Green Conductive Hydrogel Electrolyte with Self-Healing Ability and Temperature Adaptability for Flexible Supercapacitors.

Conductive hydrogels (CHs) are ideal electrolyte materials for the preparation of flexible supercapacitors (FSCs) due to their excellent electrochemical properties, mechanical properties, and deformation restorability. However, most of the reported CHs are prepared by the chemical crosslinking of synthetic polymers and thus usually display the disadvantages of poor self-healing abilities and nonadaptability at environmental temperatures, which greatly limits their application. To overcome these problems, in the present work, we constructed a sodium alginate-borax/gelatin double-network conductive hydrogel (CH) by a dynamic crosslinking between sodium alginate (SA) and borax via borate bonds and hydrogen bonding between amino acids in gelatin and SA chains. The CH displays an excellent elongation of 305.7% and fast self-healing behavior in 60 s. Furthermore, a phase-change material (PCM), Na2SO4·10H2O, was introduced into the CH, which, combined with the nucleation effect of borax, improved the ionic conductivity and temperature adaptability of the CH. The flexible supercapacitor (FSC) assembled with the obtained CH as the electrolyte exhibits a high specific capacitance of 185.3 F·g-1 at a current density of 0.25 A·g-1 and good stability with 84% capacitance retention after 10 000 cycles and excellent temperature tolerance with a resistance variation of 2.11 Ω in the temperature range of -20-60 °C. This green CH shows great application potential as an electrolyte for FSCs, and the preparation method can be potentially expanded to the fabrication of self-repairing FSCs with good temperature adaptabilities.

Preparation of chitosan/sodium alginate conductive hydrogels with high salt contents and their application in flexible supercapacitors.

Conductive hydrogels (CHs) are a potential material for flexible electronics. However, most of CHs display disadvantages of low ionic conductivities and intolerance to low temperatures. Herein, a novel physical CHs with salt contents as high as 30 wt% was prepared with chitosan (CTS) and sodium alginate (SA) by combining the anti-polyelectrolyte effect and semi-dissolution acidification sol-gel transition (SD-A-SGT) method. The obtained hydrogels show extremely high ionic conductivities up to 2.96 × 10-1 S·cm-1 at room temperature and 4.9 × 10-2 S·cm-1 at -20 °C. The effects of different salts on the ion mobility and electrochemical properties of CTS/SA CHs were predicted and analyzed. The flexible supercapacitor assembled using CTS/SA CHs as the electrolyte exhibits the specific capacitance as high as 405 F·g-1 at the current density of 0.25 A·g-1 and satisfying electrochemical stability with 74.91% capacitance retention in 1000 cycles. Our work has provided a new strategy for constructing green CHs with high ionic conductivities.

Early thermal decay of energetic hydrogen- and nitro-free furoxan compounds: the case of DNTF and BTF.

Exploration of the initial reactions of H-free and nitro-free energetic materials could enrich our understanding of the thermal decomposition mechanism of various energetic materials (EMs). In this work, two furoxan compounds, 3,4-dinitrofurazanfuroxan (DNTF) and benzotrifuroxan (BTF), were investigated to shed light on the decay mechanism of furoxan compounds based on the combination of self-consistent charge density functional tight binding and molecular dynamics simulations. The results show that DNTF and BTF decay via a unimolecular mechanism, and the transformation of the furoxan ring into a nitro group is suggested as a novel initial channel. Five initial steps of DNTF thermal decomposition are observed, including NO2 loss and the N(O)-O bond cleavage of the central and peripheral rings. The bond cleavage of peripheral rings dominates the decay at low temperatures, while the central ring opening and C-NO2 dissociation govern the high temperature decay. Besides, NO2, CO and NO fragments are mainly yielded at high temperatures, while CO3N2 is dominant at low temperatures. The three-stage characteristic of the exothermic BTF decay is described under programmed heating conditions for the first time. Four initial steps of BTF thermal decomposition were identified, including furoxan ring opening reactions and the breakage of the 6-membered ring C-C bond. The cleavage of the N(O)-O bond is dominant in the initial step of BTF decomposition under different heating conditions, and the frequency increases with increasing temperature. In addition, the amounts of CON, ON and CO are higher at high temperatures, while C2O2N2 shows an opposite trend. The findings of this work provide deep insights into the complicated sensitivity mechanism of EMs.

