High efficiency removal of NO using waste calcium carbide slag by facile KOH modification

Waste calcium carbide slags (CS), which are widely applied to desulfurisation, are not typically used in denitration. Herein, to well achieve waste control by waste, a facile and high-efficiency denitration strategy is developed using KOH to modify the calcium carbide slags (KCS). Various KCS samples were investigated using a series of physical and chemical characterisations. The performance test results showed that the KOH concentration and reaction temperature are the main factors affecting the denitration efficiency of KCS, and CS modified with 1.5 mol/L KOH (KCS-1.5) can achieve 100% denitration efficiency at 300°C. Such excellent removal efficiency is due to the catalytic oxidation of the oxygen-containing functional groups derived from the KCS. Further studies showed that KOH treatment significantly increased the concentration of oxygen vacancies, nitro compounds, and basic sites of CS. This study provides a novel strategy for the resource utilisation of waste CS in the future.

Surface-Activated Ti3C2Tx Adsorption of Acetylene Black Coupled with Polyaniline as a Signal Tag for the Detection of the ESAT-6 Antigen of Mycobacterium tuberculosis

Early secretory antigenic target-6 (ESAT-6) is regarded as the most immunogenic protein produced by Mycobacterium tuberculosis, whose detection is of great clinical significance for tuberculosis diagnosis. However, the detection of the ESAT-6 antigen has been hampered by the expensive cost and complex experimental procedures, resulting in low sensitivity. Herein, we developed a titanium carbide (Ti3C2Tx)-based aptasensor for ESAT-6 detection utilizing a triple-signal amplification strategy. First, acetylene black (AB) was immobilized on Ti3C2Tx through a cross-linking reaction to form the Ti3C2Tx-AB-PAn nanocomposite. Meanwhile, AB served as a conductive bridge, and Ti3C2Tx can synergistically promote the electron transfer of PAn. Ti3C2Tx-AB-PAn exhibited outstanding conductivity, high electrochemical signals, and abundant sites for the loading of ESAT-6 binding aptamer II (EBA II) to form a novel signal tag. Second, N-CNTs were adsorbed on NiMn layered double hydride (NiMn LDH) nanoflowers to obtain NiMn LDH/N-CNTs, exhibiting excellent conductivity and preeminent stability to be used as electrode modification materials. Third, the biotinylated EBA (EBA I) was immobilized onto a streptavidin-coated sensing interface, forming an amplification platform for further signal enhancement. More importantly, as a result of the synergistic effect of the triple-signal amplification platform, the aptasensor exhibited a wide detection linear range from 10 fg mL-1 to 100 ng mL-1 and a detection limit of 4.07 fg mL-1 for ESAT-6. We envision that our aptasensor provides a way for the detection of ESAT-6 to assist in the diagnosis of tuberculosis.

Chemical structure of hydrocarbons significantly affects removal performance and microbial responses in gas biotrickling filters

The control of emissions of short-chain hydrocarbons with different structures is critical for the petrochemical industry. Herein, three two-carbon-containing (C2) hydrocarbons, ethane, ethylene, and acetylene, were chosen as pollutants to study the effects of chemical structure of hydrocarbons on removal performance and microbial responses in biotrickling filters. Results showed that the removal efficiency (RE) of C2 hydrocarbons followed the sequence of acetylene > ethane > ethylene. When the inlet loading rate was 30 g/(m3·h) and the empty bed residence time was 60 s, the RE of ethane, ethylene, and acetylene was 57 ± 4.0 %, 49 ± 1.0 %, and 84 ± 2.7 %, respectively. The high water solubility resulted in the high removal of C2 hydrocarbons, while a low surface tension enhanced the removal of C2 hydrocarbons. Additionally, the microbial community, enzyme activity, and extracellular properties of microorganisms also contributed to the difference in C2 hydrocarbon removal. These results could be referred for the effective control of light hydrocarbon emissions.

Acetylenic tricyclic bis-(cyano enone) interacts with Cys 374 of actin, a residue necessary for stress fiber formation and cell migration

The migratory and invasive potential of tumour cells relies on the actin cytoskeleton. We previously demonstrated that the tricyclic compound, TBE-31, inhibits actin polymerization and here we further examine the precise interaction between TBE-31 and actin. We demonstrate that iodoacetamide, a cysteine (Cys) alkylating agent, interferes with the ability of TBE-31 to interact with actin. In addition, in silico analysis identified Cys 217, Cys 272, Cys 285 and Cys 374 as potential binding sites for TBE-31. Using mass spectrometry analysis, we determined that TBE-31 associates with actin with a stoichiometric ratio of 1:1. We mutated the identified cysteines of actin to alanine and performed a pull-down analysis with a biotin labeled TBE-31 and demonstrated that by mutating Cys 374 to alanine the association between TBE-31 and actin was significantly reduced, suggesting that TBE-31 binds to Cys 374. A characterization of the NIH3T3 cells overexpressing eGFP-actin-C374A showed reduced stress fiber formation, suggesting Cys 374 is necessary for efficient incorporation into filamentous actin. Furthermore, migration of eGFP-Actin-WT expressing cells were observed to be inhibited by TBE-31, however fewer eGFP-Actin-C374A expressing cells were observed to migrate compared to the cells expressing eGFP-Actin-WT in the presence or absence of TBE-31. Taken together, our results suggest that TBE-31 binds to Cys 374 of actin to inhibit actin stress fiber formation and may potentially be a mechanism through which TBE-31 inhibits cell migration.

Highly Sensitive and Selective Acetylene CuO/ZnO Heterostructure Sensors through Electrospinning at Lean O2 Concentration for Transformer Diagnosis

Acetylene (C2H2) is a gas that can cause explosions in transformers even at low concentrations. Gas chromatography (GC) or photoacoustic spectroscopy (PAS) have been used to detect C2H2 during dissolved gas analysis (DGA), but they are not suitable for monitoring numerous transformers at substations. Even though metal oxide semiconductor (MOS) based C2H2 sensors have drawn much attention as a potential solution, existing MOS-based C2H2 sensors have low sensitivity toward C2H2 in the transformer environment (<2% O2 concentrations). This study develops high-performance C2H2 gas sensors for DGA using a heterostructure of CuO/ZnO (CZ) via the electrospinning process. Performance of various ratios of CZ composite nanofibers are compared in a transformer-like environment, and the optimal composition of CZ nanofibers for detection of C2H2 at 2% O2 concentration is proposed. The CuO:ZnO = 8:2 (CZ2) sensor achieves the highest response (Rg/Ra = 7.6 against 10 ppm of C2H2) toward low concentration of C2H2 at 200 °C with good stability (>10 h). In addition, the CZ2 sensor also shows a high selectivity (>5 times) to coexisting transformer oil gases which are H2, CH4, C2H4, C2H6, CO, and CO2. Overall, this study is the first to demonstrate a high performing DGA sensor under 2% O2 concentration that can provide a practical solution to monitoring the low concentration of C2H2 in transformers effectively.

