Smaller Pore Volume Research Articles

Application of Polystyrene Nanofiber in Detection of Anxiety-Related Bio-Marker Cortisol

This work aimed to explore the correlation between plasma cortisol level and the occurrence of anxiety through the polystyrene (PS) nano-fiber solid phase extraction technology. The PS nano-fibers were prepared, and its characterization was performed to detect its adsorption selectivity and blood compatibility. 32 anxiety patients treated in the hospital were recruited as the research subjects, with another 35 mentally healthy people as controls. The Hamilton Anxiety (HAMA) Scale, Symptom checklist-90 (SCL-90) scale, and Eysenck personality questionnaire (EPQ) were used to analyze the anxiety degree, psychological disorder degree, and personality of the two groups. The plasma cortisol level was detected by PS nano-fiber solid phase extraction technology. Finally, the Pearson correlation test was performed to analyze the correlation between the plasma cortisol level and the scores of HAMA scale, SCL-90 scale, and EPQ scale in anxiety patients. It was revealed that the HAMA scale and SCL-90 scale scores of anxiety patients were superior to those of healthy subjects (P < 0.05). The “neuroticism” factor score in EPQ were obviously higher than that of healthy subjects (P < 0.05). The diameter of the prepared PS nano-fiber was within 200~900 nm, with a small specific surface area (BET), pore volume, and pore size, and the cellular structure was noted on the fiber surface. The PS nano-fiber demonstrated relatively good adsorption performance for benzene hydrocarbon compounds and had excellent anti-protein adsorption capacity. It was found that the plasma cortisol level of anxiety patients was higher than that of healthy subjects (P < 0.05), and the plasma cortisol level was positively correlated with HAMA scale, SCL-90 scale, and EPQ scale scores (r = 0.996, 0.993, and 0.971, respectively; P < 0.05). In conclusion, the PS nano-fiber solid phase extraction technology can be applied to identify the plasma cortisol level, which was with a good anti-interference property. An increased plasma cortisol level can be used as an indicator for auxiliary diagnosis of anxiety.

Mechanical performances and microstructural characteristics of reactive MgO-carbonated silt subjected to freezing-thawing cycles

The characteristics of reactive magnesia (MgO)-carbonated silt in respect to long-term stability have not been well understood in severely cold climate despite the usage of reactive MgO in enhancing the engineering performances. Under the binder content of 15% and initial water content of 25%, MgO-admixed silt specimens were carbonized for 3 h and 6 h and then subjected to different numbers of freezing-thawing (F-T) cycles. After different F-T cycles, the physico-mechanical properties of MgO- carbonated silt were analyzed in comparison with Portland cement (PC)-stabilized silt through physical and unconfined compression tests. Besides, a series of micro tests on MgO-carbonated specimens was performed including X-ray diffraction (XRD), scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) tests. The results demonstrate that both mass change ratio and moisture content of carbonated/stabilized silt decrease, and these values of MgO-carbonated silt are significantly lower while the density is higher compared to PC-stabilized silt. The strengths and moduli of MgO-carbonated silt are still two times higher than those of PC-stabilized specimens and the strength change ratio of keeps above 0.8 after F-T cycles. There is no visible transformation between nesquehonite and dypingite/hydromagnesite, although the XRD peaks of nesquehonite decrease and the bonding and filling effects weaken slightly. After 6 and 10 F-T cycles, the pore-size characteristics changed from a unimodal distribution to a three-peak and bimodal distribution, respectively. The total, macro and large pore volumes increase obviously while the medium and small pore volumes decrease except for intra-aggregate pore. The findings show better F-T durability of MgO-carbonated silt, which would be helpful for facilitating the application of MgO carbonation in the soil treatment. • Innovative carbonation technique based on reactive MgO and CO 2 is used in soil reinforcement. • The engineering performances of MgO-carbonated silt are much better than those of PC-stabilized silt. • There is no phase transformation but distinct micro-pore evolution detected after freezing-thawing cycles. • MgO-carbonated silt has a higher durability against freezing-thawing cycles. • A microstructure mechanism of MgO-carbonated silt is suggested schematically.

Permeability characteristics and structural evolution of compacted loess under different dry densities and wetting-drying cycles.

