Divalent metal nanoparticles     

Devries GA  Brunnbauer M  Hu Y  Jackson AM  Long B  Neltner BT  Uzun O  Wunsch BH  Stellacci F 《Science (New York, N.Y.)》2007,315(5810):358-361

Nanoparticles can be used as the building blocks for materials such as supracrystals or ionic liquids. However, they lack the ability to bond along specific directions as atoms and molecules do. We report a simple method to place target molecules specifically at two diametrically opposed positions in the molecular coating of metal nanoparticles. The approach is based on the functionalization of the polar singularities that must form when a curved surface is coated with ordered monolayers, such as a phase-separated mixture of ligands. The molecules placed at these polar defects have been used as chemical handles to form nanoparticle chains that in turn can generate self-standing films.  相似文献   

The use of external within-person variance estimates to adjust nutrient intake distributions over time and across populations     

Jahns L  Arab L  Carriquiry A  Popkin BM 《Public health nutrition》2005,8(1):69-76

OBJECTIVE: To examine the utility of using external estimates of within-person variation to adjust usual nutrient intake distributions. DESIGN: Analyses of the prevalence of inadequate intake of an example nutrient by the Estimated Average Requirement (EAR) cut-point method using three different methods of statistical adjustment of the usual intake distribution of a single 24-hour recall in Russian children in 1996, using the Iowa State University method for adjustment of the distribution. First, adjusting the usual intake distribution with day 2 recalls from the same 1996 sample (the correct method); second, adjusting the distribution using external variance estimates derived from US children in 1996; and third, adjusting the distribution using external estimates derived from Russian children of the same age in 2000. We also present prevalence estimates based on naive statistical analysis of the unadjusted distribution of intakes. SETTING/SUBJECTS: Children drawn from the Russia Longitudinal Monitoring Survey in 1996 and 2000 and from the 1996 Continuing Survey of Food Intakes by Individuals. RESULTS: When the EAR cut-point method is applied to a single recall, the resulting prevalence estimate in this study is inflated by 100-1300%. When the intake distribution is adjusted using an external variance estimate, the prevalence estimate is much less biased, suggesting that any adjustment may give less biased estimates than no adjustment. CONCLUSIONS: In moderately large samples, adjusting distributions with external estimates of variances results in more reliable prevalence estimates than using 1-day data.  相似文献   

Studies on the Persistence of a Commercial Formulation of Chlorpyrifos on an Agricultural Soil from Provincia de Buenos Aires,República Argentina     

Álvarez  Melina  du Mortier  Cecile  Sokolic  Tea  Cirelli  Alicia Fernández 《Water, air, and soil pollution》2013,224(5):1-6

Mercury and cadmium are priority hazardous substances. Some titanosilicates have been tested for the removal of Cd²⁺ and Hg²⁺ from single solutions by ion exchange. In this work, the competition between both contaminants for the exchanger binding sites of titanosilicate Engelhard titanosilicate material number 4 (ETS-4) was studied by performing batch experiments with aqueous solutions containing the two counter ions. The results evidenced the large capacity of ETS-4 and shown that the cadmium(II) diffusivity through the sorbent is higher than that of mercury(II). Furthermore, the ETS-4 exhibited higher kinetic and equilibrium selectivities for Cd²⁺, which attained values in the ranges 8.9–12.5 and 7.9–12.8, respectively. With respect to modelling, the pseudo-second-order equation described successfully the competitive removal of Cd²⁺ and Hg²⁺.  相似文献   

Pathogenicity and toxicity of Fusarium tucumaniae and Fusarium crassistipitatum to soybean and Arabidopsis thaliana     

Romina G. Rosati  Rocío S. Ramos  María M. Scandiani  Alicia G. Luque  Claudia P. Spampinato 《Plant pathology》2021,70(2):407-416

Sudden death syndrome (SDS) of soybean is a fungal disease caused by at least four distinct Fusarium species: F. tucumaniae, F. virguliforme, F. brasiliense, and F. crassistipitatum. All four species are present in Argentina. These fungi are soilborne pathogens that only colonize roots and cause root necrosis. However, damage also reaches the aboveground part of the plant, and foliar chlorosis and necrosis, followed by premature defoliation, can be observed. Although the pathogenicity and phytotoxicity of F. virguliforme has been well characterized, knowledge regarding disease development by other fungal species is scarce. In this study, two plant species, soybean (Glycine max) and Arabidopsis thaliana, and isolates from two fungal species, F. tucumaniae and F. crassistipitatum, were used to comparatively analyse the fungal pathogenicity and the phytotoxicity of volatile organic compounds (VOCs) and cell-free culture filtrates. Fungal inoculation had a significant effect on plant growth, regardless of the plant species. In addition, infected soybean plants showed disease incidence and foliar and root symptoms. Inhibition of A. thaliana growth was not due to VOCs emitted by fungi. Instead, both pathogens were shown to produce toxins that caused typical SDS foliar symptoms in soybean and root length reduction in A. thaliana. As far as we know, this is the first report that demonstrates that F. tucumaniae and F. crassistipitatum affect A. thaliana growth and emit VOCs, and that F. crassistipitatum produces toxins.  相似文献   

