3S Group Research Articles

Evaluation of antibody and T Cell immunity response in different immunization groups of inactive and mRNA COVID-19 vaccines

This study aimed to evaluate the antibody and T cell responses of homologous and heterologous booster doses for SARS-CoV-2 vaccines. Our study was performed on those with two doses of mRNA vaccine BNT162b2 (2B, n:44), those with heterologous booster dose BNT162b2 vaccine after two doses of inactivated vaccine CoronaVac (2S+1B, n:44), those with homologous booster dose vaccine CoronaVac after two doses of vaccine CoronaVac (3S, n:44) SARS-CoV-2 IgG antibody levels were significantly higher in individuals who received heterologous boosters(p<0.001). IFN-Ɣ, IL-2 and IL-13 median values were detected higher in 2S+1B group than in 3S group, respectively (p=0.112, p=0.057, p=0.341). Although the antibody levels in 2S+1B group were similar (p=0.153) to the 2B group; IFN-Ɣ, IL-2 and IL-13 levels were higher (p<0.001). In conclusion, supplementing an improved strategy based on inactivated vaccines with an mRNA vaccine as a heterologous booster is likely to be more beneficial in the course of the pandemic.

Effect of Rapid Polymerization on Water Sorption and Solubility of Bulk-fill Composites.

The aim of the study was to examine the impact of rapid high-intensity polymerization on water sorption and solubility of a new generation of bulk-fill composite materials. Five materials were tested: a conventional composite Filtek Z250 (3M, St. Paul, USA) and four bulk-fill composites, Filtek One Bulk Fill (3M), Tetric PowerFill (Ivoclar Vivadent, Schaan, Liechtenstein), Tetric PowerFlow (Ivoclar Vivadent), SDR Plus (Dentsply, Konstanz, Germany). Composite specimens with a 9-mm diameter and a 2-mm height (n = 6) were polymerized with a high-intensity curing unit (Bluephase® PowerCure, Ivoclar Vivadent). The control group was polymerized for a total of 40 s on both sides (1193 mW / cm2) and 3s group for 3 s on one side (3053 mW/cm2). Water sorption and solubility were measured by ISO 4049 method up to 30 days of immersion. The results were statistically analyzed using one-way ANOVA with Tukey post-hoc correction. Different polymerization protocols for the same material were compared by t-test (p <0.05). The 3s polymerization protocol increased the solubility of all materials. Filtek One Bulk Fill showed the highest water sorption and solubility values, and Tetric PowerFlow proved to be a stable material with low values of tested parameters. During immersion, a saturation of specimens was achieved in low-viscosity bulk-fill composites within two weeks, while in other materials it was not achieved within 30 days, or more, following the immersion. Rapid polymerization caused an increase in solubility, which could affect the biocompatibility of the investigated materials not intended for the 3s curing. SDR Plus and Filtek One Bulk Fill should not be polymerized with rapid high-intensity curing due to increased solubility that exceeds ISO 4049:2009 limits.

Dominance hierarchies within different size groupings of Nile tilapia (Oreochromis niloticus) and effects on growth and physiological responses

Hierarchies are prevalent in social animals and display of aggression by dominant individuals often results in appetite and growth suppressions in lower-ranked fish. This study investigated the effects of dominance hierarchies on growth and some physiological responses in Nile tilapia (mass range: 120–300 g). Fish were grouped based on body mass into three classifications of one dominant and three subordinates (1D:3S), two dominants and two subordinates (2D:2S) and four equal-sized (4ES) individuals, and each grouping was triplicated. Rates of aggressive interactions under conditions of food deprivation, hypoxia and increased temperature stressors were also assessed. The 4ES treatment was characterised by more frequent aggressive interactions, compared with the other groupings. The number of lost scales recovered from the different groups after 24 h of group formations were significantly higher in the 1D:3S group. Food deprivation resulted in progressively increasing rates of aggressive interactions up to 48 h, but decreased at 72 h in all treatments. Feed intake for the 4ES group was significantly higher for than the other groups, because access to feed was largely unrestricted for all individuals. The lower-ranked individuals in the 1D:3S and 2D:2S groups had lower growth rates, compared with the dominants. Subordinate fish under treatment 1D:3S and dominant individuals in 2D:2S had elevated mean red blood cells, haemoglobin, haematocrit and white blood cell counts relative to other fish. Although aggression counts were highest in the 4ES group, the results of this study provide evidence ensuring homogeneous weights improve feed intake and growth in Nile tilapia.

