DG Values Research Articles

Diffusion coefficient of solute in heterogeneous and macroporous hydrogels and its correlation with the effective crosslinking density

The diffusion coefficient, Dg, of a solute in hydrogels is a key parameter in their applications. Dg has been correlated with the volume fraction, φp, of polymer in gel. In this study, the effective crosslinking density, νe, was determined from the rubber network theory using compression tests, and was applied as a model parameter for the characterization of the polymer networks and gel structures. It was subsequently examined to estimate Dg for various types of gels, including heterogeneous and macroporous gels. The Dg values of NaCl and trisodium citrate were determined with a permeability test using the gel membrane. The diffusion of the solute in all the tested gels was accurately represented by both conventional (Dg/D0 = exp(-kφpn)) and novel (Dg/D0 = exp(-aνeb)) models.

Molecular Modeling Study of 2-Substituted Isoindoline Derivatives of a-Amino Acids as Inhibitors of Lipoxygenase by Docking Simulations

In this work two series of isoindolines 1(a-g) and 2(a-g) were evaluated as possible inhibitors of lipoxygenase (LOX) by docking studies, as well as for the antiinflammatories isoindolilamides 3-5 and ibuprofen 6, as part of a theoretical study to found dual LOX/ COX inhibitory activities. Therefore, dihydrodimethylbenzofurane 7, licofelone 8 and darbufelone 9 were also evaluated, which are wellknown as dual LOX/COX inhibitors and consequently, in this work they were used to identify their binding sites on the LOX and compared with those obtained from 1(a-g), 2(a-g) and 3 to 6 under study. Analysis of the results showed that all compounds under study could inhibit to the LOX, since they are binding in the same or close to the region as the compounds 7-9 taken as references. Several interactions of heteroatom of all compounds with the amino acid residues of binding sites of LOX were determined. The DG values were obtained for all the complexes (LOX-compound), among all the complexes, LOX-8 (-12.76 kcal/mol) resulted to be the most stable; and from the compounds under study, LOX-1f (-8.97 kcal/mol) resulted to be more stable than the other compounds tested. Whereas, theoretical dissociation constant values Kd (mM) were obtained. Among all compounds, 8 (0.000433 mM) showed more affinity to LOX; while from compounds under study, 1f (0.266 mM) exhibited more affinity to LOX. These results also show that compounds 1(a-g) and 2(a-g), and 3-6 could have a dual LOX/COX/ inhibition, as have been shown for 7-9 and from their similar docking study within the COX-1 and COX-2 previously reported.

CHARACTERISATION OF TLDS-200 AND OSLDS AT LOW X-RAY ENERGIES AND DETERMINATION OF EYE LENS DOSE, THYROID DOSE AND MEAN GLANDULAR DOSE DURING STANDARD MAMMOGRAPHY AND TOMOSYNTHESIS.

The objective of this study was to characterise thermoluminescent (TLDs) and optically stimulated luminescent dosimeters (OSLDs) at low X-ray energies and estimate the eye lens (DL), thyroid (DT) and mean glandular (DG) doses received during Full-Field Digital Mammography (FFDM) and Digital Breast Tomosynthesis (DBT). The dosimeters were characterised in mammography energies. DL, DT and DG were estimated in FFDM and DBT mode taping dosimeters on the skin of the thyroid gland and on the left eye lens of an Alderson phantom. Dosimeters were also placed on the top of a NORMI PAS phantom simulating a compressed breast. The accuracy, precision and lower limit of detection (LLD) for TLDs and OSLDs were 5 and 8%, 6 and 3%, and 38 and 11 μSv, respectively. The linearity of the kerma response had an R2 > 0.99 and energy dependence was lower than 40%. DT ranged from 0.40 to 2.87 μGy for FFDM and 1.27 to 5.99 μGy for DBT. DG was between 0.50 and 1.27 mGy for FFDM and 1.07 and 1.60 mGy for DBT. DL was below the LLD. Dosimeters showed good performance. DG values were lower than those found in the literature, whereas DT value agreed with references. Differences between DG and DT determined with OSLDs and TLDs were lower than 10% and 200%.

