Cr cluster characterization in Cu-Cr-Zr alloy after ECAP processing and aging using SANS and HAADF-STEM

International audienceThe precipitation of nano-sized Cr clusters was investigated in a commercial Cu-1Cr-0.1Zr (wt.%) alloy processed by Equal-Channel Angular Pressing (ECAP) and subsequent aging at 550 °C for 4 hours using small angle neutron scattering (SANS) measurements and high-angle annular dark-field-scanning transmission electron microscopy (HAADF-STEM). The size and volume fraction of nano-sized Cr clusters were estimated using both techniques. These parameters assessed from SANS (d~3.2 nm, Fv~1.1 %) agreed reasonably with those from HAADF-STEM (d ~2.5 nm, Fv~2.3%). Besides nano-sized Cr clusters, HAADF-STEM technique evidenced the presence of rare cuboid and spheroid sub-micronic Cr particles about 380-620 nm mean size. Both techniques did not evidence the presence of intermetallic CuxZry phases within the aging conditions

The Recognition of N-Glycans by the Lectin ArtinM Mediates Cell Death of a Human Myeloid Leukemia Cell Line

ArtinM, a d-mannose-binding lectin from Artocarpus heterophyllus (jackfruit), interacts with N-glycosylated receptors on the surface of several cells of hematopoietic origin, triggering cell migration, degranulation, and cytokine release. Because malignant transformation is often associated with altered expression of cell surface glycans, we evaluated the interaction of ArtinM with human myelocytic leukemia cells and investigated cellular responses to lectin binding. The intensity of ArtinM binding varied across 3 leukemia cell lines: NB4>K562>U937. The binding, which was directly related to cell growth suppression, was inhibited in the presence of Manα1-3(Manα1-6)Manβ1, and was reverted in underglycosylated NB4 cells. ArtinM interaction with NB4 cells induced cell death (IC50 = 10 µg/mL), as indicated by cell surface exposure of phosphatidylserine and disruption of mitochondrial membrane potential unassociated with caspase activation or DNA fragmentation. Moreover, ArtinM treatment of NB4 cells strongly induced reactive oxygen species generation and autophagy, as indicated by the detection of acidic vesicular organelles in the treated cells. NB4 cell death was attributed to ArtinM recognition of the trimannosyl core of N-glycans containing a ß1,6-GlcNAc branch linked to α1,6-mannose. This modification correlated with higher levels of N-acetylglucosaminyltransferase V transcripts in NB4 cells than in K562 or U937 cells. Our results provide new insights into the potential of N-glycans containing a β1,6-GlcNAc branch linked to α1,6-mannose as a novel target for anti-leukemia treatment

Intervening with Urinary Tract Infections Using Anti-Adhesives Based on the Crystal Structure of the FimH–Oligomannose-3 Complex

Escherichia coli strains adhere to the normally sterile human uroepithelium using type 1 pili, that are long, hairy surface organelles exposing a mannose-binding FimH adhesin at the tip. A small percentage of adhered bacteria can successfully invade bladder cells, presumably via pathways mediated by the high-mannosylated uroplakin-Ia and alpha3beta1 integrins found throughout the uroepithelium. Invaded bacteria replicate and mature into dense, biofilm-like inclusions in preparation of fluxing and of infection of neighbouring cells, being the major cause of the troublesome recurrent urinary tract infections.We demonstrate that alpha-D-mannose based inhibitors of FimH not only block bacterial adhesion on uroepithelial cells but also antagonize invasion and biofilm formation. Heptyl alpha-D-mannose prevents binding of type 1-piliated E. coli to the human bladder cell line 5637 and reduces both adhesion and invasion of the UTI89 cystitis isolate instilled in mouse bladder via catheterization. Heptyl alpha-D-mannose also specifically inhibited biofilm formation at micromolar concentrations. The structural basis of the great inhibitory potential of alkyl and aryl alpha-D-mannosides was elucidated in the crystal structure of the FimH receptor-binding domain in complex with oligomannose-3. FimH interacts with Man alpha1,3Man beta1,4GlcNAc beta1,4GlcNAc in an extended binding site. The interactions along the alpha1,3 glycosidic bond and the first beta1,4 linkage to the chitobiose unit are conserved with those of FimH with butyl alpha-D-mannose. The strong stacking of the central mannose with the aromatic ring of Tyr48 is congruent with the high affinity found for synthetic inhibitors in which this mannose is substituted for by an aromatic group.The potential of ligand-based design of antagonists of urinary tract infections is ruled by the structural mimicry of natural epitopes and extends into blocking of bacterial invasion, intracellular growth and capacity to fluxing and of recurrence of the infection

Photometric determination of phosphate-ions concentration by Zirconium-Arsenazo I Complex

Повышение уровня питательных веществ (азота, фосфора) в природных водах является причиной эвтрофикации. Это приводит к гипоксии водоемов, отравлению воды токсинами водорослей, гибели рыб и других водных организмов. Поля стока (выщелачивание удобрений из почв) и неэффективно очищенные сточные воды являются основными источниками питательных веществ. Многие умягчители воды и стиральные порошки содержат фосфаты.Таким образом статья посвящена новому методу простого, быстрого и эффективного определения фосфатов в пробах воды, почвы и моющих средств

