X-ray Contact Research Articles

A novel rectal applicator for contact radiotherapy with HDR 192Ir sources

PurposeDose escalation to rectal tumors leads to higher complete response rates and may thereby enable omission of surgery. Important advantages of endoluminal boosting techniques include the possibility to apply a more selective/localized boost than using external beam radiotherapy. A novel brachytherapy (BT) rectal applicator with lateral shielding was designed to be used with a rectoscope for eye-guided positioning to deliver a dose distribution similar to the one of contact x-ray radiotherapy devices, using commonly available high-dose-rate 192Ir BT sources. Methods and MaterialsA cylindrical multichannel BT applicator with lateral shielding was designed by Monte Carlo modeling, validated experimentally with film dosimetry and compared with results found in the literature for the Papillon 50 (P50) contact x-ray radiotherapy device regarding rectoscope dimensions, radiation beam shape, dose fall-off, and treatment time. ResultsThe multichannel applicator designed is able to deliver 30 Gy under 13 min with a 20350 U (5 Ci) source. The use of multiple channels and lateral shielding provide a uniform circular treatment surface with 22 mm in diameter. The resulting dose fall-off is slightly steeper (maximum difference of 5%) than the one generated by the P50 device with the 22 mm applicator. ConclusionsA novel multichannel rectal applicator for contact radiotherapy with high-dose-rate 192Ir sources that can be integrated with commercially available treatment planning systems was designed to produce a dose distribution similar to the one obtained by the P50 device.

Uniform surface modification of polyethylene terephthalate (PET) by atmospheric pressure plasma jet with a horn-like nozzle

This work reports on surface modification of polyethylene terephthalate (PET) polymer by an atmospheric pressure plasma jet (APPJ) operated with argon. A distinguishable feature of this device is that it terminates with a conical horn-like nozzle. Three different nozzles diameters were employed with the purpose to obtain uniform surface modification over large area. Treatments in small 3D objects that fit inside the conical horn were also conducted. In this study, water contact angle (WCA) measurements and X-ray photoelectron spectroscopy (XPS) were performed to assess the samples wettability and the surface elemental composition, as well as, their radial distribution. Plasma-induced changes on the polymer surface morphology were evaluated by Atomic Force Microscopy (AFM). Electrical characterization of the plasma and investigation of the effect of the gas flow rate on the discharge power were carried out. After the plasma treatment PET surface became more hydrophilic over the entire area covered by the nozzle. This effect is caused by the incorporation of oxygen containing polar groups on the surface. It was also observed that depending on process parameters, the plasma treatment can extend even outside the area of the conical horn. The degree of surface modification depends on plasma dose while the treatment uniformity is determined mostly by the distance to the sample. Overall, a quite uniform surface modification was obtained over the entire area covered by the jet nozzle. Thus, the results suggest that by simply changing the jet geometry and choosing the right treatment parameters one can achieve a uniform treatment over an area whose size is determined by the horn diameter.

Glass-on-LiNbO3 heterostructure formed via a two-step plasma activated low-temperature direct bonding method

Lithium niobate (LiNbO3) crystal has been widely used in integrating optical and acoustic devices. However, direct bonding of LiNbO3 to Si-based materials is still a challenge due to the large coefficient of thermal expansion mismatches. In this paper, strong bonding strength of the LiNbO3/glass pair was obtained via the optimized O2 plasma activation followed by N2 plasma treatment. After the pre-bonding was accomplished at room temperature, the bonded pair was annealed at 150 °C for 12 h. A defect-free and tight bonding interface was confirmed by the scanning electron microscopy and transmission electron microscopy. Based on atomic force microscopy, water contact angle and X-ray photoelectron spectroscopy characterizations, both LiNbO3 and glass surfaces became smoother and more hydrophilic due to the densities of OH and N-related groups increased. Additionally, combined with the bonding strength obtained via different plasma activated processes, we demonstrated that the mechanism of the enhanced bonding strength could be attributed to N-related covalent bonds formed across the bonding interface. Furthermore, the excellent optical transmittance of LiNbO3/glass bonded pairs indicated this facile bonding process can meet the demand of high-performance glass-on-LiNbO3 devices.

