A coded aperture microscope for X-ray fluorescence full-field imaging

The design and construction of an instrument for full-field imaging of the X-ray fluorescence emitted by a fully illuminated sample are presented. The aim is to produce an X-ray microscope with a few micrometers spatial resolution, which does not need to scan the sample. Since the fluorescence from a spatially inhomogeneous sample may contain many fluorescence lines, the optic which will provide the magnification of the emissions must be achromatic, i.e. its optical properties must be energy-independent. The only optics which fulfill this requirement in the X-ray regime are mirrors and pinholes. The throughput of a simple pinhole is very low, so the concept of coded apertures is an attractive extension which improves the throughput by having many pinholes, and retains the achromatic property. Modified uniformly redundant arrays (MURAs) with 10 µm openings and 50% open area have been fabricated using gold in a lithographic technique, fabricated on a 1 µm-thick silicon nitride membrane. The gold is 25 µm thick, offering good contrast up to 20 keV. The silicon nitride is transparent down into the soft X-ray region. MURAs with various orders, from 19 up to 73, as well as their respective negative (a mask where open and closed positions are inversed compared with the original mask), have been made. Having both signs of mask will reduce near-field artifacts and make it possible to correct for any lack of contrast.

High-sensitivity nanoscale chemical imaging with hard x-ray nano-XANES

Resolving chemical species at the nanoscale is of paramount importance to many scientific and technological developments across a broad spectrum of disciplines. Hard x-rays with excellent penetration power and high chemical sensitivity are suitable for speciation of heterogeneous (thick) materials. Here, we report nanoscale chemical speciation by combining scanning nanoprobe and fluorescence-yield x-ray absorption near-edge structure (nano-XANES). First, the resolving power of nano-XANES was demonstrated by mapping Fe(0) and Fe(III) states of a reference sample composed of stainless steel and hematite nanoparticles with 50-nm scanning steps. Nano-XANES was then used to study the trace secondary phases in lithium iron phosphate (LFP) particles. We observed individual Fe-phosphide nanoparticles in pristine LFP, whereas partially (de)lithiated particles showed Fe-phosphide nanonetworks. These findings shed light on the contradictory reports on Fe-phosphide morphology in the literature. Nano-XANES bridges the capability gap of spectromicroscopy methods and provides exciting research opportunities across multiple disciplines.

Bioaccessibility of Cd and Pb in tailings from a zinc smelting in Brazil: implications for human health

Soils and wastes enriched with heavy metals may present ecological and human health risks. A considerable number of mining areas exist in Brazil, where high levels of metals have been found. However, studies of bioaccessibility of metals in soils/tailings from these areas are scarce, despite their potential informational contribution concerning exposure risks of residents near these areas. This study evaluated tailings collected from four sites of a zinc smelting area located in Brazil with aims to: (1) evaluate the presence of metals of potential concern; (2) investigate Cd and Pb bioaccessibility; and (3) determine the desorption kinetics of Cd and Pb. High concentrations of total Cd and Pb (up to 1743 mg Cd kg(-1) and 8675 mg Pb kg(-1)) and great variability were found in the tailings, indicating the importance of adequate planning for their final disposal, in order to avoid contamination in the surrounding environment. Cadmium and Pb bioaccessibility percentages in the intestinal phase were less than 47 and 4 %, respectively, which represents significant fractions not available for absorption in the intestinal tract. However, this material has to be monitored since its bioaccessibility may increase with eventual physicochemical changes, releasing Cd and Pb. Desorption kinetics experiments revealed that Pb in the samples remained in less labile fractions, whereas Cd was found in more labile fractions, which is in accordance with the bioaccessibility results.

