Smaller Particle Size Distribution Research Articles

Magnesium-coated hydroxyapatite/titania cement as a potential nanomotor-based coating on orthopedic implant

A hybrid strategy was proposed to fabricate a nanostructured cement coating on Ti6Al4V as a potential nanomotor-based surface modification of orthopedic implant for targeted delivery of therapeutics in the treatment of infectious nonunion. For this purpose, hydroxyapatite/titania (HA/TiO2) composite coating was generated on Ti6Al4V by electrophoretic deposition (EPD), followed by the physical vapor deposition (PVD) of Mg coating on HA/TiO2. The microstructural investigation showed a distinct bimodal particle size distribution of small spherical-shaped particles (90 ± 30 nm) and large particles (700 ± 250 nm). Rietveld refinement yielded a crystallite size of 42.4 nm for the complex structure. The proposed coating can be embodied as a nanomotor, which provides kinetic movement via the formation of bubbles in an aqueous biological medium for the improvement of propelling efficiency in a drug-loaded implant.

Ultrafast Nanocrystallization of BaF2 in Oxyfluoride Glasses with Crystal-like Nanostructures: Implications for Upconversion Fiber Devices

Transparent glass–ceramic fibers containing fluoride nanocrystals are attracting attention as upconversion devices. In this paper, a material design is proposed that eliminates the need for heat treatment processes. The impact of short- to medium-range structures on the crystallization of glasses was investigated to enable nanocrystallization in the quenching process via ultrafast nucleation. In this study, the short- to medium-range structures of (33.3 – x/3)BaF2–xZnO–(66.7 – 2x/3)B2O3 glasses were investigated by 11B- and 19F-magic-angle spinning nuclear magnetic resonance spectroscopy, molecular dynamics simulations, and the high-energy synchrotron X-ray diffraction. After heat treatment, glasses with x > 40 formed BaF2 nanocrystals with a diameter of ∼5 nm and a small particle size distribution (<1 nm). Based on the high-energy synchrotron X-ray diffraction, the critical size of the nuclei was estimated to be 4 nm, which was similar to the size of the precipitated crystals. Obvious selectivity in the binding was observed: F– preferred Ba2+ and O2– preferred B3+, whereas Zn2+ was bound to both anions. The binding selectivity caused a bicontinuous structure of oxide and fluoride domains, and the fluoride-related structure factors and bond distance were very similar to the peak positions of the precipitated crystals. Er3+-doped glasses with x > 40 showed upconversion luminescence with a spectrum similar to that of BaF2. These results suggested the pre-existence of a crystal-like structure with a composition, density, and ordering similar to those of the precipitated crystals. Moreover, glass with the modified composition was successfully crystallized during press-quenching of the melt and the fiber drawing process. These results could facilitate the production of photonic components such as nanocrystallized glass fibers and microspheres for upconversion lasers as well as a wide variety of glass–ceramic products.

Psilocybin: Characterization of the Metastable Zone Width (MSZW), Control of Anhydrous Polymorphs, and Particle Size Distribution (PSD).

Psilocybin, a serotonergic agonist, was granted a “breakthrough therapy” status by the Food and Drug Administration for clinical trials involving major depressive disorder and treatment-resistant depression. The direct phosphorylation of psilocin to psilocybin that uses a fast crystallization associated with a kinetically controlled process resulted in a smaller particle size distribution. Herein, the measurement of the metastable zone width (MSZW) and nucleation induction enabled a thermodynamically controlled crystallization process, which leads to the formation of a crystal structure with stronger interactions, controlled particle size distribution (PSD), and improved impurity profile. Employing a high-resolution inline microscopy viewer allowed the real-time monitoring of the crystallization process and the measurement of the particle size. We also present a comprehensive study of the formation of polymorph B (trihydrate), polymorph A (anhydrate), and polymorph H (anhydrate) using water recrystallization, which indicates that the formation of polymorph B (trihydrate) is independent of the crystallization method. However, polymorphs A and H are dependent on the mode of drying: drying at room temperature under vacuum gives rise to mainly polymorph A, and when heated even at relatively low temperatures, a mixture of polymorphs A and H beings to form.

