Aluminum Absorption Research Articles

Experimental study of a parabolic trough solar collector with flat bar-and-plate absorber during direct steam generation

The present work aims at investigating an innovative flat aluminum absorber for process heat and direct steam generation in small linear solar concentrating collectors. After defining its optimal width through a Monte Carlo ray-tracing analysis, this absorber has been manufactured with the bar-and-plate technology, including an internal offset strip turbulator in the channel. This technology is cost-effective and extremely flexible, allowing to easily adapt the geometry of the absorber to different reflecting optics configurations. It has been mounted on an asymmetrical parabolic trough concentrator to form a solar collector with a concentration ratio of 42, which has been experimentally investigated. In particular, a new test procedure is presented, applied and validated to characterize the thermal performance of the collector during steam generation. The results show that a promising overall thermal efficiency of 64% at 0.160 K m2 W−1 can be achieved with negligible pressure drop.

Thermal absorber material selection for solar thermal Bi‐Metallic multilayer crosses absorber

The energy gain term determines the level of energy received by the solar absorber from solar radiation and various methods have been implemented to increase the collector performance using a bi-metallic cross absorber. Experiments have been conducted to determine suitable material pairing between the bi-metallic cross absorber and black coated flat-plate absorber. Five types of solar thermal absorbers are investigated under condition 525 W/m2 of solar radiation and with 0.52 m/s air flow speed in terms of heating and cooling performance. Four set stainless steel cross absorbers achieved best energy retention capability by obtaining the slope value of -0.1520 during the cooling phase while during the heating phase, coated flat plate performed well with a slope value of 0.4909. The profile of the thermal absorber with thermal absorption and thermal buffer can be summarized using a spider chart with distance index bar-chart, and the result shows that a bi-metallic, aluminium and stainless steel cross absorber exhibit the optimal balanced thermal profile. With the implementation of the material selection method could minimize the material selection process for cross absorber application.

EXPERIMENTAL AND MATHEMATICAL MODELING OF HALF-VALUE LAYER MEASUREMENTS FOR X-RAY EQUIPMENT

A linear mathematical modeling of half-value layer measurements for X-ray equipment is discussed. The consistency check shows that a linear model is consistent with the value of an exponential model, provided that the thickness of the aluminum absorber used in the calculations is close to 2.5[Formula: see text]mm. To validate the linear model, a methodology for determining the half-value layer in conventional X-ray equipment was introduced. The study was based on the measurement of only two exposure values, with and without aluminum absorber, using lithium fluoride thermoluminescent dosimeters (TLD-100). The corresponding description through a straight line is given. Aluminum absorber of 2.40[Formula: see text]mm thickness was used in the measurements in 11 X-ray equipment. A Pearson statistical analysis used to determine the correlation between data obtained with an ionization chamber and TLD-100 provided a statistically significant [Formula: see text] and p-value [Formula: see text] 0.004.

Analysis of Aluminium in Rat Following Administration of Allergen Immunotherapy Using Either Aluminium or Microcrystalline-Tyrosine-Based Adjuvants

Investigation into the absorption, distribution and elimination of aluminium in rat after subcutaneous aluminium adjuvant formulation administration using ICP-MS is described. Assays were verified under the principles of a tiered approach. There was no evidence of systemic exposure of aluminium, in brain or in kidney. Extensive and persistent retention of aluminium at the dose site was observed for at least 180 days after administration. This is the first published work that has quantified aluminium adjuvant retention based on the quantity of aluminium delivered in a typical allergy immunotherapy course. The results indicate that the repeated administration of aluminium-containing adjuvants will likely contribute directly and significantly to an individual's body burden of aluminium.

An experimental study on the thermal performance of a solar chimney with different dimensional parameters

For optimizing solar chimney power plant (SCPP) and also reaching to new experimental data, a pilot setup consisting of a chimney with 3 m height and 3 m collector diameter was constructed. Two main effective parameters including absorber material and geometric dimensions were analyzed using thermal and velocity data. In this paper, the main purpose is obtaining new experimental data in these new dimensions. The obtained data will be utilized in our future after studies for achieving a structural dimensional formulation of SCPPs. In fact, there is no comprehensive formula for achieving a precise relationship between the geometric parameters of the SCPPs. The dimension analyses show that the collector entrance distance of 6 cm has the best performance and the corresponding amounts of the chimney diameter and the chimney height are 10 cm and 3 m, respectively. Also, aluminum absorber has more heat transfer rate than iron one and the maximum fluid temperature difference between the collector and the ambient is 27 °C. The maximum air velocity of 1.7 m/s was recorded inside the chimney. In comparison to the chimney with 2 m height, this was about 55.3% higher.

