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The promising potential of photodynamic therapy (PDT) has fueled the development of minimally invasive therapeutic approaches for cancer therapy. However, overcoming limitations in PDT efficacy in the hypoxic tumor environment and light penetration depth remains a challenge. We report the engineering of tungsten carbide nanoparticles (W2C NPs) for 1,064 nm laser-activated dual-type PDT and combined theranostics. The synthesized W2C NPs allow the robust generation of dual-type reactive oxygen species, including hydroxyl radicals (type I) and singlet oxygen (type II), using only single 1,064 nm laser activation, enabling effective PDT even in the hypoxic tumor environment. The W2C NPs also possess high photothermal performance under 1,064 nm laser irradiation, thus enabling synergistically enhanced cancer therapeutic efficacy of PDT and photothermal therapy. Additionally, the photoacoustic and X-ray computed tomography bioimaging properties of W2C NPs facilitate the integration of tumor diagnosis and therapy. The developed W2C based theranostic nanoagents increase the generation of reactive oxygen species in hypoxic tumors, improve the light penetration depth, and facilitate combined photothermal therapy and photoacoustic/computed tomography dual-mode bioimaging. These attributes could spur the exploration of transition metal carbides for advanced biomedical applications.

Numerical simulation has been widely used in nuclear reactor safety analyses to gain insight into key phenomena. This paper compares simulations of a single-phase steady flow in a 2 × 2 rod bundle with spacer grids among different codes based on the high pressure heat transfer facility at University of Wisconsin. The detailed computational fluid dynamics modeling methodology was developed using FLUENT to help in the facility design and pretest analyses. After comparison between different turbulence models, the Standard k-ω was chosen to simulate the effect of unheated solid walls and grid spacers. It was found that solid walls had a small influence on the flow and heat transfer behavior. We note the effect of rod-to-wall gap needs be taken into account if it is larger than half of the gap between the rods. We compared the simulations of FLUENT, COBRA-TF, and TRACE to determine the position of thermocouples to be used in the planned experiments. An investigation was performed on the effect of bendi...

We report a facile method by which to synthesize Au/Cdot nanohybrids using carbon dots (Cdots) obtained from rice straw as a direct reducing agent as well as a stabilizer. Rice-straw-derived Cdots possess oxygen-containing functional groups that act as an electron-donating source to reduce Au3+ to Au0 without the use of chemical reagents for the reduction of Au precursors. Additionally, the strong Au-carbon interaction promotes a high electron transfer of the Au/Cdot nanohybrid electrocatalyst, resulting in enhanced performance of the hydrogen evolution reaction (HER). The overpotential is 150 mV at a current density of 10 mA·cm−2 and the TOF value is 0.06·s−1, representing the most outstanding HER performance among Au-based catalysts as a non-Pt HER electrocatalyst. The HER activity is stably maintained for 2000 cycles as well as for 48 h. The synthesis of Cdots, the hybridization of Au/Cdot electrocatalyst, and the production of clean hydrogen fuel using Au/Cdots are zero CO2 emission strategies, not only preventing the emission of pollutants but also satisfying the energy needs of humankind.

This paper reports the synthesis of nanosized Ag/Co3O4 composite catalysts using a silver-mirror reaction and the calibration of their catalytic activities towards methyl blue (MB) dye degradation with peroxymonosulfate (PMS) under visible light. The nanosized Ag/Co3O4 composites were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–vis spectroscopy. The experimental evidence indicated that the hydrothermal synthesis approach lead to the exposure of the {1 1 2} facets of the Co3O4 nanoflakes. Compared to Co3O4 nanoflakes, Co3O4 doped with Ag nanoparticle (average diameters of 10–15 nm) presented lower band gap energy and photoluminescent (PL) intensity. Meanwhile, the Ag/Co3O4 exhibited high stability and excellent dispersion property in dye solution. Experimental data suggested that 3.06 wt% Ag nanoparticle-doped Ag/Co3O4 nanocomposite catalyst possessed the highest catalytic activity towards MB degradation in aqueous solution at the tested concentration level of 15 mg/L, about 2.4 times higher than that of pure Co3O4. Complete decolorization of the 15 mg/L MB solution can be achieved by 3.06 wt% Ag-doped Ag/Co3O4 nanocomposite within 20 min of visible light irradiation.

