Lemon oil to beta-cyclodextrin ratio effect on the inclusion efficiency of beta-cyclodextrin and the retention of oil volatiles in the complex

Microencapsulation of lemon oil was undertaken with beta-cyclodextrin using a precipitation method at the five lemon oil to beta-cyclodextrin ratios of 3:97, 6:94, 9:91, 12:88, and 15:85 (w/w) in order to determine the effect of the ratio of lemon oil to beta-cyclodextrin on the inclusion efficiency of beta-cyclodextrin for encapsulating oil volatiles. The retention of lemon oil volatiles reached a maximum at the lemon oil to beta-cyclodextrin ratio of 6:94; however, the maximum inclusion capacity of beta-cyclodextrin and a maximum powder recovery were achieved at the ratio of 12:88, in which the beta-cyclodextrin complex contained 9.68% (w/w) lemon oil. The profile and proportion of selected flavor compounds in the beta-cyclodextrin complex and the starting lemon oil were not significantly different.

Sedimentologic, petrographic, and sulfur isotope constraints on fine-grained pyrite formation at Mount Isa Mine and environs, Northwest Queensland, Australia

Fine-grained pyrite is the earliest generation of pyrite and the most abundant sulfide within the Urquhart Shale at Mount Isa, northwest Queensland. The pyrite is intimately interbanded with ore-grade Pb-Zn miner alization at the Mount Isa mine but is also abundant north and south of the mine at several stratigraphic horizons within the Urquhart Shale. Detailed sedimentologic, petrographic, and sulfur isotope studies of the Urquhart Shale, mostly north of the mine, reveal that the fine-grained pyrite (delta(34)S = -3.3 to +26.3 parts per thousand) formed by thermochemical sulfate reduction during diagenesis. The sulfate source was local sulfate evaporites, pseudo morphs of which are present throughout the Urquhart Shale (i.e., gypsum, anhydrite, and barite). Deep-burial diagenetic replacement of these evaporites resulted in sulfate-bearing ground waters which migrated parallel to bedding. Fine-grained pyrite formed where these fluids infiltrated and then interacted with carbon-rich laminated siltstones. Comparison of the sulfur isotope systematics of fine-grained pyrite and spatially associated base metal sulfides from the Mount Isa Pb-Zn and Cu orebodies indicates a common sulfur source of ultimately marine origin for all sulfide types. Different sulfur isotope ratio distributions for the various sulfides are the result of contrasting formation mechanisms and/or depositional conditions rather than differing sulfur sources. The sulfur isotope systematics of the base metal and associated iron sulfide generations are consistent with mineralization by reduced hydrothermal fluids, perhaps generated by bulk reduction of evaporite-sourced sulfate-bearing waters generated deeper in the Mount Isa Group, the sedimentary sequence which contains the Urquhart Shale. The available sulfur isotope data from the Mount Isa orebodies are consistent with either a chemically and thermally zoned, evolving Cu-Pb-Zn system, or discrete Cu and Pb-Zn mineralizing events linked by a common sulfur source.

Encapsulation of lemon oil by paste method using beta-cyclodextrin: Encapsulation efficiency and profile of oil volatiles

Microencapsulation of lemon oil was undertaken by kneading with beta-cyclodextrin, at a beta-cyclodextrin to lemon oil ratio of 88:12 (w/w). The resulting paste samples of the complex were vacuum- or spray-dried. Ten selected lemon oil flavor volatiles (alpha-pinene, sabinene, beta-pinene, beta-myrcene, limonene, gamma-terpinene, terpinolene, linalool, neral, and geranial) in the complex were analyzed periodically after 1, 2, 5, 10, 15, 20, and 30 min of kneading time. The results indicated that the levels of these volatiles were not significantly different (P > 0.05) irrespective of mixing time or type of the drying (vacuum- or spray-drying) used. An optimum mixing time was found to be 15 min, at which time the maximum encapsulation of lemon oil (97.7 mg/g of beta-cyclodextrin) was obtained in the complex powder.

