Increasing Pressure (increasing + pressure)

Distribution by Scientific Domains
Distribution within Chemistry


Selected Abstracts


Micronization of the officinal component baicalin by SEDS-PA process

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2007
Wen Zhi He
Abstract Application of micronizing technologies in processing Chinese herbal medicines is very important to improve the forms of prepared Chinese herbal medicines and promote their therapeutic efficacy. Baicalin, a major active component of the typical Chinese herb medicine Scullateria baicallensis Georgi, was micronized using the Solution Enhanced Dispersion by Supercritical fluids though Prefilming Atomization (SEDS-PA) process with the aim of evaluating the efficiency of applying supercritical fluid precipitation technologies in Chinese herb medicine. This study has shown that acicula or rod-like baicalin crystals with Particle Size (PS) of about 20×100 ,m were successfully micronized by the SEDS-PA process to long rod-like, twisted fiber-like or fibrous net-like microparticles with PS of 0.1-2.2 ,m in width within the range of experiments performed. It was found that a substantial reduction of baicalin microparticles' sizes could lead to a marked increase of adhesions among them and subsequent microparticles agglomeration. With the increase of supercritical CO2 flow rate and the decrease of solution concentration and solution flow rate, smaller and much more agglomerated microparticles were obtained. Increasing pressure led to formation of smaller microparticles. A larger tendency of particles agglomeration was produced at a higher temperature. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Auditor Independence: A Comparative Descriptive Study of the UK, France and Italy

INTERNATIONAL JOURNAL OF AUDITING, Issue 2 2002
Joanna E. Stevenson
The independence of the external auditor has long been a subject of great debate, particularly by UK and US interested parties. With the growth and globalisation of the large multi-disciplinary firms, it has again been pushed to the fore: new ethical guidance issued by international bodies such as La Fédération des Experts- Comptables Européens (FEE) and The International Federation of Accountants (IFAC) and the activities of the Securities and Exchange Commission (SEC) and Independence Standards Board in the US have encouraged a wider consideration of the issue. In Europe, the European Commission has issued a Consultative Paper containing fundamental principles for adoption into Member States' own regulation on statutory auditor independence. Increasing pressure for the removal of obstacles to a single European audit market have resulted in safeguards of auditor independence in some countries being described as undesirable barriers. This paper considers the issue of statutory auditor independence across three EU Member States: the UK, France and Italy, by comparing the ethical guides and the legal and professional regulations in place, highlighting and discussing areas of divergence, and contrasting them with the EC's Consultative Paper. It takes into account factors such as culture and the historical development of auditing in order to explore the differences found. The paper demonstrates that positions taken in France and Italy on the issue of auditor independence differ markedly from that taken by the UK profession. Of the three countries reviewed, the UK viewpoint has most obviously influenced the drafting of the EC Paper. The implications of these variances for EU harmonisation are discussed, and the paper concludes that there is a clear need for empirical study of this important issue in Europe to better understand the reasons for differing perceptions and attitudes, and the repercussions of these differences on the process of European audit harmonisation. [source]


Corporate Governance in Germany: the move to shareholder value

CORPORATE GOVERNANCE, Issue 3 2001
Florian Schilling
The paper offers an inside view of the German corporate governance model, based on interviews with over 100 members of supervisory- (Aufsichtsrat) and executive-boards (Vorstand) of major German corporations. The traditional supervisory board with its large size of 20 members, one half elected by the employees, reflects the strong consensus orientation of the German corporate world. This system worked well in times of long innovation cycles and largely separate, national capital markets. It is coming under increasing pressure to adapt to the demands of a fast changing globalised capital market.Keywords: Corporate governance in Germany, supervisory board, codetermination, board composition, professionalisation of boards [source]


Industry responses to EU WEEE and ROHS Directives: perspectives from China

CORPORATE SOCIAL RESPONSIBILITY AND ENVIRONMENTAL MANAGEMENT, Issue 5 2006
Jieqiong Yu
Abstract The electrical and electronics (EE) industry has come under increasing pressure to adopt extended producer responsibility (EPR) policies through the introduction of the European Union's Directives on Waste Electrical and Electronic Equipment (WEEE) and the Restriction of Use of Certain Hazardous Substances (ROHS). Based on the findings of 50 questionnaires and in-depth interviews with China's EE manufacturers, this paper investigates the perception of and readiness of companies for implementation of WEEE and ROHS in China. It identifies key difficulties encountered by manufacturers in fulfilling the requirements and evaluates the effectiveness of these two directives in promoting environmental reform. The findings indicate that the extent of companies' responses largely depends on their market structure and client requirements. Supply chain management, raw material testing and cost implications appear to be key challenges in addressing issues surrounding the directives. There is little evidence to suggest that these directives have effectively driven China's EE manufacturers towards systematic eco-design. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment. [source]


