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1.
Plant J ; 119(1): 577-594, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38576267

RESUMEN

Little millet (Panicum sumatrense Roth ex Roem. & Schult.) is an essential minor millet of southeast Asia and Africa's temperate and subtropical regions. The plant is stress-tolerant, has a short life cycle, and has a mineral-rich nutritional profile associated with unique health benefits. We report the developmental gene expression atlas of little millet (genotype JK-8) from ten tissues representing different stages of its life cycle, starting from seed germination and vegetative growth to panicle maturation. The developmental transcriptome atlas led to the identification of 342 827 transcripts. The BUSCO analysis and comparison with the transcriptomes of related species confirm that this study presents high-quality, in-depth coverage of the little millet transcriptome. In addition, the eFP browser generated here has a user-friendly interface, allowing interactive visualizations of tissue-specific gene expression. Using these data, we identified transcripts, the orthologs of which in Arabidopsis and rice are involved in nutrient acquisition, transport, and response pathways. The comparative analysis of the expression levels of these transcripts holds great potential for enhancing the mineral content in crops, particularly zinc and iron, to address the issue of "hidden hunger" and to attain nutritional security, making it a valuable asset for translational research.


Asunto(s)
Regulación de la Expresión Génica de las Plantas , Panicum , Transcriptoma , Transcriptoma/genética , Panicum/genética , Panicum/metabolismo , Panicum/crecimiento & desarrollo , Minerales/metabolismo , Grano Comestible/genética , Grano Comestible/crecimiento & desarrollo , Grano Comestible/metabolismo , Perfilación de la Expresión Génica
2.
Biomacromolecules ; 25(6): 3302-3311, 2024 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-38717957

RESUMEN

This study aimed to visualize the microstructures of starch hydrogels using synchrotron-based X-ray micro-computed tomography (µCT). Waxy maize starch (WMS, 3.3% amylose, db), pea starch (PS, 40.3% amylose), and high-amylose maize starch (HMS, 63.6% amylose) were cooked at 95 and 140 °C to prepare starch hydrogels. WMS and HMS failed to form a gel after 95 °C cooking and storage, while PS developed a firm gel. At 140 °C cooking, HMS of a high amylose nature was fully gelatinized and generated a rigid gel with the highest strength. Both scanning electron microscopy (SEM) and µCT revealed the unique structural features of various starch hydrogels/pastes prepared at different temperatures, which were greatly affected by the degree of swelling and dispersity of the starches. As a nondestructive method, µCT showed certain advantages over SEM, including minimal shrinkage of the hydrogels, relatively simple sample preparation, and allowing for three-dimensional reconstruction of the hydrogel microstructure. This study indicated that synchrotron-based µCT could be a useful technique in visualizing biopolymer-based hydrogels.


Asunto(s)
Hidrogeles , Almidón , Sincrotrones , Microtomografía por Rayos X , Zea mays , Hidrogeles/química , Microtomografía por Rayos X/métodos , Almidón/química , Zea mays/química , Amilosa/química , Microscopía Electrónica de Rastreo/métodos
3.
Physiol Plant ; 175(5): e14040, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37882281

RESUMEN

Balsam poplar (Populus balsamifera L.) is a widespread tree species in North America with significant ecological and economic value. However, little is known about the susceptibility of saplings to drought-induced embolism and its link to water release from surrounding xylem fibers. Questions remain regarding localized mechanisms that contribute to the survival of saplings in vivo of this species under drought. Using X-ray micro-computed tomography on intact saplings of genotypes Gillam-5 and Carnduff-9, we found that functional vessels are embedded in a matrix of water-filled fibers under well-watered conditions in both genotypes. However, water-depleted fibers started to appear under moderate drought stress while vessels remained water-filled in both genotypes. Drought-induced xylem embolism susceptibility was comparable between genotypes, and a greater frequency of smaller diameter vessels in GIL-5 did not increase embolism resistance in this genotype. Despite having smaller vessels and a total vessel number that was comparable to CAR-9, stomatal conductance was generally higher in GIL-5 compared to CAR-9. In conclusion, our in vivo data on intact saplings indicate that differences in embolism susceptibility are negligible between GIL-5 and CAR-9, and that fiber water release should be considered as a mechanism that contributes to the maintenance of vessel functional status in saplings of balsam poplar experiencing their first drought event.


