• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 272
  • 221
  • 54
  • 38
  • 30
  • 30
  • 8
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • Tagged with
  • 783
  • 721
  • 350
  • 151
  • 96
  • 76
  • 72
  • 72
  • 60
  • 57
  • 56
  • 53
  • 50
  • 45
  • 44
  • 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.
91

Quantificação do ácido lático na fermentação etanólica como parâmetro de monitoramento do processo /

Ventura, Ricardo. January 2007 (has links)
Resumo: O ácido lático foi quantificado no processo produtivo de várias destilarias do estado de São Paulo, com ênfase na fermentação, onde esse produto representa perdas de rendimento e afeta o metabolismo da levedura. As análises foram realizadas por meio de aparelhos dotados de tecnologia de enzima imobilizada, específicos para o isômero L(+) lactato e os resultados correlacionados com outros parâmetros do processo, obtidos pelas análises usuais. Na cana colhida, o teor de ácido lático variou entre 10,0 a 297,0 mg/L, de acordo com estágio de deterioração da matéria-prima. Nas destilarias anexas à fábrica de açúcar, o ácido lático foi detectado desde o caldo extraído nas moendas, onde se observou valor mínimo de 10 mg/L, até o mel final, no qual verificou-se teor superior a 8.800 mg/L. Nas fermentações contínuas registraram-se as maiores produções de ácido lático, superando 3700 mg/L - equivalente a mais de 6% (m/v) do álcool produzido, enquanto que em batelada alimentada conseguiu-se manter teores ao redor de 300 mg/L por 16 ciclos fermentativos. Bactérias isoladas de diferentes destilarias, e inoculadas individualmente em fermentações em laboratório, produziram quantidades distintas de ácido lático, de acordo com a espécie. Essa metodologia também foi empregada na avaliação da eficácia dos antibacterianos, usados freqüentemente nas destilarias brasileiras. Em fermentações tratadas com produtos específicos, a diminuição da atividade bacteriana determinou a queda na produção de ácido lático em mais de 70% em um ciclo fermentativo. / Abstract: The lactic acid was quantified in the ethanol production process of several distilleries of São Paulo State, especially in fermentation, where such product represents low yield and affects the metabolism of the yeast. The analysis were performed by equipments based on immobilized enzyme technology, specific for the isomer L(+) lactate and the results were correlated with others process parameters, got by the current methods. In the harvested cane, the lactic acid content varied from 10,0 to 297,0 mg/L, according to the deterioration of the raw material. In distilleries inside sugar factories, the lactic acid was quantified since the juice from crushers, where the registered values range from minimum of 10 mg/L until the molasses, in which values up to 8.800 mg/L were found. In the continuos fermentation it was registred the highest amount of lactic acid, up to 3.700 mg/L, corresponding to more than 6% of ethanol produced, while in fed batch it kept around 300 mg/L for 16 fermentaion cicles. Isolated from different distilleries, inoculated in laboratory fermentations, produced distinghished amount of lactic acid, according to the species. The method proposed also was used in the evaluation of efficacy of bactericidal, commonly used in the Brazilian distilleries. In fermentation treated with specific products, the reduction of bacterial activity leads the drop of lactic acid production up to 70% in one fermentation cicle. / Orientador: Dejanira de Franceschi de Angelis / Coorientador: Jonas Contiero / Banca: Octavio Antonio Valsechi / Banca: Marcia Justino Rossini Mutton / Mestre
92

Akutní komplikace diabetu a jeho následky / Acute complications of diabetes mellitus and it's sequel

Frank, Adrianna Natalie January 2010 (has links)
The basis of this thesis is intended to inform the reader about the general complications of acute diabetes mellitus and its consequences. It focuses on the general definitions of the diseases, etiology, morbidity, mortality, pathogenesis of the disease, clinical presentation, treatment, and future developments in hopes of treating the disease. The major focus highlights the differences between diabetic ketoacidosis and hyperglycemic hyperosmolar state, as well as understanding the complications of diabetic hypoglycemia. The most critical effects of these disorders are also emphasized; cerebral edema, vascular thrombosis, and hyperchloremic metabolic acidosis.
93

Poultry feeds prepared from fermented prawn waste silage

De Silva, Lekamwasam L. S. S. K. January 1998 (has links)
The use of shrimp processing waste with other cheap raw materials such as cassava was studied as a potential low cost animal feed, specially in developing countries. The impact on the economies of the shrimp industry and possible effects on the environmental were taken into consideration in developing the project.
94

A study of the efficacy of homoeopathic treatment in controlling lactic acid accumulation and exercise fatigue

