STUDY ON SORPTION ISOTHERMS OF SHRIMP BEADS

ABSTRACT

Sorption isotherms of shrimp heads ( adsorption and desorption ) were analyzed by the microclimate method as temperatures of 30, 45 and 60°C and conditions for shrimp heads conservation by drying were determined. Equilibrium time was reduced from normally 2–3 weeks to only 5–8 days by employing sulfuric acid at different concentrations and vacuum. The results were adjusted by Henderson and G.A.B. models and correlation coefficients were up to 0.9900 for the last model.     

THE DEHYDRATION OF GARLIC. 1.DESORPTION ISOTHERMS AND MODELLING OF DRYING KINETICS

Abstract

Desorption isotherms for 1 mm thick garlic slices were determined at between 25 and 50°C and satisfactorily fitted with the G.A.B. equation. The kinetics of drying of slices of thickness 1.5 - 5.0 mm were determined at between 40 and 60°C using an air flow rate of 2.5 m-s^?, and the conditions affording a high-quality product m the shortest time were identified. After establishing how the effective diffusion coefficient of the garlic slices varied with their moisture content during drying, a diffusional model accounting for these variations was developed and satisfactorily fitted to the experimental kinetic data.     

Effect of the interfacial area measurement parameters on the push-out strength between fiber post and dentin

PurposeTo verify the influence of different instruments and operators on the bonding interfacial area and on the push-out bond strength values.Material and methodsFifteen anterior human teeth (n=15) were selected, cleaned and standardized to 15 mm length. Root canals were prepared in 12 mm and the fiber posts were cemented using the RelyX U-100 cement. Three slices were obtained per tooth (N=45) and submitted to the push-out bond strength test. The bonding interfacial area (mm²) of each specimen was calculated based on the disc slice dimensions: coronal and apical diameter and height. The bonding area of each specimen was used to calculate the bond strength (Mpa). The dimensions were analyzed by different operators, using two instruments: G1 – Operator A with a digital caliper; G2 – Operator A with a stereomicroscope; G3 – Operator B with a digital caliper; G4 – Operator B with a digital stereomicroscope; G5 – Operator C with a digital caliper; G6 – Operator C with a stereomicroscope. The mean area was submitted to inter-operator and intra-operator analyses, while the mean area and mean of bond strength were submitted to the 2-way ANOVA with repeated measures and the Tukey test (α=0.05).ResultsThe inter-operator kappa was 0.83 to the digital caliper and 0.91 to the stereomicroscope, while the intra-operator kappa was 0.76. The operator and the measurement instrument influenced the interfacial bonding area (p=0.000 and p=0.001) and the push-out bond strength values (p=0.000 and p=0.000, respectively) of the disc slices.ConclusionThe final push-out bond strength values are influenced by the measuring instrument and by the measurer operator.     

MODELLING OF DESORPTION ISOTHERMS OF CHESTNUT: INFLUENCE OF TEMPERATURE AND EVALUATION OF ISOSTERIC HEATS

The desorption isotherms of chestnuts (Castanea sativa Mill) were determined at 278, 293, 303, 313, and 323K by a gravimetric technique. The range of water activity was from 0.08 at 0.91. The sorption isotherms were of the type II according to Brunauer's classification. The effect of the temperature shows a cross over of the desorption isotherms at water activity 0.6. The experimental data are fitted with several models (Oswin, Smith, Henderson, Halsey, and G.A.B.). Oswin and G.A.B. models gave the best fittings. Particularly, with G.A.B. model parameters some interesting information as monolayer moisture content, heat of sorption of the first and nth layer adsorbed and net isosteric heat were obtained.     

DRYING CHARACTERISTICS OF THE HAZELNUT

Abstract

Equilibrium moisture content isotherms for Spanish hazelnut (Corylus avellana L.) at different temperatures (30°C-80°C) were determined using static gravimetric method. Thin layer drying experiments were done with forced air circulation and were conducted with different operating conditions to determine the drying characteristics of hazelnuts. The effect of air temperature (30°C-70°C), air velocity (0.5 m/s - 2 m/s) and drying bed loading density (50 kg/m² - 150 kg/m²) on drying of unshelled and shelled hazelnuts was studied. Six mathematical models were used to fit the experimental equilibrium moisture content data, from which the G.A.B. model was found to give the best fit. Diffusion coefficients were determined by fitting experimental thin-layer drying curves to the Fick's diffusion model. Variation of the effective diffusion coefficient with temperature was of the Arrhenius type. The Page equation was found to describe adequately the thin layer drying of hazelnut. Page equation drying parameters k and n were correlated with air temperature and relative humidity.     