Nasal Reconstruction With Two Stages Versus Three Stages Forehead Fap: What is Better for Patients With High Vascular Risk?

In nasal reconstruction, it is necessary to replace all anatomic layers in order to reinstate correct aesthetics. The most apt donor site to use in order to cover the nose has been recognized as forehead skin. Traditionally 2 phases are required to reconstruct the forehead flap; however, an intermediate third phase was described by Millard which is between transfer of the flap and division of the pedicle. These methods will be compared in this study with regard to both complication rates and aesthetic results in high vascular risk patients.46 patients were enrolled in the study, all of whom were undergoing either total or subtotal nasal reconstruction from January 2001 to March 2018. The 2-step technique (2S Group) was performed on 30 patients and the 3-step technique (3S Group) was performed on 16. Evaluation questionnaires were completed by patients and a plastic surgeon who was extraneous to the study to evaluate aesthetic satisfaction. Complications other than flap necrosis such as infection, wound dehiscence and hematoma were recorded. VAS and Likert mean values, used to evaluate aesthetic satisfaction, were examined with a Student t test and were discovered to be relevant. Complication rates studied with Fisher exact test showed no statistically significant difference between the 2 groups. The 3-phase method for nose reconstruction using a forehead flap represents a better functional and aesthetic option for patients at high vascular risk.

The Histopathologic Correlation of Bosniak 3 Cyst Subclassification

ObjectiveTo evaluate the histopathologic correlation of recently described subclassification of Bosniak category 3 cysts (3s and 3n). Materials and MethodsA total of 106 patients who underwent partial/radical nephrectomy due to a complex renal cyst (≥Bosniak 3) were retrospectively reviewed. All the scans of the patients were reevaluated by 2 experienced uroradiologists. Bosniak 3 cysts were reclassified as 3n (nodularity on the cyst wall/septae) and 3s (septated cysts without nodularity) as described in a recently published paper. Group 1 consisted of patients with Bosniak 3s, Group 2 consisted of patients with Bosniak 3n, and Group 3 consisted of patients with Bosniak 4 cysts. Three groups were compared according to patients' characteristics, radiological findings, histopathologic results, and survival outcomes. ResultsThere were 52 patients in Bosniak 3 group and 54 patients in Bosniak 4 group. Mean follow-up was 35.3 months. Among Bosniak 3 cysts, 37 lesions were classified in 3s and 15 were classified in 3n. Malignancy was higher in 3n group than 3s (86.7% vs 54.1%, P= .026). Lesion size was significantly lower for malignant cysts compared to benign ones in the patients with Bosniak 3 lesions (44.2 ± 27.5 vs 80 ± 55.9 P= .005). In the subgroups, malignant lesions were significantly smaller than benign lesions in 3s group similar to general Bosniak 3 group. Most of the Bosniak 3 lesions were organ confined and low grade. ConclusionThe subclassification of Bosniak 3 cysts as 3s and 3n can help to differentiate highly suspicious malignant lesions from the relatively less suspicious ones.

Effective transformation of cellulose to 5-hydroxymethylfurfural catalyzed by fluorine anion-containing ionic liquid modified biochar sulfonic acids in water

This article first discloses that the fluorine anion-containing ionic liquids-functionalized biochar sulfonic acids (BCSA-IL-F1–3s), which were simply synthesized by an ionic exchange of 1-trimethoxysilylpropyl-3-methylimidazolium chloride (IL-Cl) grafted on the BCSA with CF3SO3H (HF1), HBF4 (HF2), HPF6 (HF3), respectively, can efficiently catalyze cellulose hydrolysis into reducing sugars (RSs) and 5-hydroxymethyl furfural (HMF) in water under microwave irradiation. This process provides a very high catalysis efficiency (turnover numbers, 4.03–4.89) at mild temperature (80 °C) for 3 h, but also possesses an excellent repeatability. More outstandingly, they can achieve much higher HMF yields (12.70–27.94%) compared to the IL-Cl-functionalized BCSA catalyst (HMF yields are lower than 0.1%) under the same reaction conditions. This is likely because the introduction of IL-F1–3s groups can significantly improve the accessibility, acidity and thermal stability of BCSA’s SO3H sites, as supported by evidence from a solid 31P NMR spectrum and thermogravimetric analysis. It is proposed that the good selectivity for HMF perhaps originates from a co-catalysis action of the IL-F1–3s and SO3H groups on BCSA-IL-F1–3s in the further conversion of RSs to HMF.

