ESTIMATION OF BIOACCESSIBILITY OF HEAVY METALS IN OYSTERS USING THE PHYSIOLOGICALLY BASED EXTRACTION TEST

A physiologically based extraction test (PBET) was applied to estimate the oral bioaccessibility of cadmium, mercury, and lead from oyster tissues. The PBET measures the fraction of a metal that is solubilized from the sample under simulated gastric and intestinal conditions. Both gastric and intestinal extracted solutions as well as microwave digested residue were analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES). The bio accessibilities (relative to the total metal concentrations) of cadmium and lead in the oyster samples were 33.8–59.2% and 28.3–51.4%, respectively. The bioaccessibility of mercury was non detectable (<0.019 mg/kg wet weight) due to the relatively low levels of mercury in the oyster samples (<0.110 mg/kg wet weight).     

DETERMINATION OF SELECTED METALS IN ALLIGATOR (Alligator mississippiensis) TISSUES BY INDUCTIVELY COUPLED PLASMA-OPTICAL EMISSION SPECTROMETRY

The results presented in this preliminary study show the concentrations of selected metals in the muscle and bone tissues from the tail of an alligator (Alligator mississippiensis) as determined using inductively coupled plasma-optical emission spectrometry (ICP-OES). Cadmium and lead were not detected above the approximate detection limit of 0.5 µg/g for these two metals by ICP-OES, in either meat or bone tissues. Concentrations (µg/g) (mean ±standard deviation, range) for copper were 8.8 ± 3.8, 6.5–13.1 (meat), and 6.2 ± 3.5, 3.6–10.2 (bone); for iron were 41.9 ± 16.2, 28.8–59.9 (meat), and 26.4 ± 4.4, 21.3–29.0 (bone); and for zinc were 52.8 ± 7.4, 48.0–61.4 (meat), and 42.7 ± 9.0, 34.9–53.2 (bone). The results of copper, iron, and zinc levels were not considered to be potentially toxic to the alligator.     

DETERMINATION OF TRACE AND MAJOR ELEMENTS IN WATER ON OIL PALM PLANTATIONS BY INDUCTIVELY COUPLED PLASMA-OPTICAL EMISSION SPECTROMETRY

The oil palm is an economic crop that has gained worldwide recognition due to its importance. Produce such as the stem, fruits, and leaves contain phytonutrients and antioxidants that are mediators of cellular functions and a cure for various ailments. The oil palm plantations receive inputs of elements from natural and anthropogenic sources. However, while some of the elements are beneficial, they may be toxic at high concentrations. The quality of ground water is important due to the possible uptake of trace and major elements by the oil palm. In this study, the concentrations of fifteen elements in ground water from oil palm plantations in southern Nigeria were measured. The inductively coupled plasma optical emission spectrometer (ICP-OES) was the instrument of choice because of its multielemental capabilities. The study revealed that of the trace elements, the highest concentrations were obtained for lead (Pb) (0.090–10.29 mg/L), while the lowest concentrations were obtained for cadmium (Cd) (0.119–0.391 mg/L). The concentration of the metals were compared with water quality standards established by the World Health Organization in 2011.     

Bioaccessibility of heavy metals in the seaweed Caulerpa racemosa var. corynephora: Human health risk from consumption

This study reports the total and bioaccessible concentrations of heavy metals (Mn, Fe, Cu, Zn, Cd and Pb) in the seaweed Caulerpa racemosa var. corynephora collected from local markets along the Andaman coast of Krabi Province, Thailand. Microwave-assisted acid digestion (EPA Method 3052) was used for sample preparation prior to total metal analysis. The in vitro Unified Bioaccessibility Method (UBM) was applied to assess the bioaccessibility of the metals in the seaweed samples. The total, gastric phase, and residual fraction concentration were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The total amounts found in the seaweed samples, in ascending order were Cd?in vitro bioaccessibility method.     

