Cellular Compartmentation of Zinc in Leaves of the Hyperaccumulator Thlaspi caerulescens1

Cellular compartmentation of Zn in the leaves of the hyperaccumulator Thlaspi caerulescens was investigated using energy-dispersive x-ray microanalysis and single-cell sap extraction. Energy-dispersive x-ray microanalysis of frozen, hydrated leaf tissues showed greatly enhanced Zn accumulation in the epidermis compared with the mesophyll cells. The relative Zn concentration in the epidermal cells correlated linearly with cell length in both young and mature leaves, suggesting that vacuolation of epidermal cells may promote the preferential Zn accumulation. The results from single-cell sap sampling showed that the Zn concentrations in the epidermal vacuolar sap were 5 to 6.5 times higher than those in the mesophyll sap and reached an average of 385 mm in plants with 20,000 μg Zn g−1 dry weight of shoots. Even when the growth medium contained no elevated Zn, preferential Zn accumulation in the epidermal vacuoles was still evident. The concentrations of K, Cl, P, and Ca in the epidermal sap generally decreased with increasing Zn. There was no evidence of association of Zn with either P or S. The present study demonstrates that Zn is sequestered in a soluble form predominantly in the epidermal vacuoles in T. caerulescens leaves and that mesophyll cells are able to tolerate up to at least 60 mm Zn in their sap.

Interisland and interarchipelago transfer of stone tools in prehistoric Polynesia.

Tracing interisland and interarchipelago movements of people and artifacts in prehistoric Polynesia has posed a challenge to archaeologists due to the lack of pottery and obsidian, two materials most readily used in studies of prehistoric trade or exchange. Here we report the application of nondestructive energy-dispersive x-ray fluorescence (EDXRF) analysis to the sourcing of Polynesian artifacts made from basalt, one of the most ubiquitous materials in Polynesian archaeological sites. We have compared excavated and surface-collected basalt adzes and adze flakes from two sites in Samoa (site AS-13-1) and the Cook Islands (site MAN-44), with source basalts from known prehistoric quarries in these archipelagoes. In both cases, we are able to demonstrate the importing of basalt adzes from Tutuila Island, a distance of 100 km to Ofu Island, and of 1600 km to Mangaia Island. These findings are of considerable significance for Polynesian prehistory, as they demonstrate the movement of objects not only between islands in the same group (where communities were culturally and linguistically related) but also between distant island groups. Further applications of EDXRF analysis should greatly aid archaeologists in their efforts to reconstruct ancient trade and exchange networks, not only in Polynesia but also in other regions where basalt was a major material for artifact production.

Avaliação de massa e rugosidade superficial de pastilhas de Ti-6Al-4V com aplicação de nanopartículas de prata submetidos ao teste de escovação

Este estudo teve por objetivo avaliar a variação da massa e rugosidade de pastilhas de Ti-6Al-4V com e sem aplicação superficial de nanopartículas de prata coloidal (BSafe®) de dimensões 1,5 cm; 0,5 cm e 0,2 cm, submetidas à teste de escovação e imersão pelo período experimental de 10 anos. No teste de escovação, quinze espécimes de Ti-6Al-4V (TE), quinze com B-Safe® (BE) e quinze de PMMA (PE) como controle foram subdivididos em três condições de escovação: dentifrício comum (DC), dentifrício experimental (DE) e controle com água destilada (H2O) por 200 mil ciclos em máquina de escovação. Os resultados foram submetidos ao teste ANOVA a 2 critérios (condição de escovação e ciclos) e teste de Tukey (α=0,05) para comparações múltiplas. Foi observada variação de massa apenas quando a condição de escovação foi DC nos espécimes do grupo PE e TE. Houve diferença estatisticamente significante nos valores da variação de rugosidade no grupo TE e PE quando a condição de escovação foi DC; no grupo BE, houve diferença quando a condição foi DC e DE, porém em DE houve redução dos valores médios. No teste de imersão, objetivando analisar a ação dos dentifrícios sem o atrito das cerdas, seis espécimes de Ti-6Al-4V (TI) e seis com B-Safe® (BI) foram subdivididos em três condições de imersão: DC, DE e H2O pelo período de 244 horas. Os resultados foram submetidos ao teste t de student pareado. Não foi observada diferença estatística entre as variações de massa e rugosidade de nenhum dos corpos de prova após o teste. Complementar aos ensaios, foi realizado um protocolo de desinfecção com terapia fotodinâmica com azul de metileno pelo período de 4 semanas nos espécimes escovados. Após todos os testes, foi realizada espectrometria de energia dispersiva de raios-X (EDS) para caracterização dos elementos químicos presentes nos espécimes, onde não se observou variações. Os resultados sugerem que o DE é mais indicado para utilização com implantes, enquanto DC apresenta um poder abrasivo capaz de danificar a superfície do Ti-6Al- 4V. Não foi observado nenhum indício de corrosão em nenhum grupo testado.

