As a toxic metal, cadmium (Cd) affects microbial and plant metabolic processes, thereby potentially reducing the efficiency of microbe or plant-mediated remediation of Cd-polluted soil. The role of ...siderophores produced by Streptomyces tendae F4 in the uptake of Cd by bacteria and plant was investigated to gain insight into the influence of siderophores on Cd availability to micro-organisms and plants. The bacterium was cultured under siderophore-inducing conditions in the presence of Cd. The kinetics of siderophore production and identification of the siderophores and their metal-bound forms were performed using electrospray ionization mass spectrometry. Inductively coupled plasma spectroscopy was used to measure iron (Fe) and Cd contents in the bacterium and in sunflower plant grown in Cd-amended soil. Siderophores significantly reduced the Cd uptake by the bacterium, while supplying it with iron. Bacterial culture filtrates containing three hydroxamate siderophores secreted by S. tendae F4 significantly promoted plant growth and enhanced uptake of Cd and Fe by the plant, relative to the control. Furthermore, application of siderophores caused slightly more Cd, but similar Fe uptake, compared with EDTA. Bioinoculation with Streptomyces caused a dramatic increase in plant Fe content, but resulted only in slight increase in plant Cd content. It is concluded that siderophores can help reduce toxic metal uptake in bacteria, while simultaneously facilitating the uptake of such metals by plants. Also, EDTA is not superior to hydroxamate siderophores in terms of metal solubilization for plant uptake. The study showed that microbial processes could indirectly influence the availability and amount of toxic metals taken up from the rhizosphere of plants. Furthermore, although EDTA is used for chelator-enhanced phytoremediation, microbial siderophores would be ideal for this purpose.
Microscale Thermoelectric Generators (microTEGs) have a high application potential for energy harvesting for autonomous microsystems. In contrast to conventional thermoelectric generators, microTEGs ...can only supply small output-voltages. Therefore, voltage converters are required to provide supply-voltages that are sufficiently high to power microelectronics. However, for high conversion efficiency, voltage converters need to be optimized for the limited input voltage range and the typically high internal resistance of microTEGs. To overcome the limitations of conventional voltage converters we present an optimized self-startup voltage converter with dynamic maximum power point tracking. The performance potential of our concept is theoretically and experimentally analyzed. The voltage conversion interface demonstrates energy harvesting from open-circuit voltages as low as 30.7 mV, and enables independent and full start-up from 131 mV. No additional external power supply is required at any time during operation. It can be operated with a wide range of internal resistances from 20.6 to − 4 kΩ with a conversation efficiency between
η
= 68–79%.
CONTEXT Physical abuse is a leading cause of serious head injury and death in
children aged 2 years or younger. The incidence of inflicted traumatic brain
injury (TBI) in US children is unknown. ...OBJECTIVE To determine the incidence of serious or fatal inflicted TBI in a defined
US population of approximately 230 000 children aged 2 years or younger. DESIGN, SETTING, AND SUBJECTS All North Carolina children aged 2 years or younger who were admitted
to a pediatric intensive care unit or who died with a TBI in 2000 and 2001
were identified prospectively. Injuries were considered inflicted if accompanied
by a confession or a medical and social service agency determination of abuse. MAIN OUTCOME MEASURE Incidence of inflicted TBI. Multivariate logistic regression models
were used to compare children with inflicted injuries with those with noninflicted
injuries and with the general state population aged 2 years or younger. RESULTS A total of 152 cases of serious or fatal TBI were identified, with 80
(53%) incurring inflicted TBI. The incidence of inflicted traumatic brain
injury in the first 2 years of life was 17.0 (95% confidence interval CI,
13.3-20.7) per 100 000 person-years. Infants had a higher incidence than
children in the second year of life (29.7 95% CI, 22.9-36.7 vs 3.8 95%
CI, 1.3-6.4 per 100 000 person-years). Boys had a higher incidence than
girls (21.0 95% CI, 15.1-26.6 vs 13.0 95% CI, 8.4-17.7 per 100 000
person-years). Relative to the general population, children who incurred an
increased risk of inflicted injury were born to young mothers (≤21 years),
non–European American, or products of multiple births. CONCLUSIONS In this population of North Carolina children, the incidence of inflicted
TBI varied by characteristics of the injured children and their mothers. These
data may be helpful for informing preventive interventions.
