Boron influence on concentration of polyols and other sugars in Eucalyptus

Although the functions of the element Boron (B) in plants have not been sufficiently clarified, several hypotheses have been raised. Some of the functions attributed to this element are synthesis and transport of carbohydrates. To evaluate the effect of B on the synthesis of some polyols and sugars in Eucalyptus grandis and hybrids "urograndis", these species were submitted to situations of supply and restriction of B. The experiment was carried out in a greenhouse, arranged in a randomized block design in a 2 x 2 factorial scheme, with 5 replicates of each genotype. The B levels were provided in the form of nutrient solution. No significant difference was observed in the content of mannitol, sorbitol, myo-inositol and scyllo-inositol and sugars α-glucose and β-glucose between E. grandis and hybrids. Arabinose was the only one to present a higher content in E. grandis on restriction of B. The effect of the presence of B was very expressive, but regarding B supply, the plants showed significant increase in the synthesis of the compounds evaluated.

Application of isotope-selective non-dispersive infrared spectrometry for the evaluation of the 13C-urea breath test: comparison with three concordant methods

The aim of this work was to compare the performance of isotope-selective non-dispersive infrared spectrometry (IRIS) for the 13C-urea breath test with the combination of the 14C-urea breath test (14C-UBT), urease test and histologic examination for the diagnosis of H. pylori (HP) infection. Fifty-three duodenal ulcer patients were studied. All patients were submitted to gastroscopy to detect HP by the urease test, histologic examination and 14C-UBT. To be included in the study the results of the 3 tests had to be concordant. Within one month after admission to the study the patients were submitted to IRIS with breath samples collected before and 30 min after the ingestion of 75 mg 13C-urea dissolved in 200 ml of orange juice. The samples were mailed and analyzed 11.5 (4-21) days after collection. Data were analyzed statistically by the chi-square and Mann-Whitney test and by the Spearman correlation coefficient. Twenty-six patients were HP positive and 27 negative. There was 100% agreement between the IRIS results and the HP status determined by the other three methods. Using a cutoff value of delta-over-baseline (DOB) above 4.0 the IRIS showed a mean value of 19.38 (minimum = 4.2, maximum = 41.3, SD = 10.9) for HP-positive patients and a mean value of 0.88 (minimum = 0.10, maximum = 2.5, SD = 0.71) for negative patients. Using a cutoff value corresponding to 0.800% CO2/weight (kg), the 14C-UBT showed a mean value of 2.78 (minimum = 0.89, maximum = 5.22, SD = 1.18) in HP-positive patients. HP-negative patients showed a mean value of 0.37 (minimum = 0.13, maximum = 0.77, SD = 0.17). IRIS is a low-cost, easy to manage, highly sensitive and specific test for H. pylori detection. Storing and mailing the samples did not interfere with the performance of the test.

Isotope analysis (δ13C) of pulpy whole apple juice

The objectives of this study were to develop the method of isotope analysis to quantify the carbon of C3 photosynthetic cycle in pulpy whole apple juice and to measure the legal limits based on Brazilian legislation in order to identify the beverages that do not conform to the Ministry of Agriculture, Livestock and Food Supply (MAPA). This beverage was produced in a laboratory according to the Brazilian law. Pulpy juices adulterated by the addition of sugarcane were also produced. The isotope analyses measured the relative isotope enrichment of the juices, their pulpy fractions (internal standard) and purified sugar. From those results, the quantity of C3 source was estimated by means of the isotope dilution equation. To determine the existence of adulteration in commercial juices, it was necessary to create a legal limit according to the Brazilian law. Three brands of commercial juices were analyzed. One was classified as adulterated. The legal limit enabled to clearly identify the juice that was not in conformity with the Brazilian law. The methodology developed proved efficient for quantifying the carbon of C3 origin in commercial pulpy apple juices.

