Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 232
Filtrar
1.
Pain Physician ; 24(S1): S27-S208, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33492918

RESUMO

BACKGROUND: Chronic spinal pain is the most prevalent chronic disease with employment of multiple modes of interventional techniques including epidural interventions. Multiple randomized controlled trials (RCTs), observational studies, systematic reviews, and guidelines have been published. The recent review of the utilization patterns and expenditures show that there has been a decline in utilization of epidural injections with decrease in inflation adjusted costs from 2009 to 2018. The American Society of Interventional Pain Physicians (ASIPP) published guidelines for interventional techniques in 2013, and guidelines for facet joint interventions in 2020. Consequently, these guidelines have been prepared to update previously existing guidelines. OBJECTIVE: To provide evidence-based guidance in performing therapeutic epidural procedures, including caudal, interlaminar in lumbar, cervical, and thoracic spinal regions, transforaminal in lumbar spine, and percutaneous adhesiolysis in the lumbar spine. METHODS: The methodology utilized included the development of objective and key questions with utilization of trustworthy standards. The literature pertaining to all aspects of epidural interventions was viewed with best evidence synthesis of available literature and  recommendations were provided. RESULTS: In preparation of the guidelines, extensive literature review was performed. In addition to review of multiple manuscripts in reference to utilization, expenditures, anatomical and pathophysiological considerations, pharmacological and harmful effects of drugs and procedures, for evidence synthesis we have included 47 systematic reviews and 43 RCTs covering all epidural interventions to meet the objectives.The evidence recommendations are as follows: Disc herniation: Based on relevant, high-quality fluoroscopically guided epidural injections, with or without steroids, and results of previous systematic reviews, the evidence is Level I for caudal epidural injections, lumbar interlaminar epidural injections, lumbar transforaminal epidural injections, and cervical interlaminar epidural injections with strong recommendation for long-term effectiveness.The evidence for percutaneous adhesiolysis in managing disc herniation based on one high-quality, placebo-controlled RCT is Level II with moderate to strong recommendation for long-term improvement in patients nonresponsive to conservative management and fluoroscopically guided epidural injections. For thoracic disc herniation, based on one relevant, high-quality RCT of thoracic epidural with fluoroscopic guidance, with or without steroids, the evidence is Level II with moderate to strong recommendation for long-term effectiveness.Spinal stenosis: The evidence based on one high-quality RCT in each category the evidence is Level III to II for fluoroscopically guided caudal epidural injections with moderate to strong recommendation and Level II for fluoroscopically guided lumbar and cervical interlaminar epidural injections with moderate to strong recommendation for long-term effectiveness.The evidence for lumbar transforaminal epidural injections is Level IV to III with moderate recommendation with fluoroscopically guided lumbar transforaminal epidural injections for long-term improvement. The evidence for percutaneous adhesiolysis in lumbar stenosis based on relevant, moderate to high quality RCTs, observational studies, and systematic reviews is Level II with moderate to strong recommendation for long-term improvement after failure of conservative management and fluoroscopically guided epidural injections. Axial discogenic pain: The evidence for axial discogenic pain without facet joint pain or sacroiliac joint pain in the lumbar and cervical spine with fluoroscopically guided caudal, lumbar and cervical interlaminar epidural injections, based on one relevant high quality RCT in each category is Level II with moderate to strong recommendation for long-term improvement, with or without steroids. Post-surgery syndrome: The evidence for lumbar and cervical post-surgery syndrome based on one relevant, high-quality RCT with fluoroscopic guidance for caudal and cervical interlaminar epidural injections, with or without steroids, is Level II with moderate to strong recommendation for long-term improvement. For percutaneous adhesiolysis, based on multiple moderate to high-quality RCTs and systematic reviews, the evidence is Level I with strong recommendation for long-term improvement after failure of conservative management and fluoroscopically guided epidural injections. LIMITATIONS: The limitations of these guidelines include a continued paucity of high-quality studies for some techniques and various conditions including spinal stenosis, post-surgery syndrome, and discogenic pain. CONCLUSIONS: These epidural intervention guidelines including percutaneous adhesiolysis were prepared with a comprehensive review of the literature with methodologic quality assessment and determination of level of evidence with strength of recommendations.