Comparative Quantum Chemistry Study on the Unimolecular Decomposition Channels of Pyrazole and Imidazole Energetic Materials.

The difference in the initial decomposition step of pyrazoles and imidazoles was explored using the M062X method for optimization and G4-MP2 and approximated CCSD(T) methods for energies. Laplacian bond order analysis was used to study the effect of the nitro group on the bond strength and predict the bond dissociation energy (BDE) of the ring. Thermochemistry results show that the most possible decay channel of 1H-pyrazole and 3-nitropyrazole is the N2 elimination, while the preferred initial step of 1H-imidazole is the CHN elimination. However, the nitro-nitrite isomerization dominates the decomposition of other nitro derivatives of 1H-pyrazole and 1H-imidazole. As for the formation of HO and HONO, the high energy barrier makes it difficult to take place. Based on the analysis of the lowest energy barrier and the BDE of NO2 loss, it can be concluded that imidazoles are more stable than pyrazoles. This work contributes to revealing the difference in the initial step of energetic isomers and the understanding of the decomposition mechanism of energetic azoles.

Initial Steps and Thermochemistry of Unimolecular Decomposition of Oxadiazole Energetic Materials: Quantum Chemistry Modeling.

In order to resolve the existing discrepancies in the mechanism and key intermediates of oxadiazole thermolysis, the initial decomposition pathways of oxadiazoles have been studied comprehensively using the M062X method for optimization and CBS-QB3 and DLPNO-CCSD(T) methods for energies. The transformation from the furoxan ring to nitro group was suggested as a potential decay channel of furoxan compounds. Results of thermochemistry calculations showed that the preferred decomposition reaction of oxadiazoles is the ring-opening through the cleavage of the O-C or O-N bond. The introduction of the nitro group has little effect on the preferential path of oxadiazole thermal decomposition, but a great impact on the energy barrier. The lowest energy barrier and bond dissociation energy of NO2 loss of azoles were comprehensively studied based on the quantum chemistry calculations. The initial decay steps of 3,4-dinitrofurazanfuroxan and benzotrifuroxan were also studied to give insights into the mechanism of primary stages of thermal decomposition of oxadiazoles.

Preparation of zinc phthalocyanine-loaded amphiphilic phosphonium chitosan nanomicelles for enhancement of photodynamic therapy efficacy.

To increase the solubility and the encapsulation of zinc phthalocyanine (ZnPc) photosensitizer for photodynamic therapy (PDT), a positively charged amphiphilic phosphonium chitosan nanomicelle with multi-benzene structure was developed, and its application to PDT was explored. N-acetyl-l-phenylalanine-(4-carboxybutyl) triphenylphosphonium bromide chitosan (CTPB-CS-NAP), a chitosan derivative with tunable amphiphilicity, was synthesized first. ZnPc was encapsulated in CTPB-CS-NAP at the critical micelle concentration (CMC) of 4.898 mg/L by a hydrophobic self-assembly method to form ZnPc-loaded nanomicelles (ZnPc@CTPB-CS-NAP). The method gives the highest encapsulation efficiency and drug loading of 89.4 % and 22.3 %, respectively. ZnPc@CTPB-CS-NAP is stably dispersed in aqueous solution and shows the average particle size of 103±5 nm. PDT experiments suggest the phototoxicity of ZnPc@CTPB-CS-NAP is much higher than that of ZnPc, but no obvious dark cytotoxicity is observed. Our study has provided a new strategy for improving the photodynamic therapy efficacy of hydrophobic photosensitizer by the encapsulation with chitosan derivative carriers.

Construction of pH/glutathione responsive chitosan nanoparticles by a self-assembly/self-crosslinking method for photodynamic therapy.