Characterisation of Spheroidised tungsten carbide metco 32c powder using radio frequency plasma

Metco 32C is a coarse grey powder, which mostly consists of tungsten carbide and cobalt; with small traces of nickel, chromium, boron, iron silicon and carbon. Metco 32C powder has the role of supporting oxidation and corrosion resistance at high temperatures as well as increasing the hardness of the coated materials. The spheroidal morphology of Metco 32C improves flowability during layer application methods such thermal spraying. There has been a growing interest in the development / improvement of methods producing powders of cast tungsten carbide and other high-melting-point materials of uniform composition, characterised by a high sphericity of the particles and having higher physical-mechanical properties. Spherical particles are generally preferred in the additive manufacturing process as they pack together for uniform powder bed density, better flowability in machinery, eliminate internal cavities and fractures resulting in a better quality of final product. Similarly, thermal spraying processes also require dense, spherical particles to ensure consistency and reproducibility of the feeding mechanism as well as interaction between the feedstock and thermal spraying heat source. The process of transforming irregularly shaped powder particles into spherical shapes is known as the spheroidisation process and this can be achieved by plasma spheroidisation. It was found that the spheroidisation ratio of the powder increased as the plasma plate power increased. A decrease in density was observed as plasma power increased. The spheroidised powders have a smaller particle size distribution (PSD) than the feed powders (un-spheroidised). The XRD results showed that as the plasma plate power increased the WC phase composition decreased, subsequently the phase composition of W2C increased.

Effects of physical and chemical properties of ceramic hand moulds on natural rubber latex glove film formation

Plaster and stoneware hand moulds were fabricated and used in the NR latex glove preparation. The raw materials characteristics combined to influence the hand mould surface properties through the adhesion-cohesion force, interfacial tension, contact angle, packing density. The stoneware hand mould fired at 800°C, fabricated from a smaller particle size distribution, with high zeta potential and interfacial interaction, and high specific surface area was shown to be superior to the plaster hand mould typically used in making NR latex products. The obtained NR latex films were characterised for various physical properties, namely appearances, thickness, tackiness, porosity, smoothness, optical clarity, and effusion.

Characterization of Moringa oleifera leaf and seed protein extract functionality in emulsion model system

This study provides a comparative overview of Moringa oleifera leaf and seed protein extract (LPE and SPE, respectively) functionality in emulsions. Raw seed cake (RS) had more protein (45.8%) than raw leaf (RL) (27.4%). RL comprised higher polyphenol and flavonoid content than RS, Granny Smith apples, and Goji berries. Protein functionality data revealed that LPE had excellent solubility, and emulsifying properties than SPE at pH 7.0. In contrast, SPE had relatively strong surface hydrophobicity. At pH 7.0, leaf extract emulsions (LEE) possessed relatively small particle size distribution, strong negative charge, excellent stability, and minimum sedimentation velocity. On contrary, at pH 3.5, particle size, and velocity increased, contributing to monodisperse sedimentation. Seed extract emulsions (SEE) had an overall large particle size and demonstrated fast and extensive creaming and sedimentation at both pH conditions. Our findings indicate that M. oleifera leaf protein extracts have considerable potential for use in emulsion-based foods.

Effects of fumed silica flow aids on flowability and packing of metal powders used in Binder-Jetting additive manufacturing process

Binder-Jetting is a fairly new sinter-based additive manufacturing technology for metals. Due to sintering, small particle size distributions are favorable, yet they are limiting the printing process due to bad flowability and compaction. This paper aims to resolve this contradiction by adding flow aids to powders used in Binder-Jetting. Therefore 5 different powders with successively decreasing particle size distributions ranging from 32 µm (D90) to 5 µm (D90) are combined with 2 different fumed silica (aerosil) flow aids. Improvements are measured by the use of apparent and tap density as well as hausner ratio. Results show that the mixing process for flow aids and powders has significant influence on the improvements. Moreover, the amount of aerosil is a key criterion for optimized flow behavior. Improvements up to 42 % for apparent and 11 % for tap density are achieved. Hausner ratio can be improved up to 34 %. Preliminary printing results indicate that increased flowability and packing behavior also increases powder bed density and green density. The results are in line with existing theories regarding the use of flow aids in powders used in other industries and can be now be adopted for metal powders as well.

