Relevant Physicochemical Characteristics Research Articles

SYNTHESIS AND CHARACTERIZATION OF LOW-COST PLASTICIZED POLYMERIC MEMBRANES FOR SEPARATION OF BIVALENT CATIONS

Recently, polymer inclusion membranes (PIMs) have surfaced as a viable solution for selective transport and metallic ions separation. The efficiency of such membranes is subject to a number of factors, including the preparation method and relevant physico-chemical characteristics. In this paper, an improvement of a novel category of PIMs for performing ions separation is reported. The membranes were prepared using a mixture of two polymers: cellulose triacetate (CTA) and poly(methyl methacrylate) (PMMA), three different carriers, Aliquat 336 (basic), di-(2-ethylhexyl) phosphoric acid (D2EHPA) (acid) and tributyl phosphate (TBP) (neutral) and plasticized by dioctyle phthalate (DOP). All synthesized membranes were characterized using Fourier Transform Infrared (FTIR) spectroscopy, Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). A study of the transport of Co(II), Cu(II), Ni(II) and Pb(II) species using the synthesized membranes was conducted. Our results indicate that facilitated transport through PIMs is an effective way of solving the permanent problem of membrane stability.

The promoting effect of electron beam irradiation on enzymatic saccharification and alcohol fermentation of sorghum meal: Related mechanisms

In this study, sorghum meal underwent 2–10 kGy electron beam irradiation (EBI) to investigate alterations in its elemental composition, relevant physicochemical characteristics, and enzymatic hydrolysis fermentation properties. The results indicated a decrease in amylose content and an increase in reducing sugar content in sorghum meal after EBI, along with severe damage to the internal structure of starch granules, leading to increased solubility in water. Furthermore, irradiation enhanced the shear resistance and gelatinization stability of sorghum meal paste. Most importantly, EBI-induced degradation of sorghum starch molecules enhanced their susceptibility to interact with α-amylase, significantly improving the enzymatic hydrolysis and alcohol fermentation efficiency of sorghum meal. At an irradiation dose of 8 kGy, raw and cooked sorghum meal exhibited a 43.40% and 33.33% increase in ethanol concentration and a 43.44% and 30.29% increase in ethanol yield, respectively. This finding indicated that irradiation is an effective pretreatment method for starch-based ethanol fermentation.

CHARACTERISTICS OF BIOCHAR PRODUCED FROM CELLULOSE FOR CAPTURE OF ATMOSPHERIC CO2"

"Biochar (BioC) production from biomass is attractive due to its low cost and relevant physicochemical characteristics. Within this context, the objective of the present work was to produce BioC from cellulose of Pinus elliotti, with different pyrolysis parameters, intended for use in CO2 adsorption from the atmosphere. As main results, the produced BioC presented a porous structure, with a fibrous characteristic, due to the raw material used (cellulose). Also, the biochar prepared at 800 °C (P800) presented higher specific surface area and total pore volume than that prepared at 600 °C (P600), due to the higher pyrolysis temperature applied. On the other hand, P600 presented a higher conversion of cellulose to BioC. Due to these characteristics, P800 presented greater ability to adsorb CO2. Thus, a potential use for BioC was identified in this work."

Revealing Physiochemical Factors and Zooplankton Influencing Microcystis Bloom Toxicity in a Large-Shallow Lake Using Bayesian Machine Learning.

