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  • 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.
1

The Study of CuInSe2 Solar Cell

Lin, Yu-Chien 27 July 2001 (has links)
none
2

Status and control of coffee berry disease in Malawi

Phiri, Noah Anthony January 2000 (has links)
No description available.
3

The hazard of sinkholes formation in the Centurion CBD and surrounding areas : Pretoria, Gauteng

Oosthuizen, Anna Catharina 15 May 2013 (has links)
The greater part of land in the area south of Pretoria is underlain by dolomite from the Chuniespoort Group of the Transvaal Supergroup. In South Africa dolomite rock has a notorious reputation for the formation of sinkholes and subsidences. Thousands of people reside and work in the Centurion area, where numerous sinkholes have occurred causing damage and in some instances loss of property. Centurion has rapidly densified over the last 40 years. This study deals with the hazard of sinkhole formation in the Centurion CBD and surrounding area as well as comparing the Method of Scenario of Supposition by Buttrick and van Schalkwyk (1995) based on an ‘abused’ land use situation to this ‘managed’ area in Centurion. Various classification systems have been proposed since the 1970’s in an attempt to evaluate the stability of sites on dolomite in South Africa and a summary of each are provided in the dissertation. The classification system that is currently used in South Africa is the method proposed by Buttrick (1992) which is known as the Method of Scenario Supposition. A total of 119 sinkholes have been recorded in the Centurion CBD area since the early 1970’s. Three lives havebeen lost as a result of a sinkhole in the area and a total of seven houses or units had to be demolished. Draft guidelines for allocation of each hazard class has been developed, which is referred to as the proposed ‘Modified Method of Scenario Supposition’. This is mainly based on the dolomite bedrock depth and the mobilization potential of the overlying horizons. Eight Inherent Hazard Classes are present which classify an area into having a low, medium or high hazard of sinkhole formation. After each borehole was assigned its specific inherent hazard class, the information was recorded in ESRI ArcGIS® software. The Spatial Analyst® extension of ArcMap® was used to create a map showing the areas of low, medium and high hazard of sinkhole formation. The map generally indicates a medium to high susceptibility to sinkhole formation in the Centurion CBD area with pockets of low hazard areas. This hazard map was then used to make recommendations for each of the eight Inherent Hazard Classes on suitable development types as per the draft SANS 1936-1:2012 guidelines. Various methods are used to calculate the hazard of sinkhole formation using data such as the historicaloccurrence of sinkholes, geological information and the hazard map. These results are used to compare this ‘managed land’ to the ‘abused land’ scenario used by Buttrick and van Schalkwyk (1995). Overall, the hazard for sinkhole formation in the Centurion CBD area does not correlate well with the method proposed by Buttrick and van Schalkwyk (1995). According to the anticipated number of events by Buttrick and van Schalkwyk far more sinkholes should have occurred in the high hazard areas. In contrast, the most sinkholes in the Centurion CBD area occurred in the areas classified as having a medium hazard for sinkhole formation. / Dissertation (MSc)--University of Pretoria, 2013. / Geology / unrestricted
4

Synthesis of methyl decanoate using different types of batch reactive distillation systems

Aqar, D.Y., Rahmanian, Nejat, Mujtaba, Iqbal M. 22 March 2017 (has links)
Yes / Methyl Decanoate (MeDC) is a Fatty Acid Methyl Ester (FAME) and is an important chemical compound with global production of 31 million tons per year. However, synthesis of methyl decanoate (MeDC) via esterification of Decanoic Acid (DeC) with methanol by reactive distillation is operationally challenging due to difficulty of keeping the reactants together in the reaction zone as methanol being the lightest component in the mixture can separate itself easily form the other reactant deteriorating significantly the conversion of DeC using either conventional batch or continuous distillation column. This is probably the main reason for not applying the conventional route for MeDC synthesis. Whether Semi-batch Distillation column (SBD) and the recently developed Integrated Conventional Batch Distillation column (i-CBD) offer the possibility of revisiting such chemical reactions for the synthesis of MeDC is the focus of this paper. The minimum energy consumption (Qtot) as the performance measure is used to evaluate the performances of each of these reactive column configurations for different range of methyl decanoate purity and the amount of product. It is observed that the use of i-CBD column provides much better performance than SBD column in terms of the production time and the maximum energy savings when excess methanol is used in the feed. However, the SBD column is found to perform better than the i-CBD column when both reactants in the feed are in equal amount. Also, the optimization results for a given separation task show that the performance of two-reflux intervals strategy is superior to the single-reflux interval in terms of operating batch time, and energy usage rate in the SBD process at equimolar ratio.
5

Výběr chemotypů konopí vhodných pro léčebné použití s převládající účinnou látkou THC / Selection of cannabis chemotypes suitable for therapeutic use with predominant active substance THC

