Magnesium Zinc Research Articles

Enhancing oil recovery through nanofluids flooding with Irvingia gabonensis in the Niger Delta

Application of nanofluids flooding in the oil and gas industry is recently emerging as enhanced oil recovery methods. Nanoparticles have the ability to alter the rock formation in order to recover oil trapped in the pores of the rock to improve oil recovery. In this study, core plug samples were formulated in the laboratory to investigate the effect of nanoparticles on oil recovery. The formulated core samples were saturated in low salinity brine. However, low salinity brine was used because it has the ability to alter rock wettability. After core flooding with brine for secondary recovery process, extracted oil from Irvingia gabonensis was introduced into the formation to investigate the effect of Irvingia gabonensis on oil recovery. The result of the study showed that magnesium oxide, silicon oxide, aluminum oxide and zinc oxide had oil recovery of 38.1%, 45.6%, 47.7% and 35.1%, respectively. However, when the nanofluids with Irvingia gabonensis were injected into the formation as a displacing agent, the oil recovery greatly improved to 50.3%, 52.0%, 53.2% and 52.4% for (MgO, SiO2, Al2O3 and ZnO). The result of the study showed that nanofluid flooding is a promising potential to improve oil recovery in the Niger Delta.

Nanometer-Thick MgxZn(1–x)O Ternary Films for Photovoltaics

Owing to their tunable bandgap with the concentration of the Mg dopant, magnesium–zinc oxide (MgxZn(1–x)O) ternary nanometer-thick thin films have been widely studied for applications in the fields...

Biobutanol as a potential alternative to petroleum fuel: Sustainable bioprocess and cost analysis

Present study demonstrates a two-stage sequential bioprocess for production of biobutanol using low-cost substrates, corn steep liquor and industrial grade maize starch. Improved butanol titer using low-cost substrates was achieved via combinatorial approach of: (i) optimization of initial concentration of corn steep liquor and starch; (ii) hydrolysis of starch into fermentable sugar using industrial grade amylase and (iii) coupling attributes of butanol upregulation via magnesium starvation and zinc supplementation. The strategy resulted in a butanol titer of 16.54 g L−1 with a yield of 0.28 g g−1. Physicochemical properties of butanol-diesel blends e.g. kinematic viscosity, absolute viscosity, density, flash point, fire point, cloud point and pour point corroborate well with pure diesel. Engine performance analysis revealed enhanced brake thermal efficiency with negligible change in key engine performance parameters under butanol-diesel blends as compared to diesel, depicting suitability of butanol as potent liquid transportation fuel. The present bioprocess strategy using low-cost substrates resulted in a price of 0.8 USD for every litre of butanol, offering economic feasibility for possible commercial realization.

New Mg-Ca-Zn amorphous alloys: Biocompatibility, wettability and mechanical properties

Mg-Ca-Zn alloys are considered to be biodegradable materials and nontoxic to the living cell. Thus, they are promising candidates for use in orthopedic applications. In the present work, two new Mg-based glassy alloys (Mg72Ca12Zn16 and Mg63Ca15Zn22) are synthesized by melt spinning. The prospect of these alloys for biomedical application is assessed by evaluating and comparing their mechanical properties, biodegradation and biocompatibility with the well established glassy alloy composition, Mg60Ca5Zn35, synthesized under identical conditions. With decreasing Zn content in the composition, the density of the melt spun alloys decreases. The new alloys show lower hardness and an about ~35% lower Young's modulus than the Mg60Ca5Zn35 alloy. In vitro degradation behavior in Hank's balanced salt solution (HBSS) solution yields a higher degradation rate for the new alloys than for the existing Mg60Ca5Zn35 alloy. Degradation products are characterized using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), confirming the presence of magnesium hydroxide (Mg(OH)2), hydroxyapatite (HAp), and ternary calcium magnesium zinc (Ca2Mg6Zn3) phases. In vitro biocompatibility studies with a mouse osteoblast cell line (MC3T3-E1) clearly demonstrates the non-cytotoxic nature of the alloys. The results altogether suggest possible biomedical applications of the new Mg-based glassy alloys.