Toxic cyanobacterial blooms have become a severe global hazard to human and environmental health. Most studies have focused on the relationships between cyanobacterial composition and cyanotoxins production. Yet, little is known about the environmental conditions influencing the hazard of cyanotoxins. Here, we analysed a unique 22 sites dataset comprising monthly observations of water quality, cyanobacterial genera, zooplankton assemblages, and microcystins (MCs) quota and concentrations in a large-shallow lake. Missing values of MCs were imputed using a non-negative latent factor (NLF) analysis, and the results achieved a promising accuracy. Furthermore, we used the Bayesian additive regression tree (BART) to quantify how Microcystis bloom toxicity responds to relevant physicochemical characteristics and zooplankton assemblages. As expected, the BART model achieved better performance in Microcystis biomass and MCs concentration predictions than some comparative models, including random forest and multiple linear regression. The importance analysis via BART illustrated that the shade index was overall the best predictor of MCs concentrations, implying the predominant effects of light limitations on the MCs content of Microcystis. Variables of greatest significance to the toxicity of Microcystis also included pH and dissolved inorganic nitrogen. However, total phosphorus was found to be a strong predictor of the biomass of total Microcystis and toxic M. aeruginosa. Together with the partial dependence plot, results revealed the positive correlations between protozoa and Microcystis biomass. In contrast, copepods biomass may regulate the MC quota and concentrations. Overall, our observations arouse universal demands for machine-learning strategies to represent nonlinear relationships between harmful algal blooms and environmental covariates.

PERFILES DE DENSIDAD DE RADÓN EN POROS ALVEOLARES: UNA APLICACIÓNDEL FORMALISMO DE ECUACIÓN INTEGRAL

In this work, we obtained density profiles of Radon particles near the alveolar wall surface by the development of a theoretical model that describes the interaction between such particles and the alveolar wall cells. The model captures relevant biological and physicochemical characteristics such as the width of the alveolar wall and the energy required for the Radon particles to pass through it. The system satisfies the conditions to be considered in thermodynamic equilibrium and under normal pressure and temperature conditions. We numerically solved the Ornstein-Zernike equations derived from the integral-equation formalism and showed the effects of changing the alveolus size, the alveolar wall width, and the energy required to pass through its Radon density profiles. Our method is a helpful tool in biophysics and other related areas.

Geochemistry of selenium, barium, and iodine in representative soils of the Brazilian Amazon rainforest

The Amazon rainforest is a heterogeneous ecosystem and its soils exhibit geographically variable concentrations of trace elements. In this region, anthropic activities - e.g., agriculture and mining - are numerous and varied, and even natural areas are at risk of contamination by trace elements, either of geogenic or anthropogenic origin. A reliable dataset of benchmark values for selenium (Se), barium (Ba), and iodine (I) concentrations in soils is needed for use as a reference in research and public policies in the region. In this study, 9 selected sites in the Brazilian Amazon rainforest within areas represented by Oxisols and Ultisols were assessed for relevant soil physicochemical characteristics, along with the concentrations of total Se (SeTot), total Ba (BaTot), and sequentially-extracted soluble Se (SeSol) and adsorbed Se (SeAd) in 3 different soil layers (0–20, 20–40, and 40–60 cm). In addition, organically bound-Se (SeOrg) and total I (ITot) concentrations in the surface layer (0–20 cm) were measured. Soil Se concentrations (SeTot) were considered safe and are likely a result of contributions of sedimentary deposits from the Andes. Available Se (SeSol + SeAd) accounted for 4.5% of SeTot, on average, while SeOrg in the topsoil accounted for more than 50% of SeTot. Barium in the western Amazon (state of Acre) and central Amazon (Anori, state of Amazonas) exceeded national prevention levels (PVs). Furthermore, the average ITot in the studied topsoils (5.4 mg kg−1) surpassed the worldwide mean. Notwithstanding, the close relationship found between the total content of the elements (Se, Ba, and I) and soil texture (clay, silt, and sand) suggests their geogenic source. Finally, our data regarding SeTot, BaTot, and ITot can be used to derive regional quality reference values for Amazon soils and also for updating prevention (PV) and investigation (IV) values established for selected elements by the Brazilian legislation.