Spin-orbit mixing and nephelauxetic effects in the electronic spectra of nickel(II)-encapsulating complexes involving nitrogen and sulfur donors

A study of spin-orbit mixing and nephelauxetic effects in the electronic spectra of nickel(II)-encapsulating complexes involving mixed nitrogen and sulfur donors is reported. As the number of sulfur donors is systematically varied through the series [Ni(N6-xSx)](2+) (x = 0-6), the spin-forbidden (3)A(2)g --> E-1(g) and (3)A(2g) --> (1)A(1g) transitions undergo a considerable reduction in energy whereas the spin-allowed transitions are relatively unchanged. The [Ni(diAMN(6)sar)](2+) and [Ni(AMN(5)Ssar)](2+) complexes exhibit an unusual band shape for the (3)A(2g) --> T-3(2g) transition which is shown to arise from spin-orbit mixing of the E spin-orbit levels associated with the E-1(g) and T-3(2g) states. A significant differential nephelauxetic effect also arises from the covalency differences between the t(2g) and e(g) orbitals with the result that no single set of Racah B and C interelectron repulsion parameters adequately fit the observed spectra. Using a differential covalency ligand-field model, the spectral transitions are successfully reproduced with three independent variables corresponding to 10Dq and the covalency parameters f(t) and f(e), associated with the t(2g) and e(g) orbitals, respectively. The small decrease in f(t) from unity is largely attributed to central-field covalency effects whereas the dramatic reduction in f(e) with increasing number of sulfur donors is a direct consequence of the increased metal-ligand covalency associated with the sulfur donors. Covalency differences between the t(2g) and e(g) orbitals also result in larger 10Dq values than those obtained simply from the energy of the (3)A(2g) --> T-3(2g) spin-allowed transition.

Quantification of sulfur and sulfur-containing compounds in wastewaters by means of a combination of liquid chromatographic methods

Low-micromolar concentrations of sulfite, thiosulfate and sulfide, present in synthetic wastewater or anaerobic digester effluent, were quantified by means of derivatization with monobromobimane, followed by HPLC separation with fluorescence detection. The concentration of elemental sulfur was determined, after its extraction with chloroform from the derivatized sample, by HPLC with UV detection. Recoveries of sulfide (both matrices), and of thiosulfate and sulfite (synthetic wastewater) were between 98 and 103%. The in-run RSDs on separate derivatizations were 13 and 19% for sulfite (two tests), between 1.5 and 6.6% for thiosulfate (two tests) and between 4.1 and 7.7% for sulfide (three tests). Response factors for derivatives of sulfide and thiosulfate, but not sulfite, were steady over a 13-month period during which 730 samples were analysed. Dithionate and tetrathionate did not seem to be detectable with this method. The distinctness of the elemental sulfur and the derivatizing-agent peaks was improved considerably by detecting elution at 297 instead of 263 nm. (C) 2002 Elsevier Science B.V. All rights reserved.

Improvements to peroxide oxidation methods for analysing sulfur in acid sulfate soils

Improvements to peroxide oxidation methods for analysing acid sulfate soils (ASS) are introduced. The soil solution ratio has been increased to 1 : 40, titrations are performed in suspension, and the duration of the peroxide digest stage is substantially shortened. For 9 acid sulfate soils, the peroxide oxidisable sulfur value obtained using the improved method was compared with the reduced inorganic sulfur result obtained using the chromium reducible sulfur method. Their regression was highly significant, the slope of the regression line was not significantly different (P = 0.05) from unity, and the intercept not significantly different from zero. A complete sulfur budget for the improved method showed there was no loss of sulfur as has been reported for earlier peroxide oxidation techniques. When soils were very finely ground, efficient oxidation of sulfides was achieved, despite the milder digestion conditions. Highly sulfidic and organic soils were shown to be the most difficult to analyse using either the improved method or the chromium method. No single analytical method can be universally applied to all ASS, rather a suite of methods is necessary for a thorough understanding of many ASS. The improved peroxide method, in combination with the chromium method and the 4 M HCl extraction, form a sound platform for informed decision making on the management of acid sulfate soils.