2.
J Hazard Mater ; 406: 124724, 2020 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-33307445

RESUMO

Bone char catalyzed dechlorination of trichloroethylene (TCE) by green rust (iron(II)-iron(III) hydroxide, GR) has introduced a promising new reaction platform for degradation of chlorinated solvents. This study aimed to reveal whether a broader class of biochars are catalytically active for the dechlorination reaction and to identify which biochar properties are the most important for the catalytic activity. Biochars produced by pyrolysis of animal, plant, and sewage waste substrates at 950 °C were prepared for catalytic dechlorination of TCE by GR tested in batch experiments with 0.15 g L-1 biochar, 3.2 g L-1 GR, and ~ 20 µM TCE. The results showed that the biochar substrate significantly affects its catalytic activity, with the highest TCE reduction rate observed for bone and shrimp-based biochars (k ≥ 0.18 h-1), whereas no reactivity was seen for graphite and activated carbon references. Multivariate regression indicated that the biochar catalytic activity is controlled by multiple biochar properties - biochar surface area, TCE sorption, abundance of C-O groups, and pore size are the properties that impact the catalytic activity most. Derivation of biochar reactivity relationship for a broad spectrum of biochars provides a new approach for identifying proper biochar catalysts for pollutant degradation.

3.
Micromachines (Basel) ; 11(12)2020 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-33339146

RESUMO

Micro polymer parts can be usually manufactured either by conventional injection moulding (IM) or by micro-injection moulding (µIM). In this paper, functional analysis was used as a tool to investigate the performances of IM and µIM used to manufacture the selected industrial component. The methodology decomposed the production cycle phases of the two processes and attributed functions to parts features of the two investigated machines. The output of the analysis was aimed to determine casual chains leading to the final outcome of the process. Experimental validation of the functional analysis was carried out moulding the same micro medical part in thermoplastic elastomer (TPE) material using the two processes by means of multi-cavity moulds. The produced batches were assessed using a precision scale and a high accuracy optical instrument. The measurement results were compared using capability indexes. The data-driven comparison identified and quantified the correlations between machine design and part quality, demonstrating that the µIM machine technology better meets the accuracy and precision requirements typical of micro manufacturing productions.

4.
Sci Rep ; 10(1): 19784, 2020 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-33188248

RESUMO

Pyrrolizidine alkaloids (PAs) are persistent mutagenic and carcinogenic compounds produced by many common plant species. Health authorities recommend minimising human exposure via food and medicinal products to ensure consumer health and safety. However, there is little awareness that PAs can contaminate water resources. Therefore, no regulations exist to limit PAs in drinking water. This study measured a PA base concentration of ~ 70 ng/L in stream water adjacent to an invasive PA-producing plant Petasites hybridus (Asteraceae). After intense rain the PA concentration increased tenfold. In addition, PAs measured up to 230 ng/L in seepage water from groundwater wells. The dominant PAs in both water types corresponded to the most abundant PAs in the plants (senkirkine, senecionine, senecionine N-oxide). The study presents the first discovery of persistent plant toxins in well water and their associated risks. In addition, it for the first time reports monocrotaline and monocrotaline N-oxide in Petasites sp.

