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1.
Am J Public Health ; 113(1): 79-88, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36356280

RESUMEN

Objectives. To compare 4 COVID-19 surveillance metrics in a major metropolitan area. Methods. We analyzed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in wastewater influent and primary solids in Raleigh, North Carolina, from April 10 through December 13, 2020. We compared wastewater results with lab-confirmed COVID-19 cases and syndromic COVID-like illness (CLI) cases to answer 3 questions: (1) Did they correlate? (2) What was the temporal alignment of the different surveillance systems? (3) Did periods of significant change (i.e., trends) align? Results. In the Raleigh sewershed, wastewater influent, wastewater primary solids, lab-confirmed cases, and CLI were strongly or moderately correlated. Trends in lab-confirmed cases and wastewater influent were observed earlier, followed by CLI and, lastly, wastewater primary solids. All 4 metrics showed sustained increases in COVID-19 in June, July, and November 2020 and sustained decreases in August and September 2020. Conclusions. In a major metropolitan area in 2020, the timing of and trends in municipal wastewater, lab-confirmed case, and syndromic case surveillance of COVID-19 were in general agreement. Public Health Implications. Our results provide evidence for investment in SARS-CoV-2 wastewater and CLI surveillance to complement information provided through lab-confirmed cases. (Am J Public Health. 2023;113(1):79-88. https://doi.org/10.2105/AJPH.2022.307108).


Asunto(s)
COVID-19 , Humanos , COVID-19/epidemiología , SARS-CoV-2 , Aguas Residuales , North Carolina/epidemiología , Vigilancia de Guardia , ARN Viral
2.
Inorg Chem ; 61(9): 3997-4008, 2022 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-35020371

RESUMEN

In this study, aluminum complexes bearing ferrocene-based and arylthiomethylphenolate ligands were synthesized, and their catalytic activity for ε-caprolactone (CL) polymerization was investigated. The catalytic activity of the reduced form of Al complexes was higher than that of the oxidized form. The CL polymerization rate of the reduced form fcO2AlMe (75 min, conversion = 100%) was higher than that of the oxidized form fcoxO2AlMe (4320 min, conversion = 45%), and the CL polymerization rate of fc(OAlMe2)2 (40 min, conversion = 100%) was higher than that of fcox(OAlMe2)2 (60 min, conversion = 97%). Electron deficiency substituents on phenolate decreased the catalytic activity of Al complexes bearing arylthiomethylphenolate ligands. Density functional theory calculations revealed that thioether coordination stabilized the transition state (TS1) and that the oxidized form fcox(OAlMe2)2 exhibited weaker thioether coordination and higher activation energy in TS1 compared with those of the reduced form fcO2AlMe. In addition, our study determined that the thioether group is a suitable chelating group for Al catalysts in CL polymerization due to its labile nature.

3.
BMC Cancer ; 21(1): 1225, 2021 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-34781919

RESUMEN

BACKGROUND: Limited treatment options exist for relapsed advanced lung squamous cell carcinoma (SCC), leading to poor outcomes compared with adenocarcinoma. This study aimed to investigate the efficacy of second-line afatinib versus chemotherapy in patients with advanced lung SCC who progressed after first-line chemotherapy. METHODS: In this retrospective, multisite cohort study, we recruited patients with initial locally advanced or metastatic lung SCC from four institutes in Taiwan between June 2014 and October 2020. The primary endpoint of this study was progression-free survival (PFS), and the secondary endpoints were the objective response rate (ORR), disease control rate (DCR), and overall survival (OS). RESULTS: The present study enrolled 108 patients: 19 received second-line afatinib, and 89 received second-line chemotherapy. The median ages were 71 and 67 years, respectively. PFS was significantly longer among patients who received afatinib than among those who received chemotherapy (median 4.7 months [95% confidence interval (CI), 0.1-7.5] vs. 2.6 months [95% CI, 0.9-6.7]; hazard ratio (HR) 0.53 [95% CI 0.32-0.88], p = 0.013). Compared with the chemotherapy group, OS was longer in the afatinib group but did not reach significance (median 16.0 months [95% CI, 6.1-22.0] vs. 12.3 months [6.2-33.9]; HR 0.65 [95% CI 0.38-1.11], p = 0.112). CONCLUSIONS: Afatinib offered a longer PFS and comparable OS to chemotherapy in advanced lung SCC patients in a real-world setting, it may be considered as a 2nd line alternative treatment choice for immunotherapy unfit advanced lung SCC patients.