Michnová, Lenka January 2016 (has links)
During recent years the possible medical application of cannabis has been discussed more and more. It turns out, that the active substances (cannabinoids cannabidiol and tetrahydrocannabinol) have a significant potential in medicine and do not have to be only misused as a recreational drug. The Department of Crop Production (Faculty of Agrobiology, Food and Natural Resources) is the first institution with granted permission to legally cultivate cannabis, with higher THC content than 0,3 %, for research purposes. The first part of literate review recapitulates the basic knowledge about the cannabis, its biologically active substances and current legislation. The second part describes the endocannabinoid system and utilization of cannabis in the field of medicine. This thesis aims to evaluate the THC and CBD content in seven different cannabis cultivar strains (Nurse Jackie, Conspiracy Kush, Jillybean, Jack Cleaner 2, Jack Skellington, Nordle and National Health Service). The cannabis plants were cultivated in three cultivation cycles. The content of active substances in dried and homogenised inflorescence was analysed by gas chromatography with flame ionization detection (GC-FID) according to UN methodology. Based on the analysis, the appropriate genotypes were chosen, which are in accordance of Regulation 236/2015 Sb. and needs of the patients. According to results it was found, that all seven analysed cultivars are suitable for medical utilization regarding the content of THC and CBD. The highest average content of THC was measured by cultivar Jack Cleaner 2. On the other hand, the lowest THC content was established by cultivar Nordle. It was demonstrated, that the differences in THC content are connected rather to genotype variation than cultivation factors. The main goal of the thesis was to discover which of the seven cultivars will be stable regarding not only THC and CBD content, but also the crop yield. In those regards the research shows the cultivar Jack Cleaner 2 and Nurse Jackie as the most suitable. Preliminary results indicate that these two cultivar strains would be the most suitable for the therapeutic purposes.
6

Ammonia free CdS buffer layerfor Cu(In,Ga)Se2 solar cells by chemical bath deposition

Hedlund, Daniel January 2013 (has links)
The buffer layer in Cu(In,Ga)Se2 solar cells can improve cell performance. In this work we make CdS buffer layer by chemical bath deposition (CBD) without ammonia. CBD without ammonia were sought out since ammonia is a volatile compound. Different recipes for making CdS were tested; only one of the tested recipes actually produced something that is worth further investigating. This recipe used sodium citrate, an innocuous compound instead of ammonia. The best performance was 0.15 % off from the reference.This is almost as good as the used baseline process. However the worst almost completely killed the solar cells. Cell performance dropped by more than absolute 10 %. This demonstrates that chemical bath deposition can have profound effects on the solar cell performance. When trying to improve the best cells only detrimental effects showed up. This might show that, a part in the recipe used, NaOH has detrimental effects on solar cells. Ammonia free chemical bath deposition is possible, however so far it has not produced as good results as the reference. The difference is however very small, which makes it worth further investigating with moreand better solar cell material.
7

Exploring the relationship between cannabis and panic

Ward, David John Deen January 2010 (has links)
1.1 Background: Despite Cannabis being the most widely used recreational drug in the western world (Earlywine, 2002) little is known about its potential association with anxiety and panic pathology. 1.2 Literature Review: A systematic literature review was conducted with twenty-nine studies critically reviewed. Papers suggested contradictory and equivocal results across all research designs and anxiety disorders. Whilst a significant number of studies have observed an association between cannabis and anxiety/anxiety disorders, the nature and direction of that association is still a point of contention. 1.3 Research Report: No known British empirical research has focused on exploring relationships between cannabis and panic attacks. Also no known research has investigated the differential effects of consuming different types of cannabis on panic pathology. Inspired somewhat on established research (e.g. Zolvensky et al., 2006a) a cross-sectional study was undertaken to explore the potential relationship between cannabis and anxiety. A self-selecting opportunity sample of 306 students drawn from both of Leicester’s universities completed a battery of questionnaires concerning cannabis use, tobacco use, panic attack history, alcohol use, poly-substance use and various psychometrics. Significant levels of both cannabis use and panic attack history were reported among the sample. Survival analysis revealed cannabis users were of significant increased risk (OR 2.01) of experiencing a panic attack compared to non-users. Mann-Whitney analysis found cannabis users who use mainly high potency ‘sensimillia’ experienced significantly more lifetime panic attacks than those who used other types. Limitations are explored. 1.4 Implications: The research report concludes that cannabis use is a risk factor in experiencing panic attacks and experiencing more lifetime attacks. High potency cannabis further increases this risk. Education for substance misuse and mental health professionals is recommended along with cannabis use forming part of assessment for panic attacks/disorder. 1.5 Critical Appraisal: Reflective appraisal of the research process is presented alongside key learning points.
8

Vliv externích faktorů na produkci vybraných sekundárních metabolitů u konopí

Palíšek, Ondřej January 2017 (has links)
Presented diploma thesis is focused on production of secondary metabolites under influence of external factors.in cannabis (Cannabis sativa L.). Theoretival part contains phylogenetical, morphological and botanical characterization of the given species. The part is further expanded by description of major cannabis constituents and their biosynthetic pathways. In the end of the chapter, methods for elicitation are described. Main goal of the experimental part was to compare influence of vaious fertilizers and product containing coloid silver on morphological characteristics and selected secondary metabolites content. Highest yield was observed within plants fertilized by Powder Feeding. Highest THC content was observed in plants fertilized by Jungle in da Box. Variation of height, yield and secondary metabolites within experimental population was observed, however was not statistically conclusive. Influence of Altron Silver was not statistically proven.
9