Permeability characteristics of compacted loess is always an important topic in soil mechanics and geotechnical engineering. This study explored the permeability characteristics of compacted loess under different dry densities and wetting-drying cycles, and found that as the dry density increases, the compacted loess surface became denser, the saturation permeability coefficient and saturation infiltration rate decreased. However, the wetting-drying cycle presented the opposite result. Meanwhile, the evolution of the microstructure was investigated by Scanning Electron Microscope (SEM) and Nuclear Magnetic Resonance (NMR) to explain the change of its permeability characteristics. The size of compacted loess aggregates was quantitatively analyzed by Image-Pro Plus (IPP) software. It showed that the size of compacted loess aggregates for different dry densities were concentrated from 10–100 μm, occupying 65.0%, 58.19%, and 51.64% of the total aggregates area respectively. And the interesting finding was that the area occupied by 10–50 μm aggregates remained basically unchanged with the number of wetting-drying cycles increasing. Therefore, the size of 10–50 μm aggregates represented the transition zone of compacted loess. NMR analyses revealed that with increasing dry density, the volume of macropores in the compacted loess rapidly decreased, the volume of mesopores and small pores increased. Meanwhile, the change in micropores was relatively small. The pore volume of the compacted loess after three wetting-drying cycles increased by 8.56%, 8.61%, and 6.15%, respectively. The proportion of macropores in the total pore volume shows the most drastic change. Variations in aggregate size and connection relationships made it easier to form overhead structures between aggregates, and the increased of macropore volume will form more water channels. Therefore, the change in permeability characteristics of compacted loess is determined by aggregate size, loess surface morphology, and the total pore volume occupied by macropores.

Thiophene-based MOFs for iodine capture: Effect of pore structures and interaction mechanism

The effective capture of radioiodine is vital to the development of the nuclear industry and environmental protection. Metal-organic frameworks (MOFs) are promising adsorbents for iodine vapor due to the versatile metal nodes and linkers, as well as tunable pore structures. Here, five thiophene-based metal–organic frameworks with different pore geometries were investigated for their iodine adsorption properties, and the relationship between the pore structures and iodine adsorption capacities is examined. DUT-68 adsorbs a large amount of iodine (1081 mg/g), which is 28% higher than that of the homologous DUT-67 (843 mg/g), because its large cage could provide more space for the packing of molecular iodine in the middle of the pore. The MIL-53-TDC(In) with 1D straight-through pore channels only has an iodine capacity of 660 mg/g, due to its small pore volume and little confinement effect. Meanwhile, the In-DTC and Ho-DTC, with smaller pore sizes than the kinetic diameter of iodine molecules, exhibit almost no iodine adsorption properties. Raman, fluorescence, XPS spectra and DFT calculation confirm the strong charge transfer effect from thiophene linkers to trapped iodine. DFT calculation also provides quantitative adsorption energy of −44.5 kJ/mol between one iodine molecule and one thiophene group linked with Zr nodes, higher than that of thiophene groups linked with In nodes. This work may motivate the topology-directed design of MOFs for iodine capture with optimized pore structures, metal nodes and linkers to enhance the adsorption performance.

Fe–Ti bimetal oxide adsorbent for removing low concentration H2S at room temperature

ABSTRACT Herein, a series of Fe–Ti bimetal oxide adsorbents were prepared by reduction–co-precipitation method, and their performance in removing low concentration H2S at room temperature was investigated. The adsorbents were characterized by X-Ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Ultraviolet Visible diffuse reflectance spectroscopy (UV–Vis-DRS), X-Ray photoelectron spectroscopy (XPS) and N2 adsorption–desorption. The results showed that the addition of Ti increased the specific surface area, pore volume and small oligomeric Fe2O3 of ferrihydrite. When the Fe/Ti molar ratio was 8:1, Fe–Ti bimetal oxide formed a large amount of oligomeric Fe2O3, and its specific surface area and pore volume reached 344.99 m2/g and 0.34 cm3/g, respectively. At this time, Fe–Ti bimetal oxide exhibited the highest breakthrough sulfur capacity of 222.8 mg/g. High temperature calcination caused Fe–Ti bimetal oxide to form small specific surface area and pore volume, and produced crystalline α-Fe2O3. And the breakthrough sulfur capacity of Fe–Ti bimetal oxide decreased with the increasing calcination temperature. In addition, the desulfurization process conformed to the unreacted shrinking nucleus model.

