Time-temperature histories of spherical food products during bulk forced-air precooling

A general mathematical model for forced air precooling of spherical food products in bulk is developed. The food products are arranged inline to form a rectangular parallelepiped. Chilled air is blown along the height of the package. The governing equations for the transient two-dimensional conduction with internal heat generation in the product, simultaneous heat and mass transfer at the product-air interface and one-dimensional transient energy and species conservation equations for the moist air are solved numerically using finite difference methods. Results are presented in the form of time-temperature histories. Experiments are conducted with model foods in a laboratory scale air precooling tunnel. The agreement between the theoretical and experimental results is found to be good. In general, a single product analysis fails to predict the precooling characteristics of bulk loads of food products. In the range of values investigated, the respiration heat is found to have a negligible effect.

Acid-catalysed cyclisations: structures of novel products isolated in the reaction of 2-[3-(2,6-dimethoxyphenyl)but-2-enyl]-2-methylcyclopentane-1,3-dione with MeOH-HCl

Reaction of the title compound (1a) with anhydrous MeOH-HCl gave 2-endo-(2,6-dimethoxyphenyl)-2-exo-methyl-5-methylbicyclo[3.2.1]octane-6,8-dione (3a), 1,5,14-timethoxy-5,8-seco-6,7-dinorestra-1,3,5(10),9(11)-tetraen-17-one (4), 1,5-dimethoxy-5,8-seco-6,7-dinorestra-1,3,5(10),8,14-pentaen-17-one (5), and 3,4,5,6-tetrahydro-2,7-dimethoxy-3,6-dimethyl-3,2,6-(13-oxopropan[1]yI[3]ylidene)-2H-1-benzoxocin (6). Structures assigned to compounds (3a), (4), and (6) are based on spectral data. The exo-tricyclic acetal structure (6) was further confirmed by the analysis of the 1H n.m.r. spectra of the isomeric alcohols (11) and (12), obtained by sodium borohydride reduction of (6).

Mössbauer studies of the corrosion products of iron formed in aqueous ammonium nitrate solution

The products of corrosion reaction of electrolytic iron in 45% ammonium nitrate solution formed under various conditions of time, temperature and pH have been analysed mainly by Mössbauer spectroscopy, in combination with X-ray diffraction, infrared absorption and electron microscopy techniques. γ-Fe00H is found to be the major product of hydrolytic precipitation at pH > 5.6 while only α-FeOOH is formed at pH < 3.0. In the pH range 3.0 < pH < 5.0, α-Fe00H and ferrihydrite are both formed. However, once the nuclei of α-Fe00H are formed under low pH conditions, their growth is favoured even in the otherwise unfavourable slightly acidic medium, resulting in a hydrous α-Fe00H which has two distinct hyperfine fields at the 57Fe nucleus. Magnetite is always formed in the vicinity of the metal and its rate of formation on the surface increases with temperature. α-Fe203 is the major product of hydrolytic precipitation at temperatures >80C. The possible mechanisms for the formation of each of the corrosion products are discussed.

Microbial susceptibility of condensation products of carboxy-terminated polybutadiene and glycerol

Keeping in view the prospects of biodegradable polymers, a polymer was synthesized by the condensation of carboxy-terminated polybutadiene (CTPB) of Mnsim-5000 with glycerol and tested for its microbial susceptibility. The results of end group estimations and viscosity measurements indicated a quantitative reaction between the two reactants under experimental conditions. The clear-zone method was employed in this investigation to test biodegradability. Two strains of Serratia and three strains of Staphylococcus did show a clear zone surrounding the colony. However, the microbial growth was found to diminish after 4 or 5 days.

Novel Oxidation of Pyridoxal in Ternary Metal Complexes. An X-Ray Study of the Products

Attempts to prepare ternary metal complexes of pyridoxylidene-amino acid Schiff bases culminated in the oxidation of pyridoxal to pyridoxic acid or to its lactone and their complex formation, as evidenced from an X-ray study.

Unusual products of oxidation with Cr(VI) of methyl 5-methyl-7-methoxy-8-isopropyl-3,4-2-naphthoate

Abstract is not available.

An extragenic suppressor of prp24-1 defines genetic interaction between PRP24 and PRP21 gene products of Saccharomyces cerevisiae

The temperature-sensitive prp24-1 mutation defines a gene product required for the first step in pre-mRNA splicing. PRP24 is probably a component of the U6 snRNP particle. We have applied genetic reversion analysis to identify proteins that interact with PRP24. Spontaneous revertants of the temperature-sensitive (ts) prp24-1 phenotype were analyzed for those that are due to extragenic suppression. We then extended our analysis to screen for suppressors that confer a distinct conditional phenotype. We have identified a temperature-sensitive extragenic suppressor, which was shown by genetic complementation analysis to be allelic to prp21-1. This suppressor, prp21-2, accumulates pre-mRNA at the non-permissive temperature, a phenotype similar to that of prp21-1. prp21-2 completely suppresses the splicing defect and restores in vivo levels of the U6 snRNA in the prp24-1 strain. Genetic analysis of the suppressor showed that prp21-2 is not a bypass suppressor of prp24-1. The suppression of prp24-1 by prp21-2 is gene specific and also allele specific with respect to both the loci. Genetic interactions with other components of the pre-spliceosome have also been studied. Our results indicate an interaction between PRP21, a component of the U2 snRNP, and PRP24, a component of the U6 snRNP. These results substantiate other data showing U2-U6 snRNA interactions.