The Audit Commission review of diabetes services in England and Wales, 1998,2001

DIABETIC MEDICINE, Issue 2002
B. Fitzsimons
Abstract Aims of the Audit Commission The Audit Commission has a statutory duty to promote the best use of public money. It does this through value for money studies, such as that reported in Testing Times[1]. This work has been followed with a review of innovative practice in commissioning. These initiatives aim to support the implementation of the diabetes national service framework. The Audit Commission also appoints external auditors to NHS organizations who assess probity and value for money in the NHS; the latter by applying national studies locally and by carrying out local studies. Methods Research for Testing Times consisted of structured visits to nine acute trusts, a telephone survey of 26 health authorities and a postal survey of 1400 people with diabetes and 250 general practitioners. Local audits used a subset of the original research tools. Case studies were identified through a cascade approach to contacts established during Testing Times and through self-nomination. Results Rising numbers of people with diabetes are placing increasing pressure on hospital services. Some health authorities and primary care organizations have reviewed patterns of service provision in the light of the increasing demands. These reviews show wide variations in patterns of routine care. In addition, there is a widespread lack of data on the delivery of structured care to people with diabetes. People with diabetes report delays in gaining access to services, and insufficient time with staff. There are insufficient arrangements in place for providing information and learning opportunities to support self-management. Conclusion As the number of people with diabetes continues to rise, the potential for providing more care in a primary care setting needs to be explored. This will enable specialist services to focus more effectively on those with the most complex needs. [source]


Modelling land use changes and their impact on soil erosion and sediment supply to rivers

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2002
Anton J. J. Van Rompaey
Abstract The potential for surface runoff and soil erosion is strongly affected by land use and cultivation. Therefore the modelling of land use changes is important with respect to the prediction of soil degradation and its on-site and off-site consequences. Land use changes during the past 250 years in the Dijle catchment (central Belgium) were analysed by comparing four historical topographic maps (1774, 1840, 1930 and 1990). A combination of land use transformation maps and biophysical land properties shows that certain decision rules are used for the conversion of forest into arable land or vice versa. During periods of increasing pressure on the land, forests were cleared mainly on areas with low slope gradients and favourable soil conditions, while in times of decreasing pressure land units with steep and unfavourable soil conditions were taken out of production. Possible future land use patterns were generated using stochastic simulations based on land use transformation probabilities. The outcome of these simulations was used to assess the soil erosion risk under different scenarios. The results indicate that even a relatively limited land use change, from forest to arable land or vice versa, has a significant effect on regional soil erosion rates and sediment supply to rivers. Copyright © 2002 John Wiley & Sons, Ltd. [source]


Criteria for the assessment of processes for sustainable river basin management and their congruence with the EU Water Framework Directive

ENVIRONMENTAL POLICY AND GOVERNANCE, Issue 4 2008
Beatrice Hedelin
Abstract In order to manage the increasing pressure on the world's water resources, new planning methodologies/processes for sustainable river basin management are currently being developed. For such processes to work well, however, the legal context must allow, or support, such processes. In this study, a set of criteria relating to methodologies/processes for sustainable water management is used to assess the EU Water Framework Directive (WFD). The study suggests that the WFD erects few formal barriers to good planning practices. However, planning processes will need to be adapted to compensate for the weak legal support in a number of important areas, namely the use of knowledge from beyond the natural sciences, the use of methodologies for the explicit handling of values and the use of procedures for democratic participation. In so doing the issues identified here provide a basis for systematic thinking about how to design the necessary planning processes. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment. [source]


Pressure Effect Investigations on the Spin Crossover Systems{Fe[H2B(pz)2]2(bipy)} and {Fe[H2B(pz)2]2(phen)}

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2006
Ana Galet
Abstract Pressure effect studies on the spin crossover behaviour of the mononuclear compounds {Fe[H2B(pz)2]2(bipy)}(1) and {Fe[H2B(pz)2]2(phen)}(2) have been performed in the range of 105 Pa,1.02 GPa at variable temperatures (100,310 K). Continuous spin transitions and displacement of its characteristic temperature has been observed for 1 with increasing pressure. Meanwhile the response of 2 under applied pressures is quite unexpected, and can only be understood in terms of a crystallographic phase transition or change in the bulk modulus of the compound. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]


Referendums and the Political Constitutionalisation of the EU

EUROPEAN LAW JOURNAL, Issue 4 2008
Min Shu
One is the revision of national constitutions to accommodate the integration project at the national level. The other is the construction of transnational rules to regulate novel inter-state relationships at the European level. EU referendums are contextualised in such a duel constitutionalisation process. At the domestic level, EU referendums handle the debates on national constitutional revision. At the transnational level, these popular votes ratify supranational constitutional documents. The article comparatively analyses three types of EU referendums,membership, policy and treaty referendums,according to this analytical framework, exploring the campaign mobilisation of voters, national governments, and transnational institutions, and examining the legal and political interaction between referendums and European integration. A key finding is that, as the dual constitutionalisation process deepens and widens, entrenched domestic players and restrained transnational actors are under increasing pressure to ,voice' themselves in EU referendums. [source]


