Propyl Disulfide Research Articles

Evaluation of insecticidal activity of the essential oil of Allium chinense G. Don and its major constituents against Liposcelis bostrychophila Badonnel

Water-distilled essential oil from the dried bulbs of Allium chinense (Liliaceae) was analyzed by gas chromatography–mass spectrometry (GC–MS). Eighteen compounds, accounting for 98.4% of the total oil, were identified and the main components of the essential oil of A. chinense were methyl allyl trisulfide (30.7%), dimethyl trisulfide (24.1%), methyl propyl disulfide (12.8%) and dimethyl disulfide (9.6%) followed by methyl allyl disulfide (3.4%) and methyl propyl trisulfide (3.6%). The essential oil exhibited contact toxicity against the booklice (Liposcelis bostrychophila) with an LC50 value of 441.8μg/cm2 while the two major constituents, dimethyl trisulfide and methyl propyl disulfide had LC50 values of 153.0μg/cm2 and 738.0μg/cm2 against the booklice, respectively. The essential oil of A. chinense possessed strong fumigant toxicity against the booklice with an LC50 value of 186.5μg/l while methyl allyl trisulfide (LC50=90.4μg/l) and dimethyl trisulfide (LC50=114.2μg/l) exhibited stronger fumigant toxicity than methyl propyl disulfide (LC50=243.4μg/l) and dimethyl disulfide (LC50=340.8μg/l) against the booklice. The results indicated that the essential oil and its major constituents have potential for development into natural insecticides or fumigants for control of insects in stored grains.

Evaluation of larvicidal activity of the essential oil of Allium macrostemon Bunge and its selected major constituent compounds against Aedes albopictus (Diptera: Culicidae).

BackgroundDuring the screening programme for new agrochemicals from Chinese medicinal herbs and local wild plants, the essential oil of dried bulbs of Allium macrostemon Bunge (Liliaceae) was found to possess larvicidal activity against mosquitoes. The aim of this research was to determine the larvicidal activity of the essential oil and its major constituent compounds against the larvae of the Culicidae mosquito, Aedes albopictus.MethodsEssential oil of A. macrostemon was obtained by hydrodistillation and analyzed by gas chromatography (GC) and gas chromaotography-mass spectrometry (GC-MS). The activity of the essential oil and its two major constituents were evaluated, using World Health Organization (WHO) procedures, against the fourth instar larvae of Ae. albopictus for 24 h and larval mortalities were recorded at various essential oil/compound concentrations ranging from 9.0 - 150 μg/ml.ResultsThe essential oil of A. macrostemon exhibited larvicidal activity against the early fourth instar larvae of Ae. albopictus with an LC50 value of 72.86 μg/ml. The two constituent compounds, dimethyl trisulfide and methyl propyl disulfide possessed strong larvicidal activity against the early fourth instar larvae of Ae. albopictus with LC50 values of 36.36 μg/ml and 86.16 μg/ml, respectively.ConclusionThe results indicated that the essential oil of A. macrostemon and its major constituents have good potential as a source for natural larvicides.

On-line mass spectrometric analysis of sulfur compounds in hydrothermal process of durian and vegetables

In this work is presented online monitoring of gasification of durian (Durio zibethinus), onion (Allium cepa L.) and garlic (Allium sativum L.) as real biomasses containing sulfuric compounds, in sub and near critical water (250, 300 and 350°C) by Lithium Ion Attachment Mass Spectrometry. Seven sulfuric compounds were detected in the resulting gas phase: H2S, ethanethiol, 1-propanethiol, methyl phenyl disulfide, propyl disulfide, diethyl trisulfide and dipropyl trisulfide gases. Allicin and alliin were successfully detected from onion and garlic samples. The effect of the subcritical conditions used on the release of sulfur heteroatomic compounds from real biomass was examined. Ca(OH)2 was adopted as an alkali reagent to suppress the emission of sulfuric compounds to the gas phase. Extraction was promoted and decomposition processes were observed for durian when Ca(OH)2 was added. For onion and garlic samples the decomposition process was prevailing with the addition of Ca(OH)2.

