Les extraits de sols saturés à l’eau et le suivi des nutriments dans l’érablière dépérissante

1994 ◽  
Vol 74 (2) ◽  
pp. 247-255
Author(s):  
F. Marquis ◽  
C. Camiré
Keyword(s):  
Chemical Properties ◽  
Field Capacity ◽  
Potential Toxicity ◽  
Conventional Analysis ◽  
Water Field ◽  
Chemical Properties Of Soils ◽  
Water Saturated ◽  
Saturated Extract

The soil solution provides the majority of essential nutrients needed for plant growth. Obtaining this solution in situ presents logistic problems and therefore most results are obtained from air-dried soils, even though chemical properties of soils can be substantially modified by drying. Water-saturated extracts obtained from dried soils were tested for their efficiency to detect the effects of in situ fertilization with P-TSP, K-K2SO4 and Ca-Ca(OH)2 on the Ahe horizon of a maple stand. Results obtained with water-saturated extracts on dried soils were compared with those obtained from conventional (exchangeable) extraction on dried soils and to those obtained from extraction with a soil:water ratio of 1:5 on dried soils. A similar experiment comparing water-saturated extracts with the soil:water ratio of 1:5 was carried out using soils fertilized in vitro. The effects of fertilization were clearly evident with saturated extracts when these could be observed by conventional analysis. Furthermore, the saturated extract indicated potential toxicity of Al in relation to pH. For the same samples, the saturated extracts were more sensitive than the extracts with a soil:solution ratio of 1:5, especially with regard to element ratios not easily expressed by conventional analysis. The originality of this method rests on a combination of efficient centrifugation with a double bottom container, the convenience in the utilization of air-dried soils and the use of near water field capacity as a representative water content. Key words: Saturated extracts, fertilization, toxicity, maple stand

Morphological and Chemical Characteristics of Soil Catenas on Pinedale and Bull Lake Moraine Slopes in the Salmon River Mountains, Idaho

1987 ◽  
Vol 28 (2) ◽  
pp. 210-225 ◽  
Author(s):  
Margaret E. Berry
Keyword(s):  
Soil Properties ◽  
Chemical Properties ◽  
Clay Content ◽  
Soil Development ◽  
Slope Position ◽  
Salmon River ◽  
Chemical Properties Of Soils ◽  
Film Development ◽  
Pedogenic Processes

AbstractMorphological and chemical properties of soils developed on moraines of granitic composition, and forested with lodgepole pine, in Bear Valley, Idaho, change significantly with age and slope position. Soil development on Pinedale and Bull Lake moraine slopes of similar curvature and steepness was assessed at the summits, shoulders, backslopes, and footslopes of both catenas, and at the toeslope of the Bull Lake catena. Many soil properties show trends in development with both age and slope position. These properties include clay content, clay film development, color, plagioclase weathering, and dithionite-citrate-extractable iron (Fed). The degree of development of all these properties is greater on the Bull Lake catena relative to that on the Pinedale catena. This trend reflects increased soil development with age. On both catenas, development of soil properties is commonly highest at the footslope or toeslope sites and minimum at the backslope site. Downslope changes are attributed to both colluviation and pedogenic processes, including sorting of sediments during downslope transport, greater accumulation of eolian materials transported to downslope sites by surface processes, and greater in situ weathering of mineral grains at the footslope and toeslope sites.

scholarly journals CYCLODEXTRIN DERIVATIVE ENHANCES THE OPHTHALMIC DELIVERY OF POORLY SOLUBLE AZITHROMYCIN

2020 ◽  
Author(s):  
Anil Thakur ◽  
Sourabh Jain ◽  
Anjali Pant ◽  
Akanksha Sharma ◽  
Rajiv Kumar ◽  
...  
Keyword(s):  
Drug Release ◽  
Inclusion Complex ◽  
Hydroxypropyl Methylcellulose ◽  
Chemical Properties ◽  
Antimicrobial Efficacy ◽  
Phase Solubility ◽  
Efficient Treatment ◽  
Carbopol 934P