Toward estimating the value of stewardship volunteers: A cost-based valuation approach in King County,Washington, USA     

Jean M. Daniels  Alicia S.T. Robbins  Weston R. Brinkley  Kathleen L. Wolf  John M. Chase 《Urban Forestry & Urban Greening》2014,13(2):285-289

Urban forestry professionals are increasingly challenged to find cost-effective strategies for resource conservation and management. Many organizations partner with citizen groups to host events that enlist volunteers to perform stewardship tasks like tree planting and trail maintenance. These volunteer programs incur costs to both the managing agency and partners, such as staffing, tools, and transportation. Volunteers contribute uncompensated time and expertise. Little is known about these contributions, yet citizen stewards and host groups represent an important human dimension of urban forest management. Using a survey administered to volunteers and host organizations at restoration events in King County Parks, WA, USA, we developed a cost-based approach to estimate the value of stewardship activities that occurred in the spring field season of 2011. Expenditures included volunteer and event host time and direct cost of traveling to and from events, on-site labor, equipment, and preparation costs. Results suggest that contributions made by volunteers and hosts are significant; the combined costs associated with the 17 sampled events was approximately $35,700. These efforts represent a small subset of the more than 1000 volunteer environmental stewardship activities that take place annually in King County.  相似文献   

Acute adverse events associated with ventral slot decompression in 546 dogs with cervical intervertebral disc disease     

Courtney White DVM  Alicia Bays DVM  P. Natalia Henao‐Guerrero DVM  MS  Diplomate ACVAA 《Veterinary surgery : VS》2013,42(7):795-806

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Maintenance of fresh boysenberry fruit quality with UV-C light and heat treatments combined with low storage temperature     

Ariel Vicente  Bernardo Repice  Gustavo Martínez  Alicia Chaves  Pedro Civello 《The Journal of Horticultural Science and Biotechnology》2013,88(2):246-251

Summary

Mature boysenberries (Rubus hybrid) were harvested, heat-treated (45°C for 1 or 3 h or 47°C for 1 h) or exposed to UV-C light (2.3, 4.6 or 9.2 kJ m^–2), and stored at 20°C for 2 d. Fruit treated with 9.2 kJ m^–2 or 45°C for 1 h showed less damaged drupelets per fruit and/or remained firmer than untreated fruit after 2 d. Those treatments were selected for further analyses. In another experiment, boysenberries were either UV-C (9.2 kJ m^–2) or heat-treated (45°C for 1 h) and stored either at 20°C for 1 d or at 0°C for 4 d before transfer to 20°C for 1 d. Both UV-C and heat treatments reduced softening and/or fruit damage. Treated fruit had lower respiration rates and anthocyanin leakage than control fruit suggesting greater tissue integrity. Titratable acidity, pH, total sugar content and antioxidant activity in treated fruit showed fewer changes than in control fruit when stored at 20°C for 1 d. Results suggest that heat or UV-C treatment, alone or in combination with refrigerated storage, may be a useful non-chemical mean of maintaining boysenberry fruit quality and extending postharvest life.  相似文献   

Genetic variability for responses to short‐ and long‐term salt stress in vegetative sunflower plants     

Dolores Bustos  Leandro Ismael Ortega  Alicia Córdoba  Abelardo Vegetti  Edith Taleisnik 《植物养料与土壤学杂志》2012,175(6):882-890

Sunflower (Helianthus annuus L.) has been rated as moderately salt‐resistant, and variability for salt resistance has been detected within this crop. However, variability in salt‐resistance mechanisms has not been assessed. Osmotic tolerance, the relation of salt resistance with whole‐plant Na⁺ and K⁺ distribution and tissue Na⁺ tolerance were investigated in several sunflower inbred lines. Plants were grown under controlled conditions, in pots with sand and perlite irrigated with salinized (NaCl, –0.65 MPa) nutrient solution. Osmotic tolerance was assessed from the initial effects of the salt treatment on plant elongation in eleven sunflower lines. Long‐term salinity responses were evaluated in four of those lines, by assessing whole‐plant growth. A principal components analysis (PCA) was run on relative‐to‐control growth data, and this information was used to establish a relative resistance ranking, which indicated lines HAR2 > HAR1 > HA64 > HAR5. Osmotic tolerance was observed in HA64 and HAR2. The lines showed different degrees of Na⁺ accumulation, it was very low in some of them, but relative salt resistance was not associated to this trait. Tissue Na⁺ tolerance was deduced by comparing the percentage of dead leaves as a function of leaf blade Na⁺ accumulation, and it was higher in HAR1 than in the rest. These results indicate that variability for salt‐resistance mechanisms exists in sunflower. Osmotic tolerance and tissue Na⁺ tolerance were detected in different lines, highlighting that such variability may be exploited for increasing salt resistance in this crop.  相似文献   