Asunto(s)
Afatinib/uso terapéutico , Antineoplásicos/uso terapéutico , Carcinoma de Células Escamosas/tratamiento farmacológico , Neoplasias Pulmonares/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/uso terapéutico , Anciano , Anciano de 80 o más Años , Carcinoma de Células Escamosas/mortalidad , Carcinoma de Células Escamosas/patología , Femenino , Humanos , Neoplasias Pulmonares/mortalidad , Neoplasias Pulmonares/patología , Masculino , Persona de Mediana Edad , Supervivencia sin Progresión , Estudios Retrospectivos , Taiwán
4.
Inorg Chem ; 60(14): 10535-10549, 2021 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-34232620

RESUMEN

Trinuclear aluminum complexes bearing bipyrazoles were synthesized, and their catalytic activity for ε-caprolactone (CL) polymerization was investigated. DBu2Al3Me5 exhibited higher catalytic activity than did the dinuclear aluminum complex LBu2Al2Me4 (16 times as high for CL polymerization; [CL]:[DBu2Al3Me5]:[BnOH] = 100:0.5:5, [DBu2Al3Me5] = 10 mM, conversion 93% after 18 min at room temperature). Density functional theory calculations revealed a polymerization mechanism in which CL first approached the central Al atom and then moved to an external Al. The coordinated CL ring was opened because the repulsion of two tert-butyl groups on the ligands pushed an alkoxide initiator on an external Al to initiate CL. In these trinuclear Al catalysts, the central Al plays a role in monomer capture and then collaborates with the external Al to activate CL, accelerating polymerization.

5.
BMC Gastroenterol ; 21(1): 228, 2021 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-34016057

RESUMEN

BACKGROUND: Many factors cause hospital mortality (HM) after liver transplantation (LT). METHODS: We performed a retrospective research in a single center from October 2005 to June 2019. The study included 463 living donor LT patients. They were divided into a no-HM group (n = 433, 93.52%) and an HM group (n = 30, 6.48%). We used logistic regression analysis to determine how clinical features and surgical volume affected HM. We regrouped patients based on periods of surgical volume and analyzed the clinical features. RESULTS: Multivariate analysis revealed that donor age (OR = 1.050, 95% CI 1.011-1.091, p = 0.012), blood loss (OR = 1.000, 95% CI 1.000-1.000, p = 0.004), and annual surgical volumes being < 30 LTs (OR = 2.540, 95% CI 1.011-6.381, p = 0.047) were significant risk factors. A comparison of years based on surgical volume found that when the annual surgical volumes were at least 30 the recipient age (p = 0.023), donor age (p = 0.026), and ABO-incompatible operations (p < 0.001) were significantly higher and blood loss (p < 0.001), operative time (p < 0.001), intensive care unit days (p < 0.001), length of stay (p = 0.011), rate of re-operation (p < 0.001), and HM (p = 0.030) were significantly lower compared to when the annual surgical volumes were less than 30. CONCLUSIONS: Donor age, blood loss and an annual surgical volume < 30 LTs were significant pre- and peri-operative risk factors. Hospital mortality and annual surgical volume were associated with statistically significant differences; surgical volume may impact quality of care and transplant outcomes.