Supercritical CO2 Extraction Optimization of Onion Oil Using Response Surface Methodology

AbstractResponse surface methodology was employed to optimize the conditions of supercritical CO2 extraction of the oil from freeze‐dried onion powder. The effects of pressure, temperature and extraction time on the yield of oil were investigated. The maximum extraction yield of 4.69 ± 0.04 g/kg dry basis was achieved at a pressure of 20.6 MPa, a temperature of 40.6 °C, a time of 260 min, a CO2 flow rate of 22 L h–1, and an entrainer ratio of 0.1 mL absolute ethanol per gram dry basis. The chemical composition of the oil was analyzed by gas chromatography‐mass spectrometry. The most representative compounds of the essential oil were organosulfur‐containing compounds and, among these, the main constituents were methyl 5‐methylfuryl sulfide (18.30 %), methyl 3,4‐dimethyl‐2‐thienyl disulfide (11.75 %) and 1‐propenyl propyl disulfide (9.72 %).

Toxicity mechanisms of onion (Allium cepa) extracts and compounds in multidrug resistant erythroleukemic cell line.

Onion (Allium cepa) is being studied as a potential anticancer agent, but little is known regarding its effect in multidrug resistance (MDR) cells. In this work, the cytotoxicity of crude onion extract (OE) and fractioned extract (aqueous, methanolic and ethyl acetate), as well as some onion compounds (quercetin and propyl disulfide) were evaluated in Lucena MDR human erythroleukemic and its K562 parental cell line. The capacity of OE to induce apoptosis and/or necrosis in these cells, the possible participation of oxidative stress and DNA damage were also assessed. Similar sensitivities were obtained for both tumoral cells, however only OE caused significant effects in the cells. In K562 cells, a significant increase of apoptosis was verified while the Lucena cells experienced a significant increase of necrosis. An antioxidant capacity was verified for OE discarding oxidative damage. However, OE provoked similar significant DNA damage in both cell lines. Thus, the OE capacity to overcome the MDR phenotype suggests anti-MDR action of OE.

Volatile compounds of the cultivated dumebuchu (Allium senescens L. var. senescens)

This study was conducted to examine the volatile compounds of cultivated dumebuchu (Allium senescens L. var. senescens). Dumebuchu is listed as a rare plant in Korea by Korea National Arboretum and has peculiar and long-lasting odor which resembles the flavor of garlic and onion. The volatile compounds of the cultivated dumebuchu were extracted by solid phase microextraction (SPME) and analyzed by gas chromatography-mass spectrometry (GCMS). The field-cultivated dumebuchu had a larger amount of terpene compounds than greenhouse-cultivated one. The total of 9 sulfur containing compounds was identified in the cultivated dumebuchu. The most abundant compound was dipropyl disulfide and the second most abundant compound was propyl allyl disulfide. Additionally, carboxen/polydimethylsiloxane (CAR/PDMS) fiber was found to be more efficient than PDMS fiber for extracting sulfur containing compounds from the cultivated dumebuchu.