New inverse gas chromatographic methodology for studying mass transfer caused by the evaporation of volatile liquids

Physico-chemical quantities related to evaporation have been simply and directly calculated by a new methodology of reversed-flow inverse gas chromatography. The only demand is a preliminary determination of quantification coefficient(s), converting the signal to solute(s) molar or volume units. Time-dependent, kc(t) and overall mass transfer, kc, coefficients were determined for the evaporation of methanol at temperatures from 305 to 336 K, using two diffusion column lengths (10.0 and 40.5 cm) to evaluate the effect of the mass transfer route. Mass transfer coefficients indicate the endothermic nature of evaporation, while the longer diffusion route resulted in lower kc values. The precision in the determination of evaporation rates was high (98.3%). Time-resolved diffusion coefficients, Dg(t), were also estimated. The smaller diffusion route resulted in lower values due to the higher enrichment of the mobile phase in the solute vapors. In the case of the smaller diffusion route, the change of Dg(t) values increased from 0.1% to 0.8%, while in the longer it was less than 0.1%. The respective temperature exponent increased with the diffusion route length from 1.68 to 1.74. Removing the effect caused by the different lengths of diffusion routes, the activation energy corresponding to pure evaporation was equal to 35.2 kJ mol−1, rather close to the literature values for methanol’s vaporization enthalpy, indicating the reliability of the new methodology. Finally, the effect of mass transfer route was estimated to be 229 MJ mol−1 km−1, revealing the huge amounts of heat transfer accompanying evaporation at high altitudes.

Quality attributes of parboiled rice prepared with a parboiling process using a rotating sieve system

The aim of this study is to apply a rotating sieve system to the parboiling process for parboiled rice production. The parboiling time and rotation speed were the main production factors affecting the quality attributes of the parboiled rice, including the degree of starch gelatinization (DG), fissure percentage, head rice yield (HRY), white belly, and color. The results showed that the parboiling process with a rotating sieve can decrease the parboiling time required to provide an even quality of parboiled rice. The parboiling time for an even quality of parboiled rice was 5 min at rotation speeds of 10 and 15 rpm, while the parboiling time at a rotation speed of 5 rpm was 10 min. These times were shorter than that with a fixed sieve (15 min). Moreover, the parboiling process using a rotating sieve system provided better qualities of parboiled rice than that using the fixed sieve system, including higher DG and HRY and lower fissure and whiteness percentages. Additionally, the values of DG and HRY were increased with increasing parboiling time. In contrast, the fissure and whiteness percentages of the parboiled rice decreased. However, the quality of the parboiled rice was not dependent on the rotation speed.

Bioavailability Study of Maqui Berry Extract in Healthy Subjects.

Several health promoting effects have been reported for maqui berry, rich in anthocyanins. Direct effects of anthocyanins as well as bioactive metabolites might be involved. Within the study, bioavailability of a proprietary standardized maqui berry extract Delphinol® was investigated based on two selected anthocyanins (delphinidin-3-O-glucoside (DS) + cyanidin-3-O-sambubioside (CS)) and two breakdown products (protocatechuic acid (PCA) + gallic acid (GA)) after a single-dose supplementation in humans. Pharmacokinetic parameters were calculated from individual concentration time curves. In all 12 subjects a significant increase was noted in plasma values of DG and CS after intake of maqui berry extract. Maximum concentration of DG was observed after 1.0 ± 0.3 h and CS after 2.0 ± 1.1 h. Within 8 h, concentrations nearly returned to baseline levels. The results confirm a fast uptake and metabolism of the two selected key substances. Additionally, the phenolic acids GA and PCA were observed as breakdown products of anthocyanins. In summary, the study clearly confirms the bioavailability of maqui berry extract and its specific anthocyanin compounds and related breakdown products in healthy subjects.

Use of Artificial Neural Network for Modeling and Prediction of Reactive Red Dye Removal from Wastewater Using Banana Peels Bio-sorbent

Bio-sorption of red dye from aqueous solutions onto banana peels was investigated. Effects of initial pH, bio-sorbent dose, initial concentration, contact time, and temperature were studied and they found of 3, 0.4 g/100 mL, 50 mg/L, 100 min and 298 K respectively with removal efficiency of 93.44%. Artificial neural network was used for prediction of adsorption efficiency and its outputs showed a better fit than other traditional isotherm models. The negative values of DG� and DH� indicate that the bio-sorption of red dye was favored and exothermic. The sensitivity analysis signified that the pH was the most influential variable.

