Cleavage Zones Research Articles

Evaluation of Solidification and Interfacial Reaction of Sn-Bi and Sn-Bi-In Solder Alloys in Copper and Nickel Interfaces

Although there are studies devoted to lower Indium (In) addition, Sn-Bi alloys containing 10 wt.% In or more have been barely investigated so far. Higher In contents may offer the potential for improved joint production, better control over the growth of interfacial layers, and enhanced mechanical strength. The present article focuses on the solidification, wettability, adhesion strength, and interfacial intermetallic growth in the Sn-40%Bi-10%In alloy soldered on Cu and Ni pads. SEM-EDS, wettability tests, and tensile tests were performed. The contact angles were measured in Cu and Ni as 24° and 26°, respectively. Indium addition promoted coarsening of the as-solidified microstructure due to an increase in the alloy solidification range. The Bi spacing was increased at least three times, with a strong segregation of Bi towards the interface. The formation and growth of alloy/Cu reaction layers were also evaluated under the different aging conditions of the as-soldered joints, simulating real service. A growth kinetics model of the reaction layer showed that In increases the activation energy, thereby reducing the layer growth. The adhesions of the formed intermetallics films in Cu and Ni were analyzed using tensile tests. It was observed that the alloy/Ni couple exhibited better adhesion. Premature fracturing appears to happen in the alloy/Cu joint due to the higher intermetallic compound’s (IMC) thickness, rough morphology, and coarser microstructure. Both ductile fracture features with dimples and cleavage zones associated with Bi, Cu6(Sn,In)5, and Ni3Sn4 intermetallics were observed.

Hybrid Augmentation Mastopexy with New Generation of Smooth Surface Implants: Combining the Benefits of Fat Grafting, Inferior Muscle Support, and an L-Shaped Scar.

Augmentation mastopexy (AM) is a challenging procedure. Complications include implant displacement and visibility, which can be addressed, but the stability of the smooth implant surface and poor soft-tissue coverage may present limitations. This article describes a surgical technique for AM using a composite reverse inferior muscle sling associated with autogenous fat grafting. Forty-five patients (90 breasts; mean age, 37.7 ± 7.2 years) underwent hybrid composite reverse inferior muscular sling AM. An upper/medial pole area between the implant and the clavicle region and parasternal area was marked to receive fat grafting and divided into three zones. Three-dimensional imaging was used to evaluate lower pole stretch and intermammary distance. The average implant volume was 265 cc (range, 175 to 335 cc). The average fat volumes in zones I/II and III were 80.1 (range, 61.6 to 95.2 cc) and 39.3 (range, 25.2 to 47.3 cc), respectively. Five complications were observed in three patients (6.6%)-minor dehiscence in two (4.4%) and nipple-areola asymmetry in one (2.2%). The lower pole stretched 11.51% (9.9 mm) and 9.8% (8.5 mm) on the right and left sides, respectively ( P < 0.0001), between 10 days and 1 year postoperatively. The intermammary distance was reduced, on average, 49.9% (25.1 mm) ( P < 0.001) between the preoperative value and 1 year postoperatively. Hybrid composite reverse inferior muscular sling has led to improved aesthetic results for patients with breast ptosis and poor tissue coverage. Fat grafting and recognizing cleavage zones are still important to obtain satisfactory results. This procedure offers a good alternative for AM candidates, providing an adequate smooth surface for implant stabilization.

Reconstruction of petrophysical zoning of the Blagodatnoye gold deposit in the Yenisei Ridge: Geodynamic and physical-chemical aspect

