RESUMEN
Mercury (Hg2+) and silver (Ag+) ions possess the harmful effects on public health and environment that makes it essential to develop the sensing techniques with great sensitivity for the ions. Metal ions commonly coexist in the different biological and environmental systems. Hence, it is an urgent demand to design a simple method for the simultaneous detection of metal ions, peculiarly in the case of coexisting Hg2+ and Ag+. This study introduces a low-cost paper-based aptasensor to monitor Hg2+ and Ag+, simultaneously. The strategy of the sensing array is according to the conformational changes of Hg2+- and Ag+-specific aptamers and their release from the GO surface after the injection of the target sample on the sensing platform. Through monitoring the fluorescence recovery changes against the concentrations of the ions, Hg2+ and Ag+ can be determined as low as 1.33 and 1.01 pM. The paper-based aptasensor can simultaneously detect the ions within about 10 min. The aptasensor is applied prosperously to monitor Hg2+ and Ag+ in human serum, water, and milk. The designed aptasensor with the main advantages of simplicity and feasibility holds the supreme potential to develop a cost-effective sensing method for environmental monitoring, food control, and human diagnostics.
Asunto(s)
Aptámeros de Nucleótidos/química , Técnicas Biosensibles , Mercurio/análisis , Papel , Plata/análisis , Aptámeros de Nucleótidos/economía , Técnicas Biosensibles/economía , Grafito/química , Grafito/economía , Mercurio/economía , Plata/economíaRESUMEN
BACKGROUND: Insertion of a ventriculoperitoneal shunt for hydrocephalus is one of the commonest neurosurgical procedures worldwide. Infection of the implanted shunt affects up to 15% of these patients, resulting in prolonged hospital treatment, multiple surgeries, and reduced cognition and quality of life. Our aim was to determine the clinical and cost-effectiveness of antibiotic (rifampicin and clindamycin) or silver shunts compared with standard shunts at reducing infection. METHODS: In this parallel, multicentre, single-blind, randomised controlled trial, we included patients with hydrocephalus of any aetiology undergoing insertion of their first ventriculoperitoneal shunt irrespective of age at 21 regional adult and paediatric neurosurgery centres in the UK and Ireland. Patients were randomly assigned (1:1:1 in random permuted blocks of three or six) to receive standard shunts (standard shunt group), antibiotic-impregnated (0·15% clindamycin and 0·054% rifampicin; antibiotic shunt group), or silver-impregnated shunts (silver shunt group) through a randomisation sequence generated by an independent statistician. All patients and investigators who recorded and analysed the data were masked for group assignment, which was only disclosed to the neurosurgical staff at the time of operation. Participants receiving a shunt without evidence of infection at the time of insertion were followed up for at least 6 months and a maximum of 2 years. The primary outcome was time to shunt failure due the infection and was analysed with Fine and Gray survival regression models for competing risk by intention to treat. This trial is registered with ISRCTN 49474281. FINDINGS: Between June 26, 2013, and Oct 9, 2017, we assessed 3505 patients, of whom 1605 aged up to 91 years were randomly assigned to receive either a standard shunt (n=536), an antibiotic-impregnated shunt (n=538), or a silver shunt (n=531). 1594 had a shunt inserted without evidence of infection at the time of insertion (533 in the standard shunt group, 535 in the antibiotic shunt group, and 526 in the silver shunt group) and were followed up for a median of 22 months (IQR 10-24; 53 withdrew from follow-up). 32 (6%) of 533 evaluable patients in the standard shunt group had a shunt revision for infection, compared with 12 (2%) of 535 evaluable patients in the antibiotic shunt group (cause-specific hazard ratio [csHR] 0·38, 97·5% CI 0·18-0·80, p=0·0038) and 31 (6%) of 526 patients in the silver shunt group (0·99, 0·56-1·74, p=0·96). 135 (25%) patients in the standard shunt group, 127 (23%) in the antibiotic shunt group, and 134 (36%) in the silver shunt group had adverse events, which were not life-threatening and were mostly related to valve or catheter function. INTERPRETATION: The BASICS trial provides evidence to support the adoption of antibiotic shunts in UK patients who are having their first ventriculoperitoneal shunt insertion. This practice will benefit patients of all ages by reducing the risk and harm of shunt infection. FUNDING: UK National Institute for Health Research Health Technology Assessment programme.