DOUBLE FJORD MOTIF IN OVERCROWDED LARGE POLYCYCLIC AROMATIC HYDROCARBONS: THE CONFORMATIONAL SPACE OF HEXABENZO[a,cd,f,j,lm,o]PERYLENE

The overcrowded large polycyclic aromatic hydrocarbon (LPAH) hexabenzo[a,cd,f,j,lm,o]perylene (HBP) was subjected to a theoretical study. The ab-initio Hartree-Fock (HF) and the density functional theory (DFT) B3LYP methods were employed to calculate energies and geometries of the stationary point conformations of HBP. The global minimum was found to be the twisted t-D ₂ ; the local minimum anti-folded a-C _2h was 20.5 kJ/mol higher in energy (B3LYP/6-31G(d)). Thus, only t-D ₂ -HBP exists at room temperature in solution. The enantiomerization of HBP proceeds via a pathway that connects the chiral t-D ₂ to the achiral a-C _2h through a chiral twisted-folded transition state, tf-C ₁ . The energy barrier for enantiomerization was 134.4 kJ/mol. The central benzene ring F of t -D ₂ is highly distorted from planarity (torsion angles of 15.4° and ?30.5°), and has a remarkable resemblance to the twist angle of the central ene in the parent BAE bifluorenylidene (32°). Yet, nucleus-independent chemical shift (NICS) values, calculated at GIAO-B3LYP/6-31G(d)//B3LYP/6-31G(d) and the almost equal bond lengths (ca. 142 pm) of the central ring are indicative of the aromatic character of this ring. The NICS values are also indicative of the aromatic character of the peripheral rings and the central rings of the two minima and the transition state, consistent with the Clar picture.     

Synthesis,Structural Characterization,Spectroscopic Properties,and Theoretical Investigations of Aminoacridine Derivatives

Synthesis of four N-(heterocyclic)-9-aminoacridine derivatives was investigated. The synthesized compounds, N-thiazolyl-9-aminoacridine (AC1), N-(1,3,4-thiadiazolyl)-9-aminoacridine (AC2), N-(5-methyl-1,3,4-thiadiazolyl)-9-aminoacridine (AC3), and N-(5-phenyl-1,3,4-thiadiazolyl)-9-aminoacridine (AC4) were characterized by FT-IR, ¹H NMR, mass-spectral, and elemental analysis. Amine-imine tautomerism was suggested by density functional theory (DFT) calculations. The optimized structures were obtained using B3LYP/6–311++G(d,p) level of theory. The UV–Vis absorption spectra were measured in various organic solvents. The synthesized compounds AC1–AC4 exhibit absorption spectra characteristic of typical donor–acceptor compounds. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) analysis have been used to explain the internal charge transfer (ICT) phenomena within the molecules. Also, simulated UV spectra were calculated using TD-DFT (B3LYP/6–311++G(d,p) and the results were compared with the experimental values.     

Antimicrobial activity,effects on Streptococcus mutans biofilm and interfacial bonding of adhesive systems with and without antibacterial agent

ObjectivesThis study evaluated the antimicrobial activity (by agar disk diffusion test, AD), viability of S. mutans biofilm (VB), and effect on resin-dentin interface (RDI) of six adhesive systems.MethodsThree adhesives containing antibacterial components (Gluma 2Bond (G2B)/glutaraldehyde, Clearfil SE Protect (CSP)/MDPB and Peak Universal Bond (PUB)/chlorhexidine) and the corresponding adhesives with similar composition, but without antibacterial agents (Gluma Comfort Bond, GCB; Clearfil SE Bond, CSB and Peak LC Bond, PLB) were evaluated. AD was determined measuring the extent of halo formation following application of adhesives and control groups (light cured or not) to cultures of four strict anaerobic and four facultative bacteria. For VB, a UA159 biofilm was grown on adhesive-coated hydroxyapatite discs for five days, collected and processed to count the number of viable cells. For RDI analysis, adhesives were applied according to manufacturers' recommendations and teeth were restored with resin composite, sectioned to obtain bonded slices and visualized by SEM.ResultsAn inhibition halo was observed for G2B (strict anaerobic/light cured and not light cured), CSP (strict anaerobic and facultative/light cured and not light cured) and PUB (strict anaerobic and facultative/not light cured). PUB when light cured produced an inhibition halo on L. casei and S. mutans only. G2B and CSP significantly reduced the viability of S. mutans. Adhesives containing antimicrobial compounds had no detectable effect on RDI.ConclusionThe MDPB-containing bonding agent showed better results of inhibition for all oral pathogens tested and a decrease of viability of Streptococcus mutans biofilm, among the adhesives tested.     