양파추출농축액(오니웰TM)의 저장 중 휘발성 향기성분 변화

양파추출농축액(오니웰<TEX>$^{TM}$</TEX>)의 저장 유통과정 중 품질유지를 위한 척도로서 관능적요소 중 가장 중요한 휘발성 향기성분을 저장기간(<TEX>$30^{\circ}C$</TEX>, 150일) 동안 분석하였다. 총 23종의 휘발성화합물이 동정되었는데, 이는 함황 화합물류 9종, 카르보닐 화합물류 5종, 퓨란류 4종, 방향족 화합물류 2종 및 기타 화합물류 3종이었다. 함황 화합물류는 전체함량의 80.3~62.6%로 중요한 향기성분임을 알 수 있었다. 이 중 dimethyl trisulfide가 50.1~42.1% 범위로 함황 화합물류 중에서 가장 높은 함량을 차지하였다. 총 함황 화합물류의 함량은 저장기간과 함께 증가하였는데, 특히 신선한 양파향의 dimethyl disulfide와 마늘향의 methyl propyl disulfide 함량이 유의적으로 증가하였다(p<0.05). 가열반응에 의해 생성된 4종의 퓨란류(furfural, 2-acetylfuran, 5-methyl-2-furfural, furfurylalcohol)가 동정되었는데, 함량면에서 함황 화합물 다음으로 많았다(14.2~12.9%). 이 중 furfural이 전체 퓨란류의 61.9~49.4%를 차지하였고, 저장기간과 함께 유의적으로 증가하였다. 카르보닐 화합물에서는 알데히드류가 4종, 케톤 1종으로 총 5종이 검출되었다. 함량면에서는 6.2~4.8% 범위로 퓨란류 다음으로 많았으며, 가열에 의한 지방산화 분해에 의해 생성된 화합물로 동정되었다. 따라서 이들 가열반응에 의해 유도된 퓨란류나 알데히드류가 양파 특유의 함황 화합물과 함께 양파추출농축액(오니웰<TEX>$^{TM}$</TEX>)의 풍미에 기여할 것으로 추정되었다. The study was conducted to identify volatile flavor compounds in concentrated onion extracts (<TEX>$Oniwell^{TM}$</TEX>) during storage at <TEX>$30^{\circ}C$</TEX> for 150 days. A total of 23 compounds was detected in samples by solid phase microextraction (SPME)/GC/MSD, consisting mainly of 9 sulfur-containing compounds, 5 carbonyl compounds, 4 furans, 2 aromatic compounds and 3 miscellaneous compounds. The sulfur-containing compounds were major compounds with ranges of 75.8~67.3% of total volatiles. In particular, dimethyl trisulfide, with a cooked cabbage-like odor, was 50.1~42.1% of the total amount of sulfur-containing compounds. Two compounds, dimethyl disulfide (fresh garlic/green onion-like) and methylpropyl disulfide (garlic salt-like), were significantly increased with longer storage periods (p<0.05). Four furans (furfural, 2-acetylfurn, 5-methyl-2-furfural, furfurylalcohol), known as thermally generated flavors, ranged from 14.2~12.9% of total volatiles, and the amounts of 4 aldehydes (2-, 3-methylbutanal, benzaldehyde, phenylactaldehyde) derived from lipid oxidation during heat treatment were followed in that order. Accordingly, it was estimated that these 3 groups including sulfur-containing compounds, furans and aldehydes played key roles in flavors in concentrated onion extracts (<TEX>$Oniwell^{TM}$</TEX>) during storage.

Toxicity mechanisms of onion (Allium cepa) extracts and compounds in multidrug resistant erythroleukemic cell line

Onion (Allium cepa) is being studied as a potential anticancer agent, but little is known regarding its effect in multidrug resistance (MDR) cells. In this work, the cytotoxicity of crude onion extract (OE) and fractioned extract (aqueous, methanolic and ethyl acetate), as well as some onion compounds (quercetin and propyl disulfide) were evaluated in Lucena MDR human erythroleukemic and its K562 parental cell line. The capacity of OE to induce apoptosis and/or necrosis in these cells, the possible participation of oxidative stress and DNA damage were also assessed. Similar sensitivities were obtained for both tumoral cells, however only OE caused significant effects in the cells. In K562 cells, a significant increase of apoptosis was verified while the Lucena cells experienced a significant increase of necrosis. An antioxidant capacity was verified for OE discarding oxidative damage. However, OE provoked similar significant DNA damage in both cell lines. Thus, the OE capacity to overcome the MDR phenotype suggests anti-MDR action of OE.

Zinc Surfactant Effects on Improved Mechanical Properties of Silica-Filled Silicone Rubber/Natural Rubber Blends Using TESPD Coupling Agent

Abstract Zinc surfactant (ZS) is added into natural rubber (NR)/silica/TESPD (bis (triethoxysilyl propyl) disulfide) and silicone rubber (SR)/NR/silica/TESPD compounds and these compounds are vulcanized. The addition of the ZS shows significant improvements on mechanical properties on both compounds. It increases the torque maximum values of the compounds as well as the tan values, which is an indirect implication that the vibration isolation property is increased. It shows the presence of zinc ion in the ZS helps silane coupling with double bond in the rubber chain. This results in improved mechanical properties such as the modulus, tensile strength, elongation at break, and hardness.

