Study on dynamic needle thread tensions in a single needle lock stitch (SNLS) sewing machine. II. Effect of sewing speed,thickness of fabric plies,thread linear density and pre-tensions of threads     

R. S. Rengasamy  D. Samuel Wesley 《Fibers and Polymers》2014,15(8):1773-1778

This paper reports on the effect of pre-tensions on needle and bobbin threads, sewing speed, thickness of fabric plies and the linear density of the threads on the tension peaks occurring on needle thread during sewing on a single needle lock stitch machine. The needle thread tensions are measured at two locations: above the needle bar (bottom segment) and above the needle thread tensioner (top segment). A factorial design approach is used to study the four parameters. The role of bobbin tension is studied in a separate experiment, while keeping the pre-tension on the needle thread constant. The highest tension observed on the needle thread is the stitch tightening tension which is directly affected by the pre-tension set on the needle thread disc tensioner. Heavier threads develop lower tightening tension which may affect the seam balance. The thickness of fabric plies does not affect the needle thread tension. Sewing speed has marginal influence on the stitch tightening tension near the needle thread tensioner. The pre-tension on the bobbin thread affects only the needle thread tension when the take up lever pulls up the needle thread loop to release it from the rotary shuttle hook gib.  相似文献   

Assessing agricultural education: Agricultural economics at a crossroads     

E. Wesley F. Peterson  Fred J. Ruppel  Daniel I. Padberg 《Agriculture and Human Values》1988,5(4):26-33

Colleges of agriculture are being forced to adapt to a changing world. The forces behind these changes affect all departments within the college. In this paper, the place of agricultural economics within the college and within the university is identified, the current situation facing the discipline is outlined, and strategies for responding to the forces of change are discussed. Three alternatives are available: continuation, termination, and metamorphosis. Different departments are likely to pursue different strategies. Some may disappear altogether or may be absorbed into the parent discipline, economics, or into the business school. Other departments may transform themselves into specialized sub-disciplines, such as natural resources or agribusiness departments. Still others may continue with little or no change. Whatever course is followed, strategic planning will surely be necessary.  相似文献   

Insect antifeedant activity of tetranortriterpenoids from the Rutales. A perusal of structural relations     

Suresh G  Gopalakrishnan G  Wesley SD  Pradeep Singh ND  Malathi R  Rajan SS 《Journal of agricultural and food chemistry》2002,50(16):4484-4490

Structure-related insect antifeedant relationship of 56 limonoids (both natural and modified) from the plants belonging to the order Rutales was attempted considering substitution patterns, oxidation states, and hydrophobicity, as well as distant geometry derived through conformational analysis on molecular modeling. Orientation of the furan and hydroxylation at specific carbon sites have been shown to influence the antifeedancy against the fall armyworm, Spodoptera litura.  相似文献   

Differences in acid tolerance during the early life stages of three strains of brook trout,Salvelinus fontinalis     

Geoffrey V. Hurley  Timothy P. Foyle  Wesley J. White 《Water, air, and soil pollution》1989,46(1-4):387-398

Brook trout, Salvelinus fontinalis, embryos and fry from three sources (an acidic watershed in Kejimkujik Park at pH 4.7 to 5.3, a neutral watershed at pH 7, a hatchery at pH 7) were exposed separately to lethal and sublethal levels of acidity (pH 7.0, 5.2, 4.7, 4.3, 3.9), beginning at fertilization. Significant differences in mortality between the strains at low pH were observed and these suggested a genetic component to acid tolerance. Mortality in the strain from the acidic watershed was the lowest, followed by the second wild strain. Survival in both wild strains at low pH was much better than survival in hatchery embryos. These differences in survival at sublethal acidity (4.7 to 7.0) were principally the result of high mortality shortly after fertilization. After this period, survival stabilized. Only at pH 4.3 did substantial mortality occur at hatching. The early embryonic stage therefore appears to be the most susceptible to sublethal acid stress in brook trout. Hatchery strain embryos were also introduced at the eyed stage at 213 degree-days. Subsequent survival of this group was better at low pH than that of hatchery embryos introduced at fertilization, thereby indicating an early or cumulative deleterious effect. Higher acidity retarded hatch in all cases. The time to 50% hatch was delayed by 1.2 degree-days with each increase of 1 μM H⁺.  相似文献   