Asunto(s)
Embolia , Populus , Agua , Populus/genética , Microtomografía por Rayos X , Sequías , Xilema
4.
Aging Ment Health ; 25(8): 1433-1441, 2021 08.
Artículo en Inglés | MEDLINE | ID: mdl-32223428

RESUMEN

OBJECTIVES: People who are living with dementia typically experience difficulties in completing multi-step, everyday tasks. However, digital technology such as touchscreen tablets provide a means of delivering concise personalised prompts that combine audio, text and pictures. This study was one component of a broader, mixed methods study that tested how an application (app) -based prompter running on a touchscreen tablet computer could support everyday activities in individuals with mild to moderate dementia. In this study we set out to understand the experiences of people living with dementia and their primary carer in using the prompter over a four-week period. METHOD: We collected qualitative data using semi-structured interviews from 26 dyads, composed of a person living with dementia and their carer. Dyads were interviewed at the start and end of this period. Transcripts were then analysed using thematic analysis. RESULTS: The study identified three overarching themes related to: participants' attitudes towards the technology; their judgements about how useful the prompter would be; and the emotional impact of using it. CONCLUSION: Consistent with the Technology Acceptance Model, carers and participants were influenced by their approaches to technology and determined the usefulness of the prompter according to whether it worked for them and fitted into their routines. In addition, participants' decisions about using the prompter were also determined by the extent to which doing so would impact on their self-identity.


Asunto(s)
Cuidadores , Demencia , Humanos , Tecnología
5.
IEEE Trans Robot ; 30(6): 1358-1370, 2014 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-25598763

RESUMEN

Estimation of model parameters in a dynamic system can be significantly improved with the choice of experimental trajectory. For general nonlinear dynamic systems, finding globally "best" trajectories is typically not feasible; however, given an initial estimate of the model parameters and an initial trajectory, we present a continuous-time optimization method that produces a locally optimal trajectory for parameter estimation in the presence of measurement noise. The optimization algorithm is formulated to find system trajectories that improve a norm on the Fisher information matrix (FIM). A double-pendulum cart apparatus is used to numerically and experimentally validate this technique. In simulation, the optimized trajectory increases the minimum eigenvalue of the FIM by three orders of magnitude, compared with the initial trajectory. Experimental results show that this optimized trajectory translates to an order-of-magnitude improvement in the parameter estimate error in practice.

6.
Catal Sci Technol ; 14(6): 1622-1632, 2024 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-38505507

RESUMEN

Artificial metalloenzymes (ArMs) have emerged as a promising avenue in the field of biocatalysis, offering new reactivity. However, their design remains challenging due to the limited understanding of their protein dynamics and how the introduced cofactors alter the protein scaffold structure. Here we present the structures and catalytic activity of novel copper ArMs capable of (R)- or (S)-stereoselective control, utilizing a steroid carrier protein (SCP) scaffold. To incorporate 2,2'-bipyridine (Bpy) into SCP, two distinct strategies were employed: either Bpy was introduced as an unnatural amino acid (2,2'-bipyridin-5-yl)alanine (BpyAla) using amber stop codon expression or via bioconjugation of bromomethyl-Bpy to cysteine residues. The resulting ArMs proved to be effective at catalysing an enantioselective Friedel-Crafts reaction with SCP_Q111BpyAla achieving the best selectivity with an enantioselectivity of 72% ee (S). Interestingly, despite using the same protein scaffold, different attachment strategies for Bpy at the same residue (Q111) led to a switch in the enantiopreference of the ArM. X-ray crystal structures of SCP_Q111CBpy and SCP_Q111BpyAla ArMs with bound Cu(ii) ions unveiled crucial differences in the orientation of the catalytic centre. Combining structural information, alanine scanning studies, and computational analysis shed light on the distinct active sites of the ArMs, clarifying that these active sites stabilise the nucleophilic substrate on different sides of the electrophile leading to the observed switch in enantioselectivity. This work underscores the importance of integrating structural studies with catalytic screening to unravel the intricacies of ArM behaviour and facilitate their development for targeted applications in biocatalysis.