Effects of Selected Organo-sulfur Compounds on Melanin Formation

The effect of organo-sulfur compounds, including 1-propylmercaptan (PM), dimethyl disulfide (DMDS), diallyl disulfide (DADS), propyl disulfide (PDS), and 2,5-dimethylthiophene (DMT), on melanin formation was investigated. Among the selected five organo-sulfur compounds, PM displayed a significant inhibitory effect on tyrosinase activity (IC(50) = 0.5 mM) and the highest inhibitory action on o-quinone formation. In the B16 intracellular model system, the inhibitory action of selected five organo-sulfur compounds on tyrosinase activity and melanin formation may be, in part, attributed to the reduction of the reactive oxygen species (ROS) formation and positive modulation of the GSH/GSSG ratio in B16 cells. Among the five organo-sulfur compounds, PM appeared to be the most potent inhibitor of melanin formation. The analysis of inhibitory kinetics revealed that PM is a mixed-type inhibitor. This is the first study indicating that organo-sulfur compounds tested may play an important role in the regulation of melanin formation, making them the potent candidates for skin-whitening agents.

지역별 생산 양파종의 휘발성 향기성분 비교분석

Onion Research Institute, Gyeongnam Agricultural Research Extention Services, Gyeongnam 635-821, KoreaAbstractTo provide scientific information for processing of value-added products from onion, volatile flavor com-pounds were compared in onions harvested in 6 regions, such as Muan (Jeonnam), Buan (Jeonbuk), Andong (Gyeongbuk), and 3 regions of Gyeongnam around Changnyeong (Yueo, Jangma, Seongsan). A total of 51 com-pounds were detected in samples by solid phase microextraction (SPME)/GC/MSD and they consisted mainly of sulfur-containing compounds (20), aldehydes (4), ketones (5), esters (11), aromatic hydrocarbons (4), nitro-gen containing compounds (2), and miscellaneous compounds (5). The sulfur-containing compounds were the major compounds with ranges of 62.6～80.3% of total volatiles, regardless of harvested regions. The amounts of 5 sulfur containing compounds known as having antioxidant activity (2,4-, 2,5-dimetylthiophene, 2-vi-nyl-1,3-dithiane, 5-methoxy thiazole, and 3,5-diethyl-1,2,4-trithiolane) were the highest in Andong and fol-lowed by Yueo, Jangma, Buan, Seongsan, and Muan. However, onions from Buan region had the highest amounts of 5 sulfur-containing compounds known as having anticarcinogenic activity ((Z)-, (E)-methyl pro-penyl disulfide, (Z)-, (E)-propenyl propyl disulfide, and di-2-propenyl disulfide), followed by Yueo, Andong, Jangma, Seongsan, and Muan.Key words: onion, volatile compound, flavor, domestic

