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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

A Method For Three Dimensional Modelling Of Polypeptide Chains

Das, Ujjwal Kumar 07 1900 (has links) (PDF)
No description available.
2

Investigating Molecular Structures: Rapidly Examining Molecular Fingerprints Through Fast Passage Broadband Fourier Transform Microwave Spectroscopy

Grubbs, Garry Smith, II 05 1900 (has links)
Microwave spectroscopy is a gas phase technique typically geared toward measuring the rotational transitions of Molecules. The information contained in this type of spectroscopy pertains to a molecules structure, both geometric and electronic, which give insight into a molecule's chemistry. Typically this type of spectroscopy is high resolution, but narrowband ≤1 MHz in frequency. This is achieved by tuning a cavity, exciting a molecule with electromagnetic radiation in the microwave region, turning the electromagnetic radiation o, and measuring a signal from the molecular relaxation in the form of a free induction decay (FID). The FID is then Fourier transformed to give a frequency of the transition. "Fast passage" is defined as a sweeping of frequencies through a transition at a time much shorter (≤10 s) than the molecular relaxation (≈100 s). Recent advancements in technology have allowed for the creation of these fast frequency sweeps, known as "chirps", which allow for broadband capabilities. This work presents the design, construction, and implementation of one such novel, high-resolution microwave spectrometer with broadband capabilities. The manuscript also provides the theory, technique, and motivations behind building of such an instrument. In this manuscript it is demonstrated that, although a gas phase technique, solids, liquids, and transient species may be studied with the spectrometer with high sensitivity, making it a viable option for many molecules wanting to be rotationally studied. The spectrometer has a relative correct intensity feature that, when coupled with theory, may ease the difficulty in transition assignment and facilitate dynamic chemical studies of the experiment. Molecules studied on this spectrometer have, in turn, been analyzed and assigned using common rotational spectroscopic analysis. Detailed theory on the analysis of these molecules has been provided. Structural parameters such as rotational constants and centrifugal distortion constants have been determined and reported for most molecules in the document. Where possible, comparisons have been made amongst groups of similar molecules to try and get insight into the nature of the bonds those molecules are forming. This has been achieved the the comparisons of nuclear electric quadrupole and nuclear magnetic coupling constants, and the results therein have been determined and reported.
3

Molecular basis of estrogen receptor antagonism /

Heldring, Nina, January 2006 (has links)
Diss. (sammanfattning) Stockholm : Karol. inst., 2006. / Härtill 4 uppsatser.
4

Determinação de estruturas cristalinas por difração de raios-x: aplicação a um complexo de lantanídeo e a um composto orgânico natural / X-ray crystal structures of a lanthanide complex and a natural organic compound

