Low-energy Method Research Articles

Development, stability and in vitro delivery profile of new loratadine-loaded nanoparticles

Purpose: Loratadine is used as antihistaminic without side effects in nervous systems. This drug is a weak base and it is absorbed from the intestine. The nitrogen of the pyridine ring is protonated in the stomach affecting the oral bioavailability. The aim of this paper was obtaining, characterize and evaluate the release profiles and the stability of a gastroresistant loratadine nanosuspension. Methods: The nanosuspension was prepared by the solvent displacement evaporation method, using three different polymers (Eudragit® L 100 55, Kollicoat® MAE 100P and PEG 4000) and Polysorbate 80. Dynamic Light Scattering was used for evaluating the particle size (PS), zeta potential, and conductivity of the nanosuspension. Loratadine release profiles were evaluated in simulated gastrointestinal fluids. The shelf and accelerated stability were assessed during three months. Results: Nanosuspension particle size was 45.94±0.50nm, with a low polydispersion index (PdI, 0.300). Kollicoat® MAE 100P produced a hard and flexible coating layer. In simulated intestinal fluids, the 100 percent of loratadine was released in 40min, while in simulated stomach fluids the release was lesser than 5%. Nanosuspension presented a good physicochemical stability showing a reduction in PS and PdI after three months (43.29±0.16 and 0.250; respectively). Conclusions: A promissory loratadine nanosuspension for loratadine intestinal delivery was obtained, by using a low energy method, which is an advantage for a possible scale up for practical purpose.

Antifungal activity of nano emulsions of neem and citronella oils against phytopathogenic fungi, Rhizoctonia solani and Sclerotium rolfsii

Biopesticides are considered to be safe, target specific, biodegradable and eco-friendly. These, especially Azadirachta indica A. Juss. (neem) based biopesticides, are mainly used as emulsified concentrate (EC). There is growing interest in nano emulsions based on phytochemical mixtures due to their better efficacy compared to conventional biopesticides. A. indica seed oil and Cymbopogon nardus (L.) Rendle (Citronella) oil are known to have pest control properties. However, their utilization is often restricted due to relatively low water solubility. This drawback can be overcome by encapsulating oils in oil-in-water (O/W) emulsions or nano emulsions using low or high energy methods. In this study, various nano emulsions of crude neem and citronella oils with surfactants were developed and characterised by Dynamic Light Scattering (DLS) and Transmission Electron Microscope (TEM). Composition of various ingredients of nano emulsions was standardised. TEM study showed the spherical shape of neem and citronella oil nano emulsions. The average size of droplets of neem nano emulsion (NNE) with different percentage of citronella oil ranged from 11.23±3.86nm to 17.80±4.52nm while that of citronella nano emulsion (CNE) with different percentage of neem oil ranged from 8.12±2.80nm to 12.04±3.74nm. It was found that increase in surfactant ratio to neem oil or citronella oil decreases the size of droplets in nano emulsions. Further, in vitro antifungal study of against Rhizoctonia solani and Sclerotium rolfsii was carried out by poisoned food technique. Results showed that neem nano emulsion 10 (NNE10) and citronella nano emulsion 10 (CNE10) were most active against R. solani (ED50 13.67mgL−1 and 25.64mgL−1) and S. rolfsii (ED50 14.71mgL−1 and 20.88mgL−1). The standardization of the composition and development of citronella essential oil and neem oil based nano emulsions and their antifungal activity against these two fungi has been reported for the first time.

Traversing the Skin Barrier with Nano-emulsions.