P0032 Effect of compression therapy on chemotherapy-induced peripheral neuropathy in breast cancer treatment: Investigation into restored skin microcirculation homeostasis

Background To prevent and treat chemotherapy-induced peripheral neuropathy (CIPN) in breast cancer patients, our hospital applies a “3S” approach based on two concepts: compression therapy, using stockings and sleeves, and medication therapy, using selected prophylactic medications. Although we previously reported significantly superior peripheral neuropathy grade suppression and nab-paclitaxel dose maintenance in a 3S group compared to a control group, effects of 3S treatment on skin microcirculation homeostasis is unclear. The aim of this study was to study the effect of compression therapy on restoring skin microcirculation homeostasis patients with breast cancer with CIPN. Methods This small-scale clinical study took place in a single centre in Nagasaki, Japan, and involved 22 patients with breast cancer who were treated with nab-paclitaxel with 3S treatment ( n = 44 lower limb samples) and a control group of 25 healthy female volunteers ( n = 50). Compression stockings were applied for 24 h on 47 participants (in patients treated with nab-paclitaxel, just before intravenous infusion). Tissue blood flow (TBF) of lower limbs was measured with a laser Doppler blood-flow metre, both before and after application. The main outcome measure was the Stability Index (SI; standard deviation of TBF/mean TBF), which represents TBF homeostasis, where low values indicate normal, stable blood flow and high values indicate impairment. Findings In 44 patient samples, the mean SI decreased significantly after stocking use, from 11.6 ± 6.3 to 8.7 ± 3.4 ( p p Interpretation Our study suggests that patients treated with nab-paclitaxel have poor tissue-fluid exchange homeostasis, relative to healthy controls, and that stable skin microcirculation may be effectively restored through compression therapy. Therefore, our 3S approach may alleviate CIPN by proactively maintaining skin microcirculation homeostasis and, thereby, also potentially raising drug clearance in the skin.

Abstract P5-15-13: Restoration by compression therapy of skin blood perfusion levels decreased during breast cancer chemotherapy, alleviating peripheral neuropathy

Abstract &amp;lt;Background&amp;gt; Nanoparticle albumin-bound paclitaxel (nab-PTX) has become a key drug used in chemotherapy for breast cancer, but it often causes adverse effects such as peripheral neuropathy (PN). No effective prophylactic management has so far been established. We have applied a "3S" approach to prevent and treat PN based on two concepts: compression therapy using stockings and sleeves, and medication therapy using selected prophylactic medications. We previously reported better CTCAE v4.0 PN grades and notably superior nab-PTX dose maintenance in a 3S group compared to a control group. However, little is known about the effects of compression therapy on a patient’s level of skin blood perfusion; it is also unknown whether any such effects might vary by 1) PN grade or 2) the number of nab-PTX cycles. &amp;lt;Patients and Methods&amp;gt; To establish whether a compression therapy-skin perfusion relationship exists, the skin perfusion of the lower limbs was measured before and after stocking use in a 3S prophylactic treatment group for nab-PTX therapy (n=44), and in a control group of healthy volunteers (n=50). The skin perfusion was measured using a laser Doppler blood flow meter with an integrated probe (NL-101 Nahri Nexis Japan). To find how compression therapy affects skin perfusion by PN grade, the 3S group was subdivided into three PN grade subgroups (n = 12 for Grade 0, n = 20 for Grade 1, and n = 12 for Grades 2 and 3 combined). To find how compression therapy affects skin perfusion by number of nab-PTX treatment cycles undergone by patients, the 3S group was subdivided into the following three subgroups: 1 to 5 cycles of nab-PTX treatment (first period group; 1P, n=18), 6 to 10 cycles (second period group; 2P, n=16), and more than 10 cycles (third period group; 3P, n=12). &amp;lt;Results&amp;gt; In the control group of healthy volunteers, stocking use tended to increase the median skin perfusion level (mL/min/100g) from 10.9 ± 3.8 to 11.8 ± 4.3 (p=0.06). Interestingly, the median skin perfusion level for the 3S group as a whole significantly increased from 8.7 ± 3.3 before stocking use to 11.3 ± 3.8 after stocking use (p&amp;lt; 0.001). When examining the effects of stocking use on skin perfusion by PN grade, the increase in median skin perfusion level was significant in the Grade 0 subgroup (8.2 ± 2.7 to 12.4 ± 4.5, p=0.005), in the Grade 1 subgroup (8.3 ± 3.8 to 10.4 ± 4.0, p=0.0499), and in the Grades 2 and 3 subgroup (7.9 ± 2.3 to 10.6 ± 2.4, p=0.005). When examining the effects of stocking use on skin perfusion by number of treatment cycles, the increase in median skin perfusion level was significant in the 1P subgroup (7.9 ± 3.0 to 11.4 ± 4.8, p=0.007) and in the 2P (7.9 ± 2.9 to 10.8 ± 2.9, p=0.005), but not in the 3P (9.3 ± 3.5 to 10.8 ± 3.2, p=0.15). &amp;lt;Conclusion&amp;gt; This study demonstrated that the skin perfusion of the lower limbs is decreased following nab-PTX chemotherapy, and also that the skin perfusion is improved by compression therapy. Compression therapy appeared to successfully restore the skin perfusion levels across every grade of chemotherapy-induced PN. Therefore, our 3S approach is suitable for alleviating CIPN by proactively maintaining skin perfusion from the beginning of nab-PTX therapy. Citation Format: Tsuyoshi Ohno, Takashi Mine, Hiroki Yoshioka, Mikiko Kosaka, Kazuhiro Matsuda, Maiko de Kerckhove, Charles de Kerckhove. Restoration by compression therapy of skin blood perfusion levels decreased during breast cancer chemotherapy, alleviating peripheral neuropathy [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-15-13.

