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A total of 1,360 pigs were used in a 125-d study to determine the effects of corn dried distillers grains with solubles (DDGS) withdrawal after immunological castration (Improvest, Zoetis, Kalamazoo, MI) on growth performance and carcass fat quality of pigs. Pens of male pigs (initially 24 kg) were randomly allotted by BW and castration method (physically castrated [PC] or immunologically castrated [IC] barrows) to 1 of 3 diets with 8 replications per treatment and 27 to 29 pigs per pen. Treatments were arranged in a 2 × 3 factorial with main effects of castration method and diet (0% DDGS throughout, 30% DDGS throughout, or 30% DDGS through d 75 then no DDGS to d 125). Intact males were injected with Improvest on d 39 and 74 (IC). No castration method × diet interactions (P > 0.12) were observed for growth performance. Before the second Improvest injection (d 0 to 74), PC barrows had increased (P < 0.05) ADFI but were less efficient (P < 0.05) than intact males. After the second Improvest injection until the first marketing event (d 74 to 107), IC barrows had improved (P < 0.05) ADG and G:F compared with PC barrows. From d 0 to 107, IC barrows had improved (P < 0.05) ADG, G:F, and lower ADFI than PC barrows. The inclusion of 30% DDGS decreased (P < 0.05) G:F compared with pigs fed the control diet. For the period after the second Improvest injection (d 74 to 125), IC barrows had increased (P < 0.05) ADG, ADFI, and G:F compared with PC barrows. Overall (d 0 to 125), IC barrows had improved (P < 0.05) ADG and G:F and lower ADFI than PC barrows. The inclusion of 30% DDGS decreased (P < 0.05) G:F. Carcass yield was lower (P < 0.05) for IC than PC barrows. Pigs fed 30% DDGS throughout had decreased (P < 0.05) carcass yield; however, withdrawing DDGS from the diet on d 74 was effective at fully recovering the yield loss. Carcass fat iodine values (IV) were consistently higher (P < 0.05), regardless of fat depot or harvest time when 30% DDGS were included in the diet. Multiple 2-way interactions (P < 0.05) were detected between castration method, DDGS, depot, and time. Interactions were a result of fatty acid profiles changing more rapidly in backfat and belly fat than in jowl fat from d 107 to 125 and more dramatically in IC than PC barrows in the same period. This improvement from d 107 to 125 could be caused by the dilution of unsaturated fatty acids, specifically C18:2 and C18:3, due to rapid deposition of fat from de novo synthesis in IC barrows.

In the OH radical-induced oxidation of cyclo-Met-Met an OH adduct,cyclo-Met-Met(S∴OH), absorbing at γmax = 390 nm with e390cyclo-Met-Met(S∴OH) = 4500 dm3 mol−1 cm−1 is formed. This adduct reversibly eliminates hydroxide ion, pKb = 5.4 ± 0.1, forming corresponding (S ∴ S)-bonded radical cation, cyclo-Met-Met(S ∴ S)+, which absorbs at γmax = 510 nm with e510cyclo-Met-Met(S ∴ S)+ = 6200 ± 400 dm3 mol-1 cm-1. The OH- elimination is catalysed by H+ and buffers. The rate constants are k=(1.4 ± 0.1)×109dm3mol−1s−1 and k=(1.0±0.1)×104s−1 for the H+ catalysed and uncatalysed reactions, respectively. The rate constant for the reverse reaction is k[cyclo-Met-Met(S ∴ S)+ + OH-] = (2.6 ± 0.3) × 109 dm3 mol-1 s-1. A certain amount of cyclo-Met-Met(S |.: S)+, G ≈ 1, is formed immediately after the pulse, independently of the actual equilibrium position. Therefore, the existence of at least two different precursors of the cyclo-Met-Met(S ∴ S)+ is inferred.

Vitamin E is involved in the protection of cellular membranes against lipid peroxidation by scavenging free oxygen centered radicals (1,2), e.g. in the general reaction.