Preparation and properties of waterborne epoxy resin modified by poly(meth)acrylates containing long fluorinated side chains

Two waterborne poly(meth)acrylates containing fluorinated side chains (PALF and PASF) were synthesized by conventional radical copolymerization. Then waterborne epoxy composites with hydrophobic surface were obtained through a phase-inversion emulsion technique, using the PALF and PASF acrylates as reactive surface additives. Contact angle measurements and X-ray photoelectron spectroscope were employed to characterize the surface properties and the results confirmed that the fluorine atoms in the longer fluorinated side chains migrated to the outmost layer more efficiently. The effect of the fluorinated content and the length of the fluorine side chain on thermal and bulk properties of the waterborne epoxy resin was investigated. With increasing the fluorinated content or the length of the fluorine side chain, the contact angles and thermal properties improved while the mechanical properties showed no deterioration.

Synthesis and Properties of PGS-Li Scaffold

Lithium ion-doped polyglycerol sebacate scaffold(PGS)-Li was synthesized by adding lithium ions to polyglycerol sebacate(PGS) during its crosslinking process due to the specific effects of lithium ions on periodontal ligament cells, cementoblasts and the eminent performance of PGS. The molecular mass, composition, structure, porosity, thermal properties, and hydrophilicity of the composite were characterized by gel permeation chromatography(GPC), Fourier transform infrared spectroscopy(FTIR), inductively coupled plasma optical emission spectrometer(ICP-OES), scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS), thermogravimetric analyzer(TGA) and contact angle measurments, and the degradation of the material was evaluated by in vitro degradation experiments. The biological activity of PGS-Li scaffold was detected by calcein-AM staining and cytotoxicity test. The results indicate that PGS-Li scaffold has been successfully synthesized, which has similar composition and structure to PGS, but slightly larger molecular weight. In addition, the porosity and pore size of PGS-Li scaffold basically meet the requirements of engineering scaffold materials and the seaffold shows better performance in terms of hydrophilicity and thermal stability than PGS. In vitro degradation experimental results show that the degradation rate of PGS-Li scaffold is higher than that of PGS. What’s more, the results of cytotoxicity test and cell staining show that there is no significant difference in the proliferation and cell morphology of cementoblasts.

Which low-fusing porcelain glaze treatment technique is better to promote a vitreous surface on Y-TZP ceramic?

OBJECTIVE: to evaluated the influence of two types of low-fusing porcelain glaze application on the surface of a zirconia ceramics stabilized by yttrium (Y-TZP).METHODS: Y-TZP specimens were divided into five groups (n=5) according the surface treatments: control (CO), no treatment was performed; application of a thin low-fusing porcelain glass layer by the powder/liquid technique (GPL); GPL followed by 10% hydrofluoric acid (HF) etching (GPL-HF); glaze spray application (GS); GS followed by 10% HF etching (GS-HF). Roughness measurements contact angle, x-ray diffraction, energy-dispersive spectroscopy (EDS) and scanning electron microscope (SEM) analysis were performed.RESULTS: ANOVA and Tukey tests revealed that GPL had significantly lower contact angle values than the other groups (GPL:50.31º; GPL-HF: 72.73º; GS-HF: 81.73º; CO: 96.48º; GS:101.30º; p=0.001). GPL-HF presented a significant higher roughness (Ra/Rq: 2658.0/3367.0 ηm; p=0.001) than the other groups (GPL: 872.1/1162.0 ηm; GS-HF: 383.0/603.6 ηm; GS: 303.4/391.3 ηm; CO:263.4/339.1 ηm). The X-ray diffraction analysis just tetragonal phase in all groups. EDS and SEM analysis show a highest amount of silica on GPL and GPL-HF surface.CONCLUSION: the application of the low-fusing porcelain glaze by the powder/liquid technique followed by the HF etching promoted a better surface to micromechanical and chemical adhesion.

Cytotoxicity and antibacterial efficacy of silver deposited onto titanium plates by low-energy ion implantation

Abstract

Contact X-ray Brachytherapy as an Adjunct to a Watch and Wait Approach is an Affordable Alternative to Standard Surgical Management of Rectal Cancer for Patients with a Partial Clinical Response to Chemoradiotherapy