Photoelastic stress analysis of mandibular fixed prostheses supported by 3 dental implants.

To observe the photoelastic stress patterns generated around implants in relation to variations in the diameter and total number of implants supporting fixed complete-arch mandibular frameworks. Three different implant configurations were analyzed (n = 3): 5 standard implants with diameters of 3.75 mm (C), 3 standard implants with diameters of 3.75 mm (3S), and 3 wide implants with diameters of 5.0 mm (3W). The samples were subjected to a vertical compressive load (1.33 kgf) applied at the end of the distal cantilever of the framework. The shear stresses were calculated around the implants, and the data were analyzed using one-way analysis of variance. The implants nearest to the loading showed higher stress values regardless of the group. The C group showed lower shear stress when compared with the other groups (P = 0.001). No significant difference was observed between the 3W and 3S groups (P = 0.785). A reduction in the number of implants, regardless of the implant diameter, showed higher stress concentration around the implants. Five-implant configuration showed lower stress concentration and seems to be more biomechanically predictable.

The Relationship Between the Grade of Peripheral Neuropathy and the Skin Blood Perfusion in Chemotherapy-Induced Peripheral Neuropathy Patients, and the Effects of Compression Therapy

ABSTRACT Aim: Nanoparticle albumin-bound paclitaxel (nab-PTX) has become a key drug used in chemotherapy for breast cancer, but it often causes adverse effects such as peripheral neuropathy (PN). No effective prophylactic management has so far been established. We have applied a “3S” approach to prevent and treat PN based on two concepts: compression therapy using stockings and sleeves, and medication therapy using selected prophylactic medications. We previously reported better CTCAE v4.0 grades and notably superior nab-PTX dose maintenance in a 3S group compared to a control group with no prophylactic treatment. However, little is known about the effects of compression therapy on the relationship between PN and the skin blood perfusion. Methods: The skin perfusion of the lower limbs was measured before and after stocking use in a 3S prophylactic treatment group for nab-PTX therapy (n = 50), and in a control group of healthy volunteers (n = 50). The 3S group was subdivided by PN grade for a subsequent analysis (n = 18 for Grade 0, n = 22 for Grade 1 and n = 10 for Grades 2 and 3 combined). The skin perfusion was measured using a laser Doppler blood flow meter with an integrated probe (NL-101 Nahri Nexis Japan). Results: In the control group of healthy volunteers, stocking use tended to increase the median skin perfusion level (mL/min/100g) from 10.9 ± 3.8 to 11.8 ± 4.3. Interestingly, the median skin perfusion level for the 3S group as a whole significantly increased from 8.7 ± 3.3 before stocking use to 11.3 ± 3.8 after stocking use (p Conclusions: This study demonstrated that the skin perfusion of the lower limbs is decreased following nab-PTX chemotherapy, and also that compression therapy can successfully restore the skin perfusion levels in nab-PTX patients across every grade of peripheral neuropathy. This apparent restoration in skin perfusion may increase the drug clearance, which could potentially alleviate peripheral neuropathy. Disclosure: All authors have declared no conflicts of interest.

