Characterisation of wear particles from biomedical carbon/carbon composites with different preforms in hip joint simulator

A hip joint simulator was employed to predict the clinical wear behaviour of carbon/carbon （C/C） composites with needled carbon cloth preform and carbon felt preform. Wear particles generated from the two kinds of C/C composites were isolated and characterised by the size distribution and morphology. The evolvement of wear particles in the hip joint simulator was proposed. The results show that the wear particles from two kinds of C/C composites have a size ranging from submicron to tens of micrometers. The wear particles have various morphologies including broken fiber, fragment fiber, slice pyrolytic carbon and spherical pyrolytic carbon. C/C composites with needled carbon cloth preforms have larger size range and more broken fiber particles and slice pyrolytic carbon particles in comparison with C/C composites with carbon felt preforms. The evolvement of pyrolytic carbon particles is caused by surface regularization, whereas, the evolvement of carbon fiber particles is related to stress direction in the hip joint simulator.

Black Carbon Particles in the Urban Atmosphere in Beijing

A study of the concentration of black carbon particles and its variation in the urban atmosphere has been carried out since 1996 in the Beijing area. The measurements were done in the late autumn and early winter each year, the period before and after domestic heating activities begin. The results show the presence of black carbon particles at the high level that vary over a large range in the urban atmosphere in Beijing. The mean value of daily average concentration for the whole observation period of 1996-2004 is 20.0 μgm^-3. An evident decrease of black carbon particle concentration in the Beijing area is observed after 2000, and the daily average concentration of black carbon particles is estimated to be 16.0 μgm^-3 with a variation range of 2.10-50.50 μgm^-3 for the period of 2000-2004. The observation method and main variation behavior characteristics of black carbon particles in the urban atmosphere in the Beijing area are given and discussed.

The Enhancement of CO2 Chemical Absorption by K2CO3 Aqueous Solution in the Presence of Activated Carbon Particles

The enhancement of chemical absorption of CO2 by K2CO3/H2O absorbents in the presence of activated carbon （AC） particles was investigated. The results show that the gas absorption rates can be enhanced significantly in the presence of AC particles, and the maximum enhancement factor 3.7 was observed at low stirring intensities. The enhancement factor increased rapidly with the solid loading during the initial period of absorption and then be- came mild gradually to a maximum value. Both the liquid-solid contact area and the probability of solid particles residing at the gas-liquid interface decreased with the increase of the particle size, leading to a negative effect on the enhancement of mass transfer. The influence of the particles on gas absorption decreased with the reaction rate. The stirring speed changed the interfacial coverage and mass transfer rate on the liquid side and consequently affected the mass transfer between the gas and liquid phases; the enhancement factor decreased with the stirring intensity. A heterogeneous two-zone model was proposed for predicting the enhancement factor and the calculated results agreed well with the experimental data.

Fabrication of cast carbon steel with ultrafine TiC particles

The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and the large sized components to be fabricated in short processing time. However, it is extremely difficult to obtain uniform dispersion of ultrafine ceramic particles in liquid metals due to the poor wettability and the specific gravity difference between the ceramic particle and metal matrix. In order to solve these problems, the mechanical milling (MM) and surface-active processes were introduced. As a result, Cu coated ultrafine TiC powders made by MM process using high energy ball milling machine were mixed with Sn powders as a surfactant to get better wettability by lowering the surface tension of carbon steel melt. The microstructural investigations by OM show that ultrafine TiC particles are distributed uniformly in carbon steel matrix. The grain sizes of the cast matrix with ultrafine TiC particles are much smaller than those without ultrafine TiC particles. This is probably due to the fact that TiC particles act as nucleation sites during solidification. The wear resistance of cast carbon steel composites added with MMed TiC/Cu-Sn powders is improved due to grain size refinement.

