Unmodified Samples Research Articles

Effect of Hexagonal Boron nitride Nanopowder Reinforcement and Mixing Methods on Physical and Mechanical Properties of Self-Cured PMMA for Dental Applications.

We report for the first time on the effect of biocompatible hexagonal boron nitride (h-BN) nanopowder reinforcement with different concentrations on the structural and mechanical properties of fabricated self-cured polymethyl methacrylate (PMMA) based dental materials (GC UNIFAST III). A comparison among the structural and mechanical properties between hand and ultrasonic mixing is also presented. Fabricated specimens were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), micro indentation, and flexural strength techniques. The ultrasonic mixing method provides better sample textures of the composite as compared to hand mixing. It is found that XRD and IR intensity of the peaks increases with the increase of h-BN concentration due to nanocomposite formation. The additions of h-BN nanoparticles to the acrylic resin enhanced the hardness and the flexibility values of the composites. Independently of the mixing method used, adding h-BN nanopowder relatively increases the Vickers Hardness numbers (VH) and Flexural Strength (FS) of the unmodified materials. However, using ultrasonic mixing method combined with h-BN nanopowder increases VH numbers to 300% and FS values to 550% with respect to the unmodified sample made by hand mixing. The results obtained are very encouraging and will support future research in vivo, to confirm whether PMMA loaded with h-BN nanoparticles is an improvement compared to current dental restorative materials.

Rheology in the Presence of Carbon Dioxide (CO2) to Study the Melt Behavior of Chemically Modified Polylactide (PLA).

For the preparation of polylactide (PLA)-based foams, it is commonly necessary to increase the melt strength of the polymer. Additives such as chain extenders (CE) or peroxides are often used to build up the molecular weight by branching or even crosslinking during reactive extrusion. Furthermore, a blowing agent with a low molecular weight, such as carbon dioxide (CO2), is introduced in the foaming process, which might affect the reactivity during extrusion. Offline rheological tests can help to measure and better understand the kinetics of the reaction, especially the reaction between the polymer and the chemical modifier. However, rheological measurements are mostly done in an inert nitrogen atmosphere without an equivalent gas loading of the polymer melt, like during the corresponding reactive extrusion process. Therefore, the influence of the blowing agent itself is not considered within these standard rheological measurements. Thus, in this study, a rheometer equipped with a pressure cell is used to conduct rheological measurements of neat and chemical-modified polymers in the presence of CO2 at pressures up to 40 bar. The specific effects of CO2 at elevated pressure on the reactivity between the polymer and the chemical modifiers (an organic peroxide and as second choice, an epoxy-based CE) were investigated and compared. It could be shown in the rheological experiments that the reactivity of the chain extender is reduced in the presence of CO2, while the peroxide is less affected. Finally, it was possible to detect the recrystallization temperature Trc of the unmodified and unbranched sample by the torque maximum in the rheometer, representing the tear off of the stamp from the sample. Trc was about 13 K lower in the CO2-loaded sample. Furthermore, it was possible to detect the influences of branching and gas loading simultaneously. Here the influence of the branching on Trc was much higher in comparison to a gas loading.

Clean plasma modification for recycling waste plastic bags: From improving interfacial adhesion with wood towards fabricating formaldehyde-free plywood

It remains a great challenge to manufacture formaldehyde-free plywood, because of the wide application and cost advantage of formaldehyde-based adhesives. Herein, the waste plastic bag was recycled as an alternative to formaldehyde-based adhesives for manufacturing formaldehyde-free plywood. An industrial atmospheric dielectric-barrier-discharge plasma system was used to treat the plastic bag, in order to enhance the interfacial adhesion of the resultant plywood. The results suggested that plasma modification would excite oxygen and nitrogen into energetic particles and further ruptured the raw chemical bonds of plastic bag. Oxygen- and nitrogen-containing functional groups can be grafted, thus enhancing plastic bags’ surface polarity and wettability. As further supported by nanoindentation, the adhesion energy of plasma-modified plastic bag and poplar cell wall was elevated by 19.13% when compared to the unmodified sample, thus suggesting the improved interfacial adhesion and interfacial compatibility. Benefiting from that, formaldehyde-free plywood with a high bonding strength (0.82 MPa) was successfully fabricated. Shear strain in plywood distributed uniformly after plasma modification, suggesting the even distribution of adhesive and the enhanced bearing-load capacity of interface. This study paves a new way to effectively recycle plastic waste as an alternative to traditional adhesives for formaldehyde-free plywood manufacture.

