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Fast pyrolysis of the mixed plastics (PE: PP: PS: PVC = 0.5: 0.3: 0.15: 0.05) with and without hydrothermal dechlorination pretreatment were investigated in a fixed bed reactor to determine the effects of pyrolysis parameters (temperature, carrier gas flow rate and particle size) on the distribution and the quality of the products. The results showed that high pyrolysis temperature, high carrier gas flow rate and small particle size promoted the migration of organic chlorine in condensable products to inorganic chlorine in gas products. And the optimal conditions for fast pyrolysis of mixed plastics to produce oil were the pyrolysis temperature of 500 °C, carrier gas flow rate of 40 ml/min and particle size of 0.1–0.15 mm with the maximum oil yield of 67.88 wt%. Hydrothermal pretreatment of mixed plastics has shown an excellent dechlorination efficiency of 99.9 %. Furthermore, the total yield of oil and wax was increased by 7.06 wt%, meanwhile the content of C5-C9 components in the pyrolysis oil showed an upward trend when compared with fast pyrolysis without pretreatment. Besides, the concentration of methane achieved 50.68 % due to the possible weakening effect of hydrothermal pretreatment on C C bond energy of β-position.

Levoglucosan is served as a significant versatile product to generate high value-added chemicals and pharmaceutical additives. Levoglucosan was predominately produced from pyrolysate of cellulose. However, the direct fast pyrolysis of waste biomass produces a small quantity of levoglucosan in comparison with the theoretical value of cellulose. This study explored Fenton pretreatment as a possible route to enhance levoglucosan yield during the fast pyrolysis of the waste corncob. The experimental results showed that different Fenton pretreated conditions and pyrolytic temperatures played vital roles in the formation of levoglucosan. The levoglucosan yield from fast pyrolysis at 500 °C of corncob pretreated by Fenton reaction of 14 mL/g H2O2 and 16 mM FeSO4 was about 95% higher than that of the untreated corncob. Additionally, Fenton pretreated corncob was capable of obtaining the levoglucosan at a low pyrolytic temperature (300 °C). It was mainly attributed to the effective disrupting of biomass structures and the selective degradation of lignin and hemicellulose during pretreatment. Furthermore, the powerful removal of alkali and alkaline earth metals during Fenton pretreatment was beneficial to increasing the levoglucosan yield. These findings demonstrate that Fenton pretreatment can provide a novel effective method to enhance levoglucosan yield during biomass fast pyrolysis.

Biogas slurry, a byproduct of biogas plants, is considered a high-quality bio-organic fertilizer. Despite providing nutrients to crops, biogas slurry may contain a high concentration of heavy metals, leading to food safety problems and endangering human health if such metals are absorbed by plants. Therefore, biogas slurry should undergo systematic risk assessment prior to direct use on farmland to ensure its safety for soils and crops. In this study, the risk of applying biogas slurry in peanut cultivation was comprehensively evaluated. Based on nitrogen contents, different concentrations of biogas slurry were applied in peanut cultivation. The results achieved herein showed that the application of biogas slurry as a nutrient supplier in peanut cultivation would significantly affect the physical and chemical properties of soil and characteristics of the plant and the quality of peanuts. Although the heavy metal content of biogas slurry was within the permitted range, it had potential risks to human health and the environment. Principal component analysis (PCA) showed that biogas slurry was the primary source of heavy metals in soil. After the application of biogas slurry, the contents of As and Hg in the soil increased significantly, which were 11.12 and 26.67 times higher than those in the control soil. The contents of Cu, Zn, Pb, Cd, and As in peanut kernel samples under different levels of biogas slurry application were all lower than the maximum permissible limit set by the Standardization Administration of China. In contrast, the content of Hg in peanut kernels was higher than the maximum permissible limit value of 0.02 mg/kg. Peanut had a higher enrichment capacity of Cd and Zn and a higher migration capacity of Pb. The health risk assessment showed that the long-term consumption of peanuts grown with a high dosage of biogas slurry would be harmful to the health of children aged 2–6 years with a large consumption level.