Development of Hybrid IgG-Aptamer Sandwich Immunoassay Platform for Aflatoxin B1 Detection and Its Evaluation Onto Various Field Samples.

The present study was aimed to develop a novel antibody-aptamer based hybrid detection strategy for specific and sensitive detection of aflatoxin B1 (AFB1) from contaminated food grains. The study comprises generation of ssDNA aptamers and anti-AFB1 IgG against AFB1 toxin. The generated bio-probes (aptamers and antibodies) were further characterized for their specificity and sensitivity using indirect ELISA. The generated aptamers namely AFB1a and AFB1b showed prominent reactivity and selectivity against AFB1 toxin. These aptamers were further characterized for their secondary structures and dG values were determined as −4.6 and −2.75 Kcal/mol, respectively. The detection limit (LOD) of AFB1a and anti-AFB1 IgG was determined as 5 and 10 ng/mL, respectively. The characterized aptamers and antibodies against AFB1 were used to develop the sandwich immunoassay. Anti AFB1 IgG was used as a capturing antibody whereas anti-AFB1a aptamer was used as its revealing partner in the assay. The limit of detection (LOD) of the immunoassay was determined to be 5 ng/mL of AFB1 standard toxin and showed no cross-reactivity with closely related mycotoxins. To assess the reliability of the developed method, several field samples contaminated with aflatoxin B1 was included in the study and results were validated with commercial AFB1-ELISA Kit. Additionally, the spiking studies were also carried out to demonstrate the consistency and dependability of the developed hybrid sandwich immunoassay wherein the toxins recovered were found to be ranging between 73 and 98.80% with the LOD at 5 ng/mL. In conclusion, the developed method may find the better utility in routine food testing laboratories for assessment of AFB1.

Role of plasma membrane surface charges in dictating the feasibility of membrane-nanoparticle interactions

Receptor-ligand (R-L) binding mediated interactions between the plasma membrane (PM) and a nanoparticle (NP) require the ligand-functionalized NPs to come to a distance of separation (DOS) of at least dRL (length of the R-L complex) from the receptor-bearing membranes. In this letter, we establish that the membrane surface charges and the surrounding ionic environment dictate whether or not the attainment of such a critical DOS is possible. The negatively charged membrane invariably induces a negative electrostatic potential at the NP surface, repelling the NP from the membrane. This is countered by the attractive influences of the thermal fluctuations and van der Waals (vdw) interactions that drive the NP close to the membrane. For a NP approaching the membrane from a distance, the ratio of the repulsive (electrostatic) and attractive (thermal and vdW) effects balances at a critical NP-membrane DOS of dg,c. For a given set of parameters, there can be two possible values of dg,c, namely, dg,c,1 and dg,c,2 with dg,c,1 ≫ dg,c,2. We establish that any R-L mediated NP-membrane interaction is possible only if dRL > dg,c,1. Therefore, our study proposes a design criterion for engineering ligands for a NP that will ensure the appropriate length of the R-L complex in order to ensure the successful membrane-NP interaction in the presence of a given electrostatic environment. Finally, we discuss the manner in which our theory can help designing ligand-grafted NPs for targeted drug delivery, design biomimetics NPs, and also explain various experimental results.