AbstractAzithromycin (AZM), a macrolide antibiotic used for the treatment of Chlamydial conjunctivitis, is less effective for the treatment of this disease due to its poor bioavailability (38%). Various alternatives have been developed for improving the physico-chemical properties (i.e., solubility) of the AZM without much success. To overcome the problems associated with AZM, an inclusion complex employing a modified cyclodextrin i.e., sulfobutylether-β-cyclodextrin (SBE-β-CD) was prepared and characterized by phase solubility studies, pXRD and FTIR techniques. The results portrayed the formation of the inclusion complex of AZM with sulfobutylether β-cyclodextrin (SBE-β-CD) in 1:2 molar stoichiometric ratios. This inclusion complex was later incorporated into a polymer matrix to prepare an in situ gel. Various combinations of carbopol 934P and hydroxypropyl methylcellulose (HPMC K4M) polymers were used and evaluated by rheological and in vitro drug release studies. The optimized formulation (F4), containing carbopol 934P 0.2% (w/v) and HPMC K4M 0.2% (w/v), was evaluated for clarity, pH, gelling capacity, drug content, rheological properties, in vitro drug release pattern, ocular irritation test and antimicrobial efficacy. Finally, owing to the improved antimicrobial efficacy and increased residence time, AZM:SBE-β-CD in situ gel was found to be a promising formulation for the efficient treatment of bacterial ocular disease.

Correlated Studies of Cellular Interactions Using TEM, Freeze Etching, and SEM

1974 ◽  
Vol 32 ◽  
pp. 320-321
Author(s):  
J. P. Revel
Keyword(s):  
Developmental Stages ◽  
Three Dimensional ◽  
Cell Movement ◽  
Cellular Interactions ◽  
Serial Sections ◽  
Cell Sheets ◽  
Freeze Etching ◽  
Early Developmental

Movement of individual cells or of cell sheets and complex patterns of folding play a prominent role in the early developmental stages of the embryo. Our understanding of these processes is based on three- dimensional reconstructions laboriously prepared from serial sections, and from autoradiographic and other studies. Many concepts have also evolved from extrapolation of investigations of cell movement carried out in vitro. The scanning electron microscope now allows us to examine some of these events in situ. It is possible to prepare dissections of embryos and even of tissues of adult animals which reveal existing relationships between various structures more readily than used to be possible vithout an SEM.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

Cathodoluminescence of Catalyst Crystallites

1982 ◽  
Vol 40 ◽  
pp. 664-665
Author(s):  
E.D. Boyes ◽  
P.L. Gai ◽  
D.B. Darby ◽  
C. Warwick
Keyword(s):  
Defect Density ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Semiconductor Materials ◽  
Environmental Cell ◽  
High Resolution Structure ◽  
Commercially Important ◽  
Crystallographic Defects ◽  
Resolution Structure

The extended crystallographic defects introduced into some oxide catalysts under operating conditions may be a consequence and accommodation of the changes produced by the catalytic activity, rather than always being the origin of the reactivity. Operation without such defects has been established for the commercially important tellurium molybdate system. in addition it is clear that the point defect density and the electronic structure can both have a significant influence on the chemical properties and hence on the effectiveness (activity and selectivity) of the material as a catalyst. SEM/probe techniques more commonly applied to semiconductor materials, have been investigated to supplement the information obtained from in-situ environmental cell HVEM, ultra-high resolution structure imaging and more conventional AEM and EPMA chemical microanalysis.

