Porous Rods Research Articles

MWCNT reinforced bone like calcium phosphate—Hydroxyapatite composite coating developed through pulsed electrodeposition with varying amount of apatite phase and crystallinity to promote superior osteoconduction, cytocompatibility and corrosion protection performance compared to bare metallic implant surface

Inconsistent growth of tissues and poor osteoconduction performance on the metallic implant surfaces due to variation of surface energy are major contributing factors for failure of most metallic implant on account of lack of stronger attachment with surrounding bone or tissues. In this study, composite coating of hydroxyapatite, calcium hydrogen phosphate and MWCNT was developed on SS316 surface with varying amount of calcium phosphate-hydroxyapatite phase and crystallinity by pulsed electrodeposition. TEM study revealed that the MWCNTs were bonded strongly with the in situ deposition phases and thus act as reinforcement in the deposited coating similar to the collagen fiber in natural bone structure. Presence of MWCNT reinforcement increased the overall coating modulus of elasticity in the range of 6–10GPa similar to that of natural bone. Different coating surfaces with varied amount of phase and crystallinity exhibits altogether different phenomena and growth geometry of apatite formation during osteoconduction period under contact with SBF. Coatings with highest amount of hydroxyapatite phase exhibit formation of porous spherical (~1μm) and rod like (~600nm) scaffold structure along with presence of nanopores (~100nm) all along the contact surfaces. Cell proliferation study indicated uniform and fast spreading of cells over the coating surfaces as compared to bare metallic implant. EIS study illustrated five times high corrosion resistance capability along with formation of passivation layer under contact with SBF for coating comes with 66% of hydroxyapatite phase.

Experimental Investigation and Three-Dimensional Numerical Analysis of Ferroconvection Through Horizontal Tube Under Magnetic Field of Fixed Parallel Magnet Bars

This study includes experimental and three-dimensional numerical analysis of conjugate steady-state laminar forced ferroconvection of Newtonian incompressible ferrofluid through a horizontal circular pipe under constant heat flux and in presence of transverse magnetic field. The magnetic field was applied by two fixed parallel magnet bars at the beginning of the tube. To validate the thermohydrodynamic characteristics obtained by numerical results, appropriate experimental setup with accurate instrumentations was conducted. Based on presence and absence of porous media and solid rod inside of pipe, six conditions were compared for quantifying the heat transfer enhancement and effectiveness. Governing equations were discretized by finite volume method (FVM) and solved using the semi-implicit method for pressure linked equations (SIMPLE) algorithm and computational fluid dynamic (CFD) techniques. It was found that magnetic field, porous media, and solid rod increase heat transfer and pressure loss in the pipe such that solid rod has the best effect on heat transfer and worst effect on effectiveness.

Porous Al-doped ZnO rods with selective adsorption properties

Al-doped ZnO (ZnO:Al) rods with Al doping varying from 0 to 20% were successfully prepared via a solvothermal method. ZnO:Al rods exhibit the hexagonal wurtzite crystalline structure and their length were found to decrease from 127 to 12nm when increasing the dopant percentage from 0 to 20%. Simultaneously, their specific surface area increased from ca. 21 to 82m2/g. ZnO:Al (20%) rods exhibit high adsorption capability towards some negatively charged dyes like Orange II, Acid red 88 or Alizarin, which was attributed to the high specific surface of ZnO:Al rods and to the defects induced by the Al doping as demonstrated by XRD and Raman spectroscopy.

Mechanical properties of zirconia core-shell rods with porous core and dense shell prepared by thermoplastic co-extrusion

Bi-layered zirconia rods of core-shell geometry with a porous core of different core porosities and a dense shell of various shell thicknesses were investigated. Core-shell structures were successfully prepared by thermoplastic co-extrusion of assembled feedrods. For comparison, non-layered rods with different porosities and tubes were also prepared. Mechanical properties of sintered core-shell rods were determined and compared with the properties of non-layered rods and tubes. Increasing porosity in the core of the core-shell rods decreased Young’s modulus and the dense shell improved the fracture resistance of the core-shell rods against bending loading. The fracture force of core-shell rods was in all cases considerably higher than the fracture force of non-layered porous rods or tubes with the same Young’s modulus. The fracture behaviour of core-shell rods and tubes was analysed and correlated with the calculated stress distribution in these structures. The principle of the core-shell concept was described and discussed.

