467 research outputs found
Outils et évaluation Actes du congrès de l’Actualité de la recherce en éducation et en formation (AREF
No full textThe effects of light intensity on seed germination and seedling growth of cassia fistula (linn.), enterolobium saman (jacq.) Prain ex king. And delonix
No full textThe present study investigated the effect of 100, 50 , and 25 % light intensities
on seed germination and early seedling development of Cassia fistula, Enterolobium
saman and Delonix regia. The experiment was carried out under temperature of 25°C
- 15°C day and night and 65 % relative humidity, in the greenhouse. One hundred
percent light intensity significantly produced the highest seed germination and
seedling growth of the three species for all growth characteristics measured. Fifty
percent light intensity treatment produced seed germination and seedling growth to
come in the second order and, sometimes, shared full light intensity treatment. The
growth characteristics of Delonix regia seedlings had almost the highest values
among species and in full light intensity treatment. Although Cassia fistula seedlings
had lower growth, in comparison with the other two species, however, they tolerated
low light intensity and had the highest survival and root growth.Corresponding Author:
Prof. Ibrahim Mohammed Aref
Plant Production Department, College of Agriculture, King Saud University, P.O. Box 2460 Riyadh 11451, Saudi Arabia.
Email: [email protected]
Effects of pre-germination treatments and sowing depths upon germination potential of some Acacia species
No full textSeeds of Acacia farnesiana (L.) Willd., A. salicina Lindley, A.
nilotica (L.) Willd. ex Del., A. ehrenbergiana Hayne, A. seyal Del., A.
saligna (Labill.) H. L. Wendl. and A. tortilis (Forssk.) Hayne were
subjected to pre-germination treatment. This was either by soaking
seeds in water for 24 or 48 or 72 hours or by placing them in boiling
water and left them to cool to the room temperature. All seeds were
sowed either at 2 or 4 or 6-cm at soil. The higher germination
percentage for all Acacia species was obtained after boiling seeds in
water and at 2-cm sowing depth apart from A. ehrenbergiana. It
showed no response to boiling in water but had the best result with
soaking in water for 24h. The results of this study suggest that boiling
seeds of the investigated Acacia species in water is recommended with
sowing depth not deeper than 4 cm.Corresponding Author:
Dr. Ibrahim Mohammed Aref
Department of Plant Production, College of Agriculture, King Saud University,
P. O. Box 2460 Riyadh 11451, Saudi Arabia
Email: [email protected]
Performance of Leucaena leucocephala and Albizia lebbeck trees under low irrigation water in the field
No full textGrowth of Leucaena leucocephala and Albizia lebbeck trees was investigated under
low water supply in the field using a complete randomized block design at the
Research and Experiments Station of the College of Food Science and Agriculture,
Riyadh, Saudi Arabia. The trees were irrigated at either 160 (well water supply) or
500 mm (low water supply) of a class "A" evaporation-pan records for two years.
Differences were occurred between L. leucocephala and A. lebbeck trees across
irrigation treatments with greater values for L. leucocephala in most of the growth
characteristics measured. Comparing with L. leucocephala, leaves of A. lebbeck
comprises only small proportion of the total weight of tree while allocated equal
proportions to their branches and roots (41%).while L. leucocephala trees allocated
almost similar proportions to their branches, stem and roots (27-28%). Low water
supply decreased stem by 19.5% with stem diameter was unaffected. Leaf, branches,
stem, root and consequently total dry weight of the trees decreases by 42, 51.5, 45, 51
and 94% in low water supply. However, the performance of L. leucocephala and A.
lebbeck trees endured low irrigation conditions in terms of survival and maintaining
reasonable growth.Corresponding Author:
Prof. Ibrahim Mohammed Aref
Plant Production Department, College of Food Science and Agriculture, King Saud University, P.O. Box 2460 Riyadh 11451 Saudi Arabia.
Email: [email protected]
Some lower bounds for the quotients of normalized error function and their partial sums
No full textsummary:The purpose of the present paper is to determine lower bounds for , and , where is the generalized normalized error function of the form and its partial sum. Furthermore, we give lower bounds for and , where is the Alexander transform of . Several examples of the main results are also considered
Fonksiyonel nanomalzemelerin üretimi için kendiliğinden düzenlenen peptitlerin tasarım ve sentezi
No full textCataloged from PDF version of article.Includes bibliographical references (leaves 146-171).Self-assembling peptides are a class of supramolecular polymers, which exploit noncovalent interactions such as hydrogen bonding, hydrophobic, electrostatic, charge-transfer complex, π-π, and van der Waals interactions to generate well-defined supramolecular nanostructures including nanospheres, nanosheets, nanotubes, and nanofibers. These versatile peptide-based supramolecular nanomaterials have been utilized in variety of applications including catalysis, sensing, light harvesting, optoelectronic, bioelectronic and tissue engineering. In this thesis, use of supramolecular peptide nanofibers formed by specially designed short peptide sequences that can form sheet-like hydrogen bonded structures for controlled synthesis of nanometer scale functional materials were explored. Specifically, n-type and p-type β-sheet forming short peptide sequences were synthesized, which assemble separately into well-ordered nanofibers in aqueous media. These p-type and n-type nanofibers coassemble via hydrogen bonding and electrostatic interactions to generate highly uniform supramolecular n/p-coassembled 1D nanowires. This smart molecular design ensures alternating arrangement of D and A chromophores within n/p-coassembled supramolecular nanowires. Supramolecular n/p- coassembled nanowires were found to be formed by alternating A-D-A unit cells having an association constant of (KA) of 5 x 105 M-1. Moreover, I designed and synthesized β-sheet forming peptide nanofibers to fabricate different metal and metal oxide nanostructures in highly controlled manner using wet chemistry and atomic layer deposition techniques. These hybrid organic-inorganic nanostructures were employed in model Suzuki coupling, alkyne-azide cycloaddition and hydrolysis of ammonia borane reactions.by Mohammad Aref Khalily
Bvg status of <i>B</i>. <i>pertussis</i> bacteria at time of harvest affects protein composition of the resulting wP vaccines.