The radiation chemical method of pulse radiolysis is introduced as a suitable tool for the analysis of time-resolved optical changes in radiolytically induced redox and alkylation reactions. A pseudo-first order reaction observable in the radiolysis of C60 in 2-propanol leads to the formation of the radical anion in the reaction of C60 with solvated electrons and dimethylhydroxymethyl radicals. One-electron oxidation in 1, 2-dichloroethane (1, 2-DCE) yielded C60 •+, achieved via interaction of C60 with the radiolytically generated oxidizing (l, 2-DCE)•+ radical cations. The reaction of methyl radicals with C60 resulted in absorption changes which are very different from redox reactions and are ascribed to the methylation of the fullerene. Corresponding experiments in aqueous solutions have been carried out by incorporating C60 into artificial bilayer membranes and larger organic molecules. Several absolute rate constants for the radical induced reactions have been determined.

SummaryThe primary steps of the oxidation of methionine, Met, by X (X = Cl· Br I SCN) have been investigated using pulse radiolysis techniques. In principle, the mechanism follows the same pattern which has been established for the OH· radical induced oxidation. It is characterized by a primary attack at the sulphur atom and the formation of sulphur-centred radical cations and as key intermediates. At pH > pKa of the carboxyl group these can then oxidize the amino function intramolecularly, which subsequently leads to irreversible decarboxylation. An additional important intermediate is a radical with a three-electron bond between sulphur and halide. This radical is linked to the OH· radical induced mechanism through the equilibrium + Met⇌ + X−, and in addition exists in the equilibria X + Met⇌ + X−, ⇌ + X− and ⇌Met + X·. The species absorb at 410, 400, and 390 nm for X = I, Br, and Cl, respectively. Absolute rate constants have been measured for the reactions + I− (k = 1·0 × 1010 mol−1 ls−1, pH 1·4), Br ...

Oxidation of methionine by Tl2+ and Ag2+ occurs with bimolecular rate constants of 2.5 x 10(9) and 3.3 x 10(8) mol-1 ls-1, respectively, and lead to sulphur-centred radical cations as primary intermediates. The overall mechanism is in principle the same as for OH. and X2.- (X = halide) induced oxidations with however one significant difference. Thus no oxidation of the amino group by S+. including subsequent decarboxylation is observed for methionine in its zwitterionic form while this readily occurs in the OH. and X2.- initiated mechanism. The reason is suggested to be complexing of the amino function by the metal ions which effectively lowers the reduction potential of the amino group. The sulphur-centred radical cation rather decays by a mostly first-order deprotonation process to yield CH2-S-CH2 approximately and CH3-S-CH approximately radicals of methionine. They absorb with lambda max = 290 mm and epsilon = 3000 +/- 600 mol-1 l cm-1, and exhibit reducing properties.

Absolute rate-constants for the reaction of the nitroxyl free radicals TAN and TMPN with radiation-chemically-formed radicals and ions have been determined. k(TAN + X) (in M(-1) sec(-1)=4-0 X 10(9) (for X = OH-), 2-9 X 10(10) (eaq-), 8-0 X 10(9) (H-), 7-2 X 10(8) (-CH2OH), 4-0 X 10(8) (CH3CHOH), 4-3 X 10(8) ((CH3)2COH) 2-8 X 10(8) (-CH2(CH3)2COH), 5-9 X 10(7) (glucose radical), 4-0 X 10(8) (c-C5H9-), and k(TMPN + X)=3-4 X 10(9) (OH-), 7-8 X 10(9) (eq-), 4-9 X 10(9) (H-), 4-4 X 10(8) (-CH2OH), 4-9 X 10(8) (CH3CHOH), 3-6 X 10(8) ((CH3)2COH), 1-5 X 10(8) (-CH2(CH3)2COH), 4-9 X 10(7) (glucose radical), 4-3 X 10(8) (c-C5H9-). Direct measurements by means of a pulse-radiolysis conductivity technique were based on the formation and destruction of charged species in these reactions within certain pH ranges. It is indicated that the radiosensitizing nitroxyls undergo both redox and addition reactions.