7.
Protoplasma ; 260(5): 1303-1312, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-36890289

RESUMEN

Floral appendages display an array of shapes and sizes. Among these organs, staminodes are morphologically diverse structures that have lost the ability to produce pollen, but in some instances, they produce fertile pollen grains. In the family Cactaceae staminodes are uncommon and range from simple linear to flat to spatulate structures, but studies describing their structural attributes are scanty. This study highlights the advantages of synchrotron radiation for sample preparation and as a research tool for plant biology. It describes the internal morphology of floral parts, particularly stamen, tepal, and staminode in the Plains Prickly Pear Cactus, Opuntia polyacantha, using synchrotron radiation micro-computed tomography (SR-µCT). It also shows the different anatomical features in reconstructed three-dimensional imaging of reproductive parts and discuss the advantages of the segmentation method to detect and characterize the configuration and intricate patterns of vascular networks and associated structures of tepal and androecial parts applying SR-µCT. This powerful technology led to substantial improvements in terms of resolution allowing a more comprehensive understanding of the anatomical organization underlying the vasculature of floral parts and inception of staminodes in O. polyacantha. Tepal and androecial parts have uniseriate epidermis enclosing loose mesophyll with mucilage secretory ducts, lumen, and scattered vascular bundles. Cryptic underlying structural attributes provide evidence of a vascularized pseudo-anther conjoint with tepals. The undefined contours of staminodial appendages (pseudo-anther) amalgamated to the tepals' blurred boundaries suggest that staminodes originate from tepals, a developmental pattern supporting the fading border model of floral organ identity for angiosperms.


Asunto(s)
Flores , Opuntia , Sincrotrones , Rayos X , Flores/citología , Opuntia/citología , Imagenología Tridimensional , Polen/citología
8.
J Acoust Soc Am ; 132(3): 1325-35, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22978861

RESUMEN

The distributed point source method is commonly used to predict the complex acoustic field emitted by ultrasonic transducers. In this paper, it is presented as an alternative to conventional approaches often used when solving rough surface scattering problems. Surface shadowing and multiple scattering effects are inherently included in the mesh-free semi-analytical simulation method through matrix manipulation making it very efficient and simple to implement. Results are presented which illustrate the improvement in accuracy gained over the Kirchhoff approximation and the decrease in computational load over the finite element method, culminating in greater than an order of magnitude decrease in required simulation time. The method is applied to the practical problem of online wall thickness monitoring within corrosive environments, illustrating the variability in reflected pulse shape that could be expected from rough surfaces with similar statistics. Three commonly implemented time-of-flight algorithms are used to analyze a large number of simulated signals from which it is concluded that those based on first arrival time are more stable under increasing roughness conditions than those which are based on reflected pulse shape.


Asunto(s)
Materiales de Construcción , Modelos Teóricos , Transductores , Ultrasonido/instrumentación , Algoritmos , Simulación por Computador , Diseño de Equipo , Arquitectura y Construcción de Instituciones de Salud , Análisis de Elementos Finitos , Análisis Numérico Asistido por Computador , Reproducibilidad de los Resultados , Dispersión de Radiación , Propiedades de Superficie , Factores de Tiempo
9.
Water Sci Technol ; 65(1): 164-70, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22173421