Research subject. Petrophysical zoning of the Blagodatnoye gold-sulfide deposit in the Yenisei Ridge. Aim. To determine indicative petrophysical characteristics of the products of the main occurrence stages and to develop an evolutionary petrophysical model of the investigated deposit.Materials and methods. Physical fields were studied by the methods of magnetic and electrical exploration and gamma-spectrometry. The petromagnetic heterogeneity and mineralogical-geo chemical features of formation of polymetamorphic complexes, metasomatites and ores were studied by a neutron activation analysis of the content of rare earth and radioactive elements, petrochemical x-ray fluorescence analysis, as well as by an electron-probe microanalysis of pyrite.Results. The syncollisional fold-overthrust fault (785 Ma) of the preparatory stage provided structural control over the ore-bearing mineral-forming system. The signs of zone dislocation metamorphism include geophysical anomalies: magnetic and natural electrical anomalies due to pyrrhotite and graphite mineralization of cleavage zones on fold limbs, and specific electrical resistance from silicification zones in fold hinges. The metasomatism of the pre-ore (753 Ma) and ore (698 Ma) stages took place under rifting conditions. Pre-ore quartz-muscovite and chlorite metasomatites with carbon mineralization and supra-background Au concentrations were formed under the action of reducing reaction solutions; they remained unaltered in the non-productive part of the deposit. These formations are characterized by elevated concentrations of radioactive elements and natural electrochemical polarizability. During the ore stage, Au was concentrated by fluids with hydro-carbonate-sulfide composition under the violation of the strike-slip kinematics, which caused significant petrophysical transformations of the productive part of the deposit. Early carbon metasomatites in the sub-ore and root sections of the ore bodies were depleted in terms of U, at the same time as retaining their electrochemical activity. Uranium accumulated in the upper horizons of the productive part, whose rocks lost their polarizability due to scattered carbonate mineralization. Magnetic pyrrhotite crystallized as part of sulfides with a regular increase in its proportion in the root sections of the ore bodies. At the final stage (368 Ma), the mineralized zone was broken into a series of blocks with unequal vertical displacements and levels of erosional truncation by upcasts. This led to the exposure of various-depth sections with contrast petrophysical characteristics.Conclusions. The Blagodatnoye deposit was formed in four stages: preparatory, two ore-generating and final. The petrophysical features of the products of each stage formed the basis for the developed evolutionary petrophysical model, which will be tested on the materials of geophysical studies of the Yenisei Ridge territories.

Каменная индустрия памятника Гвоздевка i

The article covers the exploration of the stone industry of a Mesolithic site Gvozdevka I. The Stone Age man site is located in Moskalenki district of Omsk region, at the southern end of Lake Ebeyty, on the eastern bank of flood plain Amre (Amrinsky beam). It was discovered in 1976, last investigated in 2004. In the course of archaeological work, a representative collection of stone artefacts was formed, among them microplates occupying a considerable place. The manufacturing specificity of site materials is difficult for analysis, but certain aspects of plate production and utilisation can be taken into consideration. The techno-typological method, as part of attributive approach, was used for their analysis. The description and analysis of the stone industry was made according to the parameters characterising the metric indicators of cleavage, cleavage zone and dorsal surface. The basic strategy of stone cleavage is reconstructed, aimed to produce lamellar chipping with the use of pressure flaking technique. The production of inlay blanks - thin plates with straight lateral profile and sharp longitudinal edges - appears to have been the ultimate goal of the cleavage. The quality of the analysed material enables one to study not only the techno-typological aspects of its manufacture, but also the traces of non-utilisation wear, secondary processing of blanks as well as functional wear (which is the subject of further research). This suggests that the monument was used to split pre-nuclei or nuclei brought by people; the obtained plates were actively used in the process of treatment of various materials. On the whole, using the attributive approach to the study of Gvozdevka I site stone industry made it possible to establish the major strategies of stone splitting and to reconstruct the primary splitting system, as well as to create a framework for comparison with other monuments of the same period on the territory of Omsk region and adjacent areas, to outline the prospects for further research.

Influence of Hydrogenation on the Character of Fracture of Nitinol Alloy in Tension

We establish the macro- and microfractographic features of the tensile fracture of cylindrical specimens made of nitinol (Ni–Ti alloy) at room temperature and at 0°C caused by their preliminary electrolytic hydrogenation. The revealed hydrogen embrittlement of the metal was associated with the facilitation of martensite transformation, which is more clearly pronounced at the lower testing temperature. This explains the phenomenon of reorientation of the macroscopic fracture surfaces of specimens from the tensile mode into the shear mode under the influence of the conditions of embrittlement. On the microlevel, the appearance of brittle cleavages along the boundaries of martensite crystals is regarded as a specific feature of the fracture of nitinol caused by its hydrogenation. Under more severe hydrogenation conditions, the width of the cleavage zone in the subsurface layers of the specimens increases, which is explained by the deeper penetration of hydrogen into the metal favorable for the structural and phase transformations.

