Variation In Mineral Content Research Articles

Thermal conductivity of short sequences of rock

Numerical models of igneous rock samples provide estimates of the variation in conductivity of discs cut from lengths of core. Ten discs cut from a piece of core have a root mean squared deviation of up to 6 %, depending on quartz content and crystal size. Greater crystal size increases the apparent conductivity of a disc by up to 3.2 % when quartz content is 49 %, but less when quartz content is 30 % or less. Measured conductivity depends on the thickness of the measured disc. When quartz content is low, this difference is well within the normal limits of experimental error, but when quartz content is high, the apparent conductivity will be within the normal limits of experimental error only when the disc is at least 8 mm thick. The estimation of contact resistance between the sample and the bar by using sets of discs of different thickness is unreliable because of variation in mineral content between contiguous discs. Better representation of the conductivity profile is obtained by measuring single discs with an estimation of the contact resistance.

Effects of mineral distribution at mesoscopic scale on solute diffusion in a clay‐rich rock: Example of the Callovo‐Oxfordian mudstone (Bure, France)

The mesostructure (millimeter to micrometer scale) of clay‐rich sedimentary rocks is generally characterized by a connected fine‐grained clay matrix embedding coarser nonclay minerals. We use the Callovo‐Oxfordian clay‐rich rock formation (France) to illustrate how mesostructure influences solute transfer in clay‐rich rocks at larger scales. Using micrometer resolution imaging techniques (SEM and micro‐CT) major mineral phases (clay matrix, carbonates, tectosilicates, and heavy minerals) were mapped both in two dimensional (2‐D) and three dimensional (3‐D) at the mesoscale. Orientation and elongation distributions of carbonate and tectosilicate grains measured on mineral maps reveal an anisotropic mesostructure relative to the bedding plane, in agreement with the geological history of the sedimentary rock. Diffusion simulations were performed based on the 3‐D mineral maps using a random walk method thus allowing direct computation of mesoscopic scale‐related diffusion anisotropy and tortuosity. Considering an isotropic clay matrix, simulated diffusion anisotropy (1.11–1.26) was found lower than the one experimentally measured on macroscopic samples (1.5 to 2), due to the anisotropy feature of pores within the clay matrix. The effects of the mineral content variations on diffusion properties were then investigated by numerical modifications of a mineral map combined with diffusion simulations. Evolution of the tortuosity and diffusion anisotropy with the clay matrix content were successfully interpreted by the Koponen percolation/diffusion model, whereas the Archie approach fails to reproduce diffusion properties at low clay contents. A comparison of fitting parameters with those obtained experimentally indicates that diffusion coefficient variations observed at a large scale could be mainly controlled by the mesostructure.

Remineralisation by Chewing Sugar-Free Gums in a Randomised, Controlled in situ Trial Including Dietary Intake and Gauze to Promote Plaque Formation

Remineralisation has been shown to be an effective mechanism of preventing the progression of enamel caries. The aim of this double-blind, randomised, cross-over in situ study was to compare enamel remineralisation by chewing sugar-free gum with or without casein phosphopeptide amorphous calcium phosphate (CPP-ACP) where the enamel lesions were exposed to dietary intake and some were covered with gauze to promote plaque formation. Participants wore removable palatal appliances containing 3 recessed enamel half-slabs with subsurface lesions covered with gauze and 3 without gauze. Mineral content was measured by transverse microradiography, and plaque composition was analysed by real-time polymerase chain reaction. For both the gauze-free and gauze-covered lesions, the greatest amount of remineralisation was produced by the CPP-ACP sugar-free gum, followed by the gum without CPP-ACP and then the no-gum control. Recessing the enamel in the appliance allowed plaque accumulation without the need for gauze. There was a trend of less remineralisation and greater variation in mineral content for the gauze-covered lesions. The cell numbers of total bacteria and streptococci were slightly higher in the plaque from the gauze-covered enamel for 2 of the 3 treatment legs; however, there was no significant difference in Streptococcus mutans cell numbers. In conclusion, chewing sugar-free gum containing CPP-ACP promoted greater levels of remineralisation than a sugar-free gum without CPP-ACP or a no-gum control using an in situ remineralisation model including dietary intake irrespective of whether gauze was used to promote plaque formation or not.