Micro electrical discharge machining (micro EDM) is able to remove conductive material by non-contact instantaneous high temperature, which is more suitable for machining titanium and its alloys compared with traditional machining methods. To further improve the machining efficiency and machined surface quality of micro EDM, the nano particle surfactant mixed micro EDM method is put forward in this paper. Experiments were conducted to explore the effect of nano particle surfactant on the micro EDM performance of titanium alloy. The results show that the material removal rate of micro EDM in dielectric mixed with TiO2 is the highest when open-circuit voltage is 100 V, followed by Al2O3 and ZrO2. Lower tool wear rate can be produced by using dielectric mixed with nano particle surfactant. The taper ratio of micro EDM in dielectric mixed with nano particle surfactant is higher than that in deionized water. The surface roughness Ra of micro EDM in dielectric mixed with TiO2 can be 50% lower than that in deionized water. It is helpful to improve the machining performance by adding surface surfactant in the dielectric of micro EDM.

Single-component and competitive adsorption of tetracycline (TC) and Zn(II) on an NH4Cl-induced magnetic ultra-fine buckwheat peel powder biochar (NH4Cl-BHP-char/Fe3O4) was investigated in batch experiments. NH4Cl-BHP-char/Fe3O4 exhibited a large surface area of 1119.097 m2 g−1 and a total pore volume of 0.139 cm3 g−1 and was easily separated from aqueous solution using a magnet. Also, adsorption was endothermic, spontaneous, and highly pH-dependent. The optimum pH of the single-component adsorption of TC and Zn(II) was 4.0 and 6.5, respectively, and the optimum pH of co-adsorption was 6.0. The kinetics studies showed the prepared biochar could be rapidly adsorbed within 60 min, and chemical adsorption was dominant. For single-component adsorption, the maximum adsorption capacities of TC and Zn(II) were 106.38 and 151.52 mg g−1, respectively, and they underwent monolayer adsorption on the biochar surface. Moreover, for competitive adsorption, maximum TC and Zn(II) adsorption capacities of 126.58 and 357.14 mg g−1 were achieved. Both film diffusion and intra-particle diffusion were found to be significant processes to facilitate adsorption. TC and Zn(II) promoted the adsorption of each other. The proposed biochar could be used repeatedly for at least four cycles. All these results demonstrated that developed NH4Cl-BHP-char/Fe3O4 was regarded as a low-cost alternative adsorbent to remove the heavy metal ions and antibiotic pollutants from water or wastewater.

The electrocatalytic activity of hematite with different exposed facets toward the oxygen evolution reaction (OER) was investigated. Hematite nanoparticles with pseudo cubic, hexagonal bipyramid and plate morphologies were prepared, which predominantly have exposed (012), (113) and (001) facets, respectively. The OER activity of hematite measured under alkaline conditions was significantly dependent on the surface orientation, and the onset potential of the (001) facet was more than 130 mV more negative than those of the (012) and (113) facets. On the basis of the results of spectroelectrochemical measurements and theoretical calculations, this higher activity of the (001) facet was attributed to the lower energy required for the formation of oxo intermediate species. When pH conditions changed from alkaline to neutral, the facet dependence was less pronounced and the OER initiated from almost the same potential on all of the three facets. These findings indicate that the factor determining the OER activity of hematite differs depending on pH, and the surface structure strongly affects the OER activity under conditions where the concerted transfer of protons and electrons proceeds.

Biochar conversion from corn stover was evaluated under various process conditions, and the absorption capacity of biochar was investigated for the removal of oxytetracycline in wastewater. Biochar was prepared at lower carbonization temperatures (200–500 °C) and was used in three different concentrations of chemical oxygen wastewater. The results showed that the biochar prepared at the temperature range of 200–500 °C had a faster sorption rate and shorter sorption equilibrium time compared to biochar produced at higher temperatures. The longest time to reach sorption equilibrium was 9 h for biochar obtained at 200 °C. However, the biochar prepared at 500 °C required only 0.5 h to reach the sorption equilibrium. The corn stover-biochar had the highest sorption capacity of 246.3 mg/g for oxytetracycline at 30 °C. The adsorption kinetics was consistent with pseudo–second-order kinetics. This study provides a theoretical basis for the conversion of corn stover into biochar as efficient sorbents.

Fenton reaction has been widely used for pretreatment of lignocellulose with the advantages of simple operation, a rapid reaction rate, and less pollution. In this study, batch and fed-batch Fenton...