No full textAmounts of proteins (A) and LPS (B) present in wP vaccines Aref, B, C, D, E (harvested 0, 2, 6, 12, 24 hours after the addition of sulfate, respectively) derived from three individual B. pertussis culture runs were measured by ELISA using specific monoclonal antibodies directed against individual proteins or LPS. (C) Fatty acid composition of vaccines Aref, B, C, D, and E analysed using a modified gas chromatography method (in duplicate). The black lines indicate the background levels measured in PBS only by ELISA. * = p < 0.05.</p
Geostatistical Structural Analysis: Exploring, Fitting and Testing Semivariograms
No full textIn conclusion, interactive tools and two alternative techniques (median polish with grid rotation and nonnested hypotheses tests) are available to researchers doing geostatistical structural analysis.Made available in DSpace on 2015-09-25T22:33:39Z (GMT). No. of bitstreams: 2
license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5)
9912247.pdf: 10225843 bytes, checksum: f22b2c5e6dfea34f1bcef626ba6688a8 (MD5)
Previous issue date: 1998Embargo set by: Seth Robbins for item 86338
Lift date: Forever
Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDsRestricted to the U of I community idenfinitely during batch ingest of legacy ETDsU of I Only257 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1998
Nanotechnology Applied to Stem Cell-Substratum Interactions
No full textThe modulation of biological interaction with artificial surfaces is a vital aspect of
biomaterials research. Perhaps the most challenging area is transplantation involving the
introduction of stem cells into the body with their ability to differentiate; the response of
stem cells to implanted biomaterials (or to the host tissue) provides a uniquely sensitive
way to explore biocompatibility. An understanding of how to direct specific substratumcellular
responses is critical for the development of future biomaterials (e.g., for
prosthesis).
Attachment and spreading of a cell to and on a substratum are the first part of the
process that leads to the ultimate assimilation of the new cell or prosthesis with the host
tissue. Together with conventional microscopy, I have exploited a uniquely powerful
noninvasive optical technique (Optical Waveguide Lightmode Spectroscopy, OWLS) to
quantify cell attachment and spreading of stem cells to artificial biomaterials, and
determine how the cell environment (the substratum),the complex liquid medium
bathing the cell, and the presence of congeners, influence attachment and spreading.
My results highlight that quantitative characterisation of interfacial interactions,
including their kinetics leads to uniquely new insight into cell-protein-material
interactions. This knowledge will be doubtless be useful in the development of new
generations of biomaterials with improved properties designed for specific applications
Dual origin of avian lymphatics
No full textAbstractThe earliest signs of the lymphatic vascular system are the lymph sacs, which develop adjacent to specific embryonic veins. It has been suggested that sprouts from the lymph sacs form the complete lymphatic vascular system. We have studied the origin of the jugular lymph sacs (JLS), the dermal lymphatics and the lymph hearts of avian embryos. In day 6.5 embryos, the JLS is an endothelial-lined sinusoidal structure. The lymphatic endothelial cells (LECs) stain (in the quail) positive for QH1 antibody and soybean agglutinin. As early as day 4, the anlagen of the JLS can be recognized by their Prox1 expression. Prox1 is found in the jugular section of the cardinal veins, and in scattered cells located in the dermatomes along the cranio-caudal axis and in the splanchnopleura. In the quail, such cells are positive for Prox1 and QH1. In the jugular region, the veins co-express the angiopoietin receptor Tie2. Quail-chick-chimera studies show that the peripheral parts of the JLS form by integration of cells from the paraxial mesoderm. Intra-venous application of DiI-conjugated acetylated low-density lipoprotein into day 4 embryos suggests a venous origin of the deep parts of the JLS. Superficial lymphatics are directly derived from the dermatomes, as shown by dermatome grafting. The lymph hearts in the lumbo-sacral region develop from a plexus of Prox1-positive lymphatic capillaries. Both LECs and muscle cells of the lymph hearts are of somitic origin. In sum, avian lymphatics are of dual origin. The deep parts of the lymph sacs are derived from adjacent veins, the superficial parts of the JLS and the dermal lymphatics from local lymphangioblasts
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