P- and n-doped bismuth telluride (Bi2Te3) polycrystalline nanostructures were prepared on structured PECVD-oxide-layers using magnetron sputtering and a lithography independent deposition and ...back-etching step. The resulting polycrystalline spacer-structures have adjustable dimensions with heights of 350 to 450 nm, a widths of 200 to 220 nm and a fix length of 1240 μm and 4020 μm. This paper presents the production of Bi2Te3 structures and how annealing affects the electrical conductivity in order to improve their potential in thermoelectric applications. In addition to temperature variation and multiple annealing the influence of different atmospheres during the annealing step has been investigated. It is shown that the electrical conductivity of the p-doped material increases by a factor of 1.8, while it decreases for the n-doped material.
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•Lithography idependent deposition and back-etching process for Bi2Te3 structures•Anisotropic dry etching of Bi2Te3 using argon plasma•Increase in electrical conductivity due to annealing for p-type Bi2Te3•Decrease in electrical conductivity due to annealing for n-type Bi2Te3•Oxidation of Bi2Te3 during a resist stripping step in O2-atmosphere
The remediation of large heavy metal/radionuclide (HM/R) contaminated areas by conventional remediation technologies is often too expensive. Phytoremediation can be an alternative for such areas with ...slight contaminations, and represents a convenient and sustainable method of remediation. Field site phytoremediation experiments were carried out at a former uranium mining area in East Germany. The test field site is slightly to moderately contaminated with HM/R; the phytoremediation was performed by combination of phytostabilization and phytoextraction methods combining microbial, soil and plant techniques both at field- and lab scale. Plant experiments with Triticale, Helianthus annuus and Brassica juncea were performed to investigate the influence of biological additives (fungi, bacteria) and soil amendment strategies (increasing pH and organic matter, fertilizing) on biomass production and plant tolerance to heavy metals. In lysimeter experiments, a minimization of HM/R accumulation in soil could be shown, and groundwater contamination as well as seepage water rate and load could be reduced. The final utilization of HM/R loaded plant residues after harvests was studied by biogas and ethanolic fermentations and by combustion of the plant material. The fate of HM/R in the different by-products was investigated. Finally, concepts were developed for the utilization of the HM/R loaded plant residues.
► Field site studies for phytoremediation at a uranium contaminated site were performed. ► Combination of phytostabilization and phytoextraction methods ► Different soil additives improve plant growth and soil quality. ► Utilization of metal loaded plants after harvest for the winning of energy (bioethanol, biogas, thermal energy)
The "dirty dozen" was the name used by several teachers to refer to a clique of junior high school girls who were both mean and popular. In this school, the students used the term mean as a largely ...undifferentiated characterization for acts of commission and omission whose intent, or result, was to hurt someone emotionally. This article proposes that exploring the meaning of meanness is a starting point for understanding the connections between female competition, conflict, and popularity. An examination of these connections in the context of a clique of popular girls allows for a better understanding of the sociocultural construction of meanness in junior high school.
Distribution and behavior of contaminants in plants are of increasing interest both for food production and phytoremediation. Elements like Cd, Cr, Cu, Mn, Ni, and Zn are in the focus of ...investigations, due to their nutritive function, but also potential toxicity for plants and human. Laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) was tested and a method developed to determine the spatial distribution and contents of macro and micro elements (Ca, Cd, Ce, Cr, Cu, Fe, K, La, Mn, Ni, P, S, and Zn) in leaves of sunflower (Helianthus annuus). The leaves were scanned in lines orthogonal to the leaf veins with a focused Nd:YAG-laser. The ion intensities of 13C+(internal standard), 31P+, 33S+, 39K+, 44Ca+, 52Cr+, 55Mn+, 56Fe+, 60Ni+, 63Cu+, 66Zn+, 111Cd+, 139La+, and 140Ce+ were measured with ICP-Quadrupole-MS. The standard reference material CTA-VTL-2 Virginia tobacco leaves was used for calibration. The precision and accuracy of the data were proven by determining the contents in standard reference materials IAEA-V-10 Hay, IAEA-359 Cabbage, NIST 1572 Citrus leaves, and NIST 1575 Pine needles. The robustness was tested by ablating CTA-VTL-2 while varying beam size, repetition rate, energy output, and transport gas flow rate according to a 24−1 fractional factorial design of experiments (DOE). The depth of the ablation craters was measured with Vertical Scanning Interferometry (VSI) and found to be about 30μm, regardless of the ablation of veins or mesophyll tissue of the leaf. With an in-house MATLAB® script quantitative imaging of the elemental distribution was possible. The different distribution patterns could be separated in four main groups: 1. Cd, Ce, Cu, La, Mn, and Zn accumulate at the veins of the leaves, 2. Fe and S accumulated with higher contents at the tip of the leaf, 3. K and Ni are enriched preferentially in the mesophyll, and 4. Ca, Cr, and P show homogeneous distributions over the whole leaf.
