Chitosan/poly(lactic-co-glycolic)acid Nanoparticle Formulations with Finely-Tuned Size Distributions for Enhanced Mucoadhesion

Non-parenteral drug delivery systems using biomaterials have advantages over traditional parenteral strategies. For ocular and intranasal delivery, nanoparticulate systems must bind to and permeate through mucosal epithelium and other biological barriers. The incorporation of mucoadhesive and permeation-enhancing biomaterials such as chitosan facilitate this, but tend to increase the size and polydispersity of the nanoparticles, making practical optimization and implementation of mucoadhesive nanoparticle formulations a challenge. In this study, we adjusted key poly(lactic-co-glycolic) acid (PLGA) nanoparticle formulation parameters including the organic solvent and co-solvent, the concentration of polymer in the organic phase, the composition of the aqueous phase, the sonication amplitude, and the inclusion of chitosan in the aqueous phase. By doing so, we prepared four statistically unique size groups of PLGA NPs and equally-sized chitosan-PLGA NP counterparts. We loaded simvastatin, a candidate for novel ocular and intranasal delivery systems, into the nanoparticles to investigate the effects of size and surface modification on drug loading and release, and we quantified size- and surface-dependent changes in mucoadhesion in vitro. These methods and findings will contribute to the advancement of mucoadhesive nanoformulations for ocular and nose-to-brain drug delivery.

Seasonal analysis of food items and feeding habits of endangered riverine catfish Rita rita (Hamilton, 1822)

This investigation presents the food and feeding activity of and endangered riverine catfish Rita rita, during February 2017-January 2018. A total of 225 fish individuals was analyzed for stomach contents by characterizing the dominant food items and morphometric features. The results divulged ten major food items consumed, preferably fish scales and eggs, teleost fishes, copepods, cladocerans, rotifers, and mollusks. Total length and body weight of fish varied between 9-34 cm (20.53 ± 6.90 cm) and 10-400 g (9125.94 ± 102.07 g), respectively. The index of relative importance (IRI%) showed the importance of rotifers over the other food items. Morisita’s index of diet overlap indicated seasonal variations in catfish diets with summer and monsoon displaying the least overlap, while maximum overlap during monsoon and winter seasons. The non-metric multidimensional scaling (nMDS) indicated the close association between the food items available during summer and winter seasons with a significant difference among the seasons (ANOSIM, R = 0.638, P = 0.013). Levin’s niche breadth index arranged in the order of 0.88>0.81>0.78>0.63>0.43 for the size classes of V, IV, III, II and I, respectively. The PCA explained 95.39% of the total variance among the food items and fish size groups. Small-sized fish individuals displayed a greater correlation with food items suitable for their mouth size. In conclusion, the variety and frequency of food items recorded indicated considerable feeding plasticity and opportunistic feeding behavior with a shift from carnivorous to omnivorous feeding nature. This study could render useful information on the food and feeding habits of R. rita and provide background for preparing its diet for future aquaculture practices.

Trophic ecology of Patagonian flounder Paralichthys patagonicus (Jordan, 1889) in the Argentine-Uruguayan Coastal Ecosystem

Food habits and diet composition of Patagonian flounder Paralichthys patagonicus (Jordan, 1889) were studied on the basis of stomach content analyses from 828 specimens (512 females, 304 males, 12 unsexed) collected during 16 commercial cruises between February 2009 and April 2010 in the Argentine-Uruguayan Coastal Ecosystem (34° S-41° S). A total of 272 stomachs (32.9%) contained food (184 females and 84 males), among which 20 prey taxa were identified. The most important prey category was pelagic fish, primarily Argentine anchovy (Engraulis anchoita), followed by rough scad (Trachurus lathami). Evidence showed that females consumed a higher total wet weight of prey compared to males. Results also suggested a specialised diet over E. anchoita, across all sex and size groups. The estimated trophic level for the population of P. patagonicus was 4.16. This study suggests that P. patagonicus is a tertiary piscivorous consumer of the trophic food web in the region, and reveals changes in the prey consumption compared with previous studies.