Asunto(s)
Infecciones Relacionadas con Catéteres/prevención & control , Stents Liberadores de Fármacos/economía , Derivación Ventriculoperitoneal/economía , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Antibacterianos/administración & dosificación , Infecciones Relacionadas con Catéteres/sangre , Infecciones Relacionadas con Catéteres/líquido cefalorraquídeo , Niño , Preescolar , Análisis Costo-Beneficio , Stents Liberadores de Fármacos/efectos adversos , Femenino , Humanos , Hidrocefalia/cirugía , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Plata/economía , Método Simple Ciego , Derivación Ventriculoperitoneal/efectos adversos , Adulto JovenRESUMEN
The goal of this paper is to identify, for the first time, the role of solar production in driving silver prices. The empirical analysis makes use of the ARDL model and the combined cointegration. The results, spanning the period 1990-2016, document that stronger solar installed capacities, as well as higher gross electricity production from solar sources, lead to higher silver prices. The findings could be of great importance to silver suppliers and to energy policymakers and regulators, as well as to solar panel manufacturers.
Asunto(s)
Plata/economía , Energía Solar , ElectricidadRESUMEN
This paper examines the stylized facts, correlation and interaction between volatility and returns at the 5-minute frequency for gold, silver, platinum and palladium from May 2000 to April 2015. We study the full sample period, as well as three subsamples to determine how high-frequency data of precious metals have developed over time. We find that over the full sample, the number of trades has increased substantially over time for each precious metal, while the bid-ask spread has narrowed over time, indicating an increase in liquidity and price efficiency. We also find strong evidence of periodicity in returns, volatility, volume and bid-ask spread. Returns and volume both experience strong intraday periodicity linked to the opening and closing of major markets around the world while the bid-ask spread is at its lowest when European markets are open. We also show a bilateral Granger causality between returns and volatility of each precious metal, which holds for the vast majority subsamples.
Asunto(s)
Metales Pesados/economía , Oro/economía , Humanos , Paladio/economía , Platino (Metal)/economía , Análisis de Regresión , Plata/economía , Factores de TiempoRESUMEN
Locally manufactured ceramic water filters are one effective household drinking water treatment technology. During manufacturing, silver nanoparticles or silver nitrate are applied to prevent microbiological growth within the filter and increase bacterial removal efficacy. Currently, there is no recommendation for manufacturers to test silver concentrations of application solutions or filtered water. We identified six commercially available silver test strips, kits, and meters, and evaluated them by: (1) measuring in quintuplicate six samples from 100 to 1,000 mg/L (application range) and six samples from 0.0 to 1.0 mg/L (effluent range) of silver nanoparticles and silver nitrate to determine accuracy and precision; (2) conducting volunteer testing to assess ease-of-use; and (3) comparing costs. We found no method accurately detected silver nanoparticles, and accuracy ranged from 4 to 91% measurement error for silver nitrate samples. Most methods were precise, but only one method could test both application and effluent concentration ranges of silver nitrate. Volunteers considered test strip methods easiest. The cost for 100 tests ranged from 36 to 1,600 USD. We found no currently available method accurately and precisely measured both silver types at reasonable cost and ease-of-use, thus these methods are not recommended to manufacturers. We recommend development of field-appropriate methods that accurately and precisely measure silver nanoparticle and silver nitrate concentrations.