Physiological and biochemical variations of naturally ripened mango (Mangifera Indica L.) with synthetic calcium carbide and ethylene

To meet the increasing consumer demands for fruits, the implementation of artificial ripening techniques using synthetic chemicals has become increasingly commonplace among less ethical fruit production companies in today's global market. The objective of present work was to establish a difference in the physiological and biochemical and profiles of naturally ripened mangoes vs. those ripened by application of synthetic calcium carbide and ethylene. The application of calcium carbide at 10 g/kg mangoes resulted early ripening in 2 days, with a 3-day shelf life, as compared with 5 and 6 days, for mangoes ripened by ethylene and naturally, respectively. Higher levels of calcium carbide reduced moisture, fiber, protein and carbohydrates content and increased the ash content of mangoes, as compared to higher levels of ethylene, whereas in naturally ripened mangoes the content percentages were 80.21, 3.57, 3.05 6.27 and 4.74, respectively. Artificial ripening resulted in significant loss of ascorbic, citric and malic acid, as values were recorded 35.94, 2.12 and 0.63 mg/g, respectively, in mangoes ripened with 10 g/kg of calcium carbide. However, in naturally ripened mangoes the amounts of these acids were recorded significantly (p < 0.05) high as 52.29, 3.76 and 1.37 mg/g, respectively. There was an increase in total soluble solids (TSS) and reducing sugars, and a decrease in titratable acidity in calcium carbide (10 g/kg) treated mangoes. Elemental analyses revealed high levels of minerals in naturally ripened mangoes, with significant values of iron (0.45 mg/100 g), zinc (0.24 mg/100 g) and copper (0.17 mg/100 g). The organoleptic quality of the fruit decreased significantly (p < 0.05) as a result of the use of calcium carbide. Although use of artificial ripening techniques provides speedy ripening of mangoes, there are obvious limitations. Consequently, natural ripening should be promoted in order to have safer and more nutritious mangoes.

Characterization of photosynthetic Bradyrhizobium sp. strain SSBR45 isolated from the root nodules of Aeschynomene indica

We isolated a novel strain of Bradyrhizobium sp., SSBR45, from the nodulated roots of Aeschynomene indica and labeled it with Discosoma sp. red fluorescent protein (dsRED) or enhanced green fluorescent protein (eGFP) and determined its draft genomic sequence. The labeled SSBR45 stimulated the growth of A. indica markedly on a nitrogen-free medium, as observed by visualizing the fluorescent root nodules. The nodulated roots also exhibited high acetylene reduction activities. The SSBR45 genome included genes involved in nitrogen fixation, photosynthesis, and type IV secretion system; however, it did not consist of canonical nodABC genes and type III secretion system genes. SSBR45, a novel species of the genus Bradyrhizobium, consisted of an average nucleotide identity and average amino acid identity of 87% and 90%, respectively, with the closest strain B. oligotrophicum S58.

An intelligent alkyne-tag for Raman imaging of living cells: graphdiyne-encapsulated Au nanospheres

A new graphdiyne-encapsulated Au nanosphere (Au@GDY) material was fabricated, which possessed an amplified Raman signal of acetylene linkage and produced bright, stable, and distinct signals in the cellular Raman-silent region. Its signal repeatability is far superior to that of alkyne-containing molecules. This work provides promise as an alkyne-tag for Raman imaging of living cells.

Carbon dioxide capture with aqueous calcium carbide residual solution for calcium carbonate synthesis and its use as an epoxy resin filler

Calcium carbide residue (CCR) is a waste obtained from the production of acetylene gas by the hydration reaction of calcium carbide. This residue is generated in large quantities annually and requires appropriate disposal. The main composition of the residue is calcium hydroxide (Ca(OH)2). Ca(OH)2 can react with CO2 gas and form CaCO3 particles. This process is well known but not very attractive since Ca(OH)2 is obtained from limestone using an energy-intensive thermal conversion process. This paper examined the synthesis of CaCO3 from CCR solutions by capturing CO2 with the aid of triethanolamine (TEA) solutions at doses of 0, 5, 10 and 20% w/w. The precipitated CaCO3 was characterized, and the application of CaCO3 as a filler in epoxy resin was tested. The results showed that the precipitated CaCO3 was mainly calcite, with a 76.6% yield. Cubic calcite was primarily obtained in TEA solutions, whereas small and agglomerated spherical vaterite and cubic calcite particles were formed in non-TEA solutions. The CaCO3-filled epoxy composites showed higher compressive strength than the neat resin. However, the transparency of specimen plates was reduced. These results can serve as guidelines for the application of CCR slurry filtrate obtained from the sedimentation ponds of acetylene plants and help to reduce the amount of wastewater that needs to be treated. CO2 gas from industrial flue gas combined with TEA solution could be applied to precipitate CaCO3 for carbon-neutral manufacturing.

Reductive dechlorination of trichloroethene by sulfided microscale zero-valent iron in fresh and saline groundwater: Reactivity, pathways, and selectivity

S/mZVI is a promising material for groundwater remediation due to its excellent properties. However, the reactivity and electron selectivity toward target contaminant are critical. Thus, this study investigated the effect of complex groundwater chemistries (Milli-Q water, fresh groundwater and saline groundwater) on the reactivity of S/mZVI toward trichloroethylene (TCE), dechlorination pathway, hydrogen evolution kinetic, electron efficiency and aging behaviors. Results showed that sulfidation appreciably increased the reactivity and electron selectivity. The major degradation product of TCE dechlorination by S/mZVI was acetylene, which was consistent with TCE dechlorination by β-elimination. Moreover, reductive β-elimination was still the dominant dechlorination pathway for the application of S/mZVI in three groundwater conditions. However, the rates and the quantities of major products from TCE degradation varied significantly. S/mZVI in saline groundwater can maintain the reactivity towardTCE due to the protection of Fe0 by Fe3O4 deposited on the surface. Thus, the higher TCE removal efficiency and less hydrogen accumulation resulted in the greatest electron efficiency (4.3-79.2%). Overall, S/mZVI was more effective for the application in saline groundwater. This study proved insight into the comprehensive evaluation and implications for the application of S/mZVI based technologies in saline contaminated groundwater.