Montmorillonite Nanoparticles in Removal of Textile Dyes from Aqueous Solutions: Study of Kinetics and Thermodynamics

Dyeing wastewaters are one of the most common pollutants that cause many problems for public health and environment due to dermatitis and skin rashes, cancer production, mutagenesis, etc. Thus, treatment of these wastewaters is necessary. The purpose of this study was to investigate the efficiency of montmorillonite nanoparticles as an adsorbent in adsorption process of Reactive Yellow 15 (RY15) and Reactive Yellow 42 (RY42) dyes from aqueous solutions. In this study, montmorillonite nanoparticles were used to remove RY15 and RY42 dyes. The effect of different variables such as pH, contact time, dye concentration and adsorbent dosage was studied. Finally, the effect of process temperature and thermodynamic was studied. Also, pseudo-first and second orders of kinetics were studied. The results showed that 3 is the best pH for the removal of both dyes. As contact time increases to 15 minutes, adsorption capacity increases and then reaches an approximately constant value. Adsorption capacity was also increased with increased dye concentration. By changing the adsorbent dosage from 0.2 to 0.6 g/L, adsorption capacity for RY15 and RY42 was reduced from 142and 166 to 63 and 59 mg/g, respectively. The results also showed that both dyes had the highest correlation with pseudo-second-order kinetics. The results of analyzing the process thermodynamics and temperature showed that values of DH, DS and DG are negative for both dyes.

The Fractal Characteristics of Drainage Networks and Erosion Evolution Stages of Ten Kongduis in the Upper Reaches of the Yellow River, China

Abstract: The fractal characteristics of drainage in the ten kongduis of the upper Yellow River were obtained using the box counting dimension, and the evolution stages of the watershed topography were defined by different ranges of the fractal dimensions of river networks (Dg). The results show that the fractal scaleless range of the Maobula River is 20–370 m based on a combination of artificial judgment, correlation coefficient test and fitting error. Other kongduis show good fractal characteristics in this fractal scaleless range as well. The box counting dimension can be used as a quantitative index of watershed topography fractal characteristics. The fractal dimension of stream networks is independent of the threshold contributing area used for extracting the drainage networks from the DEM. The values of Dg in the upper ten kongduis are in the range of 1.08–1.14. Both the runoff yield and the sediment yield are positively and linearly related with Dg. The positive relation between the sediment yield ...

Immuno Affinity SELEX for Simple, Rapid, and Cost-Effective Aptamer Enrichment and Identification against Aflatoxin B1.

Aflatoxins are naturally occurring mycotoxins that contaminate food and agro commodities, leading to acute and chronic health conditions in human and animals. In the present work, an attempt was made to generate high-affinity single stranded DNA aptamers that specifically bind to Aflatoxin B1 (AFB1) by a modified Systemic Evolution of Ligands by Exponential Enrichment (SELEX) procedure with the aid of Immunoaffinity columns. Ten rounds of SELEX and alternating three counter SELEX rounds with a cocktail of related and other mycotoxins were performed to enhance the specificity. Resultant 105 aptamers were clustered into 12 groups according to their primary sequence homology. Candidates with lowest Gibbs free energy (dG value) and unique stem loop structures were selected for further characterization. Aptamers, AFLA5, AFLA53, and AFLA71 exhibiting lower Kd values (50.45 ± 11.06, 48.29 ± 9.45, and 85.02 ± 25.74 nM) were chosen for development of ELONA and determination of purification ability of toxin. The detection limit (LOD) of AFLA5 and AFLA71 was 20 and 40 ng/ml, respectively. HPLC analysis implied that selected aptamers were able to recover and quantify 82.2 to 96.21% (LOQ – 53.74 ng) and 78.3 to 94.22% (LOQ – 66.75 ng) of AFB1 from spiked corn samples, respectively. These findings indicate, immunoaffinity based SELEX can pave an alternative approach to screen aptamers against mycotoxin detection and purification.

THERMODYNAMIC PROPERTIES AND CHARACTERIZATIONS OF CHITOSAN NANO-PARTICLES CORROSION INHIBITION ON THE SURFACE OF MILD STEELIN PEAT WATER MEDIA

The thermodynamic properties and characterizations of corrosion inhibition of chitosan nano-particles on the surface of mild steel in peat water media had been studied using weight loss method at temperatures of 30 - 50 <sup>o</sup>C. Steel surfaces were characterized by FT-IR spectra and SEM-EDS morphology photos. The research found that the value of DG<sup>o </sup>approaching -40 kJmol<sup>-</sup><sup>1</sup>. The negative value of Gibbs free energy shows that the adsorption of inhibitor molecules on the surface of mild steel was achemisorption and it occurred spontaneously. Meanwhile, the values of DH<sup>o </sup>is also negative confirming that the adsoprtion of inhibitor molecules is an exothermic process. The value of DS<sup>o </sup>obtained is positive, it indicates hat the inhibitor molecules were adsorbed spontaneously on the mild steel surface. The analysis on mild steel surfaces hows that the nano-particle chitosan was adsorbed on the steel surface to form the complex compounds.