A lean magnesium–zinc–calcium alloy ZX00 used for bone fracture stabilization in a large growing-animal model

Over the last decade, demand has increased for developing new, alternative materials in pediatric trauma care to overcome the disadvantages associated with conventional implant materials. Magnesium (Mg)-based alloys seem to adequately fulfill the vision of a homogeneously resorbable, biocompatible, load-bearing and functionally supportive implant. The aim of the present study is to introduce the high-strength, lean alloy Mg‒0.45Zn‒0.45Ca, in wt% (ZX00), and for the first time investigate the clinical applicability of screw osteosynthesis using this alloy that contains no rare-earth elements. The alloy was applied in a growing sheep model with osteotomized bone (simulating a fracture) and compared to a non-osteotomy control group regarding degradation behavior and fracture healing. The alloy exhibits an ultimate tensile strength of 285.7 ± 3.1 MPa, an elongation at fracture of 18.2 ± 2.1%, and a reduced in vitro degradation rate compared to alloys containing higher amounts of Zn. In vivo, no significant difference between the osteotomized bone and the control group was found regarding the change in screw volume over implantation time. Therefore, it can be concluded that the fracture healing process, including its effects on the surrounding area, has no significant influence on degradation behavior. There was also no negative influence from hydrogen-gas formation on fracture healing. Despite the proximal and distal screws showing chronologically different gas release, the osteotomy showed complete consolidation. Statement of SignificanceConventional implants involve several disadvantages in pediatric trauma care. Magnesium-based alloys seem to overcome these issues as discussed in the recent literature. This study evaluates the clinical applicability of high-strength lean Mg‒0.45Zn‒0.45Ca (ZX00) screws in a growing-sheep model. Two groups, one including a simulated fracture and one group without fracture, underwent implantation of the alloy and were compared to each other. No significant difference regarding screw volume was observed between the groups. There was no negative influence of hydrogen-gas formation on fracture healing and a complete fracture consolidation was found after 12 weeks for all animals investigated.

Associations of Bariatric Interventions With Micronutrient and Endocrine Disturbances

Few studies have described the longitudinal trajectories of serum levels of micronutrients whose deficiencies are associated with serious sequelae following bariatric procedures, such as anemia, osteoporotic fractures, and neuropathies. Furthermore, previous studies comparing laparoscopic sleeve gastrectomy (LSG) vs Roux-en-Y gastric bypass (LRYGB) or one-anastomosis gastric bypass (OAGB) procedures may have been limited by selection and confounding biases. To appraise the spectrum and temporal course of micronutrient deficiencies associated with bone metabolism and erythropoiesis after LSG vs OAGB or LRYGB procedures, using the propensity score as a balancing score. This prospective, longitudinal comparative effectiveness study was conducted at a high-volume bariatric unit in Singapore from September 1, 2008, to November 30, 2017, with a cutoff date for analysis of September 2018. Patients who underwent adjustable gastric banding, biliopancreatic diversion procedures, and intragastric balloon procedures were excluded. All other patients who underwent bariatric procedures were included. Data were analyzed from September 23 to 30, 2018. Serial assessment of 13 biochemical parameters at 12 time points for up to 5 years after bariatric procedure. Inverse probability-of-treatment weights were used to obtain estimates of the mean associations of variables assessed with the bariatric surgical interventions. Longitudinal trajectories were analyzed using mixed-effects generalized linear models to apportion the temporal variation of serum micronutrients into fixed-effects and random-effects components. A total of 688 patients were included in this study, of whom 499 underwent LSG (mean [SD] age, 41.5 [11.3] years; 318 [63.7%] women) and 189 underwent OAGB or LRYGB (mean [SD] age, 48.6 [9.4] years; 112 [59.3%] women). There were no differences during follow-up among patients who underwent LSG vs those who underwent OAGB or LRYGB in intact parathyroid hormone levels (mean difference, 7.05 [95% CI, -28.67 to 42.77] pg/mL; P = .70), serum 25-hydroxyvitamin D levels (mean difference, -0.72 [95% CI, -1.56 to 0.12] ng/mL; P = .09), or phosphate levels (mean difference, 0.006 [95% CI, -0.052 to 0.064] mg/dL; P = .83). Hemoglobin levels were a mean 0.63 (95% CI, 0.41 to 0.85) g/dL higher among patients who underwent LSG compared with those who underwent OAGB or LRYGB (P < .001), despite no differences in iron concentration levels (mean difference, 1.50 [95% CI, -1.39 to 4.39] µg/dL; P = .31), total iron-binding capacity (mean difference, 4.36 [95% CI, -5.25 to 13.98] µg/dL; P = .37), or ferritin levels (mean difference, 3.0 [95% CI, -13.0 to 18.9] ng/mL; P = .71). Compared with patients who underwent LSG procedures, patients who underwent OAGB or LRYGB had higher folate levels (mean difference, 2.376 [95% CI, 1.716 to 3.036] ng/mL; P < .001) but lower serum magnesium levels (mean difference, -0.25 [95% CI, -0.35 to -0.16] mg/dL; P < .001) and zinc levels (mean difference, -7.58 [95% CI, -9.92 to -5.24] µg/dL; P < .001). These findings suggest that LSG vs OAGB or LRYGB procedures have differential associations with various micronutrient and metabolic parameters. These differences should be recognized in guidelines for postbariatric nutritional surveillance and prevention.

