Static and dynamic heterogeneities in irreversible gels and colloidal gelation

We compare the slow dynamics of irreversible gels, colloidal gels, glasses and spin glasses by analyzing the behavior of the so called non-linear dynamical susceptibility, a quantity usually introduced to quantitatively characterize the dynamical heterogeneities. In glasses this quantity typically grows with the time, reaches a maximum and then decreases at large time, due to the transient nature of dynamical heterogeneities and to the absence of a diverging static correlation length. We have recently shown that in irreversible gels the dynamical susceptibility is instead an increasing function of the time, as in the case of spin glasses, and tends asymptotically to the mean cluster size. On the basis of molecular dynamics simulations, we here show that in colloidal gelation where clusters are not permanent, at very low temperature and volume fractions, i.e. when the lifetime of the bonds is much larger than the structural relaxation time, the non-linear susceptibility has a behavior similar to the one of the irreversible gel, followed, at higher volume fractions, by a crossover towards the behavior of glass forming liquids.Comment: 9 pages, 3 figure

Chemical Studies on the Removal of Iron from Crude Phosphoric Acid Using an Organosilicon Compound

A new adsorbent has been developed to reduce the concentration of iron in crude Egyptian phosphoric acid. This adsorbent has been formed by the treatment of silicate compound derived from clay mineral with π organic acceptor ligand to carry out the exchange of ions as well as complexation with iron. Several parameters (shaking time, temperature, sorbent mass, and batch factor) have been studied. The adsorption of iron from crude phosphoric acid was investigated. The various methods to characterize the adsorption of iron on organosilicon compound (OSC) were collectively evaluated in this study. According to the Langmiur model, the maximum monomolecular capacity (Qº) is 122 mg/g and 122 mg/g with Freundlich model for an initial iron concentration of 2.37% contained in crude phosphoric acid. Characterization studies such as x-ray diffraction, infrared spectroscopy and electron scanning microscope were investigated to substantiate the nature of iron-OSC complexes

EFFECT OF ANAEROBIC PROBIOTIC AND/OR BIOLOGICAL ANTITOXIN SUPPLEMENTATIONS ON PRODUCTIVE AND REPRODUCTIVE PERFORMANCE OF LACTATING COWS

Forty-eight lactating Holstein Friesian cows were utilized to assess impact of supplementing probiotic ZAD (mixture of live bacterial cells and enzymes) compared with T5X (antitoxins product) on some productive, reproductive and antitoxins activity parameters. we have divided the animals to three experimental categories (16 each). The first category, control treatment, was fed basal diet without any supplements. The second category, ZAD treatment, was fed basal diet supplemented with ZAD probiotic (1.1 L/ton). The third category, T5X treatment, was fed basal diet supplemented with T5X antitoxins product (1.1 Kg/ton). Milk yield was recorded. we have collected and analyzed milk samples, blood samples and feed samples in order to constitutes. Time-interval between calving and fertilizing artificial insemination and pregnancy rate were recorded. The gained outcomes demonstrated that milk yield was significantly raised by ZAD treatment than other treatment. Milk components yield were significantly raised by ZAD probiotic and T5X treatments than control. Blood serum total protein, albumin, globulin, glucose, urea and total lipids were not significantly influenced by treatments. Total aflatoxins in concentrate mixture and aflatoxin M1 in milk were significantly diminished by ZAD and T5X than control. Number of days between calving and fertilized artificial insemination were diminished by treatments than control. Pregnancy rate was significantly raised by ZAD  probiotic than T5X and control treatments, respectively. The overall conclusion of this study illustrated that Probiotic ZAD, potentially, has antitoxins activity leading to reinforcing the productive and reproductive performance of lactating cows

Nutrient Digestibility, Ruminal Fermentation Activities, Serum Parameters and Milk Production and Composition of Lactating Goats Fed Diets Containing Rice Straw Treated with Pleurotus ostreatus

