Effects of Fiber Diameter on Crack Resistance of Asphalt Mixtures Reinforced by Basalt Fibers Based on Digital Image Correlation Technology.

It is now more popular to use basalt fibers in the engineering programs to reinforce the crack resistance of asphalt mixtures. However, research concerning the impact of the basalt fiber diameter on the macro performance of AC-13 mixtures is very limited. Therefore, in this paper, basalt fibers with three diameters, including 7, 13 and 25 µm, were selected to research the influences of fiber diameter on the crack resistance of asphalt mixtures. Different types of crack tests, such as the low temperature trabecular bending test (LTTB), the indirect tensile asphalt cracking test (IDEAL-CT), and the semi-circular bend test (SCB), were conducted to reveal the crack resistance of AC-13 mixtures. The entire cracking process was recorded through the digital image correlation (DIC) technique, and the displacement cloud pictures, strain, average crack propagation rate (V) and fracture toughness (FT) indicators were used to evaluate the crack inhibition action of the fiber diameter on the mixture. The results showed that the incorporation of basalt fiber substantially improved the crack resistance, slowed down the increase of the displacement, and delayed the fracture time. Basalt fiber with a diameter of 7 µm presented the best enhancement capability on the crack resistance of the AC-13 mixture. The flexibility index (FI) of the SCB test showed a good correlation with V and FT values of DIC test results, respectively. These findings provide theoretical advice for the popularization and engineering application of basalt fibers in asphalt pavement.

Saponins from Panax bipinnatifidus Seem.: New strategy of extraction, isolation, and evaluation of tyrosinase inhibitory activity based on mathematical calculations.

A hyphenated accelerated solvent extraction (ASE) technique coupled with centrifugal partition chromatography (CPC), ultra high performance liquid chromatography (UPLC), and mass spectrometry (MS) was established. The CPC fractions were prepared using the hyphenated technique. Subsequently, tyrosinase inhibitory activities of the CPC fractions were experimentally evaluated, and the activities of individual components were calculated theoretically. This new approach was applied to saponin fractions obtained from 10.0g of raw Panax bipinnatifidus Seem. via a biphasic solvent system of ethyl acetate/n-butanol/methanol/water (2:3:2:5, v/v/v/v). The CPC fractions monitoring was performed using an online UPLC/PDA system at 5-min intervals. The tyrosinase inhibitory activities of all fractions were analysed using the fluorescence method. Mathematical calculations indicated that the inhibition rates of the ginsenosides Rh1, Rh2, Rg1, Rg2, and chikusetsusaponin L5 were all above 50.00%, showing potential for further development. The results were confirmed by comparison with authentic standards.

Efficient combination of circulating ultrasound-assisted extraction and centrifugal partition chromatography for extraction and on-line separation of chemical constituents from Stellera chamaejasme L.

INTRODUCTION: Sample preparation is a crucial step in medicinal herb analysis because the desired chemical components need to be extracted from the herbal materials for further separation and characterisation. Thus, the development of " modern" sample preparation techniques with significant advantages over conventional methods is very important. OBJECTIVE: The aim of this study was the development of a new preparation method using circulating ultrasonic-assisted extraction (CUAE) coupled with centrifugal partition chromatography (CPC) for continuous extraction and on-line isolation of chemical constituents from Stellera chamaejasme L. METHODOLOGY: The stationary or mobile phase was used as the extraction solvent. Extraction parameters, including the ultrasound power, extraction time, temperature, and liquid:solid ratio, were optimised using a response surface methodology. RESULTS: The extraction time, temperature, and power considerably affected the extraction yield. The optimised extraction parameters were an ultrasound power of 800 W, extraction time of 30 min, extraction temperature of 70 °C, and liquid:solid ratio of 8 mL/g. The solvent system for CUAE and CPC was optimised using mathematical equations, and the two-phase solvent system of n-hexane:ethyl acetate:methanol:water at a volume ratio of 3:5:4:6 was calculated. Four target compounds (daphnoretin, chamaechromone, neochamaejasmin A, and isochamaejasmin) with purities above 96% were successfully extracted and isolated on-line via CUAE/CPC. CONCLUSION: Compared with the reference extraction methods, the instrumental setup achieved a scientific and systematic extraction and isolation of natural products and has great potential for industrial application.