Design and Characterization of Maltoheptaose-b-Polystyrene Nanoparticles, as a Potential New Nanocarrier for Oral Delivery of Tamoxifen.

Tamoxifen citrate (TMC), a non-steroidal antiestrogen drug used for the treatment of breast cancer, was loaded in a block copolymer of maltoheptaose-b-polystyrene (MH-b-PS) nanoparticles, a potential drug delivery system to optimize oral chemotherapy. The nanoparticles were obtained from self-assembly of MH-b-PS using the standard and reverse nanoprecipitation methods. The MH-b-PS@TMC nanoparticles were characterized by their physicochemical properties, morphology, drug loading and encapsulation efficiency, and release kinetic profile in simulated intestinal fluid (pH 7.4). Finally, their cytotoxicity towards the human breast carcinoma MCF-7 cell line was assessed. The standard nanoprecipitation method proved to be more efficient than reverse nanoprecipitation to produce nanoparticles with small size and narrow particle size distribution. Moreover, tamoxifen-loaded nanoparticles displayed spherical morphology, a positive zeta potential and high drug content (238.6 ± 6.8 µg mL−1) and encapsulation efficiency (80.9 ± 0.4 %). In vitro drug release kinetics showed a burst release at early time points, followed by a sustained release profile controlled by diffusion. MH-b-PS@TMC nanoparticles showed higher cytotoxicity towards MCF-7 cells than free tamoxifen citrate, confirming their effectiveness as a delivery system for administration of lipophilic anticancer drugs.

The influence of microstructure and polymorphic conformer on the shock sensitivity of 1,3,5,7-tetranitro-1,3,5,7-tetrazoctane (HMX)

ABSTRACT The influence on 1,3,5,7-tetranitro-1,3,5,7-tetrazoctane (HMX) shock sensitivity resulting from damage due to phase transition versus that of the polymorphic conformer and crystal lattice change in heated HMX are explored in this work. Samples of class III HMX at 1.24 g/cm3 are shocked in a modified gap test, which yields quantitative, rather than ‘go/no-go,’ results. Microstructural characterization of similarly prepared samples is used to draw conclusions about the primary driver of the difference in sensitivity between pristine -HMX, thermally induced -HMX, and HMX that has spontaneously reverted from -HMX. It is found, surprisingly, that large crystals of HMX incur a slight decrease in shock sensitivity after undergoing -phase transition and/or spontaneous reversion from -HMX. The difference between shock sensitivity results of a significantly smaller HMX particle size distribution are inconclusive using this test configuration. Further testing of the small particle size distribution using a different experimental design that allows lower input pressures may be more useful for comparison. The results of this study indicate that while the increased crack cross-sectional area in HMX crystals drives an increase in impact sensitivity, it drives a decrease in sensitivity in the shock regime for the conditions studied.

Lipase immobilization on a novel class of Zr-MOF/electrospun nanofibrous polymers: Biochemical characterization and efficient biodiesel production