Carbon isotope analysis in apple nectar beverages

The aims of this study were to use the isotope analysis method to quantify the carbon of C3 photosynthetic cycle in commercial apple nectars and to determine the legal limit to identify the beverages that do not conform to the safety standards established by the Brazilian Ministry of Agriculture, Livestock and Food Supply. These beverages (apple nectars) were produced in the laboratory according to the Brazilian legislation. Adulterated nectars were also produced with an amount of pulp juice below the permitted threshold limit value. The δ13C values of the apple nectars and their fractions (pulp and purified sugar) were measured to quantify the C3 source percentage. In order to demonstrate the existence of adulteration, the values found were compared to the limit values established by the Brazilian Law. All commercial apple nectars analyzed were within the legal limits, which enabled to identify the nectars that were in conformity with the Brazilian Law. The isotopic methodology developed proved efficient to quantify the carbon of C3 origin in commercial apple nectars.

Histoire du Saint-Graal, et Histoire de Merlin, par ROBERT DE BORON.

Contient : Histoire du Saint-Graal, par ROBERT DE BORON. « [C]hil ki se tient et juge au plus peceor de tous, mande salus... » [Le Saint Graal, éd. Hucher, II, 3, note] ; « ... et commenche messire ROBERS en tel manière [Ibid., III, 303], comme vos poerés oïr, s'il est ki le vos die. Or nous consaut Sainte Marie. Explicit li commencemens de l'estoire del s. Graal, et chi après vient l'estoire de Merlin. Dieu nous maint tous à boine fin. Amen. » [Cf. l'explicit dans le ms. franç. 95] ; Histoire de Merlin, par ROBERT DE BORON. « Mout fut iriés li anemis, quant nostre sires ot estei en enfer... » ; «... si come li contes le vous devisera cha avant. Explicit l'enserrement de Merlin. Diex nous maint tous à boine fin. Amen »

Investigations towards the synthesis of isotope labelled analogues of tocopherols and tocotrienols /

Vitamin E is considered as the most effective lipophilic chain breaking antioxidant. a-Tocopherol and its analogues have been studied thoroughly with regards to its biokinetics and bioavailabily. Deuterated tocopherols have been synthesized and utilized in such studies. Tocotrienols are arousing more and more interest because of their high efficiency as antioxidants. However, to date, there is no effective synthetic method reported for deuterated tocotrienols. This thesis is focused on the investigation of the synthetic methods of deuterated tocotrienols and their analogues: 5-trideuteromethyl-a-tocotrienol, 5- trideuteromethyl-p-tocotrienol, tocotrienol acetate, silyl tocotrienol ether, etc. Several synthetic procedures for the preparation of poly-deuterated tocopherols are known. Mainly the deuterium is introduced by use of labelled formaldehyde and deuterated hydrogen chloride under Lewis acid catalysis. However, these methods are not effective in tocotrienols due to exchange of protons for deuterium at other sites under the acidic conditions. We developed several different approaches to generate polydeuterated tocotrienols by using both morpholinomethylation followed by reduction with NaCNBDs as deuterated reducing reagents and transmetalation strategy. The 5-trideuteromethyl-a-tocotrienol was finally obtained in a satisfactory yield of 60%. In addition, this thesis also discussed the study of structural comparison and the chemical property difference of tocopherols and tocotrienols, which provides hints to explain the reactivity difference of them towards oxidation at the C3-C4 positions.Furthermore, the methodology of halogenation and dehydrohalogenation of tocotrienol was explored to prepare a hexaene tocotrienol derivative as a florescent reporter of tocopherol.