Miranda, Jussara Marques de 12 May 1986 (has links)
O primeiro capítulo desta dissertação é dedicado a uma revisão teórica da interação dos raios-X com cristais e métodos utilizados para a determinação de estruturas cristalinas. Nos capítulos seguintes, descreve-se os equipamentos experimentais utilizados e resolução de duas estruturas cristalinas cujos principais resultados são apresentados a seguir: Estrutura do complexo HO(ReO4)34 TDTD 3 H2O. Sistema cristalino; monoclínico; grupo espacial P21/c; a=17.955(3) Å b=17.100(6) Å c=12.570(3) Å &#946=92.48(2) ° V=3855(3) ޵ z=4; Dc = 2.720 g/cm3; (MoK&#945)= 0.71073 Å &#181=114.08 cm-1. O índice de discordância final foi de R = 6.4% para 3050 reflexões com I >3&#963(I). O cátion HO+3 é coordenado por oito átomos de oxigênio, que configuram um dodecaedro (simetrias D2d). Os poliedros de coordenação são ligados por grupos TDTD, dando origem a cadeias infinitas na direção a. Estrutura de Ormosalin - C14H16O6. Sistema cristalino: monoclínico, grupo espacial: P21/c; a=10.765(4) Å b=14.692(5) Å c=8.374(4); &#946=98.02(3)° V=1305(2) &#1973, z=4, Dc = 1.43 g/cm3, &#955(MoK&#945)=0.71073 &#197, &#191=0.07 mm-1; R=0.058 para 807 reflexões com estrutura conta com dois anéis de cinco membros em conformação torcida antissimétrica / In the first chapter of this work we review some theoretical aspects concerning the interaction of X-rays with crystals and the methods used to determine crystal structure. The following chapters describe the experimental equipments used and the determination of two crystalline structures. The main results obtained are now out11ned. The structure of the complex HO(ReO4)34 TDTD 3 H2O. Crystal system, monoclinic, space P21/c; a=17.955(3) Å b=17.100(6) Å c=12.570(3) Å &#946=92.48(2) ° V=3855(3) ޵ z=4; Dc = 2.720 g/cm3; (MoK&#945)= 0.71073 Å &#181=114.08 cm-1. The final R factor was 6.4 % for 3050 ref1eetions with I&#88053&#963(I). The cation HO+3 is coordinated by eight oxygen atoms which have a dodecahedron configuration (symme - try D2d). The coordination polyhedrons are linked together by a TDTD group that coordinates two neighbouring cations HO+3, giving rise to an infinite chain along the crystallographic a direction. The structure of Orrnosalin C14H16O6. Crystal system, monoclinic; space group P21/c; a=10.765(4) Å b=14.692(5) Å c=8.374(4); &#946=98.02(3)° V=1305(2) &#1973, z=4, Dc = 1.43 g/cm3, &#955(MoK&#945)=0.71073 &#197, &#191=0.07 mm-1; R=0.058 for 807 reflections with I&#88053&#963(I). The structure consists of two five membered rings forming a anti - symmetric twisted conformation
5

Characterization of anthocyanidin-accumulating Lc-alfalfa for ruminants: nutritional profiles, digestibility, availability and molecular structures, and bloat characteristics