Preparation and Study of Ni–Al–O System Cermet Composites with a Small Addition of MgAl2O4 Nanoparticles

This paper presents the results of obtaining and studying the structure and properties of cermets based on powders of aluminum oxide and nickel–aluminum alloy doped with 0.1 wt % of aluminum–magnesium spinel nanoparticles sintered by the electrospark method on a FCT-HP D 25 unit in argon at t = 1470°C for 30 min. The results of the NiAl–65Al2O3 charge TG and DSC analysis at up to 1300°C are presented. It is found that the MgAl2O4 spinel in the form of individual nanoparticles (60 nm) or aggregates (less than 700 nm) are present along the grain boundaries of the composite. Internal friction studies at t = 20–900°C and high-temperature X-ray phase analysis at t = 700, 800, and 900°C were carried out to describe the degradation mechanisms of the strength properties of the materials. The effect of nanoparticles on the internal friction of the composite within Δt = 20–900°C in the NiAl–65Al2O3–0.1MgAl2O4 system is shown. Potential mechanisms for cermet strength-property degradation with increasing temperature are discussed. It is suggested that the appearance of extrema on internal friction curves at high temperatures can be caused by shifted phase boundaries of intermetallic compounds and the oxide component due to different coefficients of thermal expansion (CTE). A positive effect of doping with spinel nanoparticles on the short-term heat resistance of cermets at t = 750°C is found. The study of short-term heat resistance at t = 750°C shows that the sample with nanoparticles is more stable than the unmodified sample, which can be associated with the influence of interfacial hardening zones formed around nanoparticles according to the Obraztsov–Lurie–Belov theory and a number of studies carried out on metal matrices.

Competitive Adsorption of Xylene and Toluene on Modified and Unmodified Sodium Bentonite Clay Mineral

Cetyltrimethylammonium bromide (CTAB) – modified and unmodified sodium bentonite were both used for the competitive adsorption of m-xylene and toluene from their aqueous solution. Infrared spectroscopy (IR) and expansion tests (adsorption capacity and Foster swelling) measurement were performed in order to evaluate the performance of the adsorbents. The FT-IR results indicated that the quaternary ammonium salts (CTAB) were intercalated between the layers of the sodium bentonite clay. The Foster swelling test results indicated that the affinity of CTAB was more in the treated clay for all other organic compounds tested. The result showed that modified sodium bentonite swelled more than the unmodified and the order of the swelling factor is; m- xylene > toluene > gasoline > diesel > kerosene > water. However, when the assay was performed under agitation, it yielded higher swelling capacity. The modified clay exhibited very high capacity of adsorption compare to unmodified samples. The m-xylene and toluene uptake follows a pseudo second order kinetics mechanism, suggesting that the rate determining step of adsorption involves the two adsorbates competitively adsorbed on the adsorbent sites. Therefore this organo-modified bentonite can be used for the removal of organics from polluted aqueous effluents.

Surface Modification of Staple Carbon Fiber by Dopamine to Reinforce Natural Latex Composite.

