation of two-photon absorption materials active in the visible range.