First-principles kinetics study of carbon monoxide promoted Ostwald ripening of Au particles on FeO/Pt(111)

The dynamic and kinetic evolution of supported metal particles in the presence of reactants is decisive in shaping the nature of the catalytic active sites and the deactivation process. Ostwald ripening of FeO/Pt(111) supported Au particles in the presence of carbon monoxide is addressed here by firstprinciples kinetics. It is found that CO stabilizes the ripening monomer(Au atom) by forming favorable Au carbonyls with lower total activation energy, and corresponding phase diagram at wide range of temperature and CO pressures is constructed. Evolution of particle number, dispersion and particle size distribution of supported Au particles are explored. Great influence of CO promotion on ripening kinetics is revealed and explored in details, and mbar range of CO can lower the onset temperature of ripening by a few hundred kelvins. The present work reveals the crucial role of the metal-reactant complexes formed under reaction conditions on ripening of metal catalysts.

In situ formation of multiple catalysts for enhancing the hydrogen storage of MgH_(2) by adding porous Ni_(3)ZnC_(0.7)/Ni loaded carbon nanotubes microspheres

MgH_(2) is considered one of the most promising hydrogen storage materials because of its safety,high efficiency,high hydrogen storage quantity and low cost characteristics.But some shortcomings are still existed:high operating temperature and poor hydrogen absorption dynamics,which limit its application.Porous Ni_(3)ZnC_(0.7)/Ni loaded carbon nanotubes microspheres(NZC/Ni@CNT)is prepared by facile filtration and calcination method.Then the different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%)is added to the MgH_(2) by ball milling.Among the three samples with different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%),the MgH_(2)-5 wt%NZC/Ni@CNT composite exhibits the best hydrogen storage performances.After testing,the MgH_(2)-5 wt%NZC/Ni@CNT begins to release hydrogen at around 110℃ and hydrogen absorption capacity reaches 2.34 wt%H_(2) at 80℃ within 60 min.Moreover,the composite can release about 5.36 wt%H_(2) at 300℃.In addition,hydrogen absorption and desorption activation energies of the MgH_(2)-5 wt%NZC/Ni@CNT composite are reduced to 37.28 and 84.22 KJ/mol H_(2),respectively.The in situ generated Mg_(2)NiH_(4)/Mg_(2)Ni can serve as a"hydrogen pump"that plays the main role in providing more activation sites and hydrogen diffusion channels which promotes H_(2) dissociation during hydrogen absorption process.In addition,the evenly dispersed Zn and MgZn2 in Mg and MgH_(2) could provide sites for Mg/MgH_(2) nucleation and hydrogen diffusion channel.This attempt clearly proved that the bimetallic carbide Ni_(3)ZnC_(0.7) is a effective additive for the hydrogen storage performances modification of MgH_(2),and the facile synthesis of the Ni_(3)ZnC_(0.7)/Ni@CNT can provide directions of better designing high performance carbide catalysts for improving MgH_(2).

Black Carbon Instead of Particle Mass Concentration as an Indicator for the Traffic Related Particles in the Brussels Capital Region

The Brussels Capital Region has difficulties in meeting the stringent EU daily limit value for PM10 in all its measuring sites. Postponing the attainment of the deadline was not granted by the EU Commission, mainly due to insufficient judged measures to reduce road traffic emissions. However, a thorough analysis of the data makes clear that neither the particle mass concentration (PM10 and PM2.5) nor the particle number concentration are specific metrics for evaluating the particle pollution originated by traffic. In fact, increased formation of secondary aerosol, together with adverse meteorological conditions and the (re) suspension of the coarser fraction are by far the three main explanations for the numerous PM10 exceeding values. From our experience, amongst the particles measured, only the results for Black Carbon (BC), mainly present in the lower submicron range, are reflective of the direct influence of local traffic. Measured at two traffic sites along with PM mass and number concentrations, the data for Black Carbon show a striking correlation with nitrogen monoxide, a parameter strongly related with the proximity of the local traffic. The correlation factor between Black Carbon data and NO or NOX is much higher than between Black Carbon and the PM mass or number concentration. Therefore the assessment of traffic related particles should consider Black Carbon rather than PM10 or PM2.5.