Regioselective synthesis of new 2,5,6-trisubstituted 5,6-dihydro-2H-pyrazolo[3,4-d]thiazoles from 5-dimethylaminoethylene-thaozolidin-4-thiones

Thiazolidin-4-ones assembled through one-pot three-component (carbonyl compound, amine and ethyl mercaptoacetate) reactions in the presence of dicyclohexyl carbodiimide, on simultaneous treatment with dimethyl formamide dimethylacetal and Lawesson's reagent furnished 5-dimethylaminomethylene thiazolidin-4-thiones. These thiones on condensation with hydrazine derivatives afforded 2,5,6-trisubstituted-5,6-dihydro-2H-pyrazolo[3,4-d]thiazoles 4 and not their possible 1,5,6-trisubstituted regioisomers 5. Results of single-crystal X-ray diffraction studies of thiazolidin-4-one 1b have been reported. The structures of all the synthesized compounds were established by spectral data. DFT studies on regioisomers were carried out using B3LYP with the 6-31G** basis set and carbon NMR shifts of 4 show good correlation with experimental values.     

Spreading Pressure-Water Activity and Moisture Relationships in Starchy Materials

ABSTRACT

The spreading pressure values have been calculated by integration of the Gibbs equation using G.A.B. isotherm for different cereal grains and starchy materials. This procedure gives an useful analytic solution the ibtegral avoiding inherent mathematicai instability at very low water activity. It was found a non linear relationship between spreading pressure and water activity being this function weakly dependent on products and temperature. On the other hand a nearly linear relationship was observed between spreading pressure and moisture in the moisture range 0.0–0.15 ( dry basis).     

Synthesis of Optically Active Dendrimers Having Chiral Bisphosphine as a Core

Summary First and second generation chiral dendrimers P-1G1, P-2G1, P-1G2 and P-2G2 containing chiral bisphosphine as a core were synthesized via a reaction of chiral bisphosphine compound (S,S)-1 with benzyl ether dendrons. This is the first example of chiral dendrimers containing chiral phosphorus atoms. To investigate the effect of chiral phosphorus atoms on their conformations, optically inactive dendrimer P′-2G1 was synthesized as well using optically inactive initiator 1′ which was the mixture of rac-1 ((S,S)-1 and (R,R)-1) and meso-1. Their structures were characterized by ¹H, ¹³C, ³¹P NMR, and HRMS. According to CD measurement, optically active dendrimers exhibited the Cotton effect induced by the chirality of phosphorus atoms, while optically inactive dendrimer P′-2G1 showed no Cotton effect.     

Chemistry of <Emphasis Type="Italic">Glossodoris</Emphasis> Nudibranchs: Specific Occurrence of 12-Keto Scalaranes

With the aim of establishing whether the oxidation of the tricyclic carbon skeleton of scalaradial (1) is specific to Glossodoris mollusks, the chemical investigation of specimens of Glossodoris pallida from two distinct geographical areas (China and Guam) and of Glossodoris vespa and Glossodoris averni from Eastern Australia was performed. 12-Deacetoxy-12-oxo-scalaradial (4), recently reported from another Glossodoris nudibranch, was the main metabolite of G. pallida from China, G. vespa, and G. averni. A series of scalarane compounds 3 and 5–11, including the unprecedented 12,16-deacetoxy-12-oxo-scalarafuran 5, was isolated from the mollusks. Interestingly, a population of G. pallida from Guam displayed a different scalarane pattern that was characterized by scalaradial (1), deacetyl scalaradial (2), and deoxoscalarin (3), thus confirming previous reports. The specific occurrence of 12-keto-derivatives in some nudibranchs of the genus Glossodoris is discussed.     