Методические аспекты прогноза и поисков крупнообъемных золоторудных месторождений на примере Енисейского кряжа

Актуальность исследования обусловлена необходимостью изучения и вовлечения в производство новых крупнообъемных золоторудных месторождений, что будет способствовать образованию и долгосрочному развитию целых регионов РФ. Важным аспектом является разработка новых и совершенствование существующих методов поисков золоторудных месторождений. Целью исследования является апробация методики поисков золоторудных месторождений в сложных горно-таежных ландшафтах применительно к условиям Енисейского кряжа, в частности, в пределах малоизученной восточной части этого региона, а также выделение прогнозно-поисковых критериев и признаков вновь выявленного рудопроявления Буреминское и их сопоставление с критериями и признаками известного крупнообъемного золото-сульфидного Олимпиаднинского месторождения. Методы исследования: анализ литературных и фондовых данных; прогнозные построения на предмет выделения перспективных поисковых участков на выявление крупнообъемного золотого оруденения; разработка новых и совершенствование существующих методов и методических приемов поисков золоторудных месторождений; применение этих методов (литохимическое опробование по вторичным ореолам рассеяния разных уровней разреза элювиально-делювиальных отложений, шлиховое и сколковое (точечное) опробование) на практике; лабораторно-аналитические исследования - полуколичественный спектральный анализ на 26 элементов, химико-спектральный анализ на золото. Результаты. Вновь выявлена рудоконтролирующая зона складчато-разрывных деформаций рудопроявления Буреминское, приуроченная к зоне разрывных нарушений северо-северо-западной ориентировки, оперяющих к Ишимбинской системе разломов, в узле их сочленения с разрывами СВ направления. Комплекс шлихового и литохимического по вторичным ореолам рассеяния опробования надкоренного информативного малосмещенного горизонта элювиально-делювиальных отложений позволил выявить в пределах зоны рассланцевания несколько золотоносных минерализованных зон. Последние представляют собой зоны-залежи рассеянной вкрапленной золото-сульфидной минерализации, локализованные в интенсивно железо-магнезиально-карбонатизированных углеродсодержащих карбонат-кварц-серицитовых сланцах удерейской свиты сухопитской серии среднего рифея. Для золотой минерализации рудопроявления Буреминское выделены прогнозно-поисковые критерии и признаки. По ряду из них наиболее близким аналогом рудопроявления являются первичные вкрапленные золото-сульфидные руды Олимпиаднинского месторождения, с которым проведено сопоставление основных геологических элементов рудопроявления Буреминское.

Estimation of the Deformation Value in Terrigenous Rocks by the Random Cross-Section Method (Belaya River, Northern Slope of the Greater Caucasus)

The deformation value in the Lower and Middle Jurassic terrigenous rocks from the valley of the Belaya River (the northern slope of the Greater Caucasus) is quantified by the morpholology of the cleavage zones. The numeral determination of the axis ratios of the deformation ellipses by the Fry method is performed as well. It is shown that for a statistical sample of the random cross-sections of the thin sections in the terrigenous rocks with cleavage structure the deformation value can be estimated correctly. The method of random cross-sections described in this work can be used for the quantitative estimation of deformation in nonoriented samples of terrigenous rocks.

Effect of thermal ageing on microstructure, tensile and impact properties of reduced activated ferritic-martensitic steel