AimsEmerging evidence suggests that contact X-ray brachytherapy (CXB) may increase the clinical complete response rate and durability when administered after standard chemoradiotherapy in patients with rectal cancer. The addition of CXB in partial responders is therefore probably cost-effective. The affordability of widening access to CXB in the UK, however, has not been evaluated. Materials and methodsDecision analytical modelling with Monte Carlo simulation was used to evaluate long-term costs for the management of patients with rectal cancers who were given a CXB boost when a clinical complete response was not initially achieved following chemoradiotherapy in order to facilitate a watch and wait approach. A third-party payer (National Health Service) perspective was adopted, probabilistic sensitivity analysis was carried out and a scenario analysis was performed to investigate the effect of the number of referral centres and number of patients treated with CXB. ResultsWe estimate that 818 (95% confidence interval 628–1021) patients per year are eligible for CXB as an adjunct to a watch and wait approach in England and Wales. As this management is less costly than surgical management for each individual patient, the more patients treated, the more affordable the technology. Even if as few as 125 patients are treated nationally in 15 centres, the cost of implementing this technology would be less than £4 million. If the average number of patients treated in each centre is 30, this technology would be cost saving within 5 years. ConclusionsThe cost of CXB is not prohibitive according to the National Institute for Health and Care Excellence threshold for implementation of new technology and may even be cost saving within 5 years compared with standard surgical management, depending on the uptake of the technology and the number of referral centres.

Julolidine-labelled fluorinated block copolymers for the development of two-layer films with highly sensitive vapochromic response

Fluorinated block copolymers composed of a polystyrene (Sx) first block and a polyacrylate second block carrying hydrophobic/lipophobic perfluorohexyl side chains (AF) were prepared by atom transfer radical polymerization (ATRP). Fluorescence emission properties were imparted to the copolymers by incorporation in the second block of a julolidine-based fluorescent molecular rotor (JCBF). The synthesized block copolymers were used as the fluorescent low-surface energy thin top-layer onto a polystyrene bottom-layer to produce novel two-layer film vapochromic sensors. Contact angle and X-ray photoelectron spectroscopy (XPS) measurements revealed that the two-layer film surfaces were hydrophobic and lipophobic at the same time and highly enriched in fluorine content as a result of the effective segregation of the perfluorinated tails to the polymer-air interface. The fluorescence intensity of the two-layer films decreased significantly when they were exposed to vapours of organic solvents, including tetrahydrofurane, chloroform, and trifluorotoluene. However, an AF content-dependent sensing behaviour was also observed, with the two-layer films containing the copolymer with the shorter fluorinated block giving a more rapid and almost quantitative decrease in fluorescence variation. Fluorescence emission of the films was also proved to vary with temperature. Both the vapochromic and thermochromic responses were reversible after successive solicitation cycles. The fluorescence variation of the two-layer films was much more marked than that of the corresponding PS/JCBF blend, thus providing a system potentially applicable as highly sensitive volatile organic compound (VOC) sensor, thanks to the active role of the fluorinated block in promoting the migration of the fluorophore to the outermost surface layers.

Rational construction of self-assembly azobenzene derivative monolayers with photoswitchable surface properties

Photo-responsive azobenzene (ABZ) derivatives with different end groups (R) as photoswitchable molecules were employed to construct self-assembled monolayers (SAMs) on silicon substrate by using 3-glycidoxypropyltrimethoxysilane (GPTS) as the bridging molecules. The assembly process was optimized by changing various parameters, including the type and concentration of ABZ derivatives, reaction time, etc. The obtained SAMs were fully characterized and evaluated using UV spectroscopy, atomic force microscope (AFM), elllipsometer, static contact angle and X-ray photoelectron spectroscopy (XPS). It is found that the end group property of azobenzene derivatives is critical to the obtained SAMs’ photoresponsive properties. Compared with hydrophobic compounds (4-(4′-aminophenylazo) benzoic acid, ABZ-CF3), the hydrophilic compounds (4-(4′-aminophenylazo) benzoic acid, ABZ-COOH) show excellent reversible photoswitching performance with a large contact angle change of 35° under optimized process, and the SAMs are removable by thermal treatment at 240°C in air for only 5min.

Novel planarization method of single-crystal diamond using 172 nm vacuum-ultraviolet light

We propose a novel planarization method for diamond substrates with 172 nm vacuum-ultraviolet (VUV) irradiation. To demonstrate the effectiveness of the proposed method, a polishing plate made of sapphire was used to polish diamond substrates with and without VUV irradiation under atmospheric conditions at room temperature. To interpret the planarization mechanism of the diamond substrate, the hydrophilic nature, cleanliness, and chemical-bonding state of the polishing plate before and after VUV irradiation were analyzed by a contact angle meter and X-ray photoelectron spectroscopy (XPS). The surface roughness and material removal rate were measured and evaluated by scanning white light interferometric microscopy and atomic force microscopy. The chemical-bonding state on the diamond surface before and after polishing were also analyzed by XPS. The experimental results show that VUV irradiation yields a hydrophilic and OH-terminated surface on the polishing plate, and give the effects in terms of the material removal rate and surface finish. The material removal rate with VUV irradiation (238.1 nm/h) was approximately seven times higher than that without VUV irradiation (33.3 nm/h). An atomically smooth diamond surface with a root-mean-square surface roughness below 0.1 nm can be prepared by polishing with VUV irradiation within 1.5 h.

