Permeability to water of the wood cell wall and its variation with temperature     

M. Anne Palin  J. A. Petty 《Wood Science and Technology》1983,17(3):187-193

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The relationship between the axial permeability of wood to dry air and to a non-polar solvent     

A. J. Bolton  J. A. Petty 《Wood Science and Technology》1978,12(2):111-126

Summary The different approaches to the use of steady-state gas flow data in the prediction of the steady-state axial permeability of wood to liquids are reviewed. Since these may be shown to have certain theoretical shortcomings, a new predictive method based on a computer analysis is presented. This and previous methods are tested experimentally; apparently, none can be relied upon to predict the liquid permeability accurately. However, it is clear that the true liquid permeability is not measured; the reasons for this are uncertain. Until this difficulty is resolved, the precision of predictive methods cannot be accurately assessed.The authors wish to acknowledge the encouragement of Professors Matthews and Roche. This work was supported in part by a Research Grant from the Science Research Council, and was carried out while A. J. Bolton was holder of a Science Research Council Studentship.  相似文献   

Pet fish care and husbandry.     

Barbara D Petty  Ruth Francis-Floyd 《Veterinary Clinics of North America: Exotic Animal Practice》2004,7(2):397-419, vii

This article guides the technician through the basic principles of fish health. Nutrition, including the proper storage of fish foods, is discussed,as are the varying dietary needs of fish. The ability to recognize water-quality problems is emphasized, especially the conditions that commonly result in high mortality. Collection of specimens for microscopic examination or other diagnostic tests is explained.  相似文献   

Pregnancy detection and the effects of age, body weight, and previous reproductive performance on pregnancy status and weaning rates of farmed fallow deer (Dama dama)     

Willard ST  Petty SJ  Sasser RG  White DL  Randel RD 《Journal of animal science》1999,77(1):32-38

Fallow does (n = 502) of different ages (mature, 2-yr-old, and yearling) were maintained with bucks for a 60-d breeding season to determine whether previous reproductive performance and changes in BW affect doe pregnancy rates and to compare the effectiveness of ultrasonography and serum pregnancy-specific protein B (PSPB) for the detection of pregnancy in fallow does. Ultrasonography was performed, blood samples collected, and BW recorded at buck removal (d 0) and at 30 and 90 d after buck removal. Lactational status (lactating = WET; nonlactating = DRY) were determined from farm records taken at weaning prior to each breeding season (autumn 1990 through autumn 1994). Ultrasonography and PSPB for determining pregnancy were in agreement 93% of the time. Overall pregnancy rates did not differ (P>.10) relative to age of the doe; the combined pregnancy rate was 92%. We also determined that 82.9% of does conceived early in the breeding season and that the incidence of embryonal-fetal mortality during the first 90 d after buck removal was 2.8%. In general, mature and 2-yr-old DRY does were heavier and had lower pregnancy rates than WET does. The overall weaning rate for all does was 77.9%. Loss in the number of fawns from pregnancy detection to weaning was equivalent to 14.8% for mature does, 24.7% for 2 yr old does, and 42.5% for yearling does. These data indicate that even though pregnancy rates were relatively high, further study is needed to determine the causes associated with subsequent fawn losses, particularly among yearling does. As a production tool, lactational WET/ DRY status testing was found to be an acceptable means for determining the reproductive potential of individual does within the herd. In addition, serum PSPB may be used in place of ultrasonography for pregnancy diagnosis in fallow deer as early as d 30 after buck removal.  相似文献   

What is your diagnosis? Musculoskeletal neoplasia     

Lori D  Toppin DS  Lori JP 《Journal of the American Veterinary Medical Association》2010,237(10):1131-1132

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Allotransplantation of Transgenic Mouse Ovaries Expressing Enhanced Green Fluorescent Protein under the Control of the Murine Phosphoglycerate Kinase 1 Promoter     

HT Wu  CK Chou  YC Hung  CK Yu 《Reproduction in domestic animals》2010,45(5):900-906

The aim of this study was to generate a transgenic mouse that ubiquitously expressed enhanced green fluorescent protein (EGFP) under the control of the murine phosphoglycerate kinase 1 promoter by allotransplantation of transgenic mouse ovaries. The EGFP transgenic mice expressed green fluorescence in many organs, and the fluorescence was detected as early as the embryonic stage. Ovaries from the EGFP transgenic mice were allotransplanted into recipients and these mice were mated with normal male mice. Histological sections of EGFP‐allotransplanted ovaries from the recipient mice showed the well development and formation at follicles and corpora lutea. The green fluorescence was clearly detectable at the allotransplanted section of the ovaries, which had fused with the normal ovary. The average size of the first litter from these mice was 6.8 ± 1.2 pups per recipient, and 17.8% of the pups expressed EGFP. These results demonstrated that allotransplantation of transgenic ovaries can restore a normal reproductive lifespan and can be used to generate a ubiquitously expressing EGFP animal model.  相似文献   