PO102 PACLITAXEL INDUCED CIPN – CAN IT BE CONTROLLED?

peripheral sensory disturbance and the peripheral blood flow. In our attempts to treat peripheral neuropathy, we have applied two concepts: compression therapy using stockings and sleeves and prophylactic therapy, including goshajinkigan, to control adverse nonhematologic effects due to nab-PTX for breast cancer. Aim: This study aimed to elucidate whether prophylactic treatment, including stockings, sleeves and certain drugs (3S), is effective for preventing nab-PTX-induced peripheral neuropathy. Patients and Methods: Fourteen patients with recurrent, metastatic or locally advanced breast cancer were included and treated with nabPTX at a dose of 260 mg/m2 every three weeks at our hospital from June 2012 to April 2013. The patients were divided into two groups: a prophylactic treatment (3S) group (n=7) and a control group (n=7). In the 3S group, the patients wore stockings and sleeves from the beginning of nab-PTX administration for 24 hours and concurrently received prophylactic drugs, including goshajinkigan (7.5 g/day), mecobalamin (1,500 μg/day) and lafutidine (20 mg/day). The grade of peripheral neuropathy evaluated according to the definition of CTCAE v4.0 and total administered dose were compared between the two groups. Results: After the initial treatment with nab-PTX, peripheral neuropathy appeared in five of the seven patients in the control group and in only one of seven patients in the 3S group (p = 0.014). After four cycles of nab-PTX, the grade of peripheral neuropathy in the 3S group was better than that observed in the control group (p < 0.01). The mean dose in the 3S group was 86.7 mg/m2/week, which is significantly better than that observed in the control group (63.4 mg/m2/week, p< 0.01). Conclusions: 3S treatment controls the grade of neuropathy, resulting in the maintenance of the total dose of nab-PTX in breast cancer patients.

Starvation and re-feeding affect Hsp expression, MAPK activation and antioxidant enzymes activity of European Sea Bass (Dicentrarchus labrax)

In the context of food deprivation in fish (wild and farmed), understanding of cellular responses is necessary in order to develop strategies to minimize stress caused by starvation in the aquaculture section. The present study evaluates the effects of long term starvation (1F–3S: one-month feeding–three-month starvation) and starvation/re-feeding (2S–2F: two-month starvation–two-month re-feeding) compared to the control group (4F–0S: four-month feeding–zero month starvation) on cellular stress response and antioxidant defense in organs, like the intestine, the liver, the red and white muscle of European sea bass Dicentrarchus labrax. Molecular responses were addressed through the expression of Hsp70 and Hsp90, the phosphorylation of stress-activated protein kinases and particularly p38 mitogen-activated protein kinase (p38 MAPK) and the extracellular signal-regulated kinases (ERK-1/2). For the determination of the effect of the oxidative stress caused by food deprivation and/or re-feeding, the (maximum) activities of antioxidant enzymes such as glutathione peroxidise (GPx), catalase (CAT) and superoxide dismutase (SOD) as well as the determination of thiobarbituric acid reactive substances (TBARS) were studied. The experimental feeding trials caused a tissue distinct and differential response on the cellular and antioxidant capacity of sea bass not only during the stressful process of starvation but also in re-feeding. Specifically, the intestine phosphorylation of ERKs and antioxidant enzymatic activities increased in the 2S–2F fish group, while in the 1F–3S group an increase was detected in the levels of the same proteins except for GPx. In the liver and the red muscle of 2S–2F fish, decreased Hsp70 and phosphorylated p38 MAPK levels and increased Hsp90 levels were observed. Additionally, SOD activity decreased in the red muscle of 2S–2F and 1F–3S groups. In the liver and red muscle of 1F–3S group Hsp70 levels increased, while the activation of p38 MAPK in the liver decreased. In the white muscle, Hsp90 levels decreased and the phosphorylation of p38 MAPK increased in both feeding regimes compared to control. In the same tissue, GPx and catalase levels were decreased in 2S–2F regime, while SOD levels were decreased in 1F–3S regime.