In Situ Localization of PPAR Gamma and Uncoupling Protein in Mouse Embryo Sections Using Digoxigenin-Labeled Riboprobes

1996 ◽  
Vol 54 ◽  
pp. 32-33
Author(s):  
C. Jennermann ◽  
S. A. Kliewer ◽  
D. C. Morris
Keyword(s):  
Alkaline Phosphatase ◽  
Room Temperature ◽  
Uncoupling Protein ◽  
Ppar Gamma ◽  
Nuclear Hormone Receptor ◽  
Full Length ◽  
Northern Analysis ◽  
Peroxisome Proliferator

Peroxisome proliferator-activated receptor gamma (PPARg) is a member of the nuclear hormone receptor superfamily and has been shown in vitro to regulate genes involved in lipid metabolism and adipocyte differentiation. By Northern analysis, we and other researchers have shown that expression of this receptor predominates in adipose tissue in adult mice, and appears first in whole-embryo mRNA at 13.5 days postconception. In situ hybridization was used to find out in which developing tissues PPARg is specifically expressed.Digoxigenin-labeled riboprobes were generated using the Genius™ 4 RNA Labeling Kit from Boehringer Mannheim. Full length PPAR gamma, obtained by PCR from mouse liver cDNA, was inserted into pBluescript SK and used as template for the transcription reaction. Probes of average size 200 base pairs were made by partial alkaline hydrolysis of the full length transcripts. The in situ hybridization assays were performed as described previously with some modifications. Frozen sections (10 μm thick) of day 18 mouse embryos were cut, fixed with 4% paraformaldehyde and acetylated with 0.25% acetic anhydride in 1.0M triethanolamine buffer. The sections were incubated for 2 hours at room temperature in pre-hybridization buffer, and were then hybridized with a probe concentration of 200μg per ml at 70° C, overnight in a humidified chamber. Following stringent washes in SSC buffers, the immunological detection steps were performed at room temperature. The alkaline phosphatase labeled, anti-digoxigenin antibody and detection buffers were purchased from Boehringer Mannheim. The sections were treated with a blocking buffer for one hour and incubated with antibody solution at a 1:5000 dilution for 2 hours, both at room temperature. Colored precipitate was formed by exposure to the alkaline phosphatase substrate nitrobluetetrazoliumchloride/ bromo-chloroindlylphosphate.

CONSERVATION OF RARE SPECIES PLANTS AND LICHENS IN SITU WITH PLANNED ANTHROPOGENIC ACTIVITIES: BASIC APPROACHES AND IMPLEMENTATION PRINCIPLES

2018 ◽  
Vol 12 (7-8) ◽  
pp. 38-45
Author(s):  
A. N. EFREMOV ◽  
N. V. PLIKINA ◽  
T. ABELI
Keyword(s):  
Rare Species ◽  
Technology Implementation ◽  
Technology Development ◽  
Anthropogenic Activities ◽  
Natural Habitat ◽  
Local Population ◽  
Main Stage ◽  
Social Risks

Rare species are most vulnerable to man-made impacts, due to their biological characteristics or natural resource management. As a rule, the economic impact is associated with the destruction and damage of individual organisms, the destruction or alienation of habitats. Unfortunately, the conservation of habitat integrity is an important protection strategy, which is not always achievable in the implementation of industrial and infrastructural projects. The aim of the publication is to summarize the experience in the field of protection of rare species in the natural habitat (in situ), to evaluate and analyze the possibility of using existing methods in design and survey activities. In this regard, the main methodological approaches to the protection of rare species in the natural habitat (in situ) during the proposed economic activity were reflected. The algorithm suggested by the authors for implementing the in situ project should include a preparatory stage (initial data collection, preliminary risk assessments, technology development, obtaining permitting documentation), the main stage, the content of which is determined by the selected technology and a long monitoring stage, which makes it possible to assess the effectiveness of the taken measures. Among the main risks of in situ technology implementation, the following can be noted: the limited resources of the population that do not allow for the implementation of the procedure without prior reproduction of individuals in situ (in vitro); limited knowledge of the biology of the species; the possibility of invasion; the possibility of crossing for closely related species that сo-exist in the same habitat; social risks and consequences, target species or population may be important for the local population; financial risks during the recovery of the population. The available experience makes it possible to consider the approach to the conservation of rare species in situ as the best available technology that contributes to reducing negative environmental risks.

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