AFM Imaging of Milk Casein Micelles: Evidence for Structural Rearrangement upon Acidification

Milk casein micelles are natural association colloids that we all encounter in everyday life, yet we still lack an accurate description of their internal structure and the interactions that stabilize it. In this letter, we provide for the first time detailed images of intact casein micelles as obtained through atomic force microscopy under liquid conditions close to physiological. The micelles appear as heterogeneous raspberry-like particles, which is consistent with a hierarchical/spongelike structure made of connected 10-40 nm dense casein regions. Upon in situ acidification to pH 5, the micelles decrease in size and lose their surface heterogeneities, indicating that this structure is highly sensitive to variations in mineral content and caseins net charge.

The content of mineral elements on whole blood and hair in Moschus sifanicus

The mineral content of forage, whole blood and hair samples of Moschus sifanicus were analyzed and compared with those of local goats. The results indicated that the selenium content of 10 kinds of foliage was lower than the nutrient standards set for herbivores by the National Research Council. The Cu, Mn, Zn, Ca and Mg content of hair was significantly higher than those in whole blood; however, Fe content was the reverse. All elements had concentration distribution, and the variation of mineral content in whole blood and hair of M. sifanicus was small. Key words: Moschus sifanicus , blood and hair, mineral elements.

Did Major Impacts Affect Sedimentologic/Sequence-Analytical Pattern of the Early Palaeozoic Sedimentary Systems of Jordan, Arabian Plate?

Based on profound sequence-analytical data of the early Palaeozoic sedimentary systems of Jordan, Arabian Plate, a correlation attempt is proposed with regard to possible major impact events after Price [10]. His methodological concept tells that abrupt 441 Ma. Referring to the fact that major impacts may trigger, respectively influence, exogenic and endogenic processes on an over-regional, even global, extent, this paper put the “sensitive” geological setting of Jordan at the Arabian Platform’s margin into focus. That mainly concerns the early Palaeozoic coastlines as to sea level change as well as the Jordan Valley Rift as being possibly to susceptible for tectonic re-activation changes of both direction and speed of plate motions would indicate such convulsive processes as occurred on: 550 Ma, 526.5 Ma, 514 Ma, 502 Ma, 456/455.4 Ma, and following triggering of magmatism at the Precambrian/Cambrian boundary. The following phenomena are taken into account: Faulting and magmatism triggered along the Jordan Valley Rift (Wadi Araba) in connection with the Pan-African Orogeny, anoxic sediments, temporary high detrital input onto the adjoining stable platform from Gondwana hinterlands, and significant chemical weathering in the Gondwana source areas by intensive acid (nitric) rain directing mineral content variation in the “Nubian Sandstones” (e.g. feldspar, kaolinite/dickite, tourmaline).

Quantitative analysis of iron oxide concentrations within Aptian–Albian cyclic oceanic red beds in ODP Hole 1049C, North Atlantic

Aptian–Albian sediments in Core 12X of Hole 1049C (ODP Leg 171B) are characterized by high-frequency cycles that consist of alternating layers of red and green/white clayey chalk, and claystone. The first derivative curves of diffuse reflectance spectra (DRS) for samples of different colors reveal that red (brown and orange) samples show clear peaks corresponding to hematite and goethite. Following treatment using the CBD (citrate-bicarbonate-dithionite) procedure, the red samples lost their red color and corresponding peaks in the first derivative curve, and became greenish or whitish. Therefore, hematite and goethite are the minerals responsible for the reddish change in sample color. However, these minerals behave differently from each other in terms of determining the color of sediment: hematite imparts a red color, whereas goethite imparts a yellow color. Therefore, a change in the proportions of hematite and goethite can cause a change in sediment color from orange to brown. To obtain the absolute contents of iron oxides in these sediments, we performed a quantitative analysis using DRS with multiple linear regression. The results reveal that the Albian brown beds contain 0.13–0.82% hematite (average value, 0.51%) and 0.22–0.81% goethite (average value, 0.58%). The Aptian orange beds contain 0.19–0.46% hematite (average value, 0.35%) and 0.29–0.67% goethite (average value, 0.50%). X-ray diffraction analysis of the Aptian and Albian cycles reveals no clear variations in mineral content with sediment color. It is suggested that hematite and goethite were derived from oxic environments during the period of deposition and early diagenesis. The oxic conditions were probably determined by the low accumulation rate of organic matter and the high content of dissolved oxygen in bottom water.