Analysis of electronic autoradiographs by mathematical post-processing

ABSTRACTAutoradiography is a well-established method of nuclear imaging. When different radionuclides are present simultaneously, additional processing is needed to distinguish distributions of radionuclides. In this work, a method is presented where aluminium absorbers of different thickness are used to produce images with different cut-off energies. By subtracting images pixel-by-pixel one can generate images representing certain ranges of β-particle energies. The method is applied to the measurement of irradiated reactor graphite samples containing several radionuclides to determine the spatial distribution of these radionuclides within pre-defined energy windows. The process was repeated under fixed parameters after thermal treatment of the samples. The greyscale images of the distribution after treatment were subtracted from the corresponding pre-treatment images. Significant changes in the intensity and distribution of radionuclides could be observed in some samples. Due to the thermal treatment parameters the most significant differences were observed in the 3H and 14C inventory and distribution.

Experimental Investigation of Various Type Absorber Plates for Solar

In this study, four different types’ absorber plates were designed and compared of their energetic performances. These absorber plates were formed as a flat plate (Type I), V-shaped (Type II), wedge-shaped (Type III) and wavy-shaped (Type IV). Each type absorber plate was manufactured in both aluminum (Al) and copper (Cu) materials. Energy efficiencies of the heaters were investigated with airflow velocities of 2, 3 and 4 m s-1 experimentally and compared with each other. The results showed that efficiency of the heater with the copper absorber plate better than aluminum plate however, the resulting air temperature from heater with aluminum absorber plate higher than cooper plate. The experimental results have shown that Type IV and Type II achieved the highest energy efficiency, respectively.

Lactobacillus plantarum CCFM639 alleviates aluminium toxicity.

Aluminium (Al) is the most abundant metal in the earth's crust. Al exposure can cause a variety of adverse physiological effects in humans and animals. Our aim was to demonstrate that specific probiotic bacteria can play a special physiologically functional role in protection against Al toxicity in mice. Thirty strains of lactic acid bacteria (LAB) were tested for their aluminium-binding ability, aluminium tolerance, their antioxidative capacity, and their ability to survive the exposure to artificial gastrointestinal (GI) juices. Lactobacillus plantarum CCFM639 was selected for animal experiments because of its excellent performance in vitro. Forty mice were divided into four groups: control, Al only, Al plus CCFM639, and Al plus deferiprone (DFP). CCFM639 was administered at 10(9) CFU once daily for 10 days, followed by a single oral dose of aluminium chloride hexahydrate at 5.14 mg aluminium (LD50) for each mouse. The results showed that CCFM639 treatment led to a significant reduction in the mortality rates with corresponding decrease in intestinal aluminium absorption and in accumulation of aluminium in the tissues and amelioration of hepatic histopathological damage. This probiotic treatment also resulted in alleviation of hepatic, renal, and cerebral oxidative stress. The treatment of L. plantarum CCFM639 has potential as a therapeutic dietary strategy against acute aluminium toxicity.

Localized absorption in aluminum mask in visible spectrum due to longitudinal modes in vertical silicon nanowire arrays

Localized optical absorption in aluminum masks used for vertical silicon nanowire fabrication is demonstrated experimentally and supported using computer simulations. The mask is in the form of 30 nm thick aluminum nano-disks on top of silicon nanowires arranged in square lattices. The nanowires are 1 μm long, with diameters ranging from 60 nm to 100 nm and spaced 400 nm apart. New spectral features appear in the 500 nm–700 nm wavelengths range and are dependent on both the nanowire diameter and length. The former is due to the excitation of radial modes, whereas the latter stems from longitudinal (Fabry–Perot) resonances. The salient features associated with absorption in the aluminum mask and the role nanowire plays in this connection are discussed.