Determination of uranium in Egyptian graniteic ore by gamma,alpha, and mass spectrometry

Three methods were employed for the determination of uranium in granitic ore rock samples. Gamma spectrometry is a non-destructive technique while alpha spectrometry and inductively coupled plasma–mass spectrometry (ICP-MS) are destructive methods needing application of radiochemical separation before uranium measurement. In gamma spectrometry, the activity concentration of uranium is measured via its daughter (^234mPa) in the decay series, while in alpha spectrometry and inductively coupled plasma mass spectrometry (ICP-MS), the activity concentration of uranium is measured directly. The activity concentrations of uranium in the samples by gamma spectrometry were between 36.7?±?0.5 and 239?±?2.3?Bq g^?1. The activity concentrations of uranium by alpha spectrometry and ICP-MS were from 28.7?±?1 to 145?±?1?Bq g^?1 and 34.3?±?1.4 to 155.9?±?1.6?Bq g^?1, respectively. The ICP-MS and alpha spectrometry methods provided reliable results. The uranium concentrations obtained by gamma spectrometry were, however, systematically too high.     

Erosion of metals using angular silicon carbide particles

ABSTRACT

In this work, erosion tests conducted to evaluate the resistance of two materials, Metal Babbitt Grade 7 and AISI T1 against SiC particles. The erosion rates of these two metals compared with those obtained using AISI D2 steel in a previous work with similar testing conditions. Metal Babbitt and AISI T1 steel selected due to their high ductility and strength, respectively. A test rig similar to that shown in ASTM G76-95 standard used to perform the tests. Silicon carbide particles had a particle size between 350–450 µm. Tests carried out using different impact angles, 30°, 45°, 60° and 90° with a particle velocity of 24 ± 2 m/s and the abrasive flow rate was 0.7 ± 0.5 g/min. SEM photographs used to identify the wear mechanisms on the Babbitt and T1 steel and also obtained cross-section images of the wear scars on metal Babbitt to measure their depth.     

Physiological and histopathological responses of Porcellio laevis (Isopoda,Crustacea) as indicators of metal trace element contamination

This study was designed to assess the impact of the mixture of cadmium (Cd) and zinc (Zn) on the bioaccumulation and the ultrastructural changes in the hepatopancreas of Porcellio laevis (Latreille, 1804) after 4 weeks of exposure to contaminated Quercus leaves under laboratory conditions. For each metal, four concentrations were used with four replicates for each concentration. Metal concentrations in the hepatopancreas and the rest of the body were determined using atomic absorption spectrometry. From the first week until the end of the experiment, a weight gain in P. laevis was observed particularly between the first and the end of exposure from 93.3 ± 18.22 mg fw to 105.22 ± 16.16 mg fw and from 106.4 ± 22.67 mg fw to 125.9 ± 23.9 mg fw for Mix1 and Mix4, respectively. Additionally, the determined metal trace elements (MTE) concentrations in the hepatopancreas were considerably higher compared to those in the rest of the body and seem to be dose‐dependent. Using transmission electron microscopy (TEM), some alterations were highlighted in the hepatopancreas. The main observed alterations were (a) the destruction of the microvilli border in a considerable portion of cells, (b) the increase of the lipid droplets with different shapes and sizes, (c) the increase in the number of the mitochondria, and (d) the appearance of TE in the form of B‐type granules. The obtained results confirmed the ability of P. laevis to deal with high amounts of MTE, suggesting its possible use in future soil's biomonitoring programs.     