Cup products for groups and commutators

We give it description, modulo torsion, of the cup product on the first cohomology group in terms of the descriptions of the second homology group due to Hopf and Miller.

Syntheses of the trans,meso- and racemic C11 acids, degradation products of diterpene acids

Syntheses of the isomers of the C11 acid, 1(a),3(a)- dimethylcyclohexane-1 (e),2(e),3(e)-tricarboxylic acid (A) and 1(a),3(e)-dimethylcyclohexane-1(e),2(e),3(a)-tricarboxylic acid (B), the latter by two different routes, are reported. Two of the four possible isomers of the precursor triester, trimethyl 1-methylcyclohexane-1,2,3-tricarboxylate, on individual methylation followed by hydrolysis, gave the trans,meso-acid (A), identified by comparison with an authentic sample, and the cis,trans-form (B) whose structure and configuration were proved by comparison with a specimen obtained by the unambiguous and highly stereoselective second synthesis. This demonstrated that methylation of the triester isomers occurs stereospecifically and exclusively at C-3. In the second sequence, it has been possible to assign definite conformations to four key intermediates and the final product, directly from n.m.r. spectra, from changes in these spectra accompanying specific steps, and from chemical evidence. Comparison of the n.m.r. spectra of the isomeric triesters (A) and (B) has provided unequivocal proof of the accepted trans,meso configuration for the abietic acid degradation product (A).

Structure of abnormal products isolated from the isomerization of 7-methoxychromano3,4-disoxazole - A novel synthesis of one of the products

A one-step synthesis of (IIb), an isomerization product of 7-methoxychromano3,4-disoxazole, from (III) is reported.

Nitrosation of N,N′-ethylenebis-(acetylacetoneimine) complexes of copper (II) and nickel(II) and characterization of the products

Isonitroso derivatives of copper(II) and nickel(II) complexes of N,N′-ethylenebis(acetylacetoneimine) have been prepared by nitrosation of the respective complexes using nitric oxide as well as nitrite ion. The condensation of isonitrosoacetylacetone in the presence and in the absence of nickel(II) has been investigated. The i.r. and electronic spectra and magnetic moment of the nickel(II) and copper(II) complexes have been studied. The nature of bonding of the ligand to the metal ion is discussed. The complexes have planar structures.

Steroids and related natural products. VIII. Synthesis of oxasteroids

Peroxydisulfuric acid oxidation of testosterone propionate, progesterone, and cholest-4-en-3-one has been shown to yield 3-oxo-17β-hydroxy-4-oxa-5α-androstane (I, after saponification), 3,20-dioxo-4-oxa-5α-pregnane (V) and 3-oxo-4-oxa-5α-cholestane (VII) respectively. Boron trifluoride etherate-lithium aluminum hydride reduction of δ-lactones I, V, and VII led to the corresponding tetrahydropyran derivatives (IIb, VIa, and VIII). Similar reduction of 3β-hydroxy-17-oxo-17a-oxa-D-homo-5α-androstane (XI) gave 3β-hydroxy-17a-oxa-D-homo-5α-androstane (XIIa). Diborane-boron trifluoride etherate was also found to reduce lactones to cyclic ethers, while reduction with diborane gave hemiacetals. Evidence in support of the structures and stereochemistry assigned to the lactones and their unusual reduction products has been summarized. A tentative mechanism is proposed for lactone → ether reduction employing diborane-boron trifluoride etherate.

Steroids and related natural products. VII. Boron trifluoride etherate-lithium aluminum hydride reduction of smilagenin acetate

Reduction of smilagenin acetate (Va) using a boron trifluoride etherate-lithium aluminum hydride reagent, followed by hydrogen peroxide oxidation and acetylation, was found to yield: 3β-ethoxysmilagenin (Vb), 3β-ethoxydihydrosmilagenin acetate (VIa), dihydrosmilagenin diacetate (VIb), and a complex mixture of partially acetylated products. Similar reaction conditions were employed to convert dihydrodiosgenin (II) to dihydrochlorogenin (III). Boron trifluoride etherate-lithium aluminum hydride reduction of 3β-acetoxy-5α-cholestane and 3β-acetoxy-5α-lanostane (VIIIa) was shown to yield the corresponding 3β-ethoxy (e.g., VIIIb) derivatives.