Response of native and denatured hen lysozyme to high pressure studied by 15N/1H NMR spectroscopy

FEBS JOURNAL, Issue 6 2001
Yuji O. Kamatari
High-pressure 15N/1H NMR techniques were used to characterize the conformational fluctuations of hen lysozyme, in its native state and when denatured in 8 m urea, over the pressure range 30,2000 bar. Most 1H and 15N signals of native lysozyme show reversible shifts to low field with increasing pressure, the average pressure shifts being 0.069 ± 0.101 p.p.m. (1H) and 0.51 ± 0.36 p.p.m. (15N). The shifts indicate that the hydrogen bonds formed to carbonyl groups or water molecules by the backbone amides are, on average, shortened by ,,0.02 Å as a result of pressure. In native lysozyme, six residues in the , domain or at the ,/, domain interface have anomalously large nonlinear 15N and 1H chemical-shift changes. All these residues lie close to water-containing cavities, suggesting that there are conformational changes involving these cavities, or the water molecules within them, at high pressure. The pressure-induced 1H and 15N shifts for lysozyme denatured in 8 m urea are much more uniform than those for native lysozyme, with average backbone amide shifts of 0.081 ± 0.029 p.p.m. (1H) and 0.57 ± 0.14 p.p.m. (15N). The results show that overall there are no significant variations in the local conformational properties of denatured lysozyme with pressure, although larger shifts in the vicinity of a persistent hydrophobic cluster indicate that interactions in this part of the sequence may rearrange. NMR diffusion measurements demonstrate that the effective hydrodynamic radius of denatured lysozyme, and hence the global properties of the denatured ensemble, do not change detectably at high pressure. [source]


Effects of pressure on the activity and spectroscopic properties of carboxyl proteinases

FEBS JOURNAL, Issue 3 2001
Apparent correlation of pepstatin-insensitivity, pressure response
The pressure dependence of the activity and spectroscopic properties of four carboxyl proteinases were investigated. Two were pepstatin-sensitive carboxyl proteinases (porcine pepsin and proteinase A from baker's yeast) and two were pepstatin-insensitive carboxyl proteinases (from Pseudomonas sp. 101 (pseudomonapepsin; PCP) and Xanthomonas sp. T-22 (xanthomonapepsin; XCP)). The specificity constant [kcat/Km(app)] of PCP and XCP for a synthetic peptide substrate showed only a slight decrease with increasing pressure, whereas pepsin and proteinase A showed substantial disactivation at higher pressures. The calculated apparent activation volume (,Vkcat/Km) was about 1, 3, 13, and 14 mL·mol,1 for PCP, XCP, pepsin, and proteinase A, respectively. The hydrolysis of acid-denatured myoglobin by the four carboxyl proteinases was only slightly affected by high pressure (except for proteinase A at 400 MPa), in contrast to the results for the peptide hydrolysis. In fact, PCP, XCP, and proteinase A actually showed slightly higher degradations of acid-denatured myoglobin at higher pressures. The residual activities of these enzymes after the incubation at high pressures implied a pressure-induced stabilization towards autolysis. The changes in the fourth derivative near-UV absorbance spectrum of the four enzymes in aqueous solution were measured at various pressures from 0.1 to 400 MPa. Upon an increase in pressure, the peaks from PCP and XCP red-shifted slightly, whereas pepsin and proteinase A blue-shifted substantially, thus indicating a more polar environment. The intrinsic fluorescence also decreased upon increasing pressure. However, the change for XCP was rather small, but the change for the other three was very large. The changes in the peak wavelength for pepsin and proteinase A were characteristic, and also indicated a more polar environment under high pressure. An analysis by the center of spectra mass (CSM) gave the ,G and ,V of transition as 9.8 kJ·mol,1 and ,24 mL·mol,1 (pepsin) and 11.7 kJ·mol,1 and ,43 mL·mol,1 (proteinase A), respectively, by assuming a simple two-state transition. The circular dichroism (CD) showed relatively small changes after 1-h incubations at 400 MPa, indicating that the secondary structures were largely maintained. [source]


A constitutive model for bonded geomaterials subject to mechanical and/or chemical degradation