Jonker, Arjan 07 June 2011
Grazing cattle on alfalfa (Medicago sativa L.) would be economically beneficial, but its rapid initial rate of protein degradation results in pasture bloat, low efficiency of protein utilization and excessive N pollution into the environment. Introducing a gene that stimulates the accumulation of mono/polymeric anthocyanidins might reduce the ruminal protein degradation rate and reduce bloat related foam stability. The overall objective of this thesis was to evaluate newly developed anthocyanidin-accumulating Lc-alfalfa progeny for nutritional properties (composition, site of degradation and molecular structure), environmental emissions and bloat characteristics. The objective of the first study was to determine survival and phytochemical and chemical profiles of Lc-alfalfa progeny (BeavLc1, RambLc3 and RangLc4) and their non-transgenic (NT) parental cultivars (Beaver, Rambler and Rangelander). Lc-alfalfa forage accumulated enhanced amounts of anthocyanidin, with an average concentration of 197.4 µg/g DM, while proanthocyanidin (i.e. condensed tannins) were not detected. Both of these metabolites were absent in the NT-parental varieties. Lc-alfalfa progeny had ~3 % less crude protein (CP) and ~3 % more carbohydrates (CHO), which resulted in their 11 g/kg lower N:CHO ratio compared with NT-alfalfa. Total rumen-degradable N:CHO ratio based on chemical analysis was 12.9 g/kg lower in Lc-alfalfa compared with NT-alfalfa. The objective of the second study was to evaluate in vitro degradation, fermentation and microbial-N partitioning of three forage color phenotypes [green, light purple-green (LPG) and purple-green (PG)] within Lc-progeny and their parental green NT-alfalfa varieties. Purple-green-Lc alfalfa accumulated more anthocyanidin than Green-Lc with LPG-Lc intermediate. Gas, methane and ammonia accumulation rates were slower for the two purple-Lc phenotypes compared with NT-alfalfa with Green-Lc intermediate. Effective degradable DM and N were lower in the three Lc-phenotypes compared with NT-alfalfa. Anthocyanidin concentration correlated negatively with gas and methane production rates and effective degradability of DM and N. The objectives of the third study were to evaluate in situ ruminal degradation characteristics and synchronization ratios, and to model protein availability to dairy cattle and net energy for lactation of three Lc-alfalfa progenies, BeavLc1, RambLc3 and RangLc4 and the cultivar AC Grazeland (selected for a low initial rate of ruminal degradation). Anthocyanidin accumulation was on average 163.4 ìg/g DM in the three Lc-progeny while AC Grazeland did not accumulate anthocyanidin. The basic chemical composition of the original samples, soluble and potentially degradable fractions and degradation characteristics of crude protein and carbohydrates were similar in Lc-alfalfa and AC Grazeland. The undegradable in situ crude protein and neutral detergent fiber fraction were, respectively, 1.3 %CP and 4.8 %CHO lower in the three Lc-progeny compared with AC Grazeland. Lc-alfalfa had a 0.34 MJ/kg DM higher net energy for lactation and tended to have a 11.9, 6.9 and 8.4 g/kg DM higher rumen degradable protein, rumen degraded protein balance and intestinal available protein, respectively, compared with AC Grazeland,. The hourly rumen degraded protein balance included an initial and substantial peak (over-supply) of protein relative to energy which was highest in RangLc4 and lowest in RambLc3. The hourly rumen degraded protein balance between 4 and 24 h was similar and more balanced for all four alfalfa populations. The objective of the fourth study was to determine foam formation and stability in vitro from aqueous leaf extracts of three Lc-alfalfa progeny (BeavLc1, RambLc3, RangLc4), parental NT-alfalfa and AC Grazeland (bloat reduced cultivar) harvested in the field at 07:00 or 18:00 h. Anthocyanidin accumulation averaged 247.5 ìg/g DM in the leaves of the three Lc-progeny. There was an interaction between population and harvest time for the foam parameters. Initial foam volume (0 min) and final foam volume (150 min) at 07:00 h were lower for AC Grazeland compared with all other treatments and lower for RangLc4 compared with the other two Lc-progeny at 0 min and NT-alfalfa at 150 min; while from the 18:00 h harvest, initial foam volume was larger for NT-alfalfa and final foam volume was larger for RambLc3 compared with AC Grazeland, BeavLc1 and RangLc4. Foam formation correlated positively (R = 0.30 to 0.44) with leaf DM content, leaf extract protein and ethanol-film content, spectroscopic vibration intensity due to all carbohydrates (CHOVI) and amide I:amide II ratio and negatively (R = -0.33 and -0.34; P<0.05) with á-helix:â-sheet ratio and amide I:CHOVI. Final foam volume correlated negatively (R = -0.53 to -0.25; P<0.05) with leaf extract pH, spectroscopic vibration intensity due to all protein structures, structural carbohydrates (SCVI) and lipids (CH2 and CH3 asymmetric stretching) and amide I:CHOVI ratio and corelated positively (R = 0.39 to 0.44; P<0.05) with CHOVI, amideI:SCVI ratio and CHOVI:SCVI ratio. In conclusion, all Lc-alfalfa progeny and phenotypes accumulated anthocyanidin in their forage. Lc-alfalfa progeny had lower protein and higher carbohydrate content which improved the nitrogen to carbohydrate balance compared to their parental NT-alfalfa cultivars. Rate of fermentation and effective degradability in vitro reduced for both purple anthocyanidin-accumulating Lc-alfalfa phenotypes compared with NT-alfalfa. Intestinal protein availability tended to be higher and net energy for lactation was higher from Lc-alfalfa progeny for dairy cattle compared with AC Grazeland. Foaming properties were reduced in Lc-alfalfa progeny compared with parental non-transgenic alfalfa but not compared with AC Grazeland. However, differences between the Lc-alfalfa progeny and other cultivars were small. Therefore, further increases in mono/polymeric anthocyanidin accumulation in alfalfa are required in order to develop an alfalfa cultivar with superior nutritional and bloat preventing characteristics compared to currently available alfalfa cultivars.
6

Characterization of anthocyanidin-accumulating Lc-alfalfa for ruminants: nutritional profiles, digestibility, availability and molecular structures, and bloat characteristics