RESUMEN

Diurnal fluctuations of metals have been observed in the South Tyne river catchment, UK, in both upland tributaries and major river reaches. Zinc exhibits the most pronounced cyclicity, with concentrations increasing during the night to a maximum near 05:00 before decreasing during the day. This trend is the inverse of pH and temperature observations, which are thought to be the predominant drivers behind the cyclicity. Photosynthetic reactions of biomass and algae alter the pH within the river systems, therefore promoting hydrous metal oxide precipitation during the daylight which consequently allows divalent cations including zinc to sorb onto them. This mechanism may be supported by direct uptake of zinc by algae and other biogeochemical reactions which combine to create large differences in zinc concentrations; during base flow zinc concentrations increased by 326% from the minima over 48 hours. Maximum concentrations are not being captured during routine water quality analysis resulting in inaccurate and misleading EQS results and total flux estimations, for example the annual total zinc flux in a small tributary increases from 17 to 76 tonnes/year when routine grab sample data are supplemented with 24-hour sampling results.


Asunto(s)
Ríos/química , Contaminantes Químicos del Agua/análisis , Zinc/análisis , Arsénico/análisis , Concentración de Iones de Hidrógeno , Metales/análisis , Temperatura , Factores de Tiempo , Reino Unido , Contaminantes Químicos del Agua/normas , Calidad del Agua , Zinc/normas
10.
Nat Commun ; 12(1): 5018, 2021 08 31.
Artículo en Inglés | MEDLINE | ID: mdl-34465789

RESUMEN

Chocolate manufacture includes a complex tempering procedure to direct the crystallization of cocoa butter towards the formation of fat crystal networks with specific polymorphism, nano- and microstructure, melting behavior, surface gloss and mechanical properties. Here we investigate the effects of adding various minor non-triglyceride lipidic components to refined cocoa butter and chocolate on their physical properties. We discover that addition of saturated phosphatidylcholine and phosphatidylethanolamine to neutralized and bleached cocoa butter or molten and recrystallized commercial chocolate at 0.1% (w/w) levels, followed by rapid cooling to 20 °C in the absence of shear, accelerates crystallization, stabilizes the desirable Form V polymorph and induces the formation of chocolate with an optimal microstructure, surface gloss and mechanical strength. Final chocolate structure and properties are comparable to those of a commercial tempered chocolate. Minor lipidic component addition represents an effective way to engineer chocolate material properties at different length scales, thus simplifying the entire tempering process.


Asunto(s)
Chocolate/análisis , Grasas de la Dieta/análisis , Aditivos Alimentarios/química , Lípidos/química , Cacao/química , Cristalización , Manipulación de Alimentos
11.
Sci Total Environ ; 750: 141693, 2021 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-32846253

RESUMEN

Extreme rainfall events are predicted to become more frequent with climate change and can have a major bearing on instream solute and pollutant transport in mineralised catchments. The Coledale Beck catchment in north-west England was subject to an extreme rainfall event in December 2015 that equated to a 1 in 200-year event. The catchment contains the UK's first passive metal mine water treatment system, and as such had been subject to intense monitoring of solute dynamics before and after commissioning. Due to this monitoring record, the site provides a unique opportunity to assess the effects of a major storm event on (1) catchment-scale solute transport, and (2) the resilience of the new and novel passive treatment system to extreme events. Monitoring suggests a modest decline in treatment efficiency over time that is not synchronous with the storm event and explained instead by changes in system hydraulic efficiency. There was no apparent flushing of the mine system during the event that could potentially have compromised treatment system performance. Analysis of metal transport in the catchment downstream of the mine suggests relatively subtle changes in instream chemistry with modest but statistically-significant reductions in zinc in the lower catchment irrespective of flow condition after the extreme event, but most parameters of interest show no significant change. Increased export of colloidal iron and aluminium is associated with major landslips in the mid-catchment after the storm and provide fresh sorption sites to attenuate dissolved zinc more rapidly in these locations, corroborated by laboratory experiments utilising site materials to investigate the attenuation/release of metals from stream and terrestrial sediments. The data are important as they show both the resilience of passive mine water treatment systems to extreme events and the importance of catchment-scale monitoring to ensure continued effectiveness of treatment initiatives after major perturbation.