Investigation of arsenic species in tailings and windblown dust from a gold mining area

Research has shown the presence of high levels of arsenic (up to 2666 mg As kg(-1)) in tailings from a gold mining area of Brazil. This is an important point of attention, generating concerns about impacts on human health. Yet, a recent study showed that As bioaccessibility in the same area was very low (<4.4%). Thus, determination of the direct solid-phase speciation of As in the mine tailings and windblown dust is needed to explain this low bioaccessibility. Mine samples were collected from four subareas and windblown dust from eight sites. Synchrotron-based bulk-X-ray absorption near-edge structure (bulk-XANES) spectroscopy, micro-X-ray absorption near-edge structure (μ-XANES), and μ-X-ray fluorescence (μ-SXRF) spectroscopy were applied to determine As speciation. Bulk-XANES spectra indicated that As occurs as the As(V) oxidation state. Micro-XANES and μ-SXRF analyses revealed that As was also present as arsenopyrite (FeAsS) and its weathering products, but mostly it was As(V) as poorly crystalline ferric arsenate. This supports the findings of low bioaccessible As and highlights the importance of Fe oxides in immobilizing As in the terrestrial environment. All air particulate samples exhibited As-rich particles (up to 313 mg As kg(-1)). The air particulates exhibited solid-phase As species very similar to those found in the mine samples, which indicates that As in the windblown dust is not easily available.

Parathyroid hormone response to severe vitamin D deficiency is sex associated: an observational study of 571 hip fracture inpatients

OBJECTIVES

To investigate the association between sex and parathyroid hormone response to severe vitamin D deficiency after hip fracture.

DESIGN

Cross-sectional study.

SETTING

Rehabilitation hospital in Italy.

PARTICIPANTS

571 consecutive inpatients with hip fracture and severe vitamin D deficiency (serum 25-hydroxyvitamin D < 12ng/ml), without hypercalcemia or estimated glomerular filtration rate (GFR) < 15ml/min.

MEASUREMENTS

In each patient we assessed PTH (by two-site chemiluminescent enzyme-labelled immunometric assay), 25-hydroxyvitamin D (by immunoenzymatic assay), albumin-adjusted total calcium, phosphate, magnesium, and creatinine 21.3 ± 6.1 (mean ± SD) days after fracture occurrence. Functional level was assessed using the Barthel index. PTH response to vitamin D deficiency was classified as either secondary hyperparathyroidism (serum PTH >75pg/ml) or functional hypoparathyroidism, i.e., inappropriate normal levels of PTH (≤75pg/ml).

RESULTS

Among the 571 patients, 336 (59%) had functional hypoparathyroidism, whereas 235 (41%) had secondary hyperparathyroidism. PTH status was significantly different between sexes (p=0.003): we found functional hypoparathyroidism in 61% of women and 43% of men (secondary hyperparathyroidism in 39% of women and 57% of men). The significance of the between-sex difference was maintained after adjustment for age, estimated GFR, phosphate, albumin-adjusted total calcium, albumin, Barthel index scores, 25-hydroxyvitamin D, and hip fracture type (either cervical or trochanteric). The adjusted odds ratio was 1.85 (95%CI from 1.09 to 3.13; p=0.023).

CONCLUSIONS

Data shows that PTH response to vitamin D deficiency was sex-associated following a fracture of the hip. The higher prevalence of secondary hyperparathyroidism may play a role in the known prognostic disadvantage found in hip-fracture men.

Adherence to recommendations for fall prevention significantly affects the risk of falling after hip fracture: post-hoc analyses of a quasi-randomized controlled trial

BACKGROUND

Few studies focused on fall prevention in hip-fracture survivors.

AIM

To investigate the role of adherence to targeted recommendations on both home environment and behaviors in affecting the hazard of falling after a fall-related hip fracture.

DESIGN

Post-hoc analysis of a quasi-randomized controlled trial.

SETTING

Post-acute rehabilitation hospital.

POPULATION

Ninety-five of 119 women living in the community with a fall-related fracture of the hip.