Polymer-coated bioactive glass S53P4 increases VEGF and TNF expression in an induced membrane model in vivo

The two-stage induced-membrane technique for treatment of large bone defects has become popular among orthopedic surgeons. In the first operation, the bone defect is filled with poly(methyl methacrylate) (PMMA), which is intended to produce a membrane around the implant. In the second operation, PMMA is replaced with autograft or allograft bone. Bioactive glasses (BAGs) are bone substitutes with bone-stimulating and angiogenetic properties. The aim of our study was to evaluate the inductive vascular capacity of BAG-S53P4 and poly(lactide-co-glycolide) (PLGA)-coated BAG-S53P4 for potential use as bone substitutes in a single-stage induced-membrane technique. Sintered porous rods of BAG-S53P4, PLGA-coated BAG-S53P4 and PMMA were implanted in the femur of 36 rabbits for 2, 4 and 8 weeks. The expression of vascular endothelial growth factor (VEGF) and tumor necrosis factor alpha (TNF) in the induced membranes of implanted materials was analyzed with real-time quantitative polymerase chain reaction and compared with histology. Both uncoated BAG-S53P4 and PLGA-coated BAG-S53P4 increase expression of VEGF and TNF, resulting in higher amounts of capillary beds, compared with the lower expression of VEGF and less capillary beads observed for negative control and PMMA samples. A significantly higher expression of VEGF was observed for PLGA-coated BAG-S53P4 than for PMMA at 8 weeks (p < 0.036). VEGF and TNF expression in the induced membrane of BAG-S53P4 and PLGA-coated BAG-S53P4 is equal or superior to PMMA, the “gold standard” material used in the induced-membrane technique. Furthermore, the VEGF and TNF expression for PLGA-coated BAG-S53P4 increased during follow-up.

A convenient approach for the determination of multiple trace BPs using an in-syringe-assisted solid phase microextraction system packed with elastic spongy graphene rods coupled with HPLC

An elastic cylindrical three-dimensional porous spongy graphene rod (3D-PSGR) was synthesized by a facile one-step hydrothermal method and applied in a syringe system as a solid phase adsorbent for the extraction of nine trace bisphenol analogs (BPs) from environmental samples.

Porous silica/TiO2 Nanocomposite for Collective Adsorption and Degradation Functionalities

The performance of photocatalytic oxidation of volatile organic compounds (VOCs) generally depends on two properties: VOCs adsorption abilities as well as the degradation functionalities. In this work, a hybrid system of silicon dioxide (SiO2) and titanium dioxide (TiO2) was synthesized for enhanced degradation functionalities. The reasons for high demand of porous silica in the applications are attributed to the low cost, high surface area and the feasibility of obtaining various pore sizes. A simple aqueous-phase method was used to synthesize different structures of porous silica for VOC adsorption capabilities. Porous SiO2 rods of the highest surface area (1238 m2g-1) was chosen to incorporate with the TiO2 sheets for enhanced degradation. Hydrothermal TiO2 growth on SiO2 was optimized by varying the amount of precursors used. The synthesized materials were characterized with scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and photocatalytic performance for VOC degradation under UV-LED illumination. The optimized SiO2rods@TiO2 sample showed enhancement of degrading up to 60 % in 120 min of degradation. Furthermore, CuO acts as an effective co-catalyst to enhance charge separation and the degradation performance was improved by loading the SiO2rods@TiO2 sample with CuO. A loading amount of 5% was found to be the optimum for enhanced degradation performance.

Transition Metal (Fe, Co, Ni) Oxide Micro/Nanostructures: Phase, Morphology, and Decomposition of Precursors.

Transition metal oxides nano/micro structures including α-Fe₂O₃, Fe₃O₄, Co3O₄ and NiO were fabricated through controlling the decomposition of corresponding precursors. It is found that the morphology and phase composition of iron oxide depended strongly on heat-treatment approaches and conditions of the precursor. Furthermore, the iron oxide precursor created from FeCl₂, FeCl₃ and N₂H₄ in N,N-dimethylformamide solution with polyvinyl pyrrolidone via a hydrothermal synthesis was an unknown phase according to the X-ray diffraction (XRD) data base. Fe₃O4 nanoparticles (NPs) with several nanometers were obtained when the rod precursor was dissolved in water at room temperature, In contrast, when the precursor was calcined in an air atmosphere, porous α-Fe₂O₃ rods were acquired. Interestingly, the rod precursor can be transformed into perfect Fe₃O₄ rhombic dodecahedrons in the case of keeping the solvothermal reaction for a long time. For comparison, cobalt and nickel oxide precursors were prepared. After calcination, porous rod-like Co₃O₄ crystals comprised of tiny particles and flower-like NiO hierarchical structures comprised of porous sheets were obtained.