Jonker, Arjan 07 June 2011 (has links)
Grazing cattle on alfalfa (Medicago sativa L.) would be economically beneficial, but its rapid initial rate of protein degradation results in pasture bloat, low efficiency of protein utilization and excessive N pollution into the environment. Introducing a gene that stimulates the accumulation of mono/polymeric anthocyanidins might reduce the ruminal protein degradation rate and reduce bloat related foam stability. The overall objective of this thesis was to evaluate newly developed anthocyanidin-accumulating Lc-alfalfa progeny for nutritional properties (composition, site of degradation and molecular structure), environmental emissions and bloat characteristics. The objective of the first study was to determine survival and phytochemical and chemical profiles of Lc-alfalfa progeny (BeavLc1, RambLc3 and RangLc4) and their non-transgenic (NT) parental cultivars (Beaver, Rambler and Rangelander). Lc-alfalfa forage accumulated enhanced amounts of anthocyanidin, with an average concentration of 197.4 µg/g DM, while proanthocyanidin (i.e. condensed tannins) were not detected. Both of these metabolites were absent in the NT-parental varieties. Lc-alfalfa progeny had ~3 % less crude protein (CP) and ~3 % more carbohydrates (CHO), which resulted in their 11 g/kg lower N:CHO ratio compared with NT-alfalfa. Total rumen-degradable N:CHO ratio based on chemical analysis was 12.9 g/kg lower in Lc-alfalfa compared with NT-alfalfa. The objective of the second study was to evaluate in vitro degradation, fermentation and microbial-N partitioning of three forage color phenotypes [green, light purple-green (LPG) and purple-green (PG)] within Lc-progeny and their parental green NT-alfalfa varieties. Purple-green-Lc alfalfa accumulated more anthocyanidin than Green-Lc with LPG-Lc intermediate. Gas, methane and ammonia accumulation rates were slower for the two purple-Lc phenotypes compared with NT-alfalfa with Green-Lc intermediate. Effective degradable DM and N were lower in the three Lc-phenotypes compared with NT-alfalfa. Anthocyanidin concentration correlated negatively with gas and methane production rates and effective degradability of DM and N. The objectives of the third study were to evaluate in situ ruminal degradation characteristics and synchronization ratios, and to model protein availability to dairy cattle and net energy for lactation of three Lc-alfalfa progenies, BeavLc1, RambLc3 and RangLc4 and the cultivar AC Grazeland (selected for a low initial rate of ruminal degradation). Anthocyanidin accumulation was on average 163.4 ìg/g DM in the three Lc-progeny while AC Grazeland did not accumulate anthocyanidin. The basic chemical composition of the original samples, soluble and potentially degradable fractions and degradation characteristics of crude protein and carbohydrates were similar in Lc-alfalfa and AC Grazeland. The undegradable in situ crude protein and neutral detergent fiber fraction were, respectively, 1.3 %CP and 4.8 %CHO lower in the three Lc-progeny compared with AC Grazeland. Lc-alfalfa had a 0.34 MJ/kg DM higher net energy for lactation and tended to have a 11.9, 6.9 and 8.4 g/kg DM higher rumen degradable protein, rumen degraded protein balance and intestinal available protein, respectively, compared with AC Grazeland,. The hourly rumen degraded protein balance included an initial and substantial peak (over-supply) of protein relative to energy which was highest in RangLc4 and lowest in RambLc3. The hourly rumen degraded protein balance between 4 and 24 h was similar and more balanced for all four alfalfa populations. The objective of the fourth study was to determine foam formation and stability in vitro from aqueous leaf extracts of three Lc-alfalfa progeny (BeavLc1, RambLc3, RangLc4), parental NT-alfalfa and AC Grazeland (bloat reduced cultivar) harvested in the field at 07:00 or 18:00 h. Anthocyanidin accumulation averaged 247.5 ìg/g DM in the leaves of the three Lc-progeny. There was an interaction between population and harvest time for the foam parameters. Initial foam volume (0 min) and final foam volume (150 min) at 07:00 h were lower for AC Grazeland compared with all other treatments and lower for RangLc4 compared with the other two Lc-progeny at 0 min and NT-alfalfa at 150 min; while from the 18:00 h harvest, initial foam volume was larger for NT-alfalfa and final foam volume was larger for RambLc3 compared with AC Grazeland, BeavLc1 and RangLc4. Foam formation correlated positively (R = 0.30 to 0.44) with leaf DM content, leaf extract protein and ethanol-film content, spectroscopic vibration intensity due to all carbohydrates (CHOVI) and amide I:amide II ratio and negatively (R = -0.33 and -0.34; P<0.05) with á-helix:â-sheet ratio and amide I:CHOVI. Final foam volume correlated negatively (R = -0.53 to -0.25; P<0.05) with leaf extract pH, spectroscopic vibration intensity due to all protein structures, structural carbohydrates (SCVI) and lipids (CH2 and CH3 asymmetric stretching) and amide I:CHOVI ratio and corelated positively (R = 0.39 to 0.44; P<0.05) with CHOVI, amideI:SCVI ratio and CHOVI:SCVI ratio. In conclusion, all Lc-alfalfa progeny and phenotypes accumulated anthocyanidin in their forage. Lc-alfalfa progeny had lower protein and higher carbohydrate content which improved the nitrogen to carbohydrate balance compared to their parental NT-alfalfa cultivars. Rate of fermentation and effective degradability in vitro reduced for both purple anthocyanidin-accumulating Lc-alfalfa phenotypes compared with NT-alfalfa. Intestinal protein availability tended to be higher and net energy for lactation was higher from Lc-alfalfa progeny for dairy cattle compared with AC Grazeland. Foaming properties were reduced in Lc-alfalfa progeny compared with parental non-transgenic alfalfa but not compared with AC Grazeland. However, differences between the Lc-alfalfa progeny and other cultivars were small. Therefore, further increases in mono/polymeric anthocyanidin accumulation in alfalfa are required in order to develop an alfalfa cultivar with superior nutritional and bloat preventing characteristics compared to currently available alfalfa cultivars.
7