In this paper, we present a large area nanosecond pulse gas-liquid diffuse discharge plasma with small flow rate of helium as working gas. The discharge images, the waveforms of pulse voltage & current, the emission spectra, and the gas temperature are measured or calculated. As a energy-efficient sterilization for sewage, the efficiency of sewage sterilization in both static liquid and flowed liquid are investigated. It is found that an optimal value of helium gas flow rate in the production of reactive oxygen species (OH, O) can be obtained when the He flow rate is 5mlmin � 1 , under this condition, high inactivation efficiencies of bacteria and fungus can be presented.

In this study, we deposited nano-Co3O4 film on silicon substrate using plasma-enhanced metal—organic chemical vapor deposition (PEMOCVD), and the structure difference of Co3O4 crystallized by the annealing and the Ar/O2 plasma techniques were explored by SEM, TEM, XRD, and XPS. Compared to the net morphology of Co3O4 film treated with high calcinations temperature, the cauliflowers-shaped micro-clusters were changed to nano-catkin when the sample was treated with Ar and O2 plasma for 40 min. Additionally, both samples (annealed and plasma-treated) showed the formation of both the {311} and {220} planes. The surface richness of active Co3+ sites on the exposed {220} plane indicated that the as-deposited nano-Co3O4 films have potential catalytic properties for CO and hydrocarbon oxidation.

In this paper, a two-step process was explored for the modification of poly(ethylene terephthalate) (PET) fabrics by Ar/O 2 plasma-induced polymerization with hexamethylene diamine (HMD) monomer. The first step involved a parallel-plate shape dielectric barrier discharge (DBD) apparatus to modify the PET fabrics. This treatment could introduce some polar groups onto the PET surface, and also simultaneously increased the surface roughness. Thus, this process was very helpful to increase the linking intensity between the fabric substrate and the later polymerized layer. For the second step of the process, an atmospheric pressure plasma jet (APPJ) apparatus with Ar and O 2 as working gases was employed to achieve the polymerization with HMD monomer on the fabric surface. The measurement of the plasma gas temperature by infrared thermometry, and the detection of reactive species by optical emission spectroscopy were used for characterizing the polymerization process. It was found that the plasma gas temperature was not higher than 307 K when the applied power was lower than 50 W, and many reactive species (e.g. •OH, •H, •O) existed in the plasma. Field emission scanning electron microscopy images showed that the surface roughness of PET increased greatly with the DBD plasma treatment, and a smooth thin film was formed under the APPJ polymerization with HMD monomer. Fourier transform infrared spectroscopy results indicated that HMD polymer was incorporated into PET fabrics through the formation of new covalent bonds. Chemical composition was analyzed by X-ray photoelectron spectroscopy, and many functional groups (e.g. C–N, O = C–NH) occurred on the PET fabric surface. Meanwhile, the dyeing property of modified PET evaluated by color yield (K/S) analysis was improved obviously.

In this paper, the different discharge and polymerizing characteristics of Ar and He atmospheric pressure plasma jets (APPJs) were studied. The as-deposited polymer of acrylic acid (PAA) on silk fibroin film (SFF) by APPJs with Ar/O2 and He/O2 gases is investigated with AFM, FESEM and XPS. Optical emission spectroscopy (OES) measurements indicated that various reactive radicals, such as OH and O as well as some acrylic acid (AA) particles existed in the plasma jets. AFM images showed that the He/O2 plasma-deposited films had the most homogeneous characteristics and good water resistance properties. The cross-sections of silicon substrates obtained by FESEM showed that the deposition rates of PAA were 50 nm center dot min1 and 15nm center dot min1 for Ar/O2 and He/O2 plasmas, respectively. Also, according to XPS analysis, He/O2 plasma created a higher concentration of carboxyl groups on the deposited film than when Ar/O2 plasma was used.

