Complex viscosity behavior and cluster formation in attractive colloidal systems

The increase of the viscosity, which is observed in attractive colloidal systems by varying the temperature or the volume fraction, can be related to the formation of structures due to particle aggregation. In particular we have studied the non trivial dependence of the viscosity from the temperature and the volume fraction in the copolymer-micellar system L64. The comparison of the experimental data with the results of numerical simulations in a simple model for gelation phenomena suggests that this intriguing behavior can be explained in terms of cluster formation and that this picture can be quite generally extended to other attractive colloidal systems.Comment: 5 pages, 4 figure

Hydraulic Jump in Circular Open Channels with Mild Slope

A hydraulic jump is a well-known transitionalphenomenon from supercritical to subcritical flows withundulations of water-surface. In this transition, the water flowhas a high-velocity, water surface rises abruptly, surface rollersare formed, intense mixing occurs, the air is entrained, and alarge amount of energy is dissipated. In the present studycharacteristics of the hydraulic jumps in circular open channelswith a mild sloped have been discussed under a wide range ofexperimental conditions. The study aims to determine the effectof the channel’s mild slope on the characteristics of thehydraulic jumps with circular channels. A theoretical study hasbeen done and led to obtaining equations that can be used to getspecific force for the hydraulic jump that occurred in circularopen channels. A theoretical study is based on usingmomentum, and Froude’s number equations. An experimentalstudy has been investigated using Laboratory 40 experimentalruns in circular section flume for eight different dischargesranged from 3.92 to 12.07 l/sec were given with mild slopeequals 0.000833. In total, the experiments were conducted overa range of Froude numbers from 1.78 to 8.87. The experimentalworks concluded some dimensionless curves and new usefulformulas to get the length of the jump, energy dissipated andefficiency. The conjugated depth ratio is determined and plottedversus the upstream Froude number, downstream Froudenumber, head loss, and efficiency for different values of criticaldepths. The resulting graphs and equations of the present studyare readily applicable for a design for the hydraulic jumps inthe circular open channels with mild slope

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

EFFECT OF PROPIOTIC ON RUMINANT PERFORMANCE

Two hundred multiparous Holstein dairy cows post-partum were randomly assigned into two groups. The first group (control, n=100) was fed total mixed ration (TMR) without a supplement of liquid probiotic enzymes. The second group (treatment, n=100) was fed TMR supplemented with a commercial probiotic (ZAD) prepared by Bactizad company, Cairo, Egypt. at the rate of 10 ml/head/day.  According to the guide of the manufacture for 12 weeks ZAD was added and mixed to the TMR at the time of feeding once per day. Each group was placed in a shaded pen equipped with free stalls.    Results obtained showed that     Milk yield increased significantly from 39.57 kg/day for control group up to 41.73 kg/day for treated with ZAD group.  Fat and protein milk percentage tended to be improved due to treated with ZAD but the difference was not significant. Lactose percentage was affected positively and significantly by treated of ZAD, lactose percentage was 4.79 for control group and 4.83 for ZAD group.  Serum total protein increased significantly from 11.52 (g/dl) for control group up to 11.85(g/dl) for treated ZAD group. Albumin was significantly higher in control group.   Results indicated that blood urea concentration in treated group being 34.77 (mg/dl) and for the control group 33.91 (mg/dl), was significantly higher.  Alkaline phosphates increased significantly in treated group from 21.105 U/l for control group up to 26.92 U/l for treated group.   Cholesterol concentration was reduced significantly due to treatment from 240.98 mg/dl in control cows to 190.13 mg/dl in treated cows.  Triglycerides concentration declined significantly due to treatment of probiotic ZAD. In control cows triglycerides concentration was 27.871 (mg/dl) and treated cows was 20.9781 (mg/dl).  T3 concentration increased significantly as a response to treatment by probiotic ZAD. T3 concentration was 117.29 ng/dl in treated group and 62.38 mg/dl in control group

Stress-stress Correlations Reveal Force Chains in Gels

We investigate the spatial correlations of microscopic stresses in soft particulate gels, using 2D and 3D numerical simulations. We use a recently developed theoretical framework predicting the analytical form of stress-stress correlations in amorphous assemblies of athermal grains that acquire rigidity under an external load. These correlations exhibit a pinch-point singularity in Fourier space leading to long-range correlations and strong anisotropy in real space, which are at the origin of force-chains in granular solids. Our analysis for the model particulate gels at low particle volume fractions demonstrates that stress-stress correlations in these soft materials have characteristics very similar to those in granular solids and can be used to identify force chains. We show that the stress-stress correlations can distinguish floppy from rigid gel networks and the intensity patterns reflect changes in shear moduli and network topology, due to the emergence of rigid structures during solidification.Comment: 11 pages, 9 figure