The Magneto-mechanical Properties of Cobalt Substituted Mg-Zn Nanoferrites

Despite increasing solicitude in magnesium-zinc ferrites as advanced ceramics, there is still much uncertainty regarding their mechanical and magnetic properties. Precursors Co2+ ions substituted magnesium zinc spinel ferrites with chemical formula Mg0.8Zn0.2-xCoxFe2O4; (0 ≤ x ≤ 0.2) (MZCFO) were scrutinized. XRD patterns confirmed the formation of the spinel structure for all MZCFO nanoferrites with no traces of any secondary phases. An excellent correlation is between the structural, mechanical, and magnetic theoretical and experimental results; supporting the validity of cation distribution. The experimental lattice parameter of MZCFO is found in the range 8.3893–8.3803 A, and the theoretical one is found in the range 8.3882–8.3833 A. The average crystallite size is calculated using the two methods (Debye–Scherrer and Williamson–Hall), which was found in the range ~15–50 nm, to confirm the nanocrystalline nature of all MZCFO ferrites. The FE-SEM micrographs illustrate the nanoferrite morphology exhibiting rocky-shaped particles with variable pore size. The HR-TEM micrographs of the as-prepared nanoferrites reveal agglomerated round-shaped nanoferrite particles. EDX spectra reveal the presence of all chemical elements, and SAED micrographs confirm the polycrystalline nanosized nature of MZCFO samples. Also, FTIR analysis affirmed the spinel structure by exhibiting the distinctive vibrational band of the ferrite bonds. Experimental and theoretical elastic moduli (bulk (B), rigidity (G), Young (E)) besides Poisson ratio (σ) and Debye temperature (ϴD) of MZCFO nanoferrites were investigated. The bond length is the main reason for the insignificant variation in the elastic moduli of MZCFO with further cobalt substitution. Cation distribution is the main reason for the nanoferrite Mg0.8Zn0.12Co0.08Fe2O4 (x = 0.08) to have the highest MS value (40 emu/g) and the exceptional level of flexibility obtained for the mechanical properties. The coercivity exhibits an increasing demeanor with Co2+ substitution (HC = 569.35 at x = 0.2), which is correlated to the strong magnetic anisotropy property of Co2+ species in B sites. These advantages can initiate a considerable attention in implementing this ferrite in applications such as high-density magnetic recording, loudspeakers, and sensors.