Fractal characteristics of shale pore structure and its influence on seepage flow.

The migration law of shale gas has a significant influence on the seepage characteristics of shale, and the flow of the gas is closely related to the pore structure. To explore the influence of shale pore parameters on permeability in different diffusion zones, the pore structure of the shale in the Niutitang Formation in Guizhou, China, was analysed based on liquid nitrogen adsorption experiments and nuclear magnetic resonance experiments. The relationship among fractal dimension, organic carbon content (TOC) and BET-specific surface area was analysed based on the fractal dimension of shale pores calculated using the Frenkel–Halsey–Hill model. Shale permeability was calculated using the Knudsen number (Kn) and permeability equation, and the influence of the fractal dimension and porosity in different diffusion zones on shale permeability was analysed. Previous studies have shown that: (i) the pores of shale in the Niutitang Formation, Guizhou are mainly distributed within 1–100 nm, with a small total pore volume per unit mass, average pore diameter, large BET specific surface area and porosity; (ii) fractal dimension has a negative correlation with average pore diameter and TOC content and a quadratic relationship with BET specific surface area; and (iii) permeability has a positive correlation with Kn, porosity and fractal dimension. In the transitional diffusion zone, fractal dimension and porosity have a significant impact on permeability. In the Knudsen diffusion zone, porosity has no obvious effect on permeability. The methodologies and results presented will enable more accurate characterization of the complexity of pore structures of porous media and allow further understanding of the seepage law of shale gas.

Effects of Clay Content on Pore Structure Characteristics of Marine Soft Soil

This study investigates the pore structure characteristics of a marine soft soil of the Beibu Gulf, Guangxi Province, China and its variation with clay content. Pore-size distribution was measured by Mercury intrusion porosimetry (MIP) and analyzed based on fractal theory. The analysis of the results relies on the distinction of several types of pores: micropores, small pores, mesopores and macropores, separated by the critical pore diameters of 0.02 μm, 0.18 μm and 0.78 μm, respectively. Mesopores and small pores were dominant, accounting for more than 75% of the total pore volume. Small pore volume increases with clay content at the expense of the mesopore volume. Between 22.31% and 32.31% clay, the connectivity of pores improves with clay content, while the tortuosity of pores increases from 22.31% to 32.31% of clay and then decreases between 32.31% and 37.31% clay. Marine soft soil in the Beibu Gulf is characterized by multiple fractal dimensions. Macropores had a large (close to 3) fractal dimension, independent of clay content. Mesopores and small pores had a smaller fractal dimension comprised between 2.1 and 2.4, while the fractal dimension of micropores did not exceed 1.5. The fractal dimension of mesopores and micropores are influenced significantly by the clay content. The study of the porosity of the marine soft soil of the Beibu Gulf could serve as a useful basis for the prediction of its hydraulic properties.

Two-dimensional Fe2O3 nanosheets as adsorbent for the removal of Pb(II) from aqueous solution

Two dimensional (2D) metal oxide are expected to be better adsorbents for heavy metal ions than their other low dimensional counterparts. In this work, non-layered 2D Fe2O3 nanosheets were synthesized by a simple combustion method and tested for Pb(II) removal from aqueous solution. The 2D Fe2O3 nanosheets exhibited high crystallinity and purity as confirmed by powder x-ray diffraction. As revealed by scanning electron microscope (SEM) and transmission electron microscope (TEM), the nanosheets with lateral size up to hundreds of microns that made it easy to be recollected after water treatment. The results of XRD and TEM indicated that the nanosheets showed preferentially exposedsurfaces of (100), which has strong affinity for Pb(II). The nanosheets exhibited a moderate specific surface area of 12.19 m2/g with a small pore volume of 0.034 mL/g. The nanosheets exhibited excellent adsorption performance for Pb(II) in pH range from 3.0 to 6.0. The adsorption of Pb(II) conformed to the Langmuir isotherm model with the theoretical maximum adsorption capacity of Pb(II) estimated to be 436.83 mg/g. Kinetics study indicated that the adsorption process followed pseudo-second-order kinetics model. Based on the X-ray photoelectron spectroscopy and FTIR results of the nanosheets before and after Pb(II) adsorption, the adsorption of Pb(II) was dominated by the surface complexation and ion exchange of Pb(II) ions with surface hydroxyl groups. Given the low preparation cost and the excellent adsorption capacity, the non-layered 2D Fe2O3 nanosheets holds great potential as adsorbent for Pb(II) removal.