Determinação de estruturas cristalinas por difração de raios-x: aplicação a um complexo de lantanídeo e a um composto orgânico natural / X-ray crystal structures of a lanthanide complex and a natural organic compound

Jussara Marques de Miranda 12 May 1986 (has links)
O primeiro capítulo desta dissertação é dedicado a uma revisão teórica da interação dos raios-X com cristais e métodos utilizados para a determinação de estruturas cristalinas. Nos capítulos seguintes, descreve-se os equipamentos experimentais utilizados e resolução de duas estruturas cristalinas cujos principais resultados são apresentados a seguir: Estrutura do complexo HO(ReO4)34 TDTD 3 H2O. Sistema cristalino; monoclínico; grupo espacial P21/c; a=17.955(3) &#197; b=17.100(6) &#197; c=12.570(3) &#197; &#946=92.48(2) &#176; V=3855(3) &#1973; z=4; Dc = 2.720 g/cm3; (MoK&#945)= 0.71073 &#197; &#181=114.08 cm-1. O índice de discordância final foi de R = 6.4% para 3050 reflexões com I >3&#963(I). O cátion HO+3 é coordenado por oito átomos de oxigênio, que configuram um dodecaedro (simetrias D2d). Os poliedros de coordenação são ligados por grupos TDTD, dando origem a cadeias infinitas na direção a. Estrutura de Ormosalin - C14H16O6. Sistema cristalino: monoclínico, grupo espacial: P21/c; a=10.765(4) &#197; b=14.692(5) &#197; c=8.374(4); &#946=98.02(3)&#176; V=1305(2) &#1973, z=4, Dc = 1.43 g/cm3, &#955(MoK&#945)=0.71073 &#197, &#191=0.07 mm-1; R=0.058 para 807 reflexões com estrutura conta com dois anéis de cinco membros em conformação torcida antissimétrica / In the first chapter of this work we review some theoretical aspects concerning the interaction of X-rays with crystals and the methods used to determine crystal structure. The following chapters describe the experimental equipments used and the determination of two crystalline structures. The main results obtained are now out11ned. The structure of the complex HO(ReO4)34 TDTD 3 H2O. Crystal system, monoclinic, space P21/c; a=17.955(3) &#197; b=17.100(6) &#197; c=12.570(3) &#197; &#946=92.48(2) &#176; V=3855(3) &#1973; z=4; Dc = 2.720 g/cm3; (MoK&#945)= 0.71073 &#197; &#181=114.08 cm-1. The final R factor was 6.4 % for 3050 ref1eetions with I&#88053&#963(I). The cation HO+3 is coordinated by eight oxygen atoms which have a dodecahedron configuration (symme - try D2d). The coordination polyhedrons are linked together by a TDTD group that coordinates two neighbouring cations HO+3, giving rise to an infinite chain along the crystallographic a direction. The structure of Orrnosalin C14H16O6. Crystal system, monoclinic; space group P21/c; a=10.765(4) &#197; b=14.692(5) &#197; c=8.374(4); &#946=98.02(3)&#176; V=1305(2) &#1973, z=4, Dc = 1.43 g/cm3, &#955(MoK&#945)=0.71073 &#197, &#191=0.07 mm-1; R=0.058 for 807 reflections with I&#88053&#963(I). The structure consists of two five membered rings forming a anti - symmetric twisted conformation
8