5.
J Colloid Interface Sci ; 580: 660-668, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32712472

RESUMO

Layered double hydroxides (LDH) and their magnetic composites have been intensively investigated as recyclable high-capacity phosphate sorbents but with little attention to their stability as function of pH and phosphate concentration. The stability of a Fe3O4@SiO2-Mg3Fe LDH P sorbent as function of pH (5-11) and orthophosphate (Pi) concentration (1-300 mg P/L) was investigated. The composite has high adsorption capacity (approx. 80 mg P/g) at pH 5 but with fast dissolution of the LDH component resulting in formation of ferrihydrite as evidenced by Mössbauer spectroscopy. At pH 7 more than 60% of the LDH dissolves within 60 min, while at alkaline pH, the LDH is more stable but with less than 40% adsorption capacity as compared to pH 5. The high Pi sorption at acid to neutral pH is attributed to Pi bonding to the residual ferrihydrite. Under alkaline conditions Pi is sorbed to LDH at low Pi concentration while magnesium phosphates form at higher Pi concentration evidenced by solid-state 31P MAS NMR, powder X-ray diffraction and chemical analyses. Sorption as function of pH and Pi concentration has been fitted by a Rational 2D function allowing for estimation of Pi sorption and precipitation. In conclusion, the instability of the LDH component limits its application in wastewater treatment from acid to alkaline pH. Future use of magnetic LDH composites requires substantial stabilisation of the LDH component.

6.
Micromachines (Basel) ; 11(4)2020 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-32316656

RESUMO

The formation of blister in the injection moulded parts, especially in the film insert moulded parts, is one of most significant causes of part rejection due to cosmetic requirements or functionality issues. The mechanism and physics of blister formation for molded parts are not well-understood by the state-of-the-art literature. The current paper increases the fundamental understanding of the causes for blister formation. In the experiment, a membrane strip of 5 mm in width was overmoulded with Polypropylene (PP), which formed a disc-shaped part with a diameter of 17.25 mm and a thickness of 500 µm. To investigate the influence of the processing parameters, a full factorial design of experiments (DoE) setup was conducted, including mould temperature (Tm), barrel temperature (Tb), injection speed (Vi) and packing pressure (Pp) as variables. The degree of blistering at the surface was characterized by the areal surface roughness parameters Spk and Smr1, measured with a confocal laser microscope. The measurements were taken on the 10 mm long section of the membrane surface in the centre of the moulded part across the entire width of the film. In addition, the film insert moulding (FIM)-process was simulated and the average shrinkage of the substrate material under the membrane was investigated. Eventually, a method and processing window could be defined that could produce blister-free parts.

7.
Sci Total Environ ; 717: 136969, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32062247

RESUMO

Rare earth elements (REEs) have been increasingly diffused to the environment through mining activities and the extensive use in modern commodities, vehicular activities, coal burning and various environmental and agricultural applications. Studies of REEs in urban environments are limited with no data on REEs in urban runoff. To investigate the concentration and distribution of REEs, a total of 150 runoff samples were collected from trafficked areas, rooftops and residential parking lots in a moderate to densely populated area in Beijing, China. The runoff samples were separated into dissolved and particulate phases and analyzed by ICP-MS. The REEs were mainly (>80%) found in the runoff particulate material. The sum of REEs (ΣREE) total concentrations in urban stormwater runoff samples ranged from 0.16 to 185 µg/l. The observed mean total concentration of ΣREE in the runoff samples were 3-14 folds higher and dissolved fractions 1.5 to 6 times higher than published concentrations for recipients such as sewage channels and rivers. The distribution of REEs in runoff was dominated by light REE. Cluster analysis and Pearson's correlations revealed a strong association between the individual REEs pointing to a similar source. Higher Ce concentrations compared to other REEs indicated strong influence from traffic emission particulates. The La/Sm (5.90-8.05), La/Ce (0.53-0.58) and Ce/Yb (31.0-42.7) ratios pointed to REE sources from traffic emissions and coal burning thus defining an urban fingerprint.