Regarding mini-review on bicarbonate therapy for prevention of chronic kidney disease progression

To the Editor: The mini-review on bicarbonate therapy for prevention of chronic kidney disease progression1 was a much-needed, well-written, and informative review. It has long been known that chronic acidosis seen in chronic kidney disease (CKD) 4 and 5 has a deleterious effect on digestion and general nutrition. The recommendation of rigorous treatment to prevent progression of CKD was well explained by various recently reported pathophysiological mechanisms that support the urgency of treatment. However, there was a recommendation in the management that is a cause of concern. Because of the probability of poor compliance and intolerance with administration of NaHCO3 compounds, the authors recommend other alkali products—e.g., Shohl’s solution (sodium citrate and citric acid) or polycitra (citric acid, potassium citrate, and sodium citrate)—as alternatives. They do issue a warning of the dangers of increased aluminum (Al) absorption in patients taking Al-containing phosphate binders but did not elaborate on this point. We showed that ingestion of a low dose of citrate contained in a well-known effervescent calcium supplement taken by normal volunteers as well as subjects with stable chronic renal failure resulted in an increase in the excretion of urinary Al in normal individuals and an increase in both serum and urine Al in those with CKD.2 The experiments showing this were accompanied by a low dose of Al hydroxide supplementation. The point of the research, however, was to alert medical practitioners that, even without Al supplementation, patients with CKD 3b, 4, and 5 may experience an increase in serum and urine Al if receiving compounds containing citrate. This is because all foodstuffs in a powdery form contain Al to prevent them from congealing, as AL has hydrophobic properties. For this reason we believe that all citrate-containing preparations are totally contraindicated because of the Al contained in, e.g., flour, custard powder, salt, sugar, etc. Although the bicarbonate powder may occasionally be unpleasant to take, it is safe and inexpensive, and the unpleasant taste can be disguised.

Triple-layer Fabry–Perot/SPP aluminum absorber in the visible and near-infrared region

We report a theoretical study on a novel type of absorber that can achieve near perfect absorption in the visible and near-infrared regions by utilizing the Fabry-Perot and the surface plasmon polariton (SPP) effects. The absorber consists of an Al/dielectric/Al triple-layered structure with the top Al layer consisting of an array of holes. The absorption features can be easily controlled by tuning the structural parameters, particularly the porous features of the top Al layer. When the porous features in the top Al layer are significantly smaller than the wavelength, light absorption is enabled through the Fabry-Perot effect. On the other hand, when the porous features in the top layer are at the subwavelength scale, new absorption peaks emerge due to the SPP effect. Furthermore, when the top Al layer consists of an array of hollow rings, the electric field at the interface between the top Al layer and the middle dielectric layer is greatly enhanced due to the plasmonic effect, indicating that the absorber reported here may be suitable for novel applications, e.g., the surface-enhanced Raman spectroscopy (SERS) substrates.

Comparisons and analyses of the aluminum K-shell spectroscopic models

Comparing different collisional-radiative models is of great importance for validating the models for plasma spectroscopy and improving the diagnostic accuracy of plasma parameters. In this paper, the widely applied K-shell spectroscopic models, FAC and FLYCHK, are compared based on their calculation results of the aluminum K-shell emissivity and absorption coefficient. The state abundances, K-shell line ratios, K-shell emissivities and absorption coefficients in a wide range of plasma temperatures and densities are calculated and compared, and the reasons for the differences between these two models are discussed. In an electron temperature range from 200 to 800 eV, and an electron density range from 1017 to 1024 cm-3, the Al ions in the plasma are mainly composed of H-like and He-like ions. The ground-state populations of the H-like and He-like ions, calculated from FAC model, are in good agreement with the results from FLYCHK. Number densities of the excited states are two orders or more less than those of the ground states from both the models, and significant differences are observed in the number densities of n=2 and n=3 states of both the H-like and He-like ions. These differences will further result in the differences in spectral line emissivity and their line emissivity ratio, such as He-IC/He-αup and H-βup/He-βup, which are key parameters used to diagnose the electron temperature and density. The line emissivity ratio Ly-αup/(He-αup+He-IC) is less dependent on the electron density, and the difference in line emissivity ratio between the two models mainly lies in the parameter region where both the electron temperature and density are high. The ratio He-IC/He-αup is less dependent on the electron temperature when the electron density is more than 1019 cm-3 while significant differences are observed at a lower electron density.#br#The reason for the difference between the number densities of the low-energy excited states from FAC and FLYCHK models is analyzed by comparing the rate coefficients of various collisional and radiative processes in the rate equation of each state. The differences in the n=2 excited states of H-like ions come from the fact that FAC and FLYCHK models use the detailed-level model and the super-configuration model respectively to construct the rate equations of these states. The FAC model ignores the collisional excitation and de-excitation processes between the n=3 state and higher excitation states (e.g. n = 4) in H-like and He-like ions, which are responsible for the density difference in the n=3 excited state. Higher Rydberg states considered in FLYCHK model do not have any significant influence on the density of the ground-states. The difference in the absorption coefficient between the two models is smaller than that in the emissivity as discussed above, for the absorption coefficient mainly depends on the number density of the ions in ground state.

