1,574 research outputs found
“Demokratisches Vorbild trotz zunehmender sozialer Ungleichheit? Kolumbiens ambivalente sozialstrukturelle Entwicklung”
No full textNitz A, Wehrmann D. “Demokratisches Vorbild trotz zunehmender sozialer Ungleichheit? Kolumbiens ambivalente sozialstrukturelle Entwicklung”. Soziale Ungleichheit in den Amerikas: Historische Kontinuitäten und sozialer Wandel von der Mitte des 19. Jahrhunderts bis heute. KLA Working Paper Series No. 9.; 2013
Syntheses of Carbocyclic Analogues of α‑d‑Glucosamine, α‑d‑Mannose, α‑d‑Mannuronic Acid, β‑l‑Idosamine, and β‑l‑Gulose
No full textA versatile synthesis of orthogonally protected derivatives
of
carba-α-d-glucosamine, carba-α-d-mannose,
carba-α-d-mannuronic acid, carba-β-l-idosamine, and carba-β-l-gulose from methyl α-d-mannoside is described. Our synthetic strategy utilizes the
palladium-promoted Ferrier carbocyclization and persistent butane-2,3-diacetal
protection to produce a key chiral cyclohexanone intermediate, from
which all five carbasugar derivatives can readily be obtained
Development of Mono-de-N-acetylated β-(1→6)-N-acetyl-D-glucosamine Substrates for Characterization of PgaB Hydrolase Activity
No full textMany bacteria form biofilms, surface-attached communities embedded in an extracellular matrix, as a means for survival. The production of the partially de-N-acetylated poly-β-(1→6)-N-acetyl-D-glucosamine (dPNAG) exopolysaccharide is required for biofilm formation in many clinically relevant bacteria. The PgaABCD biosynthetic machinery is responsible for the synthesis and export of dPNAG in Gram-negative bacteria. PgaB is a two-domain periplasmic protein that processes PNAG prior to its export to the extracellular space. ΔpgaB strains have an impaired biofilm-forming phenotype, making PgaB a potential therapeutic target. The N-terminal domain of PgaB is a family 4 carbohydrate esterase that partially de-N-acetylates PNAG. The C-terminal domain is a family 153 glycoside hydrolase whose role in vivo is not fully understood. This domain can degrade dPNAG-based biofilms, demonstrating the potential for the enzyme to be used as a therapeutic treatment for biofilm-mediated infections. It is known that the PgaB C-terminal domain is active on dPNAG, but further characterization of the enzyme’s activity, substrate specificity, and mechanism of hydrolysis has been hampered by a lack of pure mono-de-N-acetylated β-(1→6)-N-acetyl-D-glucosamine (GlcNAc) oligosaccharides to be used as substrates. This thesis describes the synthesis of defined mono-de-N-acetylated β-(1→6)-GlcNAc penta- and hepta-saccharides by using a convergent synthetic method and a multistep selective deprotection. These synthetic oligosaccharides were validated as Bordetella bronchiseptica PgaB C-terminal domain substrates through the development of a fluorescence-based thin-layer chromatography (TLC) assay. Mass spectrometry experiments and nuclear magnetic resonance (NMR) spectroscopy analysis provided further insights into the requirements for substrate recognition and mechanism of hydrolysis. These results are consistent with the previously reported observations that the site of de-N-acetylation drives the selectivity of hydrolysis by PgaB.Ph.D
Development of Mono-de-N-acetylated β-(1→6)-N-acetyl-D-glucosamine Substrates for Characterization of PgaB Hydrolase Activity
No full textMany bacteria form biofilms, surface-attached communities embedded in an extracellular matrix, as a means for survival. The production of the partially de-N-acetylated poly-β-(1→6)-N-acetyl-D-glucosamine (dPNAG) exopolysaccharide is required for biofilm formation in many clinically relevant bacteria. The PgaABCD biosynthetic machinery is responsible for the synthesis and export of dPNAG in Gram-negative bacteria. PgaB is a two-domain periplasmic protein that processes PNAG prior to its export to the extracellular space. ΔpgaB strains have an impaired biofilm-forming phenotype, making PgaB a potential therapeutic target. The N-terminal domain of PgaB is a family 4 carbohydrate esterase that partially de-N-acetylates PNAG. The C-terminal domain is a family 153 glycoside hydrolase whose role in vivo is not fully understood. This domain can degrade dPNAG-based biofilms, demonstrating the potential for the enzyme to be used as a therapeutic treatment for biofilm-mediated infections. It is known that the PgaB C-terminal domain is active on dPNAG, but further characterization of the enzyme’s activity, substrate specificity, and mechanism of hydrolysis has been hampered by a lack of pure mono-de-N-acetylated β-(1→6)-N-acetyl-D-glucosamine (GlcNAc) oligosaccharides to be used as substrates. This thesis describes the synthesis of defined mono-de-N-acetylated β-(1→6)-GlcNAc penta- and hepta-saccharides by using a convergent synthetic method and a multistep selective deprotection. These synthetic oligosaccharides were validated as Bordetella bronchiseptica PgaB C-terminal domain substrates through the development of a fluorescence-based thin-layer chromatography (TLC) assay. Mass spectrometry experiments and nuclear magnetic resonance (NMR) spectroscopy analysis provided further insights into the requirements for substrate recognition and mechanism of hydrolysis. These results are consistent with the previously reported observations that the site of de-N-acetylation drives the selectivity of hydrolysis by PgaB.Ph.D
