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1.
Nephron ; 143(2): 128-132, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31394546

RESUMEN

A 31-year-old woman presented at the emergency room after experiencing colic pain in the right iliac fossa for 5 days. She had previously consulted another center, where deterioration of renal function had been identified and abdominal computed tomography (CT) angiography had shown a dissection of the right renal artery, with areas suggestive of infarction in the right kidney, as well as an aneurysm in the left renal artery and a smaller left kidney. The patient had no relevant family or personal history except posttraumatic carotid-cavernous fistula in 2014, which had been treated with embolization. In our hospital, the patient was hypertensive and acute renal failure was confirmed, accompanied by an increase in lactate dehydrogenase and isomorphic microhematuria. After a new CT Scan, in addition to the lesions described in the renal arteries, another aneurysm in the splenic artery and an aneurysm of the right femoral artery were identified. Antihypertensive treatment was initiated with calcium antagonists and anticoagulation. Subsequent renal arteriography confirmed the dissection of the right renal artery, which could not be repaired, and a coated stent was placed in the left renal artery to exclude the aneurysm. The splenic artery lesion was treated 2 months later. The etiological diagnosis in this young woman was challenging. The presence of visceral aneurysms suggested a differential diagnosis comprising fibromuscular dysplasia, vasculitis, and collagenopathies. Using a multidisciplinary approach and directed anamnesis, the presence of frequent sprains, joint hypermobility, and skin fragility was confirmed. Blood immunology and CT angiography including the thoracic and cervical territories were normal. Echocardiography revealed tricuspid insufficiency. All these data suggested the presence of a collagen-like Ehlers-Danlos syndrome (vascular form). The diagnosis was confirmed by the genetic study, which showed a pathogenic mutation in the COL3A1 gene. Currently, the patient is asymptomatic with recovered renal function following treatment with a beta-blocker and antiplatelet therapy.


Asunto(s)
Aneurisma Disecante/diagnóstico , Síndrome de Ehlers-Danlos/diagnóstico , Displasia Fibromuscular/diagnóstico , Arteria Renal , Adulto , Aneurisma Disecante/diagnóstico por imagen , Aneurisma Disecante/genética , Colágeno Tipo III/genética , Angiografía por Tomografía Computarizada , Análisis Mutacional de ADN , Diagnóstico Diferencial , Síndrome de Ehlers-Danlos/diagnóstico por imagen , Síndrome de Ehlers-Danlos/genética , Femenino , Humanos , Arteria Renal/diagnóstico por imagen
2.
J Chem Theory Comput ; 13(12): 6061-6067, 2017 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-29083915

RESUMEN

We present a time-dependent density functional theory (TDDFT) study of the optical gaps of light-emitting nanomaterials, namely, pristine and heavily B- and P-codoped silicon crystalline nanoparticles. Twenty DFT exchange-correlation functionals sampled from the best currently available inventory such as hybrids and range-separated hybrids are benchmarked against ultra-accurate quantum Monte Carlo results on small model Si nanocrystals. Overall, the range-separated hybrids are found to perform best. The quality of the DFT gaps is correlated with the deviation from Koopmans' theorem as a possible quality guide. In addition to providing a generic test of the ability of TDDFT to describe optical properties of silicon crystalline nanoparticles, the results also open up a route to benchmark-quality DFT studies of nanoparticle sizes approaching those studied experimentally.

3.
Pharm Dev Technol ; 21(6): 688-97, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-26017851

RESUMEN

CONTEXT: Although tablet coating processes are widely used in the pharmaceutical industry, they often lack adequate robustness. Up-scaling can be challenging as minor changes in parameters can lead to varying quality results. OBJECTIVE: To select critical process parameters (CPP) using retrospective data of a commercial product and to establish a design of experiments (DoE) that would improve the robustness of the coating process. MATERIALS AND METHODS: A retrospective analysis of data from 36 commercial batches. Batches were selected based on the quality results generated during batch release, some of which revealed quality deviations concerning the appearance of the coated tablets. The product is already marketed and belongs to the portfolio of a multinational pharmaceutical company. RESULTS: The Statgraphics 5.1 software was used for data processing to determine critical process parameters in order to propose new working ranges. DISCUSSION AND CONCLUSIONS: This study confirms that it is possible to determine the critical process parameters and create design spaces based on retrospective data of commercial batches. This type of analysis is thus converted into a tool to optimize the robustness of existing processes. Our results show that a design space can be established with minimum investment in experiments, since current commercial batch data are processed statistically.