Improving optical properties and controlling defect-bound states in ZnMgO thin films through ultraviolet–ozone annealing

Bandgap-engineered oxide semiconductors have received widespread research attention in such applications as sensors, photodetectors, electronic devices, and solar cells. Zinc magnesium oxide (ZnMgO) is important in optoelectronics because of its wide bandgap and high excitonic binding energy. A primary drawback of ZnMgO thin films has been the presence of inherent point defects, which limits their applicability in optoelectronics devices; nevertheless, these defects can be overcome through post-growth annealing. However, annealing temperatures are typically high, in the range of 700-1000°C, which is unfit for integration in upcoming flexible electronic device applications. Herein, we propose an ultraviolet-ozone (UVO) annealing technique to improve the quality of thin films; the proposed approach is a low-temperature, simple, and cost-effective process. We studied the effects of postgrowth UVO annealing time (10, 30, 70, and 90 min) on radio frequency sputtered ZnMgO thin films. The films were then characterized through optical, structural, and elemental characterization techniques. Post-UVO annealing considerably improved near band emissions and suppressed defect bound emission. Room-temperature photoluminescence measurements revealed a 104 improvement in the near band emission peak of the 70 min UVO treated film compared with the as-deposited film. The ratio of the peak intensities of near band emission and defects band emission for the 70-min post-UVO film was 50 × higher than that of the as-deposited film. High-resolution X-ray photoelectron spectroscopy evidenced the suppression of oxygen vacancies and strengthening of the metal–oxygen bonds in the ZnMgO lattice of the 70-min post-UVO annealed film. Scanning electron microscopy images demonstrated improvements in the morphological properties of the post-UVO films.

Comparison of corrosion resistance and biocompatibility of magnesium phosphate (MgP), zinc phosphate (ZnP) and calcium phosphate (CaP) conversion coatings on Mg alloy

Seven different conversion coatings (which can be classified into three types: MgP, ZnP and CaP) were prepared on Mg alloy substrates to compare the corrosion resistance and biocompatibility of these coatings. Biocompatibility and cytotoxicity of different coated samples and bare Mg alloy were studied using the CCK-8 test. The corrosion resistance of different conversion coatings was comparatively studied by electrochemical tests (OCP, EIS and PDP) and long-term immersion test in Hanks' solution. Based on the experimental results, the corrosion mechanism of different types of conversion coatings and Mg alloy substrate was proposed and investigated.

Investigation the influence of Zn2+ doping on the photovoltaic properties (DSSCs) of MgO nanoparticles

The present work demonstrates the synthesis of MgO and ZnO–MgO nanospheres with various concentration (2, 4, 6, 8 and 10 wt%) of Zn2+ through microwave combustion route using magnesium nitrate and zinc nitrate as precursors and ethylene glycol as solvent. The effect of doping was studied through powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive analysis using X-rays (EDAX), transmission electron microscopy (TEM) and photoconductivity (I–V) technique. Tryptan Blue, SPADNS and Evans Blue dyes were used for the first time as a photosensitizer on ZnO–MgO nanoparticles. Optical and electrochemical characteristics of dyes revealed that the optical bandgap, HOMO and LUMO levels of dyes are well matched with conduction band of ZnO–MgO nanoparticles. I–V characteristics of ZnO–MgO films before and after sensitisation with dyes revealed the influence of dye sensitisation on photo conductivity of ZnO–MgO nanoparticles. In addition, the better adsorption of Trypan Blue (TB), SPADNS (SPD) and Evans Blue (EB) dyes on ZnO–MgO film is due to porous nature of ZnO–MgO. This gives more transportation of electron from dye to ZnO–MgO which enhances the power conversion efficiency of solar cell.