Ultrasound-assisted selective hydrogenation of C-5 acetylene alcohols with Lindlar catalysts

The selective hydrogenation of 2-methyl-3-butyn-2-ol (MBY) was performed in the presence of Lindlar catalyst, comparing conventional stirring with sonication at different frequencies of 40, 380 and 850 kHz. Under conventional stirring, the reaction rates were limited by intrinsic kinetics, while in the case of sonication, the reaction rates were 50–90% slower. However, the apparent reaction rates were found to be significantly frequency dependent with the highest rate observed at 40 kHz. The original and the recovered catalysts after the hydrogenation reaction were compared using bulk elemental analysis, powder X-ray diffraction and scanning and transmission electron microscopy coupled with energy-dispersive X-ray analysis. The studies showed that sonication led to the frequency-dependent fracturing of polycrystalline support particles with the highest impact caused by 40 kHz sonication, while monocrystals were undamaged. In contrast, the leaching of Pd/Pb particles did not depend on the frequency, which suggests that sonication removed only loosely-bound catalyst particles.

The breakdown of stainless steels in strong acids

A study was made of the corrosion behaviour in the ASTM standard Nitric acid and Oxalic acid tests, of two commercial AISI type 304L steels in the as received condition and after various heat treatments. Optical microscopy and SEM, TEM and STEM in conjunction with energy dispersive x-ray analysis, were used to correlate the corrosion behaviour of these steels with their microstructure. Some evidence of phosphorus segregation at grain boundaries was found. The corrosion behaviour at microstructural level was studied by examining on the TEM thin foils of steel that had been exposed to boiling nitric acid. Banding attack in the nitric acid and oxalic acid tests was studied using SEM and EPNA and found to be due to the micro-segregation of chromium and nickel. Using two experimental series of 304L, one a 17% Cr, 91 Ni, steel with phosphorus additions from 0.006% to 0.028%, the other a 20% Cr, 121 Ni steel with boron additions from 0.0011 to 0.00B51. The effect of these elements on corrosion in the nitric acid test was studied. The effect of different cooling rates and different solution treatment temperature on the behaviour of these steels was examined. TEM and STEM in conjunction with energy-dispersive x-ray analysis were again used to study the microstructure of the steels. Phosphorus was found to affect the corrosion behaviour but no effect was found with boron.

In vitro bioactivity of titanium-doped bioglass

Previous studies have suggested that incorporating relatively small quantities of titanium dioxide into bioactive glasses may result in an increase in bioactivity and hydroxyapatite formation. The present work therefore investigated the in vitro bioactivity of a titanium doped bioglass and compared the results with 45S5 bioglass. Apatite formation was evaluated for bioglass and Ti-bioglass in the presence and absence of foetal calf serum. Scanning electron microscopy (SEM) images were used to evaluate the surface development and energy dispersive X-ray measurements provided information on the elemental ratios. X-ray diffraction spectra confirmed the presence of apatite formation. Cell viability was assessed for bone marrow stromal cells under direct and indirect contact conditions and cell adhesion was assessed using SEM. © 2014 Springer Science+Business Media.

An experimental geochemical characterization analysis of archaeological iron from the contact period of Newfoundland and Labrador

This research uses scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX) and inductively coupled plasma-mass spectrometry (ICP-MS) on cross-sections of iron artifacts sectioned from along shafts to determine the elemental constituents of a collection of Inuit and European artifacts from along the coast of Labrador. Hand-wrought iron nails from early historic period (16th – 18th centuries CE) Inuit sites in Labrador were originally manufactured by and acquired from early whalers and fishers of various European nationalities. The purpose of this research was to assess if the elements in different samples are sufficiently homogeneous to be viable for a provenience analysis to discern which Inuit nails were originally derived from which European groups; the Basque, English or French. The consistent relationships between the geochemical signatures of iron nails found in Inuit sites and historic nails derived from specific European groups could provide insights into the prevalence, activity and the nature of indigenous interactions of different European nationalities in the region over time. The results show that the methods applied to evaluate the geochemistry of the nails was not sufficient to detect meaningful patterns because the nails did not demonstrate the necessary degree of chemical uniformity among different samples in the same artifacts.