Genetic analysis identifies quantitative trait loci controlling rosette mineral concentrations in Arabidopsis thaliana under drought

Rosettes of 25 Arabidopsis thaliana accessions and an Antwerp-1 (An-1) x Landsberg erecta (Ler) population of recombinant inbred lines (RILs) grown in optimal watering conditions (OWC) and water deficit conditions (WDC) were analysed for mineral concentrations to identify genetic loci involved in adaptation of mineral homeostasis to drought stress. Correlations between mineral concentrations were determined for accessions and a quantitative trait locus (QTL) analysis was performed for the RIL population. Plant growth and rosette mineral contents strongly decreased in WDC compared with OWC. Mineral concentrations also generally decreased, except for phosphorus (P), which remained constant, and potassium (K), which increased. Large variations in mineral concentrations were observed among accessions, mostly correlated with total rosette leaf area. Mineral concentration QTLs were identified in the RIL population, but only a few were common for both conditions. Clusters of mineral concentration QTLs often cosegregated with dry weight QTLs. Water deficit has a strong effect on rosette mineral status. This is genetically determined and seems largely a pleiotropic effect of the reduction in growth. The low number of common mineral concentration QTLs, shared among different RIL populations, tissues and conditions in Arabidopsis, suggests that breeding for robust, mineral biofortified crops will be complex.

Phenotypic variation of mineral contents in beef

Humans have a daily minimal requirement for minerals, of which beef can be a major supply. However, it is unknown to what extent the contents of minerals vary in beef. Thus an objective of this study was to determine the extent of phenotypic variation of mineral contents in beef. Beef longissimus dorsi muscle samples were collected from 1086 head of purebred Angus cattle, trimmed off external connective and adipose tissue, and freeze ground before mineral assays. After microwave digestion, concentrations of iron, zinc, magnesium, phosphorus, potassium and sodium were measured by ICP‐OES. The mean values ± SE for the six minerals (based on wet weight) are 13.97 μg/g ± 0.09, 39.98 μg/g ± 0.35, 219.94 μg/g ± 0.94, 1772.14 μg/g ± 9.68, 3083.61 μg/g ± 21.35, and 434.77 μg/g ± 2.44, respectively. Nearly two‐fold concentration differences were observed between the upper 90% and the lower 10% in most minerals. Significant correlations between mineral contents were also found. The large mineral content variations in beef indicate that it may be possible to improve the nutrient contents of beef thereby making it even better source of nutrients.Research support: PFIZER INC. Animal Health Division and Affiliates

Genetic Variation in Mouse Femoral Tissue-Level Mineral Content Underlies Differences in Whole Bone Mechanical Properties

A/J mice, as compared to C57BL/6J (B6) mice, have a significantly greater total femoral mineral (ash) content which correlates with an increased femoral stiffness (resistance to deformation), but also with an increased brittleness (catastrophic failure). To determine if this whole bone variation in mineral content is indicative of significant mineral and/or matrix variation at the tissue level, femora from 16-week-old female A/J and B6 mice were isolated, embedded in PMMA, sectioned and mounted on barium fluoride infrared windows for FTIRI analyses. In addition, preliminary studies of femora from C3H/HeJ (C3H) mice were conducted, since they have an ash content intermediate to A/J and B6. Mean values for mineral-to-matrix ratio were significantly different for A/J (8.4 ± 0.8) and B6 (7.5 ± 0.4), as were values for collagen cross-link maturity (1.8 ± 0.05 and 3.2 ± 0.1, respectively). C3H mice appeared to have a mineral-to-matrix ratio intermediate of A/J and B6, and cross-link maturity greater than both A/J and B6. B6 femora had similar carbonate-to-amide ratios, carbonate-to-mineral ratios and acid phosphate levels. Thus, whole bone differences in mineral content are concurrent with tissue-level variation in mineral content and collagen maturity in inbred mice. The greater stiffness and brittleness of A/J femora are likely due to differential biological control (osteoblast activity) of the amount of mineral.