Crab‐driven processing does not explain leaf litter‐deposition in mangrove crab burrows

AbstractMany mangrove crab species drag freshly fallen leaf litter into their burrows and store it there for some time prior to consumption. Potential explanations for this behavior include (a) avoidance of competition for a scarce resource, (b) prevention of removal of a scarce resource upon tidal outwelling, or (c) processing of an initially unpalatable food source, be it physically through leaching, through the activity of the sediment microbiota, or driven by the activity of the crab itself. To test the latter, we study the effect of burying mangrove leaf litter on two relevant physicochemical litter characteristics and on its digestibility to crabs in a laboratory experiment, using artificial substratum with low microbial activity. Freshly fallen leaves of two common mangrove species, Bruguiera gymnorhiza and Ceriops tagal, were left for two weeks either inside burrows used by Neosamartium asiaticum (Sesarmidae), or on top of the substratum, before they were offered to the crabs as food. Leaf toughness and total phenolic content differed significantly between mangrove species. Upon two weeks of decay, phenolic content of both leaf litter species and toughness of B. gymnorhiza​ changed significantly. However, neither litter characteristcs nor assimilation efficiency differed between treatments. We conclude that storing mangrove leaf litter in crab burrows in a microbe‐poor environment does not affect litter digestibility. Hence, crabs themselves do not contribute to litter processing during storage inside the burrow. If it is litter processing, rather than the avoidance of competition or litter removal by tides, that renders the storage of litter inside the burrow advantageous, it will be microbial activity that drives this process. Further studies should explicitly focus on processing through the activity of the sediment microbiota.

Dissolution kinetics of zinc oxide and its relationship with physicochemical characteristics

Dissolution kinetics of zinc oxide (ZnO) powders used as feed additives for supplementation in diet of animals is studied in relation to the powder physicochemical characteristics. The fundamental issue of discrimination of reaction-limited or diffusion-limited dissolution into a stirred liquid medium is addressed. Relationships between dissolution kinetics and physicochemical properties are investigated for a set of 34 ZnO samples of various origins. A principal component analysis allows sorting ZnO samples in three clusters having different physicochemical properties. A correlation analysis discloses the most relevant physicochemical characteristics affecting dissolution: density, agglomerate size and specific surface area. Coarse particles dissolve in a reaction-limited process according to their specific surface area. Fine aggregated particles dissolve in 2 steps: reaction-limited dissolution at the surface of ZnO primary particles, followed by diffusion in the quiescent liquid medium between primary particles to the stirred bulk aqueous medium. A reaction-diffusion model is proposed.

Shorter Antibacterial Peptide Having High Selectivity for E. coli Membranes and Low Potential for Inducing Resistance.

Antimicrobial peptides (AMPs) have been recognised as a significant therapeutic option for mitigating resistant microbial infections. It has been found recently that Plasmodium falciparum-derived, 20 residue long, peptide 35409 had antibacterial and haemolytic activity, making it an AMP having reduced selectivity, and suggesting that it should be studied more extensively for obtaining new AMPs having activity solely targeting the bacterial membrane. Peptide 35409 was thus used as template for producing short synthetic peptides (<20 residues long) and evaluating their biological activity and relevant physicochemical characteristics for therapeutic use. Four of the sixteen short peptides evaluated here had activity against E. coli without any associated haemolytic effects. The 35409-1 derivative (17 residues long) had the best therapeutic characteristics as it had high selectivity for bacterial cells, stability in the presence of human sera, activity against E. coli multiresistant clinical isolates and was shorter than the original sequence. It had a powerful membranolytic effect and low potential for inducing resistance in bacteria. This peptide’s characteristics highlighted its potential as an alternative for combating infection caused by E. coli multiresistant bacteria and/or for designing new AMPs.