A novel pH/glutathione (GSH) multi-responsive chitosan nanoparticles (NPs) material has been successfully designed and prepared by a self-assembly/self-crosslinking method for photodynamic therapy (PDT), which overcomes the shortcomings of traditional photosensitizer carriers, such as poor chemical stability, low loading efficiency and single-responsive photosensitizer release. Amphiphilic sulfhydryl chitosan (SA-CS-NAC) is first prepared by modifying chitosan (CS) with stearic acid (SA) and N-acetyl-L-cysteine (NAC), and then subject to self-assembly and self-crosslinking in the presence of photosensitizer, indocyanine green (ICG), to form the ICG-loaded amphiphilic sulfhydryl chitosan nanoparticles (SA-CS-NAC@ICG NPs). The ICG entrapment efficiency and loading efficiency of the NPs are found to be 95.2% and 27.6%, respectively. The multi-responsive ICG release of the NPs to the low pH and high GSH content of the microenvironment in tumor cells is successfully achieved. Under the laser irradiation, the SA-CS-NAC@ICG NPs produce the amount of reactive oxygen species (ROS) twice of that generated by free ICG under the same conditions. The in vitro cell experiment confirmed the strong cellular uptake ability, low biotoxicity and good tumor inhibition of the NPs. Our work has provided a new strategy for the targeted photosensitizer delivery for PDT.

Dual drug delivery system of photothermal-sensitive carboxymethyl chitosan nanosphere for photothermal-chemotherapy.

Aiming at high drug loading and controlled drug release in chitosan nanocarriers, this work constructed the photothermal sensitive carboxymethyl chitosan nanospheres carrier by introducing controllable heat-sensitive groups into carboxymethyl chitosan molecules. The combination therapy system based on photothermal-chemotherapy was established by virtue of the good photothermal conversion effect of ICG and the high chemotherapy efficiency of DOX. On the one hand, the carrier owned high drug loading and improved the stability of coated-drug. On the other hand, the nanospheres generated photothermal response through NIR irradiation to improve the drug release amount and to achieve the combined treatment effect of photodynamic therapy and chemotherapy. The structures of the nanospheres were fully characterized by Fourier transform infrared (FT-IR), nuclear magnetic resonance (1H NMR) and scanning electron microscope (SEM). In vitro photothermal tests proved that the nanospheres had excellent light stability and photothermal conversion performance. The cytotoxicity test results showed that the nanospheres had no obvious toxicity, but the drug-loaded nanospheres could effectively inhibit the growth of HepG-2 cells via photo-response to release DOX and ICG for achieving photothermal-chemotherapy under NIR irradiation.

Multimolecular Complexes of CL-20 with Nitropyrazole Derivatives: Geometric, Electronic Structure, and Stability.

The multimolecular complexes formed between 2,4,6,8,10,12-hexanitro-2,4,6,6,8,10,12-hexaazaisowurtzitane (CL-20) and nitropyrazole compounds were investigated using B3LYP-D3/6-311G(d,p) and B97-3c methods. CL-20 in these complexes was surrounded by methyl, nitro, and amino derivatives of 4-nitropyrazole. The influence of substituents on the molecular electrostatic potential distribution of nitropyrazoles was investigated to figure out the potential electrostatic interaction sites. For the complex, the O···H hydrogen bond was popular in the intermolecular interactions, and dispersion interaction played an essential role, especially in Cx/CL-20 multimolecular complexes. Trigger bond analysis showed that their strength increased upon the formation of intermolecular weak interactions. Nitro group charge calculations stated that the negative charge on almost all nitro groups showed a significant increase. Therefore, the sensitivity of CL-20 seemed to be lower than the original. In addition, the transfer of electron density between CL-20 and nitropyrzoles in complexes was investigated, revealing the influence of weak interactions on the electron density of CL-20.

Molecular Dynamics Simulations of A27S and K120A Mutated PTP1B Reveals Selective Binding of the Bidentate Inhibitor.

Protein tyrosine phosphatase 1B (PTP1B) is considered a potential target for the treatment of type II diabetes and obesity due to its critical negative role in the insulin signaling pathway. However, improving the selectivity of PTP1B inhibitors over the most closely related T-cell protein tyrosine phosphatase (TCPTP) remains a major challenge for inhibitor development. Lys120 at the active site and Ser27 at the second pTyr binding site are distinct in PTP1B and TCPTP, which may bring differences in binding affinity. To explore the determinant of selective binding of inhibitor, molecular dynamics simulations with binding free energy calculations were performed on K120A and A27S mutated PTP1B, and the internal changes induced by mutations were investigated. Results reveal that the presence of Lys120 induces a conformational change in the WPD-loop and YRD-motif and has a certain effect on the selective binding at the active site. Ser27 weakens the stability of the inhibitor at the second pTyr binding site by altering the orientation of the Arg24 and Arg254 side chains via hydrogen bonds. Further comparison of alanine scanning demonstrates that the reduction in the energy contribution of Arg254 caused by A27S mutation leads to a different inhibitory activity. These observations provide novel insights into the selective binding mechanism of PTP1B inhibitors to TCPTP.