Variation of mineral content in different cultivars of bitter melon collected from Japan and The Philippines

Bitter melon (Momordica charantia L., Cucurbitacae) is a health-promoting vegetable and medicinal plant and now widely used as a dietary supplement. This paper describes the mineral (calcium, copper, iron, magnesium, manganese and zinc) contents in 10 different cultivars of bitter melon collected from Japan and Philippines. Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) was used to determine the mineral content. The Japanese cultivar Nikko contained the highest amount of Fe (218µg/g) & Mg (2481µg/l) and the cultivar Kyushu contained the highest amount of Mn (75µg/g) & Zn (41µg/g). Erabu was the the highest calcium (1896 ug/g) content cultivar and Dragon was the highest copper (16µg/g) content cultivar. The Philippines bitter melon Cultivar Verde Buenas performed to produce the highest amount of Ca (2032µg/g), Fe (206µg/g) and Mn (80µg/g) and the cultivars Sta Monica contained the highest amount of Cu (12µg/g)& Mg (2433µg/g) and the cultivar Galaxy produced the highest amount of Zn (47µg/g). The Japanese cultivar Erabu and the Philippines cultivar Trident 357 contained the lowest amount of Cu, Mg, Mn and Zn.

The contribution of mineral to the material properties of vertebral cartilage from the smooth-hound shark Mustelus californicus

Elasmobranch vertebral cartilage has a substantial mineral fraction (39-55%) and the arrangement of mineral varies among species. We examined vertebrae from one shark species, Mustelus californicus, to determine mineral content, the effect of mineral on material properties and the viscoelastic response of vertebral cartilage. We serially demineralized vertebrae and compressively tested them to failure at varying strain rates. Mineral in vertebral cartilage varies within individuals, intraspecifically and interspecifically; this is in contrast to bone, in which significant variation in mineral content is pathological or an interspecific effect. Within Mustelus, vertebrae with larger mineral fractions were significantly stiffer and stronger; however when variation is assessed across species, the structure has a larger effect. Shark vertebral cartilage did not show a substantial viscoelastic response at biologically relevant strain rates, validating the use of quasistatic testing for this material.

Regional variation in the microhardness and mineral content of porcine long bones

Pig carcasses are frequently used as models for the human cadaver in the study of trauma and wound patterns. Limited availability and ethical concerns over the use of human tissue has meant that porcine bone is often used as a substitute for human bone in such studies. However, there is a lack of comprehensive mechanical data to make informed decisions on the choice of model to account for variations in the age, sex and body mass. In this study, variation in the properties of cortical bone along the length of the porcine humerus and ulna, from five female pigs aged over 36 months, was investigated by using Vickers microhardness tests. Transverse sections were taken from the proximal, mid and distal regions of the diaphyses, and tests were carried out in the anterior, medial, posterior, and lateral quadrants. Microhardness was also measured across the cortex from the periosteal to endosteal surfaces. Regional variation in mineral content was explored by analysing samples, taken immediately adjacent to the hardness tests, using Atomic Absorption Spectroscopy. Mechanical data are discussed in relation to mineral content, morphology and loading of the limbs, within a forensic context.

Iron, zinc and phytic acid content of selected rice varieties from China

AbstractRice is the major Chinese staple food (per capita approx 250 g day−1) and, as such, is an important source of essential minerals. However, due to a number of factors the bio‐availability of these minerals is limited. In this study, the variation of phytic acid (PA), iron (Fe) and zinc (Zn) levels in 56 varieties of Chinese rice was investigated. The samples included in this study were collected in proportion to the importance of the rice‐growing regions in China. Fe levels showed the biggest variation (9–45 mg kg−1) and were not related with PA content or grain shape although growing locations were identified yielding higher (25.2 mg kg−1) and lower (14.2 mg kg−1) Fe levels. Zn showed a moderate variability (13–39 mg kg−1), which was narrower than for Fe, while broader than for PA (7.2–11.9 g kg−1). Zn content is correlated (R2 = 0.5; P < 0.01) with PA content, and shows a relation with growing region and kernel shape. Variation of PA content is the least among the three components. Molar ratios of PA to Fe and Zn ranged from 15 to 105 and 27 to 67, respectively. The results of the mineral contents and PA content can be interpreted in terms of expected bio‐availability. This study shows that the mineral bio‐availability of Chinese rice varieties will be <4%. Despite the variation in mineral contents, in all cases the PA present is expected to render most mineral present unavailable. We conclude that there is scope for optimisation of mineral contents of rice by matching suitable varieties and growing regions, and that rice products require processing that retains minerals but results in thorough dephytinisation. Copyright © 2006 Society of Chemical Industry