Phenyl dialkynylcarbinols, a Bioinspired Series of Synthetic Antitumor Acetylenic Lipids

A series of 25 chiral anti-cancer lipidic alkynylcarbinols (LACs) were devised by introducing an (hetero)aromatic ring between the aliphatic chain and the dialkynylcarbinol warhead. The resulting phenyl-dialkynylcarbinols (PACs) exhibit enhanced stability, while retaining cytotoxicity against HCT116 and U2OS cell lines with IC50 down to 40 nM for resolved eutomers. A clickable probe was used to confirm the PAC prodrug behavior: upon enantiospecific bio-oxidation of the carbinol by the HSD17B11 short-chain dehydrogenase/reductase (SDR), the resulting ynones covalently modify cellular proteins, leading to endoplasmic reticulum stress, ubiquitin-proteasome system inhibition, and apoptosis. Insights into the design of LAC prodrugs specifically bioactivated by HSD17B11 vs its paralogue HSD17B13 were obtained. The HSD17B11/HSD17B13-dependent cytotoxicity of PACs was exploited to develop a cellular assay to identify specific inhibitors of these enzymes. A docking study was performed with the HSD17B11 AlphaFold model, providing a molecular basis of the SDR substrates mimicry by PACs. The safety profile of a representative PAC was established in mice.

Anti-inflammatory acetylenic meroterpenoids from the ascidian-derived fungus Amphichorda felina SYSU-MS7908

A combination strategy of 13C NMR and bioinformatics was established to expedite the discovery of acetylenic meroterpenoids from the ascidian-derived fungus Amphichorda felina SYSU-MS7908. This approach led to the identification of 13 acetylenic meroterpenoids (1-13) and four biogenic analogs (14-17), including five new ones named felinoids A-E (1-4 and 15). Their structures and absolute configurations were elucidated using extensive spectroscopy, ECD quantum chemical calculations, and single-crystal X-ray diffraction analysis. Compound 1 possessed a rare cyclic carbonate in natural acetylenic meroterpenoids. The plausible shikimate-terpenoid biosynthetic pathways of 1-4 were also postulated. Five of these isolates exhibited anti-inflammatory activity by inhibiting NO production in LPS-induced RAW264.7 cells (IC50 = 11.6-19.5 μM). Moreover, oxirapentyn E diacetate showed a dose-dependent inhibition of pro-inflammatory cytokines IL-6 and TNF-α. Structural modification of oxirapentyn B yielded 29 new derivatives, among which seven showed improved activity (IC50 < 3 μM) and higher selectivity index (SI > 22). The structure-activity relationship study indicated that 7, 8-epoxy, and 6-acylation were crucial for the activity. These findings may provide a powerful tool to accelerate the discovery of new fungal acetylenic meroterpenoids for future anti-inflammatory drug development.

Reciprocal Interactions of Abiotic and Biotic Dechlorination of Chloroethenes in Soil

Chloroethenes (CEs) as common organic pollutants in soil could be attenuated via abiotic and biotic dechlorination. Nonetheless, information on the key catalyzing matter and their reciprocal interactions remains scarce. In this study, FeS was identified as a major catalyzing matter in soil for the abiotic dechlorination of CEs, and acetylene could be employed as an indicator of the FeS-mediated abiotic CE-dechlorination. Organohalide-respiring bacteria (OHRB)-mediated dechlorination enhanced abiotic CEs-to-acetylene potential by providing dichloroethenes (DCEs) and trichloroethene (TCE) since chlorination extent determined CEs-to-acetylene potential with an order of trans-DCE > cis-DCE > TCE > tetrachloroethene/PCE. In contrast, FeS was shown to inhibit OHRB-mediated dechlorination, inhibition of which could be alleviated by the addition of soil humic substances. Moreover, sulfate-reducing bacteria and fermenting microorganisms affected FeS-mediated abiotic dechlorination by re-generation of FeS and providing short chain fatty acids, respectively. A new scenario was proposed to elucidate major abiotic and biotic processes and their reciprocal interactions in determining the fate of CEs in soil. Our results may guide the sustainable management of CE-contaminated sites by providing insights into interactions of the abiotic and biotic dechlorination in soil.

Presence and activity of nitrogen-fixing bacteria in Scots pine needles in a boreal forest: a nitrogen-addition experiment

Endophytic nitrogen-fixing bacteria have been detected and isolated from the needles of conifer trees growing in North American boreal forests. Because boreal forests are nutrient-limited, these bacteria could provide an important source of nitrogen for tree species. This study aimed to determine their presence and activity in a Scandinavian boreal forest, using immunodetection of nitrogenase enzyme subunits and acetylene-reduction assays of native Scots pine (Pinus sylvestris L.) needles. The presence and rate of nitrogen fixation by endophytic bacteria were compared between control plots and fertilized plots in a nitrogen-addition experiment. In contrast to the expectation that nitrogen-fixation rates would decline in fertilized plots, as seen, for instance, with nitrogen-fixing bacteria associated with bryophytes, there was no difference in the presence or activity of nitrogen-fixing bacteria between the two treatments. The extrapolated calculated rate of nitrogen fixation relevant for the forest stand was 20 g N ha-1 year-1, which is rather low compared with Scots pine annual nitrogen use but could be important for the nitrogen-poor forest in the long term. In addition, of 13 colonies of potential nitrogen-fixing bacteria isolated from the needles on nitrogen-free media, 10 showed in vitro nitrogen fixation. In summary, 16S rRNA sequencing identified the species as belonging to the genera Bacillus, Variovorax, Novosphingobium, Sphingomonas, Microbacterium and Priestia, which was confirmed by Illumina whole-genome sequencing. Our results confirm the presence of endophytic nitrogen-fixing bacteria in Scots pine needles and suggest that they could be important for the long-term nitrogen budget of the Scandinavian boreal forest.

Sulfoximine Assisted C-H Activation and Annulation via Vinylene Transfer: Access to Unsubstituted Benzothiazines

In this study, we report the synthesis of unsubstituted 1,2-benzothiazines through a redox-neutral Rh(III)-catalyzed C-H activation and [4+2]-annulation of S-aryl sulfoximines with vinylene carbonate. Notably, the introduction of an N-protected amino acid ligand significantly enhances the reaction rate. The key aspect of this redox-neutral process is the utilization of vinylene carbonate as an oxidizing acetylene surrogate and an efficient vinylene transfer agent. This vinylene carbonate enables the cyclization with the sulfoximine motifs, successfully forming a diverse array of 1,2-benzothiazine derivatives in moderate to good yields. Importantly, this study highlights the potential of Rh(III)-catalyzed C-H activation and [4+2]-annulation reactions for the synthesis of optically pure 1,2-benzothiazines with high enantiomeric purity.