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 9 2003
R. Nova
Abstract The mechanical behaviour of bonded geomaterials is described by means of an elastoplastic strain-hardening model. The internal variables, taking into account the ,history' of the material, depend on the plastic strains experienced and on a conveniently defined scalar measure of damage induced by weathering and/or chemical degradation. For the sake of simplicity, it is assumed that only internal variables are affected by mechanical and chemical history of the material. Despite this simplifying assumption, it can be shown that many interesting phenomena exhibited by weathered bonded geomaterials can be successfully described. For instance, (i) the transition from brittle to ductile behaviour with increasing pressure of a calcarenite with collapsing internal structure, (ii) the complex behaviour of chalk and other calcareous materials in oedometric tests, (iii) the chemically induced variation of the stress and strain state of such kind of materials, are all phenomena that can be qualitatively reproduced. Several comparisons with experimental data show that the model can capture the observed behaviour also quantitatively. Copyright © 2003 John Wiley & Sons, Ltd. [source]


Rates of Acute Care Admissions for Frail Older People Living with Met Versus Unmet Activity of Daily Living Needs

JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 2 2006
Laura P. Sands PhD
OBJECTIVES: To determine whether older people who do not have help for their activity of daily living (ADL) disabilities are at higher risk for acute care admissions and whether entry into a program that provides for these needs decreases this risk. DESIGN: A longitudinal cohort study. SETTING: Thirteen nationwide sites for the Program of All-inclusive Care for the Elderly (PACE). PACE provides comprehensive medical and long-term care to community-living older adults. PARTICIPANTS: Two thousand nine hundred forty-three PACE enrollees with one or more ADL dependencies. MEASUREMENTS: Unmet needs were defined as the absence of paid or unpaid assistance for ADL disabilities before PACE enrollment. Hospital admissions in the 6 months before PACE enrollment and acute admissions in the first 6 weeks and the 7th through 12th weeks after enrollment were determined. RESULTS: Those who lived with unmet ADL needs before enrollment were more likely to have a hospital admission before PACE enrollment (odds ratio (OR)=1.28, 95% confidence interval (CI)=1.01,1.63) and an acute admission in the first 6 weeks after enrollment (OR=1.45, 95% CI=1.00,2.09) but not after 6 weeks of receiving PACE services (OR=0.86, 95% CI=0.53,1.40). CONCLUSION: Frail older people who live without needed help for their ADL disabilities have higher rates of admissions while they are living with unmet ADL needs but not after their needs are met. With state governments under increasing pressure to develop fiscally feasible solutions for caring for disabled older people, it is important that they be aware of the potential health consequences of older adults living without needed ADL assistance. [source]


The continuous cooling transformation (CCT) as a flexible tool to investigate polymer crystallization under processing conditions

ADVANCES IN POLYMER TECHNOLOGY, Issue 2 2009
V. Brucato
Abstract An experimental route for investigating polymer crystallization over a wide range of cooling rates (from 0.01 to 1000°C/s) and pressures (from 0.1 to 40 MPa) is illustrated, using a method that recalls the approach adopted in metallurgy for studying structure development in metals. Two types of experimental setup were used, namely an apparatus for fast cooling of thin films (100,200 ,m thick) at various cooling rates under atmospheric pressure and a device (based on a on-purpose modified injection molding machine) for quenching massive samples (about 1,2 cm3) under hydrostatic pressure fields. In both cases, ex situ characterization experiments were carried out to probe the resulting structure, using techniques such as density measurements and wide-angle x-ray diffraction (WAXD) patterns. The cooling mechanism and temperature distribution across the sample thickness were analyzed. Results show that the final structure is determined only by the imposed thermal history and pressure. Experimental results for isotactic polypropylene (iPP), poly(ethylene terephthalate) (PET), polyamide 6 (PA6), and syndiotactic polystyrene (sPS) are reported, showing the reliability of this experimental approach to assess not only quantitative information but also a qualitative description of the crystallization behavior of different classes of semicrystalline polymers. The present study gives an opportunity to evaluate how the combined effect of the cooling rate and pressure influences the crystallization kinetics for various classes of polymer of commercial interest. An increase in the cooling rate translates into a decrease in crystallinity and density, which both experience a sudden drop around the specific "crystallizability" (or "critical cooling rate") of the material examined. The exception is sPS where competition among the various crystalline modifications determines a minimum in the plot of density vs. cooling rate. As for the effect of pressure, iPP exhibits a "negative dependence" of crystallization kinetics upon pressure, with a decrease of density and degree of crystallinity with increasing pressure, owing to kinetic constraints. PA6 and PET, on the other hand, due to thermodynamic factors resulting in an increase in Tm with pressure, exhibits a "positive dependence" of crystallization kinetics upon pressure. Finally, recent original results concerning sPS have shown that the minimum in the density vs. cooling rate curve shifts toward larger cooling rates upon increasing pressure. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:86,119, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20151 [source]


Parametric Rietveld refinement for the evaluation of powder diffraction patterns collected as a function of pressure