Asunto(s)
Química Farmacéutica/métodos , Comprimidos Recubiertos/síntesis química , Química Farmacéutica/normas , Estudios Retrospectivos , Comprimidos Recubiertos/normas
4.
Nat Commun ; 6: 7783, 2015 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-26205309

RESUMEN

Electrically driven single-photon emitting devices have immediate applications in quantum cryptography, quantum computation and single-photon metrology. Mature device fabrication protocols and the recent observations of single defect systems with quantum functionalities make silicon carbide an ideal material to build such devices. Here, we demonstrate the fabrication of bright single-photon emitting diodes. The electrically driven emitters display fully polarized output, superior photon statistics (with a count rate of >300 kHz) and stability in both continuous and pulsed modes, all at room temperature. The atomic origin of the single-photon source is proposed. These results provide a foundation for the large scale integration of single-photon sources into a broad range of applications, such as quantum cryptography or linear optics quantum computing.

5.
Nat Mater ; 13(2): 151-6, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24240243

RESUMEN

Over the past few years, single-photon generation has been realized in numerous systems: single molecules, quantum dots, diamond colour centres and others. The generation and detection of single photons play a central role in the experimental foundation of quantum mechanics and measurement theory. An efficient and high-quality single-photon source is needed to implement quantum key distribution, quantum repeaters and photonic quantum information processing. Here we report the identification and formation of ultrabright, room-temperature, photostable single-photon sources in a device-friendly material, silicon carbide (SiC). The source is composed of an intrinsic defect, known as the carbon antisite-vacancy pair, created by carefully optimized electron irradiation and annealing of ultrapure SiC. An extreme brightness (2×10(6) counts s(-1)) resulting from polarization rules and a high quantum efficiency is obtained in the bulk without resorting to the use of a cavity or plasmonic structure. This may benefit future integrated quantum photonic devices.

6.
Phys Rev Lett ; 110(16): 167402, 2013 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-23679637

RESUMEN

In this Letter, the photoinduced switching of the single nitrogen-vacancy (NV) center between two different charge states, negative (NV(-)) and neutral (NV(0)), is studied under resonant excitation at liquid helium temperature. We show that resonant conversion of NV(0) to NV(-) significantly improves spectral stability of the NV(-) defect and allows high fidelity initialization of the spin qubit. Based on density functional theory calculations a novel mechanism involving an Auger ionization of NV(-) and charge transfer of an electron from the valence band to NV(0) is discussed. This study provides further insight into the charge dynamics of the NV center, which is relevant for quantum information processing based on an NV(-) defect in diamond.

7.
Phys Rev Lett ; 110(4): 046804, 2013 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-25166189

RESUMEN

We present density functional and many body perturbation theory calculations of the electronic, optical, and impact ionization properties of Si nanoparticles (NPs) with core structures based on high-pressure bulk Si phases. Si particles with a BC8 core structure exhibit significantly lower optical gaps and multiple exciton generation (MEG) thresholds, and an order of magnitude higher MEG rate than diamondlike ones of the same size. Several mechanisms are discussed to further reduce the gap, including surface reconstruction and chemistry, excitonic effects, and embedding pressure. Experiments reported the formation of BC8 NPs embedded in amorphous Si and in amorphous regions of femtosecond-laser doped "black silicon." For all these reasons, BC8 nanoparticles may be promising candidates for MEG-based solar energy conversion.

8.
Phys Rev Lett ; 106(15): 157601, 2011 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-21568615

RESUMEN

The nitrogen-vacancy (NV) center in diamond is supposed to be a building block for quantum computing and nanometer-scale metrology at ambient conditions. Therefore, precise knowledge of its quantum states is crucial. Here, we experimentally show that under usual operating conditions the NV exists in an equilibrium of two charge states [70% in the expected negative (NV-) and 30% in the neutral one (NV0)]. Projective quantum nondemolition measurement of the nitrogen nuclear spin enables the detection even of the additional, optically inactive state. The nuclear spin can be coherently driven also in NV0 (T1≈90 ms and T2≈6 µs).