8.
Environ Sci Technol ; 54(6): 3643-3652, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32106669

RESUMO

Biochars function as electron transfer mediators and thus catalyze redox transformations of environmental pollutants. A previous study has shown that bone char (BC) has high catalytic activity for reduction of chlorinated ethylenes using layered Fe(II)-Fe(III) hydroxide (green rust) as reductant. In the present study, we studied the rate of trichloroethylene (TCE) reduction by green rust in the presence of BCs obtained at pyrolysis temperatures (PTs) from 450 to 1050 °C. The reactivity increased with PT, yielding a maximum pseudo-first-order rate constant (k) of 2.0 h-1 in the presence of BC pyrolyzed at 950 °C, while no reaction was seen for BC pyrolyzed at 450 °C. TCE sorption, specific surface area, extent of graphitization, carbon content, and aromaticity of the BCs also increased with PT. The electron-accepting capacity (EAC) of BC peaked at PT of 850 °C, and EAC was linearly correlated with the sum of concentrations of quinoid, quaternary N, and pyridine-N-oxide groups measured by XPS. Moreover, no TCE reduction was seen with graphene nanoparticles and graphitized carbon black, which have high degrees of graphitization but low EAC values. Further analyses showed that TCE reduction rates are well correlated with the EAC and the C/H ratio (proxy of electrical conductivity) of the BCs, strongly indicating that both electron-accepting functional groups and electron-conducting domains are crucial for the BC catalytic reactivity. The present study delineates conditions for designing redox-reactive biochars to be used for remediation of sites contaminated with chlorinated solvents.


Assuntos
Tricloroetileno , Poluentes Químicos da Água , Cloro , Ferro , Oxirredução
9.
Artigo em Inglês | MEDLINE | ID: mdl-31931331

RESUMO

Ptaquiloside (PTA) is an illudane glycoside partly responsible for the carcinogenicity of bracken ferns (Pteridium sp.). The PTA analogues ptesculentoside (PTE) and caudatoside (CAU) have similar biochemical reactivity. However, both compounds are highly under-investigated due to the lack of analytical standards and appropriate methods. This study presents a robust method for preparation of analytical standards of PTE, CAU, PTA, the corresponding hydrolysis products: pterosins G, A and B, and an LC-MS based method for simultaneous quantification of the six compounds in bracken. The chromatographic separation of analytes takes 5 min. The observed linear range of quantification was 20-500 µg/L for PTA and pterosin B, and 10-250 µg/L for the remaining compounds (r > 0.999). The limits of detection were 0.08-0.26 µg/L for PTE, CAU and PTA and 0.01-0.03 µg/L for the pterosins, equivalent to 2.0-6.5 µg/g and 0.25-0.75 µg/g in dry weight, respectively. The method was applied on 18 samples of dried fern leaves from 6 continents. Results demonstrated high variation in concentrations of PTE, CAU and PTA with levels prior to hydrolysis up to 3,900, 2,200 and 2,100 µg/g respectively. This is the first analytical method for simultaneous and direct measurement of all six compounds. Its application demonstrated that bracken ferns contain significant amounts of PTE and CAU relative to PTA.


Assuntos
Cromatografia Líquida/métodos , Glicosídeos , Indanos , Pteridium/química , Sesquiterpenos , Glicosídeos/análise , Glicosídeos/química , Indanos/análise , Indanos/química , Limite de Detecção , Modelos Lineares , Espectrometria de Massas/métodos , Compostos Fitoquímicos/análise , Compostos Fitoquímicos/química , Extratos Vegetais/química , Sesquiterpenos Policíclicos/análise , Sesquiterpenos Policíclicos/química , Reprodutibilidade dos Testes , Sesquiterpenos/análise , Sesquiterpenos/química
10.
Dtsch Med Wochenschr ; 144(23): 1619-1628, 2019 11.
Artigo em Alemão | MEDLINE | ID: mdl-31752034

RESUMO

BACKGROUND: Clinicians are commonly confronted with the differential diagnosis of altered mental status, impaired cognition and altered level of consciousness in hospitalized patients including those admitted to medical, geriatric, emergency, intensive and post-operative care units. Although delirium is the most common acute neuropsychiatric condition in the acute hospital setting this diagnosis is commonly delayed, made too late or missed altogether. DIFFICULTIES AND IMPORTANCE OF TIMELY DIAGNOSIS: The causes of delirious states are manifold. Both, direct damage to the brain tissue as well as encephalopathy as a result of other medical diseases, can be the cause of delirium. Depending on the predisposition delirious syndromes can be provoked by minor medical interventions. Clinical presentation is very variable, but remains largely independent of the triggering mechanisms. Purely catatonic, hypoactive, hyperactive and excitatory types as well as mixed forms can be distinguished.Immediate diagnosis of a delirious syndrome and rapid elucidation of its causes are keys for the implementation of curative therapy. There is a need to act fast because delirious phases are associated with significantly longer hospital stay and increased morbidity as a result of long-term cognitive deficits as well as increased mortality. As negative outcome is closely linked to the duration of a delirious episode, early diagnosis and rapid termination of the delirium constitute a significant positive predictor of outcome. In this respect, delirium represents an emergency, with or without concomitant cerebral or extracerebral symptoms.