In recent years, colloidal delivery systems based on nano-emulsion are gaining popularity; being used for encapsulation and delivery of many drugs. This review therefore aims at summarizing various methods of nano-emulsion formulation and their use as a topical and transdermal delivery vehicle for a number of active pharmaceutical ingredients from different pharmacological classes. This article represents a systematic review of nano-emulsions for topical and transdermal drug delivery. A vast literature was searched and critically analysed. Nano-emulsions are thermokinetically stable dispersion systems, which have been used in topical and transdermal delivery of a number of pharmaceutically active compounds. Nano-emulsions have a narrow droplet size range with tuneable surface properties, which make them an ideal delivery vehicle. Nanoemulsions have a number of advantages over conventional emulsions, including easy preparation using various low and high energy methods, optical transparency, high solubilisation capacity, high stability to droplet aggregation and the ability to penetrate the skin; thus allowing the transdermal delivery of drugs. This review indicated that nano-emulsions are promising vehicle for entrapping various drugs and are suitable for traversing the skin barrier for systemic effects.

Preparation of water-in-diesel oil nano-emulsion using nonionic surfactants with enhanced stability and flow properties

ABSTRACTFormation of water-in-diesel oil (w/o) nano-emulsion has been achieved by a low-energy emulsification method by stabilizing a new combination of nonionic sorbitan esters surfactants, that is PEG20-sorbitan monostearate and sorbitan monooleate in mixed proportions. Different combinations of the surfactants (T6 + S8) have been tested and the best possible combination of mixed surfactants is found at a surfactants ratio of 35:65 (wt/wt) for T6:S8 at hydrophile–lipophile balance (HLB) = 8.01, which resulted in smaller droplet size of 44.87 nm. A phase diagram study is performed to identify the zones of formation of transparent, translucent, and opaque emulsions (44 nm < droplet size < 700 nm). The mechanism responsible for the instability of emulsion is explained by Ostwald ripening, with inference describing a decrease in particle size with the Ostwald ripening rate. In case of nano-emulsion of droplet size 64.28 nm, the Oswald ripening rate is found as 0.0874 × 10−27 m3 · s−1. Comparison of Ostwald ripening rate with other sets of surfactants obtained by different authors showed the lowest rate among them, indicative of enhanced stability. A rheological study of the tested set of nano-emulsions depicts the Newtonian behavior (1.0371 ≤ n ≤ 1.0826) over a wider range of shear rates (10–1000 s−1) at different temperatures (25–40°C).

A General Route for Nanoemulsion Synthesis Using Low-Energy Methods at Constant Temperature

The central dogma of nanoemulsion formation using low-energy methods at constant temperature-popularly known as the emulsion inversion point (EIP) method-is that to create O/W nanoemulsions, water should be added to a mixture of an oil and surfactant. Here, we demonstrate that the above order of mixing is not universal and a reverse order of mixing could be superior, depending on the choice of surfactant and liquid phases. We propose a more general methodology to make O/W as well as W/O nanoemulsions by studying the variation of droplet size with the surfactant hydrophilic-lypophilic balance for several model systems. Our analysis shows that surfactant migration from the initial phase to the interface is the critical step for successful nanoemulsion synthesis of both O/W and W/O nanoemulsions. On the basis of our understanding and experimental results, we utilize the reverse order of mixing for two applications: (1) crystallization and formulation of pharmaceutical drugs with faster dissolution rates and (2) synthesis of alginate-based nanogels. The general route provides insights into nanoemulsion formation through low-energy methods and also opens up possibilities that were previously overlooked in the field.

Influence of polymer concentration on the properties of nano-emulsions and nanoparticles obtained by a low-energy method

This study concerns the effect of polymer content on the properties of nano-emulsions formulated by the PIC low-energy method and on the nanoparticles prepared from nano-emulsions by solvent evaporation. The region of nano-emulsion formation, droplet size and stability as a function of polymer content were investigated. Nano-emulsions were formed in a wide range of oil-to-surfactant weight ratios (Ros) and water contents higher than 45%. For nanoparticles, droplet size, stability, encapsulation efficiency, pH, drug release and cytotoxicity effect were evaluated as a function of polymer content. Nano-emulsion droplet size (Rh=8–75nm) and nanoparticle size (Rh=8–55nm) increase with the polymer content. No desestabilization process such as creaming or sedimentation was observed by light transmittance/backscattering neither in nano-emulsions nor in nanoparticle dispersions. The morphology and size of nano-emulsions and nanoparticles were comfirmed by Cryo-TEM and TEM techniques, respectively. The pH of nanoparticle dispersions was in the range of 5–6.5 during the studied experimental time (7days), an indication of no polymer degradation. Moreover, Dexamethasone (DXM) encapsulated in the polymeric nanoparticles (0.18wt% DXM in the oil phase of the template nano-emulsion) did not modify the nanoparticle size. No effect of polymer concentration was found in the encapsulation efficiency (close to 90%) of DXM. In vitro drug release studies indicated Fick’s diffusion as the main drug release mechanism from the nanoparticle to the receptor solution. DXM loaded and non-loaded nanoparticles showed cell viability higher than 70%. This study reports a promising system to be used as template for polymeric nanoparticle preparation suitable for biomedical applications.