국내산 양파의 저장 중 휘발성 향기성분 비교

국내 주요 양파 생산지인 전남 무안, 전북 부안, 경북 안동 및 경남 창녕의 3개 지역(유어, 장마, 성산)에서 수거된 양파 6종을 <TEX>$0.5^{\circ}C$</TEX>에 저장하면서의 휘발성 향기성분을 분석 비교하였다. 동정된 총 45종의 화합물에서 함황화합물류(21종)이 가장 많았고, 양적으로도 <TEX>$66.9{\sim}86.9%$</TEX>를 차지하였다(저장 0일경). 함량면에서는 유어(7,582.4 ng/g)가 가장 많았고, 다음으로 성산(5,933.3 ng/g), 무안(4,043.5 ng/g), 장마(2,374.7 ng/g), 부안(2,233.3 ng/g) 및 안동( 1,516.7 ng/g) 순이었다. 저장 60일경에는 지역에 관계없이 상당량 감소하였으며, 무안(2,445.0 ng/g), 유어(2,401.7 ng/g), 성산(1,536.4 ng/g), 안동(1,306.5 ng/g), 장마(1,188.2 ng/g) 및 부안(1,183.5 ng/g) 순이었다 항산화효과가 있는 6종의 함황화합물류(2,4-,2,5-dimetylthiophene, 2-vinyl-1,3,-dithiane, 5-methoxy thiazole, 3,5-diethyl-1,2,4-trithiolane 및 isomer)는 저장 0일경에는 유어, 성산, 무안순으로 많았으나, 저장 60일경에는 유어, 무안, 성산, 안동, 장마, 부안의 순이었다. 항암효과가 있는 함황화합물류 5종((Z)-, (E)-methyl propenyl disulfide, (Z)-, (E)-propenyl propyl disulfide, di-2-propenyl disulfide)은 저장0일에는 유어, 성산 및 무안이 가장 높았으나, 저장 60일 경에는 무안, 유어, 성산, 부안 및 장마 순이었다. Volatile flavor compounds of onions were analyzed and compared during storage at <TEX>$0.5^{\circ}C$</TEX>, which harvested in 6 regions, such as Muan, Buan, Andong and 3 regions of Changnyeong (Yueo, Jangma and Seongsan). A total of 45 compounds were detected in samples by solid phase microextraction (SPME)/GC/MSD, consisting mainly of sulfur-containing compounds (21), aldehydes (13), ketones (2) and miscellaneous compounds (9). The sulfur-containing compounds were major compounds with ranges of <TEX>$66.9{\sim}86.9%$</TEX> of total volatiles in 0 day of storage as regardless of harvested regions. Three regions (Yueo, Seongsan and Muan) had high amounts of over 4,043 ng/g in 0 day of storage, whereas 2 regions (Muan and Yueo) only had amounts of over 2,400 ng/g after 60 days of storage. Five sulfur-containing compounds known as having antioxidant activity (2,4-, 2,5-dimetylthiophene, 2-vinyl-1,3-dithiane, 5-methoxy thiazole and 3,5-diethyl-1,2,4-trithiolane and isomer) were the high levels in 3 regions (Yueo, Seongsan and Muan) during 60 day of storage. These 3 regions had also the highest amounts in 5 sulfur-containing compounds known as having anticarcinogenic activity ((Z)-, (E)-methyl propenyl disulfide, (Z)-, (E)-propenyl propyl disulfide, and di-2-propenyl disulfide) and kept same trend after 60 days of storage.

초임계 이산화탄소를 이용한 살균방법이 동치미의 품질에 미치는 영향

Here we studied the changes on quality characteristics of Dongchimi by supercritical carbon dioxide to manufacture Dongchimi of high quality. There were no distinctive changes of acidity, pH, color difference, free sugar and organic acid of the Dongchimi treated with supercritical , compared to the control. The content of vitamin C in Dongchimi, which was treated with supercritical (at 25 MPa, ) was 0.826 mg/mL, and was similar to that of 0.1 MPa. Unpleasant volatile compounds such as dimethyl disulfide, metyl trisulfide and methyl propyl disulfide in Dongchimi were decreased by supercritical ; also, treatment of supercritical was useful to improve flavor of Dongchimi. Polygalacturonase activity was decreased 40.3% after supercritical carbon dioxide treatment at 25 MPa and .

Alternative Reagents for Chemical Noise Reduction in Liquid Chromatography–Mass Spectrometry Using Selective Ion–Molecule Reactions

Reduction of ionic chemical background noise based on selective gas-phase reactions with chosen neutral reagents has been proven to be a very promising approach in liquid chromatography-mass spectrometry (LC-MS). In this study further investigations on alternative reagents including the disulfides (dimethyl disulfide, diethyl disulfide, methyl propyl disulfide), dimethyl trisulfide, ethylene oxide, and butadiene monoxide, for example, have been carried out. Tandem mass spectrometric studies of ion/molecule reactions indicate that-besides dimethyl disulfide-ethylene oxide and butadiene monoxide also exhibit very efficient reactions with background ions. Furthermore, it is confirmed that the reactions are very selective according to the test with some analyte ions. In contrast to its rapid reactions with background ions, ethylene oxide does not react, or reacts much less, with these analytes. Therefore, it can be used as an alternative reagent for noise reduction. Although reactions of the other tested neutral reagents with background ions are evaluated, they are generally not suitable as reagents for this purpose because of lack of reactivity or dramatic ion losses during reactions.