9.
J Environ Manage ; 92(4): 1091-6, 2011 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-21183273

RESUMEN

It is a fact that the rapid increase of biodiesel production over the last years has resulted in the generation of large and constant amounts of glycerine, which is causing an oversupply problem. Since glycerine is a biodegradable organic compound exempt of nitrogen, it can be applied as a co-substrate in the anaerobic digestion process of pig manure (PM). In order to analyze the feasibility of a mixture of pig manure and glycerine in anaerobic processes and to define the effect originated by the nitrogen limitation when large amounts of glycerine are added, several biodegradability batch tests were performed with different mixtures. These were named as: 100% PM, 80% PM, 60% PM, 40% PM and 20% PM, in pig manure wet weight-basis. Furthermore, a modified model based on anaerobic digestion model no.1 (ADM1) was used to simulate the methane production profiles for the mixtures tested. Specifically, both experimental and model results show the power of the co-digestion technology. In particular, the mixture of 80% PM produced the highest methane production with 215 mL CH(4) g(-1) COD, almost 125% more methane than when pig manure was mono-digested. In contrast, the one with 20% PM was clearly inhibited by the volatile fatty acid due to the low nitrogen concentration of the mixture. In addition, the specific methane production predicted by the model was in good agreement with the experimental results, although in some samples the shape of the profiles did not match perfectly. Moreover, the modified ADM1 appears to be a useful tool to predict the methane production and the limitations related to the lack/excess of nitrogen during the co-digestion process of pig manure and glycerine.


Asunto(s)
Glicerol/metabolismo , Estiércol , Metano/análisis , Anaerobiosis , Animales , Biodegradación Ambiental , Cromatografía de Gases , Modelos Biológicos , Porcinos
10.
Urol Int ; 84(4): 400-6, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-20332612

RESUMEN

OBJECTIVES: To evaluate the efficacy and safety of Serenoa repens + selenium and lycopene (Profluss) versus S. repens alone for the treatment of category IIIa chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). PATIENTS AND METHODS: 102 patients with IIIa CP/CPPS were enrolled and randomized into two groups each to receive Profluss or S. repens alone for 8 weeks. Evaluation was based on results of the National Institutes of Health-Chronic Prostatitis Symptom Index (NIH-CPSI), IPSS, maximum peak flow rate (MPFR), and PSA measurements at baseline and at weeks 4, 8 and 8 after the end of treatment. The primary endpoint was a >50% reduction in NIH-CPSI score. Secondary endpoints evaluated were MPFR, IPSS, PSA and white blood cell count. RESULTS: No patients withdrew from the study. The mean NIH-CPSI score decreased significantly (p < 0.001) in both groups; we observed a decrease in the total score from 27.45 to 13.27 in group 1 (-51.64%) and from 27.76 to 20.62 in group 2 (-26.06%). IPSS improved significantly (p < 0.001) in both arms, but more in group 1. PSA and white blood cell count decreased significantly (p < 0.007) only in group 1. The MPFR improved more in group 1 (p < 0.005). CONCLUSION: Profluss is a triple therapy that is safe and well tolerated. It ameliorates symptoms associated with IIIa CP/CPPS.


Asunto(s)
Antiinflamatorios/uso terapéutico , Carotenoides/uso terapéutico , Dolor Pélvico/tratamiento farmacológico , Extractos Vegetales/uso terapéutico , Prostatitis/tratamiento farmacológico , Selenio/uso terapéutico , Serenoa , Adulto , Antiinflamatorios/efectos adversos , Carotenoides/efectos adversos , Enfermedad Crónica , Método Doble Ciego , Combinación de Medicamentos , Humanos , Italia , Recuento de Leucocitos , Licopeno , Masculino , Persona de Mediana Edad , Dolor Pélvico/sangre , Dolor Pélvico/fisiopatología , Dolor Pélvico/orina , Extractos Vegetales/efectos adversos , Antígeno Prostático Específico/sangre , Prostatitis/sangre , Prostatitis/fisiopatología , Prostatitis/orina , Selenio/efectos adversos , Índice de Severidad de la Enfermedad , Síndrome , Factores de Tiempo , Resultado del Tratamiento , Orina/citología , Urodinámica , Adulto Joven
11.
Water Sci Technol ; 59(6): 1153-8, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19342811