Preparation of stable tea seed oil nano-particle emulsions by a low energy method with non-ionic surfactants

Tea seed oil nano-particle emulsions were prepared. Non-ionic surfactants containing Tween 80 and Span 80 (1:1, w/w) were mixed with propanol (3-9:1, w/w) to give Smix, which was thereafter mixed with tea seed oil. The mixture was titrated with water at 150 rpm to give clear or bluish and bluish-white emulsions. Twelve nano-particle emulsions with 64.64 to 72.73% Smix, 16.66 to 27.27% oil and 9.09 to 16.67% water with particle sizes between 207.00 to 430.10 nm, PDI of 0 to 0.4, ζ-potential of -42.00 to -49.63 mV, pH of 7.04 to 7.32 and 151.33 to 241.93 cps, were stable following an accelerated stability test and long term storage at room temperature and 4 and 45 ºC for 90 days, although one system (16.66% oil and 66.67% Smix) was separated. This nano-particle emulsion formulation is concise and feasible for an industrial development of topical products containing tea seed oil.

Development of nanoemulsion from Vitex negundo L. essential oil and their efficacy of antioxidant, antimicrobial and larvicidal activities (Aedes aegypti L.).

It is believed that nanoemulsions were emerged as a promising candidate to improve the qualities of natural essential oil towards antimicrobial and insecticidal applications. In the present study, we have focused on the encapsulation of Vitex negundo L. leaf essential oil using Polysorbate80 for its different biological activities including antioxidant, bactericidal and larvicidal activity against dengue fever vector Aedes aegypti L. Initially, the nanoemulsion was prepared by low energy method and droplet size of the formulated nanoemulsion was characterizedby using Dynamic Light Scattering analysis. The freshly prepared V. negundo essential nanoemulsion was observed with the mean droplet size of below 200nm indicating its excellent stability. Further, the larvicidal activity of essential oil and nanoemulsion with various concentrations (25, 50, 100, 200 and 400ppm). The larvicidal activities were tested 2nd and 3rd instar larval mortality rate that was observed against the 12 and 24 h exposure period. After a 12 h exposure period, the larvicidal activities of 2nd instar larva were observed as essential oil (73.33±1.88), nanoemulsion (81.00±0.88) and the larvicidal activities of 3rd instar larva were displayed essential oil (70.33±2.60) and nanoemulsion (79.00±3.70). Likewise, after a 24 h exposure period, the larvicidal activities of 2nd instar larva were observed as essential oil (90.30±2.15), nanoemulsion (94.33±1.20) and the larvicidal activities of 3rd instar larva were essential oil (80.66±0.66) and nanoemulsion (93.00±1.25) respectively. We finally concluded that the developed plant-based emulsion essential oil systems were thermodynamically stable. Owing to its improved bioavailability and biocompatibility, formulated nanoemulsion can be used in various biomedical applications including drug delivery as well as disease transmitting mosquito vector control. Graphical abstract ᅟ.