Ultrasound-assisted dynamic extraction coupled with parallel countercurrent chromatography for simultaneous extraction, purification, and isolation of phytochemicals: application to isoflavones from red clover.

A novel procedure comprising ultrasonic-assisted dynamic extraction (UADE) coupled with two countercurrent-chromatography systems (parallel countercurrent chromatography, PCCC) was developed. This technique offers the possibility for simultaneous extraction, solvent configuration, purification, and isolation of target compounds. This new approach was applied to the fractionation and purification of isoflavones from red clover. The two-phase solvent system was prepared by automating the equipment. The lower aqueous phase of the two-phase solvent system was used as the UADE solution and as the mobile phase for PCCC. After the extraction and purification steps, the purified sample was pumped into the countercurrent chromatography 1 (CCC1) column for the first isolation step. During CCC1 separation, the sample was enriched and purified and then pumped into the CCC2 column for the second isolation step. After completion of the first cycle of UADE-PCCC steps, the second-cycle experiments were performed. Using this sequence, five target compounds, daidzein, prunetin, genistein, irilone, and maackiain, with >95.31 % purity were successfully extracted and isolated using the two-phase solvent system of n-hexane-ethyl acetate-ethanol-water (0.623:1.00:0.99:1.246, v/v). With this instrumental setup, scientific and systematic extraction and isolation of natural products was achieved, and this technique has great potential for industrial application. Graphical Abstract Simplified schematic of instrumental setup of UADE combined with two HSCCC instruments.

Circulating ultrasound-assisted extraction, countercurrent chromatography, and liquid chromatography for the simultaneous extraction, isolation, and analysis of the constituents of Uncaria tomentosa.

A hyphenated automated technique for the online extraction, isolation, analysis, and identification of natural organic compounds was established. Circulating ultrasound-assisted extraction (CUAE) was coupled with countercurrent chromatography (CCC), high performance liquid chromatography (HPLC), and a diode array detector (DAD). This approach was applied to the fractionation and purification of alkaloids from Uncaria tomentosa. A biphasic solvent system of chloroform-methanol-water (6:4:5, v:v:v) was used for the CUAE and CCC separation of compounds from 500 g of U. tomentosa. Two CUAE/CCC/HPLC/DAD modes were established. Either the upper aqueous phase or the lower organic phase of the solvent system could be used as the extraction solvent. The target compounds were extracted by CUAE, and the extract was pumped into a sample loop before being directly injected into the CCC column, or pre-purified using a flash chromatography column before injection. The target compounds were eluted using either the organic or aqueous phase of the solvent system and the fractions were monitored using a UV detector. The target fractions were collected by a sample loop via a six-port valve, and analyzed by HPLC/DAD for purity and structural identification. This system isolated of 8.2mg, 7.4 mg, and 12.9 mg of rhynchophylline, corynoxine, and corynoxine B with HPLC purities of 96.15%, 95.34%, and 95.49%, respectively via the first mode; and isolated 26.6 mg, 24.6 mg, and 45.3mg of rhynchophylline, corynoxine, and corynoxine B with a HPLC purities of 98.22%, 97.18%, and 97.93% via the second mode.

Development of "ultrasound-assisted dynamic extraction" and its combination with CCC and CPC for simultaneous extraction and isolation of phytochemicals.

A new method for the extraction of medicinal herbs termed ultrasonic-assisted dynamic extraction (UADE) was designed and evaluated. This technique was coupled with counter-current chromatography (CCC) and centrifugal partition chromatography (CPC) and then applied to the continuous extraction and online isolation of chemical constituents from Paeonia lactiflora Pall (white peony) roots. The mechanical parameters, including the pitch and diameter of the shaft, were optimized by means of mathematical modeling. Furthermore, the configuration and mechanism of online UADE coupled with CCC and CPC were elaborated. The stationary phases of the two-phase solvent systems from CCC and CPC were utilized as the UADE solution. The extraction solution was pumped into the sample loop and then introduced into the CCC column; the target compounds were eluted with the lower aqueous phase of the two-phase solvent system. During the CCC separation, the extraction solution was continuously fed in the sample loop by turning the ten-port valve; the extraction solution was then pumped into the CPC column and eluted by the mobile phase of the two-phase solvent system mentioned above. When the first cycle of the UADE/CCC/CPC was completed, the second cycle experiment could be carried out, and so on. Four target compounds (albiflorin, benzoylpaeoniflorin, paeoniflorin, and galloylpaeoniflorin) with purities above 94.96% were successfully extracted and isolated online using the two-phase solvent system comprising ethyl acetate-n-butanol-ethanol-water (1:3.5:2:4.5, v/v/v/v). Compared with conventional extraction methods, the instrumental setup of the present method offers the advantages of automation and systematic extraction and isolation of natural products.