Synthesis of isotope-labelled methoxypyrazine compounds as internal standards and quantitative determination of aroma methoxypyrazines in water and wines by solid-phase extraction with isotope dilution-GC-MS /

An efficient way of synthesizing the deuterium labelled analogues of three methoxypyrazine compounds: 2-d3-methoxy-3-isopropylpyrazine, 2-d3-methoxy-3- isobutylpyrazine, and 2-d3-methoxy-3-secbutylpyrazine, has been developed. To confirm that the deuterium labels had been incorporated into the expected positions in the molecules synthesized, the relevant characterization by NMR, HRMS and GC/MS analysis was conducted. Another part of this work involved quantitative determination of methoxypyrazines in water and wines. Solid-phase extraction (SPE) proved to be a suitable means for the sample separation and concentration prior to GC/MS analysis.Such factors as the presence of ethanol, salt, and acid have been investigated which can influence the recovery by SPE for the pyrazines from the water matrix. Significantly, in this work comparatively simple fractional distillation was attempted to replace the conventional steam distillation for pre-concentrating a sample with a relatively large volume prior to SPE. Finally, a real wine sample spiked with the relevant isotope-labelled methoxypyrazines was quantitatively analyzed, revealing that the wine with 10 beetles per litre contained 138 ppt of 2-methoxy-3-isopropylpyrazine. Interestingly, we have also found that 2-methoxy-3-secbutylpyrazine exhibits an extremely low detection limit in GC/MS analysis compared with the detection limit of the other two methoxypyrazines: 2- methoxy-3-isopropylpyrazine and 2-methoxy-3-isobutylpyrazine.

Exchange reactions of organic halides and organo-silicon compounds with boron tribromide and boron triiodide

Reactions of the boron halides with organic halides and organo-silicon compounds have been investigated. The results show exchange of halogens between the BX3 (X = Br# 1) and the organic halidef exchange of the halogen of the C-X bond being proved. The rates of halogen exchange vary. Reaction of the heavier halides with organo-silicon compounds indicated that the silicon-carbon bonds ruptured in the absence of electronegative atom attached to the silicon. The presence of an electronegative atom (halogen or oxygen) attached to the silicon causes the bond between the silicon and the electronegative atom to be preferentially broken. Products of exchange reactions of the boron halides and the organic halides or the organo-silicon compounds were studied by use of 1H NMR and GC/MS. From these results some possible mechanisms for the exchange reactions are postulated, but further work is indicated to prove the real courses of the reactions

NMR studies of mixed tetrahaloborates and some related boron trihalide complexes /|nGary John Schrobilgen. -- 260 St. Catharines, Ont. : [s. n.],

Nuclear magnetic resonance spectroscopy has been used to study donor-acceptor complexes of boron trifluoride with several ureas, tetramethylthiourea, tetramethylselenourea, and tetramethylquanidine as well as adducts of tetramethyl- -urea with BF2Cl, BFC1 2 , and BC1 3 - A large number of mixed tetrahaloborate ions, including some of the ternary ones such as BF2CIBr-,have been obtained by ligand exchange reactions and studied by NMR techniques. The bonding in these ions is of the same inherent interest as the bonding in the isoelectronic tetrahalomethanes which have been the subject of many detailed studies and have been involved in a controversy concerning the existence of and the nature of "fluorine hyperconjugation" or C-F P1T- Pn bonding_ Ligand exchange reactions also gave rise to the difluoroboron cation, (TMU)20BF2+o The difluoroboron cation has been observed in solutions of TMU-BF3 , and has been proposed as a possible intermediate for fluorine exchange reactions in BF3 adducts.

Synthesis of nanoporous materials for preconcentration and determination of trace elements by ICP-AES ; Investigation and elimination of the memory effects of mercury, gold, silver and boron in ICP-AES

Nanoporous materials with large surface area and well-ordered pore structure have been synthesized. Thiol groups were grafted on the materials' surface to make heavy metal ion pre-concentration media. The adsorption properties ofthe materials were explored. Mercury, gold and silver can be strongly adsorbed by these materials, even in the presence of alkaline earth metal ion. Though the materials can adsorb other heavy metal ions such as lead and copper, they show differential adsorption ability when several ions are present in solution. The adsorption sequence is: mercury> == silver> copper » lead and cadmium. In the second part of this work, the memory effects of mercury, gold, silver and boron were investigated. The addition of 2% L-cysteine and 1% thiourea eliminates the problems of the three metal ions completely. The wash-out time for mercury dropped from more than 20 minutes to 18 seconds, and the wash-out time for gold decreased from more than 30 minutes to 49 seconds. The memory effect of boron can be reduced by the use of mannitol.