Fabrication of one-dimensional Bi2O3–Bi14MoO24heterojunction photocatalysts with high interface quality

Novel, one-dimensional Bi2O3–Bi14MoO24 heterostructures with high interface quality were synthesized by high temperature calcination of Bi2MoO6–Bi(OHC2O4)·2H2O precursors in air at 400 °C for 2 h. Bi14MoO24 grew on the Bi2O3 porous rods by crystallographic-oriented epitaxial growth, which increased the interface quality and then provided the smallest penetration barrier for electron–hole pair transfer between Bi2O3–Bi14MoO24 interfaces. The photocatalytic activity of the as-prepared products was evaluated by the degradation of methyl orange (MO) and phenol under solar/visible light irradiation. The results show that Bi2O3–Bi14MoO24 heterostructures display higher photocatalytic activity than that of the pure phase Bi2O3 and Bi14MoO24, and 100% phenol (10 mg L−1) can be degraded in 80 min under visible light irradiation using the Bi2O3–Bi14MoO24 (DS-2) heterostructure as photocatalyst. This enhanced photocatalytic performance is ascribed to the synergistic effect of the suitable band alignment of the Bi2O3 and Bi14MoO24, high interface quality and one-dimensionally ordered nanostructure. Radical scavenger experiments proved that the photogenerated holes and ˙O2− play key roles during the photodegradation process. This work offers an effective route to the design and fabrication of the junction structures with high interface quality for photocatalytic applications.

Controlled Synthesis and Electrocatalytic Performance of Porous Nickel Cobaltite Rods

以NiCl 2 ·6H 2 O, CoCl 2 ·6H 2 O和草酸为原料, 利用氨水为配位剂和溶液pH调节剂, 通过配位共沉淀–热分解法制备了棒状多孔NiCo 2 O 4 粉末, 采用X射线衍射、扫描电镜、透射电镜以及比表面积仪对前驱体和NiCo 2 O 4 粉末的形貌和结构进行了表征, 考察了溶液pH对前驱体粉末形貌和分散性的影响; 采用循环伏安法和计时电流法研究了乙醇在棒状多孔NiCo 2 O 4 粉末修饰的玻碳电极上的电催化性能。结果表明: 前驱体的形貌与溶液的pH有关, 热分解得到的NiCo 2 O 4 粉末继承了前驱体形貌, 呈多孔棒状, 比表面积为89 m 2 /g, 平均孔径为12.56 nm。该粉末对乙醇具有良好的电催化活性, 氧化峰电流与乙醇浓度、扫速的平方根均呈直线关系, 表明棒状多孔NiCo 2 O 4 粉末对乙醇的催化反应机理为扩散控制。

Batteries: High Sulfur Loading in Hierarchical Porous Carbon Rods Constructed by Vertically Oriented Porous Graphene‐Like Nanosheets for Li‐S Batteries (Adv. Funct. Mater. 48/2016)

Batteries: High Sulfur Loading in Hierarchical Porous Carbon Rods Constructed by Vertically Oriented Porous Graphene‐Like Nanosheets for Li‐S Batteries (Adv. Funct. Mater. 48/2016)

Effects of different porous beds on turbulent characteristics in an open channel above the porous bed

An analysis of the turbulent characteristics of the flow in an open channel with horizontal porous beds using two-dimensional (2D) Particle Image Velocimetry (PIV) is presented. Hydraulic characteristics such as velocity distributions, turbulent intensities and Reynolds stress are investigated at a fine resolution using the PIV. Experiments were carried out, with four types of porous bed with the same porosity ε=0.70 and the same porous thickness (3cm): (a) porous filter, (b) rods bundle, (c) grass vegetation and (d) gravel bed. Turbulent characteristics are measured above the porous bed for the same different water heights (h΄=3, 5, 7 and 9cm) and for the same slope S=1.5‰. Main emphasis is given to the effects of relative porous thickness s΄/h (s΄=porous thickness, h=total flow height) on the flow characteristics over the porous beds. The relative thickness s΄/h varies between 0.250 and 0.500. The discharge ranges between 3.0 and 24.6 lt/s. Measurements of mean velocity and turbulence characteristics indicate the effects of the bed material used on the flow characteristics. The presence of rods bundle influences with different way the turbulent characteristics of the flow as regards the other porous beds.