Reproductive development, GnRHa-induced spawning and egg quality of wild meagre (Argyrosomus regius) acclimatised to captivity     

Duncan N  Estévez A  Porta J  Carazo I  Norambuena F  Aguilera C  Gairin I  Bucci F  Valles R  Mylonas CC 《Fish physiology and biochemistry》2012,38(5):1273-1286

The objective of the study was to acclimatise wild-caught meagre (Argyrosomus regius) to captivity to produce viable eggs for aquaculture production. Twelve meagre (3 males and 9 females, mean weight?=?20?±?7?kg) were caught and transported to a land-based facility on 26 October 2006. During, March to June 2007, all three males were spermiating and five of the nine females were in vitellogenesis with mean maximum oocyte diameter ≥550?μm. No spontaneous spawning was observed. Two hormone treatments, either a single injection of gonadotropin-releasing hormone agonist (GnRHa, 20?μg?kg(-1) for females and 10?μg?kg(-1) for males) or a slow-release implant loaded with the same GnRHa (50?μg?kg(-1) for females and 25?μg?kg(-1) for males), were used to induce spawning on three different dates on 26 March 2007, 4 May 2007 and 18 April 2008. From each spawning event, the following parameters were determined: fecundity, number of floating eggs, egg size, fertilisation and hatching success, unfed larval survival, and proximal composition and fatty acid profile of the eggs. In 2007, two females that were injected on 26 March and 4 May spawned a total of 5 times producing 9,019,300 floating eggs and a relative fecundity of 198,200 eggs?kg(-1) and two different females that were implanted on the same dates spawned 14 times producing 12,430,000 floating eggs and a relative fecundity of 276,200 eggs?kg(-1). In 2008, a pair that was implanted spawned five times producing a total of 10,211,900 floating eggs and a relative fecundity of 527,380 eggs?kg(-1). The latency period was 48-72?h. Parameters were compared between hormone treatments, date of hormone induction and parents determined by microsatellites. Percentage hatch and egg size were 70?±?0.3% and 0.99?±?0.02?mm, respectively, for GnRHa-implanted fish and were significantly higher (P?相似文献   

Evaluation of permissiveness and cytotoxic effects in equine chondrocytes, synovial cells, and stem cells in response to infection with adenovirus 5 vectors for gene delivery     

Ishihara A  Zachos TA  Bartlett JS  Bertone AL 《American journal of veterinary research》2006,67(7):1145-1155

OBJECTIVE: To evaluate host cell permissiveness and cytotoxic effects of recombinant and modified adenoviral vectors in equine chondrocytes, synovial cells, and bone marrow-derived mesenchymal stem cells (BMD-MSCs). SAMPLE POPULATION: Articular cartilage, synovium, and bone marrow from 15 adult horses. PROCEDURES: Equine chondrocytes, synovial cells, and BMD-MSCs and human carcinoma (HeLa) cells were cultured and infected with an E-1-deficient adenovirus vector encoding the beta-galactosidase gene or the green fluorescent protein gene (Ad-GFP) and with a modified E-1-deficient vector with the arg-gly-asp capsid peptide insertion and containing the GFP gene (Ad-RGD-GFP). Percentages of transduced cells, total and transduced cell counts, and cell viability were assessed 2 and 7 days after infection. RESULTS: -Permissiveness to adenoviral vector infection was significantly different among cell types and was ranked in decreasing order as follows: HeLa cells > BMD-MSCs > chondrocytes > synovial cells. Morphologic signs of cytotoxicity were evident in HeLa cells but not in equine cells. Numbers of transduced cells decreased by day 7 in all cell types except equine BMD-MSCs. Transduction efficiency was not significantly different between the Ad-GFP and Ad-RGD-GFP vectors. CONCLUSION AND CLINICAL RELEVANCE: Sufficient gene transfer may be achieved by use of an adenovirus vector in equine cells. High vector doses can be used in equine cells because of relative resistance to cytotoxic effects in those cells. Greater permissiveness and sustained expression of transgenes in BMD-MSCs make them a preferential cell target for gene therapy in horses.  相似文献