• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 11
  • 5
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 25
  • 25
  • 14
  • 6
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Skystųjų preparatų iš Juglans nigra L. lapų gamyba, biologiškai aktyvių junginių kiekio įvertinimas ir antioksidacinio aktyvumo tyrimas / Biologically active compounds and antioxidant activity evaluation of liquid Black walnut (Juglans nigra L.) leaf preparations

Keturakytė, Vytautė 18 June 2014 (has links)
Tyrimo tikslas - pagaminti vandenines ir etanolines ištraukas iš Junglans nigra L. lapų ir įvertinti bendrą fenolinių junginių, bendrą flavonoidų, juglono kiekį bei nustatyti antioksidacinį aktyvumą. Metodika: 1. Tyrimo objektai: 70% etanolinė juodojo riešutmedžio tinktūra, vandeninė juodojo riešutmedžio lapų ištrauka bei gamyklinis “Black Walnut” 1:1 ekstraktas (gamintojas „Nature's Answer”, JAV). 2. Ištraukų iš J. nigra lapų gamyba. 1) Etanolinės tinktūros gamyba. Pritaikius perkoliacijos metodą iš juodojo riešutmedžio lapų žaliavos, naudojant 70% etanolį, buvo pagaminta tinktūra (santykis 1:10). 2) Vandeninė ištrauka. 10 g smulkintos lapų žaliavos buvo užpilta 120 ml verdančio vandens ir kaitinta 1 val. Ištrauka nufiltruota pro 4 nr. Vatmano filtrą. 3. Kokybinės flavonoidų įvertinimo reakcijos. 4. Bendras fenolinių junginių nustatymas naudojant Folin – Ciocalteu metodą (standartas – galo r.) 5. Bendras flavonoidų kiekio nustatymas spektrofotometriniu būdu, naudojant AlCl3 tirpalą (standartas - rutinas). 6. Juglono kiekio nustatymas spektrofotometriniu būdu. 7. Antioksidacinio aktyvumo įvertinimas fluorimetriniu būdu, naudojant 10-acetil-3,7-dihidroksifenoksazinas (AMR) ir krienų peroksidazę (HPR). Rezultatai. Bendram fenolinių junginių, bendram flavonoidų bei juglono išekstrahuoto kiekio palyginimui buvo pagamintos J. nigra lapų etanolinė ir vandeninė ištraukos. Tiriamų objektų biologiškai aktyvių komponentų kiekiai buvo palyginti su gamykliniu „Black Walnut“ ekstraktu... [toliau žr. visą tekstą] / Aim of the work - produce aqueous and ethanolic extracts of Junglans nigra leaves, evaluate the total phenolic and total flavonoids content, juglone concentration and identify antioxidant activity. Methods: 1. Objects of study: ethanolic tincture and aqueous extract of black walnut leaves, “Black Walnut” extract, 1:1 („Nature's Answer”, USA). 2. Liquid preparations of J. nigra leaves production: 1) Ethanolic tincture production. Tincture was produced of black walnut leaves applying the method of percolation. The 70% ethanol was used. Tincture ratio is 1:10. 2) Aqueous exract production. 10 g shredded leaves of black walnut were extracted with 120 ml of boiling wather for 1 hours. After boiling extract was filtered throught the Whatman paper no. 4. 3. Qualitative evaluation of flavonoids. 4. Total phenolic content was determined by spectrophotometric (Folin - Ciocalteau) method. 5. Total flavonoids content was measured with an aluminum chloride colorimetric assay using spectrophotometer. 6. Juglone determination by spectrophotometric method. 7. Fluorimetric antioxidant activity assay by using N-Acetyl-3,7-dihydroxyphenoxazine (Amplex Red) and horseradish peroxidase (HPR). Results. Ethanolic and aqueous extracts of J. nigra leaves were made to compare total phenolic, total flavonoids content, juglone concentration. Biologically active components study results of ethanolic and aqueous extracts were compared with “Black Walnut” extract. The highest total phenolic and total... [to full text]
22

The effects of sugar maple (Acer saccharum Marsh.) and black walnut (Juglans nigra L.) on soil fertility : preliminary assessment of their agroforestry potential

Kipkech, Francis Chepkonga January 1995 (has links)
Two studies were carried out in the Morgan Arboretum of McGill University to explore the agroforestry potential of some native tree species of Southern Quebec. In the first study, soil chemical characteristics under basswood (Tilia americana L.), white ash (Fraxinus americana L.) and bitternut hickory (Carya cordiformis Wang. K. Koch) in relation to sugar maple (Acer saccharum Marsh.) were assessed in natural stands. Soil pH was highest under white ash and was lowest under bitternut hickory. Soil NO$ sb3 sp-$ was low under basswood compared to white ash. Soil pH and exchangeable soil Ca$ sp{2+}$ and Mn$ sp{2+}$ decreased with an increase in basal area and exchangeable soil K$ sp+$ decreased (p = 0.07) with an increase in the proportion of sugar maple relative to total basal area. / In the second study, the effects of black walnut (Juglans nigra L.) on growth and nutrient content of lettuce (Lactuca sativa L.), kale (Brussica oleracea L.), parsley (Petroselinum crispum) and Swiss chard (Beta vulgaris L.) in an alley cropping system were determined. The experiment was carried out in a randomized complete block design with repeated measures. All vegetables survived in the black walnut plantation and in the open field. The order of sensitivity to growth under black walnut was Swiss chard $>$ kale $>$ lettuce $>$ parsley. Low light intensity in the plantation likely decreased plant dry weights and nutrient content. Generally plant N, P and K concentrations were higher in the plantation while Ca, Mg and Mn concentrations were higher in the open field, possibly due to an antagonistic effect of high soil K$ sp+$ content in the plantation and to inhibitory effects of black walnut.
23