Visible-to-ultraviolet (

In this article, visible-to-ultraviolet photon upconversion (UV-UC) by triplet-triplet annihilation in the emission range shorter than 340 nm, which has not been explored well, is presented and the relevant physicochemical characteristics are elucidated. Investigations were carried out in several deaerated solvents using acridone and naphthalene derivatives as a sensitizer and emitter, respectively. Both upconversion quantum efficiency and sample photostability under continuous photoirradiation strongly depended on the solvent. The former dependence is governed by the solvent polarity, which affects the triplet energy level matching between the sensitizer and emitter because of the solvatochromism of the sensitizer. To elucidate the latter, first we investigated the photodegradation of samples without the emitter, which revealed that the sensitizer degradation rate is correlated with the difference between the frontier orbital energy levels of the sensitizer and solvent. Inclusion of the emitter effectively suppressed the degradation of the sensitizer, which is ascribed to fast quenching of the triplet sensitizer by the emitter and justifies the use of ketonic sensitizers for UV-UC in solvents. A theoretical model was developed to acquire insight into the observed temporal decays of the upconverted emission intensity under continuous photoirradiation. The theoretical curves generated by this model fitted the experimental decay curves well, which allowed the reaction rate between the emitter and solvent to be obtained. This rate was also correlated with the difference between the frontier orbital energy levels of the emitter and solvent. Finally, based on the acquired findings, general design guidelines for developing UV-UC samples were proposed.

Key Physicochemical Characteristics Influencing ADME Properties of Therapeutic Proteins.

Therapeutic proteins are a rapidly growing class of drugs in clinical settings. The pharmacokinetics (PK) of therapeutic proteins relies on their absorption, distribution, metabolism, and excretion (ADME) properties. Moreover, the ADME properties of therapeutic proteins are impacted by their physicochemical characteristics. Comprehensive evaluation of these characteristics and their impact on ADME properties are critical to successful drug development. This chapter summarizes all relevant physicochemical characteristics and their effect on ADME properties of therapeutic proteins.

Encapsulation of Antifouling Organic Biocides in Poly(lactic acid) Nanoparticles.

The scope of the current research was to assess the feasibility of encapsulating three commercial antifouling compounds, Irgarol 1051, Econea and Zinc pyrithione, in biodegradable poly(lactic acid) (PLA) nanoparticles. The emulsification–solvent evaporation technique was herein utilized to manufacture nanoparticles with a biocide:polymer ratio of 40%. The loaded nanoparticles were analyzed for their size and size distribution, zeta potential, encapsulation efficiency and thermal properties, while the relevant physicochemical characteristics were correlated to biocide–polymer system. In addition, the encapsulation process was scaled up and the prepared nanoparticles were dispersed in a water-based antifouling paint in order to examine the viability of incorporating nanoparticles in such coatings. Metallic specimens were coated with the nanoparticles-containing paint and examined regarding surface morphology.

Physico-Chemical and Antioxidant Characteristics in Fruits of Walnut (&lt;i&gt;Juglans regia L.&lt;/i&gt;) Genotypes from Inner Anatolia

Walnut fruits are used for their nutrition properties for a long time in Anatolia, where seed propagated walnuts are naturally found, as solitary individuals or dense populations. Some relevant physico-chemical and antioxidant characteristics of fruits were determined for fifteen promising walnut (Juglans regia L.) selections (named 'G-1' to 'G-15') propagated from seeds. The well-known Turkish walnut cultivar 'Sebin' was included in the analysis as a standard in order to make comparison with seed propagated genotypes. The average fruit weight and kernel ratios ranged from 7.43 to 12.61 g and 45.10 to 57.83% among the studied genotypes, respectively. The chemical analyses showed that protein, crude oil, ash, carbohydrate and dietary fiber contents of the analyzed walnut genotypes were between 11.09-18.16%, 55.38-65.15%, 1.61-2.08%, 12.01-17.89% and 2.90-4.12%, respectively. Total phenolic content was found between 1,107-1,876 mg GAE/100 g among the genotypes and most of them had higher phenolic content compared with cv. 'Sebin'. The total tocopherols content ranged from 30.0 to 44.4 mg/100 g of the extracted oil. The most common tocopherol in all samples was γ-tocopherol. The results obtained in the hereby study indicated that the seed propagated walnut trees can be very diverse and their nuts have a good potential for valuable sources of phytochemicals.