Effects of thermal ageing on tensile and impact properties of India-specific Reduced Activated Ferritic-Martensitic (INRAFM) steel (9Cr-1.4W-0.06Ta-0.22V) have been studied by correlating with microstructure. The tempered martensitic steel received in the normalized and tempered (N&T) condition was thermally aged at 873K for 5000h. Thermal ageing was found to decrease hardness and tensile strength and the decrease was accompanied with increase in ductility. The steel displayed plateaus/humps in the temperature variation of yield stress and ultimate tensile strength and dip in ductility over the range 473–673K, which is considered due to the occurrence of dynamic strain ageing (DSA). The prevalence of DSA activity was found more on thermal ageing. Increase in ductile to brittle transition temperature (DBTT) and decrease in upper shelf energy (USE) of the steel were observed on thermal ageing. Detailed microscopic investigation of the steel revealed coarsening of martensitic sub-boundaries and M23C6 carbides along with the precipitation of Laves phase on thermal ageing. Coarsening of microstructural features on thermal ageing is considered to influence the reduction in strength and USE of the steel; whereas coarsening of M23C6 and precipitation of Laves phase is considered to cause the increase in DBTT. SEM fractographic study of the impact specimens revealed three distinct zones as shear lip, fibrous dimple and cleavage in an ordered away from the notch tip. With decrease in test temperature, the widths of the shear lip and fibrous dimple zones deceased whereas width of the cleavage zone increased progressively. Thermal ageing increased the widths of the shear lip and fibrous dimple zones and decreased the cleavage zone in the N&T steel at relatively higher temperatures but at lower test temperatures cleavage zone became more predominant. TEM study of the specimens extracted from the impact fractured samples at the vicinity of fracture surface, revealed substantial activity of dislocations manifested as dislocation debris in N&T steel even for impact testing at −80°C against individual dislocations for the aged steel, implying enhancement of DBTT on thermal ageing.

The mineralogical, isotope (K–Ar), structural, and textural features of the Jurassic siliciclastic complex in various tectonic environments (Greater Caucasus, Chechnya, and Georgia)

The variations in the structural, textural, mineralogical, and geochemical (isotope) features of Lower to Middle Jurassic siliciclastic sediments along the Chanty-Argun River in Mountainous Chechnya and Georgia are discussed. This profile transects areas with various types of deformed sediments, from the northern comparatively weakly deformed and altered zone, to the southern zone of intense deformation and cleavage. Southward along the profile, these alterations are accompanied by the evolution of clay mineral assemblages, as well as polytypic modifications of micas and their crystallinity index. Increasing intensity of rock alteration and cleavage leads to a change of the K–Ar system, which results in a substantially rejuvenated isotope age of the sediments with a simultaneous increase of their stratigraphic age.

Development of Custom 465® Corrosion-Resisting Steel for Landing Gear Applications

Existing high-strength low-alloy steels have been in place on landing gear for many years owing to their superior strength and cost performance. However, there have been major advances in improving the strength of high-performance corrosion-resisting steels. These materials have superior environmental robustness and remove the need for harmful protective coatings such as chromates and cadmium now on the list for removal under REACH legislation. A UK government-funded collaborative project is underway targeting a refined specification Custom 465® precipitation hardened stainless steel to replace the current material on Airbus A320 family aircraft main landing gear, a main fitting component developed by Messier-Bugatti-Dowty. This is a collaborative project between Airbus, Messier-Bugatti-Dowty, and Carpenter Technology Corporation. An extensive series of coupon tests on four production Heats of the material have been conducted, to obtain a full range of mechanical, fatigue, and corrosion properties. Custom 465® is an excellent replacement to the current material, with comparable tensile strength and fracture toughness, better ductility, and very good general corrosion and stress corrosion cracking resistance. Fatigue performance is the only significant area of deficit with respect to incumbent materials, fatigue initiation being often related to carbo-titanium-nitride particles and cleavage zones.

Mineralogical, isotopic (K-Ar) and structural-textural characteristics of the Jurassic terrigenous complex in different paleotectonic settings (Greater Caucasus, Chechnya - Georgia)

The variations in structural, textural, mineralogical and geochemical (radiometric) characteristics in the lower to middle Jurassic siliciclastic sediments of the transect across Chanty-Argun R., Mountain Chechnya and Georgia are considered. This transect crosses areas of different types of deformations from northern zone of weak deformation to southern zone of intensive deformation and cleavage. The southward change in clay mineral associations, polytypical modifications of mica minerals, their crystallinity index, a.o. are observed along the transect. The increase of intensity of secondary alternations of the rocks and dimensions of cleavage enabled the change in K-Ar-system. This is resulted in significantly younger values of measured radiologic age corresponding to older stratigraphic age.

