Search results for "SIZE"
showing 10 items of 2718 documents
Development of a coupled diffusion denuder system combined with gas chromatography/mass spectrometry for the separation and quantification of molecul…
2009
This study concerns the development of a coupled diffusion denuder system capable of separating and quantifying gaseous molecular iodine (I(2)) and two other highly reactive iodine species, ICl and HOI, which are collectively named activated iodine compounds (AIC). Both I(2) and AIC are key species in the atmospheric chemistry of iodine. 1,3,5-Trimethoxybenzene (1,3,5-TMB)- and alpha-cyclodextrin/(129)I(-) (alpha-CD/(129)I(-))-coated denuders proved to be suitable for the collection of gaseous AIC and I(2), respectively. The experimental collection efficiencies for AIC (tested as ICl) and I(2) agreed well with the theoretical values for gas flow rates in the range between 300 and 1800 mL mi…
Photocrosslinking of dextran and polyaspartamide derivatives: a combination suitable for colon-specific drug delivery.
2007
Abstract The aim of this study was to prepare and characterize novel hydrogels with polysaccharide–polyaminoacid structure, able to undergo an enzymatic hydrolysis in the colon and potentially useful for treating inflammatory bowel diseases (IBD). Starting materials were methacrylated dextran (DEX-MA) and methacrylated α,β-poly(N-2-hydroxyethyl)- dl -aspartamide (PHM). These polymers were photocrosslinked by exposure of their aqueous solutions at 313 nm without photoinitiators. Different samples, shaped as microparticles, were obtained as a function of polymer concentration and irradiation time. FT-IR analysis confirmed the occurrence of a co-crosslinking between DEX-MA and PHM in all exper…
Optimum and Maximum Host Sizes at Parasitism for the Endoparasitoid <I>Hyposoter didymator</I> (Hymenoptera: Ichneumonidae) Differ Greatl…
2007
Host size is considered a reliable indicator of host quality and an important determinant of parasitoid fitness. Koinobiont parasitoids attack hosts that continue feeding and growing during parasitism. In contrast with hemolymph-feeding koinobionts, tissue-feeding koinobionts face not only a minimum host size for successful development but also a maximum host size, because consumption of the entire host is often necessary for successful egression. Here we study interactions between a generalist tissue-feeding larval endoparasitoid, Hyposoter didymator Thunberg (Hymenoptera: Ichneumonidae) and two of its natural hosts, Spodoptera exigua Hübner and Chrysodeixis chalcites Esper (Lepidoptera: N…
Comportamiento de las correlaciones producto-momento y tetracórica-policórica en escalas ordinales: un estudio de simulación
2017
El análisis estadístico multivariante de escalas de respuesta tipo Likert, dado su empleo generalizado, resulta un tema controvertido en la comunidad científica, principalmente desde la especificación del problema de la medida. Este trabajo tiene como objeto estudiar cómo afectan diversas condiciones de estas escalas ordinales al cálculo de los coeficientes de correlación producto-momento y tetracórico-policórico. Para ello, se aplica un estudio de simulación en el que se generaron 90 bases de datos con 10 ítems cada una, controlando las siguientes variables: número de categorías de respuesta, distribución simétrica o asimétrica de los datos, tamaño de la muestra y nivel de relación entre l…
Molecular dynamics of electrosprayed water nanodroplets containing sodium bis(2-ethylhexyl)sulfosuccinate
2013
The behavior of aqueous solutions of sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) subject to electrospray ionization (ESI) has been investigated by molecular dynamics (MD) simulations at three temperatures (350, 500 and 800 K). We consider several types of water nanodroplets containing AOTNa molecules and composed of a fixed number of water molecules (1000), N(AOT)(0) AOT(-) anions (N(AOT)(0) = 0, 5, 10) and N(Na)(0) sodium ions (N(Na)(0) = 0, 5, 10, 15, 20): in a short time scale (less than 1 ns), the AOTNa molecules, initially forming direct micelles in the interior of the water nanodroplets, are observed in all cases to diffuse nearby the nanodroplet surface, so that the hydrophilic …
Optimal sample allocation conditioned on a small area model, estimator, and auxiliary data
2018
We have studied optimal sample allocation, associated with small area estimation, when the objective is to obtain as accurate estimates as possible, for the population and for the subpopulations, called as areas here. It is a question of a two-level optimization problem. The basic premise is composed of planned areas, stratified sampling, and small overall sample size predetermined by restricted time and budget resources. Low sample sizes are common in market surveys. During this thesis, we have developed new allocation methods, based on a small area model, estimator, and auxiliary data. The final method, the three-term Pareto allocation, is based on the three terms of the mean-squared erro…
Choose as many as you wish: Consumer satisfaction and purchase rate increase when choice from large assortments is flexible as opposed to constrained
2020
Five studies across a range of domains show that consumers who can choose as many alternatives as they wish (“flexible choice”), report more positive affective states and purchase more than those who have to choose a pre-defined quantity of products (“constrained” choice). The benefits of choice “flexibility” are stronger in large than small assortments, and are replicated in field and laboratory settings: when people chose cookies after a meal in a restaurant, possible dating partners on a simulated dating website, energy bars from descriptions, and soaps for personal use. The findings have theoretical implications for advancing choice-overload research, as well as practical implications f…
Facilitators of and Barriers to Sustainable Development in Small and Medium-Sized Enterprises: A Descriptive Exploratory Study in Romania
2021
In the context of growing concerns regarding the deterioration of the environment and the increase in social inequalities, the concept of sustainability emerged as a response of companies, in order to contribute to community goodwill. The drivers and obstacles for the businesses engaging in sustainable policies have been explored at large by scientific literature. However, research gaps were observed, namely regarding SMEs, that tend to have a less formal and more fragmented approach to sustainability. The goal of our study is to determine the main barriers and facilitators for sustainability that Romanian SMEs face, and the connections between them and with the firms’ characteristics. Our …
Simulation of granular organic fertilizer application by centrifugal spreader
2021
There is no specialized equipment designed to spread granular cylindrical organic fertilizer in the soil. There are also no rational recommendations available on how to spread this type of fertilizer. Mineral fertilizer spreaders are most often used for spreading granulated organic fertilizer. However, these fertilizers are significantly different from mineral fertilizers. Due to these differences, organic granular fertilizers often are spread unevenly, and the fertilizer does not reach the required working width. Furthermore, the rate of spreading is not accurate, and the fertilizer is often crushed too much. The objective of this research is to develop a simulation model for granular orga…
Influence of bacterial physiology on processing of selenite, biogenesis of nanomaterials and their thermodynamic stability
2019
We explored how Ochrobactrum sp. MPV1 can convert up to 2.5 mM selenite within 120 h, surviving the challenge posed by high oxyanion concentrations. The data show that thiol-based biotic chemical reaction(s) occur upon bacterial exposure to low selenite concentrations, whereas enzymatic systems account for oxyanion removal when 2 mM oxyanion is exceeded. The selenite bioprocessing produces selenium nanomaterials, whose size and morphology depend on the bacterial physiology. Selenium nanoparticles were always produced by MPV1 cells, featuring an average diameter ranging between 90 and 140 nm, which we conclude constitutes the thermodynamic stability range for these nanostructures. Alternativ…