Asunto(s)
Cerámica/análisis , Filtración/métodos , Plata/química , Purificación del Agua/métodos , Cerámica/economía , Costos y Análisis de Costo , Filtración/economía , Filtración/instrumentación , Plata/economía , Purificación del Agua/economía , Purificación del Agua/instrumentaciónRESUMEN
The physicochemical and biological properties of metals change as the particles are reduced to nanoscale. This ability increases the application of nanoparticles in commercial and medical industry. Keeping in view this importance, Silver nanoparticles (Ag-NPs) were synthesized by reduction methods using formaldehyde as reducing agent in the chemical route and lemon extracts in the biological route. The scanning electron microscope (SEM) images of nanoparticles suggested that the particles were either agglomerated or spherical in shape with mean diameter of 16.59 nm in the chemical route and 42.93 nm in the biological route. The particles were between 5 and 80 nm with maximum frequency between 5 and 20 nm in the chemical route and between 5 and 100 nm with maximum frequency between 15 and 50 nm in the biological method. In the second phase of the study, the effect of Ag-NPs on the oxidative stress was studied. For this purpose, Labeo rohita (20 ± 2.5 g in weight and 12 ± 1.4 cm in length) were involved. Six treatments were applied in three replicates having five fishes in each replicate. The first treatment was used as control group, and the other five treatments were exposed to either 10 or 20 or 30 or 45 or 55 mg L-1 of Ag-NPs for 28 days. The treatment of Ag-NPs caused oxidative stress in the liver and gill tissues, which induced alterations in the activities of antioxidant enzymes. The level of catalase (CAT) was decreased in response to Ag-NPs concentration in dose-dependent manner. Ag-NPs treatment stimulated the liver and gill tissues to significantly increase the level of superoxide dismutase (SOD), which might be due to synthesis of SOD and addition in the pre-existing SOD level. The level decreases again due to depletion of SOD level. There was a sharp decline in the activities of glutathione S-transferase (GST) in both gills and liver tissues even at lower concentration, and this decrease in the GST activity was significantly different at each treatment after 28 days of treatment except 20 mg L-1. The malondialdehyde (MDA) levels of gills and liver tissues were increased with the increase in the concentration. The elevated levels of glutathione (GSH) showed that the liver started defensive mechanism against the oxyradicals. This study finds out the cheap eco-friendly and economical method of Ag-NP synthesis. It is further revealed that Ag-NPs caused oxidative stress in the aquatic animals if exposure occurs at high concentrations.
Asunto(s)
Cyprinidae/metabolismo , Nanopartículas del Metal/economía , Nanopartículas del Metal/toxicidad , Estrés Oxidativo/efectos de los fármacos , Plata/economía , Plata/toxicidad , Animales , Relación Dosis-Respuesta a Droga , Formaldehído/química , Branquias/química , Branquias/efectos de los fármacos , Glutatión/análisis , Hígado/química , Hígado/efectos de los fármacos , Malondialdehído/análisis , Nanopartículas del Metal/química , Tamaño de la Partícula , Plata/química , Propiedades de SuperficieRESUMEN
AIM: To estimate the cost-effectiveness of silver dressings using a health economic model based on time-to-wound-healing in hard-to-heal chronic venous leg ulcers (VLUs). BACKGROUND: Chronic venous ulceration affects 1-3% of the adult population and typically has a protracted course of healing, resulting in considerable costs to the healthcare system. The pathogenesis of VLUs includes excessive and prolonged inflammation which is often related to critical colonisation and early infection. The use of silver dressings to control this bioburden and improve wound healing rates remains controversial. METHODS: A decision tree was constructed to evaluate the cost-effectiveness of treatment with silver compared with non-silver dressings for four weeks in a primary care setting. The outcomes: 'Healed ulcer', 'Healing ulcer' or 'No improvement' were developed, reflecting the relative reduction in ulcer area from baseline to four weeks of treatment. A data set from a recent meta-analysis, based on four RCTs, was applied to the model. RESULTS: Treatment with silver dressings for an initial four weeks was found to give a total cost saving (£141.57) compared with treatment with non-silver dressings. In addition, patients treated with silver dressings had a faster wound closure compared with those who had been treated with non-silver dressings. CONCLUSION: The use of silver dressings improves healing time and can lead to overall cost savings. These results can be used to guide healthcare decision makers in evaluating the economic aspects of treatment with silver dressings in hard-to-heal chronic VLUs.