Investigation of selective binding of inhibitors to PTP1B and TCPTP by accelerated molecular dynamics simulations.

Protein tyrosine phosphatase 1B (PTP1B), a key negative regulator in insulin signaling pathways, is regarded as a potential target for the treatment of type II diabetes and obesity. However, the mechanism underlying the selectivity of PTP1B inhibitors against T-cell protein tyrosine phosphatase (TCPTP) remains controversial, which is due to the high similarity between PTP1B and TCPTP sequence and the fact that no ligand-protein complex of TCPTP has been established yet. Here, the accelerated molecular dynamics (aMD) method was used to investigate the structural dynamics of PTP1B and TCPTP that are bound by two chemically similar inhibitors with distinct selectivity. The conformational transitions during the "open" to "close" states of four complexes were captured, and free energy profiles of important residue pairs were analyzed in detail. Additional MM-PBSA calculations confirmed that the binding free energies of final states were consistent with the experimental results, and the energetic contributions of important residues were further investigated by alanine scanning mutagenesis. By comparing the four complexes, the different conformational behavior of WPD-loop, R-loop, and the second pTyr binding site induced by inhibitors were featured and found to be crucial for the selectivity of inhibitors. This study provides new mechanistic insights of specific binding of inhibitors to PTP1B and TCPTP, which can be exploited to the further structural-based inhibitor design. Communicated by Ramaswamy H. Sarma.

Virtual Screening of Novel and Selective Inhibitors of Protein Tyrosine Phosphatase 1B over T-Cell Protein Tyrosine Phosphatase Using a Bidentate Inhibition Strategy.

Protein tyrosine phosphatase 1B (PTP1B), a promising target for type II diabetes, obesity, and cancer therapeutics, plays an important negative role in insulin signaling pathways. However, the lack of selectivity over other PTPs, especially for T-cell protein tyrosine phosphatase (TCPTP), is still a challenge for inhibitor development. Recent studies have suggested that the second phosphotyrosine (pTyr) binding site, close to the catalytic domain, may elevate binding affinity while bringing selectivity to inhibitors. Inspired by these studies, a virtual screening method based on a bidentate strategy was employed to identify novel selective inhibitors of PTP1B. Targeting both the active site and the second pTyr binding site of PTP1B, three compounds (CD00466, JFD02943, JFD02945) were found to be competitive inhibitors ( Ki range from 1.79 to 10.49 µM). The most effective compound, CD00466, exhibited selectivity over TCPTP (31-fold). Using molecular dynamics simulation and the MM/GBSA binding free energy calculation, this study confirmed that the three inhibitors bound to PTP1B in a bidentate pattern. Our work indicates that bidentate virtual screening is a potential approach to the further investigation of selective PTP1B inhibitors.

Initial Mechanisms for the Unimolecular Thermal Decomposition of 2,6-Diamino-3,5-dinitropyrazine-1-oxide.

The initial channels of thermal decomposition mechanism of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) molecule were investigated. The results of quantum chemical calculations revealed four candidates involved in the reaction pathway, including the C⁻NO2 bond homolysis, nitro⁻nitrite rearrangement followed by NO elimination, and H transfer from amino to acyl O and to nitro O with the subsequent OH or HONO elimination, respectively. In view of the further kinetic analysis and ab initio molecular dynamics simulations, the C⁻NO2 bond homolysis was suggested to be the dominant step that triggered the decomposition of LLM-105 at temperatures above 580 K. Below this temperature, two types of H transfer were considered as the primary reactions, which have advantages including lower barrier and high rate compared to the C⁻NO2 bond dissociation. It could be affirmed that these two types of H transfer are reversible processes, which could buffer against external thermal stimulation. Therefore, the excellent thermal stability of LLM-105, that is nearly identical to that of 1,3,5-triamino-2,4,6-trinitrobenzene, can be attributed to the reversibility of H transfers at relatively low temperatures. However, subsequent OH or HONO elimination reactions occur with difficulty because of their slow rates and extra energy barriers. Although nitro⁻nitrite rearrangement is theoretically feasible, its rate constant is too small to be observed. This study facilitates the understanding of the essence of thermal stability and detailed decomposition mechanism of LLM-105.