La Grange, Colin David January 1999 (has links)
Dissertation submitted in compliance with the requirements for the Master's Degree in Technology: Homoeopathy, Technikon Natal, 1999. / The action of homoeopathic medicine on physiological processes is poorly understood. It is hypothesized that homoeopathic potencies of Sarcolactic acid could have an effect in increasing the metabolism of lactate in the body, lowering its concentration change due to exercise, and thus reduce exercise fatigue. There is a need to investigate whether a homoeopathic remedy made from a physiological chemical can influence the action of this chemical in the body. Much has been done on the influence of homoeopathy on toxins, and their detrimental effects, but little is known of its effects 0(1 metabolic by-products and the influence of hqmoeopathy on their regulation / M
95

Exploration of Bis(imino)pyridine Iron Alkoxides for the Synthesis of Novel Degradable Polymers

Delle Chiaie, Kayla R. January 2018 (has links)
Thesis advisor: Jeffery A. Byers / This dissertation discusses the development of a family of iron complexes and their role in the synthesis of degradable polymers. Chapter one will introduce the different areas of redox-switchable polymerization. In chapter two the synthesis of block copolymers containing a polyester and polyether block is presented. The application redox-switchable polymerization to form a copolymer with two fundamentally distinct backbone functionalities and their characterization is discussed. In chapter three the synthesis of a degradable cross-linked polymer through a novel redox-triggered cross linking event is summarized. In chapter four, a detailed mechanistic study of iron-complex catalyzed epoxide polymerization is examined and a unique mechanistic scheme is proposed. Lastly, in chapter five the synthesis and characterization of a formally iron(I) complex is presented. This complex shows remarkable catalytic activity towards ring-opening polymerization. / Thesis (PhD) — Boston College, 2018. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.
96

Innate immune responses of vaginal epithelium and activity of monoclonal antibody-based microbicide in the presence of lactic acid, a lactobacillus metabolite

Bayigga, Lois 17 June 2016 (has links)
Sexually transmitted infections (STIs) such as gonorrhea, herpes simplex virus 2 (HSV 2), hepatitis C, human papilloma viruses (HPV) and human immunodeficiency virus type 1 (HIV) are a global health concern affecting millions of lives. Although extensive efforts have been geared towards prevention and treatment of STIs, little progress has been achieved. Recently, efforts to develop microbicides have been focused on the commensal bacterial species that comprise the vaginal microbiome and their role in immunity and disease pathogenesis. The lower FRT which includes the cervix and vagina has endogenous bacterial species that are supported by the mucosal epithelium. Lactobaccilli are the dominant endogenous bacterial species in the vagina of most women; lactobacilli convert glycogen to lactic acid (LA) which maintains a low pH environment in the vagina and serves as a deterrent to infectious organisms. The purpose of this research project was to determine the effects of LA on vaginal integrity and inflammation in a vaginal epithelial cell (VEC) tissue model, and on the ability of the broadly neutralizing anti-HIV antibody, VRCO1, to inactivate HIV in vitro. Effects of LA exposure on the viability and integrity of vaginal epithelium were determined by histology, MTT assay and measurement of transepithelial electric resistance (TEER). In addition, an enzyme-linked immunosorbent assay (ELISA) was used to measure concentrations of cytokines secreted by the VEC epithelial cells in response to different doses of LA. Using TLR agonists to simulate infection in the VEC model, we tested the hypothesis that LA has anti-inflammatory properties that modulate immune responses of the vaginal epithelium. We assessed the effect of LA on the neutralization activity of the anti-HIV-1 monoclonal antibody VRCO1 in the TZM-bl HIV neutralization assay. Tissue morphology and integrity were not affected by exposure to LA. Low concentrations of IL-1β and RANTES were expressed by VEC tissues in response to L-LA treatment. VEC tissues expressed significantly elevated concentrations of IL-1RA (p<0.0001), an anti-inflammatory cytokine, in response to LA regardless of incubation time and LA doses. In addition, treatment of VEC tissues with Poly I: C in the presence of LA dampened upregulated expression of IL-1β, TNF-alpha and IL-6 in response to the TLR 3 agonist. LA also elicited significantly higher IL-1RA concentrations when apically added to the TLR agonist-treated VEC tissues. These data suggest that LA elicits an anti-inflammatory response in the vaginal epithelium. LA acidic conditions as low as pH 3.5 did not affect the ability of VRC01, to prevent HIV infection. We found that LA, at concentrations present in vaginal secretions of normal women, inhibited the inflammatory response to a TLR agonist, possibly due to upregulated Il-1RA synthesis. In addition, the functionality of VRCO1 in an acidic milieu was not diminished, providing evidence that antibodies can function in the low pH vaginal environment. This report highlights the potential use of LA in the vagina as a microbicide due to its virucidal activity and anti-inflammatory properties. It also indicates that monoclonal antibody-based vaginal microbicides will not be neutralized by LA. There is still a need to elucidate the exact mechanisms by which LA confers immuno-modulatory properties within the female reproductive tract.
97

Effects Of Lactic Acid And Cetylpyridinium Chloride As Immersion Treatments To Reduce Populations Of Salmonella Typhimurium Attached On Ready-To-Eat Shrimp