Synthesis of hydrophobic polyanilines as a light-responsive liquid marble stabilizer

Hydrophobic and electrically conductive polyanilines were synthesized by single-step aqueous chemical oxidative polymerization in the presence of a perfluoroalkyl dopant, heptadecafluorooctane sulfonic acid. The resulting polyanilines were extensively characterized with respect to their morphology, surface/bulk chemical composition, wettability by water, (photo)thermal properties and conductivity. Scanning electron microscopy indicated that the polyanilines consisted of flocs of primary particles with sizes from submicrometer to a few hundreds of micrometers. Contact angle measurement and X-ray photoelectron spectroscopy confirmed the presence of perfluoroalkyl dopant on the surface of the dried polyanilines, which led to a water-repellent character. The conductivity of the pressed pellets increased from 3.2 × 10−3 S cm−1 to 1.4 S cm−1 as the dopant concentration used in the polymerization was increased, and the conductivities were higher than that of polyaniline synthesized in the absence of perfluoroalkyl dopant. The resulting polyaniline powder was able to function as a liquid marble stabilizer with photothermal properties. The liquid marble exhibited locomotion due to Marangoni propulsion on a planar water surface under irradiation with a near-infrared laser, and its transfer from water to solid surfaces was also achieved. The liquid marbles could be disrupted via an external stimulus to release their internal contents.

Preparation and antibacterial properties of hydrophobic Ag-loaded silica materials

ABSTRACTThe Ag-loaded hydrophobic silica (Ag/M-SiO2) materials were prepared by sol-gel method with tetraethylorthosilicate (TEOS) as precursor and methyltriethoxysilane (MTES) as hydrophobic modifier. Contact angles, X-ray diffraction and X-ray photoelectron spectra were used to characterize the as-prepared Ag/M-SiO2 materials. The antibacterial properties of the Ag/M-SiO2 materials were evaluated against Escherichia coli and Staphylococcus aureus. The results indicated that the appropriate calcination temperature of keeping the hydrophobicity of Ag/M-SiO2 materials is 300∼500°C. Ag element exists in Ag/M-SiO2 materials as the elemental form and hydrophobic Si-CH3 groups have been successfully introduced into the Ag/M-SiO2 materials. The qualitative and quantitative antibacterial experiments showed that the antibacterial activity increased with the increase of silver content. When the molar ratio of Ag/TEOS is increased to 0.10, the Ag/M-SiO2 materials showed good antibacterial dissolution and broad-spectrum antibacterial property.

Fabrication of Hydrophobic Nanocomposites Coating Using Electrospinning Technique For Various Substrate

Hydrophobic coating were fabricated using electrospinning technique on different substrates (glass, ceramic and metal), polymer solutions of (Si) were used in different range of composition for each solutions, also nano Al2O3 and nano TiO2 were used to fabricate nanocomposites. Contact angle, surface tension, viscosity, X-ray diffraction and FTIR were calculated for all specimens. (20%Si) owned a larger contact angle about (110.173°) for metal substrate and show a hydrophobicity for ceramic and glass substrate after coating with (20%Si). SEM showed the morphology of the surfaces and show that specimens has good surface morphology after coating with (20%Si/Al2O3) and (20%Si/TiO2). All results were discussed.

PO-1029: Contact x-ray brachytherapy for rectal cancer following chemoradiotherapy is cost-effective

PO-1029: Contact x-ray brachytherapy for rectal cancer following chemoradiotherapy is cost-effective

Highly hydrophilic and antibiofouling surface of zwitterionic polymer immobilized on polydimethylsiloxane by initiator-free atmospheric plasma-induced polymerization

In this study, we have successfully grafted zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer brushes (5–8 nm) on the silicone (polydimethylsiloxane, PDMS)-based contact lenses using “initiator-free” and atmospheric plasma-induced polymerization. Varied atmospheric plasmas (O2, N2 and Ar gas) were employed in the process of the polymerization of the zwitterionic polymer brushes on the silicone surfaces without the addition of any initiators. The morphology and characterization of the zwitterionic MPC-immobilized films were investigated using atomic force microscopy, contact angle (CA) measurements and X-ray photoelectron spectroscopy. MPC immobilizations will significantly improve the hydrophilicity of silicone contact lenses, and the CA of the MPC modified-silicone contact lenses will decrease to 50°–60°, compared with that of the pristine ones (CA: ~90°). Furthermore, the MPC modifications exhibit an anti-fouling capability (25–30% decrease of protein adsorption), which can avoid protein (fibrinogen and human serum bovine) adhesion that would contaminate the contact lenses. It maintains the great oxygen permeability (103 ± 5 Dk) and transmittance (T%) is still transparent and colorless after MPC grafted on the PDMS contact lens. Therefore, the immobilization of the MPC polymer brushes by atmospheric plasma-induced polymerization would be a rapid method to improve the hydrophilicity and enhance the anti-fouling capability of silicone based-contact lenses.

