摘要:

AbstractThe extent to which tannin extract production is itself an agricultural operation is indicated and the distribution of tannins in the plant kingdom discussed. Present knowledge of the nature of the tannins is summarized and illustrated, by reference to specific extracts. The problem of the biological origin and function of tannins is discussed, particular reference being made to the effect of these substances on viruses. Brief mention is made of the effect of tannins on soils which they may disperse or aggregate to a marked extent.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740080702

出版商:John Wiley&Sons, Ltd    

年代:1957

数据来源: WILEY

ISSN:0022-5142    

DOI:10.1002/jsfa.2740080703

出版商:John Wiley&Sons, Ltd    

年代:1957

数据来源: WILEY

摘要:

AbstractSoils of the podzol group are characterized by the translocation of iron compounds down the profile; it is considered that the ferric oxide in the uppermost horizons of the soil is mobilized by the action of soluble organic compounds leached from the overlying tree litter.The solution and reduction of ferric oxide by aqueous leaf extracts is apparently caused by the joint action of carboxylic acids and polyphenols.The development of a horizon of clay accumulation is a feature of certain podzolic soils. As aqueous leaf extracts have the property of dispersing clay suspensions, it is apparent that the development of textural profiles could be promoted by the action of these extracts. In the dispersion of clays, polyphenolic compounds constitute one of the chief groups of active compounds.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740080704

出版商:John Wiley&Sons, Ltd    

年代:1957

数据来源: WILEY

ISSN:0022-5142    

DOI:10.1002/jsfa.2740080705

出版商:John Wiley&Sons, Ltd    

年代:1957

数据来源: WILEY

摘要:

AbstractN‐Mono‐ andNN‐disubstituted fluoracetamides have been tested as potential larvicides, contact insecticides and rodenticides.All monosubstituted amides were toxic to larvae ofMusca vicinaMacq. at a concentration of 100 p.p.m. Disubstituted amides were inactive or only slightly active. Only the amides monosubstituted by relatively small aryl radicals (phenyl,p‐tolyl,p‐fluorophenyl andp‐chlorophenyl) showed contact toxicity to adultMusca vicinaMacq. of a strain highly resistant to DDT.All compounds were toxic to laboratory rats. The approximate LD50values were lowest (4 to 8 mg./kg.) forN‐mono‐arylamides with small aryl radicals. Those with larger aryl substituents (α‐ and β‐ naphthyl,p‐diphenylyl andp‐bromophenyl) had somewhat higher LD50values. ThemolarLD50values of theN‐arylamides fall within a narrow range.The possible mode of action of

ISSN:0022-5142    

DOI:10.1002/jsfa.2740080706

出版商:John Wiley&Sons, Ltd    

年代:1957

数据来源: WILEY

摘要:

AbstractA technique has been devised whereby the limiting conditions of equilibrium relative humidity, and consequently of osmotic pressure, for bacterial growth can be demonstrated, using bacteria in thin films. WithSalmonella typhimuriumandEscherichia coliType I, growth is prevented at and below an e.r.h. of 92% and withStaphylococcus aureus, at or below 85%. From the results, it may be deduced that the surface drying that occurs during baking or on exposure of moist foods to normal atmospheres does afford protection against the increase of surface bacterial contamination. The possibility of the production of variants resisting high osmotic pressure cannot be excluded, but no clear evidence of their production was obtained during the present studies.By a modification of the technique, a heterogeneous article of food can be dissected and the vulnerability of the different parts of the growth of bacterial infection can be determined.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740080707

出版商:John Wiley&Sons, Ltd    

年代:1957

数据来源: WILEY

摘要:

AbstractThe fumigant toxicities to the grain weevilCalandra granariaof 39 alkyl chlorides, bromides and thiocyanates have been estimated with considerable accuracy. The difference between toxicities of isomers on the thermodynamic scale is small, except near the cut‐off point, or when instability or chemical reactivity are evident. Near the cut‐off point, the characteristic sudden rise in the ratioPt/Ps(toxic vapour pressure/saturation vapour pressure) is more marked the lower the vapour pressure of the isomers, so that a secondary compound may be toxic when the normal one is non‐toxic. Vapour pressure may also be a limiting factor for a whole series when the saturation vapour pressures of even the lower homologues are small. For chlorides and bromides,Pt/Psvalues change slowly with carbon content below the cut‐off member, but for unit saturation vapour pressure the bromides are the more toxic. When a molecular volume correction factor,V, is introduced, the points for chlorides and bromides form a single line, the slope of which approximates to unity. The equation, logPt/V= logPs+ k′, gave better results than logPt= b logPs+ k, when it was applied to various published data, and experimental evidence was therefore found justifying a mainly theoretically derived equation of McGowan4.Experiments using different times of exposure, and with death as the criterion of toxicity, indicated no difference of behaviour between physical and chemical poisons. Doubling the exposure time approximately halved the LD50and hence thePt/Psvalue. This provides further evidence that the arbitrary physical/chemical barrier ofPt/Ps= 0.05 has little practical sig

ISSN:0022-5142    

DOI:10.1002/jsfa.2740080708

出版商:John Wiley&Sons, Ltd    

年代:1957

数据来源: WILEY

摘要:

AbstractThe water‐soluble carbohydrates, glucose and fructose (reported together as total free hexoses), sucrose and fructosan have been determined in eight strains of rye‐grass of varying rates of growth and in two strains of timothy and one of cocksfoot in their first and second years of growth. In the rye‐grasses, the extremely rapid growth and flowering of annual varieties resulted in much smaller accumulations of fructosan but more free hexoses than in biennial or perennial plants. Flower formation in the timothy grasses in the first year similarly delayed the storage of fructosan until after head emergence.In second‐year growth the fructosan content of all species increased rapidly early in the year but flower formation and early development caused a marked fall in the fructosan content of the timothy and cocksfoot strains but not of the rye‐grasses. The reverse was later true during stem elongation after flower emergence, when the fructosan content in the rye‐grasses fell sharply whilst those of the timothy grasses and cocksfoot rose to a second peak. The practical aspect of this difference in the soluble carbohydrate content of grasses at similar stages of growth i

ISSN:0022-5142    

DOI:10.1002/jsfa.2740080709

出版商:John Wiley&Sons, Ltd    

年代:1957

数据来源: WILEY

摘要:

AbstractDissection of loin mutton chops showed 13.4–17.0% bone, 42.2–48.5% muscle and 38.1–40.8% fatty tissue. In a sample showing fatty degeneration, the muscle tissue was not apparent and the dissection revealed 19.6% bone and 80.4% fatty tissue. In the bone‐free tissues of normal chops 84.2–87.3% of the total fat was concentrated in the fatty tissues. The fatty acid composition of the lipids of the muscle and fatty tissues of the chops was similar to that observed by other investigators for sheep depot and muscle fats. The loin chop muscle lipids contained a somewhat higher proportion, approx. 3%, of C20unsaturated acids as compared with 1% or less usually observed in sheep fats by other investigators. The fat in the fatty tissues contained more stearic acid andtrans‐acids, but less di‐ and polyethenoid acids and particularly tetraenoic (arachidonic) acid than t

ISSN:0022-5142    

DOI:10.1002/jsfa.2740080710

出版商:John Wiley&Sons, Ltd    

年代:1957

数据来源: WILEY

摘要:

AbstractThirty‐five carbocyanines were examined for fungitoxicity and some were found to be active. This newly found biological property was limited to carbocyanines of a fairly low molecular weight, and was dependent on the heterocyclic base or bases from which the carbocyanine was derived. Alkyl substituents enhanced the fungitoxicity of the dyes irrespective of their position. Tests with some dyes showed that these penetrated to the protoplasts of the spores, staining them irreversibl

ISSN:0022-5142    

DOI:10.1002/jsfa.2740080711

出版商:John Wiley&Sons, Ltd    

年代:1957

数据来源: WILEY