A Machine Learning Approach to Assess Differential Item Functioning in Psychometric Questionnaires Using the Elastic Net Regularized Ordinal Logistic Regression in Small Sample Size Groups

Assessing differential item functioning (DIF) using the ordinal logistic regression (OLR) model highly depends on the asymptotic sampling distribution of the maximum likelihood (ML) estimators. The ML estimation method, which is often used to estimate the parameters of the OLR model for DIF detection, may be substantially biased with small samples. This study is aimed at proposing a new application of the elastic net regularized OLR model, as a special type of machine learning method, for assessing DIF between two groups with small samples. Accordingly, a simulation study was conducted to compare the powers and type I error rates of the regularized and nonregularized OLR models in detecting DIF under various conditions including moderate and severe magnitudes of DIF ( DIF = 0.4 and 0.8 ), sample size ( N ), sample size ratio ( R ), scale length ( I ), and weighting parameter ( w ). The simulation results revealed that for I = 5 and regardless of R , the elastic net regularized OLR model with w = 0.1 , as compared with the nonregularized OLR model, increased the power of detecting moderate uniform DIF ( DIF = 0.4 ) approximately 35% and 21% for N = 100 and 150 , respectively. Moreover, for I = 10 and severe uniform DIF ( DIF = 0.8 ), the average power of the elastic net regularized OLR model with 0.03 ≤ w ≤ 0.06 , as compared with the nonregularized OLR model, increased approximately 29.3% and 11.2% for N = 100 and 150 , respectively. In these cases, the type I error rates of the regularized and nonregularized OLR models were below or close to the nominal level of 0.05. In general, this simulation study showed that the elastic net regularized OLR model outperformed the nonregularized OLR model especially in extremely small sample size groups. Furthermore, the present research provided a guideline and some recommendations for researchers who conduct DIF studies with small sample sizes.

Mapping trait versus species turnover reveals spatiotemporal variation in functional redundancy in a plant-pollinator network

Functional overlap between species (redundancy) shapes competitive and mutualistic interactions, determining community responses to perturbations. Most studies view functional redundancy as static, even though individuals within species vary in traits over seasonal or spatial gradients. Consequently, we lack knowledge on trait turnover within species, how functional redundancy spatiotemporally varies, and when and where interaction networks are vulnerable to functional loss. Studying an Arctic bumblebee community, we investigated how body-size turnover with elevation and over a season shapes their host-plant interactions, and test how sensitive networks are to sequentially losing body-size groups. With trait turnover being larger than species, we found: i) late-season networks were less specialised when nodes comprised functionally similar bumblebees; ii) removal of bumblebee-body-size groups over species accelerated coextinction of host plants, with the magnitude varying in space and time. We demonstrate functional redundancy can vary spatiotemporally, and functional loss impacts interaction partners more than expected from species loss alone.

REPRESENTATION OF THE SPECIFIC SURFACE AREA OF A POROUS MEDIUM BY STATISTICAL CONTINUOUS MONOMIAL FUNCTIONS

Удельная поверхность пористых сред является важным геометрическим параметром в расчетах процессов пищевых систем и оборудования для их переработки. Расчетные формулы процессов тепло- и массообмена в настоящее время содержат осредненные значения геометрических параметров, получаемые в эксперименте. Использование формул удельной поверхности по осредненным характеристикам пористой среды существенно ограничивает точность и надежность расчетов. Получены непрерывные одночленные по всему диапазону размеров сообщающихся пор расчетные формулы удельной поверхности, основанные на функции распределения плотности вероятности размеров сообщающихся пор разных модельных конфигураций в полиразмерной дисперсной (несцепленной) и связной (сцепленной) пористых средах для двух видов исходных формул удельной поверхности, различных видов модельных поперечных сечений и длины пор. Проведен их сравнительный анализ. Установлено, что на расчет удельной поверхности влияет моделируемая длина пор. Вид поперечного сечения не влияет на расчет удельной поверхности. Полученные формулы позволяют вычислять удельную поверхность для ансамбля отдельных размерных групп пор и в целом для всей совокупности их размеров. Приведен пример расчета по полученным формулам. The specific surface area of porous media is an important parameter in the calculations of the processes of food systems and equipment. The calculated formulas of the heat and mass transfer processes currently contain the averaged values of the geometric parameters obtained in the experiment. The use of formulas the specific surface area based on the averaged characteristics of a porous medium significantly limits the accuracy and reliability of calculations. Continuous monomial calculated formulas for the specific surface and based on the function of the probability density of the size distribution open pores ware obtained. Their comparative analysis is carried out. It was found that the transverse shape is not reflected in the formulas for the specific surface area, but the simulated pore length does. The specific surface area formulas allow calculating the specific surface area for an ensemble of separate size groups of pores and, in general, for the entire set of their sizes. An example of calculation by the obtained formulas is given.

Simulation Model of Selective Assembly of the Conrod-Piston Group Unit of Internal Combustion Engines, Taking into Account Measurement Errors During Sorting

The process of selective assembly of the conrod-piston group of an internal combustion engine, which provides the required accuracy of the connections, is considered. The functioning of a unit consisting of three main elements is described, the scheme of the assembly set-making is shown. The simulation model of a one-parameter selective assembly of three elements has been modernized by taking into account measurement errors arising from sorting into size groups. The modeling of the assembly process of the unit for a specific engine model has been carried out. A dependence is obtained that connects the required output indicator of the technological process with the parameter of the measurement quality. This research will allow solving the metrological problem associated with the choice of the optimal accuracy of measuring equipment under technical and economic constraints.