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2010
Ivan Halasz
Under the assumption that the structural parameters of a crystalline phase change `smoothly' with increasing pressure, the evolution of the parameters can be parameterized as a function of pressure using continuous monotonic functions. Four different approaches to determine the structural evolution of As2O5 with increasing pressure from a set of powder diffraction patterns collected over the pressure range from 2.5 to 19.5,GPa have been investigated. Approach (A) was the common sequential refinement of atomic coordinates with restraints on the geometry and was compared with three parameterization approaches. Approach (B) used direct parameterization by low-order polynomials of each crystallographically distinct atomic coordinate, (C) described the atoms of the asymmetric unit as a rigid body and allowed the internal degrees of freedom of the rigid body to vary with the change in pressure using rigid unit modes, and (D) described the crystal structure as a distortion of the higher-symmetry structure of As2O5 (which is here also a high-temperature phase) by using symmetry-adapted distortion modes. Approach (D) offers the possibility to directly introduce an order parameter into Rietveld refinement through an empirical power law derived from Landau theory and thus to obtain the value of the critical exponent. In contrast, the rigid-body approach did not fit the data as well. All parameterizations greatly reduce the number of required parameters. [source]


Synthesis of charged ultrafiltration poly(styrene- co -divinyl benzene) composite membrane

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008
Sonny Sachdeva
Abstract A ceramic supported crosslinked polystyrene composite membrane has been prepared from its monomers using a dual initiator system. The nonionic hydrophobic membrane so prepared has been chemically modified by a low temperature (50°C), single step reaction with chloroacetic acid. The carboxylated membrane has acid functional groups on its surface making it negatively charged and highly hydrophilic in nature. The membranes (unmodified and carboxylated) have been used for the separation of hazardous chromium (VI) salt solution where observed and intrinsic rejection has been studied as a function of pressure and concentration of the feed solution. The intrinsic rejection has been determined by calculating the concentration at the membrane surface (Cm) using Speigler-Kedam model and osmotic pressure model. The observed rejection for the chemically modified membrane decreases with increasing pressure but the intrinsic rejection is found to be more than 80% for all concentrations in the range of study. The experimental results have been fitted using Space-Charge model to obtain the membrane wall potential and the membrane surface concentration which are difficult to measure directly. The transport through the membrane capillaries has been described by the two dimensional model using Nernst-Planck equation for ion transport, Navier-Stokes equation and Poisson-Boltzmann equation for the radial distribution of potential. We have then presented a semianalytical series solution to the highly nonlinear Poisson-Boltzmann equation to reduce the computational time required to solve the set of coupled differential equations. The effective wall potential of the carboxylated membrane was found to be ,28.07 mV. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]


Exclusion of livestock grazing and wood collection in dryland savannah: an effect on long-term vegetation succession

AFRICAN JOURNAL OF ECOLOGY, Issue 2 2010
Pavla Hejcmanová
Abstract Sahelian savannah faces increasing pressure from human activities, leading to its degradation. The aim of this study was to investigate the possibility of restoration of dryland savannah vegetation by the elimination of disturbance factors on the ecosystem. Is degraded dryland savannah vegetation able to be restored by means of natural succession? What is the timescale for its recovery? The study took place in the Bandia Reserve, 65 km south-east of Dakar (Senegal), a unique site with two successional stages due to the elimination of uncontrolled exploitation. The vegetation structure of 15 years (15YRS) and 5 years (5YRS) after fencing was compared with vegetation exposed to continuous livestock grazing and wood collection outside the fenced area. Calculated by redundancy analysis, a significant effect of selected areas on the cover of all species was revealed and successional stage explained more than 45% of data variability. Perennial forbs, annual forbs and perennial grasses achieved the highest cover in 5YRS, woody species in 15YRS and annual grasses in the area outside of the fenced reserve. The dominant woody species Acacia seyal, A. ataxacantha, A. nilotica subsp. adstringens and Balanites aegyptiaca reconstituted the dense formation of Acacia bushland by means of natural succession in the 15YRS area. Résumé La savane sahélienne subit une pression croissante des activités humaines, qui entraînent sa dégradation. Le but de cette étude était d'étudier la possibilité de restaurer la végétation de la savane sèche en éliminant les facteurs de perturbation de l'écosystème. La végétation de savane sèche est-elle capable de se rétablir par voie de succession naturelle ? Quelle est l'échelle de temps de cette restauration ? Cette étude a eu lieu dans la Réserve de Bandia, située à 65 km au sud-est de Dakar (Sénégal), un site unique qui enclot deux stades de succession en raison de la fin de son exploitation incontrôlée. La structure de la végétation qui s'est développée quinze ans (15 A) et cinq ans (5 A) après la pose d'une clôture a été comparée à la végétation exposée au pâturage continu du bétail et à la collecte de bois, en dehors de la clôture. Une analyse de redondance a révélé un effet significatif des zones choisies sur la couverture de toutes les espèces, et le stade de succession a permis d'expliquer plus de 45% de la variabilité des données. Les dicotylédones pérennes et annuelles et les monocotylédones pérennes atteignaient la plus grande couverture en 5 A, les espèces ligneuses en 15 A, et les monocotylédones annuelles dans la zone située en dehors de l'aire clôturée. Les espèces ligneuses dominantes, Acacia seyal, A. ataxacantha, A. nilotica subsp. adstringens et Balanites aegyptiaca ont reconstitué la formation dense d'une brousse àAcacia par la succession naturelle dans la zone 15 A. [source]