EFFECT OF BIOLOGICAL TREATMENTS OF GREEN CORN STOVER AND STALKS ON DIGESTIBILITY COEFFICIENTS, RUMEN FERMENTATION AND SOME BLOOD PARAMETERS IN SHEEP

This study aimed to investigate the effect of a mixture of  (ZAD) and (Lacto bacillus plantarum) on chemical composition of green corn stover and corn stalks and the effect of  these treatments in a metabolism trial on digestibility coefficients , rumen fermentation and some blood parameters. One ton of either green corn stover or corn stalks was chopped into (2-3 cm) and  its mixed with 0. 5 cubic metre of water or one cubic metre of water, respectively. They were then mixed with 3%w/w molasses and 1.5%w/w urea and incubated for six weeks. The experiment included six treatments, three of them were on green corn stover and the rest were on corn stalks. The treatments on green corn stover were as follows: (T1) Untreated green corn stover (control). (T2) corn stover + lactobacillus palantarum + ZAD (2litres of ZAD + 1 liter of lactobacillus palantarum / 1ton). (T3) corn stover + ZAD ( 2 liters of ZAD/ 1 ton). The treatments on corn stalks were as follows: (T4) Untreated corn stalks (control). (T5) corn stalks + lactobacillus palantarum+ ZAD (2litres of ZAD +1 liter of lactobacillus palantarum /1ton) (T6) corn stalks + ZAD (2 liters of ZAD/ 1 ton). Eighteen Ossimi male lambs were divided to six group rations for 15 days in metabolism trials. Results indicated that biological treatment on T2 and T3 treatments  on green  stover and T5 and T6 on  dry corn stalks decreased CF and NDF, ADF, ADL contents and increased CP content compared to the control.   Feeding lambs on treated green corn stover or treated dry corn stalks significantly (P<0.05) improved all of nutrients digestibility compared with those fed on control. The nutritive values as TDN,  DCP and N balance for lambs fed treated green stover or treated dry corn stalks showed significant(P<0.05) higher than those fed untreated and it had the same trend of nutrient digestibility . Adding lactobacillus palantarum + ZAD improved digestion coefficients of nutrients and TDN values compared with control. Results of blood parameter indicated that T2 of green corn stover and T5 of corn stalks had a significant (P<0.05) effect on (Tp, Alb, Glb, A/G) compared to the control and T3 of corn stover and T6 of corn stalks. All values of plasma ALT and AST for all treatments were in normal rang where all treatments had no effect on ALT. However, T2 of green corn stover and T5 of corn stalks had a significant (P<0.05) effect on AST compared to the control and T3 of corn stover and T6 of corn stalks. All values of plasma creatinine and urea for biological treatments appeared to significant(P<0.05) higher values. However, these values were in normal range.   Results of rumen parameters indicated that all treatments had no effect on pH and NH3-N. On the other hand T2 of  green corn stover and T5 of corn stalks significantly (P<0.05) increased TVF'S. Generally, Adding enzyme with or without lactobacillus  to green corn stover or dry corn stalks tended to improved nutrient components , digestibility coefficients, feeding values and nitrogen balance with no adverse effect of animal health

Computing the linear viscoelastic properties of soft gels using an Optimally Windowed Chirp protocol

We use molecular dynamics simulations to investigate the linear viscoelastic response of a model three-dimensional particulate gel. The numerical simulations are combined with a novel test protocol (the optimally windowed chirp or OWCh), in which a continuous exponentially varying frequency sweep windowed by a tapered cosine function is applied. The mechanical response of the gel is then analyzed in the Fourier domain. We show that (i) OWCh leads to an accurate computation of the full frequency spectrum at a rate significantly faster than with the traditional discrete frequency sweeps, and with a reasonably high signal-to-noise ratio, and (ii) the bulk viscoelastic response of the microscopic model can be described in terms of a simple mesoscopic constitutive model. The simulated gel response is in fact well described by a mechanical model corresponding to a fractional Kelvin-Voigt model with a single Scott-Blair (or springpot) element and a spring in parallel. By varying the viscous damping and the particle mass used in the microscopic simulations over a wide range of values, we demonstrate the existence of a single master curve for the frequency dependence of the viscoelastic response of the gel that is fully predicted by the constitutive model. By developing a fast and robust protocol for evaluating the linear viscoelastic spectrum of these soft solids, we open the path toward novel multiscale insight into the rheological response for such complex materials

Yrast Band Description of 150Sm, 152Sm, 154Gd and 192Os Nuclei Using VAVMNS Model

In the frame work of the concept of softness parameter ? of nucle

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