Liquid-phase Method Research Articles

Flocculation synergistic with nano zero-valent iron augmented attapulgite @ chitosan as Fenton-like catalyst for the treatment of landfill leachate

ABSTRACT In this study, nano-zero-valent iron (NZVI) was added to attapulgite/chitosan and used as a catalyst in the heterogeneous Fenton process to degrade stabilized landfill leachate. Landfill leachate has serious environmental impacts due to the complexity and diversity of its pollutants. A magnetic catalyst (NZVI@PATP/CS) was prepared by a liquid-phase reduction method. The NZVI@PATP/CS were characterized by XRD, FTIR and SEM. The pH of leachate and the dosage of catalyst and H2O2 were changed to determine the best-operating conditions for the effective removal of chemical oxygen demand (COD) and total phosphorus(TP). To understand the adsorption degradation mechanism, the quenching experiments of free radicals were carried out. The results showed that the degradation rates of COD and TP were 66% and 92%, respectively, under the optimum pH value of 8, the dosage of H2O2 of 5 mL, and the dosage of the catalyst of 0.25 g for 60 min.

Effects of Mn, Zr and Ni Promoters on the Performance of CuZnO Catalyst for Ethanol Synthesis via CO Hydrogenation

A series of CuZnO catalysts modified with Mn, Zr and Ni promoters were prepared by the complete liquid-phase method. The results show that modification of Mn and Zr can effectively improve the CO conversion and reduce the generation of hydrocarbons. The carbon chain growth ability of catalyst was enhanced by Ni modification. Under the reaction conditions of 4 MPa and 280 °C, the ethanol selectivity reached 17.7 % in the 2 %Ni modified catalyst.

Two microfluidic chips based on Rayleigh surface acoustic waves for controllable synthesis of silver nanoparticles: A comparison

Based on the biocompatibility and non-invasive nature of acoustically driven microfluidics, two microfluidic chips with Rayleigh surface acoustic waves (SAWs) as the driving source are proposed for micro-scale mixing: traveling surface acoustic wave (TSAW) and standing surface acoustic wave (SSAW) chips. This paper presents the first comparison of the controllable synthesis of silver nanoparticles (AgNPs) by TSAW chip and SSAW chip. The effect of peak-to-peak voltage and inlet flow rate on the micro-mixing performance of the two chips is investigated in focus. First, based on the finite element theory, the simulation software COMSOL is used to compare and analyze the mixing performance of the two chips. Then, a series of experiments of AgNPs synthesis is carried out combining with the liquid-phase reduction method. The difference in the results is characterized by UV spectroscopy and transmission electron microscope (TEM). The simulation results reveal that, under the same conditions, the SSAW chip transmits more energy to the fluid, which can effectively disturb the fluid and destroy the laminar flow interface. That is, it is easier to achieve rapid and uniform mixing with a better micro-mixing effect. As the peak-to-peak voltage increases or the inlet flow rate relatively decreases, the mixing effect of the SSAW chip gradually becomes better. However, experimental results indicate that the TSAW chip can synthesize AgNPs with higher concentration, better monodispersity, and smaller size deviation. As the peak-to-peak voltage increases or the inlet flow rate relatively decreases, it is easier to synthesize AgNPs with better quality. The comparison of the simulation and experimental results of the two chips can provide guidelines for the analysis of micro-scale mixing performance and practical applications of microfluidic chips driven by SAWs.

Mechanism-Enhanced Active Attapulgite-Supported Nanoscale Zero-Valent Iron for Efficient Removal of Pb2+ from Aqueous Solution.