Asunto(s)
Vendajes/economía , Úlcera de la Pierna/tratamiento farmacológico , Úlcera de la Pierna/economía , Plata/economía , Plata/uso terapéutico , Úlcera Varicosa/tratamiento farmacológico , Úlcera Varicosa/economía , Cicatrización de Heridas/efectos de los fármacos , Adulto , Enfermedad Crónica , Análisis Costo-Beneficio , Humanos , Modelos Económicos , Ensayos Clínicos Controlados Aleatorios como Asunto , Plata/farmacología , Resultado del TratamientoRESUMEN
BACKGROUND: Insertion of a ventriculoperitoneal shunt (VPS) for the treatment of hydrocephalus is one of the most common neurosurgical procedures in the UK, but failures caused by infection occur in approximately 8% of primary cases. VPS infection is associated with considerable morbidity and mortality and its management results in substantial cost to the health service. Antibiotic-impregnated (rifampicin and clindamycin) and silver-impregnated VPS have been developed to reduce infection rates. Whilst there is some evidence showing that such devices may lead to a reduction in VPS infection, there are no randomised controlled trials (RCTs) to support their routine use. METHODS/DESIGN: Overall, 1,200 patients will be recruited from 17 regional neurosurgical units in the UK and Ireland. Patients of any age undergoing insertion of their first VPS are eligible. Patients with previous indwelling VPS, active and on-going cerebrospinal fluid (CSF) or peritoneal infection, multiloculated hydrocephalus requiring multiple VPS or neuroendoscopy, and ventriculoatrial or ventriculopleural shunt planned will be excluded. Patients will be randomised 1:1:1 to either standard silicone (comparator), antibiotic-impregnated, or silver-impregnated VPS. The primary outcome measure is time to VPS infection. Secondary outcome measures include time to VPS failure of any cause, reason for VPS failure (infection, mechanical failure, or patient failure), types of bacterial VPS infection (organism type and antibiotic resistance), and incremental cost per VPS failure averted. DISCUSSION: The British antibiotic and silver-impregnated catheters for ventriculoperitoneal shunts multi-centre randomised controlled trial (the BASICS trial) is the first multi-centre RCT designed to determine whether antibiotic or silver-impregnated VPS reduce early shunt infection compared to standard silicone VPS. The results of this study will be used to inform current neurosurgical practice and may potentially benefit patients undergoing shunt surgery in the future. TRIAL REGISTRATION: International Standard Randomised Controlled Trial Number: ISRCTN49474281.
Asunto(s)
Antibacterianos/administración & dosificación , Infecciones Relacionadas con Catéteres/prevención & control , Catéteres/efectos adversos , Materiales Biocompatibles Revestidos , Hidrocefalia/cirugía , Plata , Derivación Ventriculoperitoneal/efectos adversos , Derivación Ventriculoperitoneal/instrumentación , Antibacterianos/economía , Infecciones Relacionadas con Catéteres/diagnóstico , Infecciones Relacionadas con Catéteres/economía , Infecciones Relacionadas con Catéteres/microbiología , Catéteres/economía , Materiales Biocompatibles Revestidos/economía , Ahorro de Costo , Análisis Costo-Beneficio , Farmacorresistencia Bacteriana , Diseño de Equipo , Falla de Equipo , Costos de la Atención en Salud , Humanos , Hidrocefalia/economía , Plata/economía , Factores de Tiempo , Resultado del Tratamiento , Reino Unido , Derivación Ventriculoperitoneal/economíaRESUMEN
An easy and inexpensive detection method for DNA hybridization assays combining magnetic beads and enzymatically generated silver nanoparticles is introduced. The main advantage of this approach is the possibility to distinguish between positive and negative test results with the naked eye. In the case of complementary DNA sequences the sample will turn black within a few minutes, allowing readout without any hardware. In order to illustrate the applicability of the assay genomic DNA isolated from E. coli contaminated Ringer's solution was used for testing the sensitivity as well as specificity.