THERMODYNAMIC PROPERTIES AND CHARACTERIZATIONS OF CHITOSAN NANO-PARTICLES CORROSION INHIBITION ON THE SURFACE OF MILD STEELIN PEAT WATER MEDIA

The thermodynamic properties and characterizations of corrosion inhibition of chitosan nano-particles on the surface of mild steel in peat water media had been studied using weight loss method at temperatures of 30 - 50 <sup>o</sup>C. Steel surfaces were characterized by FT-IR spectra and SEM-EDS morphology photos. The research found that the value of DG<sup>o </sup>approaching -40 kJmol<sup>-</sup><sup>1</sup>. The negative value of Gibbs free energy shows that the adsorption of inhibitor molecules on the surface of mild steel was achemisorption and it occurred spontaneously. Meanwhile, the values of DH<sup>o </sup>is also negative confirming that the adsoprtion of inhibitor molecules is an exothermic process. The value of DS<sup>o </sup>obtained is positive, it indicates hat the inhibitor molecules were adsorbed spontaneously on the mild steel surface. The analysis on mild steel surfaces hows that the nano-particle chitosan was adsorbed on the steel surface to form the complex compounds.

THERMODYNAMIC PROPERTIES AND CHARACTERIZATIONS OF CHITOSANNANO-PARTICLES CORROSION INHIBITION ON THE SURFACE OF MILD STEELIN PEAT WATER MEDIA

<p>The thermodynamic properties and characterizations of corrosion inhibition of chitosan nano-particles on the surface of mild steel in peat water media had been studied using weight loss method at temperatures of 30 - 50 <sup>o</sup>C. Steel surfaces were characterized by FT-IR spectra and SEM-EDS morphology photos. The research found that the value of DG<sup>o </sup>approaching -40 kJmol<sup>-</sup><sup>1</sup>. The negative value of Gibbs free energy shows that the adsorption of inhibitor molecules on the surface of mild steel was achemisorption and it occurred spontaneously. Meanwhile, the values of DH<sup>o </sup>is also negative confirming that the adsoprtion of inhibitor molecules is an exothermic process. The value of DS<sup>o </sup>obtained is positive, it indicates hat the inhibitor molecules were adsorbed spontaneously on the mild steel surface. The analysis on mild steel surfaces hows that the nano-particle chitosan was adsorbed on the steel surface to form the complex compounds. </p>

Thermophysical properties of laboratory-prepared corn/wheat dried distillers grains and dried distillers solubles dehydrated with superheated steam and hot air

ABSTRACTThe objective of this study was to dry–wet distillers grains and centrifuged solubles and to examine the effect of two different drying media, superheated steam and hot air, at different drying temperatures (110, 130, and 160°C), moisture contents (5–30% wb), and percentages of solubles’ presence (0 or 100%) on some thermophysical properties of laboratory-prepared corn/wheat dried distillers co-products, including geometric mean diameter (dg), particle density (ρp), bulk density (ρb), bulk porosity (ϵb), specific heat (C), effective thermal diffusivity (αeff), and bulk thermal conductivity (λb). The values of dg of corn/wheat dried distillers co-products ranged from 0.358 ± 0.001 to 0.449 ± 0.001 mm. Experimental values of ρp, ρb, and ϵb varied from 1171 ± 6 to 1269 ± 3 kg m−3, from 359 ± 7 to 605 ± 5 kg m−3, and from 0.54 ± 0.01 to 0.71 ± 0.01 kg m−3, respectively. The values of αeff were between 0.58 × 10−7 and 0.93 × 10−7 m2 s−1. The calculated values of C ranged from 1887 ± 11 to 2599 ± 19 J kg−1 K−1, and the values of λb of corn/wheat dried distillers co-products ranged from 0.06 ± 0.01 to 0.09 ± 0.01 W m−1 K−1. Multiple linear regression prediction models were developed to predict the changes in dg, ρp, ρb, ϵb, C, αeff, and λb of laboratory-prepared corn/wheat dried distillers co-products with different operational factors.