Vliv skladování na změny obsahových látek konopí

Vomáčka, Vít January 2017 (has links)
This thesis deals with the effect of storage of cannabis on the level of content of its active substances. The theoretical portion focuses on a botanical characteristics sum-mary. It further describes the growing needs and options of cannabis on the fields and of medical cannabis in covered areas. Portion of the thesis deals with the use of each individual parts of the cannabis plant. The thesis contains detailed description of canna-binoids and other substances. It further describes the effect of individual external factors on the stability of cannabinoids in cannabis products. The last part of the theore-tical section deals with the ability to analyze cannabinoids. The goal of the experimental section was to discover effects of different type of storage on the level of content of cannabidiol and delta-9-tetrahydrocannabinol in cannabis samples. The setting included a gas chromatograph GC Fisons instruments with FID detector. These samples were regularly collected and ex-tracted during the period of one year. Retention periods of individual cannabinoids and calibration curves were created. The results showed a reduction of cannabinoids in higher temperatures. The results further confirmed storage of vacuumed materials at -20 °C temperature as the most appropriate type of storage for female inflorescence of can-nabis.
10

Strategier kring vakanser på kontorsmarknaden / Strategies on vacancies in the office market

Tjernberg, Erik January 2013 (has links)
Det har alltid funnits tomma och outhyrda lokaler i Stockholm. Vakanser är något som alltid har funnits, och därför också känns som ett ständigt aktuellt ämne. Fastighetsföretag har alltid försökt se till att så mycket som möjligt av lokalerna är uthyrda, men vilka strategier finns och används vid frågor om vakans? Studien undersöker vad som sägs på marknaden i Stockholm. Med hjälp av intervjuer av ansvariga inom detta ämne hos olika kommersiella fastighetsföretag har en bild med tankar och åsikter från dessa personer målats upp för att få en inblick i vad som är viktigt att tänka på när det gäller vakanser. En enkät har också skickats ut för att få en bredare uppfattning hur de kommersiella fastighetsföretagen agerar i olika situationer, vilken strategi kring vakanser de har. Företagen har samma åsikt om hel del frågor. De är överrens om att det finns mycket pengar att tjäna genom att se till att den nuvarande hyresgästen sitter kvar i lokalen. Att få in en ny hyresgäst i lokalen går inte att göra på en dag. Det kan ta månader innan den nya hyresgästen är på plats, och vakanser är lika med förlorade pengar. Det är därför viktigt att ha en bra relation med sin hyresgäst. De frågor som ställdes som fick olika svar var bland annat hur företagen agerar för att påverka antalet lediga lokaler, vad som görs vid uppsägning av kontrakt, vad man tycker om hyresgästrepresentanter, hur de ser på ett eventuellt priskrig, varför man inte har 100 % uthyrda lokaler, hur man ser på dold vakans och vilka lokaler som är mest efterfrågade i Stockholm, På de flesta frågor har en klar majoritet av uthyrarna samma åsikt. Ingen uthyrare ger några stora rabatter till hyresgästerna. Uthyrarna vet att det är dyrt att flytta. Det finns heller inget som tyder på att en uthyrare skulle sänka sina priser bara för att en konkurrent gör det, och på sätt hamna i ett priskrig. De flesta uthyrare tycker det är skönare att förhandla direkt med hyresgästen istället för att gå genom en hyresgästrepresentant. Vilka parametrar som är viktigast i en lokal, får många olika svar i undersökningen. Nya lokaler och möjlighet att skapa rum och ny planlösning är de populäraste svaren. Få företag oroar sig för att det ska bli en högre vakansgrad i närmaste framtiden. De flesta tror att marknaden kommer vara oförändrad. / There have always been empty and vacant premises in Stockholm. Vacant space is something that has always existed, and therefore feels like a recurring topic. Property companies has always tried to ensure that as much as possible of the premises are leased, but what strategies are in place in the issues of vacancy? The study examines what is said in the market in Stockholm. Using interviews of people responsible in this line of work from various commercial real estate companies, by studying and analyzing thoughts and opinions of what these people have to say get a glimpse of what's important to think about in terms of vacancies. A survey was also sent out to get a wider understanding of how the commercial real estate firms act in different situations, the strategy around the vacancies they have. Companies have the same opinion on many questions. They agreed that there is much money to be made by ensuring that the current tenant remains in the premises. Getting a new tenant into the premises can´t be done in a day. It can take months before the new tenant is in place, and vacancies mean lost money. It is therefore important to have a good relationship with his tenant. On most issues, a clear majority of the property companies have the same opinion. No company provides big discounts. They know it's expensive to move. There is also no evidence to suggest that a company would lower their prices just because a competitor does, and end up in a price war. Most companies find it more comfortable to negotiate directly with the tenant instead of going through a tenant representative. The answers differ on what parameters are most important in an office space. The most popular answers are new spaces and the ability to make a new floor plan Very few companies worry about if there will be a higher vacancy rate in the near future. Most believe that the market will remain unchanged.

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