Asunto(s)
ADN Bacteriano/aislamiento & purificación , Escherichia coli/aislamiento & purificación , Soluciones Isotónicas/análisis , Nanopartículas del Metal/química , Plata/química , Sondas de ADN/análisis , Sondas de ADN/economía , Sondas de ADN/genética , ADN Bacteriano/genética , Escherichia coli/genética , Nanopartículas del Metal/economía , Reacción en Cadena de la Polimerasa/economía , Reacción en Cadena de la Polimerasa/métodos , Solución de Ringer , Plata/economíaRESUMEN
One of the main obsessions of the early modern era was that of determining the notions of true and false, in order to apply them to various fields of knowledge and thus establish the divide between the lawful and unlawful. This trend was to have a particular impact on the fields of religion and science, where it became necessary to distinguish not only between true and false spirits, relics or miracles, but also between genuine and fake astrologers and alchemists. Situated in the middle ground between idealism and materialism, alchemy was prime territory for such tensions, as was demonstrated by a trial held in 1593 at the Jeronymite monastery of Santa Enracia in Saragossa, whose prior accused a friar of making "silver out of smoke and jewels from goblins".
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Alquimia , Fraude , Religión y Ciencia , Espiritualismo , Folclore , Fraude/economía , Fraude/etnología , Fraude/historia , Fraude/legislación & jurisprudencia , Fraude/psicología , Historia del Siglo XVI , Plata/economía , Plata/historia , España/etnología , Espiritualismo/historia , Espiritualismo/psicologíaAsunto(s)
Vendajes/economía , Costos de Hospital , Departamento de Compras en Hospital/economía , Plata/economía , Infección de Heridas/prevención & control , Antiinfecciosos/economía , Antiinfecciosos/farmacología , Recolección de Datos , Humanos , Departamento de Compras en Hospital/tendencias , Plata/farmacologíaRESUMEN
This prospective, randomized study compared protocols of care using either AQUACEL Ag Hydrofiber (ConvaTec, a Bristol-Myers Squibb company, Skillman, NJ) dressing with silver (n = 42) or silver sulfadiazine (n = 42) for up to 21 days in the management of partial-thickness burns covering 5% to 40% body surface area (BSA). AQUACEL Ag dressing was associated with less pain and anxiety during dressing changes, less burning and stinging during wear, fewer dressing changes, less nursing time, and fewer procedural medications. Silver sulfadiazine was associated with greater flexibility and ease of movement. Adverse events, including infection, were comparable between treatment groups. The AQUACEL Ag dressing protocol tended to have lower total treatment costs (Dollars 1040 vs. Dollars 1180) and a greater rate of re-epithelialization (73.8% vs 60.0%), resulting in cost-effectiveness per burn healed of Dollars 1,409.06 for AQUACEL Ag dressing and Dollars 1,967.95 for silver sulfadiazine. A protocol of care with AQUACEL(R) Ag provided clinical and economic benefits compared with silver sulfadiazine in patients with partial-thickness burns.