Organometallic derivatives of cyclotriphosphazene as precursors of nanostructured metallic materials: a new solid state method

The cyclic phosphazene trimers [N3P3(OC6H5)5OC5H4N·Ti(Cp)2Cl][PF6] (3), [N3P3(OC6H4CH2CN·Ti(Cp)2Cl)6][PF6]6 (4), [N3P3(OC6H4-But)5(OC6H4CH2CN·Ti(Cp)2Cl)][PF6] (5), [N3P3(OC6H5)5C6H4CH2CN·Ru(Cp)(PPh3)2][PF6] (6), [N3P3(OC6H5)5C6H4CH2CN·Fe(Cp)(dppe)][PF6] (7) and N3P3(OC6H5)5OC5H4N·W(CO)5 (8) were prepared and characterized. As a model, the simple compounds [HOC5H5N·Ti(Cp)2Cl]PF6 (1) and [HOC6H4CH2CN·Ti(Cp)2Cl]PF6 (2) were also prepared and characterized. Pyrolysis of the organometallic cyclic trimers in air yields metallic nanostructured materials, which according to transmission and scanning electron microscopy (TEM/SEM), energy-dispersive X-ray microanalysis (EDX), and IR data, can be formulated as either a metal oxide, metal pyrophosphate or a mixture in some cases, depending on the nature and quantity of the metal, characteristics of the organic spacer and the auxiliary substituent attached to the phosphorus cycle. Atomic force microscopy (AFM) data indicate the formation of small island and striate nanostructures. A plausible formation mechanism which involves the formation of a cyclomatrix is proposed, and the pyrolysis of the organometallic cyclic phosphazene polymer as a new and general method for obtaining metallic nanostructured materials is discussed.

Room temperature ferroelectric and magnetic investigations and detailed phase analysis of Aurivillius phase Bi 5Ti 3Fe 0.7Co 0.3O 15 thin films

Aurivillius phase Bi 5Ti 3Fe 0.7Co 0.3O 15 (BTF7C3O) thin films on α-quartz substrates were fabricated by a chemical solution deposition method and the room temperature ferroelectric and magnetic properties of this candidate multiferroic were compared with those of thin films of Mn 3 substituted, Bi 5Ti 3Fe 0.7Mn 0.3O 15 (BTF7M3O). Vertical and lateral piezoresponse force microscopy (PFM) measurements of the films conclusively demonstrate that BTF7C3O and BTF7M3O thin films are piezoelectric and ferroelectric at room temperature, with the major polarization vector in the lateral plane of the films. No net magnetization was observed for the in-plane superconducting quantum interference device (SQUID) magnetometry measurements of BTF7M3O thin films. In contrast, SQUID measurements of the BTF7C3O films clearly demonstrated ferromagnetic behavior, with a remanent magnetization, B r, of 6.37 emu/cm 3 (or 804 memu/g), remanent moment 4.99 × 10 -5 emu. The BTF7C3O films were scrutinized by x-ray diffraction, high resolution transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive x-ray analysis mapping to assess the prospect of the observed multiferroic properties being intrinsic to the main phase. The results of extensive micro-structural phase analysis demonstrated that the BTF7C3O films comprised of a 3.95 Fe/Co-rich spinel phase, likely CoFe 2 - xTi xO 4, which would account for the observed magnetic moment in the films. Additionally, x-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) imaging confirmed that the majority of magnetic response arises from the Fe sites of Fe/Co-rich spinel phase inclusions. While the magnetic contribution from the main phase could not be determined by the XMCD-PEEM images, these data however imply that the Bi 5Ti 3Fe 0.7Co 0.3O 15 thin films are likely not single phase multiferroics at room temperature. The PFM results presented demonstrate that the naturally 2D nanostructured Bi 5Ti 3Fe 0.7Co 0.3O 15 phase is a novel ferroelectric and has potential commercial applications in high temperature piezoelectric and ferroelectric memory technologies. The implications for the conclusive demonstration of ferroelectric and ferromagnetic properties in single-phase materials of this type are discussed.

Site controlled red-yellow-green light emitting InGaN quantum discs on nano-tipped GaN rods

We report a method of growing site controlled InGaN multiple quantum discs (QDs) at uniform wafer scale on coalescence free ultra-high density (>80%) nanorod templates by metal organic chemical vapour deposition (MOCVD). The dislocation and coalescence free nature of the GaN space filling nanorod arrays eliminates the well-known emission problems seen in InGaN based visible light sources that these types of crystallographic defects cause. Correlative scanning transmission electron microscopy (STEM), energy-dispersive X-ray (EDX) mapping and cathodoluminescence (CL) hyperspectral imaging illustrates the controlled site selection of the red, yellow and green (RYG) emission at these nano tips. This article reveals that the nanorod tips' broad emission in the RYG visible range is in fact achieved by manipulating the InGaN QD's confinement dimensions, rather than significantly increasing the In%. This article details the easily controlled method of manipulating the QDs dimensions producing high crystal quality InGaN without complicated growth conditions needed for strain relaxation and alloy compositional changes seen for bulk planar GaN templates.