Land use/cover changes and their implications on rural livelihoods in the degraded environments of central Tanzania

AFRICAN JOURNAL OF ECOLOGY, Issue 2009
Richard Y. M. KangalaweArticle first published online: 3 FEB 200
Abstract This paper examines the changes in land use/cover types in the degraded environment of central Tanzania over the last 45 years, and how such changes have influenced agricultural and livelihoods sustainability, especially in the Irangi Hills. Changes of land use/cover were measured through aerial photographs interpretations, while local perceptions and description of change were addressed through household interviews and field observations. The results of this study show that there have been variations over the years in terms of both the areas and spatial distribution of cultivated fields. The total land cultivated increased from 31% in the late 1970s to 35% in early 1990s, mainly because of agricultural expansion to sandy watercourses and former grazing areas. Water courses shrank by 55% between late 1970s and early 1990s providing new areas for cultivation. Over the last 45 years, the open and wooded grasslands, and tree-cover types covered about 40% of the total land area, ranging from 29% in 1960 to 43,45% between late 1970s and early 1990s. Spatial and temporal distribution of the cultivated fields and other vegetation cover types were influenced by differences in the scale of land degradation, and the soil-conservation initiatives that have been implemented. With increasing pressure on the land, however, sustaining livelihoods through agricultural production in the area remains a critical challenge. [source]


Do Consumers Expect Companies to be Socially Responsible?

JOURNAL OF CONSUMER AFFAIRS, Issue 1 2001
The Impact of Corporate Social Responsibility on Buying Behavior
Companies are facing increasing pressure to both maintain profitability and behave in socially responsible ways, yet researchers have provided little information on how corporate social responsibility impacts profitability. This paper reports the findings from in-depth interviews of consumers to determine their views concerning the social responsibilities of companies. A typology of consumers whose purchasing behavior ranges from unresponsive to highly responsive to corporate social responsibility was developed from the analysis. [source]


Combined Pressure,temperature Inactivation of Alkaline Phosphatase in Bovine Milk: A Kinetic Study

JOURNAL OF FOOD SCIENCE, Issue 1 2000
L. Ludikhuyze
ABSTRACT: A detailed kinetic study on pressure-temperature inactivation of alkaline phosphatase has been performed in the pressure range 0.1 to 725 MPa at temperatures between 25 and 63 °C. Inactivation could be accurately described by a first order kinetic model, allowing D-values to be calculated. According to the thermal death time terminology, zr - and zp -values were calculated, expressing temperature and pressure dependence respectively. However, at high temperature, pressure dependence could not be calculated unambiguously. D-values firstly increased with increasing pressure up to 300 MPa and then decreased with further pressure increase, showing thermal inactivation to be counteracted by low pressure. Finally, a global model describing the D-value as a function of pressure and temperature has been formulated. [source]


Prograde pressure,temperature paths in the pelitic schists of the Sambagawa metamorphic belt, SW Japan

JOURNAL OF METAMORPHIC GEOLOGY, Issue 6 2002
M. Inui
Abstract Prograde P,T paths recorded by the chemistry of minerals of subduction-related metamorphic rocks allow inference of tectonic processes at convergent margins. This paper elucidates the changing P,T conditions during garnet growth in pelitic schists of the Sambagawa metamorphic belt, which is a subduction related metamorphic belt in the south-western part of Japan. Three types of chemical zoning patterns were observed in garnet: Ca-rich normal zoning, Ca-poor normal zoning and intrasectoral zoning. Petrological studies indicate that normally-zoned garnet grains grew keeping surface chemical equilibrium with the matrix, in the stable mineral assemblage of garnet + muscovite + chlorite + plagioclase + paragonite + epidote + quartz ± biotite. Pressure and temperature histories were inversely calculated from the normally-zoned garnet in this assemblage, applying the differential thermodynamic method (Gibbs' method) with the latest available thermodynamic data set for minerals. The deduced P,T paths indicate slight increase of temperature with increasing pressure throughout garnet growth, having an average dP/dT of 0.4,0.5 GPa/100 °C. Garnet started growing at around 470 °C and 0.6 GPa to achieve the thermal and baric peak condition near the rim (520 °C, 0.9 GPa). The high-temperature condition at relatively low pressure (for subduction related metamorphism) suggests that heating occurred before or simultaneously with subduction. [source]


Understanding the essential elements of work-based learning and its relevance to everyday clinical practice