Mineral content of longissimus dorsi thoracis from water buffalo and Zebu-influenced cattle at four comparative ages

The longissimus dorsi thoracis (LDT) of 64 water buffalo and 68 Zebu-influenced cattle was used to determine the mineral content variation (mg/100 g of fresh tissue) according to species, age (7, 17, 19 and 24 months-of-age, MOA) and gender (steers and bulls). Buffalo LDT had higher concentrations of K, Mn, Fe, Zn and Cu at weaning ( P < 0.05). Phosphorous content was higher ( P < 0.05) at post-weaning ages. Mineral profile was affected by age without clear trends; the Na and K contents increased at 24 MOA. The age × species, age × gender and species × gender interactions affected ( P < 0.05) Fe content that ranged from 1.74 to 2.56 mg/100 g fresh tissue. Meat from both species contributes with more of 25% of K, P, Fe and Zn of the daily requirement for an adult.

Mineral content changes in bone associated with damage induced by the electron beam

Energy-dispersive x-ray (EDX) spectroscopy and backscattered electron (BSE) imaging are finding increased use for determining mineral content in microscopic regions of bone. Electron beam bombardment, however, can damage the tissue, leading to erroneous interpretations of mineral content. We performed elemental (EDX) and mineral content (BSE) analyses on bone tissue in order to quantify observable deleterious effects in the context of (1) prolonged scanning time, (2) scan versus point (spot) mode, (3) low versus high magnification, and (4) embedding in poly-methylmethacrylate (PMMA). Undemineralized cortical bone specimens from adult human femora were examined in three groups: 200x embedded, 200x unembedded, and 1000x embedded. Coupled BSE/EDX analyses were conducted five consecutive times, with no location analyzed more than five times. Variation in the relative proportions of calcium (Ca), phosphorous (P), and carbon (C) were measured using EDX spectroscopy, and mineral content variations were inferred from changes in mean gray levels ("atomic number contrast") in BSE images captured at 20 keV. In point mode at 200x, the embedded specimens exhibited a significant increase in Ca by the second measurement (7.2%, p < 0.05); in scan mode, a small and statistically nonsignificant increase (1.0%) was seen by the second measurement. Changes in P were similar, although the increases were less. The apparent increases in Ca and P likely result from decreases in C: -3.2% (p < 0.05) in point mode and -0.3% in scan mode by the second measurement. Analysis of unembedded specimens showed similar results. In contrast to embedded specimens at 200x, 1000x data showed significantly larger variations in the proportions of Ca, P, and C by the second or third measurement in scan and point mode. At both magnifications, BSE image gray level values increased (suggesting increased mineral content) by the second measurement, with increases up to 23% in point mode. These results show that mineral content measurements can be reliable when using coupled BSE/EDX analyses in PMMA-embedded bone if lower magnifications are used in scan mode and if prolonged exposure to the electron beam is avoided. When point mode is used to analyze minute regions, adjustments in accelerating voltages and probe current may be required to minimize damage.

Influence of the Nest Environment on Bone Mineral Content in Hatchling Painted Turtles (Chrysemys picta)

We performed an experiment at a field site in north-central Nebraska to assess the role of the nest environment in inducing variation in bone mineral content in hatchling painted turtles Chrysemys picta (Schneider 1783). The contents of several newly constructed nests were manipulated by reciprocal transplant, after which the eggs were allowed to incubate for 8 wk under natural conditions. The nests were then excavated, and the eggs were brought into the laboratory to complete incubation and hatch under standard conditions of temperature and moisture. The hatchlings were killed, and their carcasses and residual yolks were analyzed separately for calcium and phosphorus. More of the random variation in carcass calcium and phosphorus was related to the nest in which eggs incubated (37% and 42%, respectively) than was associated with the clutch of origin (21% and 37%). Moreover, hatchlings from some nests contained substantially more calcium and phosphorus than did hatchlings from other nests, both in terms of the absolute amounts of the elements in their carcasses (pointing to variation in body size) and in terms of the concentrations of those elements (pointing to variation in bone density). The amounts of calcium and phosphorus in carcasses of hatchlings were positively correlated with changes in mass of their eggs during the 8 wk that the eggs incubated in nests in the field, thereby indicating that the influence of the nest environment on developing embryos probably was mediated by water exchanges experienced by the eggs. These findings indicate that developmental plasticity underlies a major fraction of the variation in mineral content of hatchling painted turtles emerging from nests in the field. Phenotypic variation attributable to plasticity consequently needs to be addressed in models for life-history evolution of painted turtles and other chelonians producing eggs with soft, flexible shells.