Synthetic, High Field NMR Spectroscopic And Structural Studies On (Triphenylphosphazenyl) Cyclotriphosphazenes And Bicyclic Phosphazenes

Narasimhamurthy, S 12 1900 (has links) (PDF)
No description available.
9

Μελέτη του περιβάλλοντος αλκαλικών ιόντων και υαλοσχηματιστών με προηγμένες τεχνικές NMR και κβαντομηχανικοί υπολογισμοί

Αγγελοπούλου, Αθηνά 15 January 2009 (has links)
Συστηματική μελέτη πυριτικών, πυριτίου-ασβεστίου και φωσφοπυριτικών γυαλιών, με σύσταση 80 SiO2 - (20-x) Na2O - x Me2O (όπου x=0, 10 και Me=Li ή K), 48.7SiO2 - 26.9CaO - (24.4-x) Na2O - x Me2O (όπου x=0, 12.2 και Me=Li ή K) και 46.1 SiO2 - 2.6 P2O5 - 26.9 CaO - (24.4-x) Na2O - x Me2O (όπου x=0, 12.2 και Me=Li ή K), γίνεται με φασματοσκοπικές τεχνικές πυρηνικού μαγνητικού συντονισμού MAS NMR (Magic Angle Spinning Nuclear Magnetic Resonance) και MQ–MAS NMR (Multiple Quantum-MAS NMR). Η 29Si MAS NMR ανάλυση του Na2O πυριτικού γυαλιού έδειξε την ύπαρξη δύο κορυφών, οι οποίες αποδίδονται σε Q3 και Q4 πυριτικές δομές. Η υποκατάσταση Na από Κ διατηρεί τις Q3 και Q4 δομές ενώ στο Na2O-Li2O γυαλί, παρατηρήθηκαν τρεις κορυφές, οι οποίες αποδίδονται σε Q3, Q4-3 και Q4-4 πυριτικές δομές. H Q4-4 είναι σχετικά στενή και υποδηλώνει έναρξη κρυστάλλωσης του δικτύου λόγω της μικρής έντασης του σήματος. Στο γυαλί Na2O πυριτίου-ασβεστίου, η ανάλυση οδήγησε σε δυο κορυφές οι οποίες αποδίδονται σε Q1 και Q2 δομές, ενώ στο Na2O-K2O γυαλί, το φάσμα αναλύθηκε μόνο μια κορυφή που αντιπροσωπεύει Q2 πυριτικές δομές. Από την άλλη, στο γυαλί Na2O-Li2O, παρατηρήθηκαν δύο κορυφές οι οποίες αντιστοιχούν σε Q2 και Q3 δομές. Στο Na2O φωσφοπυριτικό γυαλί, η ανάλυση οδήγησε στις κορυφές που αποδίδονται σε Q2 και Q3 δομές. Η 23Na MQ-MAS NMR ανάλυση στο Na2O πυριτικό γυαλί οδήγησε στην παρουσία δύο ιοντικών περιοχών νατρίου (site 1: δiso= 5.1 ppm, CQ= 0.96 MHz, ΔCS= 20 ppm και site 2: δiso= 1.9 ppm, CQ= 3.06 MHz, ΔCS= 20 ppm). Η υποκατάσταση Na από Li ή Κ διατηρεί τις δύο ιοντικές περιοχές στα γυαλιά. Στο γυαλί Na2O πυριτίου-ασβεστίου, η ανάλυση οδήγησε μόνο σε μια ιοντική περιοχή η οποία είναι η site 2 (δiso= 5.4 ppm, CQ= 2.83 MHz, ΔCS= 17 ppm). Στα υπόλοιπα γυαλιά δεν παρατηρούνται διαφορές κατά την υποκατάσταση Na από Li ή Κ. Στο 24.4 Na2O φωσφοπυριτικό γυαλί παρατηρήθηκαν τρεις ιοντικές περιοχές (site 1: δiso= 6.0 ppm, CQ= 1.4 MHz, ΔCS= 20 ppm, site 2: δiso= 6.8 ppm, CQ= 2.6 MHz, ΔCS= 20 ppm, και site 3: δiso= 6.6 ppm, CQ= 1.2 MHz, ΔCS= 1 ppm). Η υποκατάσταση Na από Li ή Κ οδήγησε στην απουσία της τρίτης και πιο ισχυρής ιοντικής περιοχής (site 3). Πιθανολογούμε ότι η απουσία της σχετίζεται με την τροποποίηση του δικτύου που προέρχεται από την εισαγωγή του φωσφόρου στο υαλώδες δίκτυο. Η μελέτη μας επεκτάθηκε και στην μοριακή προσομοίωση των γυαλιών των τριών οικογενειών με την βοήθεια του προγράμματος Gaussian 03W. Πρώτα έγινε η γεωμετρική προσομοίωση του πλέγματος και μετά η προσομοίωση των NMR παραμέτρων με την χρήση της DFT μεθόδου (Density Functional Theory) και με τις βάσεις 6-311++G, 6-31G και 3-21++G. Οι δομές που προέκυψαν έδωσαν μια εικόνα του πυριτικού, πυριτίου-ασβεστίου και φωσφοπυριτικού υαλώδους δικτύου. Οι δομές των αλκαλίων αποτελούνται από τετραεδρικής, εξαεδρικής και οκταεδρικής συμμετρίας κυψελίδες. Μετά από υπολογισμούς διαφόρων πιθανών δομών καταλήξαμε στις δομές για την ερμηνεία των φασμάτων σε εκείνες που υπάρχει καλή συμφωνία μεταξύ των θεωρητικών και πειραματικών 