Phosphite radicals HPO/sub 3/- and PO/sub 3//sup 2/-, which exist in an acid-base equilibrium with pK = 5.75, are shown to take part in various types of reactions. In the absence of scavengers, they disappear mainly by second-order disproportionation and combination; a first-order contribution to the decay is also indicated. HPO/sub 3/- and PO/sub 3//sup 2/- are good reductants toward electron acceptors such as tetranitromethane. In this reaction phosphate and C(NO/sub 2/)/sub 3/- are formed. Phosphite radicals can, however, also act as good oxidants, e.g., toward thiols and thiolate ions. These reactions lead to the formation of RS. radicals which were identified either directly, as in the case of penicillamine, through the optical absorption of PenS. or more indirectly through equilibration of RS. with RS- to the optically absorbing RSSR-. disulfide radical anion. A homolytic substitution reaction (S/sub H/2) occurs in the reaction of the phosphite radicals with aliphatic disulfides, yielding RS. radicals and phosphate thioester RSPO/sub 3//sup 2/-. Lipoic acid, as an example of a cyclic disulfide, is reduced to the corresponding RSSR-. radical anion and also undergoes the S/sub H/2 reaction with about equal probability. An addition reaction is observed between phosphite radicals and molecular oxygen. The resultingmore » peroxo phosphate radicals establish an acid-base equilibrium HPO/sub 5//sup -/. reversible PO/sub 5//sup 2 -/. + H+ with a pK = 3.4. Absolute rate constants were determined for all reactions discussed.« less

Red phosphorus, soluble phosphorus organic compounds and small amounts of phosphine are formed when white phosphorus in cyclohexane solution is exposed to γ-rays. The red phosphorus contains one C6H11-group per 4 — 5 P-atoms. It reacts with chlorine to give cyclohexylphosphorusdichloride. Its reactivity towards oxygen can be decreased by high temperatures during irradiation or by high γ-doses. It is concluded from quantitative studies of this “annealing” process that phosphorus atoms carrying C6H11-endgroups are especially reactive in the polymeric form of phosphorus. The low molecular weight products of the reaction between white phosphorus and cyclohexane undergo typical reactions of tertiary phosphines. They can readily be oxidized and chlorinated to yield cyclohexyl-phosphinic-acid or cyclohexyl-phosphorus-dichloride, respectively. White phosphorus acts as a scavenger for free H-atoms and C6H11-radicals from the radiolysis of cyclohexane. This reaction, however, does generally not lead to the complete cracking of all PP-bonds of the P4-molecule. The following products are formed in the γ-irradiation of white phosphorus in cyclohexane in the presence of carbon tetrachloride: Red phosphorus containing C6H11- and CCl3-endgroups, cyclohexylphosphorus-dichloride, trichloromethyl-phosphorus-dichloride, chloroform, cyclohexyl-chloride, hexachloroethane and trichloromethyl-cyclohexane. The yields of these products at various doses, dose rates, temperatures and compositions of the solutions are described. Several products such as C6H11PCl2 are produced with high G-values at temperatures above 100°C. The results are explained by a reaction scheme in which three chain reactions simultaneously occur. They are linked together since they have a common intermediate in the form of the CCl3-radical. At high doses, the reaction products of phosphorus mentioned above (including the red phosphorus) are transformed into soluble organic phosphorus compounds of high boiling points the structure of which has not yet been recognized.

Polyethylene terephthalate (PETP) forms the basis of a new plastics material, Hostadur®, which is suitable for mouldings in engineering applications which are subject to mechanical stress. The crystallisation behaviour of PETP is discussed as this is an important factor if economic processing by injection moulding is to be obtained. Short-term properties of the material such as stiffness, strength and toughness were found to be good. Creep rupture strength, and fatigue strength under alternating stress, as well as other long-term properties, were found to be better than with other thermoplastics such as polyamides and polyacetals.

The formation of HD in the reaction of ND 3 with positive solvent ions in γ-irradiated cyclohexane solutions has been investigated as a function of solute concentration. From the observed concentration dependence the competition between geminate recombination and the scavenging reaction for the positive ions of cyclohexane is described by the reactivity parameter α ND 3 = 0·85 mol −1 . The yield of HD is decreased upon addition of C 2 H 4 to the ND 3 -cyclohexane solution. This has been found to be due to the fact that ethylene competes with ammonia for the positive ions and also scavenges hydrogen atoms. A quantitative treatment of these data shows that most of the HD ( ca. 75 per cent) is formed via thermal hydrogen atoms produced upon neutralization of ammonium ions with electrons. G (HD) also is decreased in solutions containing electron scavengers in addition to the ND 3 . It is concluded that the reaction of ammonium ions with secondary negative ions does not yield free hydrogen atoms. Quantitative aspects on the basis of ion pair lifetimes are discussed.