Experimental investigation of various type absorber plates for solar air heaters

In this study, four different types’ absorber plates were designed and compared of their energetic performances. These absorber plates were formed as a flat plate (Type I), V-shaped (Type II), wedge-shaped (Type III) and wavy-shaped (Type IV). Each type absorber plate was manufactured in both aluminum (Al) and copper (Cu) materials. Energy efficiencies of the heaters were investigated with airflow velocities of 2, 3 and 4 m s-1 experimentally and compared with each other. The results showed that efficiency of the heater with the copper absorber plate better than aluminum plate however, the resulting air temperature from heater with aluminum absorber plate higher than cooper plate. The experimental results have shown that Type IV and Type II achieved the highest energy efficiency, respectively.

Physical, chemical, and immunohistochemical investigation of the damage to salivary glands in a model of intoxication with aluminium citrate.

Aluminum absorption leads to deposits in several tissues. In this study, we have investigated, to our knowledge for the first time, aluminum deposition in the salivary glands in addition to the resultant cellular changes in the parotid and submandibular salivary glands in a model of chronic intoxication with aluminum citrate in rats. Aluminum deposits were observed in the parotid and submandibular glands. Immunohistochemical evaluation of cytokeratin-18 revealed a decreased expression in the parotid gland with no changes in the submandibular gland. A decreased expression of α-smooth muscle actin was observed in the myoepithelial cells of both glands. The expression of metallothionein I and II (MT-I/II), a group of metal-binding proteins, which are useful indicators for detecting physiological responses to metal exposure, was higher in both glands. In conclusion, we have shown that at a certain time and quantity of dosage, aluminum citrate promotes aluminum deposition in the parotid and submandibular glands, leads to an increased expression of MT-I/II in both the glands, damages the cytoskeleton of the myoepithelial cells in both glands, and damages the cytoskeleton of the acinar/ductal cells of the parotid glands, with the submandibular glands showing resistance to the toxicity of the latter.

Study of the dynamic’s indentation effect with controlled energy on the tribologically transformed surfaces: analysis of microhardness of copper using response surface methodology

Under some conditions of impact, it was possible to cause irreversible changes on the surface of solids. Therefore, we performed impact tests with controlled energy (0.15 mJ) to study the general phenomena of surface degradation in complex conditions. On the other hand, we could establish a capacity to produce tribologically transformed surface (TTS). For the first time, our study is based on an analysis of curves and micrographs to know the evolution of the impact’s effect, and the values of microhardness Vickers and chemical analysis. The micrographic observations illustrate the infiltration of aluminum or tin in copper as veins form, lunures or waves in a lenticular zone (hardened) of copper. In addition, EDX analyzes performed in the aluminum absorption in copper didn’t reveal any alloy formation. The mechanisms responsible for its transformations are unknown, it appears that modelization based on dynamic recrystallization and mechanical alloying or adiabatic shear can provide some answers. Concerning modeling, we have elaborate microhardness model in the case of dynamic indentation by exploiting the response surface methodology (RSM), using a quadratic regression model. Combined effects of four impact parameters on the performance outputs microhardness is explored by a statistical analysis of variance (ANOVA). Results show that the microhardness is influenced principally by nature of samples, nature of ball, and height of projection ball. Also, it is indicated that the penetration depth is the dominant factor affecting the microhardness.

The 19F(p, α0) reaction at low bombarding energy

In a recent experiment performed in Naples by using the TTT-3 tandem accelerator, the 19F(p, α0) reaction has been investigated at low bombarding energies, Ep = 0.6–1 MeV. Excitation functions and angular distributions have been obtained by using several solid state detectors preceded by thin aluminium absorbers. By analysing angular distributions in terms of Legendre and cosine polynomials, a few spectroscopic ambiguities concerning the excited states of the compound nucleus, 20Ne, in the excitation energy region E* = 13.4–13.8 MeV, have been solved. Moreover, this reaction plays an important role for the description of the fluorine nucleosynthesis. For this reason, the astrophysical S-factor has also been extracted and the results have been compared with the literature data.