In vivo confocal microscopy of mucous membrane pemphigoid, a new tool for the diagnosis. Reporting 6 cases

AbstractPurpose Mucous membrane pemphigoid (MMP), previously known as cicatricial pemphigoid, is an autoimmune disease characterized by linear deposition of IgG and IgA along the epithelial basement membrane zone in direct immunofluorescence (DIF). DIF requires mucosal biopsy, which can worsen the condition by triggering an inflammatory response of the mucosa, especially the conjunctiva. We assess in vivo confocal microscopy (IVCM) for the detection of the pathognomonic basement membrane cleavage zone (BMCZ) in MMPMethods Six patients (4 M, 2 W), suffering from ocular and/or oral MMP were tested with IVCM, using the handheld Vivascope 3000. Three patients had ocular involvement, 2 oral involvement, and 1 had both.Results Mean age was 76 years old. Out of the 4 patients with ocular involvement, 2 patients had active conjunctivitis and 2 patients had cicatricial lesions. A BMCZ was identified in both patients with active conjunctivitis, while none was observed in those with cicatricial lesions. All 3 patients with oral involvement had desquamative gingivitis with marked BMCZ.Conclusion IVCM is non‐invasive and reliable for the diagnosis of MMP. Conjunctival fornix biopsy is at high risk of symblepharon. These biopsies are often performed blindly as the pathological zones are barely visible clinically. IVCM enables the observation of the whole inflammatory surface of the conjunctiva and gum. To our knowledge, these are the first 2 cases of patients with conjunctival BMCZ clearly identified with IVCM.

Nanoscale Fracture Morphologies of Soft Magnetic CoFeTaB Amorphous Alloy

We analyzed the failure characteristics of the bulk metallic glass Co43Fe20Ta5.5B31.5 (at.%) deformed by compression and by bending of the ribbons. Under the load the amorphous structure can store high elastic energy. The surface morphology of nanoscale fracture is in accord with the micromechanisms of the failure of the amorphous structure. The fracture surface consists of a smooth mirror cleavage zone and a river pattern zone with nanosized dimples, arranged in lines respecting the periodic corrugation zones, oriented perpendicular to the crack propagation direction. The presence of the failure initiation centers in the ribbon in uences the dynamics of crack propagation and also the surface morphology of the fracture.

The geology of the carbonate-hosted Blende Ag–Pb–Zn deposit, Wernecke Mountains, Yukon, Canada

The Ag–Zn–Pb Blende deposit is located in the Wernecke Mountains, Yukon and is hosted by the middle Proterozoic Gillespie Lake Group dolomitic siltstones. The sulphide mineralization is localized within the axial planar cleavage of a kilometre-scale anticline and is dominated by galena- and sphalerite-cemented mosaic, rubble and crackle breccias with minor pyrite, galena, sphalerite and dolomite veins. 206Pb/204Pb values from galena range from 16.355 to 16.600, 207Pb/204Pb from 15.430 to 15.461, and 208Pb/204Pb from 36.016 to 36.283, respectively, and yield model ages between 1,490 and 1,430 Ma. A hydrothermal alteration zone, which is younger than the mineralization, has a poorly constrained U–Pb monazite age of 1,307 ± 180 Ma, which suggests that the Blende deposit is Proterozoic in age. Dolomites associated with the main- and late-stage mineralization have δ13C values that range from −1.8 to 0.9 ‰ and δ18O values of 15.7 to 21.9 ‰. The total range of δ34S values from pyrite, galena and sphalerite is 9.4 to 58.1 ‰, indicating that the sulphur in the deposit was derived from reduction of seawater sulphate in a closed system. Strontium isotopes suggest there were three fluids involved in the Blende mineralizing system: Fluid 1 was derived from seawater and formed carbonate and quartz veins pre-mineralization; it has an 87Sr/86Sr ratio of 0.70948. Fluid 2 has a high 87Sr/86Sr ratio of 0.73866, and fluid 3 has a Sr isotopic ratio of 0.71602. Fluids 1 and 3 have similar isotopic compositions but different total Sr ion signals (a function of concentration). This suggests that fluids 1 and 3 may have ultimately been derived from Proterozoic seawater but have undergone different amounts of water–rock interaction. The isotopic and geochemical data suggest the mineralization formed when a H2S-rich fluid derived from seawater (fluid 3) mixed with a metal-bearing fluid (fluid 2) in the high permeability zones of the axial planar cleavage. The Blende deposit is an unusual carbonate-hosted massive sulphide deposit which has features of both Irish-type and clastic-dominated Zn–Pb deposits. The deposit formed in response to a change in tectonism from a compressional regime to extension and rifting.