Enzymatic Phosphatidylation of Thiamin, Pantothenic Acid, and Their Derivatives

Phospholipase D from Streptomyces sp. was found to catalyze the transfer reaction of the dipalmitoylphosphatidyl residue from 1,2-dipalmitoyl-3-sn-phosphatidylcholine to thiamin, pantothenic acid, and their derivatives in a biphasic system. The following phosphatidylated compounds were synthesized: 1,2-dipalmitoyl-3-sn-phosphatidylthiamin, 1,2-dipalmitoyl-3-sn-phosphatidylthiamin propyl disulfide, 1,2-dipalmitoyl-3-sn-phosphatidylthiamin tetrahydrofurfuryl disulfide, 1,2-dipalmitoyl-3-sn-phosphatidylpantothenic acid, and 1,2-dipalmitoyl-3-sn-phosphatidyl-pantothenyl ethyl ether.

산지별 마늘의 향기 항산화활성과 열처리 효과

The objectives of this study were to compare the aroma characteristics and antioxidant activity of raw and heated garlic (130℃, 2 hr) from different cultivation areas (Danyang, Seosan, Uiseong Namhae, Namdo, Daeseo and China). The volatile compounds were extracted by simultaneous steam distillation extraction and identified with gas chromatography/mass spectrometer. The major volatile compounds of raw garlic were sulfur compounds such as diallyl disulfide, methyl-2-propenyl trisulfide, di-2-propenyl trisulfide etc. After heating, the major volatile compounds were allyl mercaptan, methyl pyrazine, 2,2-dimethyl-1,3-dithiane, 2-propenyl propyl disulfide, allyl methyl sulfide, allyl alcohol, and allyl sulfide etc. The DPPH radical scavenging activity (EDA, %) of volatile compounds from raw garlic and heated garlic was increased in a dose-dependent manner. The antioxidant activities (EDA, %) of volatile compounds from raw garlic cultivated in Danyang, Namhae and China were 20.07, 34.62, and 9.71% respectively. After heating, these values were increased to 79.90, 93.59, and 77.26% respectively. Results showed that heat treatment significantly enhanced the antioxidant activities (EDA, %) of the garlic.

Identification of Characteristic Aroma Components of Thai Fried Chili Paste

Three forms of Thai fried chili pastes (CP) were prepared, consisting of an unheated CP (UH-CP), a CP heated at 100 degrees C for 25 min (H25-CP, typical product), and a CP excessively heated for 50 min (H50-CP). The potent odorants in the CPs were investigated by two gas chromatography-olfactometry methods: dynamic headspace dilution analysis (DHDA) and aroma extract dilution analysis (AEDA). DHDA revealed that the predominant odorants in heated CPs were mainly sulfur-containing compounds, followed by lipid-derived compounds, Strecker aldehydes, and Maillard reaction products. Dimethyl sulfide, allyl mercaptan, 2- (or 3-) methylbutanal, ally methyl sulfide, 2,3-butanedione, 3,3'-thiobis(1-propene), and methyl propyl disulfide were among the most potent headspace odorants detected by DHDA. By AEDA, 2-vinyl-4 H-1,3-dithiin and diallyl trisulfide had the highest FD factors in H25-CP. On the basis of their high FD factors by both GCO methods, the predominant odorants in H25-CP were 3-vinyl-4 H-1,2-dithiin, allyl methyl disulfide, and allyl methyl trisulfide. Furthermore, dimethyl trisulfide and diallyl disulfide had the highest odor activity values in H25-CP, suggesting that these were also potent odorants in CP. In addition, methional, 3-methylbutanoic acid, 4-hydroxy-2,5-dimethyl-3-(2 H)-furanone, and 3-hydroxy-4,5-dimethyl-2( 5H)-furanone (sotolon) were indicated as potent thermally derived odorants of H25-CP.