Comparative evaluation of the peri-implant bone tissue mineral density around unloaded titanium dental implants

The mechanical properties of bone are greatly influenced by the percentages of organic and mineral constituents. Nevertheless, the information about the mineral content on a microscopic scale in peri-implant bone is scarce. The aim of this work was to analyze the bone mineral density of peri-implant bone under different techniques. Five unloaded titanium dental implants with a micro-structured surface (three XiVE plus and two Frialit 2, DENTSPLY-Friadent, Mannheim, Germany) were retrieved from the mandible of five patients after a 6-month period. scanning electron microscopy with backscattered electron signal (BSE), light microscopy (LM) with a double staining technique, fluorescence microscopy and confocal laser microscopy were used for measuring microscopic mineral content variations in peri-implant bone. Histomorphometry and image intensity (grey level) were evaluated using a software package for image analysis. The low mineral density index (LMDI) for LM was of 29.2+/-3.1 (mean+/-S.D.), while the high mineral density index (HMDI) was of 88.2+/-3.6 (mean+/-S.D.). The one-way ANOVA analysis showed a significant difference (P<0.001) among the groups. The pairwise Holm-Sidak test identified the differences among HMDI indexes for both LM and SEM values and also for cross-evaluation of the LMDI and HMDI values. The comparison between LMDI indexes for both SEM and LM did not show any significance. The fluorescence microscopy analysis showed clearly the difference between old (high mineralized) and new (low mineralized) bone tissue near the implant surface. Under confocal laser microscopy the same sections showed the area of bone modelling closest to implant surface. In this study it was found that bone around unloaded implants showed a low mineral density index under all the investigation methods used. It was also found that the conventional LM technique with the double staining method was able to intensely stain the bone area with a low mineral content.

Propagation of high-alkaline fluids in an argillaceous formation: Case study of the Khushaym Matruk natural analogue (Central Jordan)

The Khushaym Matruk site in Central Jordan is investigated as a natural analogue of a deep geological repository for intermediate to high-level radioactive wastes to discuss the impact of high-alkaline solutions in an argillaceous formation. The studied site is characterised by Maestrichtian bituminous-rich marls, consisting of 66–83% of carbonates and 10–15% of clays of mixed-layers illite–smectite type (I–S), overlapped by a marble/cement unit formed by spontaneous in situ combustion of the sedimentary organic matter in sub-surface conditions. This high-temperature event produced marble and cementitious phases typical to those observed in industrial cements whose alteration generates high-alkaline solutions. Evidences of fluid circulations in Khushaym Matruk site are underlined by secondary minerals, mainly calcite and gypsum, neoformed in cracks and micro-cracks crosscutting the bituminous-rich marls, and in travertines capping them. The chemical and Sr isotopic data of these phases are characteristics of high-alkaline fluids generated by alteration of the cementitious phases and having percolated with partial equilibration in the underlying bituminous-rich marls. The propagation of these alkaline solutions by structural discontinuity paths in the clayey formation is underlined over distances greater than 5 m. Also, the mineralogical and petrographic characterisation of the bituminous-rich marls, far and close to the marble/cement unit, emphasizes slight variations in mineral contents, a few metres close to the marble/cement contact, with notably a decrease of I–S crystallinity, a change from beideillite to montmorillonite type and, calcite and zeolite recrystallisation. Together, textural disturbances of these rocks, underlined by micro-fissuration of the sedimentary matrix, are observed. A pervasive circulation of high-alkaline fluids in the argillaceous matrix is proposed to explain these changes and is underlined over a distance of a few metres under the contact with the marble/cement unit. Cathodoluminescence observations and U–Th radioactive disequilibrium dating applied on infilling calcite cracks indicate that these circulations were not continuous but occurred in several steps with a mean age of 110,000–130,000 years.

Variation in Mineral Concentrations in Breast Milk of Guatemalan Mothers and a Tribute to Professor Clive E. West

Variation in Mineral Concentrations in Breast Milk of Guatemalan Mothers and a Tribute to Professor Clive E. West