In this study, attapulgite-supported nano zero-valent iron (nZVI@ATP) was synthesized by a liquid-phase reduction method using active attapulgite (ATP) as raw material, and used for Pb2+ remediation in aqueous solution. To understand the mechanism of Pb2+ removal, various techniques were used to characterize nZVI@ATP. The results showed that spherical nZVI particles were uniformly dispersed on the surface of ATP, and the agglomeration of nZVI particles was significantly weakened. The adsorption performance of nZVI@ATP for Pb2+ was greatly improved compared with that of ATP ore, in which the Fe/ATP mass ratio of 1:2 was the best loading ratio. Under the conditions of a temperature of 25 °C and a pH of 5.00, the initial concentration of Pb2+ was 700 mg/L, and the Pb2+ removal rate of nZVI@ATP was 84.47%. The adsorption of nZVI@ATP to Pb2+ was mainly a spontaneous endothermic reaction of heterogeneous surfaces, and the adsorption rate of nZVI@ATP to Pb2+ was proportional to pH in the range of 2–5.5. The presence of Na+, Mg2+, and Ca2+ can inhibit the removal of Pb2+, and Ca2+ has the strongest inhibition effect on the removal of Pb2+. The removal mechanism of Pb2+ by nZVI@ATP obtained from SEM-EDS, BET, XRD, FTIR and XPS included reduction, precipitation, and the formation of complexes.

Effect of Micro Nano-Structured Copper Additives with Different Morphology on Tribological Properties and Conductivity of Lithium Grease

ABSTRACT In order to explore the effect of micro nano-structured copper additives with different morphology on tribological properties and conductivity of lithium base grease, nano-sized copper sheets (denoted as Cu NSs), micro-sized copper wires (denoted as Cu MWs) and copper particles (denoted as Cu Ps) between micrometer and nanometer scale were prepared by liquid-phase chemical methods. The effects of synthetic variables such as reaction temperature, reaction time and pH value of reactant solution on the morphology of the final products were investigated. The as-prepared Cu NSs, Cu MWs, and Cu Ps were characterized by field emission scanning electron microscopy and X-ray diffraction. Their effects on the tribological properties and conductivity of lithium grease were investigated via ball-on-disk sliding tests and contact resistance measurements as well as morphology and element composition analyses of worn block surface. The experimental results show that the morphology of the product is significantly affected by the experimental conditions. This makes it feasible to fabricate copper additives with desired morphology by properly tuning the reaction conditions. Besides, the as-prepared copper additives can improve the tribological properties and conductivity of lithium base grease, because they can be adhered and deposited on rubbed steel surfaces to form boundary lubricating films consisting of cuprous oxide, cupric oxide, ferric oxide and other oxides.

Improved dyes separation performance of reduced graphene by incorporation MoS2 nanosheets

The hydrothermal reduced graphene (rGO) and the layered MoS2 nanosheets prepared by the liquid-phase stripping method were blended, and then the MoS2-rGO composite membranes were prepared on the polyvinylidene fluoride (PVDF) supporting membranes by vacuum filtration method. A variety of characterization methods such as Fourier transform infrared spectrometer (FT-IR), X-ray photoelectron spectroscopy (XPS) and X-ray diffractometer (XRD) were used to verify the successful introduction of MoS2 into rGO layers and the changes of interlayer structure of the MoS2-rGO membranes. Finally, the effect of MoS2 loading on separation performance of the MoS2-rGO composite membrane was investigated. The results show that the separation performance of the membrane with 33.33% of MoS2 loading (M−rG−3) is the most excellent. The permeability of M−rG−3 membrane is 118.21 L m-2h−1 bar−1, which is about 4.4 times that of the pristine rGO membrane. Meanwhile, the rejection of the M−rG−3 membrane for Methyl blue, Crystal violet, Rhodamine B, and Congo red all exceed 80%.

Enhancement in creep resistance of pristine polystyrene with incorporation of exfoliated 2D graphene nanosheets at low filler loading