The reduction of carbon tetrachloride by hydrated electrons, H atoms and reducing radicals has been investigated by pulse radiolysis conductivity methods. It has been found that one Cl® ion is formed per reducing species. A chain reaction is observed in the γ-radiolysis of solutions of CCl4 and iso-propanol, diethylether, and tetrahydrofurane. Mechanisms and kinetic data are discussed.

Tetranitromethan (TNM) reagiert mit freien H-Atomen und hydratisierten Elektronen aus der γ-Radiolyse des Wassers, wobei je Atom bzw. Elektron eine Molekel Nitroform entsteht. Die Nitroformausbeute, die gleich ist der Summe G (H) + G (e), nimmt mit steigender Konzentration des TNM langsam zu, was auf das Eingreifen des TNM in nmolekulare“ Prozesse innerhalb der Ionisations- und Anregungsgruppen zuruck-gefuhrt wird. In Gegenwart von N2O wird eine geringere Nitroformausbeute beobachtet. Die quantitative Untersuchung dieser Abnahme fuhrte zu folgenden Ausbeuten und Geschwindigkeitskonstanten: G(Hα) = 0,6, G (e) = 2,7,k = 6,2 · 1010 Mol−1 liter sec−1. In Gegenwart von 0,2 Mol/l Isopropanol betragt die Nitroformausbeute 6,3. Daraus wird abgeleitet, das in der γ-Radiolyse des Wassers OH-Radikale mit einer Ausbeute von 3,0/100 eV erzeugt werden. (Alle Ausbeuten gelten fur eine 6,4 · 10−4 molare TNM Losung.) Tetranitromethane (TNM) was found to react with free H-atoms and hydrated electrons produced in the γ-radiolysis of water. One molecule of trinitromethane is formed per atom or electron, respectively. The yield of trinitromethane, which is equal to the sum of G (H) and G (e), slowly increases with TNM-concentration. This is explained by the influence of TNM on “molecular” processes in the spurs. In the precence of N2O, lower yields of trinitromethane were observed. The quantitative investigation of this decrease led to the following yields and rate constant: G (Hα) = 0,6 G (e) = 2,7,k = 6,2 · 1010 mole−1 liter sec−1. The yield of trinitromethane amounts to 6.3 when isopropanol is present at 0.2 moles/liter. It follows from this observation that OH-radicals are formed with a yield of 3.0/100 eV in the γ-radiolysis of water. (All yields refer to a 6.4 · 10−4 molar TNM-solution.)

Die absoluten bimolekularen Geschwindigkeitskonstanten der Reaktionen des Tetranitromethans mit hydratisierten Elektronen, Wasserstoffatomen, verschiedenen Alkoholradikalen und mit den Ionen O2−, CH3COCH3− und Cu+ wurden bestimmt. Ferner wird ein Verfahren beschrieben, um Tetranitromethan als „Indikator” fur freie Radikale, die keine starke Lichtabsorption besitzen, zu verwenden. Auf diese Weise wurde die Reaktion OH + CH3OH H2O + CH2OH untersucht. Alle Reaktionen des Tetranitromethans sind sehr schnell und werden im wesentlichen durch die Diffusion der Reaktanden kontrolliert. Die Bildung des aci-Nitroforms bei diesen Reaktionen wird auf die Ubertragung eines Elektrons von dem Reaktionspartner auf das Tetranitromethan mit sofortiger Dissoziation des negativen Molekelions zuruckgefuhrt. Freie neutrale Radikale ubertragen etwa gleich schnell wie negative Radikalionen, wahrend die Ubertragung vom Cu+-Ion langsamer geschieht. Fur die Reaktion des OH-Radikals mit Methanol wurde eine uberraschend hohe Geschwindigkeitskonstante von mehr als 3 · 109 Mol−1 1 sec−1 gefunden; auch dieser Prozes scheint demnach weitgehend durch die Diffusion der Reaktionspartner bestimmt zu sein. The absolute rate constants of the reactions between tetranitromethane and hydrated electrons, hydrogen atoms, various alcohol radicals and the ions O2−, CH3COCH3− and Cu+ have been determined. A procedure is also described to use tetranitromethane as „indicator” for free radicals which have no strong light absorption. The reaction OH + CH3OH H2O + CH2OH has been investigated this way. All reactions of tetranitremethane are very fast and essentially are controlled by the diffusion of the reactands. The formation of aci-nitroform in these reactions is explained by electron transfer from the reaction partner to tetranitromethane and immediate dissociation of the negative molecule ion. Neutral free radicals transfer the electron about as fast as negative radical ions while a slower transfer occurs from the Cu+-ion. A surprisingly high rate constant of more than 3 · 109 mole−1. 1 sec−1 has been found for the reaction of the OH radical with methanol. It therefore seems that this process is also determined by the diffusion of the reactands.