Infrared dual-gas CH4/C2H2 sensor system based on dual-channel off-beam quartz-enhanced photoacoustic spectroscopy and time-division multiplexing technique

Highly sensitive and stable measurement of methane (CH₄) and acetylene (C₂H₂) based on a novel dual-channel off-beam quartz-enhanced photoacoustic spectroscopy and time-division multiplexing technique was realized by a compact 3D-printed gas cell with a size of 3 × 2 × 1 cm³. Two near-infrared distributed feedback diode lasers were employed to target the CH₄ absorption line at 6046.9 cm^-1 and the C₂H₂ absorption line at 6521.2 cm^-1, respectively. Second-harmonic wavelength modulation spectroscopy method was used for photoacoustic signal recovery. A minimum detection level of ∼ 7.63 parts-per-million in volume (ppmv) for CH₄ and a level of ∼ 17.47 ppmv for C₂H₂ were achieved with a 1 s lock-in integration time, leading to a normalized noise equivalent absorption (NNEA) coefficient of 7.24 × 10^-8 cm^-1·W·Hz^-1 and 3.73 × 10^-8 cm^-1·W·Hz^-1 for CH₄ and C₂H₂, respectively. Allan-Werle deviation analysis was employed to evaluate the stability and the minimum detection limit (MDL) of the developed photoacoustic CH₄/C₂H₂ dual-gas photoacoustic sensor. Owing to the high stability of the developed sensor system, an MDL of ∼ 0.73 ppmv and an MDL of ∼ 1.60 ppmv with a 100 s averaging time were achieved for CH₄ and C₂H₂, respectively.

Desulphurization mechanism and engineering practice of carbide slag

In order to give full play to the alkaline neutralization value of carbide slag and reduce the environmental hazards of carbide slag, it is of great practical significance to study the resource utilization of carbide slag. The adsorption of sulfur compounds on carbide slag was studied in the laboratory, and the process parameters of carbide slag desulfurization were explored and optimized. The specific surface area, pore distribution, and other physicochemical parameters were analyzed by XRD and SEM, which explained the changes of products and carbide slag before and after desulfurization. The test results show that carbide slag and limestone have almost the same desulfurization effect. The kinetics of carbide slag desulfurization process conforms to pseudo-first-order kinetics, and the sulfur content of calcium carbide slag reaches to 1000 mgSO₂·g^-1. A project demonstration was carried out in the gold smelting Tielu Plant of Zhenyuan Huashuo Precious Metals Development Co., Ltd., in Yunnan. The results of the 2-year demonstration project showed that the desulphurization efficiency of the four-stage series desulphurization tower exceeds 95%. The concentration of sulfur dioxide in the discharged flue gas is reduced to less than 20 mg·m^-3, which meets the requirements of ultra-low emission standard in China. Therefore, whether from theoretical research or engineering practice analysis, it is feasible to replace limestone with calcium carbide slag for flue gas desulfurization. The paper also discusses the problems existing in the demonstration project, and provides a new idea of "using waste to treat waste" in order to solve the problem of carbide slag disposal.

Biotinylation of an acetylenic tricyclic bis(cyanoenone) lowers its potency as an NRF2 activator while creating a novel activity against BACH1

The transcription factor BACH1 regulates the expression of a variety of genes including genes involved in oxidative stress responses, inflammation, cell motility, cancer cell invasion and cancer metabolism. Based on this, BACH1 has become a promising therapeutic target in cancer (as anti-metastatic target) and also in chronic conditions linked to oxidative stress and inflammation, where BACH1 inhibitors share a therapeutic space with activators of transcription factor NRF2. However, while there is a growing number of NRF2 activators, there are only a few described BACH1 inhibitors/degraders. The synthetic acetylenic tricyclic bis(cyanoenone),(±)-(4bS,8aR,10aS)-10a-ethynyl-4b,8,8-trimethyl-3,7-dioxo-3.4b,7,8,8a,9,10, 10a-octahydrophenanthrene-2,6-dicarbonitrile, TBE31 is a potent activator of NRF2 without any BACH1 activity. Herein we found that biotinylation of TBE31 greatly reduces its potency as NRF2 activator (50-75-fold less active) while acquiring a novel activity as a BACH1 degrader (100-200-fold more active). We demonstrate that TBE56, the biotinylated TBE31, interacts and promotes the degradation of BACH1 via a mechanism involving the E3 ligase FBXO22. TBE56 is a potent and sustained BACH1 degrader (50-fold more potent than hemin) and accordingly a powerful HMOX1 inducer. TBE56 degrades BACH1 in lung and breast cancer cells, impairing breast cancer cell migration and invasion in a BACH1-dependent manner, while TBE31 has no significant effect. Altogether, our study identifies that the biotinylation of TBE31 provides novel activities with potential therapeutic value, providing a rationale for further characterisation of this and related compounds.

Effects of linkage between donors on photoinduced charge transfer in one-photon and two-photon absorption of Donor-π-Donor-π-Acceptor conjugates

Photoinduced charge transfer (CT) mechanisms of two Donor-π-Donor-π-Acceptor conjugates composed of ferrocene (Fc), zinc-porphyrin (ZnP), and fullerene (C₆₀) linked by phenylene-acetylene/acetylene during the one- (OPA) and the two-photon absorption (TPA) processes are analyzed theoretically based on the density functional theory calculations and visualization methods to study the effects of linkage between the two donors on the excitation characteristics. The change of bridge affects the efficiency of superexchange CT from Fc to ZnP in the OPA process. The one-photon excitations are dominated by local transitions of ZnP and Fc, and there is almost no efficient CT from the donors to the acceptor for both the two researched structures. In contrast, the advantage of superexchange CT from ZnP to C₆₀ becomes much larger than the other transition forms during the TPA process when the linkage between ZnP and Fc is changed from acetylene to phenylene-acetylene. This linkage effect in TPA would have great significance in designing novel optoelectronic devices.