A photonic quasi-crystal fiber (PQF) with high birefringence based on ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) is described. There are two elliptical air holes in the core to increase birefringence and the outer air hole array has a twelve-fold Stampfli-type quasi-crystal structure. ZBLAN reduces absorption loss in the infrared region resulting in higher birefringence. The birefringence and confinement loss of the PQF are analyzed numerically by the full-vector finite element method. Birefringence is higher than that of conventional polarization-maintaining fibers due to the two elliptical air holes in the center and reaches the maximum of 4.15×10−2 at a wavelength of 2 μm. The novel structure has great potential in high-performance optical devices.

A new inorganic-organic hybrid solid, namely, Zn2(dmen)3B10O14(OH)6 (dmen = N, N′-dimethylethylenediamine) was prepared under solvothermal conditions. This compound has a molecular structure with B5O7(OH)3 clusters bridged and decorated by zinc–amine complexes. It is a direct-gap material with a band gap of 5.21 eV. The band structure and density of states of the compound were also calculated based on density functional theory.

In this paper, a new surface modification method was reported for the preparation of Phyllostachys pubescens powder as an effective adsorbent for the removal of chromium. Complex copper sulfide (Cu-S)nanospheres were evenly dispersed and loaded into the internal surface of the adsorbent, which provided both the ion exchange and oxidative-reductive properties. The composite showed an excellent adsorption efficacy for Cr(III) and Cr(VI). The surface properties of the obtained materials were characterized by FTIR and SEM. Maximum adsorption for Cr(III) and Cr(VI) was observed at pH 6.1 and 1.9, respectively. The experimental sorption equilibrium data were modeled using Langmuir and Freundlich isotherm equations. It was found that the maximum adsorption capacities of Cr(III) and Cr(VI) were 52.30 mg g-1 and 94.25 mg g-1, respectively. The adsorption mechanism analysis inferred that the major adsorption mode of Cr(III) was ion exchange, and Cr(VI) was oxide-reduction.

A novel method for preparing porous carbon materials from biomass pyrolysis vapors with calcium citrate template has been proposed. The effects of pyrolysis temperature, pyrolysis heating rate and carbon-containing precursor preparation temperature on the yield of biomass pyrolysis products, composition of light bio-oil and structure of porous carbons were investigated. The physicochemical characterization and hydrogen adsorption experiments were carried out for the prepared porous carbons. The carbonization mechanism of the carbon-containing precursor was studied and a five-stage reaction kinetic model was established by Gaussian peak separation method according to the DTG curves. Under the optimal conditions of pyrolysis temperature (823 K), heating rate (10 K/min) and carbon-containing precursor preparation temperature (473 K), the prepared porous carbon material has the largest specific surface area of 1703 m2/g, relatively high micropore volume of 0.51 cm3/g and microporosity of 24.17%. The hydrogen adsorption capacity of the carbon material can reach 170.12 cm3/g (1.53 wt%) at 77 K at atmospheric pressure. This paper provides a novel and environmental-friendly method for the preparation of porous carbon materials, and also presents a new way for the utilization of biomass pyrolysis vapors before condensation.

Biomass waste pyrolysis has taken an increasing interest in producing biofuels and bio-based chemicals, but the complex compositions of pyrolytic liquid hinder its development and utilization. To address these challenges and improve the yield of target chemicals (levoglucosan) and aromatics, a novel two-stage process based on NaOH-Fenton pretreatment coupled with fast pyrolysis is firstly proposed. Firstly, rice straw was pretreated by dilute alkali to separate lignin fractions, and then the residue was further treated via Fenton reaction at room temperature to obtain cellulose-rich substrate. The fast pyrolysis of raw rice straw produced the complex compositions in the pyrolytic liquid. After NaOH-Fenton pretreatment, the target platform chemicals in the pyrolysate were effectively concentrated. The cellulose-rich substrate exhibited a very high absolute yield of levoglucosan (201.9 mg/g) as compared to raw rice straw (not detected). The lignin fractions recovered from this process were catalytically fast pyrolyzed for preparing aromatic fuels. Furtherly, the maximum removal rates of nitrogen (76.5%) and sulfur (93.3%) were achieved by the coupled process. A short-chain cellulose-rich substrate with similar dissociation energy of glycosidic bonds was formed by the NaOH-Fenton process based on the analytical results of the DFT calculation and mechanism. The similar dissociation energy of C–O bonds from the short-chain cellulose-rich substrate favors the formation of high-yield levoglucosan in subsequent fast pyrolysis. This work introduces a simple and highly efficient strategy to convert grass biowaste into value-added chemicals and liquid fuels.