The aim of this work is to coat silk fibers (SF) with polymer of acrylic acid (PAA) using an atmospheric pressure glow discharge (APGD) plasma jet in order to immobilize antimicrobial peptide LL-37. The polymer properties are characterized by contact angle goniometry (CAG), XPS, AFM and SEM. The CA of the SF film can be decreased to 340, and the surface roughness of PAA in the center of plasma jet is larger than in other areas. Compared with the original SF, the concentration of carboxyl group increases greatly when the SF are modified by Ar plasma jet polymerization of AA. The augmentation of functional groups is very useful to immobilize larger concentrations of microbial peptide LL-37 on the SF surface, and the satisfactory antimicrobial activity on inhibiting the Escherichia coli (E. coli) is thereby achieved.

The interactions between plasma-generated excited particles and water play an integral role in sustainable degradation of pharmaceutical compounds, improving aerobic respiration of activated sludge, and efficient removal of microorganisms from water, and are fundamental to the intentional transfer of reactivity from plasmas to biological solutions for such medical applications as cancer treatment and wound healing. The physical and chemical mechanisms that govern this transfer of reactivity are complex, and include concomitant generation and consumption of species in the gas and liquid phases, and at the interface. As such, it is challenging to predict the quantities of biologically-active radicals and molecules in liquid phase from gas phase measurements alone. Rapid and accurate quantification of reactive species, such as OH radicals and H2O2 molecules within the liquid phase and their link to specific biological effects is therefore critical for medical applications of plasma-activated solutions. Using a simple, low-cost method for trapping and stabilization of OH radicals by means of salicylic acid, this work seeks to provide further insights into the physics and chemistry of generation of OH radicals within the liquid phase, and integrate these findings with decontamination outcomes for four commonly used processing gases.

The biofilm of allylamine polymer was deposited by using the liquid sputtering apparatus, which was achieved by the atmospheric: cold plasma plume. The surface roughness of the polymer was improved by increasing the power and He gas velocity. The average allylamine polymer deposition rate was about 30 nm/min. Rich morphologies (e.g., nanoline, microcloudlet) appearing on the biofilm revealed the important information of the growing processes that occurred in the plasma deposition. The density of the amine groups was obviously related to the plasma parameters, and the highest density of amino-labeled DNA probe was about 0.9 pM/cm(2) confirmed by the dyed oligonucleotide. (C) 2008 Elsevier B.V. All rights reserved.

Using hexamethyldisiloxane (HMDSO) monomer, the magnetic nanoparticles (NPs) of nickel oxide (NiO) were modified by using an atmospheric room-temperature plasma fluidized bed (ARPFB). The plasma gas temperature of the ARPFB was not higher than 325 K, which was favorable for organic polymerization. The plasma optical emission spectrum (OES) of the gas mixture consisting of argon (Ar) and HMDSO was recorded by a UV–visible monochromator. The as-treated NPs were characterized by means of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results show that the assembling NPs were isolated greatly after modified by the organosilicon polymer. Moreover, this treatment process changed the wettability of the NPs from super-hydrophilicity to super-hydrophobicity, and the contact angle (CA) of water on the modified NPs surface exceeded 150°. Therefore, the ARPFB is a prospective technology for the NPs surface modification according to the different requirements.

(Ti,Ta)N films were prepared by pulsed high energy density plasma (PHEDP) from a coaxial gun in N2 gas. The coaxial gun is composed of a tantalum inner electrode and a titanium outer one. Material characteristics of the (Ti,Ta)N film were investigated by x-ray photoelectron spectroscopy and x-ray diffraction. The microstructure of the film was observed by a scanning electron microscope. The elemental composition and the interface of the film/substrate were analysed using Auger electron spectrometry. Our results suggest that the binary metal nitride film, (Ti,Ta)N, can be prepared by PHEDP. It also shows that dense nanocrystalline (Ti,Ta)N film can be achieved.