Determination of the reliability and durability of polymers in structural applications is highly dependent on the resistance to time-dependent plastic deformation. In this study, creep behaviour and enhancement in creep resistance of polystyrene-graphene nanocomposites is investigated at low filler loading. Herein, 2D material (graphene) is synthesised by the liquid-phase exfoliation method ( LPE) using the tetrahydrofuran ( THF) solvent via batch sonication. Samples are characterised by Scanning Electron Microscopy ( SEM) for morphology analysis and X-rays Diffraction ( XRD) for identification of polystyrene-graphene (PS-G) peaks in nanocomposites. Additionally, Atomic Force Microscopy ( AFM) is employed to quantify sheet’s thickness and Optical Microscopy ( OM) to corroborate the dispersion of 2D sheets. The creep resistance of PS-G nanocomposites is measured at room temperature (25°C) by incorporating 2D sheets of flake length ∼359 μm with 0.1, 0.3, 0.5, 0.7 and 0.9 wt.%. A significant enhancement in the time to withstand constant creep load (1 N) is observed. The creep resistance of the samples exhibits a maximum increase of 79%, 258.24%, 647.25%, 417.58% and 760.44%, respectively, compared to pristine polystyrene. This increase in creep resistance resulted from intense interfacial contact between polymer chains and filler accompanied by adequate scattering/dispersion in the polymer matrix.

Efficient and stable core-shell α–Fe2O3/WS2/WOx photoanode for oxygen evolution reaction to enhance photoelectrochemical water splitting

In the present work, the WS2 nanosheets were prepared through a liquid-phase exfoliation method (LPE). Various techniques were then used to characterize thickness, length, and concentration of these nanosheets. WS2 nanosheets were also loaded on α–Fe2O3 photoanodes to prepare core-shell structured α–Fe2O3/WS2/WOx photoanodes. These core-shell structured α–Fe2O3/WS2/WOx nanorods have advantages of effective separation, decreased recombination of photo-generated electron-hole pairs, and increased electron transport properties, resulting in improved PEC performance. The best photoanode (α–Fe2O3/#4-WS2/WOx) had photocurrent densities of 0.98 and 2.1 mA cm−2 (with the lowest onset potential 0.54 VRHE and 0.47 VRHE) under front and back-side illumination, respectively, at 1.23 VRHE under 100 mW cm−2, which were about 13 and 30-fold higher than those of pure α-Fe2O3 photoelectrode. Furthermore, H2 and O2 production of α–Fe2O3/#4-WS2/WOx photoanode were 32 μmol.cm−2 and 15.3 μmol.cm−2, respectively at 1.23 VRHE under 100 mW cm−2 after 2 h.

Insight into the structural sensitivity of CuZnAl catalysts for CO hydrogenation to alcohols

The catalytic conversion of CO hydrogenation is a structure-sensitive reaction over Cu-based catalyst. It is very important to distinguish the structural differentiation and possible reaction pathway of Cu-based catalysts in methanol synthesis and ethanol/C2+OH synthesis. Herein, the activity of four types of CuZnAl catalysts is evaluated, and their structural differentiation is investigated. The CuZnAl catalyst (CZA) prepared by a complete liquid-phase (CLP) method after solid–liquid separation directly applied in the fixed bed reactor also shows the ability to synthesize ethanol and higher alcohols (C2+OH), with the selectivity of C2+OH in liquid product reaching up to 31.6% at the CO conversion of 10.6%. However, commercial methanol synthesis catalyst (CMC) displays the highest CO conversion (28.2%) and the poorest C2+OH selectivity (7.8%). After characterized by ICP, XRD, CO-TPD, N2O adsorption, XPS, SEM, TEM and in-situ DRIFTS techniques, it is discovered that the dispersion of Cu and the exposed Cu surface area significantly influences CO conversion. The selectivity of ethanol and C2+OH is related to the size and distribution of Cu, the architectural feature, and the chemical environment of Cu and Al. In-situ DRIFTS indicates that CHxO* species can be formed over different CuZnAl catalysts. However, the formed CHxO* species will be rapidly hydrogenated to produce methanol on CMC catalyst, while the step is inhibited on CZA catalyst. Additionally, a bridge-type adsorbed CO is only observed on CZA catalyst, which is beneficial for the formation of CHx intermediates, leading to the formation of ethanol and higher alcohols.