A promising UV nonlinear optical material, beryllium-free nitrate Ba2NO3(OH)3, has been synthesized via modified high-temperature solid state reactions in a self-made high-pressure apparatus which exhibits a perfect balance of a large second harmonic generation coefficient, an appropriate birefringence for phase matching, a short UV absorption cutoff edge and physicochemical stabilities.

A novel CeO2-MoO3-WO3/TiO2 (CMWT) catalyst was prepared by a single step sol-gel (SG) method. It exhibited 93.8%–98.9% of NO conversion at 275–450 °C and high tolerance to 10% H2O and 1000 ppm SO2 at a gas hourly space velocity (GHSV) of 90,000 h− 1. Superior SCR activity of CMWT catalyst could be attributed to the presence of more Ce3 + and chemisorbed oxygen, higher redox ability, stronger adsorption capacity of NH3 species and the strong interaction among ceria, molybdenum, tungsten and titania.

In this paper, chemical precipitation process is used for the treatment of the desulfurization wastewater generated by the waste gas treatment system of the limestone-gypsum flue gas desulfurization process of a thermal power plant. After one year of operation, the technology is reliable and stable. The removal rate of suspended matter, COD, fluoride, mercury and sulfate reached 99.5%, 98.3%, 87.5%, 99.8% and 85.6% respectively, and the corresponding effluent concentrations were 54 mg/L, 20 mg/L and 9.6 mg/L, 0.04 mg/L, 980 mg/L. Finally, the effluent quality of the system is better than the discharge requirements of “Discharge standard of wastewater from limestone-gypsum flue gas desulfurization system in fossil fuel power plants” (DL/T997-2006). In addition, the total electricity and chemical charges per ton of wastewater treatment were 6.50 yuan, which is lower than most of the engineering project under the same discharge requirements. Therefore, the process has certain engineering advantages.

As a novel catalyst for oxygen reduction reaction (ORR), nitrogen-doped carbon xerogel was prepared via a sol-gel followed by the subsequent pyrolysis in ammonia atmosphere and post-treatment process. The resultant catalysts were characterized by BrunauereEmmetteTeller (BET), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) analysis and electrochemical measurements. The role of metal in the catalyst was studied by comparing catalytic activities of the catalysts with and without post-treatment. Results show that the catalyst with nitrogen doped on the surface possesses an amorphous microstructure. The catalysts with and without post-treatment showed almost the same ORR electrocatalytic activities, which clearly demonstrated the negligible influence of metal removal on ORR performance. The catalyst with post-treatment displayed comparable ORR activity to that of Pt/C in alkaline medium as well as superior stability. A maximum power density of 115 mW cm −2 at 40 °C was achieved on the single cell with the as-prepared catalyst as cathode, demonstrating its application as promising alternative for Pt-based electrocatalysts in direct borohydride fuel cells.

This study aims to report on the feasibility of enhancing light olefins production from ex-situ catalytic fast pyrolysis (CFP) of biomass by co-feeding with steam and determine the role of steam. Effects of steam on catalyst and pyrolysis/catalysis reactions in ex-situ CFP were investigated using a two-stage fluidized-bed/fixed-bed reactor. Carbon yield of olefins + monocyclic aromatic hydrocarbons (MAHs) increased by 23.80% after proper steam dealumination of HZSM-5 framework, which suggests that HZSM-5 can be activated at the initial exposure to steam. For activated HZSM-5, olefins carbon yield increased by 35.65% and olefins to MAHs (O/M) ratio boosted from 0.83 to 1.60 as steam concentration in carrier gas increased from 0% to 40%, while the total carbon yield of olefins and MAHs still kept at the same level. Steam enhanced olefins production by: (1) promoting the formation of light compounds in bio-oil, which are the main precursors of hydrocarbons, during pyrolysis; (2) inhibiting aromatization reactions during catalysis. It provides a possibility for the control of O/M ratio of hydrocarbon products and the enhancement of light olefins production from CFP of biomass.