12.
Water Sci Technol ; 62(8): 1937-46, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-20962411

RESUMEN

Analysis of residence time distribution (RTD) has been conducted for the UK Coal Authority's mine water treatment wetland at Lambley, Northumberland, to determine the hydraulic performance of the wetland over a period of approximately 4 years since site commissioning. The wetland RTD was evaluated in accordance with moment analysis and modelled based on a tanks-in-series (TIS) model to yield the hydraulic characteristics of system performance. Greater hydraulic performance was seen during the second site monitoring after 21 months of site operation i.e. longer hydraulic residence time to reflect overall system hydraulic efficiency, compared to wetland performance during its early operation. Further monitoring of residence time during the third year of wetland operation indicated a slight reduction in hydraulic residence time, thus a lower system hydraulic efficiency. In contrast, performance during the fourth year of wetland operation exhibited an improved overall system hydraulic efficiency, suggesting the influence of reed growth over the lifetime of such systems on hydraulic performance. Interestingly, the same pattern was found for iron (which is the primary pollutant of concern in ferruginous mine waters) removal efficiency of the wetland system from the second to fourth year of wetland operation. This may therefore, reflect the maturity of reeds for maintaining efficient flow distribution across the wetland to retain a longer residence time and significant fractions of water involved to enhance the extent of treatment received for iron attenuation. Further monitoring will be conducted to establish whether such performance is maintained, or whether efficiency decreases over time due to accumulation of dead plant material within the wetland cells.


Asunto(s)
Monitoreo del Ambiente/métodos , Compuestos Férricos/aislamiento & purificación , Minería , Modelos Teóricos , Contaminantes Químicos del Agua/aislamiento & purificación , Humedales , Compuestos Férricos/análisis , Hidrodinámica , Estaciones del Año , Factores de Tiempo , Reino Unido , Movimientos del Agua , Contaminantes Químicos del Agua/análisis
13.
J Appl Microbiol ; 106(5): 1502-11, 2009 May.
Artículo en Inglés | MEDLINE | ID: mdl-19210570

RESUMEN

AIMS: To monitor emissions of NH(3) and N(2)O during composting and link these to ammonia oxidation rates and the community structure of ammonia oxidizing bacteria (AOB). METHODS AND RESULTS: A laboratory-scale compost reactor treating organic household waste was run for 2 months. NH(3) emissions peaked when pH started to increase. Small amounts of N(2)O and CH(4) were also produced. In total, 16% and less than 1% of the initial N was lost as NH(3)-N and N(2)O-N respectively. The potential ammonia oxidation rate, determined by a chlorate inhibition assay, increased fourfold during the first 9 days and then remained high. Initially, both Nitrosospira and Nitrosomonas populations were detected using DGGE analysis of AOB specific 16S rRNA fragments. Only Nitrosomonas europaea was detected under thermophilic conditions, but Nitrosospira populations re-established during the cooling phase. CONCLUSIONS: Thermophilic conditions favoured high potential ammonia oxidation rates, suggesting that ammonia oxidation contributed to reduced NH(3) emissions. Small but significant amounts of N(2)O were emitted during the thermophilic phase. The significance of different AOBs detected in the compost for ammonia oxidation is not clear. SIGNIFICANCE AND IMPACT OF STUDY: This study shows that ammonia oxidation occurs at high temperature composting and therefore most likely reduces NH(3) emissions.