Asunto(s)
Trasplante de Hígado , Mortalidad Hospitalaria , Humanos , Donadores Vivos , Estudios Retrospectivos , Factores de Riesgo
6.
Sensors (Basel) ; 21(14)2021 Jul 12.
Artículo en Inglés | MEDLINE | ID: mdl-34300501

RESUMEN

Ubiquitous health management (UHM) is vital in the aging society. The UHM services with artificial intelligence of things (AIoT) can assist home-isolated healthcare in tracking rehabilitation exercises for clinical diagnosis. This study combined a personalized rehabilitation recognition (PRR) system with the AIoT for the UHM of lower-limb rehabilitation exercises. The three-tier infrastructure integrated the recognition pattern bank with the sensor, network, and application layers. The wearable sensor collected and uploaded the rehab data to the network layer for AI-based modeling, including the data preprocessing, featuring, machine learning (ML), and evaluation, to build the recognition pattern. We employed the SVM and ANFIS methods in the ML process to evaluate 63 features in the time and frequency domains for multiclass recognition. The Hilbert-Huang transform (HHT) process was applied to derive the frequency-domain features. As a result, the patterns combining the time- and frequency-domain features, such as relative motion angles in y- and z-axis, and the HHT-based frequency and energy, could achieve successful recognition. Finally, the suggestive patterns stored in the AIoT-PRR system enabled the ML models for intelligent computation. The PRR system can incorporate the proposed modeling with the UHM service to track the rehabilitation program in the future.


Asunto(s)
Inteligencia Artificial , Terapia por Ejercicio , Ejercicio Físico , Humanos , Aprendizaje Automático , Movimiento (Física)
7.
Environ Sci Technol ; 53(19): 11560-11568, 2019 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-31448917

RESUMEN

We developed a new dynamic model to characterize how light and nitrogen regulate the cellular processes of photosynthetic microalgae leading to transient changes in the production of neutral lipids, carbohydrates, and biomass. Our model recapitulated the versatile neutral lipid synthesis pathways via (i) carbon reuse from carbohydrate metabolism under nitrogen sufficiency and (ii) fixed carbon redirection under nitrogen depletion. We also characterized the effects of light adaptation, light inhibition hysteresis, and nitrogen limitation on photosynthetic carbon fixation. The formulated model was calibrated and validated with experimental data of Dunaliella viridis cultivated in a lab-scale photobioreactor (PBR) under various light (low/moderate/high) and nitrogen (sufficient/limited) conditions. We conducted the identifiability, uncertainty, and sensitivity analyses to verify the model reliability using the profile likelihood method, the Markov chain Monte Carlo (MCMC) technique, and the extended Fourier Amplitude Sensitivity Test (eFAST). Our model predictions agreed well with experimental observations and suggested potential model improvement by incorporating a lipid degradation mechanism. The insights from our model-driven analysis helped improve the mechanistic understanding of transient algae growth and bioproducts formation under environmental variations and could be applied to optimize biofuel and biomass production.


Asunto(s)
Microalgas , Biomasa , Metabolismo de los Lípidos , Lípidos , Nitrógeno , Reproducibilidad de los Resultados
8.
Skinmed ; 16(6): 379-383, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30575505

RESUMEN

Exposure to ultraviolet light is a recognized modifiable risk factor for melanoma. Melanoma patients were more likely to practice sun-protective behaviors after their diagnosis. But it is not known how long these sun-protective behaviors will sustain. We aim to evaluate if sun-protective behaviors and likelihood of recent sunburn differ according to time elapsed since the melanoma diagnosis using the U.S. National Health and Nutrition Examination Survey (NHANES) database. Data in the NHANES cycle years 2003-2006 and 2010-2012 were analyzed. The relationship of sun-protective behaviors and likelihood of sunburns with the time since a melanoma diagnosis was evaluated and also adjusted for possible confounding factors such as age, gender, and skin reaction to the sun. A total of 34 participants with previous melanoma provided responses to their current sun-protective behaviors and recent occurrence of sunburns. The control group consisted of 13,871 participants who never had any diagnoses of malignancies. The control and the non-recent diagnosis groups were more likely to have sunburns but less likely to engage in consistent sun-protective behaviors compared to the recent diagnosis group. A multivariate regression model showed a 1.17 increased odds of having a recent sunburn for each additional year elapsed since a melanoma diagnosis ( p = 0.046). In our study, those with a melanoma diagnosis in the non-recent past were more likely to have sunburns and less likely to sun protect. More can definitely be done to educate and cultivate sun-protective behaviors among the U.S. population.