Zinc Magnesium Oxide-Based Nanorods for High-Precision pH Sensing

We developed a zinc magnesium oxide–based nanosensor platform for pH sensing. pH is a parameter strongly influential in various chemical, biological, and biomedical applications. Oxide-based semiconductors are preferred as pH sensing materials because of their robustness, size modulation, high sensitivity, cost effectiveness, reversibility of the sensing process, and long lifetime. Vertical nanorods of zinc magnesium oxide were fabricated for the nanosensor platform. Their high crystalline quality was confirmed through various structural characterization techniques such as high-resolution X-ray diffraction and scanning and transmission electron microscopy. Absorption spectroscopy revealed a bandgap of 3.56 eV corresponding to 12% magnesium. pH dependent photoluminescence (PL) measurements showed a shift in the visible range spectrum with decrease in PL intensity. The developed sensor showed high sensitivity of 44.4 ± 3.8 mV/pH, close to the theoretical value, in the 2.4–10 pH range. AC- and DC-based current measurements were performed to study the sensing mechanism. Conductance-based pH measurement, a unique and precise technique, yielded a high sensitivity of 4.59 mS/pH. The proposed nanosensors, which are low cost and easy to fabricate and use, exhibited rapid response, long-term stability, high sensitivity (in both potentiometric as well as conductance-based measurements), and high repeatability.

Heat Conduction of Ceramic Materials Based on MgAl2O4 and ZnAl2O4

Optically transparent samples of ceramic materials based on the magnesium aluminate and zinc aluminate spinels of density close to the theoretically attainable one have been obtained, and their heat conductivity was measured in the temperature range 50–300 K. It is shown that the heat conductivities of these ceramic materials at room temperature are close and fall within the range 17–18 W/(m·K). At a cryogenic temperature (T = 50 K), the heat conductivity of the ceramic materials based on the zinc aluminate spinel (180 W/(m·K)) is much higher than the heat conductivity of the ceramic materials based on the magnesium aluminate spinel (122 W/(m·K)). The absolute heat conductivities of the ceramic materials based on the indicated spinels are dependent on the sintering additives used in their production.

Effect of Natural Fermentation on Antioxidant Activity of Pearl Millet (Pennisetum glaucum)

Background: Millets are small-seeded cereals having excellent nutritional quality. They are comparable or superior to some commonly consumed cereals like wheat and rice. Millets are gluten-free, have low Glycemic Index and are a good source of calcium, iron, potassium, zinc magnesium and B vitamins. Natural fermentation of millets can improve their lower cooking quality, taste, low bioavailability and palatability. Objective: This study was undertaken to evaluate the effect of natural fermentation on antioxidant activity of Pearl millet (Pennisetum glaucum). Methods: The present work has been done to standardize the natural fermentation process of pearl millet using response surface methodology for enhanced iron content and antioxidant activity. Pearl millet was treated with natural fermentation process at varying temperature (30-50°C), time (4-12 hrs) and pH (3-7). The effect of these fermentation treatments were studied on total reducing sugar, iron content, antioxidant activity (Total Phenolic content and DPPH), tannin content and antinutritional factors of pearl millet using a second order central composite design. Results: The cofficient of determination, R2 values for Total reducing sugar, iron content, antioxidant activity and tannin content was greater than 0.900. Statistical analysis showed that sugar, iron content, antioxidant activity and tannin content varied significantly (p &lt;0.05) with a change in pH, temperature and time. pH was found to be the most important factor affecting the quality parameters of the pearl millet during fermentation as it exerted a strong influence (p &lt; 0.01) on all the dependent variables. Conclusion: Increase in total reducing sugar, iron content, antioxidant activity and decrease in tannin content of pearl millet were observed along with a decrease in pH and temperature of fermentation. On the basis of response surface and contour plots, the fermentation conditions of pearl millet were optimized at a temperature of 40°C, pH 5 and time duration of 8 hours.

CuSCN as the Back Contact for Efficient ZMO/CdTe Solar Cells.

The replacement of traditional CdS with zinc magnesium oxide (ZMO) has been demonstrated as being helpful to boost power conversion efficiency of cadmium telluride (CdTe) solar cells to over 18%, due to the reduced interface recombination and parasitic light absorption by the buffer layer. However, due to the atmosphere sensitivity of ZMO film, the post treatments of ZMO/CdTe stacks, including CdCl2 treatment, back contact deposition, etc., which are critical for high-performance CdTe solar cells became crucial challenges. To realize the full potential of the ZMO buffer layer, plenty of investigations need to be accomplished. Here, copper thiocyanate (CuSCN) is demonstrated to be a suitable back-contact material with multi-advantages for ZMO/CdTe solar cells. Particularly, ammonium hydroxide as the solvent for CuSCN deposition shows no detrimental impact on the ZMO layer during the post heat treatment. The post annealing temperature as well as the thickness of CuSCN films are investigated. Finally, a champion power conversion efficiency of 16.7% is achieved with an open-circuit voltage of 0.857 V, a short-circuit current density of 26.2 mA/cm2, and a fill factor of 74.0%.