The study evaluated replacement of Egyptian berseem clover (BC, Trifolium alexandrinum) with spent rice straw (SRS) of Pleurotus ostreatus basidiomycete in diets of lactating Baladi goats. Nine lactating homo-parity Baladi goats (average BW 23.80.4 kg) at 7 d postpartum were used in a triplicate 33 Latin square design with 30 d experimental periods. Goats were fed a basal diet containing 0 (Control), 0.25 (SRS25) and 0.45 (SRS45) (w/w, DM basis) of SRS. The Control diet was berseem clover and concentrate mixture (1:1 DM basis). The SRS45 had lowered total feed intake and forages intake compared to Control. The SRS25 and SRS45 rations had the highest digestibilities of DM (p = 0.0241) and hemicellulose (p = 0.0021) compared to Control which had higher (p<0.01) digestibilities of OM (p = 0.0002) and CP (p = 0.0005) than SRS25 and SRS45. Ruminal pH and microbial protein synthesis were higher (p<0.0001) for SRS25 and SRS45 than Control, which also had the highest (p<0.0001) concentration of TVFA, total proteins, non-protein N, and ammonia-N. All values of serum constituents were within normal ranges. The Control ration had higher serum globulin (p = 0.0148), creatinine (p = 0.0150), glucose (p = 0.0002) and cholesterol (p = 0.0016). Both Control and SRS25 groups had the highest (p<0.05) milk (p = 0.0330) and energy corrected milk (p = 0.0290) yields. Fat content was higher (p = 0.0373) with SRS45 and SRS25 groups compared with Control. Replacement of BC with SRS in goat rations increased milk levels of conjugated linoleic acid and unsaturated fatty acids compared with Control. It was concluded that replacing 50% of Egyptian berseem clover with SRS in goat rations improved their productive performance without marked effects on metabolic indicators health. (Key Words: Fungus, Goats, Milk, Spent Rice Straw

Effects of sun-drying and exogenous enzymes on nutrients intake, digestibility and nitrogen utilization in sheep fed Atriplex halimus foliages

This study was conducted to assess effects of sun-drying and/or addition of an exogenous enzyme (ENZ) preparation on intake, digestibility of nutrients and recovery values of secondary metabolites (SM) in the gastrointestinal tract of sheep fed Atriplex halimus (AH) foliages. A randomized block design for 28 d was used for four experimental treatments based on either fresh (AH-F) or sun-dried (AH-S) A. halimus foliages in the absence (−ENZ) or presence (+ENZ) of 10 g/sheep/d of the exogenous of ZADO® enzyme preparation. Three adult sheep weighing 51 ± 2.7 kg were fed for each experimental treatment. The ENZ was added daily with a small amount of concentrate to help balance the dietary metabolizable energy concentration. Nutrient intake and digestibility, N balance and recovery of SM (i.e., total phenolics (TP), saponins (SP), alkaloids (AK), aqueous fraction (AF)) in the gastrointestinal tract were determined. Levels of most nutrients did not differ between AH-F and AH-S foliages, but the AH-S contained less than half of the SM in AH-F. Drying of A. halimus and ENZ addition increased (P=0.001) intake as well as OM and NDFom digestibility (P=0.02). Feed intake and digestibility were higher (P=0.01) in AH-S with ENZ addition. Intake of N by sheep fed the treatment diets depended on DM intake as the dietary concentration of N in the diets was similar. Thus AH-S sheep supplemented with ENZ had higher (P=0.001) N intake. Digestibility of N was similar to DM and OM digestibility, and was higher (P=0.03) in AH-S sheep supplemented with ENZ. Drying and ENZ addition to the diet increased (P=0.004) recovery of all SM. The fate of these compounds in the rumen needs to be evaluated considering that SM have been implicated in fiber and protein degradation in the rumen. The study showed that there are beneficial impacts of sun-drying and/or dietary exogenous enzyme addition for sheep fed A. halimus

Columnar and lamellar phases in attractive colloidal systems

In colloidal suspensions, the competition between attractive and repulsive interactions gives rise to a rich and complex phenomenology. Here, we study the equilibrium phase diagram of a model system using a DLVO interaction potential by means of molecular dynamics simulations and a thermodynamical approach. As a result, we find tubular and lamellar phases at low volume fraction. Such phases, extremely relevant for designing new materials, may be not easily observed in the experiments because of the long relaxation times and the presence of defects.Comment: 5 pages, 5 figure