Synthesis of one-dimensional Bi2O3-Bi2O2.33 heterojunctions with high interface quality for enhanced visible light photocatalysis in degradation of high-concentration phenol and MO dyes

One-dimensional (1D) Bi2O3-Bi2O2.33 heterostructures were synthesized by calcining Bi2O2CO3-Bi(OHC2O4)·2H2O precursors. Ultrathin Bi2O2.33 nanosheets were uniformly patched onto the porous Bi2O3 rod with well-matched lattice fringes, which increased the interface quality and then provided the smallest penetration barrier for electron-hole pairs transfer between Bi2O3-Bi2O2.33 interfaces. The photocatalytic performance of the obtained products was evaluated by the degradation of high-concentration methyl orange (MO) and phenol under solar/visible light irradiation. The results show that Bi2O3-Bi2O2.33 heterostructure displays higher photocatalytic activity than pure phase Bi2O3 and Bi2O2.33, and more encouragingly, 30mg/L of MO (or phenol) can be completely degraded in 60min under visible light irradiation using Bi2O3-Bi2O2.33 (S2) heterostructure as photocatalyst. This enhanced photocatalytic performance is ascribed to the synergistic effect of the suitable band alignment of the Bi2O3 and Bi2O2.33, high interface quality beween Bi2O3 and Bi2O2.33 junctions and one-dimensional ordered nanostructure. This work would offer a novel route to design and fabrication of junction structures with high interface quality for photocatalytic applications.

Influence of permeable bed and channel width on turbulent characteristics in inclined open channel flows

For the investigation of the influence of the kind of the different permeable bed and channel width in inclined open channels, a series of laboratory experiments were performed. Experiments were conducted in two channels with different widths. The permeable bed is simulated using four different types of porous bed: (a) porous filters, (b) rods bundle, (c) grass vegetation, and (d) gravel bed. All the permeable beds have the same thickness and the same porosity. These conditions are similar to environmental flows. Laboratory experiments were used for the calculation of the turbulent velocity profiles and the turbulent characteristics of the flow (turbulent intensities and turbulent shear stresses). The measurements were obtained using a two-dimensional Particle Image Velocimetry. Measurements of velocity were taken for inclined channels for different slopes S and for the same three different heights h′ over the permeable bed. The results indicate that the presence of different kinds of the permeable bed and the different widths of the channel influence the turbulent characteristics of the flow.

Coupling effect between ultra-small Mn3O4 nanoparticles and porous carbon microrods for hybrid supercapacitors

Hybrid supercapacitor, which is an energy storage device that combines a low-energy/fast double-layer electrode and a high-energy/sluggish faradaic redox electrode, could realize further gains in energy/power density if the capacity and rate gaps of the two electrodes are properly balanced. Herein, a microrod-like architecture that incorporates Mn3O4 nanoparticles on/in highly porous carbon rods (PCR) scaffold (denoted as Mn-PCR composite) is designed for this purpose. The optimized Mn-PCR composite exhibits large Li-ion storage capacity and fast charge/discharge rate, mainly stemming from its distinct microrod-like architecture and porous structure. We then employ Mn-PCR composite as the anode and PCR as the cathode to fabricate a hybrid supercapacitor, which yields an ultrahigh energy density of 174Whkg−1 at 200Wkg−1 and retains 74.5Whkg−1 at a high power density of 10kWkg−1.

High Sulfur Loading in Hierarchical Porous Carbon Rods Constructed by Vertically Oriented Porous Graphene‐Like Nanosheets for Li‐S Batteries

The utilization of porous carbon frameworks as hosts for sulfur loading is an important theme in current Li‐S battery research. Unfortunately, the high loading of insulating sulfur often leads to low specific capacities, poor rate properties, and rapid capacity loss. To address this challenge, a facile templating route to fabricate a novel host material, hierarchical porous carbon rods constructed by vertically oriented porous graphene‐like nanosheets (HPCR) is presented. With a high specific surface area, ultralarge pore volume, hierarchical porous structures, and ideal ion transfer pathways, HPCR is a promising candidate for high sulfur loading. When used as the active material for a sulfur cathode, the HPCR‐S composite with 78.9 wt% sulfur exhibits excellent rate performance (646 mAh g−1sulfur at 5 C) and cycling stability (700 mAh g−1sulfur after 300 cycles at 1 C). Even with a sulfur content of 88.8 wt%, the HPCR‐S composite, without any additional protective polymer coating, still delivers a good rate performance (545 mAh g−1sulfur at 3 C) and cycling stability (632 mAh g−1sulfur after 200 cycles at 1 C). More importantly, the high sulfur loading (88.8 wt%) ensures that the HPCR‐S composite has a high energy density (880 mAh cm−3cathode after 200 cycles at 1 C).