Comparison of aluminum mordanted and nonmordanted wool yarns naturally dyed with Kansas black walnut, Osage orange, and eastern redcedar sawdust

Doty, Kelsie January 1900 (has links)
Master of Science / Apparel, Textiles, and Interior Design / Sherry J. Haar / This study compared the colorfastness of potassium aluminum sulfate (PAS) mordanted and nonmordanted 30/2 wool yarn, dyed with black walnut (Juglans Nigra), Osage orange (Maclura pomifera), and eastern redcedar (Juniperus virginiana) sawdust. Information from this study is intended to inform natural dye artisans and to increase the profitability of sawdust for farmers, ranchers, and mill owners who would otherwise find little use for this byproduct of timber manufacturing. Pre-testing ensured dyeings of visually comparable color depth and dye concentrations were pre-tested to find a standard depth of shade between the same dye on PAS mordanted and nonmordanted wool yarns. Tests for colorfastness to light, laundering and staining were performed in accordance to AATCC test methods. Resulting colors for exposed and unexposed specimens were rated using CIE L* a* b* values and AATCC gray scale for color change. GLM Anovas and two-sample t-tests were used to statistically analyze CIE L* a* b* values. As expected, findings indicated that dye absorption was improved with the use of a PAS mordant, especially for black walnut and eastern redcedar. For yarns premordanted with PAS the dyewoods became yellower. A PAS mordant slightly improved colorfastness to light for black walnut and eastern redcedar, but did not influence Osage orange which had an unexpected color change from bright yellow to warm brown after exposure to light. Colorfastness to laundering was slightly improved with PAS for Osage orange, while black walnut and eastern red cedar had slightly less color change without the mordant. This research was supported by the Agricultural Research Experiment Station and Kansas State University.
24

The effects of sugar maple (Acer saccharum Marsh.) and black walnut (Juglans nigra L.) on soil fertility : preliminary assessment of their agroforestry potential

Kipkech, Francis Chepkonga January 1995 (has links)
No description available.
25

<b>HYPERSPECTRAL CHARACTERIZATION OF FOREST HEALTH</b>

Sylvia Park (19203892) 26 July 2024 (has links)
<p dir="ltr">Reflectance spectroscopy has been increasingly used in forestry due to its ability to rapidly, efficiently, and non-destructively detect tree stress, enabling timely and cost-effective forest management decisions. This dissertation synthesizes three studies and five experiments to understand and improve our ability to use spectral data to estimate a variety of foliar physiochemical traits and identify spectral responses in multi-stress environments, thus, advancing our understanding and application of hyperspectral data in forest management.</p><p dir="ltr">The first study seeks to refine the hyperspectral approach to monitoring tree stress by selecting optimal wavelength ranges to enhance the estimation of foliar traits, such as CO<sub>2</sub> assimilation rate, specific leaf area, leaf water content, and concentrations of foliar nitrogen, sugars, and gallic acid. The study revealed that model performance varied significantly across the different wavelength ranges tested and consistently, including longer wavelength regions improved trait estimation for all traits modeled. This research also established a framework for discovering novel or previously unknown absorption features associated with functional traits, thereby laying the groundwork for expanded spectral applications. This advancement enables the estimation of diverse foliar traits and facilitates detailed stress detection in trees.</p><p dir="ltr">The second study focuses on assessing the effectiveness of hyperspectral data in estimating foliar functional trait responses to various biotic and abiotic stressors and to differentiate those stressors in black walnut (<i>Juglans nigra </i>L.) and red oak (<i>Quercus rubra</i> L.) seedlings. We demonstrated that spectral data can reliably estimate a wide range of foliar traits, highlighting its potential as a surrogate for reference data in understanding plant responses to stress. This research revealed that spectral leaf predictions can effectively provide stress-specific insights into tree physiochemical responses to biotic and abiotic stressors.</p><p dir="ltr">The third study explores the application of hyperspectral reflectance to identify drought-induced foliar responses in black walnut seedlings during their initial field establishment. Chemometric models developed from greenhouse experiments were applied to spectral data collected in the field to assess their transferability and accuracy in predicting various leaf traits under drought stress. Using only spectral data, we demonstrated that seedlings show distinct spectral responses to past and ongoing drought stress, with varying degrees depending on seed provenances. This research aims to provide practical insights for utilizing spectral analysis in real-world conditions and understanding the challenges of using spectral tools in the field.</p><p dir="ltr">Collectively, this dissertation demonstrates the robust potential of hyperspectral reflectance technology in advancing the monitoring of tree health. By optimizing spectral range selection, reliably estimating tree foliar traits under stress conditions, differentiating various stressors in controlled environments, and effectively detecting current and past drought stress in field conditions, this research offers valuable insights for improving forest health monitoring and management strategies in response to environmental challenges.</p>

Page generated in 0.0319 seconds