Multiscale characteristics of the wetting deformation of Malan loess in the Yan’an area, China

Loess is prone to collapse upon wetting due to its open metastable structure, which poses a considerable threat to the environment, construction processes and human life. In this study, double oedometer tests and scanning electron microscopy and mercury intrusion porosimetry analyses were conducted on loess from Yan’an to study the macroscopic and microscopic characteristics of loess wetting deformation and the underlying mechanism. The wetting collapse of loess under loading depends on the changes in different microstructure levels and elements. This collapse chain reaction is manifested by the dissipation, scattering and recombination of the cementation, deformation and reorganization of the particles, blocking of the pore channels, decrease in the dominant size and volume of unstable macropores (>14 µm) and abundant mesopores (2.5–14 µm), increase in the volume of small pores (0.05–2.5 µm), and volume contraction at the macroscale. This process is dependent on the initial water content, stress level and wetting degree. These findings can facilitate collapsible loess hazard prevention and geological engineering construction.

Freeze\u2013Thaw Resistance of Ternary Blended Concrete Using Ferronickel Slag

The present study investigated the resistance of concrete blended with ground granulated blast furnace slag (GGBS) and ferronickel slag (FNS) to cycles of freeze and thaw. The replacement ratio of the binders was 0%, 50 wt% of GGBS and 30 wt% of GGBS + 20 wt% of FNS for O100, OG50 and OG30F20, respectively. Specimens consisted of cement paste and concrete kept at 0.45 water/binder ratio. After 28 days of curing, specimens were subjected to freeze and thaw cycles (300) for measuring the variation of strength, weight loss and fundamental transverse frequency. Simultaneously mercury intrusion porosimetry was performed to examine the pore structure modifications at 28 days. The hydration products for cement paste cured at each determined age were characterized by X-ray diffraction and the content of CH and CSH was obtained from thermogravimetric analysis (TGA). As a result, the ternary blended concrete specimens showed lower deterioration degree when subjected to the freeze and thaw cycles. This may be due to a latent hydraulic and/or pozzolanic reaction producing more CSH in the matrix, which in turn increases the volume of small pores. The increased content of C–S–H gel for OG30F20 was confirmed by TGA, accounting for 69.9%. However, the binder system consisting of ordinary Portland cement and GGBS did not exhibit higher resistance to the given deleterious environment, presumably due to a delayed hydration process.

Microstructure analysis of crust during deep-fat or hot-air frying to understand French fry texture

This study aimed to identify the microstructural parameters of the crust which can explain the crispness of French fries. The French fry microstructure was visualized by X-ray micro-computed tomography (XMT). Analysis of the images provided information on the pore size distribution, global porosity of the French fries and local porosity of the crust region. The results revealed that prefrozen French fries do not practically undergo any volume shrinkage during frying. The total porosity created in French fries corresponds to the volume of water loss during frying. The difference between hot-air fried and deep-fat fried French fries was mainly related to the pore diameter and pore size distribution in the crust. Principal component analysis between the sensory and morphometric parameters showed that the volume of small pores (diameter < 0.15 mm) and the span of the pore size distribution in the first millimetres of the crust correlated with the crispness of the product (r > 0.85, P value < 0.05). Thus, a French fry is crispier if the pores generated in the crust have a small median diameter (diameter < 0.2 mm), as well as a large dispersion of pore diameters. • The French fry crust microstructure revealed by XMT is linked to crispness defined by sensory analysis. • The total porosity created in pre-frozen French fries corresponds to water loss. • A higher porosity in the crust generally results in a higher perceived crispness. • A small pore diameter and heterogeneous pore size distribution in the crust improve the crispness.