PSII-11 Herd size associated with sow lifetime performance in Spanish breeding herds

It is critical for producers to maximize sows’ reproductive potential in commercial herds in order to improve economic efficiency. While it is generally known that large herds have better reproductive performance than small herds, few studies have assessed how much the lifetime reproductive performance of sows is associated with herd size. Therefore, our objective was to examine the relationship between six herd size groups and sow lifetime performance. Data were extracted from 166,335 sows which were entered into 155 Spanish breeding herds from 2011 - 2013 and removed by 2017. Herds were categorized into six groups based on the 10th, 25th, 50th, 75th and 90th percentiles of average sow inventory in 2016: 87 - 195, 196 - 342, 343 - 596, 597 - 1,025, 1,026 - 2,152 and 2,153 - 3,669 sows. A two-level linear mixed-effects model was applied to examine the relationship between herd size and reproductive performance of sows (SAS University Edition). No differences were found between herd size groups and either lifetime total born or lifetime piglets born alive. However, the largest herd group had 23.0 fewer lifetime nonproductive days (NPD), and 2.1 more annualized lifetime piglets weaned than the mid-size (343 - 596 sows) herds (P < 0.05). Also, parity at removal was 0.3 lower in the largest herds than the mid-size herds (P < 0.05). Furthermore, the largest herds also had 0.8 - 1.0 days shorter weaning-to-first-mating interval (WMI), 2.8 - 4.9% higher farrowing rates and 10.2 - 11.9 days shorter repeat intervals than the mid-size herds (P < 0.05). In conclusion, the shorter WMI, fewer NPD and improved reproductive productivity in the largest herds suggest that these herds have better lactational management and quicker culling decision making than mid-size herds.

Investigation on Larvicidal Efficacy of Two Native Ornamental Murrels of Assam under Controlled Condition

Background: It is widely reported that exotic larvicidal fishes like Gambusia and Poecilia have adverse impact on the native aquatic fauna. The present study highlights the efficacy of two colourful native murrels, primarily designated as ornamental fish, Channa bleheri and Channa stewartii as biocontrol agent of mosquito larvae. Methods: Live specimens of Channa bleheri and C. stewartii, collected from the wetlands of Tinsukia district of Upper Assam, were assessed for their larvivorous potential at individual and group levels during day and night by dividing the specimens into two size groups. After 12 hour and 24 hour starvation, the test specimens (mean size for small group 8.67 - 9.17 cm and that of large group 11.63-13.27 cm) were given known number of mosquito larvae and recorded the consumption rate. Result: The predation rate varied from 33.3±4.36 to 71.6±5.15/min for Channa bleheri and that of C. stewartii from 16.3±0.95 to 68.2±2.77/min. In both species, smaller sized specimens were better performers as predators. Predation rate at 12 and 24 hrs of starvation and between day and night proved that these native murrels are excellent predators of mosquito larvae.

ON FERTILITY OF BLACK-BACKED SHAD ALOSA KESSLERI KESSLERI (GRIMM, 1887)

The article highlights the results of studying the individual absolute fertility (IAF) of black-backed shad Alosa kessleri kessleri (Grimm, 1887). The data were obtained during the species’ spawning run in the Volga River. A positive correlation was established between IAF and the linear indicators, weight and age of producers. IAF ranged from 38.0 to 333.9 thousand eggs. The average absolute fecundity of herring varied from 38.8 to 259.2 thousand eggs. In the 1970s black-backed shad of 26-42 cm long had fluctuations in the average absolute fecundity from 88.4 to 258.5 thousand eggs. At the present stage, the size range of spawning shoals suggests that maturity in black-backed shad occurs at a body length of 22-45 cm, the reproductive capacity is regulated by early maturation. The results of studies on the fertility of black-backed herring of various lengths in 1 g of ovary have been obtained. There has been registered a wide range of fluctuations in the number of eggs (from 4033 to 14147 pcs). Differences in the size of ovaries indicate a qualitative definiteness of the physiological readiness of females in the pre-spawning period. The fluctuations in the average individual absolute fertility were revealed depending on body weight and age. Fertility in one-size groups and the reproductive capacity of the population as a whole change due to habitat conditions. The conditional indicator of the population fertility was calculated. The results of the obtained fertility data compared with the data of previous years indicate a 1.5-fold decrease in reproductive capacity of the population at the present time, which indicates a stressed state of the reproductive capacity of female species