IN VITRO EVALUATION OF ENSILING AND /OR EXOGENOUS FIBROLYTIC ENZYME SUPPLEMENTATION OF DATE PRESS CAKE

This study was conducted to evaluate the effect of ensiling and /or exogenous fibrolytic enzyme supplementation date press cake using in vitro batch culture technique . Untreated date press cake (DPC) and ensiled DPC with exogenous fibrolytic enzymes (ZAD1 and ZAD2) and with or without adding urea compared to corn grains were in vitro evaluated using batch culture technique. DM, NDF and ADF degradation and total gas production as well as fermentation parameters of the incubated samples were determined after 24 h of fermentation. Total VFAs, proportions are not affected (P > 0.05) by any of the treatments. However, value of ammonia concentration was higher (P 0.05) with the ensiling treatments. There were no significant differences in the values of DMD and OMD between the different treatments. But, the values of NDFD and ADFD were increased (P0.05) between the corn grain and the DPC without any treatments. While, values of metabolizable protein (MP) and efficiency of microbial biomass production (EMP) were increased (p<0.05) with DPC compared to corn grains . There was no significant difference in the rumen activity when using date press cake (DPC) or corn grains. Moreover, the ensiling process did not cause a clear improvement in rumen fermentation

The shear modulus of metastable amorphous solids with strong central and bond-bending interactions

We derive expressions for the shear modulus of deeply-quenched, glassy solids, in terms of a Cauchy-Born free energy expansion around a rigid (quenched) reference state, following the approach due to Alexander [Alexander, Phys. Rep. 296, 1998]. Continuum-limit explicit expressions of the shear modulus are derived starting from the microscopic Hamiltonians of central and bond-bending interactions. The applicability of the expressions to dense covalent glasses as well as colloidal glasses with strongly attractive and adhesive bonds is discussed

Dynamics of gelling liquids: a short survey

The dynamics of randomly crosslinked liquids is addressed via a Rouse- and a Zimm-type model with crosslink statistics taken either from bond percolation or Erdoes-Renyi random graphs. While the Rouse-type model isolates the effects of the random connectivity on the dynamics of molecular clusters, the Zimm-type model also accounts for hydrodynamic interactions on a preaveraged level. The incoherent intermediate scattering function is computed in thermal equilibrium, its critical behaviour near the sol-gel transition is analysed and related to the scaling of cluster diffusion constants at the critical point. Second, non-equilibrium dynamics is studied by looking at stress relaxation in a simple shear flow. Anomalous stress relaxation and critical rheological properties are derived. Some of the results contradict long-standing scaling arguments, which are shown to be flawed by inconsistencies.Comment: 21 pages, 3 figures; Dedicated to Lothar Schaefer on the occasion of his 60th birthday; Changes: added comments on the gel phase and some reference

Acacia senegal gum exudate offers protection against cyclophosphamide-induced urinary bladder cytotoxicity

Cylophosphamide (CYCL) is a strong anticancer and immunosuppressive agent but its urotoxicity presents one of the major toxic effects that limit its wide usage particularly in high dose regimens. Therefore, this study aimed to investigate Acacia Senegal gum exudate, Gum Arabic (GA), for its possible role as a natural, nontoxic agent against CYCL-induced urotoxicity. Male Swiss albino rats were exposed to CYCL (150 mg/kg BW, once i.p) with or without GA oral supplementation (7.5 g/kg/day for 6 days) through drinking water. Glutathione (GSH), Malondialdehyde (MDA) and Nitric oxide (NO) bladder contents were assessed. Responsiveness of the bladder rings to acetylcholine (ACh) in vitro, microscopic and macroscopic features are also investigated. CYCL produced pronounced harmful effects on bladder urothelial lining with significant increases in (MDA) and NO levels in the tissue homogenates. Bladder-GSH content is dropped by over 60% following CYCL injection. Bladder contractility, as measured by its responsiveness to ACh, recorded a marked reduction. The isolated bladders exhibited such macroscopic changes as severe edema, inflammation and extravasation. The bladder weight increased as well. Histological changes were evident in the form of severe congestion, petechial hemorrhage and chronic inflammatory reaction in the lamina propria accompanied with desquamated epithelia. GA, a potential protective agent, produced an almost complete reversal of NO induction, lipid peroxidation or cellular GSH bladder contents in the GA + CYCL-treated group. Likewise, bladder inflammation and edema were reduced. Bladder rings showed a remarkable recovery in their responsiveness to ACh. Bladder histological examination showed a near normal configuration and structural integrity, with a significant reduction in inflammation and disappearance of focal erosions. These remarkable effects of GA may be attributed to its ability to neutralize acrolein, the reactive metabolite of CYCL and/or the resultant reactive oxygen metabolites, through a scavenging action. GA may limit the cascading events of CYCL-induced damage, initiating a cytoprotective effect leading to structural and functional recovery of the bladder tissues