Editorial

Automated scanning microphotometry provides an objective assessment of the distribution of metal-bearing (MB) amoebocytes in various tissues of the Pacific oyster, Crassostrea gigas. Silver-staining of these cells in paraffin-embedded sections gave good histochemical enhancement for effective photometric discrimination. Metal-associated pixel fractions (MAPF) for 0.41 mm² tissue-fields were calculated from the results of microphotometric scans, giving an estimate of the metal content and an expression of the population density of MB cells. Gut-associated MB cells in oysters obtained from two geographically-separate metalliferous estuaries had similar distribution patterns, with MAPF values that correlated with metal concentrations in visceral mass determined by atomic absorption spectrophotometry (AAS). The metal content of other tissues varied by two orders of magnitude, the gill having the highest MAPF values. Intermediate MAPF values were found for digestive diverticula and the lowest values in the gonad. There was little difference between gut-associated MB cell populations in oysters from the two collection sites, despite differences in size, glycogen content and gonadal maturation. This non-destructive method of tissue microanalysis may provide a better way of assessing tissue metal-load in individual organisms, and one that is independent of physiological variables.     

Morphology of Co–Cr–Mo dental alloy surfaces polished by three different mechanical procedures

The present study aims at characterizing the three‐dimensional (3‐D) morphology of a Co–Cr–Mo dental alloy surface as a result of three different procedures used for polishing it. The sample surface morphology of the sampled surface was examined employing atomic force microscopy (AFM), statistical surface roughness parameters, and fractal analysis. An extra‐hard dental alloy of cobalt–chromium–molybdenum (Co–Cr–Mo) (Wironit^®, from BEGO, Bremen, Germany) was prepared and moulded. Different polishing treatments were carried out on three groups of six samples each—a total of 18 samples. The first group contained six electropolished (EP) samples. The second group containing six samples went through a mechanical polishing process employing green rubber discs and a high shine polishing paste applied by a rotating black brush (BB). The third group comprising six samples as well went through a mechanical polishing process by means of green rubber discs, high shine polishing paste, and a rotating deer leather brush (DL). Fractal analysis on the basis of a computational algorithm applied to the AFM data was employed for the 3‐D quantitative characterization of the morphology of the sampled surfaces. The fractal dimension D (average ± standard deviation) of 3‐D surfaces for BB samples (2.19 ± 0.07) is lower than that of the DL samples (2.24 ± 0.08), which is still lower than that of the EP samples (2.27 ± 0.09). The results indicated the BB samples as presenting the lowest values of statistical surface roughness parameters, thus the best surface finish, while the EP samples yielded the highest values. Microsc. Res. Tech. 78:831–839, 2015. © 2015 Wiley Periodicals, Inc.     

In situ assessment of the renal microcirculation in mechanically ventilated rats using sidestream dark‐field imaging

For microcirculation research there is a need for baseline data and feasibility protocols describing microcirculation of various organs. The aim of our study was to examine the reliability and reproducibility of sidestream dark‐field (SDF) imaging within the renal cortical microcirculation in rats. Renal microcirculation was observed using SDF probe placed on the exposed renal surface via the upper midline laparotomy. Video sequences recorded intermittently in short apneic pauses were analyzed off‐line by using AVA 3.0 software (MicroVision Medical, Amsterdam, the Netherlands). Results are expressed as mean (SD) or median (25–75% percentiles). We obtained 60 clear sequences from all recorded analyzable videos from all the animals. The total small vessel and all vessel density (in mm.mm^–2) were (28.79 ± 0.40) and (28.95 ± 0.40), respectively. The perfused small and all vessel density were (28.79 ± 0.40) and (28.95 ± 0.40), respectively. The DeBacker Score was (19.14 ± 0.43), the proportion of perfused vessels was 100% (100–100%) and the microvascular flow index was 3.49 (3–3.75). We conclude SDF imaging provides a reliable method to examine the renal microvascular bed in vivo and thus can be used for the study of the renal cortical vascular network in various experimental diseases models and clinical settings.     