Assuntos
Delírio , Idoso , Idoso de 80 Anos ou mais , Disfunção Cognitiva , Transtornos da Consciência , Delírio/diagnóstico , Delírio/etiologia , Delírio/fisiopatologia , Diagnóstico Diferencial , Serviço Hospitalar de Emergência , Hospitalização , Humanos
11.
J Colloid Interface Sci ; 554: 433-443, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31325677

RESUMO

Adsorption onto two-dimensional nanosheet materials offers new possibilities for fast and efficient removal of contaminants from waters. Here, the adsorption of As(V) to a new type of iron oxides - single sheet iron oxide (SSI) - has been studied as a function of time, loading and pH. Adsorption of As(V) onto SSI was very fast compared to other iron oxides, with 80% of total As(V) adsorbed within 10 min. Examination by extended X-ray absorption fine structure analysis showed that As(V) forms a bidentate inner-sphere surface complex with SSI. Arsenic(V) adsorption isotherms and adsorption envelopes were well described using a 1-pK Basic Stern surface complexation model involving protonated (Fe2O2AsO2H-) and unprotonated (Fe2O2AsO2-2) inner-sphere surface complexes. The surface complexation constants for As(V) binding to SSI is similar to constants found for goethite and ferrihydrite. Simulated adsorption isotherms for intermediate As(V) concentrations also demonstrate that SSI is performing equally well as goethite and ferrihydrite based on surface area normalized adsorption capacities. The binding affinities at micromolar to submicromolar As(V) solution concentrations are similar for SSI and ferrihydrite. SSI has interesting potential as a stable, high-affinity sorbent for use in applications where efficient and fast removal is required.

12.
PLoS One ; 14(6): e0218628, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31226154

RESUMO

Ptaquiloside is a natural toxin present in bracken ferns (Pteridium sp.). Cattle ingesting bracken may develop bladder tumours and excrete genotoxins in meat and milk. However, the fate of ptaquiloside in cattle and the link between ptaquiloside and cattle carcinogenesis is unresolved. Here, we present the toxicokinetic profile of ptaquiloside in plasma and urine after intravenous administration of ptaquiloside and after oral administration of bracken. Administered intravenously ptaquiloside, revealed a volume of distribution of 1.3 L kg-1 with a mean residence-time of 4 hours. A large fraction of ptaquiloside was converted to non-toxic pterosin B in the blood stream. Both ptaquiloside and pterosin B were excreted in urine (up to 41% of the dose). Oral administration of ptaquiloside via bracken extract or dried ferns did not result in observations of ptaquiloside in body fluids, indicating deglycosolidation in the rumen. Pterosin B was detected in both plasma and urine after oral administration. Hence, transport of carcinogenic ptaquiloside metabolites over the rumen membrane is indicated. Pterosin B recovered from urine counted for 7% of the dose given intravenously. Heifers exposed to bracken for 7 days (2 mg ptaquiloside kg-1) developed preneoplastic lesions in the urinary bladder most likely caused by genotoxic ptaquiloside metabolites.