The influence of soil acidification on N2O emissions derived from fungal and bacterial denitrification using dual isotopocule mapping and acetylene inhibition

Denitrification, as both origins and sinks of N₂O, occurs extensively, and is of critical importance for regulating N₂O emissions in acidified soils. However, whether soil acidification stimulates N₂O emissions, and if so for what reason contributes to stimulate the emissions is uncertain and how the N₂O fractions from fungal (f_fD) and bacterial (f_bD) denitrification change with soil pH is unclear. Thus, a pH gradient (6.2, 7.1, 8.7) was set via manipulating cropland soils (initial pH 8.7) in North China to illustrate the effect of soil acidification on fungal and bacterial denitrification after the addition of KNO₃ and glucose. For source partitioning, we used and compared SP/δ¹⁸O mapping approach (SP/δ¹⁸O MAP) and acetylene inhibition technique combined isotope two endmember mixing model (AIT-IEM). The results showed significantly higher N₂O emissions in the acidified soils (pH 6.2 and pH 7.1) compared with the initial soil (pH 8.7). The cumulative N₂O emissions during the whole incubation period (15 days) ranged from 7.1 mg N kg^-1 for pH 8.7-18.9 mg N kg^-1 for pH 6.2. With the addition of glucose, relative to treatments without glucose, this emission also increased with the decrement of pH values, and were significantly stimulated. Similarly, the highest N₂O emissions and N₂O/(N₂O + N₂) ratios (rN₂O) were observed in the pH 6.2 treatment. But the difference was the highest cumulative N₂O + N₂ emissions, which were recorded in the pH 7.1 treatment based on SP/δ¹⁸O MAP. Based on both approaches, f_fD values slightly increased with the acidification of soil, and bacterial denitrification was the dominant pathway in all treatments. The SP/δ¹⁸O MAP data indicated that both the rN₂O and f_fD were lower compared to AIT-IEM. It has been known for long that low pH may lead to high rN₂O of denitrification and f_fD, but our documentation of a pervasive pH-control of rN₂O and f_fD by utilizing combined SP/δ¹⁸O MAP and AIT-IEM is new. The results of the evaluated N₂O emissions by acidified soils are finely explained by high rN₂O and enhanced f_fD. We argue that soil pH management should be high on the agenda for mitigating N₂O emissions in the future, particularly for regions where long-term excessive nitrogen fertilizer is likely to acidify the soils.

Pyridinic nitrogen enables dechlorination of trichloroethylene to acetylene by green rust: Performance, mechanism and applications

Carbonous materials were found to catalyze the dechlorination of trichloroethylene (TCE) by green rust (GR), but the catalytic mechanism was not fully understood. We have developed a facile ball milling method to synthesize N-doped graphene (NG) with various N species, catalyzing fast dechlorination of TCE to acetylene by GR with the highest acetylene production rate of ~0.1 d^-1. The adsorption of TCE onto NG is mainly derived from the graphene region of NG, and high pyridinic N is essential for the enhanced TCE reduction by GR. Oxygen species did not enhance the TCE reduction in GR/NG system. High dechlorination rates are correlated to a high amount of defect in NG and a high electron conductivity of NG. Pyridinic N has the highest adsorption energy for TCE among all the N species, which leads to the highest catalytic performance. High electrochemically active surface area resulted from the high content of pyridinic N facilitate the NG-catalyzed dechlorination. The acetylene production rate in real groundwater is still around one-third of that in ultrapure water. This work not only reveals the catalytic mechanism of NG-catalyzed dechlorination by GR, but also provide a feasible approach for practical remediations of TCE-contaminated groundwater using GR-NG mixture.

Formation and growth mechanisms of polycyclic aromatic hydrocarbons: A mini-review

Polycyclic aromatic hydrocarbons (PAHs) are mostly formed during the incomplete combustion of organic materials, but their importance and presence in materials science, and astrochemistry has also been proven. These carcinogenic persistent organic pollutants are essential in the formation of combustion generated particles as well. Due to their significant impact on the environment and human health, to understand the formation and growth of PAHs is essential. Therefore, the most important growth mechanisms are reviewed, and presented here from the past four decades (1981-2021) to initiate discussions from a new perspective. Although, the collected and analyzed observations are derived from both experimental, and computational studies, it is neither a systematic nor a comprehensive review. Nevertheless, the mechanisms were divided into three main categories, acetylene additions (e.g. HACA), vinylacetylene additions (HAVA), and radical reactions, and discussed accordingly.

Two-Dimensional Pd Rafts Confined in Copper Nanosheets for Selective Semihydrogenation of Acetylene

The development of highly selective and active catalysts to catalyze an industrially important semihydrogenation reaction remains an open challenge. Here, we report the design of a bimetallic Pd/Cu(111) catalyst with Pd rafts confined in a Cu nanosheet, which exhibits desirable catalytic performance for acetylene semihydrogenation to ethylene with the selectivity of >90%. Theory calculations show that Pd atoms replacing neighboring Cu atoms in Cu(111) can improve the catalytic activity by reducing the energy barrier of the semihydrogenation reaction, as compared to unsubstituted Cu(111), and can improve the selectivity by weakening the adsorption of C₂H₄, as compared to a Pd(111) surface. The presence of Pd rafts confined in Cu nanosheets effectively turns on Cu nanosheets for semihydrogenation of acetylene with high activity and selectivity under mild reaction conditions. This work offers a well-defined nanostructured Pd/Cu(111) model catalyst that bridges the pressure and materials' gap between surface-science catalysis and practical catalysis.

Sulfur Promotion in Au/C Catalyzed Acetylene Hydrochlorination

The formation of highly active and stable acetylene hydrochlorination catalysts is of great industrial importance. The successful replacement of the highly toxic mercuric chloride catalyst with gold has led to a flurry of research in this area. One key aspect, which led to the commercialization of the gold catalyst is the use of thiosulphate as a stabilizing ligand. This study investigates the use of a range of sulfur containing compounds as promoters for production of highly active Au/C catalysts. Promotion is observed across a range of metal sulfates, non-metal sulfates, and sulfuric acid treatments. This observed enhancement can be optimized by careful consideration of either pre- or post-treatments, concentration of dopants used, and modification of washing steps. Pre-treatment of the carbon support with sulfuric acid (0.76 m) resulted in the most active Au/C in this series with an acetylene conversion of ≈70% at 200 °C.

Design and experimental investigations on six-stroke SI engine using acetylene with water injection

In the present study, a four-stroke cycle gasoline engine is redesigned and converted into a six-stroke cycle engine and experimental study has been conducted using gasoline and acetylene as fuel with water injection at the end of the recompression stroke. Acetylene has been used as an alternative fuel along with gasoline and performance of the six-stroke spark ignition (SI) engine with these two fuels has been studied separately and compared. Brake power and thermal efficiency are found to be 5.18 and 1.55% higher with acetylene as compared to gasoline in the six-stroke engine. However, thermal efficiency is found to be 45% higher with acetylene in the six-stroke engine as compared to four-stroke SI engine. The CO and HC emissions were found to be reduced by 13.33 and 0.67% respectively with acetylene as compared to gasoline due to better combustion of acetylene. The NO_x emission was reduced by 5.65% with acetylene due to lower peak temperature by water injection. The experimental results showed better engine performance and emissions with acetylene as fuel in the six-stroke engine.