Plasma electrolytic oxidation (PEO), also called micro-arc oxidation (MAO) or anode spark deposition (ASD), is a novel technique to produce hard ceramic coatings on metals, such as aluminum, titanium, magnesium (called valve metals) and their alloys. Up to now, many researchers focused on the PEO process for workpieces of regular shapes such as cube, cake or stick samples, etc. But no one paid attention to the irregular samples such as tubular materials. This research emphasized the PEO process of long tubes, especially the way to obtain uniform thickness of ceramic coatings on inner surface of tubes. Furthermore, the PEO kinetic behaviors of aluminum tubes were also investigated. The potential difference between the electrodes indicated a linear relationship with the coating thickness. A central accessory electrode was axially used to eliminate the shielding effect of electric field and was effective to obtain axially uniform coating on the inner surface of the tubes. The combination of hot-dipping aluminum and PEO process to obtain ceramic coating on 45# steel tubes was also performed in this work.

The pulsed high energy density plasma (PHEDP) is generated in the working gas due to a high-voltage high-current discharge, within a coaxial gun. In PHEDP surface modification, discharge is applied for preparing the amorphous and nanostructured high-melting materials as thin films deposited on various substrates. In this investigation, Ta(C)N films were deposited using PHEDP on stainless steel. Pure tantalum and graphite were used as the inner and outer electrodes of the PHEDP coaxial gun, respectively. Nitrogen was used as the working gas and also one of the reactants. Preliminary study on the films prepared under different conditions shows that the formation of Ta(C)N is drastically voltage dependent. At lower gun voltage, no Ta(C)N was detected in the films; when the gun voltage reaches or exceeds 3.0 kV, Ta(C)N occurred. The films are composed of densely stacked nanocrystallines with diameter less than 30 nm, and some grains are within 10 nm in diameter.

Hard films prepared by pulsed high energy density plasma (PHEDP) are characterized by high film/substrate adhesive strength, and high wear resistance. Titanium carbonitride (TiCN) films were deposited onto YG11C (ISO G20) cemented carbide cutting tool substrates by PHEDP at room temperature. XRD, XPS, SEM, AES, etc. were adopted to analyze the phases (elements) composition, microstructure and the interface of the films, respectively. The results show that, the uniform dense films are composed of grains ranging from 70 to 90 nm. According to the AES result, there is a broad transition layer between the film and the substrate, due to the ion implantation effect of the PHEDP. The transition layer is favorable for the film/substrate adhesion.

A mechanical model of a laser transformation hardening specimen with a crack in the middle of the hardened layer is developed to quantify the effects of the residual stress and hardness gradient on crack driving force in terms of J-integral. It is assumed that the crack in the middle of the hardened layer is created after laser transformation hardening. Using a Double Cantilever Beam model, the analytic solutions, which can be used to quantify the effects of the residual stress and the hardness gradient resulting from laser transformation hardening on crack driving force, are obtained. A numerical example shows the crack driving force decrease is very sensitive to the residual compressive stress increase.

A novel atmospheric pressure plasma fluidized bed (APPFB) with one liquid electrode was designed, and its preliminary discharge characteristics were studied. The glow discharge in the APPFB was generated by applying a low power with helium (He) gas, and the plasma gas temperature was no higher than 320 K when the applied power was lower than 11 W. The plasma optical emission spectrum (OES) of the gas mixture consisting of He and hexamethyldisiloxane (HMDSO) was recorded by a UV-visible monochromator. The calcium carbonate powders were modified by APPFB using HMDSO in the He plasma. The powder surface energy was decreased greatly by coating an organosilicon polymer onto the powder surface. This surface modification process changed the wettability of the powder from super-hydrophilicity to super-hydrophobicity, and the contact angle of water on the modified powders surface was greater than 160°.