Assuntos
Carcinógenos/farmacocinética , Bovinos/metabolismo , Indanos/farmacocinética , Sesquiterpenos/farmacocinética , Animais , Inativação Metabólica , Indanos/sangue , Indanos/urina , Pteridium/química , Rúmen/metabolismo , Sesquiterpenos/sangue , Sesquiterpenos/urina
13.
Environ Sci Process Impacts ; 21(7): 1204-1214, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31241099

RESUMO

Saponins form a group of plant-produced glycosides with potential as biopesticide ingredients. The environmental fate of saponins has never been fully investigated. In the present study, we use QS-18, a specific saponin from Quillaja saponaria as an example, to quantify hydrolysis under different conditions of pH, temperature and water chemical composition. Saponin hydrolysis in buffer solutions was base-catalyzed and followed first-order kinetics. Thus, hydrolysis was slow at pH 5.1 with a half-life of 330 ± 220 d (26 °C), which increases to 0.06 ± 0.01 d at pH 10.0. Hydrolysis rates were highly sensitive to temperature with an activation energy of 56.9 ± 14.2 kJ mol-1 at pH 7.2. In strong contrast, hydrolysis in lake waters (pH 6.4-8.2) produced different patterns with a fast initial dissipation of 25 to 60% of the added saponin within the first five hours, followed by an extremely slow reaction with 25 to 75% unreacted saponin left after reaction times longer than 120 h. The fast dissipation followed by slow hydrolysis in lake water was hypothesized to be attributed to sorption and/or flocculation of saponins by inorganic nanoparticles and/or solutes in the lake water followed by inactivation of hydrolysis due to the sorption/flocculation. The present study demonstrates that saponins may hydrolyze slowly under acidic and cold conditions. In addition, it demonstrates that dissipation kinetics in natural waters may deviate substantially from the kinetics predicted based on laboratory experiments with "clean" buffered solutions. This emphasizes the need for a deeper understanding of the processes affecting the dissipation kinetics of potential toxins under natural conditions, as fate models based on laboratory derived kinetic data may be seriously flawed.


Assuntos
Agentes de Controle Biológico/química , Lagos/química , Quillaja/química , Saponinas/química , Floculação , Concentração de Íons de Hidrogênio , Hidrólise , Cinética , Nanopartículas/química , Soluções , Temperatura
14.
Environ Pollut ; 248: 584-598, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30836240

RESUMO

Metals are among the most toxic pollutants in urban stormwater. To investigate the concentration of dissolved and particulate fractions, the temporal variation during rain events, the effect of wash-off surface, and to assess the pollution status of metals in urban runoff, a total of 155 samples were collected mainly from trafficked areas, roofs and parking lots in Beijing from March to November 2015. Most of the metals were found mainly in the particulate fraction (68-96%) from trafficked surfaces, while for roof runoff Cd, Fe, Mn and Zn were found more equally in dissolved and particulate fractions. Metal concentrations were higher during start of a rain event than later (p < 0.05), and also were higher the longer the period of antecedent dry days. The mean concentration of all metals in trafficked areas exceeded both the Chinese standard Level III (swimming and fishery waters) and the European standards (surface water). Mean concentrations of Cd, Mn, Zn, Al, Fe, Pb and Ni from trafficked areas were 2-10 times higher due to higher traffic intensity and substantial atmospheric deposition, while Sb was 20 times higher than in any other reported data for urban runoff. Cluster analysis (CA) and principal component analysis (PCA) together with Pearson's correlation co-efficient suggested that Cd, Cr, Cu, Mn, Ni, Pb, and Zn mainly originates from vehicular activities, while Mn and Zn in roof runoff is due to atmospheric deposition. The geo-accumulation and pollution indices show that runoff from trafficked areas are moderately to heavily polluted by most metals, except Cu and Zn. Thus, Beijing urban runoff presents an environmental risk towards lakes, bathing water and drinking water. The results can be used as basis for development of stormwater and pollution control strategies.


Assuntos
Monitoramento Ambiental/métodos , Metais Pesados/análise , Material Particulado/análise , Chuva/química , Poluentes Químicos da Água/análise , Pequim , Urbanização
15.
Sci Total Environ ; 665: 617-619, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30776633

RESUMO

Illegal wolf kills happens around in Europe despite the European wolf is protected under the EU Habitats Directive. The reason for this is conflicts with farmers and local hunters and in some instances also direct fear. In April 2018, a wolf was killed in Denmark after 1st recolonization since the 18th century. This caused a heated debate and calls for better communication and management of the Danish and entire European wolf population. Here we discuss the challenges of illegal wolf kills and call for European governments to take action. We specifically encourage European governments to create facilitated spaces for public deliberation on wildlife management by integrating facts and values, not separating them.