Chemical composition of manganese micronodules from expedition VA-05/1 in the Pacific Ocean

A radioisotope energy-dispersive X-ray (EDX) system has been used on board the German research vessel "Valdivia" during an exploration expedition in the northern equatorial Pacific in 1973. The instrumentation used consisted of an X-ray detection system incorporating a 30 mm2 effective-area Si (Li) detector with a measured energy resolution of 195 eV for Mn K alpha X-rays, standard nuclear electronics, a 1024-channel analyser and a data read-out unit. The X-ray spectra in the manganese-nodule samples were excited by a 30-mCi 238Pu source. The six elements Mn, Fe, Co, Ni, Cu and Zn were analysed on board. Precision values for the analyses were less than 3% for Mn, Fe, Ni, Cu and Zn and about 5% for Co. A total amount of 350 analyses was carried out during a one-month cruise. Average contents of 190 analysed whole manganese-nodule samples from all the sampling sites of the covered area were 23.3% Mn, 6.7% Fe, 0.23% Co, 1.16% Ni, 0.94% Cu and 0.10% Zn. The average content of the base metals expressed as the sum of the Co, Ni, Cu and Zn contents was 2.48%. A linear relationship between Mn and Ni in all analysed samples, including whole manganese-nodule samples, zones of manganese nodules and manganese crusts, was observed. The Mn/Ni ratio calculated by regression analysis was 23.0. Zonal variations of the chemical contents of the six elements in the manganese nodules were found. A size classification of the manganese nodules has been suggested. Geochemical correlations of Cu and Ni versus Mn/Fe in the investigated samples are given.

Effect of adding mineral additives to alkali-activated natural pozzolan paste

Natural pozzolans are raw materials from geological deposits with a range of chemical compositions that when combined with suitable alkali activators can be converted to geopolymer cement for concrete production. In this paper the concept of adding mineral additives to enhance the properties of geopolymer cement is introduced. Taftan andesite, a natural Iranian pozzolan, was used to study the effect of adding mineral additives such as kaolinite, lime and other calcined pozzolans on the compressive strength of geopolymer cement under both normal and autoclave curing. Scanning electron microscopy (SEM)/energy dispersive X-ray (EDX) was used to determine the composition of the gel phase in both alkali-activated Taftan pozzolan with and without mineral additions. The work has shown that deficiencies in SiO2, Al2O3 and CaO content in the raw natural pozzolan can be compensated for by adding mineral additives for enhanced properties.

Metallurgia del piombo e siderurgia nel sito protostorico di Brunku ’e s’Omu (Sardegna centro-occidentale): inquadramento funzionale dei manufatti e ricostruzione dei processi produttivi

The archaeological excavations carried out in 2013 in the hut n. 16 of the protohistoric settlement of Brunku ’e s’Omu (central-western Sardinia) returned some metal products. The morpho-metric and functional study of these artifacts al-lowed the identification of two mending strips and other remains related to Bronze Age (late II millennium BC) ceramic vessels reparing. Some uncertainly dated slags and metal fragments were also identified. Visual examination and archaeometric investigation carried out by means of portable energy dispersive X-ray fluores-cence spectrometry (pXRF) were performed on these metals. The analyses were able to relate some remains to iron manufacturing and highlighted the lead composition of the other ones. The chosen approach further clarified some as-pects of nuragic metallurgists’ behaviour in selecting and processing metalliferous geo-materials.

Elemental Anisotropic Growth and Atomic-Scale Structure of Shape-Controlled Octahedral Pt–Ni–Co Alloy Nanocatalysts

Multimetallic shape-controlled nanoparticles offer great opportunities to tune the activity, selectivity, and stability of electrocatalytic surface reactions. However, in many cases, our synthetic control over particle size, composition, and shape is limited requiring trial and error. Deeper atomic-scale insight in the particle formation process would enable more rational syntheses. Here we exemplify this using a family of trimetallic PtNiCo nanooctahedra obtained via a low-temperature, surfactant-free solvothermal synthesis. We analyze the competition between Ni and Co precursors under coreduction “one-step” conditions when the Ni reduction rates prevailed. To tune the Co reduction rate and final content, we develop a “two-step” route and track the evolution of the composition and morphology of the particles at the atomic scale. To achieve this, scanning transmission electron microscopy and energy dispersive X-ray elemental mapping techniques are used. We provide evidence of a heterogeneous element distribution caused by element-specific anisotropic growth and create octahedral nanoparticles with tailored atomic composition like Pt1.5M, PtM, and PtM1.5 (M = Ni + Co). These trimetallic electrocatalysts have been tested toward the oxygen reduction reaction (ORR), showing a greatly enhanced mass activity related to commercial Pt/C and less activity loss than binary PtNi and PtCo after 4000 potential cycles.