Ammonia nitrogen removal from acetylene purification wastewater from a PVC plant by struvite precipitation

Acetylene purification wastewater (APW) usually contains high concentrations of ammonia nitrogen (NH4-N), which is generated during the production of acetylene in a polyvinylchloride manufacturing plant. In this study, a struvite precipitation method was selected to remove NH4-N from the APW. Laboratory-scale batch experiments were performed to investigate the effects of the initial APW pH, phosphate (PO4(3-)) concentration, magnesium (Mg(2+)) concentration, and sources of PO4(3-) and Mg(2+) on NH4-N removal. The results indicated that the initial APW pH had a significant effect on the removal of NH4-N, while the other factors had relatively minor effect. The NH4-N could be effectively removed at an optimum initial APW pH of 9.5, when Na2HPO4·12H2O and MgSO4·7H2O were both applied to NH4-N at a ratio of 1.2. Under these conditions, the efficiency of removal of NH4-N, total nitrogen and chemical oxygen demand were 85%, 84% and 18%, respectively. The X-ray diffraction analysis indicated that the precipitates were dominated by struvite. The scanning electron microscopy analysis of the precipitates showed a typical morphology of stick-like and prismatic crystals with coarse surface. The energy dispersive spectroscopy analysis indicated that the precipitates contained P, O, Mg and Ca.

The effect of radio-frequency glow discharge treatment of polystyrene on the behavior of porcine chondrocytes in vitro

The aim of this study was to determine the effects of physicochemical surface properties of tissue-culture substrata on chondrocyte behavior. Polystyrene was modified by radio-frequency glow discharge (RFGD) plasma treatment with various monomers. The changes in surface properties of the modified polystyrene were verified by ESCA and water contact angle measurements. Porcine chondrocytes were seeded on these surfaces and cultured for 5 days. After 5 days of culture, the number of chondrocytes was highest on the N2 plasma-treated surface, followed by the CH2/N2 plasma-treated surface, untreated polystyrene and CF4 plasma-treated surface. The number of chondrocytes decreased with increasing water contact angle. The surface chemical properties influenced the morphology and gene expression of cultured chondrocytes. The cells cultured on the CF4 plasma-treated surface retained a round morphology characteristic of chondrocytes after day 1, while most of the cells grown on the N2 plasma-treated surface or the untreated polystyrene showed a flattened morphology. Using RT-PCR, expression of type-I collagen could not be detected in the chondrocytes cultured on the CF4 plasma-treated surface and the CH2/N2 plasma-treated surface. In contrast, the chondrocytes grown on the N2 plasma-treated surface or the untreated polystyrene surface expressed type-I collagen mRNA. This study shows that modification by RFGD treatment could modulate chondrocyte culture and gene expression.

Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects

This paper describes the development and characterization of modular, oxy-acetylene driven laboratory scale shock tubes. Such tools are needed to produce realistic blast waves in a laboratory setting. The pressure-time profiles measured at 1 MHz using high-speed piezoelectric pressure sensors have relevant durations and show a true shock front and exponential decay characteristic of free-field blast waves. Descriptions are included for shock tube diameters of 27-79 mm. A range of peak pressures from 204 kPa to 1187 kPa (with 0.5-5.6% standard error of the mean) were produced by selection of the driver section diameter and distance from the shock tube opening. The peak pressures varied predictably with distance from the shock tube opening while maintaining both a true blast wave profile and relevant pulse duration for distances up to about one diameter from the shock tube opening. This shock tube design provides a more realistic blast profile than current compression-driven shock tubes, and it does not have a large jet effect. In addition, operation does not require specialized personnel or facilities like most blast-driven shock tubes, which reduces operating costs and effort and permits greater throughput and accessibility. It is expected to be useful in assessing the response of various sensors to shock wave loading; assessing the reflection, transmission, and absorption properties of candidate armor materials; assessing material properties at high rates of loading; assessing the response of biological materials to shock wave exposure; and providing a means to validate numerical models of the interaction of shock waves with structures. All of these activities have been difficult to pursue in a laboratory setting due in part to lack of appropriate means to produce a realistic blast loading profile.

Room temperature CO and H2 sensing with carbon nanoparticles

We report on a shell-shaped carbon nanoparticle (SCNP)-based gas sensor that reversibly detects reducing gas molecules such as CO and H(2) at room temperature both in air and inert atmosphere. Crystalline SCNPs were synthesized by laser-assisted reactions in pure acetylene gas flow, chemically treated to obtain well-dispersed SCNPs and then patterned on a substrate by the ion-induced focusing method. Our chemically functionalized SCNP-based gas sensor works for low concentrations of CO and H(2) at room temperature even without Pd or Pt catalysts commonly used for splitting H(2) molecules into reactive H atoms, while metal oxide gas sensors and bare carbon-nanotube-based gas sensors for sensing CO and H(2) molecules can operate only at elevated temperatures. A pristine SCNP-based gas sensor was also examined to prove the role of functional groups formed on the surface of functionalized SCNPs. A pristine SCNP gas sensor showed no response to reducing gases at room temperature but a significant response at elevated temperature, indicating a different sensing mechanism from a chemically functionalized SCNP sensor.

Electrochemical detection of honokiol and magnolol in traditional Chinese medicines using acetylene black nanoparticle-modified electrode

INTRODUCTION

Honokiol and magnolol are the active components of Magnolia officinalis, which is a widely used traditional Chinese medicine. Their simultaneous analysis is, therefore, important for the quality control of the product.

OBJECTIVE

To establish a simple, sensitive and rapid electrochemical method for the simultaneous detection of honokiol and magnolol based on the remarkable enhancement effect of acetylene black nanoparticle (AB).

METHODOLOGY

The AB-modified electrode was prepared via solvent evaporation. The electrochemical response of honokiol and magnolol was investigated using cyclic voltammetry. The simultaneous detection was performed with differential pulse voltammetry. The method was validated in terms of linearity, sensitivity, precision and accuracy.

RESULTS

The linear range for honokiol is 0.5-300 µg/L, and the limit of detection (LOD) is 0.25 µg/L (9.4 × 10(-10)  mol/L). For magnolol, the linear range is 10-250 µg/L, and the LOD is 5 µg/L (1.88 × 10(-8)  mol/L).

CONCLUSION

The new method was successfully used to determine honokiol and magnolol in a traditional Chinese medicine called Ageratum liquid.