Carbon enhanced nucleophilicity of Na_(3)V_(2)(PO_(4))_(3):A general approach for dendrite-free zinc metal anodes

Zincophilic property and high electrical conductivity are both very important parameters to design novel Zn anode for aqueous Zn-ion batteries(AZIBs).However,single material is difficult to exhibit zincophilic property and high electrical conductivity at the same time.Herein,originating from theoretical calculation,a zincophilic particle regulation strategy is proposed to address these limitations and carbon coated Na_(3)V_(2)(PO_(4))_(3)is taken as an example to be a protective layer on zinc metal(NVPC@Zn).Na_(3)V_(2)(PO_(4))_(3)(NVP)is a common cathode material for Zn-ion batteries,which is zincophilic.Carbon materials not only offer an electron pathway to help Zn deposition onto NVPC surface,but also enhance the zinc nucleophilicity of Na_(3)V_(2)(PO_(4))_(3).Hence,this hybrid coating layer can tune zinc deposition and resist side reactions such as hydrogen generation and Zn metal corrosion.Experimentally,a symmetrical battery with NVPC@Zn electrode displays highly reversible plating/stripping behavior with a long cycle lifespan over 1800 h at2 mA cm^(-2),much better than carbon and Na_(3)V_(2)(PO_(4))_(3)solely modified Zn electrodes.When the Na_(3)V_(2)(PO_(4))_(3)is replaced with zincophobic Al2O3or zincophilic V2O3,the stability of the modified zinc anodes is also prolonged.This strategy expands the option of zincophilic materials and provides a general and effective way to stabilize the Zn electrode.

Photocatalysed Reduction of Aqueous Sodium Carbonate Using LaCoO_3 Nano Particles

Heterogeneous photocatalysed reduction of aqueous Na_2CO_3 was carried out by using nano LaCoO_3 semiconductor powders. Formic acid and formaldehyde were identified as photoproducts,and were measured spectrophotometrically using Nash reagent. The effect of different parameters such as sodium carbonate concentration,amount of photocatalyst and different light sources on the yield of photoproducts was also investigated. It shows that nano LaCoO_3 has photocatalytic activity. Irradiation leads to the production of electrons in the conduction band of the LaCoO_3 semiconductor. It is likely that the photoproduced electrons initially reduce CO_3 (2-) to HCOO -,and then to HCHO and CH_3OH.

Experimental investigation of oil particles filtration on carbon nanotubes composite filter

Due to the lipophilicity of carbon nanotubes (CNTs),the carbon nanotubes composite filter for removing oil particles in cooking fumes is synthesized. The composite filter was fabricated by the chemical vapor deposition (CVD) method. The filtration characteristics of the resultant filter and the influence of the parameters were investigated. The results show that the filtration efficiency of the CNT filter during the saturation period is 99.92%, which satisfies the high efficiency particulate air (HEPA) standard. Pressure drop increases linearly before saturation and the pressure drop at the saturation stage is only two times that of the initial stage, which is far less than that of conventional glass fiber filters. The efficiency increases by enhancing filtration velocity. Pressure drops in the composite filter at the equilibrium stage are equal under different aerosol concentrations. The increase in concentration can improve the efficiency of composite filters. Therefore, the CNT filter is suitable for decreasing oil particle pollution due to its lower increase ratio of pressure drop and higher efficiency.

