Influence Of Particle Size Fraction Research Articles

Influence of particle size fraction and bioactive compound contents on the biological activities of Solanum torvum L. leaf powder extracts

This study investigates the bioactive compound content and biological activities of raw powder extracts and particle size fractions from Solanum torvum leaves. The leaves, harvested from Douala, were processed into powders and subsequently divided into different fractions. Methanolic extracts of these powders were analyzed for their content of bioactive compounds (total polyphenols, total flavonoids, and condensed tannins), antioxidant (DPPH, ABTS, FRAP assays), and antimicrobial (bacterial and fungal) activities. The particle size fraction of 250-400 µm constitutes the largest proportion (33.41%) of the raw powder. The highest contents of bioactive compounds are found in the 200-250, 400-500, and < 125 µm fractions for total polyphenols (44.62 ± 0.19 mg GEA/100 ml extract), total flavonoids (14.47 ± 0.37 mg QE/100 ml extract), and condensed tannins (22.79 ± 0.12 mg CE/100 ml extract), respectively. The antioxidant activity of extracts from 500-800µm fraction improved their DPPH and ABTS assays by 31.50% and 40.44% compared to the raw powder. The same fraction (500-800 µm) and the raw powder extracts demonstrated bactericidal activities, while the 125-200, 200-250, and ≥ 800 µm fraction extracts exhibited moderate and significant antifungal activities against several bacterial and fungal strains, respectively. These biological activities are primarily attributed to the average flavonoid contents, which become more accessible in extracts after fractionation. This method of processing powder suggests that no plant powder should be disregarded or rejected due to its low content of bioactive compounds.

Particle size fractions and pedogenesis of coastal plain sands

This study established the influence of particle size fractions (psf) on the characteristics of coastal plain soils of southeastern Nigeria. A total of 180 samples were collected according to genetic horizons on 30 profile pits prepared on the upper, middle, and lower slope positions of 10 toposequences. The samples were analyzed for hydraulic conductivity, pH, bulk density, moisture content, electrical conductivity, exchangeable bases and acidity, organic carbon, available and total phosphorus (P) contents, dithionite citrate bicarbonate (DCB) extractable and amorphous iron and aluminum (Al) contents. Particle size distribution was also analyzed, including total sand, very coarse, coarse, medium, fine and very fine sand, clay, and silt. Statistical analysis carried out included analysis of variance, correlation, and principal component. Very coarse sand influenced the distribution of P and DCB-Al within the toposequences. Active pedogenesis was located in the fourth horizons of the profiles that manifest inverse relationship of very coarse sand with P and amorphous Al. The association between sand particles and sesquioxides, especially of Al, was responsible for the low pH associated with coastal plain soils. Principal component analysis confirmed that total sand fractions are the determinants of rate and extent of pedogenesis and influences the properties of coastal plain soils.

Evaluation of bioaccessible arsenic in fly ash by an in vitro method and influence of particle-size fraction on arsenic distribution

A huge amount of fly ash is produced by coal-fired power plants every year in China and leads to increasing environmental problems associated with disposal and treatment. It will be very helpful for the study of management and disposal of solid waste to understand the bioaccessibility and environmental behaviors of arsenic in fly ash. In this paper, an in vitro physiologically-based extraction test was applied to estimate the solubility and bioaccessibility of arsenic in fly ash in the human gastrointestinal tract. The fly ash samples were sieved into different fractions with different particle sizes (100–60, 60–10, 10–2.5, <2.5 μm). The influence of particle size on both total and bioaccessible arsenic was also investigated. The results demonstrated that arsenic concentrations in fly ash were significantly correlated with particle size. The proportion of bioaccessible arsenic (gastric and intestinal arsenic) accounting for the total arsenic was in the range of 36–67 %. The statistic analysis indicated that total arsenic in fly ash was linearly correlated with bioaccessible arsenic. The results illustrated that bioaccessible arsenic was dominated by total arsenic.

Influence of particle size fractions on the physicochemical properties of maize flour and textural characteristics of a maize‐based nonfermented food gel

SummaryThe physicochemical properties of fractionated maize flour and the textural characteristics of a maize‐based nonfermented food gel (maize tuwo) prepared from the respective fractionated flours were evaluated. The maize flour was fractionated into four fractions: &lt;75 μm, 75–150 μm, 150–300 μm, 300–425 μm and whole meal (&lt;425 μm). There were variations in the selected chemical constituents of fractionated maize flour including protein (2.9–4%), ash (0.80–0.97%), crude fibre (0.73–0.91%) and damaged starch (10.1–17.4%). The fractionated maize flour gave variable bulk density (0.80–0.93 g cm−3), water absorption capacity (1.9–2.1 g g−1) and oil absorption capacity (1.7–2.1 g g−1). The colour characteristics of the fractionated maize flour and the pasting properties were all affected by the fractionation. The cohesiveness index (strain at peak compressive force) of the food gel from the flour fractions ranged between 15% and 19.5% while the softness index of the food gel ranged between 16.7 and 17.5 mm. The relative high cohesiveness and softness indexes (i.e. 19.5% and 17.4 mm respectively) of maize tuwo prepared from the flour fraction of 75–150 μm can predispose the food gel towards easier hand‐mouldability and swallowability respectively; being important quality indicators for its acceptability.