23Na NMR αποτελεσμάτων. Συγκεκριμένα, η site 2 προέρχεται από ένα 23Na σε XXX-εδρικό περιβάλλον. Η site 3 μπορεί να προέρχεται από οκταεδρικούς σχηματισμούς υψηλής συμμετρίας των ιόντων Na γιατί αυτές οι περιοχές οδηγούν με βάση τους υπολογισμούς μας σε περιβάλλον με αυξημένη ιοντική ισχύ και συμμετρία. / Silicate, calcium-silicate and phosphosilicate glasses of the composition 80 SiO2 - (20-x) Na2O - x Me2O (where x=0, 10 and Me=Li or K), 48.7SiO2 - 26.9CaO - (24.4-x) Na2O - xMe2O (where x=0, 12.2 and Me=Li or K) and 46.1 SiO2 - 2.6 P2O5 - 26.9 CaO - (24.4-x) Na2O - x Me2O (where x=0, 12.2 and Me=Li or K), have been investigated using the advanced NMR methods of MAS NMR (Magic Angle Spinning Nuclear Magnetic Resonance) and MQ-MAS NMR (Multiple Quantum-MAS NMR). The 29Si MAS NMR analysis of the sodium silicate glass revealed two lines attributed to Q3 and Q4 silicate species. Substitution of Na with K conserves the Q3 and Q4 species while in the Na2O-Li2O glass, three lines were obtained attributed to Q3, Q4-3 and Q4-4 species. The Q4-4 signal is attributed to initial stage of crystallization due to the narrow size distribution and low intensity. In the sodium calcium-silicate glass, two lines were resolved assigned to Q1 and Q2, while in the Na2O-K2O glass, only one line was resolved attributed to Q2 species. For the Na2O-Li2O glass, two lines were revealed assigned to Q2 and Q3. In the sodium phosphosilicate glass, the analysis revealed two lines ascribed to Q2 and Q3. The 23Na MQ-MAS NMR analysis in the sodium silicate glass exhibits two Na ionic sites (site 1: δiso= 5.1 ppm, CQ= 0.96 MHz, ΔCS= 20 ppm and site 2: δiso= 1.9 ppm, CQ= 3.06 MHz, ΔCS= 20 ppm). Substitution of Na with Li or K conserves the two sites in the glasses. For the sodium calcium-silicate glass, the analysis revealed only one site (site 2: δiso= 5.4 ppm, CQ= 2.83 MHz, ΔCS= 17 ppm). No difference was observed by the substitution of Na with Li or K in the glasses. In the 24.4 Na2O phosphosilicate glass three sites were obtained with: site 1 (δiso= 6.0 ppm, CQ= 1.4 MHz, ΔCS= 20 ppm), site 2 (δiso= 6.8 ppm, CQ= 2.6 MHz, ΔCS= 20 ppm), site 3 (δiso= 6.6 ppm, CQ= 1.2 MHz, ΔCS= 1 ppm). The substitution of Na with Li or K resulted in the absence of the third and most ionic site, which is probably associated with the presence of phosphorus in the glassy network. Our study was completed by the molecular simulation of the three types of glasses, for which the Gaussian 03W program was used. For the geometrical optimization and the optimization of the NMR parameters was used the DFT (Density Functional Theory) method and the 6-311++G, 6-31G, and 3-21++G basis sets. The resulting structures gave an insight into the silicate, calcium-silicate and phosphosilicate glassy network. These structures consist of tetrahedral, hexahedral, and octahedral symmetry shells which enclose the alkali ions. The good agreement between the theoretical and experimental 23Na NMR results leads to the depiction of the Na ionic sites and especially of site 2. This site was attributed to sodium in XXX-coordination. Concerning site 3, was observed that the increased ionic strength of the site could possible be ascribed to high symmetry octahedral configurations of Na ions.
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Improvements in nutritive value of canola meal with pelleting