[Investigation of determining strontium in M. nitida Benth. var. hirsutissima. Z. Wei. by flame atomic absorption spectra]

The present paper is aimed to establish the method of determining the strontium in M. nitida Benth. var. hirsutissima. Z. Wei. by means of air-acetylene flame atomic absorption spectra, and also provide reference for the determination of the strontium in other traditional Chinese medicine. M. Nitida Benthvarhirsutissima Z. Wei. was taken as the object. The authors used nitric-perchloric acid as digestion solution to digest samples by microwave which was controlled by pressure, and used EDTA-2Na as the releasing agent to add in the samples for determining the strontium in M. nitida Benth. var. hirsutissima. Z. Wei. by FAAS. The results showed that the samples were entirely digested by microwave. The working curve was Y = 0.036 5x -0.001 1, r = 0.999 4, the range was 0-1.6 microg x mL(-1), the average recovery rate was 101.5% with RSD 2.04%, and the method detection limit was 0.008 2 microg x mL(-1) (n = 21). It is concluded that this method is simple and accurate. It has high sensitivity and can be effectively used for determining the strontium in this traditional Chinese medicine.

QSAR modeling of toxicity of diverse organic chemicals to Daphnia magna using 2D and 3D descriptors

One of the major economic alternatives to experimental toxicity testing is the use of quantitative structure-activity relationships (QSARs) which are used in formulating regulatory decisions of environmental protection agencies. In this background, we have modeled a large diverse group of 297 chemicals for their toxicity to Daphnia magna using mechanistically interpretable descriptors. Three-dimensional (3D) (electronic and spatial) and two-dimensional (2D) (topological and information content indices) descriptors along with physicochemical parameter logK(o/w) (n-octanol/water partition coefficient) and structural descriptors were used as predictor variables. The QSAR models were developed by stepwise multiple linear regression (MLR), partial least squares (PLS), genetic function approximation (GFA), and genetic PLS (G/PLS). All the models were validated internally and externally. Among several models developed using different chemometric tools, the best model based on both internal and external validation characteristics was a PLS equation with 7 descriptors and three latent variables explaining 67.8% leave-one-out predicted variance and 74.1% external predicted variance. The PLS model suggests that higher lipophilicity and electrophilicity, less negative charge surface area and presence of ether linkage, hydrogen bond donor groups and acetylenic carbons are responsible for greater toxicity of chemicals. The developed model may be used for prediction of toxicity, safety and risk assessment of chemicals to achieve better ecotoxicological management and prevent adverse health consequences.

Synthesis of tritiated tuftsin and macrophage inhibitory tripeptide via acetylenic intermediates

Acetylenic analogues of tuftsin (Thr-Dah-Pro-Arg) and of a macrophage inhibitory tripeptide (Thr-Dah-Pro) have been synthesized by conventional procedures in solution (Dah = 2,6-diamino-4-hexynoic acid). These acetylenic derivatives are intermediates for the preparation of structurally unmodified, tritiated peptides. Catalytic tritiation of Thr-Dah-Pro-Arg and of Thr-Dah-Pro has afforded the radioactive tetra- and tripeptides with specific activities of 11.4 Ci/mmol and 37 Ci/mmol, respectively.

Affinity-labeling-based introduction of a reactive handle for natural protein modification

A new chemical method to site-specifically modify natural proteins without the need for genetic manipulation is described. Our strategy involves the affinity-labeling-based attachment of a unique reactive handle at the surface of the target protein, and the subsequent selective transformation of the reactive handle by a bioorthogonal reaction to introduce a variety of functional probes into the protein. To demonstrate this approach, we synthesized labeling reagents that contain: 1) a benzenesulfonamide ligand that directs specifically to bovine carbonic anhydrase II (bCA), 2) an electrophilic epoxide group for protein labeling, 3) an exchangeable hydrazone bond linking the ligand and the epoxide group, and 4) an iodophenyl or acetylene handle. By incubating the labeling reagent with bCA, the reactive handle was covalently attached at the surface of bCA through epoxide ring opening. Either after or before removing the ligand by a hydrazone/oxime-exchange reaction, which restores the enzymatic activity, the reactive handle incorporated could be derivatized by Suzuki coupling or Huisgen cycloaddition reactions. This method is also applicable to the target-specific multiple modification in a protein mixture. The availability of various (photo)affinity-labeling reagents and bioorthogonal reactions should extend the flexibility of this strategy for the site-selective incorporation of many functional molecules into proteins.

High-sensitivity detection of TNT

We report high-sensitivity detection of 2,4,6-trinitrotoluene (TNT) by using laser photoacoustic spectroscopy where the laser radiation is obtained from a continuous-wave room temperature high-power quantum cascade laser in an external grating cavity geometry. The external grating cavity quantum cascade laser is continuously tunable over approximately 400 nm around 7.3 microm and produces a maximum continuous-wave power of approximately 200 mW. The IR spectroscopic signature of TNT is sufficiently different from that of nitroglycerine so that unambiguous detection of TNT without false positives from traces of nitroglycerine is possible. We also report the results of spectroscopy of acetylene in the 7.3-microm region to demonstrate continuous tunability of the IR source.

Methods for measuring denitrification: diverse approaches to a difficult problem

Denitrification, the reduction of the nitrogen (N) oxides, nitrate (NO3-) and nitrite (NO2-), to the gases nitric oxide (NO), nitrous oxide (N2O), and dinitrogen (N2), is important to primary production, water quality, and the chemistry and physics of the atmosphere at ecosystem, landscape, regional, and global scales. Unfortunately, this process is very difficult to measure, and existing methods are problematic for different reasons in different places at different times. In this paper, we review the major approaches that have been taken to measure denitrification in terrestrial and aquatic environments and discuss the strengths, weaknesses, and future prospects for the different methods. Methodological approaches covered include (1) acetylene-based methods, (2) 15N tracers, (3) direct N2 quantification, (4) N2:Ar ratio quantification, (5) mass balance approaches, (6) stoichiometric approaches, (7) methods based on stable isotopes, (8) in situ gradients with atmospheric environmental tracers, and (9) molecular approaches. Our review makes it clear that the prospects for improved quantification of denitrification vary greatly in different environments and at different scales. While current methodology allows for the production of accurate estimates of denitrification at scales relevant to water and air quality and ecosystem fertility questions in some systems (e.g., aquatic sediments, well-defined aquifers), methodology for other systems, especially upland terrestrial areas, still needs development. Comparison of mass balance and stoichiometric approaches that constrain estimates of denitrification at large scales with point measurements (made using multiple methods), in multiple systems, is likely to propel more improvement in denitrification methods over the next few years.