Crystal structure of poly[{µ-N,N'-bis[(pyridin-4-yl)meth-yl]oxalamide}-µ-oxalato-cobalt(II)].

In the polymeric title compound, [Co(C2O4)(C14H14N4O2)] n , the Co(II) atom is six-coordinated by two N atoms from symmetry-related bis-[(pyridin-4-yl)meth-yl]oxalamide (BPMO) ligands and four O atoms from two centrosymmetric oxalate anions in a distorted octa-hedral coordination geometry. The Co(II) atoms are linked by the oxalate anions into a chain running parallel to [100]. The chains are linked by the BPMO ligands into a three-dimensional architecture. In addition, N-H⋯O hydrogen bonds stabilize the crystal packing.

Crystal structure of poly[aqua-[µ-1,1'-(9,9-dimethyl-9H-fluoren-2,7-di-yl)di-1H-imidazole](µ-naphthalene-1,4-di-carboxyl-ato)nickel(II)].

In the title compound, [Ni(C12H6O4)(C21H18N4)(H2O)] n , the Ni(II) cation is coordinated by three carboxyl-ate O atoms of two naphthalene-1,4-di-carboxyl-ate anions, one water mol-ecule and two N atoms of two 1,1'-(9,9-dimethyl-9H-fluoren-2,7-di-yl)di-1H-imidazole (DFDI) ligands, giving rise to a slightly distorted octa-hedral geometry. The Ni(II) ions are linked by the DFDI ligands into chains, which are further connected by the carboxyl-ate anions into double chains that elongate in the the b-axis direction. These double chains are linked by centrosymmetric pairs of O-H⋯O hydrogen bonds into layers parallel to (10-1). The asymmetric unit consists of one crystallographically independent Ni(II) cation, one carboxyl-ate and one DFDI ligand, as well as of one water mol-ecule, all of them located in general positions.

Pressurized liquid extraction coupled with countercurrent chromatography for systematic isolation of chemical constituents by preprogrammed automatic control.

Pressurized liquid extraction (PLE) coupled with high-speed countercurrent chromatography (HSCCC) via an automated procedure was firstly developed to extract and isolate ginsenosides from Panax quinquefolium. The experiments were designed under the guidance of mathematical model. The partition coefficient (K) values of the target compounds and resolutions of peak profiles were employed as the research indicators, and exponential function and binomial formulas were used to optimizing the solvent systems and flow rates of the mobile phases in a three-stage separation. In the first stage, ethyl acetate, n-butanol, and water were simultaneously pumped into the solvent separator at the flow rates 11.0, 10.0, and 23.0mL/min, respectively. The upper phase of the solvent system in the solvent separator was used as both the PLE solvent and the HSCCC stationary phase, followed by elution with the lower phase of the corresponding solvent system to separate the common ginsenosides. In the second and third stages, rare ginsenosides were first separated by elution with ethyl acetate, n-butanol, methanol, and water (flow rates: 20.0, 3.0, 5.0, and 11.0mL/min, respectively), then with n-heptane, n-butanol, methanol, and water (flow rates: 17.5, 6.0, 5.0, and 22.5mL/min, respectively). Nine target compounds, with purities exceeding 95.0%, and three non-target compounds, with purities above 84.48%, were successfully separated at the semipreparative scale in 450min. The separation results prove that the PLE/HSCCC parameters calculated via mathematical model and formulas were accurately and scientifically. This research has opened up great prospects for industrial automation application.

Application of accelerated solvent extraction coupled with high-performance counter-current chromatography to extraction and online isolation of chemical constituents from Hypericum perforatum L.