Carbon fiber significantly enhances the mechanical, thermal and electrical properties of rubber composites, which are widely used in aerospace, military, national defense and other cutting-edge fields. The preparation of a high-performance carbon fiber rubber composite has been a research hotspot, because the surface of carbon fiber is smooth, reactive inert and has a poor adhesion with rubber. In this paper, a high-performance rubber composite is prepared by mixing dopamine-modified staple carbon fiber with natural latex, and the mechanisms of modified carbon fiber-reinforced natural latex composite are explored. The experimental results show that the surface-modified staple carbon fiber forms uniform and widely covered polydopamine coatings, which significantly improve the interface adhesion between the carbon fiber and the rubber matrix. Meanwhile, when the concentration of dopamine is 1.5 g/L and the staple carbon fiber is modified for 6h, the carbon fiber rubber composite shows excellent conductivity, thermal conductivity, and dynamic mechanical properties, and its tensile strength is 10.6% higher than that of the unmodified sample.

Experimental investigation of effect of PP/SBR polymer blends on the moisture resistance and rutting performance of asphalt mixtures

Prevention of surface failure in flexible pavements and application of durable asphalt mixtures leads to the design of a high-quality pavements and improvement in safety and confidence of drivers. Moisture susceptibility, or stripping, is a type of failure which results in the separation of binder and aggregate in asphalt mixtures, and consequently intensifies other kinds of failures including fatigue and rutting. Improvement in properties of asphalt mixtures’ components can minimize the failures of road pavements. In such a context, binder modification with polymers is known as an effective method which enhance mixtures’ strengths against common damages. In This study, a blend of two inexpensive polymers has been suggested as binder additive to modify the performance of the asphalt mixtures against moisture. For this purpose, styrene-butadiene-rubber (SBR) and polypropylene (PP) are combined by different ratios 70:30, 50:50 and 30:70, then each of polymer blends were added in 60–70 binder with 3, 4 and 5% of the weight of the binder. Since the styrene butadiene styrene (SBS) polymer is a well-known and effective additive in term of moisture susceptibility of flexible pavements, mixtures containing modified binders with blended polymer (SBR/PP) were compared to mixtures containing SBS modified bitumen with 4% and 5% polymer content. In all samples, 1.5% Nanoclay (by mass) was utilized to increase the stability of polymers in the binder. To evaluate the moisture susceptibility and permanent deformation, Texas boiling test, Marshall stability, Resilient modulus, Indirect tensile strength (ITS) and Dynamic creep tests were carried out on mixture samples modified by polymer blends, mixtures modified by SBS and also an unmodified sample (control mixture). As the experimental results show, by increasing SBR content in asphalt mixtures, the performance of the samples against moisture failure has been improved. Furthermore, among all tested samples, the asphalt mixture containing 5% polymer blends with 70% of SBR Shows the best performence which can be introduced as an economical alternative for mixture with high dosage of SBS.

Anti-ultraviolet properties of β-cyclodextrin-grafted cotton fabrics dyed by broadleaf holly leaf extract

The aim of the study was to investigate the anti-ultraviolet properties of β-cyclodextrin-grafted cotton fabrics dyed with broadleaf holly leaf extract. Flavonoids were extracted from broadleaf holly leaf by maceration and a stoichiometry of 1:1 inclusion complex with β-cyclodextrin was formed. Characterized by the fluorescence spectrum and ultraviolet spectrophotometry, the fluorescence intensities and ultraviolet absorption of the macerated extract were enhanced by increasing the amount of cyclodextrin. Cotton fabrics were grafted with β-cyclodextrin through a crosslinking reaction based on citric acid in the presence of sodium hypophosphite then dyed with the macerated extract of broadleaf holly leaf used as a natural ultraviolet absorbent. The anti-ultraviolet property of fabrics dyed by a macerated extract was characterized in terms of the ultraviolet protection factor. It was noted that the cotton fabrics grafted with β-cyclodextrin exhibit enhanced anti-ultraviolet and wrinkle recovery properties compared to the unmodified samples and show an excellent durability against 30 washing cycles, accompanied by a loss of tensile strength.