RESUMEN

The anaerobic digestion of the organic fraction of municipal solid wastes is taking increasing importance in the recent years. The main problem of some anaerobic digestion process is the large quantity of ammonia that is released, especially when high solid digestion is implemented. A fraction of the supernatant is treated and the remaining is recirculated to maintain the reactor in the optimum solids concentration. The question arising is if this recirculation stream should also be treated to improve biogas production. However, when doing the latter the quantity of ammonia inside the reactor increases too which could lead to inhibit the reactor operation. In this paper it appears that not only free ammonia affects the methanogenic fermentation but also ammonium ion concentration. Biogas production profiles are estimated using the Gompertz model. On the other hand, inhibition constants are fitted using a non-competitive inhibition model equation Thus, 50% inhibition of biomethane production was observed at level of 215 and 468 mg NH3_N/L under mesophilic and thermophilic conditions. However, the methane generation under mesophilic and thermophilic conditions was reduced by 50% when ammonium ion reach concentrations of 3,860 and 5,600 mg NH4+_N/L respectively. Under mesophilic conditions, pH higher than 7 impacted the methanogens bacteria negatively. This threshold pH limit, is variable under thermophilic conditions, depending on the total ammonia concentration.


Asunto(s)
Amoníaco/química , Amoníaco/metabolismo , Eliminación de Residuos/métodos , Aguas del Alcantarillado/química , Anaerobiosis , Concentración de Iones de Hidrógeno
12.
Bioresour Technol ; 100(11): 2783-90, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-19201603

RESUMEN

Agro-residues account for a large proportion of the wastes generated around the world. There is thus a need for a model to simulate the anaerobic digestion processes used in their treatment. We have developed model based on ADM1, to be applied to agro-wastes. We examined and tested the biodegradability of apple, pear, orange, rape, sunflower, pig manure and glycerol wastes to be used as the basis for feeding the model. Moreover, the fractions of particulate COD (X(c)) were calculated, and the disintegration constant was obtained from biodegradability profiles, considering disintegration to be the limiting process. The other kinetic and stoichiometric parameters were taken from the ADM1 model. The model operating under mono-substrate and co-substrate conditions was then validated with batch tests. At the same time the model was validated on a continuous anaerobic reactor operating with pig manure at lab scale. In both cases the correlation between the model and the experimental results was satisfactory. We conclude that the anaerobic digestion model is a reliable tool for the design and operation of plants in which agro-wastes are treated.


Asunto(s)
Agricultura/métodos , Bacterias Anaerobias/metabolismo , Reactores Biológicos/microbiología , Residuos Industriales/prevención & control , Modelos Biológicos , Aguas del Alcantarillado/microbiología , Administración de Residuos/métodos , Simulación por Computador , Programas Informáticos
13.
Water Sci Technol ; 58(2): 467-72, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18701802

RESUMEN

This paper focuses on the study of high ammonium concentrated wastewater with SBR reactors. Four type of wastewaters, landfill leachates (T=20 degrees C) and the reject water (T=35 degrees C) coming from mesophilic anaerobic digesters of sewage sludge, pig slurry and organic fraction of municipal solid waste (OFMSW), were studied in four SBR during 6 months. The removal of nitrogen was done in all the cases with nitrification/denitrification via nitrite obtaining high removal nitrogen conversions for the three types of reject water (0.75-0.85 kg N day(-1) m(-3)) and lower for landfill leachates due to temperature requirements (0.3 kg N day(-1) m(-3)).


Asunto(s)
Reactores Biológicos , Compuestos de Amonio Cuaternario/química , Purificación del Agua/instrumentación , Purificación del Agua/métodos , Agricultura , Anaerobiosis , Animales , Nitritos , Aguas del Alcantarillado/química , Porcinos , Temperatura , Eliminación de Residuos Líquidos/instrumentación , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua
14.
Water Environ Res ; 80(3): 197-204, 2008 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-18419007

RESUMEN

An efficient biological treatment to treat reject water from anaerobic digestion of wastewater sludge is the SHARON denitrification process, which takes place in a chemostat reactor, where aerobic/anoxic periods are alternated under specific hydraulic retention time (HRT) and temperature conditions that favor ammonium oxidizers growth and ensure the total washout of nitrite oxidizers, achieving the biological nitrogen removal over nitrite. An optimized performance of this process to treat Spanish reject water was obtained using methanol and working at an HRT of 2 days, 33 degrees C, and cycle length of 2 hours. Supernatant of hydrolyzed primary sludge was tested to denitrify. Because biochemical oxygen demand was not extremely high in the primary sludge, the fluid dynamics of the system were changed, with respect to the strategy with methanol, but maintaining the reject water influent flowrate. The use of hydrolyzed primary sludge improved the process efficiency, because the alkalinity present in the primary sludge buffered the process until an optimum pH range.