Accelerated solvent extraction (ASE) coupled with high-performance counter-current chromatography (HPCCC) was successfully used for the extraction and online isolation of five chemical constituents from the plant Hypericum perforatum L. The upper phase of the solvent system of ethyl acetate-methanol-water (5:2:5, v:v:v) was used as both the ASE solvent and the HPCCC stationary phase. Two hydrophobic compounds including 28.4 mg of hyperforin with a HPLC purity of 97.28% and 32.7 mg of adhyperforin with a HPLC purity of 97.81% were isolated. The lower phase of ethyl acetate-methanol-n-butanol-water (5:2:2.5:12, v:v:v:v) was used as both the ASE solvent and CCC stationary phase. Three hydrophilic compounds of 12.7 mg of 3,4,5-O-tricaffeoylquinic acid with a HPLC purity of 98.82%, 15.2 mg of 1,3,5-O-tricaffeoylquinic acid with a HPLC purity of 99.46% and 42.5mg of 3-O-caffeoylquinic acid with a HPLC purity of 96.90%, were obtained in a one-step extraction-separation process with less than 3h from 10.02 g of raw material of H. perforatum. The targeted compounds isolated, collected and purified by HPCCC were analyzed by high performance liquid chromatography (HPLC), the chemical structures of all five compounds above mentioned were identified by UV, MS and NMR.

Solvent gradient elution for comprehensive separation of constituents with wide range of polarity in Apocynum venetum leaves by high-speed counter-current chromatography.

A novel gradient elution was efficiently utilized for the separation of the chemical components with a wide range of polarity from the mixed extract of the Chinese medicinal herb Apocynum venetum or mixed standards by high-speed counter-current chromatography. Three sets of solvent systems, n-hexane-ethyl acetate-methanol-water (1.5:3.5:2:4.5 v/v/v/v), ethyl acetate-methanol-water (5:2:5 v/v/v) and n-butanol-methanol-water (5:1:5 v/v/v) were used for the one-step elution. The separation was initiated by filling the column with the lower phase of n-hexane-ethyl acetate-methanol-water (1.5:3.5:2:4.5 v/v/v/v) as a stationary phase followed by elution with the upper phase of n-hexane-ethyl acetate-methanol-water (1.5:3.5:2:4.5 v/v/v/v) to separate the hydrophobic compounds (tail to head). Then the mobile phase was switched to the upper phase of ethyl acetate-methanol-water (5:2:5 v/v/v) to elute the moderate hydrophobic compounds, and finally the hydrophilic compounds still retained in the column were fractionated by eluting the column with the upper phase of n-butanol-methanol-water (5:1:5 v/v/v). A total of 13 compounds including adhyperforin, hyperforin, amentoflavone, biapigenin, quercetin, astragalin, trifolin, isoquercetin, hyperside, acetyled hyperside, rutin, chlorogenic acid and quercetin-3-O-ß-D-glucosyl-ß-D-glucopyranoside were successfully separated via the three sets of solvent systems in one-step operation for 90 min.

Electrochemical preparation and structural characterization of platinum thin film on a polypyrrole film modified ITO electrode.

Platinum nanostructures have been fabricated by electrochemical deposition of platinum onto indium tin oxide (ITO) glass substrate modified with thin polypyrrole film. The crystal size and the number density of the platinum nanoparticles have been examined by varying several deposition parameters, including the thickness of the PPy film and the current densities for platinum deposition. Optimal conditions for uniform growth of nanoparticles well-dispersed on the ITO have been determined, along with insight into the mechanism of crystal growth. The PPy film thickness principally affect the size and number density of the nanoparticles, while the platinum deposition current densities could be used to regulate the shape of the nanoparticles. In addition, the flower-like platinum nanoparticles showed high catalytic activity on electrochemical oxidation of methanol, and its activity was measured to be approximately 1.9 times that of bare platinum.

Controlled synthesis of LaPO(4) and CePO(4) nanorods/nanowires.

LaPO(4) and CePO(4) nanorods/nanowires with controlled aspect ratios have been successfully synthesized using a hydrothermal microemulsion method under mild conditions. It has been shown that the obtained LaPO(4) has a monoclinic structure, while CePO(4) exists in the hexagonal structure. Uniform nanorods/nanowires with diameters of 20-60 nm and lengths ranging from several hundreds of nanometres to several micrometres were obtained. The aspect ratios of the obtained 1D nanostructures can be fine-tuned by simply changing the [H(2)O ]/[surfactant] molar ratios. The possible growth mechanism of LaPO(4) and CePO(4) nanorods/nanowires was explored in detail.

A simple route towards CuO nanowires and nanorods.