Insecticidal components from field pea extracts: sequences of some variants of pea albumin 1b     

Taylor WG  Sutherland DH  Olson DJ  Ross AR  Fields PG 《Journal of agricultural and food chemistry》2004,52(25):7499-7506

Methanol soluble insecticidal peptides with masses of 3752, 3757, and 3805 Da, isolated from crude extracts (C8 extracts) derived from the protein-enriched flour of commercial field peas [Pisum sativum (L.)], were purified by reversed phase chromatography and, after reduction and alkylation, were sequenced by matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry with the aid of various peptidases. These major peptides were variants of pea albumin 1b (PA1b) with methionine sulfoxide rather than methionine at position 12. Peptide 3752 showed additional variations at positions 29 (valine for isoleucine) and 34 (histidine for asparagine). A minor, 37 amino acid peptide with a molecular mass of 3788 Da was also sequenced and differed from a known PA1b variant at positions 1, 25, and 31. Sequence variants of PA1b with their molecular masses were compiled, and variants that matched the accurate masses of the experimental peptides were used to narrow the search. MALDI postsource decay experiments on pronase fragments helped to confirm the sequences. Whole and dehulled field peas gave insecticidal C8 extracts in the laboratory that were enriched in peptides with masses of 3736, 3741, and 3789 Da, as determined by high-performance liquid chromatography (HPLC) and electrospray ionization mass spectrometry. It was therefore concluded that oxidation of the methionine residues to methionine sulfoxide occurred primarily during the processing of dehulled peas in a mill.  相似文献   

MAGNESIUM DEFICIENCY IN CHESTNUT GROVES: THE INFLUENCE OF SOIL MANGANESE     

Ester Portela  Carlos Coelho Pires  José Louzada 《Journal of plant nutrition》2013,36(3):452-460

In northeastern Portugal, it has been difficult to identify the threshold value of exchangeable magnesium (Mg) below which Mg deficiency occurs in chestnuts (Castanea sativa Mill.), since discrepancies have been observed in some areas, apparently associated with parent material. A regional survey was carried out in chestnut groves established in soils derived from bedrock of several geological formations, some of them rich in manganese (Mn). Leaf sampling and soil analysis were performed in 38 groves. The lowest value of foliar Mg concentration under good growing conditions was 1.8 g kg^?1 and the highest value in trees with Mg deficiency symptoms was 1.5 g kg^?1. Under acidic soil conditions higher levels of extractable Mn propitiate Mg deficiency. The soils need to reach higher exchangeable Mg (≥0.34 cmolc kg^?1) in order to supply Mg. For lower values of extractable Mn, the deficiency appears when exchangeable Mg is <0.20 cmolc kg^?1 of soil.  相似文献   

Growth and nutrient and nitrate accumulation of lettuce under different regimes of nitrogen fertilization     

Omid R. Zandvakili  Masoud Hashemi  Fatemeh Etemadi  Wesley R. Autio  Sarah Weis 《Journal of plant nutrition》2013,36(14):1575-1593

Abstract

For plant growth and composition, the effects of fertilizers including blood meal (BLO), cottonseed meal (CSM), dehydrated cow manure (COW), and urea (UREA) factored with lettuce (Lactuca sativa L.) of different morphological phenotypes including iceberg, romaine, loose head, and loose leaf were studied in a greenhouse. Lettuce growth increased with increasing nitrogen (N) applications from 0 to 800?mg N/pot (kg), but the top application of BLO, CSM, or UREA suppressed yields. Lettuce grown with BLO, CSM, or UREA had higher concentrations of N than with COW. Nitrate-N concentration in leaves of all varieties exceeded some standards at high application of organic fertilizer or urea except for COW. In general, increasing N application resulted in higher concentration of NH₄-N in lettuce with increases in applications of fertilizers. Organic fertilizers and urea were equally effective in supporting growth and affecting nutrient accumulation in lettuce if sufficient N was supplied.  相似文献   

Influences of Thinning,Chipping, and Fire on Understory Vegetation in a Sierran Mixed Conifer Stand     