In this study, due to the favorable properties of MOF compounds and fibrous materials, new nanostructures of Zr-MOF/PVP nanofibrous composites were synthesized by electrospinning procedure. The related features of these samples were characterized by relevant analyzes, including SEM, BET surface area analysis, XRD, and FTIR spectroscopy. The final product showed significant properties such as small particle size distribution, large surface area, and high crystallinity. This strategy for producing these nanostructures could lead to new compounds as novel alternative materials for biological applications. Lipase MG10 was successfully immobilized on the mentioned nanofibrous composites and biochemically characterized. The lipase activity of free and immobilized lipases was considered by measuring the absorbance of pNPP (500 μM in 40 mM Tris/HCl buffer, pH 7.8, and 0.01% Triton X100) at 37 °C for 30 min. Different concentrations of glutaraldehyde, different crosslinking times, different times of immobilization, different enzyme loading, and different pH values have been optimized. Results showed that the optimized immobilization condition was achieved in 2.5% glutaraldehyde, after 2 h of crosslinking time, after 6 h immobilization time, using 180 mg protein/g support at pH 9.0. The immobilized enzyme was also totally stable after 180 min incubation at 60 °C. The free enzyme showed the maximum activity at pH 9.0, but the optimal pH of the immobilized lipase was shifted about 1.5 pH units to the alkaline area. The immobilized lipase showed about 2.7 folds (78%) higher stability than the free enzyme at 50 °C. Some divalent metal ions, including Cu2+ (22%), Co2+ (37%), Mg2+ (12%), Hg2+ (11%), and Mn2+ (17%) enhanced the enzyme activity of immobilized enzyme. The maximum biodiesel production (27%) from R. communis oil was obtained after 18 h of incubation by lipase MG10. The immobilized lipase displayed high potency in biodiesel production, about 83% after 12 h of incubation. These results indicated the high potency of Zr-MOF/PVP nanofibrous composites for efficient lipase immobilization.

Synthesis of Different Sizes TiO2 and Photovoltaic Performance in Dye-Sensitized Solar Cells

For more than 2 decades, extensive research has been done in the field of Dye-Sensitized Solar Cells (DSSCs) due to their low cost, easy preparation methodology, less toxicity, and ease of production. In this work, the performance of DSSCs containing different particle sizes is studied. N2-doped TiO2was prepared by the sol-gel method, controlling the particle size through the addition of different H2O/Ti mole ratios R = 0, 20, 30, and 40. The dried samples at 100°C were characterized by X-ray diffraction, Optical Properties, High-Resolution Transmission Electron Microscope, Scanning Electron Microscope, Fourier-Transform Infrared Spectroscopy, N2-Adsorption-Desorption Isotherm, Raman Spectroscopy, and Dynamic Light Scattering (DLS). DLS results show that the size of TiO2decreases as the H2O/TiO2content increases from 0 to 40. It is found that TiO2nanoparticles with smaller particle size distribution has the lowest conversion efficiency of 0.95% with H2O/Ti ratio = 40, and the photoelectrode with higher size has a conversion efficiency of 1.59% for the water-free sample. This could be explained as the larger particles have better dye adsorption, indicating that it has an effective surface area for greater photon absorption and electron-hole generation. The results also indicate that trimodal distribution with larger size also absorbs different wavelengths due to the broad distribution of the particle size.

A study of preparing silver iodide nanocolloid by electrical spark discharge method and its properties

This study employed an electric discharge machine (EDM) and the Electrical Spark Discharge Method (ESDM) to prepare silver iodide nanocolloid (AgINC). Povidone–iodine (PVP-I) was dissolved in deionized water to create a dielectric fluid. Silver material was melted using the high temperature generated by an electric arc, and the peeled-off material was reacted with PVP-I to form AgI nanoparticles (AgINPs). Six discharge pulse wave parameter combinations (Ton–Toff) were employed, and the resultant particle size and suspension of the prepared samples were examined. The results revealed that AgINPs were successfully created using the ESDM. When Ton–Toff was set at 90–90 μs, the zeta potential of the AgINC was − 50.3 mV, indicating excellent suspension stability. The AgINC particle size was 16 nm, verifying that the parameters yielded AgINPs with the smallest particle size distribution and highest zeta potential. Ultraviolet–visible spectrum analyser was performed to analyse the samples, and the spectra indicated that the characteristic wavelength was 420 nm regardless of the Ton–Toff values. X-ray diffraction analysis determined that the AgINPs exhibited two crystal structures, namely β-AgI and Ag. Transmission electron microscopy was performed and revealed that the particles were irregularly shaped and that some of the larger particles had aggregated. The crystal structure was determined to be a mixture of Ag and β-AgI, with a lattice spacing of 0.235 nm and 0.229 nm, respectively. The lattice spacing of the Ag was 0.235 nm. X-ray diffraction analysis indicated that the prepared AgINC were composed of only Ag and I; no additional chemical elements were detected.