Asunto(s)
Amoníaco/metabolismo , Bacterias/metabolismo , Óxido Nitroso/metabolismo , Eliminación de Residuos/métodos , Bacterias/genética , Secuencia de Bases , Biodegradación Ambiental , Reactores Biológicos , Clonación Molecular , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , Composición Familiar , Concentración de Iones de Hidrógeno , Metano/metabolismo , Datos de Secuencia Molecular , Oxidación-Reducción , Reacción en Cadena de la Polimerasa , ARN Ribosómico 16S/genética , Alineación de Secuencia , Suelo , Microbiología del Suelo , Temperatura
14.
Water Sci Technol ; 59(11): 2253-63, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19494466

RESUMEN

High pH (> 12) leachates are an environmental problem associated with drainage from lime (CaO)-rich industrial residues such as steel slags, lime spoil and coal combustion residues. Recent research has highlighted the potential for natural ('volunteer') wetlands to buffer extremely alkaline influent waters. This appears ascribable to high CO(2) partial pressures in the wetland waters from microbial respiration, which accelerates precipitation of calcium carbonate (CaCO(3)), and the high specific surface area for mineral precipitation offered by macrophytes. The research presented here builds on this and provides preliminary evaluation of a constructed wetland built in March 2008 to buffer drainage from steel slag heaps in north-east England. The drainage water from the slag mounds is characterised by a mean pH of 11.9, high concentrations of Ca (up to 700 mg/L), total alkalinity (up to 800 mg/L as CaCO(3)) and are slightly brackish (Na = 300 mg/L; Cl = 400 mg/L) reflecting native groundwaters at this coastal setting. Documented calcite precipitation rates (mean of 5 g CaCO(3)/m(2)/day) from nearby volunteer sites receiving steel slag drainage were used to scale the constructed wetland planted with Phragmites australis; a species found to spontaneously grow in the vicinity of the discharge. Improved performance of the wetland during summer months may at least in part be due to biological activity which enhances rates of calcite precipitation and thus lowering of pH. Secondary Ca-rich precipitates also serve as a sink for some trace elements present at low concentrations in the slag leachate such as Ni and V. The implications for scaling and applying constructed wetlands for highly alkaline drainage are discussed.


Asunto(s)
Restauración y Remediación Ambiental/métodos , Residuos Industriales , Contaminantes Químicos del Agua/análisis , Contaminación del Agua/prevención & control , Humedales , Inglaterra , Concentración de Iones de Hidrógeno , Acero
15.
Maturitas ; 123: 37-39, 2019 May.
Artículo en Inglés | MEDLINE | ID: mdl-31027675

RESUMEN

UK national guidelines recommend that older people at risk of falling should have their fracture risk assessed and acted upon. People with cognitive impairment are more likely to sustain a fracture than their cognitively intact peers. We assessed the fracture risk of 79 memory clinic attendees and compared their actual management with guidelines. Despite reporting 57 falls in the last year, only 36% of those who would be recommended antiresportive treatment were prescribed it and a dual-energy X-ray absorptiometry (DEXA)scan was performed in only 13% where it would be recommended. These findings highlight an important deficit in fracture risk assessment which should inform future interventions.


Asunto(s)
Accidentes por Caídas/estadística & datos numéricos , Conservadores de la Densidad Ósea/uso terapéutico , Disfunción Cognitiva/complicaciones , Osteoporosis/diagnóstico por imagen , Fracturas Osteoporóticas/prevención & control , Absorciometría de Fotón , Anciano , Anciano de 80 o más Años , Densidad Ósea , Femenino , Fracturas Óseas/prevención & control , Adhesión a Directriz , Humanos , Masculino , Memoria , Osteoporosis/complicaciones , Osteoporosis/tratamiento farmacológico , Guías de Práctica Clínica como Asunto , Medición de Riesgo , Reino Unido
16.
Environ Pollut ; 151(1): 165-75, 2008 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-17400351

RESUMEN

There has been considerable progress in developing treatment systems for point sources of minewater pollution in recent years; however, there remains a knowledge gap in the characterisation and remediation of diffuse minewater sources. Data are presented from the River Gaunless catchment, a historically heavily coal mined catchment in the northeast of England. Instream iron (Fe) loadings were monitored alongside loadings arising from point minewater discharges over a 12-month period to assess the dynamic importance of diffuse sources of minewater pollution. In low flow, diffuse sources account for around 50% of instream loading, a proportion which increases to 98% in high flow conditions. The low flow sources appear to be dominated by direct discharge of contaminated groundwater to surface waters in lower reaches of the catchment. In high flow, resuspended Fe-rich sediments, which are both naturally occurring and derived from historic mining, become the dominant diffuse source of Fe in the water column.