Preparation and properties of ZnMoO4 anode materials with polymer network gel method

Polymer network gel method combines the advantages of solid-phase method and liquid phase method, triggering acrylamide (AM) radical polymerization in aqueous solution and N, N′- methylene bis acrylamide (MBAM) active double bond cross-linking reaction, forming polymer chains to form a three-dimensional network. The polymer network space formed by the gel is bound and evenly distributed to the ions in the solution, thereby reducing the contact and aggregation of molecules and achieving the purpose of uniform particle size and small particle size. The principle diagram of network gel is shown in Figure. Using cubic zinc acetate and ammonium molybdate tetrahydrate as raw materials, cubic ZnMoO4 negative electrode materials were prepared with polymer network gel method. The polymer network gel method has various effects on the structure, morphology and electrochemical properties of materials. Besides, the calcination temperature and calcination time were also the key factors to the electrochemical properties of the materials. In this paper, the effects of the ratio of monomer and crosslinker, calcination temperature and calcination time on ZnMoO4 materials were studied by single variable method, the preparation process was optimized, and its characterization and electrochemical tests were carried out. After 100 cycles, the optimized ZnMoO4 electrode has a discharge capacity of 374.0 mAh· g−1, 332.5, 263.5 and 177.1 mAh · g−1 at current densities of 0.1, 0.5, 1.0 and 2.0 A g−1, respectively. The electrochemical results show that the optimized ZnMoO4 has high capacity, large rate capability and excellent cycle stability.

In-syringe cotton fiber-supported liquid extraction coupled with gas chromatography-tandem mass spectrometry for the determination of free 3-mono-chloropropane-1,2-diol in edible oils

In the current study, natural cotton fiber was served as the supporter of water, and the water acted as an extractant for liquid-phase microextraction of polar components in low-polar edible oils. An in-syringe extraction device was constructed to facilitate the extraction process by simply loading a certain amount of cotton fibers between the syringe needle and the plastic syringe tube. Then, the extraction process can be conveniently conducted by pull-push the syringe plunger. It can be regarded as a new type of dynamic liquid-phase microextraction method while operated more convent. For the feasibility study, the novel in-syringe cotton fiber-supported liquid extraction (CF-SLECF-SLE) pretreatment method was applied to extract free 3-mono-chloropropane-1,2-diol (3-MCPD) in edible oils. Specifically, the cotton fibers supported a certain amount of water by successfully pulling-pushing 1 mL of water and 1 mL of HEX in/out twice, respectively. Then, 2.0 mL of diluted oil sample (containing 0.4 g oil) was loaded in and out four times for extraction, during which process 3-MCPD was extracted into the supported water. The extracted 3-MCPD was desorbed with 1 mL of ethyl acetate (EA), derivatized with trimethyl silane imidazole (TMSI), and analyzed by gas chromatography-tandem mass spectrometry (GC-MS/MS). For three different spiked edible oils, the internal standard normalized matrix effect (IS-normalized ME) values were in ranges of 96.3–104.8% with RSD being 4.3%, benefiting the accurate quantitative analysis. The limit of quantification (LOQ) was calculated to be 2 ng/g, which met the regular determination requirement of 3-MCPD in edible oils. Satisfied linearity was obtained in 2–500 ng/g, with correlation coefficients (R2) being 0.998. The relative recoveries were in the ranges of 96.9–110.5%. The intra-/inter-day RSDs were less than 8.2% and 10.2%, respectively. The proposed method provides an efficient, simple, low-cost, and easy to automate strategy for determining free 3-MCPD in edible oils.