Human brain activation in response to olfactory stimulation by intravenous administration of odorants

To identify the BOLD effects related to olfaction in humans, we recorded functional magnetic resonance imaging (fMRI) scans in response intravenously instilled thiamine propyl disulfide (TPD) and thiamine tetrahydrofurfuryl disulfide monohydrochloride (TTFD). TPD and TTFD evoked a strong and weak odor sensation, respectively. Since we did not spray the odor stimuli directly, this method is expected to reduce the effect caused by direct stimulation of the trigeminal nerve. For the analysis of fMRI data, statistical parametric mapping (SPM2) was employed and the areas significantly activated during olfactory processing were located. Both strong and weak odorants induced brain activities mainly in the orbitofrontal gyrus (Brodmann's area: BA 11) in the left hemisphere. TPD (a strong odorant) induced activity in the subthalamic nucleus in the left hemisphere and the precentral gyrus (BA 6) and insula in the right hemisphere. TTFD (a weak odorant) induced activity in the superior frontal gyrus (BA 11) in the right hemisphere. In both circumstances, there was an increase in blood flow at the secondary olfactory cortex (SOC) but not the primary olfactory cortex (POC), probably due to a habituation effect in the POC. From the present results, we found brain activity in not only odor-specific regions but also regions whose levels of activity were changed by an intensity difference of odor stimuli.

Adsorption and structural properties of channel-like and cage-like organosilicas

Channel-like and cage-like mesoporous silicas, SBA-15 (P6mm symmetry group) and SBA-16 (Im3m symmetry group), were modified by introducing single ureidopropyl surface groups, mixed ureidopropyl and mercaptopropyl surface groups, and single bis(propyl)disulfide bridging groups. These hexagonal and cubic organosilicas were prepared under acidic conditions via co-condensation of tetraethyl orthosilicate (TEOS) and proper organosilanes using poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) amphiphilic block copolymer templates, P123 (EO20PO70EO20) and F127 (EO106PO70EO106). The modified SBA-15 and SBA-16 materials were synthesized by varying the molar ratio of organosilane to TEOS in the initial synthesis gel. The removal of polymeric templates, P123 and F127, was performed with ethanol/hydrochloric acid solution. In the case of SBA-15 the P123 template was fully extracted, whereas this extraction process was less efficient for the removal of F127 template from the SBA-16-type organosilicas; in the latter case a small residue of F127 was retained. The adsorption and structural properties of the resulting materials were studied by nitrogen adsorption-desorption isotherms at −196∘C (surface area, pore size distribution, pore volumes), powder X-Ray diffraction, CHNS elemental analysis and high-resolution thermogravimetry. The structural ordering, the BET specific surface area, pore volume and pore size decreased for both channel-like and cage-like mesoporous organosilicas with increasing concentration of incorporated organic groups.

Neuromagnetic Changes of Brain Rhythm Evoked by Intravenous Olfactory Stimulation in Humans

To identify the changes in the respective frequency band and brain areas related to olfactory perception, we measured magnetoencephalographic (MEG) signals before and after instilling intravenously thiamine propyl disulfide (TPD) and thiamine tetrahydrofurfuryl disulfide monohydrochloride (TTFD), which evoked a strong and weak sensation of odor, respectively. For the frequency analysis of MEG, a beamformer program, synthetic aperture magnetometry (SAM), was employed and event-related desynchronization (ERD) or synchronization (ERS) was statistically determined. Both strong and weak odors induced ERD in (1) beta band (13-30 Hz) in the right precentral gyrus, and the superior and middle frontal gyri in both hemispheres, (2) low gamma band (30-60 Hz) in the left superior frontal gyrus and superior parietal lobule, and the middle frontal gyrus in both hemispheres, and (3) high gamma band 2 (100-200 Hz) in the right inferior frontal gyrus. TPD induced ERD in the left temporal, parietal and occipital lobes, while TTFD induced ERD in the right temporal, parietal and occipital lobes. The results indicate that physiological functions in several regions in the frontal lobe may change and the strength of the odor may play a different role in each hemisphere during olfactory perception in humans.