Asunto(s)
Minas de Carbón , Monitoreo del Ambiente/métodos , Contaminación Ambiental/análisis , Residuos Industriales/análisis , Inglaterra , Contaminación Ambiental/efectos adversos , Sedimentos Geológicos/análisis , Hierro/análisis , Ríos , Contaminantes Químicos del Agua/análisis
17.
Sci Total Environ ; 373(2-3): 435-46, 2007 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-17173955

RESUMEN

Mine water pollution is a major cause of surface- and groundwater pollution in former mining districts throughout Europe. It is a potential barrier to achieving good status water bodies, which is a requirement of the EU Water Framework Directive. In the UK, a concerted effort has been made over the last decade or so to address the scientific and practical challenges relating to the remediation of mine water pollution. However, most of this work has focused on remediation of point sources of pollution (typically arising from abandoned mines and shafts), while the behaviour of mine water at the groundwater-surface water interface (the "hyporheic zone") has received far less attention in relevant scientific and engineering literature. The extent of mine water pollution and capacity for its attenuation at the hyporheic zone has not been well quantified while, furthermore, the complex chemical and microbial processes occurring there (specifically with reference to mining-derived pollutants) have not been investigated in any depth. The absence of such data may relate, in a large part, to the difficulty in physically measuring volumes and concentrations associated with these river inputs/exports. A far greater body of literature addresses biogeochemical processes at the hyporheic zone (especially relating to manganese), albeit many such articles relate to aqueous metal dynamics in general, rather than mine water specifically. This paper presents a review of the natural attenuation processes that may limit the movement and availability of mining-derived pollutants at the groundwater-surface water (GW-SW) interface, and specifically within the hyporheic zone. A substantial part focuses on precipitation and adsorption processes at the hyporheic zone, as well as discussing the role of microbial processes in governing metal ion mobility.


Asunto(s)
Agua Dulce/química , Minería/normas , Contaminantes Químicos del Agua/análisis , Abastecimiento de Agua/normas , Adsorción , Biodegradación Ambiental , Precipitación Química , Hierro/análisis , Compuestos de Manganeso/análisis , Oxidación-Reducción , Óxidos/análisis , Reino Unido
18.
Environ Pollut ; 143(2): 261-8, 2006 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16443312

RESUMEN

A permeable reactive barrier (PRB) for remediation of coal spoil heap drainage in Northumberland, UK, is described. The drainage has typical chemical characteristics of pH<4, [acidity]>1400 mg/L as CaCO3, [Fe]>300 mg/L, [Mn]>165 mg/L, [Al]>100mg/L and [SO4]>6500 mg/L. During 2 years of operation the PRB has typically removed 50% of the iron and 40% of the sulphate from this subsurface spoil drainage. Bacterial sulphate reduction appears to be a key process of this remediation. Treatment of the effluent from the PRB results in further attenuation; overall reductions in iron and sulphate concentrations are 95% and 67% respectively, and acidity concentration is reduced by an order of magnitude. The mechanisms of attenuation of these, and other, contaminants in the drainage are discussed. Future research and operational objectives for this novel, low-cost, treatment system are also outlined.