Effect of starvation and re-feeding on reproductive indices, body weight, plasma metabolites and oxidative enzymes of sea bass ( Dicentrarchus labrax)

Feed management is an important factor for successful aquaculture, especially when it affects gonad maturation. In this context, the present study evaluates the effects of long term starvation (1F–3S: one-month feeding – three-month starvation) and starvation/re-feeding (2S–2F: two-month starvation – two-month re-feeding) on gonad maturation, hematological/biochemical indices and proximate composition of liver and muscle of vitelogenic sea bass. In males, all the fish in the control group (4F–0S: four-month feeding – zero-month starvation) reached the maturity stage S2 (Mature), while only 33% and 75% reached that stage in the 1F–3S and 2S–2F groups, respectively. In females, the percentages of immature gonads were 80%, 25% and 50% for the groups 1F–3S, 2S–2F and 4F–0S respectively, while the percentages of the fish which reached the stage of vitellogenesis were 20%, 75% and 50% for the same groups. The concentration of glucose and lactate in plasma was not affected by starvation or re-feeding. On the contrary, triglycerides, phospholipids and total lipids of group 1F–3S decreased significantly, whereas cholesterol did not differ compared to the control group. In the 2S–2F group, total lipids and cholesterol were also significantly decreased while triglycerides and phospholipids were not altered. Proximate composition analysis in the liver showed that long term starvation (1F–3S) led to a significant reduction of crude lipid and ash, compared to the 4F–0S and 2S–2F groups. In contrast, crude protein concentration in the liver was significantly increased in 1F–3S group compared to 4F–0S and 2S–2F groups. In white muscle a significant reduction of crude lipids was detected in the 1F–3S and 2S–2F groups, while no significant changes were observed in crude protein, ash and moisture concentrations. The enzymatic activities of lactate dehydrogenase (L-LDH), citrate synthase (CS) and 3-hydroxyacyl CoA dehydrogenase (HOAD) were significantly increased in the liver of 1F–3S fish, whereas in red muscle both HOAD and CS were significantly decreased in both 1F–3S and 2S–2F groups. Overall our results indicate that a 2 month starvation and 2 month re-feeding period during vitellogenesis reduces GSI and maturity stage in male sea bass and affect the levels of biochemical blood indices and the activities of certain enzymes of the intermediary metabolism.

Asymmetric phase-transfer catalytic sulfanylation of some 2-methylsulfinyl cyclanones. Modeling of the stereochemical course of the aldol reaction of (S S,2 S)-2-methylsulfinyl-2-methylsulfanylcyclohexanone

Increased diastereoisomeric excesses are obtained for the sulfanylation reactions of some 2-methylsulfinyl cyclanones under phase-transfer catalysis using the chiral catalyst QUIBEC instead of TEBA. The optically pure (S S,2 S)-2-methylsulfinyl-2-methylsulfanylcyclohexanone thus prepared reacts with ethyl acetate lithium enolate affording, after hydrolysis, ( R)-2-[(ethoxycarbonyl)methyl]-2-hydroxycyclohexanone in 60% ee. Density functional theory calculations (at the B3LYP/6-311++G(d,p) level) can successfully explain the origin of this result as the kinetically favored axial attack of the nucleophile to the carbonyl group of the most stable conformer of the cyclanone, in which the CH 3SO and CH 3S groups are at the equatorial and axial positions, respectively.

A density functional theory study of the hydrogenolysis reaction of CH 3SH to CH 4 on the catalytically active (100) edge of 2H-MoS 2

The breaking of the C S bond is a crucial step in hydrodesulfurization, the removal of the sulfur atom from sulfur-containing molecules in crude oil. Thus the hydrogenolysis reaction of CH 3SH to CH 4 was studied by means of density functional theory on the catalytically active (100) edge of 2H-MoS 2, with and without Co and Ni promoter atoms. Thiol adsorption, C S bond breaking, and the formation and desorption of CH 4 were investigated with different sulfur and hydrogen surface coverages. CH 3SH first adsorbs molecularly with its S atom in a bridging mode between two surface Mo atoms, followed by S H bond cleavage with moderate activation energy. The subsequent concerted C S bond breaking and CH 4 formation occurs through a reaction of the adsorbed CH 3S group with the H atom of a neighbouring SH group at the molybdenum sulfide surface. Sulfur atoms, hydrogen atoms adsorbed on sulfur atoms, and promoter atoms (Co and Ni) at the catalyst surface weaken the bonding of adsorbed CH 3S and lower the energy barrier for CH 4 formation. Although the reactions of thiols on the metal sulfide surface are similar to reactions on metal surfaces, the chemistry is different. The reactions occur between intermediate alkyl and hydrogen fragments bonded to sulfur atoms, not to metal atoms.