Asunto(s)
Conductas Relacionadas con la Salud , Melanoma/prevención & control , Melanoma/psicología , Recurrencia Local de Neoplasia/prevención & control , Neoplasias Cutáneas/prevención & control , Neoplasias Cutáneas/psicología , Quemadura Solar/prevención & control , Adulto , Estudios Transversales , Femenino , Humanos , Masculino , Melanoma/diagnóstico , Persona de Mediana Edad , Encuestas Nutricionales , Estudios Retrospectivos , Neoplasias Cutáneas/diagnóstico
9.
Inorg Chem ; 56(14): 7998-8006, 2017 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-28654240

RESUMEN

A series of dinuclear aluminum (Al2Pyr2) complexes bridged by two pyrazole ligands were synthesized, and their catalytic activity toward ring-opening polymerization of ε-caprolactone (CL) was investigated. Different types of the Al-N-N-Al-N-N skeletal ring were found among these Al2Pyr2 complexes. The butterfly form, LThio2Al2Me4, exerted the highest catalytic activity for CL polymerization. κ2-CL coordination with both Al centers within the butterfly form LThio2Al2Me4 facilitates the initiation process. Generally speaking, the Al2Pyr2 complexes exhibited substantially higher catalytic activity for CL polymerization than literature examples such as ß-diketiminate- or traiaza-bearing aluminum complexes. In fact, the Al2Pyr2 complexes can even carry out CL polymerization at room temperature.

10.
Opt Express ; 24(10): A832-45, 2016 May 16.
Artículo en Inglés | MEDLINE | ID: mdl-27409956

RESUMEN

In this work, we present the result of nickel (Ni)-based metamaterial perfect absorbers (MPA) with ultra-broadband close-to-one absorbance. The experimental broadband characteristic is significantly improved over the past effort on metamaterial perfect absorbers. An in-depth physical picture and quantitative analysis is presented to reveal the physical origin of its ultrabroadband nature. The key constituent is the cancellation of the reflected wave using ultra-thin, moderate-extinction metallic films. The ultra-thin metal thickness can reduce the reflection as the optical field penetrates through the metallic films. This leads to minimal reflection at each ultra-thin metal layer, and light is penetrating into the Ni/SiO2 stacking. More intuitively, when the layer thickness is much smaller than the photon wavelength, the layer is essentially invisible to the photons. This results in absorption in the metal thin-film through penetration while there is minimal reflection by the metal film. More importantly, the experimental evidence for omni-directionality and polarization-insensitivity are established for the proposed design. Detailed measurement is conducted. Due to the ultrathin metal layers and the satisfactory tolerance in dielectric thickness, the broadband absorption has minimal degradation at oblique incidence. Such a wide angle, polarization-insensitive, ultra-broadband MPA can be very promising in the future, and the optical physics using sub-skin-depth metal film can also facilitate miniaturized high-performance nano-photonic devices.

11.
Opt Express ; 24(2): A414-23, 2016 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-26832593

RESUMEN

In this work, we investigate blade-coated organic interlayers at the rear surface of hybrid organic-silicon photovoltaics based on two small molecules: Tris(8-hydroxyquinolinato) aluminium (Alq(3)) and 1,3-bis(2-(4-tert-butylphenyl)-1,3,4-oxadiazol-5-yl) benzene (OXD-7). In particular, soluble Alq(3) resulting in a uniform thin film with a root-mean-square roughness < 0.2nm is demonstrated for the first time. Both devices with the Alq(3) and OXD-7 interlayers show notable enhancement in the open-circuit voltage and fill-factor, leading to a net efficiency increase by over 2% from the reference, up to 11.8% and 12.5% respectively. The capacitance-voltage characteristics confirm the role of the small-molecule interlayers resembling a thin interfacial oxide layer for the Al-Si Schottky barrier to enhance the built-in potential and facilitate charge transport. Moreover, the Alq(3) interlayer in optimized devices exhibits isolated phases with a large surface roughness, in contrast to the OXD-7 which forms a continuous uniform thin film. The distinct morphological differences between the two interlayers further suggest different enhancement mechanisms and hence offer versatile functionalities to the advent of hybrid organic-silicon photovoltaics.