Experimental Study of Water Heating Efficiency between Aluminium and Copper Absorber Plate in Solar Flat Plate Collector

Solar water heating using flat plate collector (FPC) is the widest application that had been used in residential and commercial area. The material for the absorber plate in FPC should have good thermal conductivity to ensure a high value for the heat removal yet able to store heat slightly high during minimum solar radiation period. An experimental of FPC water heating is conducted using copper and aluminium as absorber plate. The plates were exposed under intense sun radiation more than 800w/m2. The analysis is performed on the relationship between the material and the temperature difference of water. The results represented the heat gain and water heating efficiency between aluminium and copper. Aluminium had heat gain of 1100.69W. Copper had the heat gain of 1025.36W. The water heating efficiency calculated for aluminum is 0.97 while copper is 0.93. The paper finally justified that aluminium is better as the absorber plate in this flat plate solar collector compare to copper plate.

Organic silicon protects human neuroblastoma SH-SY5Y cells against hydrogen peroxide effects.

BackgroundHydrogen peroxide (H2O2) is a toxic agent that induces oxidative stress and cell death. Silicon (Si) is a biological element involved in limiting aluminium (Al) absorption with possible preventive effects in Alzheimer’s disease. However, Si has not yet been associated with other neuroprotective mechanisms.MethodsThe present experiments evaluated in the SH-SY5Y human neuroblastoma cell line the possible role of different Si G5 (50-1000 ng/mL) concentrations in preventing cellular death induced by H2O2 (400 μM, 24 hours).ResultsOur findings showed that H2O2 promoted cell death in the human SH-SY5Y cell cultures and this could be prevented by Si treatment. The loss in cell viability mediated by H2O2 was due to an apoptotic and necrotic process. Apoptotic death was incurred by regulating caspase-8 activity in the extrinsic pathway. The apoptotic and necrotic cell death induced by H2O2 was almost totally reversed by Si (50-500 ng/mL), indicating that it down-regulates both processes in H2O2 treated cells.ConclusionsAccording to our data, Si is able to increase SH-SY5Y cell survival throughout partially blocking cellular damage related to oxidative stress through a mechanism that would affect H2O2/ROS elimination.

Ferric citrate hydrate as a phosphate binder and risk of aluminum toxicity.

Ferric citrate hydrate was recently approved in Japan as an oral phosphate binder to be taken with food for the control of hyperphosphatemia in patients with chronic kidney disease (CKD). The daily therapeutic dose is about 3 to 6 g, which comprises about 2 to 4 g of citrate. Oral citrate solubilizes aluminum that is present in food and drinking water, and opens the tight junctions in the intestinal epithelium, thereby increasing aluminum absorption and urinary excretion. In healthy animals drinking tap water, oral citrate administration increased aluminum absorption and, over a 4-week period, increased aluminum deposition in brain and bone by about 2- and 20-fold, respectively. Renal excretion of aluminum is impaired in patients with chronic kidney disease, thereby increasing the risk of toxicity. Based on human and animal studies it can be surmised that patients with CKD who are treated with ferric citrate hydrate to control hyperphosphatemia are likely to experience enhanced absorption of aluminum from food and drinking water, thereby increasing the risk of aluminum overload and toxicity.

The variation of HVL with focal spot to chamber distance as a function of beam quality for the Pantak Therapax 150 X-ray unit and the implications on dose to water determination using the IPEMB code of practice.

Using a Pantak Therapax SXT 150 system HVL values for clinical beams generated with filters 4-8, were determined as a function of FCD (30-130cm). Aluminium absorbers were placed midway between the focus and chamber with collimation to define both narrow and broad beam geometries. For filters 4-7 with broad beam geometry the HVL initially decreases as the FCD is increased from 30cm and then increases as the FCD approaches 130cm. In contrast filter 8 exhibits a reduction in HVL with increasing FCD attributed to the decreasing influence of absorber scatter. With narrow beam geometry the HVL of filter 4 increases as the FCD is increased. For other filters the HVL variation is similar to that for the broader beam albeit that for a given FCD the HVL is smaller, a consequence of reduced absorber scatter. Monte Carlo BEAMnrc simulations of filter 4-8 beams demonstrated a quality dependent air attenuation effect associated with an increase in HVL for lower quality beams with increasing FCD. Thus for the beams investigated in this work the variation of HVL with FCD can be interpreted in terms of the competing influences of absorber scatter, which tends to decrease the measured HVL, and a quality dependent in air attenuation that tends to increase the HVL with increasing FCD. In terms of an absorbed dose determination it is shown that changes of HVL with FCD resulted in variations of D w,z=0<±0.5%.