Assuntos
Conservação dos Recursos Naturais , Disseminação de Informação , Lobos , Animais , Dinamarca , União Europeia , Densidade Demográfica , Mídias Sociais/estatística & dados numéricos
16.
Chemosphere ; 223: 723-730, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30802838

RESUMO

Globally, more than 30% of soils are poor in phosphorus (P) and the productivity of these soils is severely restricted without the addition of P fertiliser. With future P supplies becoming limited, it is becoming increasingly important to identify ways of optimising the use of waste materials as P fertilisers. One technology that has been promoted extensively in recent years to improve quality of degraded soils is the application of biochar. In this context, char produced from recycled animal bone is of special interest because of its high P content (∼15%). This study investigated how production temperature affects chemical P forms in bone char and the impact on soil P availability in different P-deficient soils. The major P form in dried bone meal was poorly crystalline hydroxyapatite. As the pyrolysis temperature increased to 1050 °C, the hydroxyapatite structure measured with X-ray absorption near edge structure (XANES) spectroscopy persisted. Furthermore, crystallinity increased at temperatures above 750 °C, as revealed by X-ray powder diffraction (XRD). Plant availability was highest for bone char produced between 300 °C and 500 °C in three acidic soils from three continents, and declined rapidly above 750 °C. This strongly indicated that crystallinity of hydroxyapatite limits plant availability at high pyrolysis temperatures. In a high pH soil, all materials resulted in low P availability. As pyrolysis increased the P availability in comparison with dried bone, it was concluded that bone char produced at temperatures between 300 °C and 500 °C has the potential to improve fertility of P-poor, low pH soils.


Assuntos
Apatitas , Carvão Vegetal/farmacologia , Fósforo , Solo/química , Animais , Osso e Ossos/química , Carvão Vegetal/química , Fertilizantes , Temperatura
17.
Pest Manag Sci ; 75(4): 1150-1158, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30324681

RESUMO

BACKGROUND: Field experiments were carried out in 2016 and 2017 to study the influence of timing the application of nitrogen fertilizer (N-fertilizer) on the susceptibility of potatoes to early blight. We hypothesized that potatoes that receive N-fertilizer as split applications or a one-time application at emergence will have a higher N content and be less susceptible to early blight than those that receive N-fertilizer as a one-time application before planting. N-fertilizer was applied either as a one-time application before planting or at emergence and as split applications. RESULTS: Potatoes that did not receive N-fertilizer were more susceptible to early blight [high area under the disease progress curve (AUDPC)] than those that did receive N-fertilizer (low AUDPC). The timing of N-fertilizer application had a significant effect on the susceptibility of potatoes to early blight. Potatoes that received the entire quantity of N-fertilizer at emergence or as split applications had higher N contents and were less susceptible to early blight than those that received the entire quantity of N-fertilizer before planting. Potatoes that did not receive N-fertilizer had a markedly lower starch yield than potatoes that received N-fertilizer. Potatoes that received the entire quantity of N-fertilizer before planting had a lower starch yield than potatoes that received the entire quantity of N-fertilizer at emergence or as split applications. CONCLUSION: N-fertilizer applied as a one-time application at emergence or as a split application was the best treatment to ensure both high N content and lower attack of early blight, which confirms our hypothesis. © 2018 Society of Chemical Industry.