CuO nanowires and nanorods were synthesized through a novel controllable solution-phase hydrothermal method using a nonionic surfactant polyethylene glycol (PEG) as the structure-directing template. The lengths of obtained 1D CuO nanostructures could be successfully controlled through choosing different molecular weights of PEG. The phase structures and morphologies were investigated by XRD, TEM, HRTEM and SAED. The formation mechanisms of the nanorods and nanowires were investigated and discussed on the basis of the experimental results.

Shape and size control of ZnO nanostructures via a simple solution route.

ZnO nanostructures with different morphologies were synthesized by condensing the Zn(OH)4(2-) precursors under hydrothermal conditions in the presence of a surfactant, cetyltrimethylammonium bromide (CTAB). Shape and size control of ZnO nanostructures was achieved by relatively simple variations of molar ratio of CTAB to Zn(OH)4(2-). With a higher molar ratio, ZnO nanotubes were obtained, whereas with a lower molar ratio, ZnO nanorods were formed; furthermore, with a moderate w value, the coexistence of ZnO nanorods and nanotubes was also observed. The photoluminescence of ZnO nanorods and nanotubes was also investigated.

A new type of single-helix coordination polymer with mixed ligands [M2(phen)2(e,a-cis-1,4-chdc)2(H2O)2]n (M=Co and Ni; phen=1,10-phenanthroline; chdc=cyclohexanedicarboxylate).

A new family of single-stranded helices coordination polymers with mixed ligands, [M2(phen)2(e,a-cis-1,4-chdc)2(H2O)2]n (1, M=Co; 2, M=Ni; chdc=cyclohexanedicarboxylic acid; phen=1,10-phenanthroline), were prepared under hydrothermal conditions and characterized by elemental analyses, IR spectra, TG analysis, and single-crystal X-ray diffraction analysis. X-ray crystal structural analyses reveal that 1 and 2 are isomorphic and belong to the monoclinic system. C40H36Co2N4O10, P2(1)/c, a=10.0566(5) A, b=8.8843(5) A, c=20.2912(14) A, beta=100.052(3) degrees, Z=2 for 1; and C40H36Ni2N4O10, P2(1)/c, a=9.8921(6) A, b=9.0151(4) A, c=20.1628(17) A, beta=100.31(2) degrees, Z=2 for 2. In the structures of 1 and 2, the 1,4-chdc ligand possesses only one kind of e,a-cis-conformation although there are both cis- and trans-conformations in the raw material. Two oxygen atoms of one carboxyl in 1,4-chdc ligand and another oxygen atom of contraposition carboxyl link adjacent Co or Ni atoms into an infinite 1-D zigzag chain. The most attractive structural feature of 1 and 2 is that they both exhibit an infinite chiral chainlike structure with 2(1) helices along the b axis. In addition, the right-handed and the left-handed chains are alternate. Meanwhile, the adjacent chains of 1 and 2 are linked via hydrogen bonds into 2-D network structures, which further form 3-D frameworks via pi-pi interactions of 1,10-phen.

Selected-control synthesis of PbO2 and Pb3O4 single-crystalline nanorods.

Reaction of Pb(OH)3- with ClO- in the presence of surfactant CTAB under conventional conditions resulted in PbO2 nanorods, whereas the reaction under hydrothermal conditions afforded Pb3O4 nanorods, as confirmed by X-ray powder diffraction and transmission electron microscopy (TEM). Selected area electron diffraction (SEAD) and high-resolution TEM (HRTEM) revealed that both PbO2 and Pb3O4 nanorods are single crystalline. For the formation of Pb3O4 nanorods, it is reasonable that PbO2 slowly decomposes to Pb3O4 under hydrothermal conditions, while retaining the morphology of PbO2.

[Catalytic spectrophotometry for the determination of trace cobalt by the new indicating reaction].

A kinetic spectrophotometric method for the determination of trace cobalt(II) was established. It was based on the Co(II) catalyzing the discoloring reaction of malachite green by potassium periodate in the presence of HBO3-Na2B4O7 solution (pH = 8.5). The sensitivity of the method is 2.1 x 10(-10) g.mL-1. The range of determination is 0-0.8 microgram.25 mL-1. The apparent activation of catalytic reaction is 37.94 kJ.mol-1. The method has been applied to the determination of cobalt in tea leaf and injection of vitamin B12 samples with satisfactory results.