Kim, Hyejin 15 December 2007 (has links)
Salmonella enterica Typhimurium is a common foodborne pathogen, and ready-to-eat (RTE) seafood is a potential source of Salmonella outbreaks. Lactic acid is a classical preservative in the meat industry and it is used with high efficacy to sanitize meat surfaces. Cetylpyridinium chloride (CPC) is a cationic quaternary ammonium compound proposed for use as a pathogen intervention substance. Cetylpyridinium chloride activity can be potentially affected by interactions between cetylpyridinium chloride and lactic acid. Lactic acid treatment (up to 1%) reduced Salmonella Typhimurium counts by less than 0.5 log cfu/g. Cetylpyridinium chloride treatment (up to 1%) reduced Salmonella Typhimurium counts by 0.9 log cfu/g. Cetylpyridinium chloride treatment at 18 and 45°C reduced populations of Salmonella Typhimurium by 1.34 and 1.14 log cfu/g. Combined treatment with cetylpyridinium chloride and lactic acid at 18 and 45°C decreased Salmonella Typhimurium counts by 0.83 log cfu/g and 1.05 log cfu/g. The single intervention of cetylpyridinium chloride was more effective than lactic acid used alone or combination of cetylpyridnium chloride and lactic acid to reduce Salmonella Typhimurium attached on ready-to-eat shrimp.
98

Antimicrobial effect of yogurt lactic acid bacteria and muscadine products on Enterobacter sakazakii

Weng, Weiien 13 December 2008 (has links)
Enterobacter sakazakii has been associated with powdered infant formula outbreaks which caused high mortality rate illnesses in infants in recent years. Current research was mainly focused on searching for natural antimicrobial agents which may be incorporated into baby foods to control this emerging pathogen. Yogurt and muscadine products were used in this study. The antimicrobial effects of yogurt were evaluated on agar plates and in a simulated gastrointestinal model. In the agar spot tests, diluted yogurt sample containing lactic acid bacteria at 106 CFU/mL was antagonistic toward E. sakazakii. However, the antimicrobial effect of yogurt on E. sakazakii in the simulated GI model was not noted. Certain numbers of tested E. sakazakii and lactic acid bacteria in yogurt were able to survive the acidic gastric condition and recovered in the intestinal model. By measuring the viable E. sakazakii cells in liquid cultures, the strong antimicrobial activities of muscadine juices and muscadine seed extracts were demonstrated. Within two hours, all inoculated E. sakazakii at 106 CFU/mL were decreased to non-detectable level. Juice and seed extract from dark-skinned muscadine demonstrated stronger antimicrobial activities than those form white-skinned muscadine. The characteristics of muscadine juices and seed extracts were also analyzed. The high phenolics and organic acid contents, such as ellagic, gallic, tannic, and tartaric acids in muscadine were correlated to the inhibitory effect observed.
99

The effects of pursed-lip breathing and added expiratory resistances on arterialized-venous blood gases and lactic acid /

Kinker, James Robert January 1986 (has links)
No description available.
100

Lactic acid purification of chitin from prawn waste using a horizontal rotating bioreactor

Zakaria, Zainoha January 1997 (has links)
Shellfish waste obtained from seafood processing plants contains chitin, protein and calcium carbonate. Chitin is a versatile biopolymer with many applications. Conventionally, chitin is separated from calcium carbonate and protein by acid and alkali respectively. In this project, a biotechnological approach was applied to recover chitin from scampi (Nephrops norvegicus) waste using lactic acid bacteria (LAB) to produce lactic acid from glucose which lowers the pH of the mixture, thus preserving the waste from spoilage. The acid also dissolves the calcium carbonate and under these conditions native enzymes breakdown the protein (autolysis), thus affording a substantial amount of purification of chitin. LAB were isolated and identified from various shellfish waste fermentations. Studies on their acid-producing ability revealed a few potentially good strains, identified as Lactobacillus paracasei, Lactobacillus plantarum and Pediococcus sp. The strain of Lactobacillus paracasei was used as a starter culture in the fermentation of shellfish waste in a horizontal rotating bioreactor in order to evaluate the feasibility of the process. The design of the bioreactor was such that it enabled separation of solid and liquid end products during fermentation. Several important fermentation parameters were studied including mode of rotation, concentration of glucose, temperature, rotation rates, loading capacity, type and particle size of waste. Partial purification of the scampi waste was achieved using both batch and fed batch operation, but in the latter, improved purification was achieved at the cost of increased glucose consumption and extended fermentation times. Whilst higher temperatures increased the rates of fermentation, higher rotation rates seemed to have the reverse effect. Mincing the waste helped to increase breakdown of protein whilst larger particles tended to undergo rapid spoilage. Analysis of the chitin product enabled this method to be compared with the conventional method. The results obtained showed that this method is capable of saving large volumes of chemicals and besides producing chitin, the protein liquor by-product could also be used as an ingredient in an animal feed which is not possible by the conventional method.

Page generated in 0.0236 seconds