METHODS

We assessed home hazard of falling and suggested targeted modifications of home environment and behaviors in activities of daily living to prevent falls during inpatient rehabilitation. Falls were recorded at a six-month follow-up during a pre-planned home visit.

RESULTS

Nineteen of the 95 women sustained at least one fall during the six-month follow-up. Women with > 2 uncorrected risk factors had a significantly higher risk of falling than those with 0-2 risk factors; the odds ratio adjusted for four confounders was 4.58 (95%CI 1.472-4.250; P=0.009). Adherence to recommendations for fall prevention was negatively associated with fall risk. The adjusted odds ratio for a ten percent increase in adherence rate was 0.749 (95%CI 0.594-0.945; P=0.015).

CONCLUSION

Uncorrected environmental and behavioral risk factors and poor adherence to targeted recommendations for fall prevention significantly predicted the risk of falling in community-dwelling women who sustained a fall-related hip fracture.

CLINICAL REHABILITATION IMPACT

Fall-risk assessment should be performed during inpatient rehabilitation following a fall-related hip fracture. Improving adherence to targeted recommendations emerges as a major goal to prevent falls in hip-fracture survivors.

Rehabilitation after total hip arthroplasty: a systematic review of controlled trials on physical exercise programs

Total hip arthroplasty (THA) has revolutionized the care of patients with end-stage joint disease, leading to pain relief, functional recovery, and substantial improvement in quality of life. However, long-term studies indicate persistence of impairment and functional limitation after THA, and the optimal rehabilitation protocols are largely unknown. The aim of this paper was to systematically review the controlled trials published on the effectiveness of physical exercise programs after THA. Nine studies were retrieved from MEDLINE and reviewed. Results show that the physical exercise protocols most frequently used after THA in the early postoperative phase are neither supported nor denied by clinical controlled trials. Convincing evidence for the effectiveness of single interventions in addition to usual exercise programs exists for each of the three following options: treadmill training with partial body-weight support, unilateral resistance training of the quadriceps muscle (operated side), and arm-interval exercises with an arm ergometer. In the late postoperative phase (operation interval > 8 weeks) exercise programs consistently improve both impairment and ability to function. Weight-bearing exercises with hip-abductor eccentric strengthening may be the crucial component of the late-phase protocols. Substantial limitations were found in the nine studies, including small sample size, patient selection, heterogeneity of outcome assessments, and potential sources of variability not investigated. Despite limitations, we conclude that three main suggestions emerge from controlled trials on physical exercise after THA: early postoperative protocols should include additive interventions whose effectiveness has been shown. Late postoperative programs are useful and should comprise weight-bearing exercises with hip-abductor eccentric strengthening.

Hip-fracture type does not affect the functional outcome after acute in-patient rehabilitation: a study of 684 elderly women

AIM

To investigate differences in the functional outcome between women sustaining cervical or trochanteric fractures of the hip.

METHODS

We studied 684 of 736 women admitted consecutively to a rehabilitation hospital in Italy because of their first hip fracture. Functional recovery was assessed by using Barthel index scores. Fractures were classified as either cervical (n=335) or trochanteric (n=349) on the basis of surgical and radiographic findings.

RESULTS

After acute in-patient rehabilitation, women with trochanteric fracture had a significantly lower Barthel index score than women with cervical fracture (median values were 85 and 90 respectively, interquartile ranges were 25 and 30 respectively, P=0.001). Length of stay in the hospital was significantly longer in women with trochanteric fractures (median was 37 days vs 36 days; interquartile range was 10 days vs 8 days, P=0.018). However, the differences between the two groups were no longer significant after adjustment for eight variables that affect functional ability in the same population (i.e., age, pressure ulcers, cognitive impairment, neurologic impairment, infections during the length of stay, bone mineral density, body mass index, and Barthel index scores assessed before rehabilitation). Further-more, we found no significant differences in the change of Barthel index scores during rehabilitation and in Barthel index efficiency (change in the Barthel index score after rehabilitation divided by the length of stay in hospital) between the two groups of women.