Experimental Investigation on the Fatigue Life of Ti-6Al-4V Treated by Vibratory Stress Relief

Vibratory stress relief (VSR) is a highly efficient and low-energy consumption method to relieve and homogenize residual stresses in materials. Thus, the effect of VSR on the fatigue life should be determined. Standard fatigue specimens are fabricated to investigate the fatigue life of Ti-6Al-4V titanium alloy treated by VSR. The dynamic stresses generated under different VSR amplitudes are measured, and then the relationship between the dynamic stress and vibration amplitude is obtained. Different specimen groups are subjected to VSRs with different amplitudes and annealing treatment with typical process parameters. Residual stresses are measured to evaluate the stress relieving effects. Finally, the fatigue behavior under different states is determined by uniaxial tension–compression fatigue experiments. Results show that VSR and annealing treatment have negative effects on the fatigue life of Ti-6Al-4V. The fatigue life is decreased with the increase in VSR amplitude. When the VSR amplitude is less than 0.1 mm, the decrease in fatigue limit is less than 2%. Compared with specimens without VSR or annealing treatment, the fatigue limit of the specimens treated by VSR with 0.2 mm amplitude and annealing treatment decreases by 10.60% and 8.52%, respectively. Although the stress relieving effect is better, high amplitude VSR will lead to the decrease of Ti-6Al-4V fatigue life due to the defects generated during vibration. Low amplitude VSR can effectively relieve the stress with little decrease in fatigue life.

Constructing a Heterostructural LiNi0.4Mn1.6O4-δ Material from Concentration-Gradient Framework to Significantly Improve Its Cycling Performance.

A heterostructural LiNi0.35Mn1.65O4-δ-LiNi0.5Mn1.5O4 was achieved via constructing the concentration-gradient material with an average composition of LiNi0.4Mn1.6O4-δ. The as-obtained samples were characterized by cross-sectional scanning electron microscopy and energy dispersive X-ray spectrometry, and it was found that the core material LiNi0.35Mn1.65O4-δ is encapsulated completely by a concentration-gradient shell with the outmost layer of LiNi0.5Mn1.5O4. Demonstrated by high resolution transmission electron microscopy and X-ray photoelectron spectroscopy analysis with a low-energy Ar neutral beam etching method, the structurally stable P4332 phase on the surface coordinates the high conductive Fd3̅m phase in the bulk without any detectable interface. At room temperature, the heterostructural samples deliver the initial discharge capacity of 145.1 mAhg-1 at 1 C, close to the theoretical capacity, and the capacity retention after 300 cycles was up to 96.5% of the first discharge capacity. Moreover, it shows excellent rate capability with discharge capacity of 144.3 mAhg-1 at 10 C and significantly improved cycling stability with capacity retention of 85.51% over 50 cycles between 3.0 and 4.95 V at 55 °C. The as-obtained material with coordination of two crystallographic structure domains is a promising cathode to develop high energy, high power, long lifespan, and low cost lithium-ion batteries.

Natural herbicide activity of Satureja hortensis L. essential oil nanoemulsion on the seed germination and morphophysiological features of two important weed species

The aim of the present study was to obtain an oil/water (O/W) nanoemulsion (NE) containing garden savory (Satureja hortensis) essential oil (EO) and evaluating its herbicidal activity against Amaranthus retroflexus and Chenopodium album. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were employed to determine the chemical composition of the EO. Carvacrol (55.6%) and γ-terpinene (31.9%) were the major EO components. Low energy method was applied, allowing achievement of EO nanodroplets. The NE also presented low polydispersity, and the mean droplet was below 130nm even after storage for 30d. Laboratory tests showed that the NE at different concentrations (100, 200, 400, 800, and 1000μL.L−1) significantly (P≤0.05) reduced the germination indices and the seedling's growth in dose-response. The inhibitory effect was the greatest at 800μL.L−1 NE. Overall, root length was more inhibited as compared to shoot length. Post-emergence application of NE at different concentrations (1000, 2000, 3000, 4000 and 5000μL.L−1 of EO) on 2–4 true leaves' stage of the weeds caused significant (P≤0.05) decrease in the growth factors in dose-dependent manner. Complete lethality was observed by 4000μL.L−1 NE sprayed on the weeds. Spraying of NE significantly (P≤0.05) reduced chlorophyll content in the tested weeds. Increasing in relative electrolyte leakage (REL) 1 and 5d after treatment represented significant cell membrane disruption and increased cell membrane permeability. Transmission electron microscope (TEM) pictures confirmed NE droplet size and demonstrated membrane destruction. The study approved that the NE of S. hortensis EO has herbicidal properties as it has high phytotoxic effect, and interferes with the germination, growth and physiological processes of the weeds. The production of NE from S. hortensis EO is a low energy method that offers a promising practical natural herbicide for weed control in organic agricultural systems.