12.
Inorg Chem ; 55(4): 1642-50, 2016 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-26828704

RESUMEN

A series of titanium (Ti) complexes bearing hydrazine-bridging Schiff base ligands were synthesized and investigated as catalysts for the ring-opening polymerization (ROP) of L-lactide (LA). Complexes with electron withdrawing or steric bulky groups reduced the catalytic activity. In addition, the steric bulky substituent on the imine groups reduced the space around the Ti atom and then reduced LA coordination with Ti atom, thereby reducing catalytic activity. All the dinuclear Ti complexes exhibited higher catalytic activity (approximately 10-60-fold) than mononuclear L(Cl-H)-TiOPr2 did. The strategy of bridging dinuclear Ti complexes with isopropoxide groups in the ROP of LA was successful, and adjusting the crowded heptacoordinated transition state by the bridging isopropoxide groups may be the key to our successful strategy.

13.
Nanotechnology ; 27(42): 425401, 2016 Oct 21.
Artículo en Inglés | MEDLINE | ID: mdl-27632684

RESUMEN

In this work, we demonstrate homogeneously distributed In0.3Ga0.7N/GaN quantum disks (QDs), with an average diameter below 10 nm and a high density of 2.1 × 10(11) cm(-2), embedded in 20 nm tall nanopillars. The scalable top-down fabrication process involves the use of self-assembled ferritin bio-templates as the etch mask, spin coated on top of a strained In0.3Ga0.7N/GaN single quantum well (SQW) structure, followed by a neutral beam etch (NBE) method. The small dimensions of the iron cores inside ferritin and nearly damage-free process enabled by the NBE jointly contribute to the observation of photoluminescence (PL) from strain-relaxed In0.3Ga0.7N/GaN QDs at 6 K. The large blueshift of the peak wavelength by over 70 nm manifests a strong reduction of the quantum-confined Stark effect (QCSE) within the QD structure, which also agrees well with the theoretical prediction using a 3D Schrödinger equation solver. The current results hence pave the way towards the realization of large-scale III-N quantum structures using the combination of bio-templates and NBE, which is vital for the development of next-generation lighting and communication devices.

14.
J Drugs Dermatol ; 15(6): 727-32, 2016 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-27272080

RESUMEN

BACKGROUND: Photodynamic therapy (PDT) using topical application of aminolevulinic acid (ALA) is an effective treatment for acne vulgaris. However, there is no clear consensus on the treatment regime in Asians.
AIM: To determine the efficacy, safety and tolerability of 5% ALA PDT in the treatment of truncal acne in Asians.
METHODS: Patients with truncal acne were treated with 5%-ALA under occlusion for 3 hours. All were subsequently treated with a red light source at wavelength 630 nm and an irradiance of 38mW/cm2 giving a total dose of 37 J/cm2. The numbers of acne lesions were recorded at baseline and regular intervals after treatment together with any adverse effects.
RESULTS: Fifteen patients were recruited. Overall, there was a 64.2% reduction in the inflammatory lesions count and a 24.3% reduction in the non-inflammatory lesions count at the end of the 12 weeks follow-up. Both mean lesions counts were significantly lower than baseline at all follow-up time points with paired t tests (all P values <0.05). Pain was well tolerated among our patients.
CONCLUSION: A single treatment session of 5%-ALA PDT was effective for the treatment of truncal acne with little side effects and acceptable in our Asian patients.

J Drugs Dermatol. 2016;15(6):727-732.