Laminar flow of fluids through short capillaries in conifer wood     

J. A. Petty 《Wood Science and Technology》1974,8(4):275-282

Summary The viscous and slip flow terms of the Hanks-Weissberg and Petty-Puritch gas flow equations are compared. A Couette correction of 3/8 x radius must be added to the capillary length in the viscous term of the latter equation. The slip flow terms in the two equations are equivalent to within ±10%. A modified method is presented for calculating the radius and number of short capillaries from gas flow measurements. The applicability of this method was confirmed by measurements of gas flow through artificial membranes containing short capillaries. Earlier published values for the number and radius of pit membrane pores are recalculated using the modified method. The possible effects of very close spacing of pores in a membrane are discussed and it is suggested that the Couette correction is probably still applicable in this case.This work was supported in part by a Research Grant from the Science Research Council.  相似文献   

Book reviews     

J. A. Petty 《Wood Science and Technology》1984,18(4):266-254

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Permeability to water of the cell wall material of spruce heartwood     

M. Anne Palin  J. A. Petty 《Wood Science and Technology》1981,15(3):161-169

Summary The permeability to water of spruce heartwood has been measured by applying a known osmotic pressure difference across specimens in which the cell walls were water swollen and most of the void space was filled with paraffin wax. To ensure that solute molecules should not penetrate the cell wall aqueous solutions of polyethylene glycol of molecular weight 6,000 and dextran of molecular weight 40,000 were used to generate the osmotic pressures. The mean values of the permeability k×10²¹ defined by the Darcy equation were 67.5 m² for longitudinal flow, 7.12 m² for radial flow and 4.03 m² for tangential flow. Permeability was probably overestimated by about 10% owing to water entering some of the void space not filled by wax. The measured values are 10 to 100 times smaller than those calculated assuming all water in the cell walls is free to flow and this is probably caused by much of the water being bound to cell wall material. This work was made possible by Research Grants from the Leverhulme Trust Fund and the Science Research Council, and we thank both organisations for their support. We wish to thank Hickson's Timber Products Ltd for kindly supplying some of the specimen holders and Professor J. D. Matthews for his encouragement of this work Paper presented at the Seminar on “Flow and Permeability in Wood” of the Royal Microscopical Society, Wood Anatomy Group, held in Princes Risborough, 17, October 1979  相似文献   

Effect of Transgene Introduction and Recloning on Efficiency of Porcine Transgenic Cloned Embryo Production In Vitro     

SJ Uhm  MK Gupta  ZC Das  JH Kim  C Park  T Kim  HT Lee 《Reproduction in domestic animals》2009,44(1):106-115

Retrovirus-mediated exogenous gene transfection of somatic cells is an efficient method to produce transgenic embryos by somatic cell nuclear transfer (SCNT). This study evaluated whether efficiency of transgenic embryos production, by SCNT using fibroblast cells transfected by retrovirus vector, is influenced by the introduced transgene and whether recloning could further improve its efficiency. Transgenic cloned embryos were produced by SCNT of porcine foetal fibroblast cells transfected by either LNβ-Z or LNβ-enhanced green fluorescent protein (EGFP) retrovirus vector and evaluated for their developmental ability in vitro . Blastomeres from four-cell stage porcine embryos, produced by SCNT of foetal fibroblast cells transfected with LNβ-EGFP retroviral vector, were subsequently recloned into enucleated metaphase II oocytes and evaluated for changes in chromatin configuration, in vitro embryo development and gene expression. Analysis of results showed that cleavage and blastocyst rates of porcine SCNT embryos, using LacZ (53.6 ± 6.4%; 12.0 ± 5.7%) or EGFP (57.5 ± 6.3%; 10.1 ± 4.1%) transfected fibroblasts, did not differ (p > 0.05) from those of non-transfected controls (60.9 ± 8.2%; 12.3 ± 4.0%). Recloning of blastomeres did not further improve the in vitro development rate. Interestingly, the nuclei of blastomere underwent slower remodelling process than somatic cell nuclei. Both cloned and recloned embryos showed 100% transgene expression and there were no evidence of mosaicism. In conclusion, our data shows that the efficiency of transgenic cloned embryos production by SCNT of somatic cells transfected with replication-defective retrovirus vector is not influenced by the transgene introduction into donor cells and recloning of four-cell stage blastomere could not further improve its efficiency.  相似文献