Self-assembly of mesoporous Bi-S-TiO2 composites for degradation of industrial dinitrotoluene solution under UV light.

Mesoporous Bi-S-TiO2 composites were synthesized by the method combining evaporation-induced self-assembly (EISA) method with impregnation process. Characterization shows mesoporous Bi-S-TiO2 was a highly crystalline anatase, with relatively high thermal stability, large surface area (75-120 m2/g), and large mesopore (10-20 nm). The results also revealed that Bi and S species existed in Bi4+, S2-, S and S6+ forms in the mesoporous TiO2, which allow the mesoporous Bi-S-TiO2 illustrating strong absorption in the ultraviolet region, and the absorption edge shifts to the visible-light region. Photodegradation tests shown that, about 92.3% industrial aqueous dinitrotoluene (DNT) solution could be degraded by 1.5%Bi-S-TiO2 under UV irradiation for 5 h. Concentration of Bi ions and calcination temperature were found to play important roles in its mesoporous properties and photocatalytic activity.

Preparation of H3PW12O40/MCM-48 and its photocatalytic degradation of pesticides.

A composite catalyst H3PW12O40/MCM-48 was prepared by loading photocatalyst phosphotungstic acid H3PW12O40 (HPW) to molecular sieve MCM-48 by impregnation method, and its structure was characterized by Fourier transform infrared (FT-IR) spectra, small angle X-ray diffraction (XRD) patterns, nitrogen adsorption analysis and High-resolution transmission electron microscopy (HRTEM) analysis. Photocatalytic degradation activities of HPW/MCM-48 against pesticides imidacloprid and paraquat were evaluated under UV radiation (365 nm). The results show that HPW/MCM-48 maintains the mesoprous molecular sieve structure of MCM-48 and the Keggin structure of HPW, while the BET surface area is 793.35 m2 x g(-1), pore volume is 1.46 cm3 x g(-1), average pore diameter is 2.76 nm, suggesting loading HPW on MCM-48 is a considerable way to improve its surface area. After 14 h UV irradiation (365 nm), 57.38% imidacloprid and 63.79% paraquat were degraded by 20 mg HPW/MCM-48 catalyst, while HPW and blank group degraded the two pesticides at the degradation rate of about 25% and 5%, respectively. Implying loading on MCM-48 could greaterly improve the degradation activity of HPW. The reslut of degradation kinetics show that, the degradation process of HPW/MCM-48 fits first order kinetics equation. The rate constant Ka of HPW/MCM-48 toward imidacloprid and paraquat are 0.089 h and 0.117 h, with the half-life t(1/2) of 7.8 h and 5.9 h, respectively.

Photocatalytic degradation of imidacloprid by composite catalysts H3PW12O40/La-N-TiO2 under visible light.

Catalysts H3PW12O40/La-N-TiO2 were prepared and characterized by FT-IR, N2 adsorption-desorption analysis, SEM and UV-Vis diffuse reflection spectrum (DRS). It was demonstrated that Keggin structure of H3PW12O40 retained in composite materials by the FT-IR test; After doping La-N, the BET surface area of them is nearly 2 times as that of pure TiO2; the SEM images of the catalysts revealed that they were consist of relatively uniform spherical grains with good dispersion; UV-Vis DRS showed the photoresponse performance of the prepared composites for the visible light area were improved after doping La and N. The prepared composites were used as photocatalysts in degradation of pesticide imidacloprid. Results revealed that 30%H3 PW12O40/0.3%La-1.0%N-TiO2 possessed the best photocatalytic activity under visible light above 400 nm. Thus, imidacloprid were degraded 91.57% after 3 h irradiation. When 30% H3PW12O40/0.3%La-1.0%N-TiO2 was used as catalysts, degradation ration could even reach 98.89% after 6 h.

Experimental and numerical study of the dispersion of carbon dioxide plume.