Fragmentation of Co-Fe-Ta-B Bulk Metallic Glass

The main limitation of bulk metallic glasses for their application as structural materials is the large brittleness under the external loading. We analyzed the failure characteristics of Co43Fe20Ta5.5B31.5(at.%) bulk metallic glass deformed in a compression at the room temperature and a low strain rate. Under loading the amorphous structure can store high elastic energy. During the failure this energy is released and the alloy breaks into small particles or powder exhibiting a fragmentation mode. The nanoscale fracture surface morphology respects the micromechanisms of failure of the amorphous structure. The fracture surface consists of a smooth mirror cleavage zone and a river pattern zone with the nanosized dimples arranged in lines respecting the periodic corrugation zones oriented perpendicular to the crack propagation direction.

Evaluation of the diffusivity and susceptibility to hydrogen embrittlement of API 5L X80 steel welded joints

This paper presents a study of susceptibility to hydrogen embrittlement of API 5L X80 steel welded joints by SMAW and GTAW processes.&nbsp;By varying the consumables used and the use of the same interpass temperature three different welded joints were obtained.&nbsp;Tests of hydrogen embrittlement susceptibility were performed according to ASTM G129-2006 with an aqueous solution (Solution A - TM0177 / 2005 NACE) sodium thiosulfate (Na&nbsp;2&nbsp;S&nbsp;2&nbsp;O&nbsp;3&nbsp;) replacing the bubbling of H&nbsp;2S. From the elongation values ​​was observed that the joint obtained in all welding conditions showed susceptibility to hydrogen embrittlement, which was determined by the elongation ratio.&nbsp;The joints that showed higher levels of hardness showed higher susceptibility to hydrogen embrittlement.&nbsp;The joints obtained with higher welding speeds for the same amount of heat input presented a reduction in the rate of hydrogen embrittlement.&nbsp;All joints tested in solution showed fracture surfaces with quasi cleavage zones.

A fluid inclusion and isotopic study of an intrusion-related gold deposit (IRGD) setting in the 380 Ma South Mountain Batholith, Nova Scotia, Canada: evidence for multiple fluid reservoirs

A set of sheeted quartz veins cutting 380 Ma monzogranite at Sandwich Point, Nova Scotia, Canada, provide an opportunity to address issues regarding fluid reservoirs and genesis of intrusion-related gold deposits. The quartz veins, locally with arsenopyrite (≤5%) and elevated Au–(Bi–Sb–Cu–Zn), occur within the reduced South Mountain Batholith, which also has other zones of anomalous gold enrichment. The host granite intruded (P = 3.5 kbars) Lower Paleozoic metaturbiditic rocks of the Meguma Supergroup, well known for orogenic vein gold mineralization. Relevant field observations include the following: (1) the granite contains pegmatite segregations and is cut by aplitic dykes and zones (≤1–2 m) of spaced fracture cleavage; (2) sheeted veins containing coarse, comb-textured quartz extend into a pegmatite zone; (3) arsenopyrite-bearing greisens dominated by F-rich muscovite occur adjacent the quartz veins; and (4) vein and greisen formation is consistent with Riedel shear geometry. Although these features suggest a magmatic origin for the vein-forming fluids, geochemical studies indicate a more complex origin. Vein quartz contains two types of aqueous fluid inclusion assemblages (FIA). Type 1 is a low-salinity (≤3 wt.% equivalent NaCl) with minor CO2 (≤2 mol%) and has T h = 280–340°C. In contrast, type 2 is a high-salinity (20–25 wt.% equivalent NaCl), Ca-rich fluid with T h = 160–200°C. Pressure-corrected fluid inclusion data reflect expulsion of a magmatic fluid near the granite solidus (650°C) that cooled and mixed with a lower temperature (400°C), wall rock equilibrated, Ca-rich fluid. Evidence for fluid unmixing, an important process in some intrusion-related gold deposit settings, is lacking. Stable isotopic (O, D, S) analyses for quartz, muscovite and arsenopyrite samples from vein and greisens indicate the following: (1) δ18Oqtz = +11.7‰ to 17.8‰ and δ18Omusc = +10.7‰ to +11.2‰; (2) δDmusc = −44‰ to−54‰; and (3) δ34Saspy = +7.8‰ to +10.3‰. These data are interpreted, in conjunction with fluid inclusion data, to reflect contamination of a magmatic-derived fluid ( $$ {\delta^{{{18}}}}{{\hbox{O}}_{{{{\rm{H}}_{{2}}}{\rm{O}}}}} $$ ≤ +10‰) by an external fluid ( $$ {\delta^{{{18}}}}{{\hbox{O}}_{{{{\rm{H}}_{{2}}}{\rm{O}}}}} $$ ≥ +15‰), the latter having equilibrated with the surrounding metasedimentary rocks. The δ34S data are inconsistent with a direct igneous source based on other studies for the host intrusion ( $$ {\delta^{{{18}}}}{{\hbox{O}}_{{{{\rm{H}}_{{2}}}{\rm{O}}}}} $$ = +5‰) and are, instead, consistent with an external reservoir for sulphur based on δ34SH2S data for the surrounding metasedimentary rocks. Divergent fluid reservoirs are also supported by analyses of Pb isotopes for pegmatitic K-feldspar and vein arsenopyrite. Collectively the data indicate that the vein- and greisen-forming fluids had a complex origin and reflect both magmatic and non-magmatic reservoirs. Thus, although the geological setting suggests a magmatic origin, the geochemical data indicate involvement of multiple reservoirs. These results suggest multiple reservoirs for this intrusion-related gold deposit setting and caution against interpreting the genesis of intrusion-related gold deposit mineralization in somewhat analogous settings based on a limited geochemical data set.