ПОЛУЧЕНИЕ МЕТАЛЛОМАТРИЧНЫХ СПЛАВОВ ДЛЯ ИЗНОСОСТОЙКИХ ЭЛЕКТРОИСКРОВЫХ ПОКРЫТИЙ

The study objective is to obtain and study metal matrix alloys based on NiAl intermetallic compound with different concentrations of Ni for forming wear-resistant coatings on steel 45. 
 The problems to which the paper is devoted are: obtaining electrode materials based on NiAl intermetallic compound with different concentrations of Ni and studying their structure; studying the mass transfer during electrospark deposition on steel 45; studying the comparative wear resistance of the coatings obtained. 
 Research methods: electrode alloys are obtained by the method of liquid-phase self-propagating high-temperature synthesis; electro spark alloying is used to create wear-resistant coatings; the microstructure of the obtained alloys is studied by the method of metallographic analysis.
 The novelty of the work: for the first time, the influence of different Ni concentration values on the wear resistance of NiAl electrospark coatings on steel 45 is studied.
 Study results: the microstructure of the obtained alloys consists of doped Cr and Co grains of NiAl matrix with a different Ni/Al ratio, along the boundaries of which the compounds of all alloy components are located. When forming coatings by electrospark method, time dependences of changes in anode erosion, cathode gain and mass transfer coefficient are obtained. 
 Conclusions: NiAl metal-based alloys with different concentrations of Ni were smelted using a liquid-phase SHS method using charge consisting of metal oxides and mineral concentrates containing tungsten and zirconium; the microstructure of the obtained alloys consists of doped Cr and Co grains baseds on NiAl, along which boundaries compounds of all the constituent components of the alloy are concentrated, including Zr and W. Experimental results of anode erosion, cathode gain, and mass transfer coefficient were obtained while forming the coatings with the alloys using electrospark method, and it was found during wear resistance tests that with an increase of Ni concentration in the alloy, the wear resistance increases.

Au doped In2O3 nanoparticles: Preparation, and their ethanol detection with high performance

Precious metals doping can greatly change the gas sensing performance of semiconductor metal oxide. Herein, the Au-doped In2O3 nanoparticles (NPs) were prepared via a combination solvothermal and liquid-phase reduction method, and the obtained nanoparticles were characterized by various techniques. The results indicated that Au nanocrystals with a diameter ca. 5 nm were uniformly distributed on the surface of the irregular In2O3 NPs. Importantly, compared with undoped In2O3, the specific surface area of all the Au-doped In2O3 NPs increased. And all the Au-doped In2O3 sensors greatly improved the gas sensing performance towards ethanol. The optimal operating temperature reduced from 240 °C for undoped In2O3 to 200 °C for Au-doped In2O3. Of them, the 4 wt% Au-doped In2O3 sensor displayed highly response (106 towards ethanol at 100 ppm) at the optimal operating temperature, good linear coefficient, high reproducibility, and long-term stability towards ethanol. Moreover, through the detection of seven gases including ethanol, such as methanol, acetone, benzene, formaldehyde, isopropanol, and nitrogen dioxide， we found that the fabricated sensor based on 4 wt% Au-doped In2O3 had good selectivity towards ethanol. Finally, the mechanism of the excellent performance of the 4 wt% Au-doped In2O3 sensor for ethanol was explained.

Enantiopure β3-Trifluoromethyl-β3-homoalanine Derivatives: Coupling with Boc-Protected Amino Acids and Conformational Studies of Peptides in Solid State

AbstractThe use of enantiopure β3-trifluoromethyl-β3-alkyl β-amino acids for the design of peptides would contribute to drastically enhance peptide stability in vivo. Moreover, the steric hindrance generated by the substituents on the tetrasubstituted carbon adjacent to the nitrogen function coupled to the electron-withdrawing effect of the trifluoromethyl group is more likely to influence the 3D conformation of the peptide. Herein, we describe a short, scalable and robust method to synthesize N- and/or C-protected enantiopure (R)- and (S)-β3-trifluoromethyl-β3-methyl β-amino acid derivatives and liquid-phase coupling methods suitable for incorporation of Boc-protected amino acids into short α/β- and β-peptides. Conformational studies of some of these original peptides via X-ray diffraction analysis highlighted intraresidue C6 hydrogen bonds within trifluoromethylated amino acids.