The role of draft facets in temperature effects in silicone-on-glass Fresnel lens applications
No full textHopelessness and high risk parenting attitudes in relation to child abuse and neglect
No full textPlan BA review of the literature indicates the relationship between hopelessness and depression in adolescent females is significant. The problem of hopelessness as a component of depression is explored in this study, as is the correlation between hopelessness and high risk parenting attitudes in teenage girls. According to a study by Lamb and Nitz (1991), approximately one million teenage girls become pregnant each year. Adolescents who become parents may experience added stress, which may result in child abuse and neglect. Child abuse and neglect is at an all time high in our country, and is surely a national crisis. The Child Abuse Prevention, Adoption and Family Services Act of 1988 (Public Law 93-247) defines abuse and neglect as “the physical or mental injury, sexual abuse or exploitation, negligent treatment or maltreatment of a child under the age of 18 by a person who is responsible for the child’s welfare under circumstances which indicate that the child’s health or welfare is harmed or threatened” (Bavolek, 1990). This study will acknowledge and discuss the importance of identifying and treating hopelessness in teenage mothers. Rust (1999) indicates teenage mothers are at increased risk for depression and high risk parenting attitudes in relation to child physical abuse. Therefore, the purpose of this study is to correlate hopelessness and high risk parenting attitudes in teenage parents. There is a great amount that can be learned from this study, and research suggests that child abuse and neglect and the problems associated with this issue are not going away, they are at epidemic proportions, despite the increased interventions of the last ten years. This study is pertinent in today’s world and can provide insight into reducing the incidents of child abuse and neglect. The purpose of this study is to assess the degree of correlation between hopelessness in adolescent females and high risk parenting attitudes. For the purpose of this study, thirty adolescent females were asked to complete the Beck’s Hopelessness Scale and Adult-Adolescent Parenting Inventory (AAPI-2), [Bavolek,1999]. Upon completion of the study, a significant degree of correlation was not found between hopelessness in adolescent females and high risk parenting attitudes
Adsorption and Absorption Energies of Hydrogen with Palladium
No full text[Image: see text] Thermal recombinative desorption rates of HD on Pd(111) and Pd(332) are reported from transient kinetic experiments performed between 523 and 1023 K. A detailed kinetic model accurately describes the competition between recombination of surface-adsorbed hydrogen and deuterium atoms and their diffusion into the bulk. By fitting the model to observed rates, we derive the dissociative adsorption energies (E(0, ads)(H(2)) = 0.98 eV; E(0, ads)(D(2)) = 1.00 eV; E(0, ads)(HD) = 0.99 eV) as well as the classical dissociative binding energy ϵ(ads) = 1.02 ± 0.03 eV, which provides a benchmark for electronic structure theory. In a similar way, we obtain the classical energy required to move an H or D atom from the surface to the bulk (ϵ(sb) = 0.46 ± 0.01 eV) and the isotope specific energies, E(0, sb)(H) = 0.41 eV and E(0, sb)(D) = 0.43 eV. Detailed insights into the process of transient bulk diffusion are obtained from kinetic Monte Carlo simulations
Dissertatio Juridica De Duobus Circa Idem Factum Concurrentibus
No full textZugl.: Halle, Univ., Jur. Diss., 1714Quam In Illustri Academia Fridericiana, Praeside Dn. Jacobo Friderico Ludovici, J. U. D. & Prof. Publ. Ordin. Ad Diem Octobr. MDCCXIV. Placido Eruditorvm Examini Submittit Johannes Nitz, Stargardia Pomeranus.Tag d. Promotion nicht in der VorlageAutopsie nach Ex. der ULB Sachsen-AnhaltVorlage des Erscheinungsvermerks: Halae Magdeburgicae Typis Joan. Christ. Grunerti, Acad. Typogr. Recusa MDCCXLII
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