Asunto(s)
Nitritos/metabolismo , Nitrógeno/metabolismo , Eliminación de Residuos Líquidos/métodos , Purificación del Agua/métodos , Aerobiosis , Anaerobiosis , Biodegradación Ambiental , Reactores Biológicos , Humanos
15.
Bioresour Technol ; 99(13): 5722-30, 2008 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-18068357

RESUMEN

The supernatant from mesophilic anaerobic digestion of piggery wastewater is characterised by a high amount of COD (4.1 g COD L(-1)), ammonium (2.3g NH(4)(+)-NL(-1)) and suspended solids (2.5 g SS L(-1)). This effluent can be efficiently treated by means of a Sequencing Batch Reactor (SBR) strategy for biological COD, SS and nitrogen removal including a Coagulation/Flocculation step. Total COD and SS reduction yields higher than 66% and 74%, respectively, and a total nitrogen removal (via nitrite) of more than 98% were reached when working with HRT 2.7 days, SRT 12 days, temperature 32 degrees C, three aerobic/anoxic periods, without external control of pH and under limited aeration flow. The inhibition of nitrite oxidizing biomass was achieved by the working free ammonia concentration and the restricted air supply (dissolved oxygen concentration below 1 mg O(2)L(-1)). Since a part of the total COD was colloidal and/or refractory, a Coagulation/Flocculation step was implemented inside the SBR operating strategy to meet a suitable effluent quality to be discharged. Several Jar-Tests demonstrated that the optimal concentration of FeCl(3) was 800 mg L(-1). A respirometric assay showed that this coagulant dosage did not affect the biological activity of nitrifying/denitrifying biomass.


Asunto(s)
Biomasa , Aguas del Alcantarillado , Porcinos , Eliminación de Residuos Líquidos , Anaerobiosis , Crianza de Animales Domésticos/economía , Animales , Costos y Análisis de Costo , Floculación , Aceites Combustibles , Transportes/economía , Estados Unidos , Contaminantes del Agua/análisis
16.
Environ Technol ; 28(5): 565-71, 2007 May.
Artículo en Inglés | MEDLINE | ID: mdl-17615965

RESUMEN

An optimal sequencing batch reactor (SBR) strategy is proposed for Biological Nitrogen Removal (BNR) via nitrite of reject water (800-900 NH4+-N mg l(-1)) from mesophilic (35 degrees C) anaerobic sludge digester of a Spanish Municipal Wastewater Treatment Plant (WWTP). Two lab-scale SBR with control of temperature were studied with external COD addition for denitrification which was necessary due to the lack of readily biodegradable carbon source. Process kinetics were compared through the specific Ammonium Uptake Rate (sAUR) finding the appropriate operational sequences when working at 32 degrees C and 8 hour cycle length. Every operating cycle was carried out with a sludge retention time of 11 days, hydraulic retention time around 1 day and 2500+/-250 mg VSS l(-1). In order to avoid nitrate formation and thus save costs, the oxygen concentration was maintained below 1 mg V1 during aerobic periods and pH remained within an optimal range (7.5-9) alternating different aerobic-anoxic subcycles inside the operational cycle. With this strategy, the range of alkalinity could be controlled avoiding the addition of external additives and nitrite accumulation was prevented. Therefore, the reached sAUR was 22 mg NH4+-N g)-1) VSS h(-1) and the total nitrogen removal was 0.8 kg N(d m(3))(-1).


Asunto(s)
Nitratos , Nitritos , Nitrógeno/aislamiento & purificación , Aguas del Alcantarillado/microbiología , Purificación del Agua/métodos , Aerobiosis , Amoníaco/química , Amoníaco/metabolismo , Carbono/química , Carbono/metabolismo , Concentración de Iones de Hidrógeno , Cinética , Nitratos/química , Nitratos/metabolismo , Nitritos/química , Nitritos/metabolismo , Nitrógeno/metabolismo , Oxígeno/química , Oxígeno/metabolismo , Aguas del Alcantarillado/química , España , Temperatura , Purificación del Agua/instrumentación
17.
Environ Technol ; 28(2): 173-6, 2007 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-17396411

RESUMEN

A comparison between three feasible ways of developing Biological Nitrogen Removal (BNR) via nitrite to treat real reject water of 800-900 mg NH4(+)-N l(-1) is proposed. A Sequencing Batch Reactor (SBR) and a chemostat SHARON (Single reactor High activity Ammonium Removal Over Nitrite) continuous reactor were operated. In the SBR operation 0.8 kg N (d m3)(-1) was achieved, whereas in SHARON/denitrification the removal reached was 0.4 kg N (d m3)(-1). SHARON was also developed with partial nitrification of ammonium in order to obtain a stream ready for Anammox (Anaerobic Ammonia Oxidation) process obtaining an effluent with an average composition of 400 mg NO2(-)-N l(-1) and 350 mg NH4(-)-N l(-1).