The reactions of chlorinated ethylenes with hydrated electrons and OH radicals have been investigated by using the method of pulse radiolysis. In addition γ-ray experiments were carried out. The reduction of the solutes occurs via a dissoziation electron capture process. The rate constant for the reaction of eaq ⊖ with the more chlorinated compounds is essentially diffusion controlled (k= (1 - 2×1010 l-mole-1 sec-1). Vinylchloride and 1,2-trans-dichloroethylene react more slowly. This can be related to the higher stability of the C-Cl bond in these compounds. Hydroxyl radicals add to the C=C double bond of the chlorinated ethylenes. The rate constant for the reaction with vinylchloride was determined to 7.1 × 109 1 · mole-1 sec-1, and decreases with increasing degree of chlorination of the ethylenes. This effect is explained by the decreasing electron density on the C-atoms and steric hinderance. The hydroxyl radical always adds to the C-atom carrying the smallest number of Cl-atoms. In its reaction with 1,2-dichloro-, trichloro- and tetrachloroethylene a radical is produced with an OH group and a Cl-atom on the same C-atom. It eliminates HCl to form a C=O bond with k>7 × 105 sec-1. The type radical produced in this reaction has an optical absorption in the near UV (ε265 nm = (1-3)×103 1 · mole-1 cm-1). The OH radical addition products of vinylchloride and 1,1-dichloroethylene do not eliminate HCl and have no absorption in the visible and near UV.

Es wurden pulsradiolytische und γ-strahlenchemische Versuche zur Reduktion von halogenierten organischen Verbindungen durch hydratisierte Elektronen durchgefuhrt. Dissoziativer Elektroneneinfang setzt aus verschieden chlorierten Methanen, athylenen sowie fluorierten Benzolen Halogenionen frei. Diese wurden mit Hilfe von Leitfahigkeitsmessungen bei der Pulsradiolyse und mit Ionen-sensitiven Elektroden bei den γ-Versuchen quantitativ nachgewiesen. Die Geschwindigkeitskonstanten der Reaktion des eaq− mit den mehrfach halogenierten Verbindungen sind praktisch ausschlieslich durch die Diffusion der Reaktionspartner zueinander bestimmt. Bei den wenig halogenierten Substanzen verlauft die Reaktion langsamer, was mit der groseren Stabilitat der Halogen-Kohlenstoffbindung in Einklang steht. Die primaren Reaktionsprodukte sind Halogenionen und neutrale, kurzlebige Radikale, die keinerlei optische Absorption im Wellenlangenbereich von 250–800 nm aufweisen. Alkohol- und Atherradikale ubertragen ein Elektron auf CCl4. Dies stimmt mit der Tatsache uberein, das die Halbstufenpotentiale fur die Oxidation dieser Radikale negativer sind als dasjenige fur die Reduktion des CCl4. Die theoretisch ebenfalls mogliche Elektronenubertragung vom CO2−-Radikalion auf Tetrachlorkohlenstoff findet nicht statt, da offensichtlich eine zu hohe Aktivierungsenergie fur diese Reaktion vorliegt. The reduction of halogenated organic compounds by hydrated electrons has been investigated by means of pulse radiolysis and γ-irradiation. Halide ions are produced in a dissociative electron capture process by chlorinated methanes and ethylenes, and fluorinated benzenes. A quantitative analysis of the halide ion yield has been carried out by conductivity pulse radiolysis methods, and with ion specific electrodes. The rate constants of the reaction of hydrated electrons with the highly halogenated compounds were found to be essentially diffusion controlled. The slower reaction of eaq− with the less halogenated compounds is explained by the higher stability of the carbon-halogen bond in these molecules. The primary products of the dissociative electron capture process are halide ions and neutral radicals which have no optical absorption in the 250–800 nm range. Carbon tetrachloride is also reduced by an electron transfer reaction from alcohol and ether radicals. This agrees with the fact that the halfwave oxidation potential of these radicals is more negative than the halfwave reduction potential of CCl4. A theoretically possible electron transfer process from CO2− ions to CCl4 has not been observed, presumably due to a high activation energy of this reaction.