Sulfonated activated carbons as potential catalysts for biolubricant synthesis

In this study, sulfonated activated carbons have been prepared, under different conditions, with the purpose of evaluating the effect of the nature and amount of sulfonic surface groups on the esterification reaction of free fatty acids (FFA) with different long-chain alcohols. The synthesized catalysts were characterized using different techniques and 1H NMR was used for monitoring the reaction products. The modifications of the surface functionalities were assessed by X-ray Photoelectron Spectroscopy (XPS) and Thermogravimetric analysis (TGA), while changes in the porous network and morphology of the samples were evaluated before and after the treatment of the original activated carbon sample. XPS results showed the presence of two types of sulfur, one from thiophenic sulfur (present on all materials, including the unmodified sample), and the other from sulfonic groups (SO3H), at 168 eV (present only in the modified samples). These catalysts were applied in the esterification reaction and presented excellent catalytic performances, while the original activated carbon exhibited conversions similar to reactions without any catalyst. On the other hand, the conversion of fatty acids when using the modified carbons improves significantly with values up to ∼100 % to mono alcohols and 70 % to trimethylolpropane.

A Multi-Method Approach for Quantification of Surface Coatings on Commercial Zinc Oxide Nanomaterials.

Surface functionalization is a key factor for determining the performance of nanomaterials in a range of applications and their fate when released to the environment. Nevertheless, it is still relatively rare that surface groups or coatings are quantified using methods that have been carefully optimized and validated with a multi-method approach. We have quantified the surface groups on a set of commercial ZnO nanoparticles modified with three different reagents ((3-aminopropyl)-triethoxysilane, caprylsilane and stearic acid). This study used thermogravimetric analysis (TGA) with Fourier transform infrared spectroscopy (FT-IR) of evolved gases and quantitative solution 1H nuclear magnetic resonance (NMR) for quantification purposes with 13C-solid state NMR and X-ray photoelectron spectroscopy to confirm assignments. Unmodified materials from the same suppliers were examined to assess possible impurities and corrections. The results demonstrate that there are significant mass losses from the unmodified samples which are attributed to surface carbonates or residual materials from the synthetic procedure used. The surface modified materials show a characteristic loss of functional group between 300–600 °C as confirmed by analysis of FT-IR spectra and comparison to NMR data obtained after quantitative release/extraction of the functional group from the surface. The agreement between NMR and TGA estimates for surface loading is reasonably good for cases where the functional group accounts for a relatively large fraction of the sample mass (e.g., large groups or high loading). In other cases TGA does not have sufficient sensitivity for quantitative analysis, particularly when contaminants contribute to the TGA mass loss. X-ray photoelectron spectroscopy and solid state NMR for selected samples provide support for the assignment of both the functional groups and some impurities. The level of surface group loading varies significantly with supplier and even for different batches or sizes of nanoparticles from the same supplier. These results highlight the importance of developing reliable methods to detect and quantify surface functional groups and the importance of a multi-method approach.

The effect of coal bottom ash as a replacement on subgrade strength

Coal Bottom Ash (CBA) which is one of coal combustion product (CCPs) obtained from thermal power plant will negatively affect the ecological system which human health ultimately depends on. The increase in demands for landfill requirements and the limitations natural aggregates is quite disturbing unless the new alternative to cut the usage of natural aggregates is found. Therefore, this paper present the laboratory investigation work to improve the strength of subgrade by the replacement of CBA with different percentage varies (0%, 15%, 30% & 40%) by weight. California Bearing Ratio (CBR) test is carried out to obtain the optimum percentage replacement CBA and then some physical which are particle size distribution, Atterberg limit test, specific gravity test and compaction test also carried out to observe the mechanical properties of optimum sample. The optimum percentage of CBA replacement obtained is 40.65% at 30% CBA replacement compared to 17.99% of subgrade soil alone. The moisture dry-density of unmodified soil sample is higher (1.99Mg/m3, 15.34%) than optimum sample (1.95Mg/m3, 10.2%). Moreover, 30% CBA replacement resulted in intermediate plasticity than the subgrade soil which is highly plastic. In conclusion, strength of subgrade soil is highest at 20-30% of CBA replacement.

