Endogenous phosphorus excretion by sheep fed hydrolyzed sugarcane bagasse, lucerne hay and citrus pulp

Summary The objective of this study was to determine endogenous phosphorus excretion in sheep fed with different diets. Sixteen male growing sheep, received a basic diet with: 42% hydrolyzed sugarcane bagasse (HSB), 45% lucerne hay (LH) plus 14% hydrolyzed sugarcane bagasse, and 30% citrus pulp (CTP) plus 40% hydrolyzed sugarcane bagasse. A dose of 7.7 MBq ³²P was injected into the left jugular vein of each animal. The P endogenous fecal losses were: 1.69, 2.50, 2.33 and 1.45 g/animal for treatments HSB, LH, and CTP respectively (P>0.05). The type of diet influenced slight endogenous P excretion but altered excretion of P in urine. Endogenous P excreted in feces (P_F) comes mainly from saliva and represents an important loss of P. The estimation of net requirements of phosphorus (P) for ruminants includes endogenous losses, which is also essential for calculating true absorption of this mineral. Physical structure of the feed may influence endogenous losses, altering the metabolism of P and also the demand of this mineral, therefore being important to know how different feeds affect endogenous P losses.     

Kinetics of Reactions of α,β-Unsaturated Surfactants with Secondary Amines in a Solution

The kinetics of reactions of acrylamide derivatives (acrylamidotrihydroxymethylmethane (TA), sodium 4-acrylamidobutanoate (AA₃), sodium 6-acrylamidohexanoate (AA₅), and sodium 11-acrylamido-undecanoate (AA10)) with piperidine and morpholine in water (for TA, also in DMF, DMSO, and formamide) is studied at 293 K. These compounds are weak surfactant monomers. The critical concentrations of micelle formation (CCM) for them are determined. The self-association of AA₃, AA₅, and AA₁₀ producing micelles results in a decrease in their reactivity compared to the monomeric forms. The rates of the reactions of surfactant monomers (SM) with morpholine and piperidine are described by the second-order rate law w ₀ = k[SM]₀[Amine]₀. An empirical equation is derived that relates the CCM values to the rate constant for the reaction of a surfactant monomer with a secondary amine with charges on the -carbon and oxygen atoms of the amide group of a surfactant monomer. The rates of the reactions of TA with piperidine and morpholine are determined by the electrophilicity (acidity) of the medium, which is favorable for the Michael reaction.     

Effects of Solvents and the Structure of Amines on the Rates of Reactions of α,β-Unsaturated Nitriles and Amides with Secondary Amines

The kinetics of reactions between ,-unsaturated compounds (UCs) (acrylonitrile (AN), acryl-amide (AA), and methacrylamide (MAA)) and secondary amines (As) (piperidine, morpholine, diethanolamine, diethylamine, and dipropylamine) in water, as well as in DMF, DMSO, formamide, and 1,4-dioxane for acrylonitrile, was studied. It was found that w= k[HC]₀[A]₀for all of the test pairs. Viscosity, permittivity, and solvation characteristics, such as solvent polarity, nucleophilicity, and electrophilicity, were taken into account in considering the solvent effect on the overall reaction rate. The electrophilicity (acidity) of a medium was found to exert the greatest effect on the reaction rate. It is believed that an increase in the electrophilicity is favorable for the rapid protonation of the UC–amine intermediate complex. The effects of amine basicity, ionization potential, and dipole moment and the steric parameters of substituents in amine molecules on the rates of reactions between the unsaturated compounds and secondary amines were considered.     

Electroanalytical Study of the Composition of the Raw Pigment Mixtures that Yield the Metallic Lustre on Ceramics. A Link Between Composition and Final Result

Voltammetry of immobilized microparticles was used to study the electrochemistry of the raw pigments that produce the metallic lustre on ceramics after a successful firing. To study this influence of the mixture components on the reduction properties to achieve the metallic lustre, 14 mixtures of illitic clay, Fe₂O₃, HgS, CuO and AgNO₃ were prepared and studied in different media. Iron oxide improves the yield of the reduction of the metals and cinnabar helps a closer reduction of silver to copper reduction and prevents the Ag? Cu alloying because of the formation of silver–mercury adducts. The presence of one of the metals influences the peak position of the other metal. The use of vinegar as diluting agent is not casual, because in this media the reduction of silver takes place at a potential closer to the copper. This electroanalytical technique allowed to distinguish between powders of different composition and offered some information about the role of the components in the reduction of copper and silver and the selection of vinegar to prepare the raw pigment suspensions.     

Synthesis of dihydroxylated prolines and iminocyclitols from five-membered endocyclic enecarbamates. Total synthesis of the potent glycosidase inhibitor (2R,3R,4R,5R)-2,5-dihydroxymethyl-3,4-dihydroxypyrrolidine (DMDP)

cis- and trans-3,4-Dihydroxylated prolines and the iminocyclitol 1,4-dideoxy-1,4-imino ribitol were synthesized employing a strategy involving the Heck arylation of five-membered endocyclic enecarbamates with aryldiazonium salts followed by oxidative cleavage of the electron-rich aromatic ring. The total synthesis of the potent α- and β-glucosidase inhibitor (2R,3R,4R,5R)-2,5-hydroxymethyl-3,4-dihydroxypyrrolidine (DMDP) was also achieved by the same strategy in ten steps from a chiral five-membered enecarbamate in 12% overall yield.     

TRANSIENT ANALYSIS OF COMPOSITE PLATES BY A LOCAL RADIAL BASIS FUNCTIONS-FINITE DIFFERENCE TECHIQUE

The use of local numerical schemes,such as finite differences produces much better conditioned matrices than global collocation radial basis functions methods.However,finite difference schemes are limi...     

Synthesis of pentabromopseudilin and other arylpyrrole derivatives via Heck arylations

Pentrabromopseudilin and other 2 and 3-arylpyrrole derivatives were synthesized through the Heck–Matsuda reaction involving endocyclic enecarbamates and N-protected 3-pyrrolines, respectively. The overall processes permitted an easy and efficient access to these structural motifs present in several bioactive compounds. Attempts to synthesize the compound isopentabromopseudilin led to a tribromo aryl maleimide. We hypothesize that this latter compound is the putative product arising from the unusual thermal instability of isopentabromopseudilin.     

A method for the estimation of the film thickness and plate tilt angle in thin film misaligned plate–plate rheometry

This communication describes a general procedure for the estimation of the true gap and tilt angle in commercially available torsional flow plate–plate rheometers by simply measuring the torque and normal force acting on the plates when shearing a Newtonian fluid.