Effects of mechanical processing and annealing on optical coherence properties of [formula omitted]:LiNbO3 powders

Optical coherence lifetimes and decoherence processes in erbium-doped lithium niobate (Er3+:LiNbO3) crystalline powders are investigated for materials that underwent different mechanical and thermal treatments. Several complimentary methods are used to assess the coherence lifetimes for these highly scattering media. Direct intensity or heterodyne detection of two-pulse photon echo techniques was employed for samples with longer coherence lifetimes and larger signal strengths, while time-delayed optical free induction decays were found to work well for shorter coherence lifetimes and weaker signal strengths. Spectral hole burning techniques were also used to characterize samples with very rapid dephasing processes. The results on powders are compared to the properties of a bulk crystal, with observed differences explained by the random orientation of the particles in the powders combined with new decoherence mechanisms introduced by the powder fabrication. Modeling of the coherence decay shows that paramagnetic materials such as Er3+:LiNbO3 that have highly anisotropic interactions with an applied magnetic field can still exhibit long coherence lifetimes and relatively simple decay shapes even for a powder of randomly oriented particles. We find that coherence properties degrade rapidly from mechanical treatment when grinding powders from bulk samples, leading to the appearance of amorphous-like behavior and a broadening of up to three orders of magnitude for the homogeneous linewidth even when low-energy grinding methods are employed. Annealing at high temperatures can improve the properties in some samples, with homogeneous linewidths reduced to less than 10kHz, approaching the bulk crystal linewidth of 3kHz under the same experimental conditions.

New algal lipid extraction procedure using an amphiphilic amine solvent and ionic liquid

Lipid extraction is a key step in microalgal biofuel production. However, economical microalgal biofuel production is limited by the high energy consumption of the extraction process. Therefore, in this study, we employed N-methylcyclohexylamine (MCHA) as a switchable solvent to directly extract a wet microalgal slurry, and an ionic liquid, [C4-mim][PF6] (1-butyl-3-methylimidazolium hexafluorophosphate), was used to recover the extracted algal oil through a simple phase separation method. CO2 was used to trigger the separation of MCHA from [C4-mim][PF6], and MCHA was regenerated by heating and purging with N2. Our extraction procedure differs from conventional solvent extraction, which requires drying algal slurries before extraction. The new extraction procedure adopted in this study can be used to extract wet algal slurries directly and recycle the solvent by using a low-energy consumption method. In addition, water-soluble MCHA was investigated for DHA(docosahexaenoic acid) wet algal slurries with 85% water content, and the extraction yield could reach 85% at low stirring speeds (200 rpm). Using [C4-mim][PF6] to separate algal oil from the crude extraction liquid, algal lipid recovery was approximately 77%. In summary, the results showed the feasibility of utilizing MCHA and [C4-mim][PF6] as extracting and separating agents, respectively, for algal oil exaction.

Removal of ammonium from municipal wastewater with powdered and granulated metakaolin geopolymer