MINERAL-BASED MAGNETIC NANOCOMPOSITE SORBENTS

The article is devoted to the synthesis of mineral-based magnetic nanocomposite sorbents and the study of the influence of modification by magnetite and molybdenum disulfide on the structural-sorption and surface properties of native saponite clay. Modification of native saponite clay with nanoscale magnetite increases the specific surface area and changes pore’s distribution of the original clay from monomodal to bimodal. Next modification of magnetic saponite by micro-sized and nano-sized molybdenum disulfide results in blocking of the secondary porous structure (bimodality disappears of magnetic saponite), but it is increasing the specific surface area. It was found that the sorption activity of modified and unmodified saponite in the region of low concentrations of cationic and anionic dyes (Methyl blue and Congo red) is almost the same. The study of Congo red dye adsorption from highly concentrated solutions showed significant differences in the sorption activities of modified and unmodified saponite samples: the largest sorption capacity characteristic of ternary composites (saponite modified by magnetite and by nano-sized molybdenum disulfide). These ternary composites had in 62 times more activity than native saponite clay and 10 times more than magnetic saponite. It is established that all the samples are characterized by basic properties, but the sample of native saponite modified by magnetite and nano-sized molybdenum disulfide has the largest number of active centers (both acidic and basic character). Thus, it is shown that the modification of the native saponite clay significantly affects not only the texture-sorption but also the surface properties of the native saponite clay.

Mechanical Properties and Conductivity of Low-Pressure Die-Cast 319 Aluminum Prepared with Hot Isostatic Pressing, Thermal Treatment, or Chemical Treatment

Low-pressure die-cast (LPDC) 319 Al alloy is commonly processed with hot isostatic pressing (HIP), heat treatment, and chemical eutectic silicon modification for advanced automotive applications. Yet, the microstructure can be similarly influenced by each of these processes, which may obscure their isolated benefits. Hence, this study aimed to differentiate their effects by processing step blocks of LPDC 319 alloy with either a HIP or ambient-pressure heat treatment, each for 2 h at 500 °C, or with strontium additions up to 150 ppm. Both chemical and thermal modifications of eutectic silicon were found to effectively improve alloy conductivity. However, the potential benefits of strontium to alloy strength and hardness were offset by the decreases in density associated with the addition. In contrast, the as-cast, unmodified samples featured relatively high densities, although this limited the ability of the HIP treatment to reduce porosity. With identical temperatures and heating times, both the HIP and heat treatment promoted comparable Al2Cu dissolution and silicon spheroidization. Accordingly, both treatments generally improved hardness and strength, and increased thermal and electrical conductivities by up to 12.5%. Thus, these processing parameters can each contribute to the development of enhanced engineering components individually, thereby reducing the need for their combined application.

Non-RGD peptide H-ckrwwkwirw-NH2 grafting accentuates antibacterial and osteoinductive properties of biopolymer coating

ABSTRACT A coating on the surfaces of metallic implants to promote bone cell integration as well as prevent infection is highly desired for orthopedic surgeries. A novel antibacterial peptide was grafted onto an osteoinductive coating and the modified coating was tested for its antibacterial properties and biocompatibility with bone cells in vitro. A layer of chitosan hydrogel was chemically attached to the surface of a medical-grade titanium alloy and a novel non-RGD peptide (H-ckrwwkwirw-NH2) was grafted on top of the coating through chemical cross-linking. The composite layer was tested for its surface wettability (contact angle), composition (energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy), antibacterial property, and bone cell biocompatibility. The successful grafting of the peptide onto the coating was confirmed by the increase of contact angle and nitrogen content (both p < .05) on the surface due to the presence of the hydrophobic amino acids. The modified coating successfully reduced the growth of Gram negative and positive (E. coli and S. aureus) bacteria by 74.2% and 52.4%, respectively (p < .01). The coating did not show any sign of cytotoxicity and unexpectedly improved osteoblast proliferation and mineralization compared to unmodified samples (all p < .01). An antimicrobial peptide successfully grafted onto the chitosan coating to enhance its bactericidal function. This non-RGD peptide, after chemical modification, not only preserved its bactericidal activity but also improved the biocompatibility of the coating.