Europium Doped Magnesium Zinc Sulfophosphate Glass as Potential Red Laser Host

Demand for rare earth ions (REIs) doped inorganic glasses have been ever-increasing for diverse photonic applications. Synthesis of these glasses needs the appropriate choice of suitable host matrices, modifiers, and REIs as dopants to improve their spectroscopic traits. In this realization, a new series of magnesium-zinc-sulfophosphate glasses were prepared with varied europium ions (Eu3+) doping contents (0 to 2.0 mol%). Such melt-quench synthesized glasses were characterized at room temperature by diverse analytical techniques to determine their physical and optical properties. XRD pattern of as-quenched samples confirmed their amorphous nature. Densities of the glass system were observed to increase from 2.540 to 2.788 g.cm−3 with the increase in Eu3+ doping contents from 0 to 2.0 mol% which were attributed to the generation of more bridging oxygen atoms and enhanced network compactness. Photoluminescence (PL) emission spectra of glasses exhibited four characteristic peaks positioned at 593, 613, 654 and 701 nm assigned to corresponding 5D0→7F0, 5D0→7F2, 5D0→7F3, and 5D0→7F4 transitions in Eu3+, in which the intensity of the peak at 613 nm (red) was highest. Emission intensities of all peaks were enhanced with the rise in Eu3+ content up to 1.5 mol% and quenched thereafter. It was affirmed that the physical and optical traits of these glass compositions can be improved by adjusting the Eu3+ doping contents. The proposed glass compositions may be potential for the development of varied photonic devices especially for eye safe solid-state red laser and fibre sensors.

Stable magnesium zinc oxide by reactive Co-Sputtering for CdTe-based solar cells

Magnesium zinc oxide (MZO) is a promising front contact material for CdTe solar cells. Due to its higher band gap than traditional CdS, MZO can reduce parasitic absorption to significantly increase short-circuit current density while also providing a benefit of conduction band offset tuning through Mg:Zn ratio optimization. MZO has been successfully implemented into CdTe devices, however its stability has been of concern. The MZO stability issue has been attributed to the presence of oxygen in the CdTe device processing ambient, leading to double-diode behavior (S-kink) in the current density-voltage curves. Here we report on MZO thin films deposited by reactive co-sputtering. The reactively co-sputtered MZO thin films have encouraging stability, show no significant variation in work function of the surface over a period of 6 months, as measured by Kelvin probe. Energy conversion efficiencies of around 16% have been achieved both with and without presence of oxygen in device processing ambients across multiple research facilities. These efficiencies should be possible to increase further by tuning of the thin film deposition and device processing parameters, especially through optimization of the back contact.

DFT Study of Structural and Electronic Properties of MgZnO Alloy

Structural and electronic properties of magnesium zinc oxide alloy with different Mg content and different configurations are studied by density functional theory. The energy track of rocksalt and wurtzite phases of MgZnO with different Mg content indicates that below 63% the wurtzite phase is energetically stable and above 63% the rocksalt phase is stable. Distribution of Mg in the MgZnO alloy is important to understand the phase segregation. By analyzing the distribution of Mg in the MgZnO alloy, we find that the energy required for two Mg to stay together is slightly larger than that for two Mg to stay apart, meaning that Mg has the potential to be uniformly distributed in the MgZnO alloy. By comparing with other dopants, we find that Mg introduces smaller lattice distortion. The corresponding electronic properties are studied by analyses of the density of state and the band structure. From the decomposed-projected band structure, we find that the energy level of O 2p orbitals is modulated to lower energy by introducing Mg, indicating that the enlargement of the band gap is partly caused by the subsidence of the valence band. For comparison, Cd modulates O 2p orbitals to a higher energy level, consistent with the presence of a narrow band gap.