Controllable synthesis and enhanced microwave absorbing properties of Fe3O4/NiFe2O4/Ni heterostructure porous rods

We developed a coordinated self-assembly/precipitate transfer/sintering method that allows the controllable synthesis of Fe3O4/NiFe2O4/Ni heterostructure porous rods (HPRs). A series of characterizations confirms that changing [Ni2+] can effectively control the crystal size, internal strain, composition, textural characteristics, and properties of HPRs. Molar percentages of Ni and NiFe2O4 in HPRs increase with [Ni2+] in various Boltzmann function modes. Saturation magnetization Ms and coercivity Hc show U-shaped change trends because of crystal size, composition, and interface magnetic coupling. High magnetic loss is maintained after decorating NiFe2O4 and Ni on the surface of Fe3O4 PRs. Controlling the NiFe2O4 interface layers and Ni content can improve impedance matching and dielectric losses, thereby leading to lighter weight, stronger absorption, and broader absorption band of Fe3O4/NiFe2O4/Ni HPRs than Fe3O4 PRs. An optimum EM wave absorbing property was exhibited by Fe3O4/NiFe2O4/Ni HPRs formed at [Ni2+]=0.05M. The maximum reflection loss (RL) reaches −58.4dB at 13.68GHz, which corresponds to a 2.1mm matching thickness. The absorbing bandwidth (RL≤−20dB) reaches 14.4GHz with the sample thickness at 1.6–2.4 and 2.8–10.0mm. These excellent properties verify that Fe3O4/NiFe2O4/Ni HPRs are promising candidates for new and effective absorptive materials.

A simple fabrication for sulfur doped graphitic carbon nitride porous rods with excellent photocatalytic activity degrading RhB dye

Constructing special nanostructures with large surface areas and tuning the band gap by element doping are efficient strategies to enhance the photocatalytic activity of semiconductor materials. Here we combined both strategies in one material to form sulfur-doped graphitic carbon nitride porous rods (S-pg-C3N4) in one pot by simply pyrolysis of the melamine-trithiocyanuric acid complex with different temperatures. The samples were characterized by XRD, FT-IR, and elemental analysis; nitrogen adsorption isotherms, SEM and TEM images; and UV–vis DRS and photoluminescence spectra. Characterizations showed that S-pg-C3N4 possessed porous rod structure with a larger surface area (20–52m2/g) than that of bulk g-C3N4, and the surface area of the S-pg-C3N4 samples increased with the increase of heating temperature. Meanwhile, the trace sulfur remained in the framework of g-C3N4 formed sulfur doped g-C3N4, and the visible light absorption edge of the S-pg-C3N4 was extended, corresponding to a narrowed band gap. As a result, the S-pg-C3N4 samples exhibited an enhanced physical adsorption and photocatalytic activity in the degradation of Rhodamine B dye under visible light.

Shuttle‐like Porous Carbon Rods from Carbonized Metal–Organic Frameworks for High‐Performance Capacitive Deionization

AbstractOne of the most challenging issues in developing capacitive deionization (CDI) technologies is the rational design and synthesis of active electrode materials with favorable morphologies and high surface areas. Here, for the first time, shuttle‐like porous carbon rods (sPCRs) were prepared through a high temperature pyrolysis step and a subsequent etching step by using rod‐like metal–organic frameworks, MIL‐88 (Fe), as the precursor. The correlation between the carbonization temperature of sPCRs and their electrosorption performance was investigated, and it was found that, owing to their unique shuttle‐like rod structure and high specific surface area, sPCRs obtained at 900 °C exhibit a superior electrosorption capacity of 16.2 mg g−1 with excellent cycling stability, showing that sPCRs could be a promising electrode material for highly efficient CDI.

Facile synthesis of porous iron oxide rods coated with carbon as anode of high energy density lithium ion battery

A novel composite of Fe2O3 and carbon (Fe2O3@C) was synthesized hydrothermally without using any template and evaluated as anode of high energy density lithium ion battery. Physical characterizations, from XRD, FESEM, TEM, HRTEM, TGA, XPS, and Raman spectroscopy, demonstrate that the resulting Fe2O3@C takes a morphology of porous rods, which is composed of 100nm Fe2O3 particles that are coated uniformly with a layer of amorphous carbon. Charge/discharge tests indicate that the resulting Fe2O3@C delivers a reversible discharge capacity of 907mAhg−1 at 100mAg−1 and 420mAhg−1 at 5000mAg−1, and maintains a discharge capacity of 639mAhg−1 after 300 cycles at 500mAg−1. These performances can be attributed to the unique configuration of the Fe2O3@C rods. The nanoparticles in the rods shorten the path of lithium ion diffusion and increase the reaction sites for lithium insertion/extraction, the pores in the rods provide space to accommodate the volume change yielded during charge/discharge process and the carbon coating preserves the structural integrity of Fe2O3.