Fe-Cr pillared clay as catalysts for the ethanol to gasoline conversion

Bentonite is a clay mineral type of montmorillonite that can be used as a catalyst. The use of bentonite as a catalyst has weaknesses, namely small surface area, pore volume and low thermal stability, so it is necessary to modify the structure. Modification of bentonite structure carried out in this research used the pillarization method (Pillared Clay or PILC) with the addition of Fe and Cr metals to form Cr/PILC, Fe/PILC, and Fe-Cr/PILC catalysts. The PILC catalysts can be used as a catalyst in the ethanol to gasoline conversion processess for alternative fuels. The XRD result shows that the pillarization process with the addition of Fe and Cr metals was succeeded so it can increase the interlayer spacing by 22,03 Å, 15,79 Å, and 15,85 Å on the Cr/PILC, Fe/PILC, and Fe-Cr/PILC catalysts. The SAA result shows an increase in surface area and pore volume in the Cr/PILC, Fe/PILC, and Fe-Cr/PILC catalysts structure. The presence of Brønsted acid type is indicated through the absorption peaks at 1515-1640 cm−1 and Lewis acid type at 1435-1470 cm−1 from the FTIR result. The TGA result shows an increase in thermal stability on the Cr/PILC, Fe/PILC, and Fe-Cr/PILC catalysts. The Fe-Cr/PILC catalyst shows the best activity results on the ethanol to gasoline conversion process with the acquisition of percent conversion and selectivity by 43.30% and 87.15% respectively.

Cascade electron transfer in ternary CuO/α-Fe2O3/γ-Al2O3 nanocomposite as an effective visible photocatalyst

Highly efficient ternary heterojunction of CuO/α-Fe2O3/γ-Al2O3 was effectively fabricated by a facile and cost effective chemical route. The structural, chemical composition, morphology, optical and photocatalytic properties of as-prepared CuO/α-Fe2O3/γ-Al2O3 photo catalyst were compared to pristine and binary samples by various characterization. Existence of all the dominant peaks of CuO, α-Fe2O3 and γ-Al2O3 are noticeable in XRD spectrum of CuO/α-Fe2O3/γ-Al2O3 ternary photo catalyst which confirms the successful formation of the photocatalyst. SEM and HRTEM results revealed the spherical shape CuO nanoparticles with distorted α-Fe2O3 agglomerated plates which led to complete diffusion with γ-Al2O3. The band gap of ternary nanocomposite was found to be 1.9 eV elucidated by UV-DRS. Brunauer-Emmett-Teller (BET) analysis showed that as-fabricated ternary CuO/α-Fe2O3/γ-Al2O3 nanocomposite exhibited the porous structure with large surface area and small pore volume as compared to pristine γ-Al2O3.due to the unique ternary nanocomposite structure and synergistic effect among various components. The photocatalytic activity was examined by monitoring the deterioration of methyl orange under simulated solar light irradiation. CuO/α-Fe2O3/γ-Al2O3 exhibited superior photocatalytic efficacy as compared to CuO/γ-Al2O3 and α-Fe2O3/γ-Al2O3 binary and pure oxides of γ-Al2O3, CuO and α-Fe2O3. The marvelous photocatalytic activity of CuO/α-Fe2O3/γ-Al2O3 ternary nanocomposite samples can be ascribed to their close contact, strong interfacial hybridization and proficient charge transfer capacity. The electrochemical studies such as linear sweep voltammetry (LSV) and cyclic voltammetry (CV) were carried out to explore the charge transfer behavior and support the high photo activity of ternary nanocomposite CuO/α-Fe2O3/γ-Al2O3. LSV measurements manifested that CuO/α-Fe2O3/γ-Al2O3 exhibited 4.3 folds higher current density than bare γ-Al2O3 which confirmed the faster electron transfer from CuO to γ-Al2O3 via mediated α-Fe2O3 through the interfacial potential gradient in conduction band. Cyclic voltammetry (CV) results showed that pair of anodic and cathodic peaks in CuO/α-Fe2O3/γ-Al2O3 appeared which affirm the efficient increase in photo-induced e−/h+ separation and suppress recombination rate of electron-hole pair. This work demonstrated that CuO/α-Fe2O3/γ-Al2O3 ternary nanocomposite is found to be a promising candidate as an efficient adsorbent for organic dye removal from waste water.