Assuntos
Alternaria/fisiologia , Produção Agrícola/métodos , Fertilizantes/análise , Nitrogênio/administração & dosagem , Doenças das Plantas/microbiologia , Solanum tuberosum/efeitos dos fármacos , Dinamarca , Solanum tuberosum/microbiologia
18.
J Hazard Mater ; 364: 39-47, 2019 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-30336334

RESUMO

In order to overcome the inefficiency of heterogeneous electro-Fenton process for water treatment at neutral pH, single sheet iron oxide (SSI) derived from layered Fe(II)-Fe(III) double hydroxides (green rusts) was fabricated on an indium tin oxide electrode via layer by layer assembly and used in an undivided electrolysis cell. Use of radical scavengers demonstrated the formation of oxygen radicals by electrochemical reduction of oxygen at the SSI electrode, and the key role of hydroxyl radicals (OH) and superoxide anion (O2-) radicals in degradation of the azo dye orange II. Analysis of degradation products by UV-vis, LC-MS and GC-MS further demonstrated that direct reduction toke place in addition to indirect oxidation. The reactivity of SSI as a heterogeneous electro-Fenton catalyst is two order of magnitude higher than its homogenous counterparts. The SSI electrode was highly stable as the dye degradation did not decrease after use for 19 h with no Fe leaching. The high dye removal efficiency was maintained in a wide pH range from 7 to 10 and in different supporting electrolytes, demonstrating the application of this process under various conditions mimicking natural waters.

19.
Ambio ; 48(3): 230-239, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29956076

RESUMO

Self-policing is essential for addressing wildlife-related crime where illegal activity is extremely diffuse, and limited resources are available for monitoring and enforcement. Emerging research on self-policing suggest key drivers including economics, folk traditions, and socio-political resistance. We build on this research with a case study evaluating potential drivers of self-policing illegal wolf killing among Swedish hunting teams. Swedish hunters marginally leaned toward considering illegal hunting of wolves an expression of resistance (10.30 out of a possible 17 on a resistance scale) and strongly believed outsiders had undue influence over hunting (15.79 out of a possible 21 on an influence scale). Most (73%) Swedish hunters stated they would report illegal wolf killing to authorities, but 20% stated they would handle the infractions through internal sanctions. Viewing illegal hunting of wolves as a form of political resistance, viewing wolf management as being controlled locally, and perceived prevalence of illegal wolf killing among hunting acquaintances were positive predictors of preferring internal sanctions to address illegal wolf killing over reporting the crimes. Resistance and perceived prevalence of wolf killing also predicted preferring no action to address illegal wolf killing. These results suggest that a counterpublic of marginalized ruralism may promote forms of self-policing that rely on internal censure for illegal wolf killing rather than using formal legal channels. Similarly, folk traditions within this counterpublic (e.g., perceptions of prevalence of illegal wolf killing) shape if and how internal sanctions are advocated. Re-engaging marginalized hunting groups and emphasizing the rarity of illegal wolf killing may promote wolf conservation, both in Sweden and in other democratic regimes.


Assuntos
Lobos , Animais , Animais Selvagens , Conservação dos Recursos Naturais , Crime , Suécia
20.
Micromachines (Basel) ; 9(2)2018 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-30393334

RESUMO

This paper reports an investigation of the effects of process parameters on the quality characteristics of polymeric parts produced by micro injection moulding (µIM) with two different materials. Four injection moulding process parameters (injection velocity, holding pressure, melt temperature and mould temperature) were investigated using Polypropylene (PP) and Acrylonitrile Butadiene Styrene (ABS). Three key characteristics of the mouldings were evaluated with respect to process settings and the material employed: part mass, flow length and flash formation. The experimentation employs a test part with four micro fingers with different aspect ratios (from 21 up to 150) and was carried out according to the Design of Experiments (DOE) statistical technique. The results show that holding pressure and injection velocity are the most influential parameters on part mass with a direct effect for both materials. Both parameters have a similar effect on flow length for both PP and ABS at all aspect ratios and have higher effects as the feature thickness decreased below 300 µm. The study shows that for the investigated materials the injection speed and packing pressure were the most influential parameters for increasing the amount of flash formation, with relative effects consistent for both materials. Higher melt and mould temperatures settings were less influential parameters for increasing the flash amount when moulding with both materials. Of the two investigated materials, PP was the one exhibiting more flash formation as compared with ABS, when corresponding injection moulding parameters settings for both materials were considered.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...