Investigation of derivatized schiff base ligands of 1,2,4-triazole amine and their oxovanadium(IV) complexes: Synthesis, structure, DNA binding, alkaline phosphatase inhibition, biological screening, and insulin mimetic properties

A series of novel azomethine precursors were derivatized by the condensation of 4H-1,2,4-triazole-4-amine with salicylaldehyde (HL1) (saltrz), 2,3-dihydroxybenzaldehyde (HL2) (dhtrz), 2-hydroxy-1-naphthaldehyde (HL3) (ndtrz) and 5-chloro-2-hydroxybenzaldehyde (HL4) (cltrz). Subsequently, oxovanadium(IV) complexes of the type [VO(saltrz)2] (1), [VO(dhtrz)2] (2), [VO(ndtrz)2] (3), and [VO(cltrz)2] (4) were synthesized by the reactions of vanadyl(V) isopropoxide [VO(OCHMe2)3] with the ligands HL1–HL4. The synthesized compounds were characterized by the melting point method, elemental analysis, FT-IR and 1H and 13C NMR spectroscopies, the molar susceptibility and conductivity methods, and by the thermogravimetry. Ligands HL3 and HL4 were also characterized by single crystal analysis. The binding modes of SS-DNA with the compounds were confirmed by the hypochromism and red/blue shift of the UV-Vis spectra. The negative DG values of the compound-DNA adducts show that the binding is a spontaneous process. The complexes were found to be persuasive inhibitors of enzyme alkaline phosphatase (ALP). The in vitro screening of the antimicrobial activities of the synthesized compounds revealed significantly enhanced activities of oxovanadium(IV) complexes as compared to their respective ligands. The promising results were obtained in studying the insulin mimetic of the synthesized compounds.

Dual-energy contrast-enhanced digital mammography: patient radiation dose estimation using a Monte Carlo code.

Mammography is a standard procedure that facilitates breast cancer detection. Initial results of contrast-enhanced digital mammography (CEDM) are promising. The purpose of this study is to assess the CEDM radiation dose using a Monte Carlo code. EGSnrc MC code was used to simulate the interaction of photons with matter and estimate the glandular dose (Dg). A voxel female human phantom with a 2-8-cm breast thickness range and a breast glandular composition of 50 % was applied. Dg values ranged between 0.96 and 1.45 mGy (low and high energy). Dg values for a breast thickness of 5.0 cm and a glandular fraction of 50 % for craniocaudal and mediolateral oblique view were 1.12 (low energy image contribution is 0.98 mGy) and 1.07 (low energy image contribution is 0.95 mGy), respectively. The low kV part of CEDM is the main contributor to total glandular breast dose.

Mean glandular dose in six digital mammography services in Santiago, Chile: preliminary reference levels.

The purpose of this paper was to estimate mean glandular dose levels (DG) in six digital mammography systems in Santiago, Chile, and to propose preliminary reference levels to execute mammography in Chile. The study was carried out assessing two direct digital systems and four computer-based radiography (CR) systems. Estimates of DG were calculated for different thicknesses of polymethyl methacrylate according to the quality control protocol in digital mammography of the Spanish Society of Medical Physics and NHSBSP Equipment Report 0604 Version 3. DG values ranged between 0.64 and 7.26 mGy for a range of 20- to 70-mm thickness, respectively. Thirty-six per cent of DG was higher than the acceptable dose level and 100 % of DG was higher than the desirable level. It is therefore necessary to optimise doses. The initial proposal to establish dose reference levels for DG would range between 0.90 and 6.40 mGy for a thickness range of 20 to 70 mm.

Valuation of Distributed Solar: A Qualitative View

A critical evaluation of the arguments used by solar DG advocates shows that those arguments may often overvalue solar DG. It is time to reassess the value of solar DG from production to dispatch and to calibrate our pricing policies to make certain that our efforts are equitable and carrying us in the right direction.