A new model for gas adsorption isotherm at high pressures

This contribution discusses the derivation of a new model for gas adsorption isotherm at high pressures, from the Redlich-Kwong’s equation of state, instead of the virial equation used by the frequently employed Zhou model, where the involved virial coefficients have not direct physical information. The two models are based on the hypothesis that the adsorbate molecules behave like a real gas. Unlike Zhou model, in the proposed new model, the adsorption space (Vad) appears as a fitting parameter. To validate the proposed model, the values obtained for Vad from hydrogen adsorption isotherms recorded at 75 K and up to 10 bar, in a series of porous solids of the well-known crystalline structure were compared with the calculated accessible free volume in those solids. The difference between the calculated values of Vad and the expected ones, from structural considerations, varies from 3.3 to 16.3% depending of the material nature. The effects of the model's parameters on the isotherm shape are discussed in detail. The proposed adsorption model herein discussed has potential applications for the evaluation of adsorption data for gases above their critical temperature, among them hydrogen, and also to use the hydrogen adsorption as a probe molecule to sense the pore volume in porous solid of small pore volume and narrow windows, which could be inaccessible for other probe molecules.

Investigation of permeability decline due to coupled precipitation/dissolution mechanism in carbonate rocks during low salinity co-water injection

Low salinity water injection is a promising water-based enhanced oil recovery (EOR) method for carbonate rocks. However, permeability impairment resulted from competition between mineral scale precipitation and rock dissolution is not well understood due to complex injection water/formation brine/rock interactions. In this paper, simultaneous effects of rock dissolution and mineral scale precipitation in low saline co-water injection on permeability performance were investigated. A dynamic flow of water with varying ion composition considering scale precipitation/rock dissolution coupling with geochemical reactions (using PHREEQC) was developed. The proposed model was validated with outlet ion concentration of single phase coreflood data. Then, permeability decline curves were obtained for each mixing ratio of formation brine and diluted sea water. The results show that in case of co-water injection, mineral scale precipitation is the dominant mechanism in early times of flooding and can be comparable with rock dissolution quantitatively in longer time. This result is in contrast with results of sequensive injection available in literature due to lack of sufficient mixing zone between injected water and formation brine and small pore volume of injection. In addition there are three different regions in permeability curve of co-water injection which is reflecting the competition between mineral scale precipitation and rock dissolution mechanisms. Moreover, as the share of formation brine increased more than 0.5, mineral precipitation became dominant and permeability curve decreased monotonically. The model can be used for distinguishing share of different mechanisms of permeability variation during low salinity waterflooding.

Development of limestone calcined clay cement concrete in South China and its bond behavior with steel reinforcement

Limestone calcined clay cement (LC3), consisting of ordinary Portland cement (OPC) clinker, calcined clay, limestone powder, and gypsum, has been considered a promising solution to current challenges in the cement and concrete industry, such as high carbon emissions, high energy consumption, and resource shortages. This study carries out a series of experimental investigations of LC3-based paste, mortar, and concrete, including microstructural analyses (e.g. hydration product characterization and pore structure analysis) and macro-scale testing (e.g. workability and mechanical properties), using raw materials from south China. The results show that, in LC3 paste, the replacement of clinker by calcined clay and limestone leads to an increased volume of small pores but decreased total volume of pores. The workability of LC3 mortar and concrete can be readily tailored using conventional superplasticizers. When designed for comparable 28-d compressive strength, the LC3 mortar and concrete tend to have lower early-age compressive strength, but comparable compressive strength and higher flexural strength than those of the OPC counterparts at late ages. This study also examines the bond-slip behavior between LC3 concrete and steel bars and finds that the bond strength is comparable to that of OPC concrete with the same 28-d compressive strength, but that the LC3 concrete-rebar interface exhibits higher bond-slip stiffness. These findings on LC3 concrete provide fundamental information and guidance for furthering the application of LC3 binder in structural concrete in the near future.