Influence of in-house produced biochar on geotechnical properties of expansive clay

The current study aims to explore geotechnical properties of expansive soil amended with in-house produced biochar. Biochar was produced in-house using slow pyrolysis (at constant temperature of 500 °C) of commonly available Prosospis Juliflora (invasive weed) in a muffle furnace. This study also motivates alternative use of Prosospis Juliflora, whose reduction can help to minimize transmission of malaria and also threat to bio-diversity. The biochar was uniformly mixed with expansive black cotton soil at 5% and 10% content. Both basic and geotechnical properties (CBR and unconfined compressive strength) was determined for modified and unmodified soil samples. Based on results, it can be concluded that the plasticity index of an expansive soil is reduced significantly with an increase in biochar content. On the other hand, change in shrinkage limit was negligible. There is an increase in unconfined compressive strength and also reduction in free swell index of expansive soil amended with biochar. This is despite the significantly lower specific gravity and higher porous structure of biochar particles. The result is contrary to application of biochar in sandy soils in literature. The possible mechanism could be due to formation of bonds between negatively charged surface functional groups of biochar and positively charged ions of an expansive soil.

Study of UHMWPE Fiber Surface Modification and the Properties of UHMWPE/epoxy Composite.

Ultra-high molecular weight polyethylene (UHMWPE)/epoxy composites with excellent adhesive properties were prepared by forming an interface membrane on the UHMWPE fiber surface. The interface membrane of the UHMWPE fiber and epoxy resin was polymerized by an aldol condensation between polyvinyl alcohol (PVA) and glutaraldehyde. Different surface treatment methods of UHMWPE fibers were optimized and the two-step PVA-glutaraldehyde condensation (Corona-PG-2S) method is the best. The interfacial adhesion between UHMWPE fiber and epoxy resin was enhanced, and the adhesive properties of the composite were improved. X-ray photoelectron spectroscopy (XPS) and energy dispersive spectrum (EDS) results of the fiber treated by Corona-PG-2S shows that the surface oxygen content was up to 25.0 wt %, with an increase of 17.3 wt % compared with the surface oxygen content of unmodified UHMWPE fiber, which indicated that the surface polarity was greatly enhanced. The adhesive properties were improved by improving the polarity of the surface. The peel strength, ultimate cohesive force, tensile strength and flexural strength of the composite treated by Corona-PG-2S were greatly increased to 262.8%, 166.9%, 139.7%, 200.6% compared with those of unmodified samples. The composite prepared by Corona-PG-2S had excellent adhesive properties, demonstrating that the Corona-PG-2S method plays a major role in significantly improving the composite adhesive properties.

Study of the Topography and Properties of Surface Layers in Frost-Resistant Rubbers Modified with Carbon Nanotubes

The possibilities of creating new types of frost-resistant rubbers by using carbon nanotubes as a filler (modifier) for an elastomeric base (epichlorohydrin rubber) are studied. Samples with a nanotube content of 1 and 10% and the initial unmodified sample are compared. The initial samples and the samples after tribological tests are studied by the method of scanning electron microscopy (with elemental analysis). The method of scanning probe microscopy is used to study the surface topography and the physicomechanical properties (modulus of elasticity and adhesion). The addition of carbon nanotubes to the elastomer is shown to stabilize its composition and to result in structuring of the elastomeric base. The investigation of sample slices prepared after tribological testing makes it possible to distinguish several areas: thin “surface” (a thickness of 10–15 μm) and “near-surface” layers. Strong element redistribution is recorded, i.e., the concentration of sulfur and zinc increases significantly on the surface. It is shown that during tribological tests, the main changes occur mostly in the surface layer, while the near-surface layer does not transform so considerably. It is established that the addition of carbon nanotubes leads to an increase in the modulus of elasticity in the near-surface layers.