Environmental influence on transparent exopolymer particles and the associated carbon distribution across northern South China Sea

Microgels are plankton-derived transparent exopolymer particles(TEP)and have a significant impact on global marine carbon cycle.We investigated the influence of biogeochemical variables on the pattern of TEP abundance and its associated carbon(TEP C)distribution through a vertical transect of the northern South China Sea(nSCS)during summer,2014.The average TEP concentration was 58.32±30.56μg Xeq./L.Vertically,it was higher in the subsurface water column and lower at 200-m water depths.As chlorophyll a(chl a),TEP,and TEP C were highly concentrated at the bottom of the study transect,mainly on the continental shelf bottom and slope regions.Among biotic factors,cyanobacteria,especially Trichodesmium thiebautii showed significant positive correspondences with TEP through studied water columns in nSCS.In addition,TEP showed a positive correlation with chl-a distribution and clustered closely with diatom as well.It indicates a combined contribution of them on TEP sourcing accordingly.Nutrient concentrations were also high due to estuarine diluted water from Zhujiang(Pearl)River in the season that may intrigue those scenarios.Significant positive correlation(P<0.05)among biotic and abiotic parameters also supported the statement.Furthermore,mentionable contribution of TEP-derived TEP C was found after comparing the particulate organic carbon data,which may signify the importance of TEP in local carbon cycle in the nSCS.

Infiltration of Black Carbon Particles from Residential Woodsmoke into Nearby Homes

In many communities, residential wood burning is the source of a significant fraction of wintertime PM2.5 and produces exposures to nearby residents inside their homes. To evaluate the magnitude of this effect, black carbon particles were measured as a proxy for woodsmoke indoors and outdoors in a community where residential woodsmoke is the only significant particle source. Thirteen indoor/outdoor measurement pairs were obtained at 4 different residences and showed an average indoor/outdoor concentration ratio of 0.78 ± 0.21 for residences without indoor generation. In addition, a time dependent mass balance model was used in conjunction with aethalometer measurements taken over 16 nights at a single residence to estimate an average air exchange rate of 0.26 ± 0.08 h-1, an average deposition loss rate of 0.08 ± 0.03 h-1, and an average penetration factor of 0.97 ± 0.02. Using a mechanistic approach which utilizes these average values in a steady state model, the predicted average infiltration factor was 0.74 for the residence studied. The high values for both measured I/O ratio and modeled infiltration factor show that residential environments provide inhabitants with relatively little protection from recently generated wood smoke particles.

Superfast and solvent-free core-shell assembly of sulfur/carbon active particles by hail-inspired nanostorm technology for high-energy-density Li-S batteries

The demand on low-carbon emission fabrication technologies for energy storage materials is increasing dramatically with the global interest on carbon neutrality.As a promising active material for metal-sulfur batteries,sulfur is of great interest due to its high-energy-density and abundance.However,there is a lack of industry-friendly and low-carbon fabrication strategies for high-performance sulfur-based active particles,which,however,is in critical need by their practical success.Herein,based on a hail-inspired sulfur nano-storm(HSN)technology developed in our lab,we report an energy-saving,solvent-free strategy for producing core-shell sulfur/carbon electrode particles(CNT@AC-S)in minutes.The fabrication of the CNT@AC-S electrode particles only involves low-cost sulfur blocks,commercial carbon nanotubes(CNT)and activated carbon(AC)micro-particles with high specific surface area.Based on the above core-shell CNT@AC-S particles,sulfur cathode with a high sulfur-loading of 9.2 mg cm^(-2) delivers a stable area capacity of 6.6 mAh cm^(-2) over 100 cycles.Furthermore,even for sulfur cathode with a super-high sulfur content(72 wt%over the whole electrode),it still delivers a high area capacity of 9 mAh cm^(-2) over50 cycles in a quasi-lean electrolyte condition.In a nutshell,this study brings a green and industryfriendly fabrication strategy for cost-effective production of rationally designed S-rich electrode particles.