Asunto(s)
Nitritos/metabolismo , Eliminación de Residuos Líquidos/métodos , Reactores Biológicos , Nitratos/análisis , Nitratos/metabolismo , Nitritos/análisis , Compuestos de Amonio Cuaternario/análisis , Compuestos de Amonio Cuaternario/metabolismo
18.
Bioresour Technol ; 98(11): 2065-75, 2007 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-17292605

RESUMEN

The aim of this study was the operation and model description of a sequencing batch reactor (SBR) for biological nitrogen removal (BNR) from a reject water (800-900 mg NH(4)(+)-NL(-1)) from a municipal wastewater treatment plant (WWTP). The SBR was operated with three cycles per day, temperature 30 degrees C, SRT 11 days and HRT 1 day. During the operational cycle, three alternating oxic/anoxic periods were performed to avoid alkalinity restrictions. Oxygen supply and working pH range were controlled to achieve the BNR via nitrite, which makes the process more economical. Under steady state conditions, a total nitrogen removal of 0.87 kg N (m(3)day)(-1) was reached. A four-step nitrogen removal model was developed to describe the process. This model enlarges the IWA activated sludge models for a more detailed description of the nitrogen elimination processes and their inhibitions. A closed intermittent-flow respirometer was set up for the estimation of the most relevant model parameters. Once calibrated, model predictions reproduced experimental data accurately.


Asunto(s)
Reactores Biológicos , Nitritos/química , Nitrógeno/química , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Bacterias/crecimiento & desarrollo , Bacterias/metabolismo , Biodegradación Ambiental , Biomasa , Calibración , Concentración de Iones de Hidrógeno , Cinética , Modelos Teóricos , Nitritos/metabolismo , Nitrógeno/metabolismo , Oxígeno/química , Agua/química , Microbiología del Agua , Contaminantes Químicos del Agua/metabolismo , Purificación del Agua/economía , Purificación del Agua/instrumentación
19.
Environ Technol ; 27(8): 891-9, 2006 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-16972385

RESUMEN

Treating the supernatant (reject water) from an anaerobic sludge digestion (800-1200 mg NH4(+)-N l(-1)) may be a good solution for meeting local requirements. As reject water represents 0.6% of the total wastewater influent flow and contains 10-30% of the total N it is recirculated to the head plant. In this study, a lab-scale start-up of biological nitrification/denitrification process to treat reject water was developed in a sequencing batch reactor. Sludge acclimation to the denitrification process was quite fast (6-7 days) for both NO2(-)-N and NO3(-)-N, whereas in nitrification it was slower (20 days). The use of a sequencing batch reactor to treat reject water produced a complete biological reduction of the NH4(+)-N via nitrite, working with sludge age of 15 days, hydraulic retention time of 1.3 days, temperature of 28 degrees C, pH between 7-8.5 and biomass concentration around 3500 mg VSS l(-1). Specific efficiencies were 14 mg NH4(+)-N (g VSS h(-1)) and 30 mg NO2(-)-N (g VSS h)(-1).


Asunto(s)
Reactores Biológicos , Aguas del Alcantarillado/química , Anaerobiosis , Bacterias/metabolismo , Concentración de Iones de Hidrógeno , Nitrógeno/análisis , Agua/química , Purificación del Agua
20.
Phys Rev Lett ; 96(14): 145501, 2006 Apr 14.
Artículo en Inglés | MEDLINE | ID: mdl-16712089

RESUMEN

The metastability of vacancies was theoretically predicted for several compound semiconductors alongside their transformation into the antisite-vacancy pair counterpart; however, no experiment to date has unambiguously confirmed the existence of antisite-vacancy pairs. Using electron paramagnetic resonance and first principles calculations we identify the S15 center as the carbon antisite-vacancy pair in the negative charge state (C(Si)V-(C)) in 4H-SiC. We suggest that this defect is a strong carrier-compensating center in n-type or high-purity semi-insulating SiC.

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