Microplastics in the Center of Mediterranean: Comparison of the Two Calabrian Coasts and Distribution from Coastal Areas to the Open Sea.

Plastic is everywhere—increasing evidence suggests that plastic pollution is ubiquitous and persistent in ecosystems worldwide. Microplastic pollution in marine environments is particularly insidious, as small fragmentation can increase interaction with biota and food chain access. Of particular concern is the Mediterranean Sea, which has become a large area of accumulation of plastic debris, including microplastics, whose polymeric composition is still largely unknown. In this study, we analyzed the polymeric composition, particle size distribution, shape, and color of small plastic particles (ranging from 50 to 5000 µm) collected from the sea surface in six stations at the center of the Mediterranean Sea. We also described, for the first time, the different distribution of microplastics from coastal areas up to 12 nautical miles offshore. The microplastic density was 0.13 ± 0.19 particles/m2, with a marked prevalence of smaller particles (73% < 3 mm) and a peak between 1 and 2 mm (34.74%). Microplastics composition analysis showed that the most abundant material was polyethylene (69%), followed by polypropylene (24%). Moreover, we reported a comparison of the two Calabrian coasts providing the first characterization of a great difference in microplastic concentration between the Tyrrhenian and Ionian sides (87% vs. 13%, respectively), probably due to the complex marine and atmospheric circulation, which make the Tyrrhenian side an area of accumulation of materials originating even from faraway places. We demonstrate, for the first time, a great difference in microplastic concentration between Tyrrhenian and Ionian Calabrian coasts, providing a full characterization and highlighting that microplastic pollution is affected by both local release and hydrography of the areas.

Aerosolized Hypertonic Saline Hinders Biofilm Formation to Enhance Antibiotic Susceptibility of Multidrug-Resistant Acinetobacter baumannii.

Limited therapeutic options are available for multidrug-resistant Acinetobacter baumannii (MDR-AB), and the development of effective treatments is urgently needed. The efficacy of four aerosolized antibiotics (gentamicin, amikacin, imipenem, and meropenem) on three different MDR-AB strains was evaluated using hypertonic saline (HS, 7 g/100 mL) as the aerosol carrier. HS aerosol effectively hindered biofilm formation by specific MDR-AB strains. It could also interrupt the swarming dynamics of MDR-AB and the production of extracellular polymeric substances, which are essential for biofilm progression. Biofilms protect the microorganisms from antibiotics. The use of HS aerosol as a carrier resulted in a decreased tolerance to gentamicin and amikacin in the biofilm-rich MDR-AB. Moreover, we tested the aerosol characteristics of antibiotics mixed with HS and saline, and results showed that HS enhanced the inhaled delivery dose with a smaller particle size distribution of the four antibiotics. Our findings demonstrate the potential of using “old” antibiotics with our “new” aerosol carrier, and potentiate an alternative therapeutic strategy to eliminate MDR-AB infections from a biofilm-disruption perspective.

TiO2-Supported Pd as an Efficient and Stable Catalyst for the Mild Hydrotreatment of Tar-Type Compounds.

The mild hydrotreatment of a model mixture of tar-type compounds (i.e., naphthalene, 1-methylnaphthalene, acenaphthylene, and phenanthrene) to produce partially hydrogenated products in the range of C9–C15 was studied over Pd supported on TiO2 possessing different crystalline phases. Pd-based catalysts were prepared and characterized by ICP analysis, XRD, N2 adsorption isotherms, HR-TEM, and NH3-TPD, among others. The hydrotreatment activity and selectivity towards the desired hydrogenated products (i.e., tetralin and others) increased with both the acidity and surface area of the catalyst, along with the presence of small and well distributed Pd nanoparticles. For the selected 1.3 wt% Pd/TiO2 nano catalyst, the operational conditions for maximizing tar conversion were found to be 275 °C, 30 bar of H2, and 0.2 g of catalyst for 7 h. The catalyst revealed remarkable hydrotreatment activity and stability after several reuses with practically no changes in TiO2 structure, quite low carbon deposition, and any Pd leaching detected, thus maintaining both a small Pd particle size and adequate distribution, even after regeneration of the catalyst. Additionally, the Pd/TiO2 nano catalyst was demonstrated to be more active than other commonly used metal/alumina and more selective than metal/USY zeolites in the mild hydrotreatment of tar-type compounds, thus providing an efficient catalytic route for obtaining partially hydrogenated C9–C15 hydrocarbons useful as jet-fuel components or additives (improvers), as well as chemicals and solvents for industrial applications.