Roger F. Walker  Robert M. Fecko  Wesley B. Frederick  Watkins W. Miller  Dale W. Johnson 《Journal of Sustainable Forestry》2013,32(6):493-517

Thinning implemented with a cut-to-length harvesting system coupled with on-site slash chipping and redistribution and followed by prescribed underburning were assessed for their impacts on a shrub understory in an uneven-aged Sierra Nevada mixed conifer stand. Overstory species consisted of California white fir (Abies concolor var. lowiana [Gord.] Lemm.), Jeffrey pine (Pinus jeffreyi Grev. & Balf.), sugar pine (Pinus lambertiana Dougl.), incense-cedar (Libocedrus decurrens Torr.), and red fir (Abies magnifica A. Murr.), while huckleberry oak (Quercus vacciniifolia Kellogg) was predominant among 10 understory shrubs. Herbaceous species were entirely absent from the site for the 4-yr duration of the study. The mechanized treatments exerted minimal detriment effects on overall understory cover and weight, and for prostrate ceanothus (Ceanothus prostratus Benth.) and creeping snowberry (Symphoricarpos mollis Nutt.)—two of the lesser shrubs—were stimulatory. In contrast, losses to the total understory from the underburn amounted to two-thirds of cover and weight in the absence of the mechanized treatments and more than three-quarters where they had been implemented, with huckleberry oak prevalence especially diminished. For almost all of the understory species individually as well as for the total, greater pretreatment abundance predisposed greater posttreatment prevalence. Results of this study provide insight into the understory impacts of restoration treatments that are deemed especially appropriate for sensitive sites in western U.S. forests.  相似文献   

Lethal temperature for pinewood nematode, Bursaphelenchus xylophilus, in infested wood using radio frequency (RF) energy     

Adnan Uzunovic  Brad Gething  Aaron Coelho  Angela Dale  John J. Janowiak  Ron Mack  Kelli Hoover 《Journal of Wood Science》2013,59(2):160-170

We evaluated radio frequency (RF) dielectric heating for eradication of pinewood nematodes (PWN) in infested wood. Thirteen temperatures were tested (from ambient to 70 °C) on small wood samples (2.5 × 3.8 × 0.64 cm) to determine the minimum lethal temperature (100 % mortality), which was 56 °C [based on infra-red (IR) thermal images data 55.5–57.4 °C] with a 1 min hold time. We also used thermal probes inside the wood to confirm that temperatures were ≥56 °C. Thirty additional samples were tested bracketing the minimum lethal temperature using 54, 56 and 58 °C with additional replications to produce the minimum sample size equivalent of 100 % mortality of at least 93,616 nematodes to satisfy the Probit 9 efficacy requirement. This minimum lethal temperature was further verified by treating infested large wood blocks (10.2 × 10.2 × 25.4 cm). All samples that met or exceeded the 56 °C lethal temperature for the required 1 min hold time (as measured by probes inserted in the wood and on the wood surface by IR) produced 100 % mortality. The sample size required to show Probit 9 efficacy was also satisfied. This study supports the consideration of RF in addition to microwave (MW) dielectric heating as alternative treatments of wood packaging material for inclusion in ISPM No. 15, provided the treatment delivers the target lethal temperature throughout the profile of the material in industrial scale operations.  相似文献   

Cerebellar cortical abiotrophy in Wiltshire sheep     

AC Johnstone  CB Johnson  KE Malcolm  RD Jolly 《New Zealand veterinary journal》2013,61(4):242-245

AIM: To investigate the nature of a neurological disease in Wiltshire sheep.

METHODS: Three affected lambs were examined, humanely killed and necropsied. Selected neurological tissues were examined by light and electron microscopy.

RESULTS: Primary neurological lesions were confined to the cerebellum and were characterised by loss of Purkinje cells and the presence of large hypertrophied dendrites of surviving Purkinje cells. These contained stacks of smooth endoplasmic reticulum. There was hyperplasia and cell swelling of Bergmann glia. Mild Wallerian-type degeneration affected white matter in the cerebellum and spinal cord.

CONCLUSION: The cerebellar lesions were of a degenerative and reactive rather than hypoplastic nature. These, and the history, suggest a genetic cause with putative inheritance as an autosomal recessive trait. Accordingly, the disorder is described as a cerebellar abiotrophy.  相似文献