Evaluation of Irvingia kernels extract as biobased wood adhesive

Irvingia tree species have been earmarked for domestication in many countries due to their potential as raw materials for various applications, which include biodiesel, cosmetics, perfume, soap, etc. Presently, there is no information on the utilization of kernel seed extract as a potential source of green wood adhesive. This study is focused on investigating the properties of adhesives produced from kernel seeds of two Irvingia wood species i.e. Irvingia gabonensis (IG) and Irvingia wombolu (IW), as well as investigating the improved properties derived from the effect of modification using a few selected modifying agents including glutaraldehyde, glyoxal, epichlorohydrin (EPI) and an acid/base type process modification. Polyethylene (PE) was used along with the glutaraldehyde, glyoxal and epichlorohydrin modifiers in the modification process. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) were conducted to study the effect of modification on adhesive properties. The glycosidic carbon of the unmodified extracts and that of the EPI modified sample were not sensitive to chain conformations. Principal components (PC) 1 and 2 explained 85.19 and 9.54%, respectively, of the total variability in FTIR spectra among the modified and unmodified adhesives. The unmodified samples for IG and IW exhibited one peak with crystallization temperatures of 18.7 and 14.4 °C, respectively, indicating only one component exhibits some low degree crystallinity. The adhesive properties of the modified extracts were tested on wood veneers according to ASTM standard. The shear strength of the modified adhesives ranged from 1.5 to 3.93 MPa and 1.7 to 4.05 MPa for IG and IW, respectively. The modified samples containing PE showed marked improvement in the shear strength. The highest values were about 63% higher than the shear strength of unmodified samples with least shear strength. The results indicated that the modification of Irvingia-based adhesives had a great contribution to their performance as natural wood adhesives.

The transparent device of CdS quantum dots modified Cu2O/ZnO orderly nano array p-n junction towards the enhanced photovoltaic conversion

The transparent device of CdS QDs modified Cu2O/ZnO nano array p-n junction is prepared via simple continuous magnetron sputtering method and chemical deposition. The p-n junction device with good stability exhibits decent transparency of about ∼80% in visible light, and evident photovoltaic response enhancement of about ∼100 times than the unmodified sample, that can be mainly attributed to the CdS QDs with high QY can improve the visible light response, the p-n junction with self-photovoltage and the ZnO order arrays can improve the transport of the photon-generated carriers.

Sulfur Hexafluoride (SF6) Plasma Treatment of Medical Grade Poly(methyl methacrylate)

Medical-grade poly(methyl methacrylate) (PMMA) is widely employed in the fabrication of intraocular lenses (IOLs), but suffers from opacification, a postoperative complication that leads to the failure of the implanted intraocular lenses. The opacification occurs when inorganic-based deposits accumulate on the surface of the IOL and are prevalent in hydrophilic materials. Here, the surface of medical-grade PMMA has been fluorinated by sulphur hexafluoride (SF6) plasma treatment to increase surface hydrophobicity thus improving the material lifetime in optical applications. Hydrophobic properties of the treated PMMA were investigated by means of contact angle measurements, while chemical modification was assessed by X-ray Photoelectron Spectroscopy (XPS) and Attenuated Total Reflectance Fourier Transform Infrared (ATR/FTIR) spectroscopy. Surface morphological changes due to possible etching effects were investigated by Atomic Force Microscopy (AFM). The transparency of the treated PMMA was assessed by UV/VIS spectroscopy. Finally, the influence of the plasma treatment on the inorganic salts deposition was investigated by immersion in Simulated Aqueous Humour (SAH), followed by XPS analysis. The modified samples showed less deposition on the surface than the unmodified sample, moreover, a decrease of the transmittance in the UV-violet range (300–430 nm) was detected, open the possibility of interesting applications of this treatment for the creation of a UV filter in ophthalmic optical devices.