Nuclear magnetic resonance studies of boron trihalide complexes of 1,1-BIS (dimethylamino) ethylene and related bases

Boron tribalide complexes of 1,1-bis(dimethylamino)ethylene (DME) , t etramethylurea (TMU), tetramethylguanidine (TMG) , and pentamethylguanidine (PMG) and also mixed boron t r ihalide adducts of DME have been investigated by 1H and 19F NMR spectroscopy. Both nitrogen and the C-Q-H carbon of DME are possible donor a toms to boron trihal ides but complexation has been found to occur only at carbon of DME. The initial adduct acts as a Bronsted acid and gives up a proton to free DME in solut ion. A side reaction in the DME-BF, system gives rise to trace amounts of a complex aSSigned as (DME)2BF2+. (DME)2BF2+ is produced in much larger quantities in t he DME-BF3-BC13 and DME-BF,-BBr, systems by reaction of free DME with DME:BF2X (X = Cl, Br). Restricted r otation about the C-N bonds of TMUlBC13 and n1U:BBr3 has been observed at low temperatures. This complements previous work in this system and confirms oxygen donation of TMU to boron trihalides . Restricted rotation at low temperatures also has been observed in DMEboron trihalide systems

The mechanism of formation of the mixed boron trihalide adducts of trimenthylamine

Boron trihalide and mixed boron trihalide adducts of trimethylamine have been prepared, and characterized by proton and fluorine N.M.R. spectroscopy. The acceptor power of the boron trihalides was seen to increase in the order BF3 < BC13 < BBr3 < BI3, corroborating previous evidence. The mixed boron trihalides had intermediate Lewis acidities. Solution reactions between adducts and free boron trihalides rapidly led to the formation of mixed adducts when the free boron trihalide is a stronger Lewis acid than that in the adduct. A slower reaction is observed when the free BX3 is a weaker Lewis aoid than that complexed. The mechanism of halogen exchange leading to the mixed (CH3)3NBX3 adducts was investigated. 10B labelling experiments precluded B-N bond rupture as a possible mechanism in solution; results are discussed in terms of halogen-bridged intermediates. Pre-ionization may be important for some systems. At higher temperatures, during gas phase reactions,B-N coordinate bond rupture may be the initial step of reaction. Two mixed adduots, namely (CH3)3NBClBr2 and (CH3)3NBHOIBr were prepared and characterized by Mass Spectrometry

Analysis of the electronic structure, hyperfine structure, and volume isotope shifts in the low lying states of BA I and BA II

Relativistic multi-configuration Dirac Fock (MCDF) wavefunctions coupled to good angular momentum J have been calculated for low lying states of Ba I and Ba II. These wavefunctions are compared with semiempirical ones derived from experimental atomic energy levels. It is found that significantly better agreement is obtained when close configurations are included in the MCDF wavefunctions. Calculations of the electronic part of the field isotope shift lead to very good agreement with electronic factors derived from experimental data. Furthermore, the slopes of the lines in a King plot analysis of many of the optical lines are predicted accurately by these calculations. However, the MCDF wavefunctions seem not to be of sufficient accuracy to give agreement with the experimental magnetic dipole and electric quadrupole hyperfine structure constants.

Volume isotope shifts in low lying transitions of Au I

Electronic factors in the volume isotope shift have been calculated in an ab initio way with the relativistic Dirac-Fock method for a number of different optical single/and two-photon transitions in Au I. The agreement with a semi-empirical method is within 10% for the resonance transition. For this one and a few other transitions the effect of core excitation has been analyzed with the Multi-configuration Dirac-Fock method as well, and it was found to reduce the electronic factor in the order of 5 %.