JOURNAL OF NURSING MANAGEMENT, Issue 6 2010
BSc (Hons) Nurse Practitioner, CAROLINE WILLIAMS RN, Dip N, MSc (Nursing), PGCE (FE), PGCert (Facilitation & life-long learning)
williams c. (2010) Journal of Nursing Management 18, 624,632 Understanding the essential elements of work-based learning and its relevance to everyday clinical practice Aim, To critically review the work-based learning literature and explore the implications of the findings for the development of work-based learning programmes. Background, With NHS budgets under increasing pressure, and challenges to the impact of classroom-based learning on patient outcomes, work-based learning is likely to come under increased scrutiny as a potential solution. Evidence from higher education institutions suggests that work-based learning can improve practice, but in many cases it is perceived as little more than on-the-job training to perform tasks. Evaluation, The CINAHL database was searched using the keywords work-based learning, work-place learning and practice-based learning. Those articles that had a focus on post-registration nursing were selected and critically reviewed. Key issues, Using the review of the literature, three key issues were explored. Work-based learning has the potential to change practice. Learning how to learn and critical reflection are key features. For effective work-based learning nurses need to take control of their own learning, receive support to critically reflect on their practice and be empowered to make changes to that practice. Conclusions, A critical review of the literature has identified essential considerations for the implementation of work-based learning. A change in culture from classroom to work-based learning requires careful planning and consideration of learning cultures. Implications for nursing management, To enable effective work-based learning, nurse managers need to develop a learning culture in their workplace. They should ensure that skilled facilitation is provided to support staff with critical reflection and effecting changes in practice. Contribution to New Knowledge, This paper has identified three key issues that need to be considered in the development of work-based learning programmes. [source]


Axial liquid mixing in high-pressure bubble columns

AICHE JOURNAL, Issue 8 2003
G. Q. Yang
Axial dispersion coefficients of the liquid phase in bubble columns at high pressure are investigated using the thermal dispersion technique. Water and hydrocarbon liquids are used as the liquid phase. The system pressure varies up to 10.3 MPa and the superficial gas velocity varies up to 0.4 cm/s, which covers both the homogeneous bubbling and churn-turbulent flow regimes. Experimental results show that flow regime, system pressure, liquid properties, liquid-phase motion, and column size are the main factors affecting liquid mixing. The axial dispersion coefficient of the liquid phase increases with an increase in gas velocity and decreases with increasing pressure. The effects of gas velocity and pressure on liquid mixing can be explained based on the combined mechanism of global liquid internal circulation and local turbulent fluctuations. The axial liquid dispersion coefficient also increases with increasing liquid velocity due to enhanced liquid-phase turbulence. The scale-up effect on liquid mixing reduces as the pressure increases. [source]


Effect of pressure on the luminescence of a series of methoxy phenylacetylene dendrimers neat and in dilute solution in solid poly(tert -butyl methacrylate)

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2001
A. Zhu
Abstract The effect of pressure up to 60 kbar was measured on the luminescence peak location and efficiency for a series of methoxy phenylacetylene dendrimers (MeO). Dendrimers MeO-3, MeO-7, MeO-15, MeO-31, MeO-63, and MeO-127 were studied as neat polymers. MeO-3, MeO-15, MeO-63, and MeO-127 were also investigated in dilute solutions in poly(tert -butyl methacrylate). According to measurements of the dilute solutions, there is a charge-transfer (CT) state that, for the smaller dendrimers, lies well above the ,* state; for the larger dendrimers, it is the emitting state at 1 atm. With increasing pressure, the intramolecular CT state is rapidly stabilized, so that at high pressure the emission is from this state for all dendrimers. For the neat polymers, there is an initial redshift that reverses direction at a pressure that is higher for smaller dendrimers. This reversal is attributed to intermolecular CT. There may be changes in the molecular geometry and/or relative orientation of adjacent dendrimers that tend to stabilize the intermolecular CT in the solid state. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2859,2865, 2001 [source]


Pressure effects on inter- and intramolecular vibrations in hydrogen-bonded L -ascorbic acid crystal

JOURNAL OF RAMAN SPECTROSCOPY, Issue 1 2008
Hiroko Shimada
Abstract Pressure effects on the Raman spectra due to the inter- and intramolecular vibrations of the L -ascorbic acid crystal were studied. The intensity of the Raman bands due to the intermolecular vibrations varies in three different ways by application of pressure. The bands of the first group become stronger, those of the second one become weaker and the third group shows no prominent change in their intensity with increasing pressure. The bands due to the intermolecular vibrations show a blue shift, while the bands due to the intramolecular vibrations shift to the blue or red depending on the vibrational modes by application of pressure. The bands assigned to the OH stretching vibrations shift to the red, the bands assigned to the CO and CC stretching vibrations shift a little to the red and the bands assigned to the other vibrations shift to the blue under high pressure. The following conclusions were derived. (1) The hydrogen bonds forming helixes become stronger and the isolated hydrogen bond becomes weaker with increasing pressure. (2) The bands of the first group owing to the intermolecular vibrations are ascribed to the vibrations related to the helix hydrogen bonds and the second group bands to the isolated hydrogen bond. (3) The CO stretching vibration couples with the CC stretching vibration. (4) The phase transitions take place at 1.8 and 4 GPa in the crystal. Copyright © 2007 John Wiley & Sons, Ltd. [source]