Carbon Capture and Storage (CCS) and Enhanced Oil Recovery (EOR) technologies have been widely applied in the environmental protection and petroleum production fields. However, accidental release of carbon dioxide may cause damage and losses during oil and gas production. This paper presents a reduced-scale field experiment designed to imitate a CO2 blowout for the purpose of acquiring concentration the distribution in the flow field. Additionally, computational fluid dynamics (CFD) code was used to perform numerical simulations of the field experiment using the k-ε, RNG k-ε and SST k-ω models. The results of these models were compared with the experimental data for validation, and statistical performance indicators were introduced to verify the simulated values. According to experimental and numerical results, the interior flow structure of a CO2 plume was analyzed together with consideration of negative buoyancy effects. The concentration as a function of time was studied by comparing the observed values and simulation results. We conclude that the CFD simulation results from the k-ε and SST k-ω models are in acceptable agreement with the experimental data according to the Chang's criteria, and predicted values from the RNG k-ε model are unsatisfactory. Therefore, the CFD techniques can be satisfactorily applied in industrial risk analysis procedures with acceptable accuracy according to the Chang's criteria.

[Preparation, characterization and photocatalytic activities of polyoxometalates immobilized on mesoporous moleculer sieve].

Heterogeneous photocatalysts consisting of phosphotungstic acid or silicotungstic acid immolilized on mesoporous molecular sieve MCM-41 were prepared and characterized by FTIR, X-ray diffraction, nitrogen adsorption and high resolution transmission electron microscope (HRTEM). The photocatalytic activities of the prepared H3PW12 O40/MCM-41 or H4SiW12O40/MCM-41 were examined by photodegradation of pesticide paraquat. Results show that the prepared composites have large specific surface area and uniform mesopores, the Keggin structure of two parent heteropoly acids was retained after loading on MCM-41. Both of the prepared photocatalysts exhibit high activityies under irradiation of 365 nm monochromatic Light. For 50 mL paraquat (10 mg x L(-1)), conversions of paraquat using 15 mg H3PW12O40/MCM-41 or H4SiW12O40/MCM-41 as catalysts after 14 hours' irradiation are 92.0% and 87.6% respectively. The photocatalytic reactions are in accordance with the first order kinetics equation, and the half lives of the reactions are 3.6 h and 4.7 h respectively.

[FTIR spectroscopic study on synthesis and adsorption performance of amino phosphonic acid chelating fiber].

During the preparation of amino phosphoric chelating fiber, polypropylene grafted styrene, acetyl, amine series and amino phosphonic acid chelating fibers were certified by infrared spectrum, and the functionalization degree of raw fibers was studied. By the semi-qualitative method of infrared spectrum, the adsorption performance of indium and copper on amino phosphonic chelating fiber was also discussed. The results showed that (1) The peak at 1 116 cm(-1) was assigned to--P(ONa)2 in amino phosphonic acid chelating fiber. So the success of phosphorylation was verified. (2) During preparation, the phosphorylation effect of amino phosphonic acid chelating fiber could be reflected by the change of the peaks at 1 056 and 1 110 cm(-)1. (3) After adsorption of In3+ on amino phosphonic acid chelating fiber, the new forming N-In coordination key was absorbed strongly at the bands of 1 000-1 200 cm(-1) and at 1 107, 699 and 617 cm(-1). After adsorption Cu2+ on amino phosphonic acid chelating fiber two new strong and wide peaks were found at 1 110 and 618 cm(-1), respectively. (4) Through the area change of the bands at 1 200-900 and 600 cm(-1), the adsorption performance of indium and copper on amino phosphonic acid chelating fiber was compared.

Anti-HepG-2 cell properties of rare earth tungstosilicic polyoxometalates containing 5-fluorouracil.

Two novel rare earth tungstosilicic polyoxometalate containing 5-fluorouracil, K26 (C4 H4 FN2O2)8Pr (SiW11 O39)4 x 10H2O (FPSW) and K26(C4H4FN2O2)8Sm(SiW11O39)4 x 9H2O (FSSW), were synthesized and their structure were characterized by using elemental analysis, FTIR spectra, X-ray powder diffraction and TG. The antitumor activity tests of the compounds FPSW and FSSW were carried out by the methyl thiazolyl tetrazolium method in hepatocellular carcinoma cell HepG-2. The results showed that FPSW and FSSW could inhibit the HepG-2 cells in vitro significantly. The EC50 of FPSW and FSSW is 1.94 x 10(-5) and 1.32 x 10(-5) mol x L(-1) respectively. The therapeutic index of FPSW and FSSW is 0.76 and 1.58 respectively.