MODELLING OF SORPTION ISOTHERMS OF DRIED VEGETABLE WASTES FROM WHOLESALE MARKET

The moisture sorption isotherms of dried vegetable wastes (based on green leaves and fruits) from wholesale market were determined at 25, 40, 60 and 90°C by the static gravimetric method. Experimental data were fit by using several mathematical models. The G.A.B. and the Halsey model gave the minimum mean square error. G.A.B. parameters were related with temperature by Arrhenius expressions.     

Separation of five bioactive compounds from Glycyrrhiza uralensis Fisch using a general three-liquid-phase flotation followed by preparative high-performance liquid chromatography

ABSTRACT

Glycyrrhiza uralensis

Fisch is homologous medicine for food plant and health-protective affection in the human body system. To further understand the functions of G. uralensis Fisch, separation of the bioactive compounds from this natural product is very important. A general three-liquid-phase flotation (TLPF) technique was established to separate and concentrate five bioactive compounds from G. uralensis Fisch. The three-liquid-phase system, pH of initial aqueous phase, (NH₄)₂SO₄ concentration, nitrogen flow rate, and flotation time were investigated. The flotation efficiency of liquiritin apioside, liquiritin, and glycyrrhizic acid in the middle phase and semilicoisoflavone B and licoisoflavone B in the upper phase could reach 91.24%, 94.23%, 88.04%, 94.67%, and 96.44%, respectively. Furthermore, the established TLPF was used for separation of four kinds of anthraquinones from Cassiae Semen. The results showed that TLPF is feasible for separating the compounds with quite a different polarity from natural products.     

SYNERGISTIC SOLVENT EXTRACTION OF TRIVALENT LANTHANIDES AND ACTINIDE BY MIXTURES OF 1-PHENYL-3-METHYL-4-BENZOYL-PYRA2ALONE-5 AND NEUTRAL OXO-DONORS

ABSTRACT

The synergistic solvent extraction of trivalent lanthanides such as La, Eu and Lu and a trivalent actinide, Am, has been studied with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazalone-5 (HPMBP) and bis(2-ethylhexyl) sulphoxide (B2EHSO) or octyl(phenyl)-N,N-di isobutylcarbamoylmethylphosphine oxide (CMPO) in xylene. The extraction data have been analysed by both graphical and theoretical methods by taking into account aqueous phase speciation and all plausible complexes extracted into the organic phase. With HPMBP alone all the trivalent metal ions form M(PMBP)₃.HPMBP type self adducts. With B2EHSO as a neutral donor, the synergistic adduct species are M(PMBP)₃.B2EHSO and M(PMBP)₃.2 B2EHSO (where M = La, Eu, Lu and Am), whereas with CMPO as a neutral donor the only complex extracted into the organic phase is M(PMBP)₃.CMPO. The synergistic extraction constants of the above species which were deduced by non-linear regression analysis are found to increase monotonically with decreasing ionic radii of these metal ions.     

BEHAVIOR OF EUCALYPTUS GLOBULUS LIGNIN DURING KRAFT PULPING. I. ANALYSIS BY CHEMICAL DEGRADATION METHODS

ABSTRACT

Eucalyptus globulus wood was subjected to kraft pulping, reaching different extents of delignification. The residual and dissolved lignins were isolated by soft acidolysis and acidic precipitation, respectively, and submitted to analysis of residual sugars and methoxyl groups, as well as to analysis by nitrobenzene and permanganate oxidation and thioacidolysis. Results from both residual and dissolved lignins analyses indicated that in the initial phase of pulping there is a preferential removal of lignin enriched in guaiacylpropane (G) and p-hydroxyphenylpropane (H) units, which is highly condensed and bonded with polysaccharides, predominantly with xylan. During the bulk and residual phases of pulping, lignin enriched in syringylpropane (S) units is progressively removed, leading to the increase of S/G ratio of black liquor lignin. After a purification step of dissolved lignins, two fractions with distinct levels of carbohydrates and with different structural features were obtained. The overall results were interpreted in terms of the topochemistry of the kraft pulping process.     