ABSTRACTAmmonium removal from municipal wastewater poses challenges with the commonly used biological processes. Especially at low wastewater temperatures, the process is frequently ineffective and difficult to control. One alternative is to use ion-exchange. In the present study, a novel ion-exchanger, metakaolin geopolymer (MK-GP), was prepared, characterised, and tested. Batch experiments with powdered MK-GP indicated that the maximum exchange capacities were 31.79, 28.77, and 17.75 mg/g in synthetic, screened, and pre-sedimented municipal wastewater, respectively, according to the Sips isotherm (R2 ≥ 0.91). Kinetics followed the pseudo-second-order rate equation in all cases (kp2 = 0.04–0.24 g mg−1 min−1, R2 ≥ 0.97) and the equilibrium was reached within 30–90 min. Granulated MK-GP proved to be suitable for a continuous column mode use. Granules were high-strength, porous at the surface and could be regenerated multiple times with NaCl/NaOH. A bench-scale pilot test further confirmed the feasibility of granulated MK-GP in practical conditions at a municipal wastewater treatment plant: consistently <4 mg/L could be reached even though wastewater had low temperature (approx. 10°C). The results indicate that powdered or granulated MK-GP might have practical potential for removal and possible recovery of from municipal wastewaters. The simple and low-energy preparation method for MK-GP further increases the significance of the results.

Utilization of dynamic light scattering to evaluate Pterodon emarginatus oleoresin-based nanoemulsion formation by non-heating and solvent-free method

Pterodon emarginatus Vogel, Fabaceae, is a great source of bioactive compounds. The most known and studied herbal derivative from this species is an ambar-colored oleoresin that contains vouacapane diterpenes and volatile terpenoids, such as β-caryophyllene. Some recent papers aimed to generate nanoemulsions using this oleoresin for biological applications. However, they used high-energy methods that elevate costs of the process or heating procedures, which offer the disadvantage of possible volatile substances loss. Thus, as part of our ongoing studies with nanobiotechnology of natural products, especially regarding preparation of nanoemulsions with promising plant-based oils by low cost and low energy methods, we decided to evaluate the ability of non-heating and solvent-free method to generate P. emarginatus oleoresin-based nanoemulsions. Two non-ionic surfactants were used to generate the nanoemulsions by a simple homogenization method with vortex stirrer. Low mean droplet size (<180nm) and low polydispersity index (<0.200) were observed even after one day of preparation. The low coefficient of variation for the analyzed parameters of different batches and similar profile for droplet size distribution suggested reproducibility of the method. After 30 days, some degree of droplet growth was observed on nanoemulsion prepared with polyethyleneglycol 400 monooleate, while almost no alteration was observed for nanoemulsion prepared with polysorbate 85. Programmed temperature ramp analysis revealed that no major effects on droplet size and polydispersity index were observed, suggesting the robustness of formed nanoemulsions. Thus, the present study shows for the first time the formation of sucupira-based nanoemulsions by a simple, low cost and ecofriendly method. This study opens new perspectives for bioactive evaluation of this novel nano-product.

Transition-metal-free direct perfluoroalkylation of quinoline amides at C5 position through radical cross-coupling under mild conditions

A simple low-energy and efficient method is established for the synthesis of C5-selective perfluoroalkylation quinolines in the absence of any transition metal catalysts.

A new method for the formulation of double nanoemulsions.

Double emulsions are very attractive systems for many reasons; the most important of these are their capacity to encapsulate hydrophilic and lipophilic molecules simultaneously in a single particle and their potentiality to protect fragile hydrophilic molecules from the continuous phase. Double emulsions represent a technology that is widely present down to the micrometer scale; however, double nanoemulsions, with their new potential applications as nanomedicines or diagnosis agents, currently present a significant challenge. In this study, we propose an original two-step approach for the fabrication of double nanoemulsions with a final size below 200 nm. The process consists of the formulation of a primary water-in-oil (w1/O) nanoemulsion by high-pressure homogenization, followed by the re-emulsification of this primary emulsion by a low-energy method to preserve the double nanostructure. Various characterization techniques were undertaken to confirm the double structure and to evaluate the encapsulation efficiency of a small hydrophilic probe in the inner aqueous droplets. Complementary fluorescence confocal and cryo-TEM microscopy experiments were conducted to characterize and confirm the double structure of the double nanoemulsion.