Comments on“Adsorption behavior of heavy metal ions by carbon nanotubes grown on microsized Al_2O_3 particles”

Recently, Hsieh and Horng [1] published the paper entitled as above. In section 3 results and discussion, the authors mentioned the first and the second order kinetic models without any quotations. In fact these two kinetic models have been published [2-5]. In order to distinguish a kinetics model based on the ad- sorption capacity of a solid from the one based on the concentration of a solution, Lagergren＇s first-order rate equation has been called pseudo-first-order [6-7]. The Lagergren＇s equation has been widely cited, but there are far more mistakes made in the quotation and in the reference section of papers, including the title, the author＇s name, journal title, year of publishing, volume, and page number [3]. In addition, the second order kinetic expression for the adsorption systems of divalent metal ions using sphagnum moss peat has been reported by Ho [8].

Magnetic properties of multi-walled carbon nanotubes encapsulated Fe/Co particles

The experimental apparatus by self-designed was used,Fe/Co particles encapsulated in multi-walled carbon nanotubes(MWCNTs) were prepared by the method of anodic arc discharging plasma. The products were characterized by transmission election microscopy,Raman spectroscopy and X-ray diffractometry. The magnetic properties of the products were characterized with vibration sample magnetometer. The TEM results show that MWCNTs have little impurity and good particles size,and Fe/Co with high continuity encapsulaties in carbon nanotubes. The saturated magnetization(σs),remanence(σm) and coercivity(Hc) of the sample are 17.30 A/(m·kg),3.96 A/(m·kg) and 31 521.60 A/m,showing better ferromagnetism compared with the bulk Fe/Co. The optimal conditions in this case are as follows:a helium gas atmosphere of 6.0×104 Pa,an arc current of 70 A,a voltage drop of 24 V,a constant distance of about 2 mm between the anodes and cathode,metallic powder contents of Fe and Co of 15.0%(mass fraction) and 15.0%,respectively,and well cooled electrodes and collector. This process is a convenient and effective that Fe/Co particles can be encapsulated in MWCNTs.

Daytime-nighttime variations in the concentration of PM_(0.1) carbonaceous particles during a biomass fire episode in Chiang Mai,Thailand

Carbonaceous aerosols affect air quality adversely,affect global warming,and human health.However,our understanding of the impact of ultrafine(PM_(0.1))carbonaceous particulate matter is incomplete,particularly the effects during haze episodes.This study monitored diurnal variations in PM_(0.1) in Chiang Mai,Thailand,from March to April 2020.We investigated carbonaceous PM_(0.1) collected by an ambient nano-sampler and evaluated their effect by using a carbon analyzer(IMPROVE_TOR).The results showed that burning large open areas in the dry season was crucial for increasing the particle mass concentration because of the large open burnings that occurred in this area.The majority of biomass fires near the sampling site occurred during the night,which would allow more particles to be released thus resulting in higher concentrations of PM_(0.1).Hence,the release of PM_(0.1) during the night would obviously result in higher concentrations than that during the day.In the eight carbon profiles,organic carbon 3(OC3)was predicted to be a marker of biomass fires.The carbon indices displayed that PM_(0.1) was influenced by biomass burning both daytime and nighttime.The findings reported herein should be of great impor-tance in terms of establishing biomass burning control policies for mitigating heavy haze pollution in Thailand and elsewhere.

Size-fractionated carbonaceous particles and climate effects in the eastern region of Myanmar

This study reports on an investigation of fine and coarse carbonaceous particulate matters(PM)in Tachileik,eastern Myanmar,during the dry and wet seasons of 2022.The carbon compositions,including organic carbon(OC)and elemental carbon(EC),in each size(PM10-2.5,PM2.5-1.0,and PM1.0-0.5)were determined by a carbon analyzer.The average total mass concentration of the three fractions of particle samples during the dry season was higher(51.23±23.86μg/m3)than that of the wet season(14.00±5.26μg/m3).The results indicate that OC and EC levels were highest for PM1.0-0.5 during the dry season and the sizes were similar for both seasons.The OC/EC ratios varied in different seasons,from 1.93 to 4.40 and 4.13 to 5.25 in the dry and wet seasons,respectively.EC was sub-divided into char-EC and soot-EC;the char-EC/soot-EC in the dry season was higher than in the wet season,signifying that biomass burning is the main particle source during the dry season.However,vehicle emissions dominated during the wet season.The effective carbon ratio(ECR)suggested that finer particles contributed more to global warming.This information is important in terms of air quality control and mitigation in Myanmar and elsewhere.