2015 February 1900 (has links)
Production of and demand for Canadian canola meal have been increased yearly. In order to improve the competitiveness of canola meal domestically and internationally, as well as to develop potential markets for canola meal, it is necessary to develop canola meal-based products that have high feed values and can be easily transported. The objectives of this research were: 1) to investigate the effects of temperature and time of conditioning during pelleting process on the nutritive values of canola meal in terms of chemical profiles, protein and carbohydrate subfractions, and energy values, using the AOAC procedures, CNCPS v6.1 and NRC (2001), respectively; 2) to detect the effects of temperature and time of conditioning during the pelleting process on rumen degradation and intestinal digestion characteristics and predicted protein supply of canola meal, using the in situ procedure, the three-step in vitro procedure, and the NRC 2001 model; and 3) to determine pelleting-induced changes in spectral characteristics of molecular structures of canola meal using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) with univariate and multivariate analysis, and reveal the relationship between molecular structures of protein and carbohydrate and nutrient values, rumen degradation and intestinal digestion characteristics, and predicted protein supply of canola meal. Three different conditioning temperatures (70, 80 and 90ºC) and two different conditioning time (50 and 75 sec) were applied in this research. Two different batches of canola meal from a commercial feed company were selected. A randomized complete block design (RCBD) with 3 × 2 factorial arrangement was employed in this research. Molecular spectral functional groups related to protein, cellulosic compounds, and carbohydrates were used in the spectral study. This research indicated: 1) soluble crude protein (SCP) was decreased and neutral detergent insoluble CP (NDICP) was increased with increasing temperature; 2) the lowest protein rumen degradation of pellets was observed at conditioning temperature of 90 ºC and protein rumen degradation was increased by pelleting; 3) the amount of protein digested in the small intestine tended to increase with increasing conditioning temperature; 4) pelleting under different temperatures and time in the current study shifted the protein digestion site to the rumen, rather than to the small intestine; 5) with respect to predicted protein supply, based on the NRC 2001 model, increasing conditioning temperature tended to increase the metabolizable protein supply of canola meal pellets to dairy cattle; 6) changes in the molecular structure of canola meal induced by pelleting can be detected by ATR-FTIR; 7) not only protein molecular structure characteristics but also carbohydrate molecular structure characteristics play important roles in determining nutrient values, rumen degradation and intestinal digestion characteristics, and the predicted protein supply of canola meal.

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