A high-birefringence(HB) photonic quasi-crystal fiber(PQF) with all-circular air holes is designed and ZrF4-BaF2-LaF3-AlF3-NaF(ZBLAN) is used to increase the birefringence and reduce confinement loss of the PQF in the infrared region. The structure of the PQF is analyzed and optimized numerically using the full-vector finite element method by adopting the perfectly matched layer boundary conditions. The PQF possesses higher birefringence in the wavelength range between 1.3 and 1.8μm and the maximum birefringence value of 4.1×10−2 is achieved at 1.55μm. This is the highest birefringence value reported from all-circular-hole PQFs so far suggesting that the novel structure has great potential in high-performance optical devices.

The aim of the present study was to investigate the effects of bradykinin (BK) on an epithelial-mesenchymal transition (EMT) model in retinal pigment epithelium (RPE) cells through exposure to transforming growth factor-β1 (TGF-β1). The aim was to improve the effect of BK on proliferative vitreoretinopathy (PVR) progression, and to find a novel method of clinical prevention and treatment for PVR. The morphology of ARPE-19 cells was observed using an inverted phase-contrast microscope. A Cell Counting Kit-8 was used to assess the effects of TGF-β1 on the proliferation of ARPE-19 cells. Western blotting and immunofluorescence were used to detect the expression levels of the epithelial marker E-cadherin, mesenchymal markers α-smooth muscle actin (SMA) and vimentin, and phosphorylated (p) mothers against decapentaplegic homolog (Smad)3 and Smad7 of the TGF/Smad signaling pathway. Wound healing tests and Transwell assays were performed to detect cell migration ability. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis was performed to detect the expression levels of pSmad3 and Smad7 in the TGF/Smad signaling pathway. The results revealed that the addition of 10 ng/ml TGF-β1 resulted in the expression of factors associated with EMT in ARPE-19 cells. BK decreased the expression levels of the mesenchymal markers α-SMA and vimentin, and increased the expression of the epithelial marker E-cadherin. BK decreased cell migration in TGF-β1-induced EMT. These effects were reversed by HOE-140, a specific BK 2 receptor antagonist. BK significantly downregulated the expression of pSmad3 and upregulated the expression of Smad7 in TGF-β1-treated ARPE-19 cells, and the protective alterations produced by BK were inhibited by HOE-140. In conclusion, 10 ng/ml TGF-β1 resulted in EMT in ARPE-19 cells and BK served a negative role in TGF-β1-induced EMT. BK had effects in TGF-β1-induced EMT by upregulating the expression of Smad7 and downregulating the expression of pSmad3 in TGF-β/Smad signaling pathway, indicating that BK may be a novel and effective therapy for PVR.

A MoO 3 modified CeO 2 /TiO 2 catalyst was prepared by a single step sol–gel method for selective catalytic reduction of NO with NH 3 . The experimental results indicates that MoO 3 modified CeO 2 /TiO 2 catalyst exhibited higher SCR activity and resistance to 10% H 2 O and 1000 ppm SO 2 . From the characterization results, it can be concluded that good physical properties, highly dispersed active species of Ce and Mo, more appearance of Ce 3+ and chemisorbed oxygen, strong interaction among ceria, molybdenum and titania, and high oxygen storage capacity might contribute to the excellent deNO x performance of CeO 2 –MoO 3 /TiO 2 catalyst prepared by a single step sol–gel method.

A Ce–W–Ti mixed oxide catalyst prepared by a single step sol–gel method exhibited excellent SCR activity and high resistance to H2O and SO2. The excellent catalytic performance might be attributed to the improved dispersion of Ce species on TiO2, the increase in the amount of Ce3+ and chemisorbed oxygen and the strong interaction among ceria, tungsten and titania owing to the addition of WO3.

Two biosorbents were prepared using bamboo powder modified with mercaptoacetic acid and carbon disulfide, which exhibits strong adsorption properties for Cu2+ and Ni2+. The obtained materials were characterized by FTIR. Maximum adsorption for both metals was found to occur around pH 5.0–6.5. The kinetic data followed the pseudo-second-order model. The maximum adsorption capacities of Cu2+ and Ni2+ on mercaptoacetic acid modified bamboo powder determined from Langmuir isotherm were 103.97mg g−1 and 61.35mg g−1, respectively. While on carbon disulfide modified bamboo powder were 128.21mg g−1 and 56.82mg g−1, respectively. The adsorption mechanism analysis revealed that the most possible adsorption mode of Cu2+ was coordination, and Ni2+ was ion exchange. The obtained adsorbents could effectively remove Cu2+ and Ni2+ from industrial electroplating wastewater and could be used repeatedly for more than five cycles.