Marine plant mediated green synthesis of silver nanoparticles using mangrove Rhizophora stylosa: Effect of variable process and their antibacterial activity

Background: Most natural plants used in the synthesis of silver nanoparticles are limited to marine plants. To carry out applications, colloidal silver nanoparticles (AgNps) should have appropriate properties such as homogeneous shapes, small and narrow particle size distribution, and long time stability. This study aims to determine the effects of a variable process of AgNps mediated mangrove Rhizophora stylosa (RS) leaf extract, and antibacterial activity. Methods: Synthesis of AgNps was carried out by stirring silver nitrate solution with aqueous extract. The characterization of AgNps was carried out using UV-Vis spectrophotometry, X-ray diffraction (XRD), Dynamic Light Scattering (DLS) zetasizer and Transmission Electron Microscopy (TEM). Evaluation of antibacterial activity was carried out on Escherichia coli and Staphylococcus aureus. Reaction conditions such as the concentration of metal ions (0.001 M, 0.005 M, and 0.01 M), extracts (1%, 3%, and 5% v/v), and the reaction time on the size and stability of nanoparticles were also explored. Results: The UV-Vis spectroscopy showed an absorption of colloidal AgNps in a wavelength range of 403–443 nm. TEM analysis showed that as-synthesized AgNps were spherical in shape with a size range of 5–87 nm. The use of 0.001 M and 0.005 M of Ag+ resulted in a smaller diameter than the synthesized AgNps, using 0.01 M Ag+, in the same extract concentration. The range of zeta potential was -24.9 mV to -27.7 mV. The as-synthesized AgNps were stable for more than one month. The XRD analysis showed four peaks, which were attributed to the face centered cubic crystal structure of metallic silver. The results of the silver nanoparticles synthesis showed good activity on Escherichia coli and Staphylococcus aureus, with an inhibition zone between 4.1–7.2 mm. Conclusions: The AgNps synthesized with RS leaf extract, which is a reducing agent, showed good potential as an antibacterial component.

Glutamic acid functionalized casein-calciumferrite magnetic nanosystem based on paired targeting effect for synergistic anticancer therapy

Herein, we developed a multifunctional protein-inorganic hybrid nanocarrier based on superparamagnetic calcium ferrite nanoparticles (CFNP) hybridized with milk protein casein (CN), further functionalized with glutamic acid (GL) and co-loaded with natural anticancer drug thymoquinone (THY). The formulation exhibited good magnetism properties, colloidal stability and smaller particle size distribution with 87.4 % drug encapsulation efficiency. The stimuli responsive structural configuration of the carrier realized high concentrations of the drug at cancer site in response to acidic pH and external magnetic field. Cytotoxicity assay on the U87 cells exhibited superior anti-tumor efficacy of the formulation with 60-fold increase in cytotoxicity of the drug in comparison to free THY, based on the synergistic effects of GL targeting and CFNP incorporation.