Burning Characteristics and Sensitivity Characteristics of Some Guanidinium 1,5′‐bis‐1H‐Tetrazolate/Metal Oxide Mixtures as Candidate Gas Generating Agent

Burning characteristics and sensitivity characteristics of some stoichiometric ratio guanidinium 1,5′‐bis‐1H‐tetrazolate (G15B)/metal oxide mixtures were examined. The linear burning rates of the G15B/CuO mixture were higher compared to other G15B/metal oxide mixtures and 5‐amino‐1H‐tetrazole(5‐ATZ)/Sr(NO₃)₂ mixture, although the average rate of pressure rise during the closed vessel test was lower compared to 5‐ATZ/Sr(NO₃)₂ mixture. The temperature rise for both G15B/CuO and G15B/MnO₂ mixtures was considerably lower than that of 5‐ATZ/Sr(NO₃)₂ mixture. G15B/Fe₂O₃ mixture was the most insensitive among G15B/metal oxide mixtures during the drop hammer test, while G15B/CuO mixture was the second most insensitive. All G15B/metal oxide mixtures were insensitive against friction and electric spark discharge (ESD). Four seconds ignition temperature for G15B/CuO mixture was over 100 K lower than that of 5‐ATZ/Sr(NO₃)₂ mixture, but the apparent activation energy for ignition was higher. Among the G15B/metal oxide mixtures studied, G15B/CuO mixture showed the fastest burning rate, while it showed a relatively low temperature rise and low sensitivity. G15B/ZnO did not burn at all.     

Study of Rhodamine B Retention by Polyurethane Foam from Aqueous Medium in Presence of Sodium Dodecylsulfate

Abstract

This work reports a study about the adsorption of Rhodamine B (RB) by unloaded polyether type polyurethane foam (PUF) in a medium containing sodium dodecylsulfate (SDS). The adsorption process was based on the formation of an ionic-pair between RB and SDS, which presented high affinity by PUF. Adsorption was characterized in relation to equilibrium, kinetic, and thermodynamic aspects and the results obtained showed that the ratio between the SDS and RB concentrations played an important role on the adsorption efficiency. A maximum adsorption capacity of 6.85 × 10^?6 mol RB g^?1 was observed at established experimental conditions. The adsorption process was spontaneous (negative ΔG) and presented an endothermic characteristic (positive ΔH). Also, its rate was regulated by an intraparticle diffusion process. Sequential extraction experiments were carried out by changing PUF plugs in 30 and 60 min time intervals, resulting in removal rates higher than 95%.     

Biotin Transport-Targeting Polysaccharide-Modified PAMAM G3 Dendrimer as System Delivering α-Mangostin into Cancer Cells and C. elegans Worms

The natural xanthone α-mangostin (αM) exhibits a wide range of pharmacological activities, including antineoplastic and anti-nematode properties, but low water solubility and poor selectivity of the drug prevent its potential clinical use. Therefore, the targeted third-generation poly(amidoamine) dendrimer (PAMAM G3) delivery system was proposed, based on hyperbranched polymer showing good solubility, high biocompatibility and low immunogenicity. A multifunctional nanocarrier was prepared by attaching αM to the surface amine groups of dendrimer via amide bond in the ratio 5 (G3^2B12gh5M) or 17 (G3^2B10gh17M) residues per one dendrimer molecule. Twelve or ten remaining amine groups were modified by conjugation with D-glucoheptono-1,4-lactone (gh) to block the amine groups, and two biotin (B) residues as targeting moieties. The biological activity of the obtained conjugates was studied in vitro on glioma U-118 MG and squamous cell carcinoma SCC-15 cancer cells compared to normal fibroblasts (BJ), and in vivo on a model organism Caenorhabditis elegans. Dendrimer vehicle G3^2B12gh at concentrations up to 20 µM showed no anti-proliferative effect against tested cell lines, with a feeble cytotoxicity of the highest concentration seen only with SCC-15 cells. The attachment of αM to the vehicle significantly increased cytotoxic effect of the drug, even by 4- and 25-fold for G3^2B12gh5M and G3^2B10gh17M, respectively. A stronger inhibition of cells viability and influence on other metabolic parameters (proliferation, adhesion, ATP level and Caspase-3/7 activity) was observed for G3^2B10gh17M than for G3^2B12gh5M. Both bioconjugates were internalized efficiently into the cells. Similarly, the attachment of αM to the dendrimer vehicle increased its toxicity for C. elegans. Thus, the proposed α-mangostin delivery system allowed the drug to be more effective in the dendrimer-bound as compared to free state against both cultured the cancer cells and model organism, suggesting that this treatment is promising for anticancer as well as anti-nematode chemotherapy.