Beneficial roles of carbon black additives in slurry phase hydrocracking of vacuum residue

Effects of carbon black (CB) additives with dispersed MoS2 catalysts (d-MoS2) on the slurry phase hydrocracking (HCK) of vacuum residue (VR) were studied in an autoclave batch reactor at 693 K and 9.5 MPa H2. For comparison, commercial NiMo catalysts supported on large and small pore volume Al2O3 (-LP, -SP) were also applied for the VR HCK. The structure of the catalysts was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS). The dispersed MoS2 (d-MoS2) was observed to form nanosized single slabs of 8.4 nm, while in the presence of CB the particle size of the d-MoS2-CB became even smaller (4.8 nm). A series of recycle runs of the VR HCK revealed high activity and stability of d-MoS2-CB followed by d-MoS2 > NiMo-LP > NiMo-SP. The kinetic analysis also demonstrated that the d-MoS2-CB shows a high asphaltene conversion with minimizing coke formation.

A breathable, sensitive and wearable piezoresistive sensor based on hierarchical micro-porous PU@CNT films for long-term health monitoring

Creating highly sensitive and comfortable flexible sensors remain a key challenge in the development of electronic-skin. A breathable, sensitive and long-term wearable piezoresistive sensor based on hierarchical micro-porous PU@CNT films and a single-sided electrode were prepared by simple and effective methods. Distilled water is used as a non-solvent to induce the separation of films polyurethane (PU) to create the hierarchical porous structures. The micro-computed tomography is used to quantitatively analyze the 3D structure of the porous films with different PU concentration, which is, a small pore volume of less than 50 μm3 occupy the majority, the porosities are from 64.25% to 40.27%, and the surface areas are of 5.6 × 106 to 12.0 × 106μm2. Such micro-porous structures performs the air and moisture permeability of the PU@CNT films and the sensors which are more than 8 times that of non-porous film, and effectively improves the sensitivity of the sensors to 51.53 kPa−1. The hysteresis error of the porous PU@CNT sensor which possesses a higher specific surface area and lower porosity is optimized by 67.8% and it has high stability (>8000 cycles). Finally, the sensors were successfully to detecting article pulse waves, throat and finger movements, and spatially resolved pressure.

Production of hydrogen by catalytic methane decomposition using biochar and activated char produced from biosolids pyrolysis

Catalytic methane decomposition (CMD) was studied by employing biochar and activated char of biosolids’ origin under different reaction temperatures and methane concentrations. Higher reaction temperatures and lower inlet methane concentrations were found to be favourable for achieving higher methane conversion. A maximum initial methane conversion of 71.0 ± 2.5 and 65.2 ± 2.3% was observed for activated char and biochar, respectively at 900 °C and for 10% CH4 in N2 within the first 0.5 h of experiment. Active sites from oxygen containing carboxylic acid functional groups and smaller pore volume and pore diameter were attributed to assist in higher initial methane conversion for biochar and activated char respectively. However, rapid blockages of active sites and surfaces of biochar and activated char due to carbon formation have caused a rapid decline in methane conversion values in the first 0.5 h. Later on, crystalline nature of the newly formed carbon deposits due to their higher catalytic activity have stabilised methane conversion values for an extended experimental period of 6 h for both biochar and activated char. The final conversion values at the end of 6 h experiment with biochar and activated char at 900 °C and for 10% CH4 in N2, were found to be 40 ± 1.9 and 35 ± 1.6% respectively. Analysing carbon deposits in detail revealed that carbon nanofiber type structures were observed at 700 °C while nanospheres of carbon were found at 900 °C.

Thermally and optically functionalized Anatase nano-cavities based fiber optic pH sensor

Owing to the fiber optic sensing applications, the cavity shaped cresol red (CR) immobilized anatase nanoparticles (CR-ANPs) are synthesized by sol-gel route. The homogeneous distribution of CR species within ANPs is confirmed by EDX mapping analysis. The chemical bonding between Ti and functional groups indicated the successful immobilization of CR species in the anatase matrix. Thermally stable CR-ANPs have average surface roughness ∼ 9 nm, a large surface area of 210 m2/g, small pore volume 0.12 cm3/g, and crystallite size 4 nm. The sensing response of the proposed device is found to be 7.05 counts/pH within pH 1-7 at 453 nm with the determination coefficient (R2) ∼ 0.95. Whereas, in basic media (pH 9-12), the sensor response is found to be 5.95 counts/pH. Experimental findings suggested that this proposed material is of pronounced interest because it can be used within extreme acidic and basic media without any deterioration/leaching.