Effect of wetting-drying cycle on hydraulic and mechanical properties of cemented paste backfill of the recycled solid wastes

Cemented paste backfill (CPB) technology is beneficial to the recycling of solid wastes and sustainable development in mines. However, the wetting-drying cycle caused by water intrusion and goaf drainage has a great influence on the waterproof and support performance of CPB. In this study, the hydraulic and mechanical properties of CPB samples under wetting-drying cycles were studied by permeability tests, nuclear magnetic resonance (NMR) tests and uniaxial compression tests. The results show that with the increasing number of wetting-drying cycles, the porosity and permeability of CPB samples increase; the porosity and permeability of CPB samples with small particle size distribution and cementing strength are more sensitive to the increasing number of wetting-drying cycles. During the wetting-drying cycles, the uniaxial compressive strength and elastic modulus of CPB samples gradually deteriorate. This effect is more significant for CPB samples with the smaller particle size distribution and cementing strength. According to the periodic destruction of CPB cemented structures caused by wetting-drying cycles, the deterioration process of mechanical properties of CPB samples can be divided into two stages: initial deterioration stage and re-deterioration stage. The microstructure analysis of CPB samples was used to verify the periodic destruction of the cemented structures. Finally, protective measures of CPB were proposed to ensure the stability of CPB. The CPB with large particle size distribution and cementing strength should be adopted. Besides, the filling rate and the monitoring condition of the goaf can be strengthend to reduce and even avoid wetting-drying cycles.

Lithium cobalt phosphate electrode for the simultaneous determination of ascorbic acid, dopamine, and serum uric acid by differential pulse voltammetry

Lithium cobalt phosphate (LCP) was prepared and modified on the surface of glassy carbon electrode (GCE) to fabricate the electrochemical sensor (LCP/GCE) for the simultaneous determination of ascorbic acid (AA), dopamine (DA), and serum uric acid (UA). The homogenous incorporation of carbon improved the conductivity of LCP. Benefiting from the small particle size distribution, LCP/GCE has a large active surface and responds toAA, DA, and UA sensitively and rapidly. For the simultaneous detection with differential pulse voltammetry the anodic peaks of AA, DA, and UA were well-separated and appeared at ~0V, ~0.19V, and ~ 0.33V (vs. Ag/AgCl), respectively. The linear responses toward AA, DA, and UA were in the range 10μM-8.0mM, 10nM-10μM, and 0.020μM-25μM; the detection limits were estimated to be 8.10μM, 7.50nM, and 22.7nM (S/N = 3), respectively. The excellent selectivity and reproducibility of LCP/GCE enable serum UA to be detected without the interference of AA and DA. The recoveries of DA and AA in the serum sample were in the range 95 to 111%. The results indicate thatLCP has the potential to be developed as the sensing devices to be applied to in vitro diagnosis. The lithium-ion battery cathodic material, LCP with the excellent adsorption and catalytic behavior, was utilized to fabricate the electrochemical sensor for the sensitive and simultaneous detection of AA, DA, and UA, which achieved the low detection limits and the wide concentration ranges. LCP/GCE can be used for the quantitative detection of serum UA without the interference of DA and AA. In addition, the recoveries of DA and AA in human serum were satisfactory, which illustrate the reliability of LCP/GCE to be applied to in vitro diagnosis.

Research on the Formation Mechanism of Seepage Channels in Broken Rock Mass under the effects of Particle Migration

Seepage within broken rock mass widely exists in geotechnical engineerings, such as railways, slopes, dam foundations and mining. Seepage is often accompanied by particle migration, which usually cause structural instability and water inrush disasters. In order to study the formation mechanism of seepage channels in the brocken rock mass under the effects of particle migration, a series of seepage tests were designed on broken red sandstone. The effects of pore pressure and particle size distribution (PSD) on particle migration and porosity evolution were studied. The main conclusions are as follows: 1) By observing the particles collected during the seepage process, particles with size range of 0-2 mm, 2-5 mm and 5-8 mm appear in sequence, which means that with the formation of seepage channels, large size of rock particles can pass through the broken rock mass. 2) The cumulative mass of migrating particle increases with the increase of pore pressure and decrease of PSD; with the increasing duration of migration process, the pore pressure and PSD decrease. 3) The peak value of porosity increases with the increase of pore pressure and decrease of PSD. According to above results, the seepage channels of the samples with smaller PSD and larger pore pressure are wider. Besides, the formation speed of seepage channels is larger in sample under higher pore perssure. These can explain the higher risk of geological disasters (i.e., water inrush and structural instability) in broken rock mass within higher pore pressure and smaller PSD.