Synthesis and characterization of Sb2O3 nanoparticles by liquid phase method under acidic condition

Antimony trioxide (Sb2O3) nanoparticles were successfully synthesized via a facile and practical liquid phase method under acidic condition. The structure, composition and surface morphology of the as-prepared products have been characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), scanning electronic microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The as-obtained products revealed a cubic phase of Sb2O3 (JCPDS No. 05–0534) with a preferred plane of (222) and lattice spacing of a = 11.180 Å. Besides, Sb2O3 octahedra, spherical and polyhedral nanoparticles, coral-like nanorod and paddy-like nanosheets have also been synthesized by the modulating reaction time and solution pH value under acidic condition. According to the results of the time-dependent and pH-dependent experiments, the possible formation mechanisms for Sb2O3 nanocrystals with diverse morphologies have been proposed, which could be a favorable suggestion for the synthesis of other metal-oxide nanomaterials with morphology control.

EFFECT OF GRAIN-BOUNDARY SEGREGATION ON LOW-TEMPERATURE DEGRADATION OF ORAL 3Y-TZP CERAMICS CO-DOPED WITH GEO2AND TIO2

Purpose: To explore the improvement of its low temperature aging resistance by co-doping oral 3Y-TZP with TiO2and GeO2. Methods: After the samples of 3Y-TZP co-doped with GeO2and TiO2were prepared by mechanical ball milling, drying, and pressureless sintering, the microstructure was studied by scanning transmission electron microscope, energy spectrometer, and high angle annular dark field detector. After treatment in the autoclave, the conversion of all samples was measured by XRD. Results: After mechanical ball milling for 24 hours, the particle size of the composite powder of 3Y-TZP co-doped with GeO2and TiO2is uniform, distributed at about 50[Formula: see text]nm, the particle shape is basically spherical, the dispersion is good, but there is a small amount of agglomeration; Tetravalent stabilizers (Ge[Formula: see text], Ti[Formula: see text]) can inhibit the low-temperature aging effect of zirconia materials. With the increase of germanium oxide doping, the hydrothermal degradation resistance of zirconia can be improved. GeO2doped 3Y-TZP has better low temperature aging resistance than TiO2doped 3Y-TZP. With the increase of dopant content, the degree of grain boundary segregation increases, but even if the doping amount of Ge[Formula: see text] is small, the degree of grain boundary segregation can be comparable to that of Ti[Formula: see text] with a large doping amount. Conclusion: In this paper, the composite powder of 3Y-TZP co-doped with GeO2and TiO2with uniform particle size and good dispersion was prepared by mechanical ball milling. The preparation process is simple, the energy consumption is low, and the cumbersome processes of the co-precipitation method and liquid-phase method are avoided. On the other hand, adding GeO2and TiO2can enhance the low-temperature aging resistance of 3Y-TZP ceramics. GeO2is superior to TiO2in low-temperature degradation resistance, which can be used as the first choice. This study contributes to the research on doping cations of dental zirconia and provides a reference for dentists to choose a reasonable zirconia material.

Morphological, Structural and Thermal Properties of Silane-treated Date Palm Fibers

ABSTRACT This investigation aims to estimate the contribution of fluoro and non-fluorosilane to the surface properties of raw date palm fibers (DPFs). The raw DPFs were successfully functionalize using fluoro [trichloro(1h,1h,2h,2h-perfluorooctyl)] and non-fluorosilane [octadecyltrichloro] coupling agents using liquid-phase silanization method. The structure, chemical composition and thermal properties of functionalization have been proved by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction and Fourier transform infrared spectroscopy (FTIR). TGA and XRD results indicate the reduction of the amorphous cellulose as an end result in silane modified DPF a have higher fraction of crystalline cellulose. The thermal properties of DPFs from the TGA results showed an increase dramatically after the treatment with silane coupling agents. The degradation temperature of the DPFs reached above 400°C with fluoro and non-fluorosilane, which is reasonably promising for using these fibers in hydrophobic polymer composites as reinforcing material.