Asunto(s)
Acné Vulgar/diagnóstico , Acné Vulgar/tratamiento farmacológico , Ácido Aminolevulínico/administración & dosificación , Pueblo Asiatico , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes/administración & dosificación , Administración Tópica , Adolescente , Adulto , Ácido Aminolevulínico/química , Composición de Medicamentos , Femenino , Estudios de Seguimiento , Humanos , Masculino , Fármacos Fotosensibilizantes/química , Torso/patología , Adulto Joven
15.
Pediatr Dermatol ; 33(1): 62-8, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-26645992

RESUMEN

BACKGROUND: Neonatal blue light phototherapy (NBLP) is an established method of managing neonatal hyperbilirubinemia. Approximately 5% of newborns are exposed to NBLP. Evidence of whether NBLP predisposes to the development of melanocytic nevi later in life has been conflicting. OBJECTIVES: The goal of the current study was to conduct a systematic review and meta-analysis to quantitatively assess the effect of NBLP on melanocytic nevus count. METHODS: We searched for observational studies in Medline, EMBASE, and the Cochrane Central Register from their inception to April 15, 2015. Meta-analysis of Observational Studies in Epidemiology guidelines were followed. DerSimonian and Laird random-effects models were used to calculate the weighted mean difference (WMD). Publication bias was assessed using a funnel plot and the Egger's test. RESULTS: Five studies with a total of 2,921 subjects were included, of whom 642 underwent NBLP. With random-effects modeling, those who had previous NBLP did not have a significantly higher mean number of melanocytic nevi (WMD = 0.32 [95% confidence interval -0.67, 1.31], p = 0.53). Visual inspection of the funnel plot suggested potential publication bias, although the Egger's test (p = 0.09) indicated no small-study effect. CONCLUSION: There was no evidence that prior NBLP exposure significantly increased the number of melanocytic nevi. Available evidence has not revealed any cause for major concern for NBLP. Other risk factors such as exposure to sunlight, childhood history of sunburn, and fair skin complexion might play a greater role in the development of melanocytic nevi in childhood.


Asunto(s)
Nevo Pigmentado/etiología , Fototerapia/efectos adversos , Neoplasias Cutáneas/etiología , Femenino , Humanos , Hiperbilirrubinemia/terapia , Recién Nacido , Masculino , Nevo Pigmentado/patología , Factores de Riesgo , Neoplasias Cutáneas/patología
16.
J Cutan Med Surg ; 20(4): 327-33, 2016 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-26316538

RESUMEN

BACKGROUND: Psoriasis is known to be associated with metabolic syndrome, a well-established risk factor for ischemic heart disease and stroke. Emerging evidence indicates that psoriasis is an independent risk factor for cardiovascular disease and stroke. OBJECTIVE: To evaluate whether psoriasis is independently associated with myocardial infarction (MI), ischemic heart disease (MI, angina pectoris, or coronary heart disease), and stroke, we conducted a cross-sectional study using the US National Health and Nutrition Examination Survey (NHANES) database. METHODS: Data on clinical history of psoriasis, MI, angina pectoris, coronary heart disease, and stroke from the questionnaire as well as laboratory parameters on serum lipid and uric acid levels in the cycle years 2003-2006 and 2009-2012 were analyzed. Multivariate analysis with logistic regression modelling was performed with the aforementioned cardiovascular events or stroke as the dependent variables and with risk factors such as age, gender, ethnic group, current smoking status, alcohol consumption, metabolic syndrome, hyperuricemia, and psoriasis as independent variables. RESULTS: There were 520 cases of psoriasis, and 108 of them had metabolic syndrome (20.8%). Well-established cardiovascular risk factors such as age, gender, ethnic group, smoking, alcohol consumption, metabolic syndrome, and hyperuricemia were also found to have significant associations with MI and ischemic heart disease (all P values <.001). Psoriatic patients were at significantly higher risks of developing MI (odds ratio [OR] 2.24; 95% CI: 1.27-3.95; P = .005) and ischemic heart disease (OR 1.90; 95% CI: 1.18-3.05; P = .008), but not stroke (OR 1.01; 95% CI: 0.48-2.16; P = .744), after adjustment was made for major cardiovascular risk factors. CONCLUSION: This study provides epidemiological evidence that psoriasis may be independently associated with the development of MI and ischemic heart disease. Physicians should be cognizant of any underlying cardiovascular risk factors, especially among psoriatic patients with metabolic syndrome, and manage them according to national guidelines.