Chemical looping co-gasification of pine wood and polyethylene with CaO/Fe2O3 oxygen carrier was preliminarily conducted in a fixed bed reactor and thermogravimetric analyzer (TGA). The effects of Fe2O3 /biomass mass ratio, temperature and steam/biomass mass ratio on the product distribution (syngas yield, H2/CO ratio and cold gas efficiency) during the pine wood chemical looping gasification were investigated. Results showed that the optimal product distribution was obtained at the gasification temperature of 850 °C with the Fe2O3/feedstock ratio of 0.25 and steam/biomass mass ratio of 0.25. The interactions of pine wood and polyethylene were further studied. It was found that the positive or even the synergetic effects existed, which resulted in the enhancement of syngas and hydrogen yield. The optimal addition of 75% polyethylene increased H2 yield from 0.62 Nm3/kg to 1.59 Nm3/kg compared to the pine wood chemical looping mono-gasification. Chemical looping co-gasification also improved the cold gas efficiency from 77.22% to 89.30% and H2/CO ratio from 1.54 to 1.88. The CaO/Fe2O3 mass ratio of 1.0 was sufficient to elevate the H2/CO ratio above 2. The maximum H2 yield of 1.73 Nm3/kg, cold gas efficiency of 92.23% and H2/CO ratio of 2.09 were finally obtained to meet the demand for the Fischer-Tropsch synthesis. The presence of synergetic effects on syngas and hydrogen yield from the fixed bed data but their absence from the TGA data revealed the interaction mechanism could be attributed to gas phase reformation and cracking reactions.

Methylene blue (MB) can ameliorate behavioral, neurochemical, and neuropathological impairments in animal models of acute and chronic neurodegenerative disorders, but the underlying mechanism remains unclear. Myocyte enhancer factor 2 (MEF2D) is known to promote neuronal survival in several models, and several survival and death signals converge on MEF2D and regulate its activity. Here, we investigated the role of MEF2D in the neuroprotective effect of MB against glutamate-induced toxicity in HT22 neuronal cells. Our results showed that MB, event at less than 100 nM, improved the viability of HT22 cells exposed to 2 mM glutamate. MB attenuated the mitochondrial impairment and quenches the reactive oxygen species (ROS) induced by glutamate. Surprisingly, MB at 50–200 nM did not affect the Nrf2/HO-1 pathway, an important endogenous anti-oxidative system. Further study showed that MB increased the transcription and translation of MEF2D. In addition, MB upregulated the expression of mitochondrial NADH dehydrogenase 6 (ND6) in a MEF2D-dependent manner. Knockdown of MEF2D abolished both MB-medicated increase of ND6 and MB-induced neuroprotection against glutamate-induced toxicity. Moreover, we showed that MB promoted Akt function activity, suppressed GSK-3β activity, and increased MEF2D level in hippocampus of mice and HT22 cells. These findings for the first time demonstrate that MB protects HT22 neuronal cells against glutamate-induced cell death partially via the regulation of MEF2D-associated survival pathway.

S-adenosylhomocysteine (AdoHcy) hydrolase is an enzyme that regulates biomethylation and some other physiological processes. Recombinant AdoHcy hydrolase was overexpressed inE. coli JM109 and purified with ion exchange and gel filtration chromatographies. The effects of copper ions (Cu2+) on the activity of AdoHcy hydrolase were investigated and the results showed that Cu2+ inhibited the enzyme’s activity by a concentration and time-dependent process. The inhibition constant (Ki) and the apparent rate constant (kapp) were calculated to be (14 ±4) nmol · L−1 and (1.08 ±0.15) min−1, respectively. The existence of the natural substrate Ado could to some extent prevent Cu2+ from inactivating the enzyme, suggesting that copper ions possibly could compete with the natural substrate on enzyme’s substrate binding site. Further studies on the mechanism of inhibition are being carried out.