Herbicidal activity of volatiles from coriander, winter savory, cotton lavender, and thyme isolated by hydrodistillation and supercritical fluid extraction

The volatiles from Coriandrum sativum L., Satureja montana L., Santolina chamaecyparissus L., and Thymus vulgaris L. were isolated by hydrodistillation (essential oil) and supercritical fluid extraction (volatile oil). Their effect on seed germination and root and shoot growth of the surviving seedlings of four crops (Zea mays L., Triticum durum L., Pisum sativum L., and Lactuca sativa L.) and two weeds (Portulaca oleracea L. and Vicia sativa L.) was investigated and compared with those of two synthetic herbicides, Agrocide and Prowl. The volatile oils of thyme and cotton lavender seemed to be promising alternatives to the synthetic herbicides because they were the least injurious to the crop species. The essential oil of winter savory, on the other hand, affected both crop and weeds and can be appropriate for uncultivated fields.

Composition and antioxidant activity of thymus vulgaris volatiles: comparison between supercritical fluid extraction and hydrodistillation

Supercritical fluid extraction (SEE) of the volatile oil from Thymus vulgaris L. aerial flowering parts was performed under different conditions of pressure, temperature, mean particle size and CO2 flow rate and the correspondent yield and composition were compared with those of the essential oil isolated by hydrodistillation (HD). Both the oils were analyzed by GC and GC-MS and 52 components were identified. The main volatile components obtained were p-cymene (10.0-42.6% for SFE and 28.9-34.8% for HD), gamma-terpinene (0.8-6.9% for SFE and 5.1-7.0% for HD), linalool (2.3-5.3% for SFE and 2.8-3.1% for HD), thymol (19.5-40.8% for SFE and 35.4-41.6% for HD), and carvacrol (1.4-3.1% for SFE and 2.6-3.1% for HD). The main difference was found to be the relative percentage of thymoquinone (not found in the essential oil) and carvacryl methyl ether (1.0-1.2% for HD versus t-0.4 for SFE) which can explain the higher antioxidant activity, assessed by Rancimat test, of the SFE volatiles when compared with HD. Thymoquinone is considered a strong antioxidant compound.

Periplasmic nitrate reductase revisited: a sulfur atom completes the sixth coordination of the catalytic molybdenum

J Biol Inorg Chem. 2008 Jun;13(5):737-53. doi: 10.1007/s00775-008-0359-6

Incorporation of either molybdenum or tungsten into formate dehydrogenase from Desulfovibrio alaskensis NCIMB 13491; EPR assignment of the proximal iron-sulfur cluster to the pterin cofactor in formate dehydrogenases from sulfate-reducing bacteria

J Biol Inorg Chem (2004) 9: 145–151 DOI 10.1007/s00775-003-0506-z

Sulfur fractions and carbon-nitrogen-phosphorus-sulfur relationships in some Brazilian and Iowa soils

O atual conhecimento relativo à distribuição em percentagem das várias frações de enxofre nos solos provem principalmente dos estudos dos solos de regiões temperadas. Em vista disso, este estudo foi conduzido para determinar as frações do S e as relações C-N-P-S em alguns solos da região subtropical dos Estados de São Paulo e do Paraná, Brasil, e comparar estes valores nestes solos com aqueles nos solos do Estado de Iowa, dos Estados Unidos da América do Norte. As análises das frações de enxofre nos solos dos dois países, indicaram que os solos do Brasil contem sulfato inorgânico adsorvido. Expressos como percentagem do S total, os solos do Brasil acusaram de 5 a 23% (média 11%) de S-sulfato inorgânico, de 20 a 65% (média 40%) de S-ester sulfato, de 5 a 12% (média 7%) de S-ligado ao Carbono e de 24 a 59% (média 42%) de S orgânico não identificado. As percentagens correspondentes nos solos de Iowa foram de 2 a 8% (média 5%) de S-sulfato inorgânico, de 43 a 60% (média 50%) de S-ester sufato, de 7 a 18% (média 11%) de enxofre ligado ao carbono e de 30 a 39% (média 34%) de S orgânico, não identificado. Outrossim, não foi encontrado o enxofre inorgânico não-sulfato em nenhum dos solos analisados. Houve grandes variações nas relações C, N, Ρ e S entre solos brasileiros quando comparados com aqueles do Iowa.