► Quantitative mapping of 13 macro and micro elements in leaves of sunflower Helianthus annuus with LA–ICP–MS. ► Distribution patterns give hints on binding and interaction of nutrients and toxic elements. ► Investigation of the laser ablation craters with Vertical Scanning Interferometry (VSI). ► Similar ablation behavior of mesophyll and leaf veins.
Extensive uranium mining in the former German Democratic Republic (GDR) in eastern Thuringia and Saxony took place during the period of 1946–1990. During mining activities, pelitic sediments rich in ...organic carbon and uranium were processed and exposed to oxygen. Subsequent pyrite oxidation and acidic leaching lead to partial contamination of the area with heavy metals and acid mine drainage (AMD) even few years after completion of remediation. One of those areas is the former heap Gessen (Ronneburg, Germany) were the residual contamination can be found 10 m under the base of the former heap containing partly permeable drainage channels. Actually, in such a system, a rapid but locally restricted mineralization of Mn oxides takes place under acidic conditions. This formation can be classified as a natural attenuation process as certain heavy metals, e.g., Cd (up to 6 μg/g), Ni (up to 311 μg/g), Co (up to 133 μg/g), and Zn (up to 104 μg/g) are bound to this phases. The secondary minerals occur as colored layers close to the shallow aquifer in glacial sediments and could be identified as birnessite and todorokite as Mn phase. The thermodynamic model shows that even small changes in the system are sufficient to shift either the pH or the Eh in the direction of stable Mn oxide phases in this acidic system. As a consequence of 9–15-year-long formation process (or even less), the supergene mineralization provides a cost-efficient contribution for remediation (natural attenuation) strategies of residual with heavy metals (e.g., Cd, Co, Ni, Zn) contaminated substrates.
Methods permitting to test the influence of the matrix as well as of its local and temporal distribution on the plasma conditions in laser ablation-inductively coupled plasma mass spectrometry ...(LA-ICP-MS) are developed. For this purpose, the MS interface is used as plasma probe allowing to investigate the average plasma condition within the ICP zone observed in terms of temporal and spatial distribution of the matrix.
Inserted matrix particles, particularly when being atomized and ionized, can cause considerable changes in both electron density and plasma temperature thus influencing the ionization equilibrium of the individual analytes. In this context, the plasma probe covers a region of the plasma for which no local thermodynamic equilibrium can be assumed. The differences in temperature, identified within the region of the plasma observed, amounted up to 3000
K. While in the central region conditions were detected that would not allow efficient atomization and ionization of the matrix, these conditions improve considerably towards the margin of the area observed. Depending on the nature as well as on the temporally and locally variable density of the matrix, this can lead to varying intensity ratios of the analytes and explain fractionation effects. By means of a derived equation it is shown that the deviation of the intensity ratio from the concentration ratio turns out to be more serious the higher the difference of the ionization potential of the analytes observed, the lower the plasma temperature and the higher the matrix concentration within the area observed.
The Rotliegend saline lake periodically covered wide areas of the Southern Permian Basin in Northwest Europe during the Permian. The sedimentology, mineralogy and geochemistry of lake deposits were ...studied to document very high frequency lake level fluctuations and to evaluate their triggers. Increased precipitation and marine ingressions into the basin resulted in lake extension. Increased run-off is documented by intercalated fluvial deposits in low-salinity deposits of the lake. Because lake deposits reflect mainly deposition in relatively wet climate phases, they are not correlatable to halite deposits in other basin areas. Decreased precipitation is followed by shrinkage of the lake, desiccation at its margins, and higher lake salinity due to concentration of the brine. Carbonate and anhydrite contents of lake deposits increased considerably before the areas fell dry, but halite is not preserved in the study area. Falling lake level is also reflected by the occurrence of wave ripples, reflecting decreased water depth and finally by desiccation and formation of evaporite crusts. Not only the mineralogical content, but also the colour of lake claystones changes with varying salinity. Anhydrite- and carbonate-free red claystones were replaced by violet to green and grey anhydritic and calcareous claystone or marls with increasing salinity. The amount of boron adsorbed on illite also corresponds to changes in salinity and can therefore be used as a palaeosalinity indicator. Rare earth element concentrations within lake deposits do not reflect variations in salinity but different palaeogeographical settings. Marine ingressions into the lake are neither reflected by the amount of boron adsorbed onto illite nor by rare earth element contents of the lake deposits. Highly saline deposits are partly characterised by intensive deformation, which can be interpreted as seismites or dissolution breccias.
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