INVESTIGATION OF ACID DEPOSITION EFFECTS ON SOUTHERN APPALACHIAN RED SPRUCE (Picea rubens) BY DETERMINATION OF CALCIUM,MAGNESIUM, AND ALUMINUM IN FOLIAGE AND SURROUNDING SOIL USING ICP-OES

Red spruce (Picea rubens) are conifers found at high elevations (above 1370 m) sites in the Southern Appalachian Mountains. A decline of red spruce forests in the Southern Appalachian Mountains caused by atmospheric acid deposition has been reported since the 1970s. Acid deposition leaches essential nutrients (calcium and magnesium) out of the soil and increases the availability of toxic metals (aluminum) to plants. Acid deposition effects on red spruce forests were investigated by determining aluminum, calcium, and magnesium in foliage and surrounding soils using inductively coupled plasma optical emission spectrometry (ICP-OES). There was some correlation in nutrient or toxic metal concentrations found in the foliage or surrounding soils of red spruce trees with respect to elevation and geography of red spruce forests located in the Southern Appalachian Mountains. The majority of the results indicated that foliar nutrient or toxic metal concentrations from red spruce trees did not correlate with soil metal concentrations. Life stage of red spruces trees were independent of foliar or soil metal concentrations. A previously developed model using soil calcium/aluminum molar ratios suggested that almost all sample sites located in the Southern Appalachian Mountains are at high risk of adverse forests health effects. A comparison of red spruce sapling foliar calcium/aluminum ratios at Clingman's Dome, North Carolina/Tennessee, suggested a possible improvement since the 1980s in red spruce forest health. A comparison of sapling red spruce foliar calcium and magnesium concentrations with previous studies, which spanned 40 years, at Richland Balsam, North Carolina, suggested an improvement in red spruce health since 1994.     

Effects of aerobic training,resistance training,or combined resistance‐aerobic training on the left ventricular myocardium in a rat model

This study follows the left ventricular (LV) hypertrophy in rats undergoing aerobic training alone (A), resistance training alone (R), or combined resistance and aerobic training (RA) (usually referred as concurrent training) program. A sedentary control group (C) was included. LV remodeling was evaluated using electron and light microscopy. The LV weight to body weight (LVW: BW) increased 11.4% in A group, 35% in the R group, and 18% in the RA group compared to the C group. The LV thickness increased 6% in the A group, 17% in the R group, and 10% in the RA group. The LV internal diameter increased 19% in the A group, 3% in the R group, and 8% in the RA group compared with the C group. The cross‐sectional area of cardiomyocyte increased by 1% with the A group, 27% with R group, and 12% with RA training. The capillary density increased by 5.4% with A training, 11.0% with R training, and 7.7% with RA training compared with the C group. The volume fraction of interstitial collagen increased by 0.4% with training A, increased by 2.8% with R training, and 0.9% with RA training. In conclusion, except for the LV internal diameter, which increased more in the A group, the cardiac parameters increased more in the R group than in the other groups and in RA group than in A group. Collagen density increased from 5.4 ± 0.8% in the C group to 5.8 ± 0.6% in the A group (n. s.) (P > 0.05), to 8.2 ± 0.7% in the R group (P < 0.05), and to 6.3 ± 0.4% in the RA group (P < 0.05). These results demonstrate a significant increase for collagen content in the LV with R and RA exercise, but the increase was higher with R training alone than with RA training. Microsc. Res. Tech. 77:727–734, 2014. © 2014 Wiley Periodicals, Inc.     

Magneto-rheological engine mount design and experimental characterization

Isolation mounts using magneto-rheological (MR) fluid have increasing potential for various applications. This paper introduces new design and manufacturing aspects of MR engine mounts. CAD software was used to design MR mounts and three different types of MR mount prototypes were considered. Later, magnetostatic analyses were performed to validate the designed configuration of the electromagnetic coil, which controlled the MR fluid flow. The MR mounts were manufactured and, then, tested statically and dynamically using a servo-hydraulic rate machine. Static tests were performed with amplitudes between 0–10 mm. Dynamic tests were performed under excitation frequencies in between 0–100 Hz with amplitudes of ±0.1 mm, ±0.5 mm, ±1.0 mm and ±2.0 mm as well as under excitation frequencies in between 0–20 Hz with amplitudes of ±3.0 mm, ±4.0 mm. Besides the MR mounts, hydro mount and elastomeric top were tested adopting the same procedure. The finding of different mount properties was explained and MR mount characteristics in frequency domain were demonstrated. In addition, the measured characteristics were compared with each other for hydraulic mount and elastomeric top.     