Seasonal Variations of Number Size Distributions and Mass Concentrations of Atmospheric Particles in Beijing

Particle number and mass concentrations were measured in Beijing during the winter and summer periods in 2003, together with some other parameters including black carbon (BC) and meteorological conditions. Particle mass concentrations exhibited low seasonality, and the ratio of PM2.5/PM10 in winter was higher than that in summer. Particle number size distribution (PSD) was characterized by four modes and exhibited low seasonality. BC was well correlated with the number and mass concentrations of accumulation and coarse particles, indicating these size particles are related to anthropogenic activities. Particle mass and number concentrations (except ultra-fine and nucleation particles) followed well the trends of BC concentration for the majority of the day, indicating that most particles were associated with primary emissions. The diurnal number distributions of accumulation and coarse mode particles were characterized by two peaks.

Particle size distribution and property of bacteria attached to carbon fines in drinking water treatment

The quantitative change and size distribution of particles in the effluents from a sand filter and a granular activated carbon （GAC） filter in a drinking water treatment plant were investigated. The average total concentration of particles in the sand filter effluent during a filter cycle was 148 particles/mL, 27 of which were larger than 2 μm in size. The concentration in the GAC effluent （561 particles/mL） was significantly greater than that in the sand filter effluent. The concentration of particles larger than 2 μm in the GAC filter effluent reached 201 particles/mL, with the amount of particles with sizes between 2 μm and 15 μm increasing. The most probable number （MPN） of carbon fines reached 43 unit/L after six hours and fines between 0.45 μm and 8.0 μm accounted for more than 50%. The total concentration of outflowing bacteria in the GAC filter effluent, 350 CFU （colony-forming units） /mL, was greater than that in the sand filter effluent, 210 CFU/mL. The desorbed bacteria concentration reached an average of 310 CFU/mg fines. The disinfection efficiency of desorbed bacteria was lower than 40% with 1.5 mg/L of chlorine. The disinfection effect showed that the inactivation rate with 2.0 mg/L of chloramine （90%） was higher than that with chlorine （70%）. Experimental results indicated that the high particle concentration in raw water and sedimentation effluent led to high levels of outflowing particles in the sand filter effluent. The activated carbon fines in the effluent accounted for a small proportion of the total particle amount, but the existing bacteria attached to carbon fines may influence the drinking water safety. The disinfection efficiency of desorbed bacteria was lower than that of free bacteria with chlorine, and the disinfection effect on bacteria attached to carbon fines with chloramine was better than that with only chlorine.

Iron Species-Impregnated Granular Activated Carbon as Modified Particle Electrodes Applied in Benzothiazole Adsorption and Electrocatalytic Degradation

The object of this study is to prepare iron species-impregnated granular activated carbon as particle electrodes in order to improve their adsorption and electrocatalytic degradation capacity in Benzothiazole removal.The incorporation of Fe-containing catalysts was performed by Fe(NO_3)_3 impregnation.The obtained samples were characterized by BET,Fourier transform infrared spectroscopy,SEM-EDS,powder X-ray diffraction,X-ray photoelectron spectra and TG.Compared with pure activated carbon,this modified particle electrodes show higher static adsorption capacities and TOC removal,which have respectively increased by25.9% and 54.4%.Both physisorption and chemisorption exist in the process of benzothiazole adsorption,where the latter plays a major role.In this way,the Fe-containing catalysts on modified particle electrodes are demonstrated to make a greater contribution to the improvement of electrocatalytic degradation by decreasing the activated energy by 32%.