An atmospheric pressure glow discharge plume (APGD-p) using a dielectric barrier discharge reactor with one conductive liquid electrode was designed in our study. The preliminary characteristics of the plume and application in the degradation of a dye, methyl violet 5BN (MV-5BN), were presented in this paper. The APGD reactor produced a cold plasma plume with temperature not higher than 320 K at power 5 - 50 W. The MV- 5BN solution as a probe for dye wastewater was treated by the downstream gases of the plasma plume. The results indicated that the active argon (Ar) and nitrogen (N-2) gases had little effect on the MV- 5BN degradation, but the air and oxygen (O-2) gas depleted the organic molecules effectively. In particular, the downstream O-2 gas degraded the dye molecules entirely.

Plasma electrolytic oxidation (PEO) is a cost-effective technique that can be used to prepare ceramic coatings on metals such as Ti, Al, Mg, Nb, etc., and their alloys, but this promising technique cannot be used to modify the surface properties of steels, which are the most widely used materials in engineering. In order to prepare metallurgically bonded ceramic coatings on steels, a combined technique of arc spraying and plasma electrolytic oxidation (PEO) was adopted. In this work, metallurgically bonded ceramic coatings on steels were obtained using this method. We firstly prepared aluminum coatings on steels by arc spraying, and then obtained the metallurgically bonded ceramic coatings on aluminum coatings by PEO. The characteristics of duplex coatings were analyzed by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The corrosion and wear resistance of the ceramic coatings were also studied. The results show that, duplex Al2O3/aluminum coatings have been deposited on steel substrate after the combined treatment. The ceramic coatings are mainly composed of alpha-Al2O3, gamma-Al(2)o(3), theta-Al2O3 and some amorphous phase. The duplex coatings show favorable corrosion and wear resistance properties. The investigations indicate that the combination of arc spraying and plasma electrolytic oxidation proves a promising technique for surface modification of steels for protective purposes. (c) 2005 Elsevier B.V. All rights reserved.

The in-situ titanium nitride (TiN) coating with a great thickness was reactive plasma sprayed in a nitrogen-containing environment. The microhardness of the coating was measured, and the indentations were used to determine the fracture toughness of the coating. The toughening mechanism was characterized by analyzing the SEM morphologies of TiN coating's fracture surfaces. Results show that the coating possesses a high hardness and toughness. The average hardness of the coating is 1200H(V) (100) (g); and the fracture toughness (K-IC) of it is 4.51 MPa center dot m(0.5). The cross-section of the TiN coating shows an obvious phenomenon of indentation size effect (ISE). The toughening mechanisms of the coating are crack deflection and pores, etc. (c) 2004 Elsevier B.V. All rights reserved.

Surface rapid solidification microstructures of AISI 321 austenitic stainless steel and 2024 aluminum alloy have been investigated by electron beam remelting process and optical microscopy observation. It is indicated that the morphologies of the melted layer of both stainless steel and aluminum alloy change dramatically compared to the original materials. Also, the microstructures were greatly refined after the electron beam irradiation.

The effects of electron beam surface hardening treatment on the microstructure and hardness of AISI D3 tool steel have been investigated in this paper. The results showed that the microstructure of the hardened layer consisted of martensite, a dispersion

Electron beam surface remelting has been carried out on AISI D2 cold-worked die steel. The microstructure and hardening behavior of the electron beam surface remelted AISI D2 cold-worked die steel have been studied by means of optical microscopy and Vickers hardness testing. It was found that AISI D2 steel can be successfully surface hardened by electron beam surface remelting. This surface hardening effect can be attributed to microstructural refinement following electron beam surface remelting. (C) 2002 Elsevier Science B.V. All rights reserved.