DETERMINATION OF THE EFFECT OF LEMON ADDITION UPON ELEMENT CONCENTRATIONS IN TEA

Consumption of tea is a popular tradition in Turkey. In this article, non essential and toxic element concentrations were determined in infusions and lemon added infusions in widely consumed Turkish teas (black, earl grey, and green tea). Element concentrations were found to be in the order of aluminum > nickel > barium in black and earl grey teas. In green tea, the order was changed to aluminum > nickel > lead > barium. The concentrations of arsenic and antimony were below the detection limit of the inductively coupled plasma optical emission spectrometry method employed. The addition of lemon increased aluminum, cadmium, and lead concentrations in all teas whereas nickel concentration increased in black and green tea but decreased in earl grey. The barium concentration was same at all tea samples. In comparison with the recommended daily allowance ratios, the amount of aluminum consumed is between 13.167–24.396% in males and 17.556–32.528% in females for people who consume 200 mL of teas daily. Other elements (cadmium, lead, nickel, barium) which are a concern for tea consumption were determined and the hazard index of daily tea drinking was found to be in the safe range except for green tea with lemon addition.     

Studies on laser rapid manufacturing of cross-thin-walled porous structures of Inconel 625

An in-house developed continuous wave CO₂ laser-based rapid manufacturing was deployed to fabricate porous structures of Inconel-625 using a new cross-thin-wall fabrication strategy. Studies on the mechanical and metallurgical properties of these porous structures were carried out with laser energy per unit traverse length in the range of 150–300 kJ/m, powder fed per unit traverse length in the range of 16.67–36.67 g/m and transverse traverse index in the range of 0.7–1.3. The processing parametric dependence showed that the powder fed per unit traverse length was a predominating parameter in determining the porosity of the structures, followed by transverse traverse index and laser energy per unit traverse length. The compression testing of fabricated porous structures showed that the material had anisotropy up to 20% for 0.2% yield strength. It was found that the yield strength of the fabricated structures followed the power law and decreased from 423?±?8 MPa for 2.63?±?0.14% porosity to 226?±?6.8 MPa for 11.57?±?0.52% porosity. Scanning electron microscopy showed that shape of the pores was triangular due to the cross-thin-wall fabrication strategy and the observed values of microhardness were in the range 256–370 VHN_0.98N. These studies are expected to augment our knowledge on the fabrication of porous structures with independent control on porosity and yield strength, which are important prerequisites for some of the prosthetic and engineering components in niche areas of applications.     

Structural characterization and tribological evaluation of quince seed mucilage

The mucilage, originating from the seeds of quince fruit was characterized as a potential bio-inspired water-based lubricant. The mucilage consists mainly of fine cellulose nanofibrils and charged hemicelluloses whose structure and properties were characterized here by atomic force microscopy (AFM) and tribological Pin-On-Disc (POD) experiments. The hemicellulose-decorated nanocellulose fibrils were 3.0±0.7 nm in thickness, had a very large aspect ratio and also had a tendency to self-align when dried on mica surface. Macroscale tribological tests showed that the mucilage was able to reduce the coefficient of friction of polyethylene/stainless steel contact to values below 0.03. Thus, we show that quince mucilage is a native nanocellulose material with a notable ability to lower friction.     