Paper del sulfur d'hidrogen com a neurotransmissor a nivell dels sistema nerviòs entèric

Al llarg dels últims anys l’òxid nítric (NO) i el monòxid de carboni (CO) han estat investigats com dos neurotransmissors gasosos del tracte gastrointestinal. Algunes dades demostren que el sulfur d’hidrogen (H2S) podria ser el tercer neurotransmissor gasos a nivell central i perifèric. Objectiu: valorar si el H2S compleix els requisits per ser considerat com el tercer neurotransmissor gasos a nivell del sistema nerviós entèric. Mètodes: la motilitat espontània de preparacions de múscul llis circular de mostres de còlon sigma humà i còlon mig de rata es van determinar in vitro mitjançant la tècnica de banys d’òrgans. El hidrogensulfur de sodi (NaHS) va ser utilitzat com donador de H2S. Resultats: 1- El NaHS va inhibir de forma concentració depenent la motilitat espontània en presència de bloqueig neural amb Tetrodotoxina (TTX 1 μM) (IC50 101±18 μM rata n=10; 329±86 μM humà n=18). 2- Aquesta relaxació es va veure reduïda per ODQ 10 μM, un inhibidor de la guanilat ciclasa, en còlon mig de rata (n=5). En humà a més de ser reduïda per ODQ 10μM (n=6), també ho va ser per SQ 22,536 100 μM (n=10), un inhibidor de l’adenilat ciclasa, i per L-NNA 1 mM (n=8), un inhibidor de la sintesi de NO. 3- En còlon de rata la incubació amb D,L-Propargilglicina 2 mM (PAG), un inhibidor de la síntesi de H2S, va incrementar la motilitat tant en situació control (10,05±2,06 vs 17,46±3,37 g•min-1 AUC, P&0,001, n=10) com en presència de TTX 1μM (14,45±7,28 vs 21,67±10,05 g•min-1 AUC, P&0,01, n=7). Conclusió: el H2S compleix part dels criteris per ser considerat un neurotransmissor gasos inhibitori en el tracte gastrointestinal: la inhibició de la seva síntesi incrementa la motilitat intestinal i la seva addició exògena produeix relaxació de la musculatura llisa intestinal.

Síntesi i estudi de les propietats de fotoluminescència de nanoestructures de sulfur de cadmi

S’han sintetitzat estructures de CdS a partir de sílice mesoporosa (SBA-15, SBA-16 i KIT-6) pel mètode del motlle rígid i s’han caracteritzat mitjançant TEM i XRD, i se n’han estudiat les seves propietats de fotoluminescència mitjançant CSLM. Els resultats obtinguts s’han comparat amb una mostra de CdS comercial. El CdS SBA-15 ha conservat l’estructura mesoporosa del motlle, mentre que en els altres dos casos s’ha mantingut només de manera parcial. Per a totes les mostres, la mida de partícula es troba en el rang dels 3-10 nm. Pel que fa a l’estructura, s’ha detectat fase wurtzita i zinc-blenda, en diferents percentatges entre elles. La formació de wurtzita pot ser en part responsable del col·lapse parcial de la mesostructura. El pic de màxima emissió en l’espectre de fotoluminescència es desplaça entre les diferents estructures segons la mida de partícula. L’amplada del pic varia en funció del grau de dispersió de partícula, de manera que s’observa que aquesta és inferior en les mostres sintetitzades respecte de la comercial.

The importance of root-produced volatiles as foraging cues for entomopathogenic nematodes

Background Entomopathogenic nematodes (EPNs) are tiny parasitic worms that parasitize insects, in which they reproduce. Their foraging behavior has been subject to numerous studies, most of which have proposed that, at short distances, EPNs use chemicals that are emitted directly from the host as host location cues. Carbon dioxide (CO2) in particular has been implicated as an important cue. Recent evidence shows that at longer distances several EPNs take advantage of volatiles that are specifically emitted by roots in response to insect attack. Studies that have revealed these plant-mediated interactions among three trophic levels have been met with some disbelief. Scope This review aims to take away this skepticism by summarizing the evidence for a role of root volatiles as foraging cues for EPNs. To reinforce our argument, we conducted olfactometer assays in which we directly compared the attraction of an EPN species to CO2 and two typical inducible root volatiles. Conclusions The combination of the ubiquitous gas and a more specific root volatile was found to be considerably more attractive than one of the two alone. Hence, future studies on EPN foraging behavior should take into account that CO2 and plant volatiles may work in synergy as attractants for EPNs. Recent research efforts also reveal prospects of exploiting plant-produced signals to improve the biological control of insect pests in the rhizosphere.