Vertical distribution of bacterial community is associated with the degree of soil organic matter decomposition in the active layer of moist acidic tundra.

The increasing temperature in Arctic tundra deepens the active layer, which is the upper layer of permafrost soil that experiences repeated thawing and freezing. The increasing of soil temperature and the deepening of active layer seem to affect soil microbial communities. Therefore, information on soil microbial communities at various soil depths is essential to understand their potential responses to climate change in the active layer soil. We investigated the community structure of soil bacteria in the active layer from moist acidic tundra in Council, Alaska. We also interpreted their relationship with some relevant soil physicochemical characteristics along soil depth with a fine scale (5 cm depth interval). The bacterial community structure was found to change along soil depth. The relative abundances of Acidobacteria, Gammaproteobacteria, Planctomycetes, and candidate phylum WPS-2 rapidly decreased with soil depth, while those of Bacteroidetes, Chloroflexi, Gemmatimonadetes, and candidate AD3 rapidly increased. A structural shift was also found in the soil bacterial communities around 20 cm depth, where two organic (upper Oi and lower Oa) horizons are subdivided. The quality and the decomposition degree of organic matter might have influenced the bacterial community structure. Besides the organic matter quality, the vertical distribution of bacterial communities was also found to be related to soil pH and total phosphorus content. This study showed the vertical change of bacterial community in the active layer with a fine scale resolution and the possible influence of the quality of soil organic matter on shaping bacterial community structure.

Agriculture biomass in India: Part 1. Estimation and characterization

Biomass residues or wastes generated in the agricultural sector represent a source of potentially sustainable feedstock for bio-refineries. The strategy toward such a bio-based economy will only succeed if enough biomass and adequate qualities can be provided not only to produce bioenergy but also to fulfil the food security and health requirements of the growing population. In India, the majority of the biomass generated come from agriculture sector. It is therefore important to have a reliable estimate of the biomass, biowaste and agro-residue generated to define policies for their valorization as well as identifying technologies which could be used for such purpose. Herein we present an assessment of the amounts and availability of biomass residues/wastes generated in the Indian agriculture sector for organized use as a biorefinery feedstock, for data collected up to the year 2010. A compilation of some relevant physicochemical characteristics of the residues is also included.

Mesoporous mordenites obtained by desilication: Mechanistic considerations and evaluation in catalytic oligomerization of pentene

Desilication of mordenite crystals previously enriched in silica by dealumination has been investigated in order to better understand the process of mesopore formation. Pentene oligomerization in the liquid phase in the presence of an alkane solvent has been used to evaluate the catalytic activity of the desilicated zeolite. Relevant physico-chemical characteristics such as texture, porosity, acidity and composition of zeolite samples desilicated at 80 °C in NaOH solutions at different base concentrations were analyzed quantitatively. The generation of mesoporosity is due to the hydrolysis and dissolution of the surface of the crystals, probably initiated by the formation of etch pits at low coordination atoms, followed by surface roughening, formation and growth of internal mesopores, fragmentation and, ultimately, by a complete dissolution of the crystal. Such a process which is similar to the one involved in the chemical weathering of rocks, results in a severe loss of crystalline material and of the strong acidity associated to it. The oligomerization catalyst prepared from desilicated mesoporous mordenite proved highly stable and selective for the production of C15–C30 oligomers from pentene.

Identification of relevant physicochemical characteristics for predicting fruit juices filterability