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Antiinfecciosos Locales/uso terapéutico , Quemaduras/tratamiento farmacológico , Carboximetilcelulosa de Sodio/uso terapéutico , Apósitos Oclusivos/economía , Sulfadiazina de Plata/uso terapéutico , Plata/uso terapéutico , Adulto , Anciano de 80 o más Años , Antiinfecciosos Locales/efectos adversos , Antiinfecciosos Locales/economía , Carboximetilcelulosa de Sodio/efectos adversos , Carboximetilcelulosa de Sodio/economía , Preescolar , Cicatriz/prevención & control , Análisis Costo-Beneficio , Epitelio/crecimiento & desarrollo , Costos de la Atención en Salud/estadística & datos numéricos , Humanos , Lactante , Masculino , Apósitos Oclusivos/efectos adversos , Evaluación de Resultado en la Atención de Salud , Dimensión del Dolor , Pediatría , Estudios Prospectivos , Plata/efectos adversos , Plata/economía , Sulfadiazina de Plata/efectos adversos , Sulfadiazina de Plata/economíaAsunto(s)
Antiinfecciosos Locales/economía , Vendajes/economía , Medicare Part B/economía , Sistema de Pago Prospectivo/economía , Compuestos de Plata/economía , Carboximetilcelulosa de Sodio/economía , Equipo Médico Durable/economía , Guías como Asunto , Healthcare Common Procedure Coding System/economía , Humanos , Poliésteres/economía , Polietilenos/economía , Plata/economía , Cuidados de la Piel/economía , Cuidados de la Piel/instrumentación , Estados UnidosAsunto(s)
Antiinfecciosos/uso terapéutico , Infección Hospitalaria/prevención & control , Plata/uso terapéutico , Cateterismo Urinario/instrumentación , Antiinfecciosos/economía , Análisis Costo-Beneficio , Infección Hospitalaria/economía , Farmacorresistencia Bacteriana , Humanos , Hidrogeles , Plata/economía , Cateterismo Urinario/economíaRESUMEN
The aim of this analysis was to examine the cost-effectiveness of Contreet Foam (A) in comparison with three other commonly used venous leg ulcer treatment protocols: Aquacel Ag (B), Actisorb Silver (C) and Iodoflex (D). A health-economic analysis reflecting the UK treatment practice and cost structure was performed. The analysis was set up to assess the cost of relative wound area reduction over a 4-week treatment period. The model was validated by a UK expert panel consisting of four wound care specialists. To assure that the 4-week model had a realistic link to cost-effectiveness of complete wound healing, a Markov analysis was also performed. Sensitivity analyses were carried out to ensure validity. Protocol A and C proved to be the most effective treatments. The mean relative reduction in wound area after 4 weeks of treatment was 50.2% (protocol A), 23.9% (protocol B), 44.6% (protocol C) and 36.0% (protocol D). Cost-effectiveness ratios showed that protocol A proved to be the most cost-effective treatment, and protocol B the least. The cost per percentage reduction in wound area was 9.50 UK pounds for protocol A, compared to 16.50-17.60 UK pounds for the other treatment options. The cost-effectiveness of complete healing (Markov analysis) and sensitivity analyses confirmed these results. Using Contreet Foam instead of the other dressing alternatives may imply savings of 2.2-4.4 million UK pounds per year to the National Health Service.
Asunto(s)
Amoxicilina/administración & dosificación , Antibacterianos/administración & dosificación , Costos Directos de Servicios , Apósitos Oclusivos/economía , Plata/administración & dosificación , Úlcera Varicosa/terapia , Amoxicilina/economía , Antibacterianos/economía , Análisis Costo-Beneficio , Humanos , Plata/economía , Factores de Tiempo , Resultado del Tratamiento , Cicatrización de HeridasRESUMEN
Prevalence studies generally find nosocomial urinary tract infections to be the most common type of nosocomial infection, accounting for between 21% and 45% of all HAIs. The main risk factor appears to be the presence of a urinary catheter, with an estimated 80% of these infections being associated with their use. This paper describes a model which quantifies the extent of the burden of these infections in terms of the number of patients affected and the costs incurred by the hospital sector; and identifies the potential benefits of the routine use of silver alloy coated catheters, as a means of reducing the incidence of this type of infection. An illustrative model of the annual costs and benefits associated with the routine use of this intervention in adult, non-day case patients admitted to the medical and surgical specialties of NHS hospitals throughout England is presented. The results suggest that a 14.6% reduction in the incidence of urinary tract infections in catheterized medical patients, and a 11.4% reduction in catheterized surgical patients, would cover the cost of the intervention. Any further reduction in incidence would result in net positive benefits.