Sustainable Heating or Cooling and Ventilation of Affordable Zero-energy Housing

This paper updates the ongoing research, by simulation and experimentation for a sustainable low-energy method to heat or cool and ventilate affordable housing. Renewable sources are used to heat or cool water which is circulated to low temperature (22-25°C) radiators (LTRs) on inside faces to make houses as thermally comfortable as caves. In cool (15°C annual average temperature) Melbourne, Australia, water from 100m-deep VGHEs has been measured at 22-24°C. Using the 25-30°C increase in ground temperature per kilometre depth given by the International Panel on Climate Change, the depth should be about 200m. Most of the inhabited places have annual average temperature of more than 0°C, and the estimated depth would be less than 1 kilometre. Literature review is included in the introduction and discussion. Method for heating (experimental house/s in Melbourne, Australia) is grouped with simulated results and experimental findings. Next subsection presents experiments in hot tropical Kuching, Malaysia and simulated results. The heat extracted from VGHE in winter is sustainable because in summer, solar-heated water is used for replenishment. In summer and tropical climates, the fan, which can create a cooling sensation of up to 4°C can enable 30.5°C indoors comfortable. Low power is required to circulate water and operate fans and can come from photovoltaics on the roof, enabling off-grid or zero-energy houses. Plans for May-August 2018 experiments include the use of a 300W photovoltaic thermal (PV/T) i.e., outdoor air will be drawn through the gap between the metallic roof and insulated ceiling, to be preheated ventilation air in winter. In Kuching, Malaysia, the water is cooled by radiation to the night sky to 25°C. The cooling coil of a PV or PV/T powered chiller is proposed to make the water colder. Hotter days would likely have more solar radiation to generate more power for the photovoltaic to make the coil colder. The ground source heat pump is not used, thus the VGHE-LTR could be comparable in cost to conventional e.g., horizontal GHE with heat pumps and high temperature (about 50°C) radiators. LTRs could be integrated into the inside metal that clads structural insulated panels and housing would be affordably constructed. Funding is sought for an experimental house in cool/cold climates with LTRs heated by a 23°-bottom temperature VGHE.

Investigation of structural properties of electron-beam deposition of zinc oxide coatings doped with copper

A new method of vacuum formation of doped ZnO coatings is proposed. ZnO thin films doped with copper were coated in silicon substrate by low-energy electron beam deposition method. The authors investigated the effect of deposition parameters on the structural properties of the ZnO thin films. The orientation of the ZnO thin films were investigated by X-ray diffraction (XRD) patterns. The doping of zinc oxide coatings with copper led to a disorienting effect. It has been shown that copper has a nonmonotonic effect on the bandgap value, which is changing from 2.67 to 3.33eV. The increase in Eg is determined due to the changes in structure of ZnO matrix layer with low concentration of Cu, whereas with high concentration of copper, Eg decreases due to the presence of copper oxide as a separate phase. UV–Vis and IR spectra demonstrate the significant change in structure of ZnO in presence of Cu.

Deuterium supersaturation in low-energy plasma-loaded tungsten surfaces

Fundamental understanding of hydrogen–metal interactions is challenging due to a lack of knowledge on defect production and/or evolution upon hydrogen ingression, especially for metals undergoing hydrogen irradiation with ion energy below the displacement thresholds reported in literature. Here, applying a novel low-energy argon-sputter depth profiling method with significantly improved depth resolution for tungsten (W) surfaces exposed to deuterium (D) plasma at 300 K, we show the existence of a 10 nm thick D-supersaturated surface layer (DSSL) with an unexpectedly high D concentration of ~10 at.% after irradiation with ion energy of 215 eV. Electron back-scatter diffraction reveals that the W lattice within this DSSL is highly distorted, thus strongly blurring the Kikuchi pattern. We explain this strong damage by the synergistic interaction of energetic D ions and solute D atoms with the W lattice. Solute D atoms prevent the recombination of vacancies with interstitial W atoms, which are produced by collisions of energetic D ions with W lattice atoms (Frenkel pairs). This proposed damaging mechanism could also be active on other hydrogen-irradiated metal surfaces. The present work provides deep insight into hydrogen-induced lattice distortion at plasma–metal interfaces and sheds light on its modelling work.