Surface modification and stability performance of black phosphorus nanosheets based on metal ions/graphene

As a novel two-dimensional nanomaterial, black phosphorus nanosheets (BPNs) have good biocompatibility, biodegradability, and broadband saturable light absorption properties and, thus, have become a hot research topic in the biomedical field. However, BPNs suffer from poor stability caused by easy oxidative degradation and deactivation, and how to surface functionalize BPNs to improve their stability is a key issue to be solved. In this paper, we propose to realize the preparation of BPNs by the liquid-phase exfoliation method and study the surface functionalization modification of BPNs by silver ions (Ag+) and graphene oxide (GO). First, the preparation and characterization of BPNs were carried out by the liquid-phase exfoliation method to investigate the effect of process condition regulation on the planar size and thickness of BPNs, and the functionalization modification of BPNs by Ag+ and GO was carried out around the goal of enhancing the stability of BPNs. The experimental results showed that the stability of BPNs@Ag+ and BPNs@GO was significantly enhanced compared with that of unmodified BPNs. This study can be a reference for the future development of BP in the medical field.

Towards the Synthesis of a Heterocyclic Analogue of Natural Cyclooligopeptide with Improved Bio-properties.

The present investigation is targeted towards the synthesis of a novel analogue of a natural peptide of marine origin. Marine sponges are enriched with bioactive secondary metabolites, especially circu-lar peptides. Heterocycles are established organic compounds with potential biological value. Tak-ing into consideration the bio-properties of heterocycles and marine sponge-derived natural pep-tides, an effort was made for the synthesis of a heterocyclic analogue of a natural cyclopeptide. A heterocyclic analogue of a sponge-derived proline-containing cyclic peptide, rolloam-ide A, was synthesized by interaction of Boc-protected L-histidinyl-L-prolyl-L-valine and L-prolyl-L-leucyl-L-prolyl-L-isoleucine methyl ester and compared with synthetic rolloamide A with bioac-tivity against bacteria, fungi, and earthworms. The synthesis of cycloheptapeptide was accomplished employing the liquid phase method. The larger peptide segment was prepared by interaction of Boc-protected L-prolyl-L-leu-cine with L-prolyl-L-isoleucine methyl ester. Similarly, the tripeptide unit was synthesized from Boc-protected L-histidinyl-L-proline with L-valine ester. The linear heptapeptide segment (7) was cyclized by utilizing pentafluorophenyl (pfp) ester, and the structure was elucidated by elemental and spectral (IR, 1H/13C NMR, MS) analysis. The peptide was also screened for diverse bioactivities such as antibacterial, antifungal, and potential against earthworms and cytotoxicity. The novel cyclooligopeptide was synthesized with 84% yield by making use of car-bodiimides. The synthesized cyclopeptide exhibited significant cytotoxicity against two cell lines. In addition, promising antifungal and antihelmintic properties were observed for newly synthesized heterocyclic peptide derivative (8) against dermatophytes and three earthworm species at 6 μg/mL and 2 mg/mL, respectively. Solution-phase technique employing carbodiimide chemistry was established to be promising for synthesizing the cycloheptapeptide derivative (8), and C5H5N was proved to be a better base for heptapeptide circling when compared to N-methylmorpholine and triethylamine.

Pd/BP2000 Nanocomposites: Efficient Catalyst for Hydrolytic Dehydrogenation of Ammonia-borane

In current work, the activity of BP2000 supported Pd nanoparticles (NPs) were researched based on hydrolysis of ammonia borane (AB) reaction. Borane-tert-butylamine used for reduction of palladium (II) acetylacetonate for synthesize procedure of Pd NPs under mild conditions. As prepared Pd NPs were assembled on the BP2000, by liquid-phase self-assembly method. X-ray diffraction (XRD), transmission electron microscopy (TEM) and inductively coupled plasma-mass spectroscopy (ICP-MS) -advanced analytical techniques- were performed for detailed characterization. BP2000-supported Pd NPs were exhibited excellent activity and stability for the hydrolysis of AB. Pd/BP2000 nanocatalyst were showed the enhance catalytic activity that calculated turnover frequency (TOF) of 20.4 min−1. The detailed report clarified the kinetics of Pd/BP2000 nanocatalyst parameters on catalyst amount, AB concentration, temperature and reusability. After the hydrolysis of AB with Pd/BP2000 nanocatalyst, activation energy of reaction was calculated to be 41.5 kJ mol−1.