Electrochemical determination of 2-chlorophenol using an acetylene black film modified glassy carbon electrode

Herein, an insoluble acetylene black (AB) was dispersed into water in the presence of a special kind of surfactant: dihexadecyl hydrogen phosphate (DHP), resulting in a homogeneous and stable AB-DHP suspension. Thus, a novel AB-DHP composite film coated glassy carbon electrode (GCE) was fabricated via coating technology. Additionally, the electrochemical behaviors of 2-chlorophenol at bare GCE, DHP-modifed GCE, and AB-DHP modified GCE were investigated, respectively. Compared with the unmodified and DHP-coated GCE, the AB-DHP film-modified GCE significantly enhances the oxidation peak current of 2-chlorophenol, and thus greatly improves its determining sensitivity, suggesting that this new modified electrode has great potential in the determination of trace level of 2-chlorophenol. All the experimental conditions, which affect the electrochemical response of 2-chlorophenol, were studied. Finally, a sensitive and simple voltammetric method with a good linear relationship in the range 2.0 x 10(-7)-4.0 x 10(-5) mol/L, was developed. The detection limit of 2-chlorophenol was 5.0 x 10(-8) mol/L for 2 min accumulation (S/N = 3). This electrode was successfully applied to detect 2-chlorophenol in water samples.

Measurement of cardiac output by open-circuit acetylene uptake: a computer model to quantify error caused by ventilation-perfusion inequality

The ability to assess cardiac output (Q(T)) noninvasively has been the focus of interest for many researchers. While the open-circuit acetylene (C2H2) method seems promising, it is prone to error due to ventilation-perfusion (V/Q) inequality. Measurements during exercise, at high altitude or in patients with chronic obstructive pulmonary disease (COPD) could be unreliable and further validation studies under these circumstances may be needed. We used a computer model based on formulae derived from the multiple inert gas elimination technique to quantify error in Q(T) measurements resulting from V/Q inequality at rest, during exercise or at high altitude. Moreover, potential errors encountered in patients with COPD were quantified. In healthy subjects, V/Q inequality related measurement error seems negligible, under both normoxic and hypoxic conditions and especially during exercise. In COPD, errors up to 20% at rest and up to 15% during exercise are expected. It is therefore concluded from our model that the open-circuit C2H2 uptake method is expected to be accurate in normal subjects. Its validity in COPD needs further study.

Direct determination of total sulfur in wine using a continuum-source atomic-absorption spectrometer and an air-acetylene flame

Determination of sulfur in wine is an important analytical task, particularly with regard to food safety legislation, wine trade, and oenology. Hitherto existing methods for sulfur determination all have specific drawbacks, for example high cost and time consumption, poor precision or selectivity, or matrix effects. In this paper a new method, with low running costs, is introduced for direct, reliable, rapid, and accurate determination of the total sulfur content of wine samples. The method is based on measurement of the molecular absorption of carbon monosulfide (CS) in an ordinary air-acetylene flame by using a high-resolution continuum-source atomic-absorption spectrometer including a novel high-intensity short-arc xenon lamp. First results for total sulfur concentrations in different wine samples were compared with data from comparative ICP-MS measurements. Very good agreement within a few percent was obtained.

Accidental death resulting from acetylene cylinder impact

Acetylene is an inflammable gas commonly used for welding in small-scale industries. We present a case of a 34-year-old male welder who died following injuries sustained from explosion of an acetylene gas-welding cylinder. In this case report, we discuss the circumstances leading to the explosion of the welding cylinder, the autopsy findings, and a brief review of the literature on deaths resulting from blasts of acetylene cylinders.

The Cassini UVIS Stellar Probe of the Titan Atmosphere

The Cassini Ultraviolet Imaging Spectrometer (UVIS) observed the extinction of photons from two stars by the atmosphere of Titan during the Titan flyby. Six species were identified and measured: methane, acetylene, ethylene, ethane, diacetylene, and hydrogen cyanide. The observations cover altitudes from 450 to 1600 kilometers above the surface. A mesopause is inferred from extraction of the temperature structure of methane, located at 615 km with a temperature minimum of 114 kelvin. The asymptotic kinetic temperature at the top of the atmosphere determined from this experiment is 151 kelvin. The higher order hydrocarbons and hydrogen cyanide peak sharply in abundance and are undetectable below altitudes ranging from 750 to 600 km, leaving methane as the only identifiable carbonaceous molecule in this experiment below 600 km.

Antinociceptive properties of acetylenic thiophene and furan derivatives: Evidence for the mechanism of action

The aim of the present study was to evaluate the antinociceptive potential of the acetylenic thiophene and furan derivatives: 3-(furan-2-il) prop-2-yn-1-ol 1, 1-(thiofen-2-il) pent-1yn-3-ol 2 and 4-(thiofen-2-il)-2-metilbut-3-yn-2-ol 3 on three different pain models in mice. The pain models evaluated were the acetic acid-induced writhing, capsaicin-induced pain and the tail immersion test. The possible mechanisms involved in the antinociceptive effect of these compounds were also investigated. Thus, the acetylenic thiophene and furan derivatives presented antinociceptive effect in the pain tests caused by chemical agents. Statistical analysis showed that compounds 1 and 3 increased the latency for tail withdrawal in the tail immersion test (phasic pain). Besides, the role of the opioidergic, muscarinic cholinergic and dopaminergic systems in the acetic acid-induced writhing was examined. The antinociceptive effect of compounds 2 and 3 was prevented by pretreatment with naloxone (1 mg/kg, s.c), but not by atropine (5 mg/kg, s.c) or metoclopramide (1 mg/kg, s.c). Neither naloxone nor metoclopramide prevented the antinociceptive effect caused by compound 1, while the pretreatment with atropine antagonized the antinociceptive action of this compound. The compounds 1-3 used in this study did not reveal any motor impairment to mice in the open field. The results suggest that compounds 2 and 3 induced antinociception in the abdominal writhing test and that their effects are mediated by opiodergic receptors, while the antinociceptive effect of compound 1 may involve muscarinic cholinergic receptors.

[Development of new synthetic method using organometallic complexes and an application toward natural product synthesis]

Recently, many organometallic complexes, such as palladium, nickel, ruthenium, titanium complexes and others, were used for synthetic organic chemistry. We have developed many novel synthetic methods using these organometallic complexes for synthetic organic chemistry. As the organometallic complexes, nickel, chromium, molybdenum, ruthenium, zirconium, titanium, and palladium complexes, were used. Furthermore, bimetallic complexes having silicon-tin and silicon-zirconium bonds were investigated. On the other hand, utilization of gases in synthetic organic chemistry has been also developed. 1 atm pressure of gases such as CO, CO(2), N(2), ethylene and acetylene, could be used and the reaction procedure is very simple, that a balloon filled with a gas is connected on the top of the flask. Using our novel synthetic methods, we have synthesized many natural products and biologically active substances, such as cephalotaxin, mesembrine, tubifoline, strychnine, stemoamide, lycopodine, pumiliotoxin C, beta-lactam, carbapenam and benzodiazepinone derivatives.