Asunto(s)
Enfermedades Cardiovasculares/epidemiología , Psoriasis/complicaciones , Adulto , Enfermedades Cardiovasculares/diagnóstico , Estudios Transversales , Bases de Datos Factuales , Femenino , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Encuestas Nutricionales , Oportunidad Relativa , Estudios Retrospectivos , Factores de Riesgo , Estados Unidos/epidemiología , Adulto Joven
17.
Opt Express ; 23(11): 14344-50, 2015 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-26072798

RESUMEN

The photodesorption kinetics of graphene with various UV laser power is studied by conductance response. Analytical expressions of the power-dependent photodesorption kinetics of graphene in ambience are derived. The photodesorption time constant τd, steady current, and magnitude of modulation current, can be expressed as functions of the adsorption time constant τa, desorption cross section σ, and photon flux density. Under illumination the steady occupation ratio of adsorbed O2 on graphene is equal to τd/τa. It is suggested that the photodesorption of O2 on graphene is attributed the injection of photogenerated hot electrons and is restricted by the density of antibonding states of O2.

18.
Opt Express ; 23(3): A106-17, 2015 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-25836236

RESUMEN

Metallic back reflectors has been used for thin-film and wafer-based solar cells for very long time. Nonetheless, the metallic mirrors might not be the best choices for photovoltaics. In this work, we show that solar cells with all-dielectric reflectors can surpass the best-configured metal-backed devices. Theoretical and experimental results all show that superior large-angle light scattering capability can be achieved by the diffuse medium reflectors, and the solar cell J-V enhancement is higher for solar cells using all-dielectric reflectors. Specifically, the measured diffused scattering efficiency (D.S.E.) of a diffuse medium reflector is >0.8 for the light trapping spectral range (600nm-1000nm), and the measured reflectance of a diffuse medium can be as high as silver if the geometry of embedded titanium oxide(TiO(2)) nanoparticles is optimized. Moreover, the diffuse medium reflectors have the additional advantage of room-temperature processing, low cost, and very high throughput. We believe that using all-dielectric solar cell reflectors is a way to approach the thermodynamic conversion limit by completely excluding metallic dissipation.

19.
Opt Express ; 23(7): A204-10, 2015 Apr 06.
Artículo en Inglés | MEDLINE | ID: mdl-25968786

RESUMEN

The hybrid white light-emitting didoes (LED) with polyfluoren (PFO) polymer and quantum dot (QD) was investigated using dispensing method at the different correlated color temperature (CCT) for cool and warm color temperature. This result indicates that the hybrid white LED device has the higher luminous efficiency than the convention one, which could be attributed to the increased utilization rate of the UV light. Furthermore, the CIE 1931 coordinate of high quality white hybrid LED with different CCT range from 3000K to 9000K is demonstrated. Consequently, the angular-dependent CCT and the thermal issue of the hybrid white LED device were also analyzed in this study.

20.
Inorg Chem ; 54(23): 11292-8, 2015 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-26593231

RESUMEN

A series of Al complexes bearing Schiff base and thio-Schiff base ligands were synthesized, and their application for the ring-opening polymerization of ε-caprolactone (CL) and l-lactide (LA) was studied. It was found that steric effects of the ligands caused higher polymerization rate and most importantly the Al complexes with N,S-Schiff base showed significantly higher polymerization rate than Al complexes with N,O-Schiff base (5-12-fold for CL polymerization and 2-7-fold for LA polymerization). The reaction mechanism of CL polymerization was investigated by density functional theory (DFT). The calculations predicted a lower activation energy for a process involved with an Al complex bearing an N,S-Schiff base ligand (17.6 kcal/mol) than for that of an Al complex bearing an N,O-Schiff base ligand (19.0 kcal/mol), and this magnitude of activation energy reduction is comparable to the magnitude of rate enhancement observed in the experiment. The reduction of activation energy was attributed to the catalyst-substrate destabilization effect. Using a sulfur-containing ligand to decrease the activation energy in the ring-opening polymerization process may be a new strategy to design a new Al complex with high catalytic activity.

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