Influence of unwoven roving and woven fabric carbon fiber reinforcements on reaction‐to‐fire properties of polymer matrix composites

SummaryThe influence of carbon fiber orientation on reaction‐to‐fire characteristics of layered polymer matrix composites is investigated in detail. M18‐1/G939 as woven fabric and M18‐1/G947 as unwoven roving prepregs with identical, epoxy based matrix composition were laid‐up to give 1 to 8 mm thick unidirectional and quasi‐isotropic laminates. Fundamental reaction‐to‐fire properties of these composites are interpreted on basis of the matrix components: epoxy resin and polyetherimide, as well as contained flame retardants magnesium hydroxide and zinc borate. Cone calorimetry and temperature distributions through the laminate show, that the velocity of combustion is influenced by fiber orientation for a given resin. For an unwoven roving it is confirmed that a quasi‐isotropic fiber orientation leads to faster ignition, due to preferred delaminations, but retards burning processes more effectively than a unidirectional lay‐up. This fundamental principle is extended to woven fabric reinforcements, however with less pronounced effects. Migration velocities of the pyrolysis zone are measured and additionally, decomposition of carbon fibers is considered. A comparison with a similar epoxy based matrix system without toughener and flame retardants: RTM6/G939 is carried out, in order to assess the effects by fiber orientation.

Phonon-Polariton Excitations in MgZnO/6H-SiC Structures

Specular infrared reflection spectra in the range of “residual rays” of the film and the substrate and in the case of the E⊥c orientation of the electric field have been simulated for the first time for thin MgxZn1−xO films deposited on optically anisotropic 6H-SiC substrates. The simulation was carried out making use of self-consistent parameters obtained earlier for magnesium oxide, zinc oxide, and silicon carbide single crystals. The film thickness and the Mg content x in the film are demonstrated to considerably distort the reflection spectra and to change the reflectivity of the MgxZn1−xO/6H-SiC structure. Using the Kramers–Kronig relation, the spectral intervals, where the reflectivity is sensitive to the film thickness and to the doping levels of the film and the substrate, are determined. The main attention is paid to analyze results obtained for x = 0.2. The existence of surface polaritons in such structures is theoretically demonstrated for the first time, and the attenuated total reflectance surface I(v)/I0(v) is plotted as a three-dimensional representation of the structure transmittance dependence on the radiation frequency and the incidence angle. A possibility to study the resonant interaction of optical phonons with plasmons in the film and the substrate is demonstrated.

Development of bioabsorbable zinc-magnesium alloy wire and validation of its application to urinary tract surgeries.

Metallic medical devices are typically constructed from non-bioabsorbable metals that remains in the body and causes considerable complications. Particularly in the urinary tract, calculus, intractable infection, and misdiagnosis as calculus are often caused by non-bioabsorbable metals. Here, we developed a zinc-magnesium alloy as a new bioabsorbable metal and sought to evaluate the bioabsorbable behavior of zinc and zinc-magnesium alloy in a rat bladder implantation model. We prepared zinc-magnesium alloy wires with various proportions of magnesium and investigated the strength, shape retention, formability, and absorbability of these novel materials. Then, we implanted zinc and zinc-magnesium alloy rings formed by the wires into rat bladder. Rats were euthanized at the end of the observation period, and the rings were removed for volume evaluation. Extracted bladder tissues were subjected to histological analysis. The strength of the zinc wire was enhanced by more than fourfold upon the addition of magnesium, without loss of ductility. Linear reduction of ring volume in urine was observed based on the concentration of magnesium within the ring. Nearly all rings were covered with a thin layer of calculus. Histological findings of the transected urinary bladder tissues did not differ among groups. Zinc-magnesium alloy is a promising candidate for use as a bioabsorbable medical device in the urinary tract.