Na 2O, K 2O, SiO 2 and Al 2O 3 release from potassic and calcic–sodic feldspars into alkaline solutions

The potential release of elements from potassic and calcic–sodic feldspars into the concrete pore solution was evaluated by ICP-MS using 1 N NaOH and KOH solutions at 80 °C in accordance with the conditions set in the chemical test method. Materials were characterized by petrography, XRD and by XRF analysis. The influence of textural and microstructural characteristics on the leaching process was also analyzed by immersing polished plates of each mineral in 1 N NaOH at 80 °C for 7 days. Optical microscope and SEM observations indicate that microstructural characteristics, such as cleavage zones, twins, grain–grain contact and the finer and less abundant phases in perthites, play a key role in the leaching process under alkaline conditions. Na 2O, K 2O, SiO 2 and Al 2O 3 are supplied by hydrolysis, although the participation of other processes cannot be ruled out.

Myosin motor mediated contraction is enough to produce cytokinesis in the absence of polymerisation

Actin filament networks play an active role in cytokinesis of eukaryotic cells. These networks, linked mainly by myosin, are concentrated below the cell membrane forming a spherical supporting shell. During cytokinesis, this network is modified such that a contractile ring is formed along the diameter of the shell. We present a realistic three-dimensional simulation model to study the dynamics of this spherical shell of elastic actin filaments and myosin motors. The results show compelling evidence that this fibre-spring model, with the motors activated in a narrow region around the division plane, is sufficient to reproduce most of the essential mechanics of cytokinesis: A spontaneous formation of a contractile ring, a characteristic filament orientation structure, and realistic cleavage furrow dynamics. These results demonstrate that, though cytokinesis is a highly complex process with large variation in intricate details, the fundamental dynamics are largely generic. In particular, motor mediated contraction of an unstructured filament mesh is sufficient to undergo division without concentrated and directed polymerization in the cleavage zone.

421: Hysteroscopic Myomectomy

Effectiveness of a technique for hysteroscopic resection of uterine submucous myomas G2 type. Prospective study Setting: University Hospital. Intervention: modified surgical technique of hysteroscopic myomectomy. First incision of the endometrial mucosa is made with Collins electrode until cleavage zone, connecting bridges between myoma and surrounding muscle fibres are resected nearly complete protrusion of the myoma into the uterine cavity, finally myoma is resected with hysteroresectoscope. The procedure was performed in 41 (93,1%) of 44 women. Of these 38 (92,6%) had myomas between 2 and 4 cm in diameter, 7 (7,4%) had myomas exceeding 4 cm. Mean operating time was 27 minutes (range 10-45) Conclusions: the technique is safe and preserve anatomo-functional uterine integrity reducing the risk of thermal and/or vascular damages and uterine perforation.