CONCLUSIONS

After adjustment for several confounders, we did not show significant differences in the functional outcome between women with cervical or trochanteric fracture of the hip.

Hyperaccumulator Alyssum murale relies on a different metal storage mechanism for cobalt than for nickel

The nickel (Ni) hyperaccumulator Alyssum murale has been developed as a commercial crop for phytoremediation/phytomining Ni from metal-enriched soils. Here, metal co-tolerance, accumulation and localization were investigated for A. murale exposed to metal co-contaminants. A. murale was irrigated with Ni-enriched nutrient solutions containing basal or elevated concentrations of cobalt (Co) or zinc (Zn). Metal localization and elemental associations were investigated in situ with synchrotron X-ray microfluorescence (SXRF) and computed-microtomography (CMT). A. murale hyperaccumulated Ni and Co (> 1000 microg g(-1) dry weight) from mixed-metal systems. Zinc was not hyperaccumulated. Elevated Co or Zn concentrations did not alter Ni accumulation or localization. SXRF images showed uniform Ni distribution in leaves and preferential localization of Co near leaf tips/margins. CMT images revealed that leaf epidermal tissue was enriched with Ni but devoid of Co, that Co was localized in the apoplasm of leaf ground tissue and that Co was sequestered on leaf surfaces near the tips/margins. Cobalt-rich mineral precipitate(s) form on leaves of Co-treated A. murale. Specialized biochemical processes linked with Ni (hyper)tolerance in A. murale do not confer (hyper)tolerance to Co. A. murale relies on a different metal storage mechanism for Co (exocellular sequestration) than for Ni (vacuolar sequestration).

Diagnostic value of prealbumin and retinol-binding protein in acute and chronic liver diseases

Prealbumin (PA) and retinol-binding protein (RBP) serum concentrations have been determined in 161 patients with different chronic and acute liver diseases and in 49 healthy controls. Their possible role in clinical practice as liver markers of hepatic biosynthesis in comparison with other traditional tests: albumin, pseudocholinesterase and clotting factors II, VII and X associated activity (Hepato-Quick) was investigated. PA and RBP were always highly intercorrelated and significantly decreased in acute viral hepatitis, steatosis, chronic persistent and active hepatitis, cirrhosis, hepatic tumors and primary biliary cirrhosis. Among the different tests, PA and RBP presented the best values of specificity (0.98 and 0.97, respectively), sensitivity (0.77 and 0.73) and positive (0.99) and negative prediction (0.57 and 0.46). In chronic liver diseases PA and RBP distinguished more efficiently than the other biosynthetic markers among diseases with different degree of severity. In acute viral hepatitis the behavior of PA and RBP, followed for 4 consecutive weeks, was similar to that of Hepato-Quick and better than the other tests in reflecting the clinical course of the disease.

[Changes in plasma lipids and lipoproteins in chronic liver diseases]

In 214 patients with different chronic liver diseases and in 31 controls the plasma lipids (total and esterified cholesterol, HDL cholesterol, triglycerides) and lipoproteins have been evaluated. The liver patients were classified not only according to traditional diagnostic criteria, but also using a functional classification based on the evaluation of biosynthetic alteration and cholestatic damage, separately assessed in all patients. Parenchimal liver diseases and cholestatic diseases show different and specific plasma lipids and lipoprotein abnormalities. In parenchimal diseases (notably cirrhosis) a reduction of the plasmatic level of total, esterified and HDL cholesterol, without significant changes of triglycerides and lipoproteins was observed. As documented by functional classification, the reduction of total and esterified cholesterol correlates significantly with the degree of biosynthetic alteration. This finding may be related to the reduced hepatic cholesterol synthesis, probably associated with a decreased serum activity of the lecithin cholesterol acyl transferase (LCAT), due to impaired hepatic enzyme synthesis.