Anomalous Dynamical Charge Change Behavior of Nanocrystalline 3C-SiC upon Compression

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2004
Haozhe Liu
Using diamond anvil cell (DAC) technique, in situ high-pressure Raman scattering and energy-dispersive X-ray diffraction (EDXRD) experiments were used at room temperature to study 3C-SiC with an average grain size of 30 nm. In contrast to its bulk counterpart, a decrease of the Born's transverse effective charge of these nanocrystals was observed with increasing pressure from measurements of the longitudinal and transverse optical phonon modes (longitudinal optical,transverse optical) splitting. This is therefore indicative of a diminishing ionicity of nanocrystalline 3C-SiC on compression. [source]


Heating effects of the matrix of experimentally shocked Murchison CM chondrite: Comparison with micrometeorites

METEORITICS & PLANETARY SCIENCE, Issue 1 2007
Naotaka TOMIOKA
However, if a major fraction of micrometeorites are produced by impacts on porous asteroids, they may have experienced shock heating before contact with the Earth's atmosphere (Tomeoka et al. 2003). A transmission electron microscope (TEM) study of the matrix of Murchison CM chondrite experimentally shocked at pressures of 10,49 GPa shows that its mineralogy and texture change dramatically, mainly due to shock heating, with the progressive shock pressures. Tochilinite is completely decomposed to an amorphous material at 10 GPa. Fe-Mg serpentine is partially decomposed and decreases in amount with increasing pressure from 10 to 30 GPa and is completely decomposed at 36 GPa. At 49 GPa, the matrix is extensively melted and consists mostly of aggregates of equigranular grains of Fe-rich olivine and less abundant low-Ca pyroxene embedded in Si-rich glass. The mineralogy and texture of the shocked samples are similar to those of some types of micrometeorites. In particular, the samples shocked at 10 and 21 GPa are similar to the phyllosilicate (serpentine)-rich micrometeorites, and the sample shocked at 49 GPa is similar to the olivine-rich micrometeorites. The shock heating effects also resemble the effects of pulse-heating experiments on the CI and CM chondrite matrices that were conducted to simulate atmospheric entry heating. We suggest that micrometeorites derived from porous asteroids are likely to go through both shock and atmospheric-entry heating processes. [source]


The local structure of ,-FeSi2 under high pressure

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2009
Yoshihisa Mori
Abstract We report the results of the high-pressure X-ray diffraction study and the high-pressure extended X-ray absorption fine structure study for ,-FeSi2 using the synchrotron radiation sources. The bond lengths of Fe,Fe, Si,Si, and Fe,Si under pressure were refined by the Rietveld method and the EXAFS analysis. It is interesting that the bond length of Si,Si is almost unchanged with increasing pressure. The DV-X, molecular orbital calculation was carried out for the crystal structure at 34.9 GPa and shows that the highest occupied molecular orbital consists of only 3d orbital of Fe atom. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Temperature and pressure dependence of carrier recombination processes in GaAsSb/GaAs quantum well lasers

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2007
Konstanze Hild
Abstract We investigated the temperature and pressure dependence of carrier recombination processes occurring in GaAsSb edge-emitting lasers operating near 1.3 ,m. Below ,100 K, the threshold current, Ith, is dominated by the radiative current, Irad, and is proportional to temperature, T. However, above 100 K, non-radiative recombination increases abruptly such that by 125 K it accounts for 40% of Ith. From high pressure measurements at this temperature, we find that the non-radiative current decreases with increasing pressure, consistent with the presence of Auger recombination. At room temperature, non-radiative recombination accounts for ,90% Ith and gives rise to a super-linear temperature dependence of Ith, in spite of the fact that Irad , T. At room temperature the non-radiative current increases with increasing pressure, indicating that under ambient operating conditions, the devices are also limited by carrier leakage into the ,-minimum of the GaAs barriers and possibly also into the X-minima of the GaAsP confining layers. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


X-ray diffraction study of amorphous phase of BaSi2 under high pressure

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2007
T. Nishii
Abstract A high-pressure synchrotron X-ray diffraction study of zintl phase BaSi2 semiconductor has been performed up to 45 GPa. The pressure-induced amorphization occurred at 13 GPa. In the amorphous phase, the Ba,Si bond distance decreased with increasing pressure, while the Ba,Ba bond distances were almost unchanged. The Rietveld refinement revealed that these distances in the crystal phase decreased with increasing pressure. By combining these results, the Ba,Si bond compressibility in both phases is almost identical. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]