Tetranitromethane (TNM) reacts by a dissociative electron capture process with solvated electrons in isopropanol (kTNM + e–s= 2.45 × 1010 M–1 s–1) to produce nitroform anions, C(NO2)–3, and NO2. Iso-propanol radicals and iso-propanolperoxy radicals also reduce TNM via an electron transfer reaction with bimolecular rate constants of 7 × 109 M–1 s–1 and 9 × 108 M–1 s–1, respectively. In neutral and acid (HClO4) solutions C(NO2)–3 ions are neutralized to C(NO2)3H by reaction with solvated protons (k= 3.2 × 108 M–1 s–1) and by a proton transfer reaction from isopropanol molecules (k= 4.5 × 102 M–1 s–1). C(NO2)3H dissociates with k= 3.2 × 103 s–1. The equilibrium constant of C(NO2)3H ⇌ C(NO2)–3+ H+sol in isopropanol was determined to be K= 1.0 × 10–5 M. The yield of scavengable reducing species in irradiated isopropanol increases from G= 3.5 at 6.3 × 10–6 M TNM to G= 6.4 at 3.2 × 10–2 M TNM in argon saturated solutions, and from G= 0.75 to G= 4.2 for the same concentrations of TNM in O2 saturated solutions. G(free solvated electrons) was measured to be 1.2. The formation and disappearance of ions have been observed directly by means of pulse radiolysis conductivity measurements. The specific equivalent conductance of C(NO2)–3 ions and solvated protons was determined to be ΛC(NO2)3–+ Hsol+= 51 Ω–1 cm2 equiv.–1.

The absorption spectra of the radicals HC6H5NO2 and OHC6H5NO2 in aqueous solutions have been obtained. These transients have a strong absorption at 4100 A and their molar extinction coefficients are both 3700 M–1 cm–1. The following rate constants have been measured : k(H+C6H5NO2)=(5.6±0.6)× 109 M–1 sec–1; k(OH+C6H5NO2)=(4.7±0.5)× 109 M–1 sec–1; k(O2+OHC6H5NO2)=(2.3±0.3)× 106 M–1 sec–1; k(OHC6H5NO2+OHC6H5NO2)=(6.0±0.4)× 108 M–1 sec–1. About 25% of the reactions between two nitro-hydroxycyclohexadienyl-radicals lead to nitrophenol-isomers by disproportionation. The majority of these reactions lead to other products (probably dimers by combination) which exist in acid and basic forms, the latter having strong absorptions in the visible range. These products are believed to be derivatives of nitro-cyclohexadiene.

The dissociation equilibrium C(NO2)3H ⇌ C(NO2)–3+ H+sol and the related kinetics have been studied for various solvents (alcohols, acetone, and water) by means of pulse radiolysis. Nitroform anions were produced by radiation-chemical reduction of tetranitromethane which was dissolved in these liquids. The dissociation constant K of nitroform decreases with decreasing dielectric constant; its value ranges from 6.3 × 10–1 M for water to 2.5 × 10–7 M for t-butanol. K is essentially controlled by the rate constant kn for the neutralization of C(NO2)–3 by solvated protons (3.4 × 104 M–1 s–1 in water and 5.0 × 109 M–1 s–1 in t-butanol), while the rate of dissociation of C(NO2)3H depends relatively little on the nature of the solvent. A linear relationship has been found between log kn and log K. Nitroform anions are also neutralized by proton transfer from solvent molecules. The rate constant for this process does not vary much with the properties of the solvent. Equivalent conductivities for C(NO2)–3+ H+sol ion pairs have also been determined.