Synthesis and molecular structures of chromium-iron-sulfide and [Cp 3Cr 3(μ 3-S) 4Fe] 2Fe(CO) 3 · C 6H 6 clusters with tetrahedral metal frameworks

Oxidative decarbonylation of Fe 2(CO) 6(μ-SPh) 2 under the action of Cp 2Cr 2(SCMe 3) 2S produced the tetrahedral Cp 3Cr 3(μ 3-S) 4Fe(Sph) cluster (III) and the unique nonanuclear [Cp 3Cr 3(μ 3-S) 4Fe] 2Fe(CO) 3S·C 6H 6 cluster (IV), depending on the molecular ratio of the reagents. Both complexes were characterized by X-ray structural analysis. In IV two heterometallotetrahedra are connected via a bridging Fe(CO) 3S group and FeFe bond (3.110 Å). Cluser III may be considered as a model of ferredoxin while cluster IV could be seen as a model nitrogen fixing system.

Acylation of α-SCF 3 substituted β-carbonyl acetic acid and thiacetic acid derivatives with oxalyl chloride

α-CF 3S-substituted β-ketoacidamides, nitriles, thioamides and their Schiff bases are synthesised and their reactions with oxalyl chloride are investigated. As a new phenomenon the elimination of the CF 3S group during cylcisation to substituted 2,3,5-trioxo-1,4-oxazephine (7), 4-pyrroline-2,3-dione (9) and oxalyl (10) is observed. Factors influencing this course of the reaction and mechanism of product formation are discussed.

A quantitating reagent for methanethiolation of protein sulfhydryl groups

p-Nitrophenoxycarbonyl methyl disulfide has been synthesized for use as a quantitating agent for methanethiolation of protein sulfhydryl groups. This reagent reacts specifically and quantitatively with cysteine residues of proteins to yield an unsymmetrical disulfide containing a CH 3S group and concomitantly releases the chromophore, p-nitrophenol. Titration of the sulfhydryl groups of glyceraldehyde 3-phosphate dehydrogenase (EC 1.2.1.12) with this reagent has been studied. Incorporation of CH 3S as measured by the release of p-nitrophenol paralleled the loss of sulfhydryl group dependent activity of the enzyme. The enzyme was found inactive on modification of four of the eight sulfhydryl groups present in the enzyme. Stability of p-nitrophenoxycarbonyl methyl disulfide has also been studied in different buffer systems. The rate of decomposition of the p-nitrophenyl ester due to hydrolysis was found negligible below a pH of 8.0 compared to its rate of reaction with free sulfhydryl groups.

A 19F NMR study of steric hindrance and intramolecular coordination in organo-mercury, -tin and -lead derivatives of 2,6-dimethyl-4-fluorothiophenol and 2,6-dibromo-4-fluorothiophenol

Some organomercury, -tin and -lead derivatives of 2,6-dimethyl-4-fluorothiophenol and 2,6-dibromo-4-fluorothiophenol of the general type R p MSAr have been prepared. The fluorine chemical shifts of the compounds realtive to internal fluorobenzene and the 19F SCS values for the corresponding substituents have been determined and discussed in terms of steric hindrance and intramolecular coordination, the behaviour of the organometallic substituents R n MS in these respects being compared with that of the SH and CH 3S groups. The anomalously low steric requirements of R n MS groups, as well as the differences in the strength of intramolecular coordination and its influence on the acceptor power of the metal atom, in the compouds of mercury, tin and lead have been demonstrated.

A 19F NMR study of electronic effects in organomercury, -tin and -lead derivatives of some fluorophenols and fluorothiophenols

A number of organomercury, -tin and -lead derivatives of m- and p-fluoro-substituted phenols and thiophenols of the type R n MOAr and R n MSAr have been prepared. The 19F chemical shifts relative to fluorobenzene have been measured in various solvents for all these compounds. On the basis of the data obtained, the electronic features of the substituents R n MO and R n MS have been studied and compared with those of OH, CH 3O, SH and CH 3S groups. The influence of various factors on the electronic effect of the organometallic substituent and on its solvent susceptibility is discussed. The coordinating abilities of the substituents (C 2H 5) 3SnO and (C 2H 5) 3-SnS in solution have been compared with those of the OH and SH groups.