An experimental method for calibration of the plasmon mean free path

Transmission electron microscopy specimens in the form of elongated, conical needles were made using a dual‐beam focused ion beam system, allowing the specimen thickness to be geometrically determined for a range of thickness values. From the same samples electron energy loss maps were acquired and the plasmon mean free path (λ) for inelastic scattering was determined experimentally from the measured values of specimen thickness. To test the method λ was determined for Ni (174 ± 17 nm), α‐Al₂O₃ (143 ± 14 nm), Si (199 ± 20 nm) and amorphous SiO₂ (238 ± 12 nm), and compared both to experimental values of λ taken from the literature and to calculated values. The calculated values of λ significantly underestimate the true sample thickness for high accelerating voltages (300 kV) and large collection angles. A linear dependence of λ on thickness was confirmed for t/λ < 0.5–0.6, but this method also provides an approach for calibrating λ at sample thicknesses for which multiple scattering occurs, thus expanding the thickness range over which electron energy loss spectroscopy can be used to determine the absolute sample thickness (t/λ > 0.6). The experimental method proposed in this contribution offers a means to calibrate λ for any type of material or phase that can be milled using a focused ion beam system.     

A calorimeter for detecting hadrons with energies of 10–100 GeV

A calorimeter for detecting hadrons in the energy range 10–100 GeV is described. It is used at CERN in the NA58 (COMPASS) experiment aimed at studying the nucleon structure and spectroscopy measurements of charmed particles. The calorimeter is composed of 480 modules with a cross section of 15×15 cm², assembled in a matrix with dimensions of 4.2×3 m² and a central window of area 1.2×0.6 m². In each module are 40 iron and scintillator layers of a total thickness of 4.8 interaction lengths. The energy resolution of the calorimeter for hadrons (pions) and electrons and the spatial resolution, determined on the test beams, are $\frac{{\sigma _\pi (E)}}{{E[GeV]}} = \frac{{59.4 \pm 2.9}}{{\sqrt E }} \oplus (7.6 \pm 0.4)\% ;\frac{{\sigma _e (E)}}{{E[GeV]}} = \frac{{24.6 \pm 0.7}}{{\sqrt E }} \oplus (0.7 \pm 0.4)\% $ , and σ _x,y ≈ 15 mm, respectively. The average value of the e/π ratio that characterizes the amplitude responses of the calorimeter to electrons and pions with equal energies from the above range is 1.2 ± 0.1. This study was performed at the JINR Laboratory for Particle Physics.     

Elemental changes in the brain, muscle, and gut cells of the housefly, Musca domestica, exposed to heavy metals

The toxic effects of heavy metals on organisms are well established. However, their specific action at the cellular level in different tissues is mostly unknown. We have used the housefly, Musca domestica, as a model organism to study the toxicity of four heavy metals: copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb). These have been fed to larvae at low and high, semi-lethal concentrations, and their accumulation in the head, thorax, and abdomen was subsequently measured in adult flies. In addition, their impact on the cellular concentration of several elements important for cell metabolism-sodium (Na+), magnesium (Mg++), phosphorous (P), sulphur (S), chloride (Cl-) and potassium (K+)-were measured in neural cells, muscle fibers, and midgut epithelial cells. Our study showed that the heavy metals accumulate mainly in the abdomen, in which the concentrations of two of the xenobiotic metals, Cd and Pb, were 213 and 23 times more concentrated, respectively, than in controls. All the heavy metals affected the cellular concentration of light elements in all cell types, but the changes observed were dependent on tissue type and were specific for each heavy metal, and its concentration.     

The Lubrication of Steel by Electroplated Gold

Sliding friction between an 1/8 in. spherical steel rider and a gold-plated steel flat was measured for various loads (200–2000 gm), gold film thicknesses (0.1–10 μ) and steel combinations (440C and 52100). Coefficient of friction recorded in each run for 100 traverses was found to be most sensitive to the rider material (0.1–0.3 with 440C rider and 0.1–0.6 with 52100 rider, as compared to 0.6–0.7 for unlubricated steel). With a 52100 rider, as the number of traverses increase three distinct types of frictional behaviors were found: (A) slowly decreasing, (B) rapidly decreasing, and (C) increasing (sometimes a minimum was first reached). Theoretical coefficient of friction (0.1) was only observed with 'Type B' results. With a chromium rich 440C rider, friction was always low presumably due to its low affinity to gold.