Мышьяксодержащие отходы водоочистки: возможные пути утилизации

Більшість сполук арсену є високотоксичними, в результаті чого потрапляння цих речовин в людський організм разом з водою чи їжею або тривалий контакт зі шкірою призводить до численних проблем зі здоров’ям (гіперкератоз, меланоз, ракові захворювання, ендокринні розлади, генотоксичні ефекти тощо), що робить видалення сполук арсену дуже важливим процесом у водоочищенні. Природні води багатьох країн та стічні води деяких підприємств містять великі концентрації сполук арсену, які в результаті процесів водоочищення переходять у різноманітні тверді та рідкі відходи (коагуляційні шлами, відпрацьовані адсорбенти, регенераційні розчини, концентрат зі стадії зворотного осмосу тощо). Зазвичай сполуки арсену іммобілізуються у вигляді нерозчинних сполук феруму в результаті перебігу коагуляції чи ряду інших процесів водоочищення. Ферум (III) арсенат та деякі інші арсенати мають набагато нижчу розчинність в лужному середовищі, тобто бажано зберігати і використовувати ці відходи разом зі сполуками, що забезпечують лужну реакцію. Одним з таких матеріалів є цемент, який характеризується високими значеннями рН, а вміст арсену в цементі не нормується, оскільки організм людини безпосередньо не контактує з цементом. Результати експериментів довели, що утилізація забруднених арсеном адсорбентів у вигляді цементних виробів є відносно безпечною за вмісту арсену 53,3-142,2 мкг/г, оскільки вимивання арсенатів не відбулося навіть за 7 днів. Відпрацьовані залізовмісні адсорбенти мають перспективи як забарвлюючі добавки бетонних виробів, оскільки навіть незначна кількість Fe2O3 надає готовим бетонним виробам приємний лососевий відтінок. Різні сполуки феруму (III) можуть надавати спектр відтінків бетонним виробам (жовтуваті, охристі, коричневі, лососеві тощо), що є перспективним в контексті виробництва тротуарної плитки, будівельних матеріалів та в деяких інших галузях.Iron (III) arsenate and some other arsenates have a much lower solubility in an alkaline environment, that is, it is advisable to store and use these wastes together with compounds that provide an alkaline reaction. Cement is characterized by high pH values, and the content of arsenic in cement is not normalized, because the human body does not directly contact with cement. The experimental results proved that utilization of arsenic-containing adsorbents in the form of concrete products was safe in case of arsenic content from 53.3-142.2 μg/g and had perspectives in colouring of concrete products.Арсенат железа (III) и некоторые другие арсенаты имеют гораздо более низкую растворимость в щелочной среде, то есть желательно хранить и использовать эти отходы вместе с соединениями, обеспечивающими щелочную реакцию. Цемент характеризуется высокими значениями рН, а содержание мышьяка в цементе не нормируется, поскольку организм человека напрямую не контактирует с цементом. Результаты экспериментов доказали, что утилизация мышьяксодержащих адсорбентов в виде цементных изделий является безопасным при содержании мышьяка 53,3-142,2 мкг/г и имеет перспективы в окрашивании бетонных изделий

Morphology and chemical composition of Cu/Sn/Cu and Cu(5 at-%Ni)/Sn/Cu(5 at-%Ni) interconnections

In the present paper, scanning and transmission electron microscopies as well as energy dispersive X-ray spectroscopy investigations were performed to describe the morphology and chemical composition of the intermetallic phases growing in Cu/Sn/Cu and Cu(Ni)/Sn/Cu(Ni) interconnections during the diffusion soldering process. The obtained results revealed that even a small amount of Ni addition (5 at-%) to the Cu substrate totally changes the morphology and the rate of formation of the intermetallic phase layers in the solder/substrate reaction zone of the interconnections prepared at the same time and joining temperature conditions. The presented studies are promising in terms of the shortening of the soldering time in the elecronic industry

Characteristics of intermetallic phases in Cu/(Sn,Ni) diffusion couples annealed at 220 °C

The influence of Ni addition (5 at.%) on the morphology and chemical composition of the phases formedduring solid state reaction in Cu/(Sn,Ni) diffusion couples, annealed at 220 C for different periods oftime, was investigated. Chemical analysis of the reaction zone performed using scanning electron microscopy(SEM/EDS) identified several intermetallic phases. Near to the copper substrate, a thin andcontinuous layer of the Cu$_3$Sn phase was observed. Moving towards the (Sn,Ni) end of the diffusioncouple, the (Cu$_{1x}$Ni$_x$)$_6$Sn$_5$ phase was identified. This phase was represented by two types of structures: adiscontinuous layer located close to the Cu$_3$Sn phase, and precipitates (needles or faced) within the(Sn,Ni) end. These structures of (Cu$_{1x}$Ni$_x$)$_6$Sn$_5$ also varied in chemical composition. The experiment withsynchrotron radiation demonstrated two crystallographic variants of the Cu$_6$Sn$_5$ phase: hightemperaturehexagonal $\eta$ and low-temperature monoclinic $\eta'$; however, only the hexagonal variantwas confirmed by TEM. Differences in the morphology and chemical composition of the (Cu$_{1x}$Ni$_x$)$_6$Sn$_5$ phase were attributed to various mechanisms of their formation. The precipitates with a higher contentof Ni were most probably transformed from the Ni$_3$Sn$_4$ phase present in the initial (Ni,Sn) end-member,while the formation of the Ni-poor layer took place as a result of diffusion at the initial interface. Afterthe annealing experiment, the (Ni$_{1x}$Cu$_x$)$_3$Sn$_4$ phase was observed beyond the interface area as small, irregularly distributed precipitates in the (Sn,Ni) end-member. TEM examination allowed for the precisephase characterisation of the mentioned intermetallics. Moreover, except for the strong reflectionsvisible in SADP fitted to the hexagonal $\eta$-Cu$_6$Sn$_5$ phase, additional reflections were observed andassigned to the cubic Cu$_9$NiSn$_3$ phase