In this paper, the collective effects of combining heterogeneous Ag/TiO2 nanocomposite catalyst with the byproducts (primarily the irradiation and the O3 species) of an atmospheric pressure plasma jet (APPJ) system on the degradation of methyl orange (MO) were explored. The heterostructured Ag/TiO2 nanocomposite was achieved via decorating the Ag quantum dots (QDs) on the commercially available TiO2 catalyst (P25) through a hydrothermal method. The x-ray diffraction analysis of the nanocomposite catalyst showed the diffraction peaks at 44.3°, 64.4°, and 77.5°, corresponding to the Ag planes of (200), (220) and (311), respectively. The high resolution transmission electron microscope characterization of the nanocomposite catalyst indicated that the Ag QDs with an average diameter of 5 nm were homogeneously distributed on the P25 surface. The experimental results on the MO photodegradation showed that the APPJ irradiation had a marginal effect on the cleavage of the MO molecules. When the Ag/TiO2 nanocomposite catalyst was used, the photodegradation rate of MO increased about 5 times. When both the APPJ byproducts and the Ag/TiO2 nanocomposite catalyst were used, however, over 90% of the MO in the tested solution was cleaved within 15 min, and the energy efficiency was about 0.6 g/kW h. Moreover, an optimal Ag dosage value was determined (6 wt%). The catalytic results indicated that combining the DBD plasma byproducts with heterogeneous nanocomposite catalysts may be an effect protocol for decreasing the application cost of the DBD system and mitigating the environment pollution by organic dyes in the textile industry.

Rapid solidification microstructures of SiCp/Al-Si composite and the monolithic alloy are comparatively studied through laser remelting process. In the case of composite, particles disturb the orderly arrangement of primary alpha-Al dendrites observed in the base alloy. The underlying mechanisms are rationalized based on the interaction between the particle and aluminium melt.

In this paper, a highly catalytic and nanosized Ag / Co 3 O 4 composite for rhodamine B ( RhB ) degradation was fabricated by using the co-precipitation method at room temperature. The Ag / Co 3 O 4 structure and catalytic properties were characterized through scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) gas-sorption measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-Vis spectroscopy. The results showed that the Co 3 O 4 nanosheets prepared by hydrothermal synthesis mainly exposed (2 2 0) and (1 1 1) facets, which played an important role in determining its catalytic oxidation performance. The Co 3 O 4 nanosheets doped with Ag nanoparticles by a simple silver-mirror reaction exhibited a stable and well-dispersed property in dye solution. Compared to the Ag and Co 3 O 4 nanostructure, the Ag nanoparticles with bigger diameter (10 nm) on Co 3 O 4 surface also readily produced surface-active oxygen species and exhibited a higher catalytic activity for the degradation of RhB solution (5 mg ⋅ L-1) under the visible light. The kinetic constant K of Ag / Co 3 O 4 catalyst for RhB degradation reaction was evaluated to 0.02724 min-1, which is relatively higher than those reported in the literatures.

In this paper, homogenous gold nanoparticles ( AuNPs ) with a high density and a narrow size distribution were successfully fabricated on titanate nanowires (TNWs) scaffolds in the absence of organic capping agents. An ameliorated low-temperature hydrothermal method was used to prepare the TNWs scaffolds like bird's nest on the Ti substrate, and the nanowires diameter was about 30–80nm. Then, AuNPs were synthesized on the TNWs scaffolds with a deposition–precipitation urea (DPU) method. The TEM and XRD measurements indicated that well-crystallized face-centered cubic (fcc) AuNPs were homogeneously dispersed on TNWs, and AuNPs with average sizes of 2.7 nm and 4 nm were obtained, respectively for the theoretical gold loading 5 wt.% and 8 wt.%. Inspiringly, the 8%- AuNPs /TNWs catalyst could reduce 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) within 210 s, and exhibited better catalytic reduction performance than that of 5%- AuNPs /TNWs.

Without adding any surfactant, CeO 2 nanoparticles and nanorods are prepared by a very simple hydrothermal method. CeO 2 nanocrystals with different morphologies were synthesised simply by dropping ammonia into cerium nitrate [Ce(NO 3 ) 3 ·6H 2 O] water solution at room temperature. The obtained samples were characterised by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy and UV-visible absorption spectroscopy. The results show that all samples are indexed to phase of CeO 2 . The synthesised nanoparticles are spherical with a 10-30-nm diameter and the nanorods are 100-200-nm in length and 5-10-nm in diameter. The morphology of CeO 2 transforms from granular to rod-like with the ammonia concentration increasing from 0.5, 1 to 2 mol/l. The UV vis spectra exhibit a slight red shift because of increasing crystallite size.