Relationships between soil particle size fractions and infiltrability

The influence of particle size fractions on infiltrability was investigated in soils sampled across Namibia and western South Africa. Infiltrability was determined using a laboratory technique calibrated with rainfall simulation, which measures the passage of a suspension of soil particles through a packed soil column. Water-dis-persible soil particle size fractions were determined using a high definition digital laser particle size analyser. Total (calgon-dispersed) particle size fractions were determined by hydrometer. Dispersion of soil particles resulting in crust formation on the soil surface appeared to be a main mechanism reducing infiltrability. Water-dispersible clay and fine silt determined by laser analyser showed higher correlation with infiltrability (r2 = −0.43 for clay and −0.47 for fine silt) than total clay and fine silt determined by hydrometer (r2 = −0.30 and −0.28, respectively). Clay, fine silt, coarse silt, very fine sand and fine sand fractions (<120 µm) showed a probable plasmic role in soil crusts. At a content of these fractions > 5% infiltrability was inevitably restrained. The 120–200 µm fraction showed no clear relationship with infiltrability. It played either a plasmic or skeletal role, depending on its ratio to the <120 µm and >200 µm fractions. Fine, medium and coarse sand fractions (>200 µm) showed a probable skeletal role in soil crusts, i.e. forming pores that enhanced infiltrability. At levels >50% of these fractions, infiltrability was potentially maximal. This potentially maximal infiltrability was also explained by the concomitant decrease in plasmic fraction content with an increase of the skeletal fraction.

The influence of chitosan on in vitro properties of Eudragit RS microspheres.

Eudragit RS microspheres containing chitosan hydrochloride were prepared by the solvent evaporation method using acetone/liquid paraffin solvent system and their properties were compared with Eudragit RS microspheres without chitosan, prepared in our previous study. Different stirring rates were applied (400-1200 rpm) and drug content, Higuchi dissolution rate constant, surface and structure characteristics of the microspheres were determined for each size fraction. An increase in average particle size with a reduction of stirring rate appeared in limited interval in both series. The average particle size of microspheres without chitosan, prepared at the same stirring rate, was smaller. Pipemidic acid content increased with increasing fraction particle size, but not with increasing stirring rate as it was observed for microspheres without chitosan. We presume that high pipemidic acid content in larger microspheres is a consequence of cumulation of undissolved pipemidic acid particles in larger droplets during microspheres preparation procedure. Pipemidic acid release was faster from microspheres with chitosan and no correlation between Higuchi dissolution rate constant and stirring rate or fraction particle size was found, though it existed in the system without chitosan. Structure and surface characteristics of microspheres observed by scanning electron microscope (SEM) were not changed significantly by incorporation of chitosan. But in contrast with microspheres without chitosan, the surface of chitosan microspheres was more porous after three hours of dissolution. It is supposed that the influence of particle size fraction and stirring rate on release characteristics is expressed to a great extent through porosity and indirectly through total effective surface area, but the incorporation of highly soluble component i.e. chitosan salt hides these effects on drug release. In conclusion, changes in biopharmaceutical properties due to varying stirring rate and fraction particle size exhibited the same direction as those reported for the microspheres without chitosan, although they are less expressed because of increased experimental variability, likely caused by chitosan.

Near Infrared Spectroscopy of Fuel Contaminated Sand and Soil. I. Preliminary Results and Calibration Study

Regional areas may be contaminated by the past activities of the chemical and oil industries and of the military. Therefore, the present study was undertaken to test the possibilities of near infrared (NIR) reflectance spectroscopy for direct detection and determination of oil and fuel contaminations. If reliable results are obtained NIR reflectance spectroscopy could be a valuable part of land remediation processes. Preliminary investigations showed that it is possible to distinguish samples of stone chippings, sand, cultivated soil, humus and potting soil by multivariate data analysis. After spiking with gasoline, diesel, motor oil and synthetic hydrocarbon mixtures (BTEX) sand rather than cultivated soil shows obvious spectral absorptions due to contaminations higher than 1% (w/w). The influence of particle size fractions has been investigated in detail using dry sand sieved to &lt; 500 μm (fine), 500–800 μm (medium) and &gt;800 μm (coarse). Contaminations in fine and medium fractions often can be modelled with only one intensity at sufficiently low calibration error, SEC. With coarse fractions SEC is three times higher. Models based on derivative spectra have no significant advantage. In general, mean centring results in more pronounced error minima than multiplicative scatter correction (MSC). Partial least squares (PLS) models can be fitted to obtain any wanted SEC even by cross-validation. For comparable SEC, PLS models in general do not need more factors if samples become more inhomogeneous. Data pre-processing techniques such as Kubelka–Munk transformation, Saunderson correction, MSC and combinations thereof have been tested. Adequate sample variation of the diffuse reflectance fraction of detected light according to the Saunderson model could improve the performance of calibration models. The best values for standard error of prediction, SEP, are obtained if calibration models are derived from sets of spectra of sieved samples and used for contamination prediction of natural samples, and not vice versa. Spectra of contaminated soil and humus need cleverer spectral selection and pre-processing for better performance of calibration models.