Cross-flow microfiltration has replaced conventional fining methods for clarifying fruit juices, resulting in the combination of clarification and preservation in one single continuous operation. However the performance of this process is limited by the fouling mechanism during the filtration operation, related to the fruit juice fouling propensity. The aim of this work was to study the possibility of predicting the fruit juices filterability, according to some of their intrinsic characteristics. Therefore, 9 different commercial orange juices were chemically and physicochemically characterized (17 characterization parameters) and laboratory scale filtration tests, in an agitated and pressurized filtration module, were carried out at constant transmembrane pressure (1.5bar). Fruit juices filterability was evaluated from the permeate flux evolution during the filtration operation. Partial Least Squares (PLS) method was particularly used for the analysis of relationship between the fruit juices filterability and the juice studied characteristics. PLS was initially performed using the whole set of predictor variables. The aim of this first analysis was to highlight the most important juice characteristics among the 17 studied ones; a simplified PLS model was performed using model-wise method and PLS–VIP method as important variable selection procedure. It was possible to predict satisfactorily (R2>0.9) fruit juices filterability according to only 5 physicochemical characteristics, reflecting the different phases of the studied juices (dry matter, total soluble solids, pH, conductivity, and surface area average diameter).

Physicochemical characterization of fruit quality traits in a German sour cherry collection

Several commercially relevant physicochemical fruit characteristics (fruit weight, fruit firmness, juice color intensity, soluble solid content, titratable acidity) were studied for three years during the research period 2005–2009 in 78 sour cherry genotypes of the Fruit genebank of the Julius Kühn-Institut in Dresden, Germany.A high phenotypic variability with significant differences between cultivars has been found for each of the fruit quality traits studied. Dependent on the trait, a certain number of cultivars were observed that showed lower or higher values than the commercially grown cultivars involved in this study. The favorable characteristics of a number of cultivars were consolidated by lower-year-by year variations in comparison to those of some commercial cultivars. The diversity of the physicochemical traits in the germplasm evaluated represents a basis for the selective choice of genotypes for commercial growing and breeding programs.

Recent toxicological investigations of metal or metal oxide nanoparticles in mammalian models in vitro and in vivo: DNA damaging potential, and relevant physicochemical characteristics

Concomitant with the increase in production and application of various nanomaterials, researches on their cytotoxic and genotoxic potential have become well established, as exposure to these nanoscaled materials may contribute to detrimental health effects. Positive indications of the damaging effects of nanoparticles on DNA are likely to be inconsistent in in vitro systems, and thus the implementation of in vivo investigations has been achieved. This review summarizes the current results, both in vitro and in vivo, of the genotoxic effects of potential metal or metal oxide nanoparticles, including the oxides of aluminium, iron, silica, titanium, and zinc, as well as silver, gold, cobalt, quantum dots, and so forth. They present indications of different types of DNA damage, ranging from chromosomal aberrations, through DNA strand breaks, oxidative DNA damage, to mutations. Their toxicological profiles are definitely associated with physicochemical characters, depending upon the characterization methods by which they are analyzed, in particular, microscopy techniques. Besides physicochemical properties, we also discuss significant parameters that may influence genotoxic response, including toxicity assays/endpoint tests, exposure duration and route of exposure, and experimental conditions. We describe advantages and disadvantages of particular characterization methods, as well as the appropriateness of methodologies for investigating physicochemical characters. Therefore, recommendations on particle characterization are further emphasized, to provide better understanding of genotoxic potential.

Recent developments in capillary and microchip electroseparations of peptides (2011–2013)

The review presents a comprehensive survey of recent developments and applications of capillary and microchip electroseparation methods (zone electrophoresis, ITP, IEF, affinity electrophoresis, EKC, and electrochromatography) for analysis, isolation, purification, and physicochemical and biochemical characterization of peptides. Advances in the investigation of electromigration properties of peptides, in the methodology of their analysis, including sample preseparation, preconcentration and derivatization, adsorption suppression and EOF control, as well as in detection of peptides, are presented. New developments in particular CE and CEC modes are reported and several types of their applications to peptide analysis are described: conventional qualitative and quantitative analysis, determination in complex (bio)matrices, monitoring of chemical and enzymatical reactions and physical changes, amino acid, sequence and chiral analysis, and peptide mapping of proteins. Some micropreparative peptide separations are shown and capabilities of CE and CEC techniques to provide relevant physicochemical characteristics of peptides are demonstrated.