Surface Modification of Solution-Processed ZrO2 Films through Double Coating for Pentacene Thin-Film Transistors

We report the modification of surface properties of solution-processed zirconium oxide (ZrO2) dielectric films achieved by using double-coating process. It is proven that the surface properties of the ZrO2 film are modified through the double-coating process; the surface roughness decreases and the surface energy increases. The present surface modification of the ZrO2 film contributes to an increase in grain size of the pentacene film, thereby increasing the field-effect mobility and decreasing the threshold voltage of the pentacene thin-film transistors (TFTs) having the ZrO2 gate dielectric. Herein, the molecular orientation of pentacene film is also studied based on the results of contact angle and X-ray diffraction measurements. Pentacene molecules on the double-coated ZrO2 film are found to be more tilted than those on the single-coated ZrO2 film, which is attributed to the surface modification of the ZrO2 film. However, no significant differences are observed in insulating properties between the single-and the double-coated ZrO2 dielectric films. Consequently, the characteristic improvements of the pentacene TFTs with the double-coated ZrO2 gate dielectric film can be understood through the increase in pentacene grain size and the reduction in grain boundary density.

A cost-effectiveness analysis of contact X-ray brachytherapy for treatment of patients with a partial response to chemoradiotherapy for locally advanced rectal cancer

Background: A “watch and wait” approach (WW) may provide equivalent outcomes to initial radical surgery (RS) in patients with a clinical complete response (cCR) following neoadjuvant chemoradiotherapy (CRT). However, up to 80% of patients with locally advanced rectal cancer do not achieve a cCR. Contact X-ray Brachytherapy (CXB) enables high doses of radiation to be delivered directly to rectal cancers with minimal damage to adjacent tissue, and can be used in addition to external beam radiotherapy (EBRT) to increase cCR rate. The long-term cost-effectiveness of CXB has not been evaluated. Consequently, we aim compare the cost-effectiveness of WW with CXB and EBRT (WWCXB), to WW with EBRT alone (WWEBRT), and RS for patients with locally advanced rectal cancer.

Salvage surgery for local regrowth following external beam radiotherapy followed by contact X-ray brachytherapy and 'watch & wait' for rectal cancer. Do we compromise the chance of cure?

Background: Surgery is the standard of care for rectal cancer. However, it can be regarded as an over treatment for early stage screen detected rectal cancers. An alternative is to offer external beam radiotherapy (EBRT) +/- chemotherapy followed by contact X-ray brachytherapy (CXB) boost to reduce local regrowth which avoids initial extirpative surgery and a stoma. There is concern that this non-surgical approach may compromise the chance of cure if local regrowth develops. We present our experience on the outcomes following salvage surgery for local regrowth.

Depression Mechanism of Strontium Ions in Bastnaesite Flotation with Salicylhydroxamic Acid as Collector

Metal ions are widely present in flotation pulp. Metal ions change solution chemistry and mineral surface properties, consequently affecting mineral flotation. In this work, the effect of strontium ions on bastnaesite flotation with salicylhydroxamic acid (SHA) was investigated by microflotation tests, contact angle measurements, zeta-potential measurements, and X-ray photoelectron spectroscopy (XPS) analysis. Microflotation tests confirmed that the addition of strontium ions decreased bastnaesite floatability, compared with that in the absence of strontium ions. Contact angle measurements suggested that the pretreatment of strontium ions decreased SHA adsorption. Zeta potential measurements confirmed that the bastnaesite was depressed by the adsorption of positively charged strontium species, and the lower adsorption capacity of SHA onto the bastnaesite surfaces was obtained after modifying with strontium ions. XPS analysis demonstrated that strontium ions adsorbed onto the bastnaesite surfaces through the interaction between strontium ions and oxygen atoms of surface ≡ CeOH 0 groups. This occurrence hindered surface Ce sites which chelated with SHA and therefore, decreased bastnaesite floatability.