Asunto(s)
Restauración y Remediación Ambiental/métodos , Residuos Industriales , Metales Pesados , Minería , Contaminantes Químicos del Agua , Purificación del Agua/métodos , Bacterias/metabolismo , Biodegradación Ambiental , Inglaterra , Monitoreo del Ambiente/métodos , Concentración de Iones de Hidrógeno , Hierro , Permeabilidad , Lluvia , Sulfatos , Administración de Residuos , Movimientos del Agua
19.
Cancer Res ; 47(21): 5739-47, 1987 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-3664478

RESUMEN

A new in vivo has been developed for evaluating the antitumor activity of chemotherapeutic drugs. The assay is based on a microencapsulation technology developed by Damon Biotech, Inc., Boston, MA, which makes it possible to encapsulate human tumor cells in small (about 1 mm in diameter) microcapsules with semipermeable membranes. Microcapsules containing human tumor cells were injected i.p. into nude or C57BL/6 mice and drugs were administered i.v. The microcapsules were recovered at various intervals following treatment and determinations of drug effects were made based on the differences in the number of tumor cells recovered from the treated and nontreated animals. Using this assay we found that (a) encapsulated tumor cells grew better in the in vivo system than in vitro under the conditions tested; (b) drugs crossed the capsular membrane and killed or inhibited the proliferation of tumor cells; and (c) the antitumor effect was consistent with the relative therapeutic efficacy of drugs or level of resistance of tumor cells detected by other in vitro or in vivo tests. The tumor microencapsulation assay offers several properties which make it attractive for use in new drug development: (a) the antitumor activity of drugs can be tested against human tumor cells under conditions which provide for three-dimensional growth and in vivo supply of nutrients; (b) the sensitivity of tumor cells can be assessed following exposure to drugs at concentrations which are achievable in vivo; (c) compounds requiring in vivo metabolic activation can be tested; (d) the effect of each drug injection can be quickly evaluated; (e) inhibition of tumor cell proliferation versus cytoreductive effects of drugs can be discriminated; (f) the test is applicable to virtually all histological types of human tumor cells; and (g) the tumor microencapsulation assay is a short-term, simple, and relatively inexpensive assay.


Asunto(s)
Ensayos de Selección de Medicamentos Antitumorales/métodos , Células Tumorales Cultivadas/efectos de los fármacos , Animales , Ciclofosfamida/farmacología , Doxorrubicina/farmacología , Femenino , Fluorouracilo/farmacología , Humanos , Linfoma/patología , Ratones , Ratones Endogámicos C57BL , Trasplante de Neoplasias , Ensayo de Capsula Subrrenal , Trasplante Heterólogo
20.
Biochim Biophys Acta ; 626(1): 154-61, 1980 Nov 20.
Artículo en Inglés | MEDLINE | ID: mdl-7459378

RESUMEN

N-terminal amino acid sequence data on cobra venom phospholipase A2 (Naja naja naja) demonstrate the absence of histidine at positions 10 and 20, in contrast to most other Naja enzymes. The presence of three tryptophans was demonstrated by p-toluenesulfonic acid hydrolysis, and the location of two of these at positions 18 and 19 parallels other Naja phospholipase A2 sequences. Based on the amino acid composition of the enzyme, the theoretical E278 0.1% should be 2.2, which is consistent with dry weight determinations, refractometry and amino acid analysis. Unusually high reactivity of the enzyme toward the protein assay of Lowry et al. gives an erroneously low E278 0.1% value of 1.45 when compared to bovine serum serum albumin as a protein standard. Using an E278 0.1% of 2.2, this enzyme is inactivated by the active site reagent p-bromophenacyl bromide with a stoichiometry of 1 mol reagent per mol enzyme. Chromatography on Affi-Gel Blue provides further purification of this phospholipase A2.


Asunto(s)
Venenos Elapídicos , Fosfolipasas A , Fosfolipasas , Acetofenonas , Secuencia de Aminoácidos , Indicadores y Reactivos , Fosfolipasas/aislamiento & purificación , Fosfolipasas A/aislamiento & purificación , Fosfolipasas A2 , Espectrofotometría Ultravioleta , Triptófano/análisis , Tirosina/análisis
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