Effect of ultrasonic and mechanical vibration treatments on evolution of Mn-rich phases and mechanical properties of Al−12Si−4Cu−1Ni−1Mg−2Mn piston alloys

Effects of ultrasonic vibration(UV)and mechanical vibration(MV)on the Mn-rich phase modification and mechanical properties of Al−12Si−4Cu−1Ni−1Mg−2Mn piston alloys were investigated.The results show that the UV and UV+MV treatments can significantly refine and fragmentize the microstructures.In addition,UV treatment can significantly passivate the primary Mn-rich Al15Mn3Si2 intermetallics.The formation mechanisms of refinement and passivation of the grains and non-dendrite particles were discussed.Compared with the gravity die-cast alloys,the UV and UV+MV treated alloys exhibit improved tensile and creep resistance at room and elevated temperatures.These results can be attributed to the refinement of theα(Al)grains and the secondary intermetallics,the increased proportion of refined heat-resistant precipitates,and the formation of nano-sized Si particles.The ultimate tensile strength of the UV treated alloys at 350℃ exceeds that of commercial piston alloys.This indicates the high application potential of the developed piston alloys in density diesel engines.

Role of copper in tarnishing process of silver alloys in sulphide media

Silver and silver alloys usually tarnish,which causes some changes in their aesthetic appearance and electrical properties,due to their exposure to sulphide environments(H2S),and this is a problem in the field of corrosion and conservation of cultural heritage metallic artefacts.In this study,the role of copper content in the tarnishing process of 0.925,0.800 and 0.720 silver alloys in a 0.07 vol.%ammonium sulphide solution for different immersion periods was analyzed by electrochemical impedance spectroscopy(EIS)and scanning electron microscopy(SEM).The polarisation curves showed that the copper content and sulphide increased the corrosion current density and delayed the passivation of silver alloys.The impedance spectra collected at the open circuit potential(OCP)showed a single capacitive,incomplete and depressed loop,indicating that the charge transfer resistance decreased as the copper content increased in the alloys.In contrast,the double-layer capacitance increased as the copper content increased.The SEM-EDS analysis confirmed that the copper-rich phase in the silver alloys was selectively dissolved due to the preference of S to react with Cu,resulting in a localised attack,thus delaying the formation of a passive film.A marked localised attack was observed in alloys with lower copper content.The mechanism for the tarnishing of silver alloys in sulphide media was dependent on the nature of the alloy and the greater affinity of copper for sulphur.The dissolution of Ag and Cu to form corrosion products was proposed as the rate determining step.

Thyroid Cancer

Thyroid tumors include those that originate from follicular cells and those that arise from parafollicular cells (C cells). Differentiated thyroid cancer, which originates from follicular cells, includes papillary carcinoma, follicular carcinoma, oncocytic cell carcinoma (Hürthle), poorly differentiated carcinoma, and anaplastic carcinoma. The incidence of thyroid cancer has been increasing significantly, with an estimated incidence in the United States of America of 53,990 cases by the year 2018. This neoplasm is listed as the most common endocrine tumor and represents approximately 3% of all malignant tumors in humans, with 75% of cases occurring in women, and two-thirds of cases occurring in people under 55 years. The increase in the prevalence/incidence of low-risk thyroid cancer over the last 10 to 20 years has required a re-appraisal of the standard one-size-fits-all approach to differentiated thyroid cancer. This adaptation to a more individualized management of the patient with thyroid cancer has led to a much more risk-adapted approach to the diagnosis, initial therapy, adjuvant therapy, and follow-up of patients with differentiated thyroid cancer. This paper with review the current understanding of the clinical presentation, diagnostic workup, and management of thyroid cancer centered on evidence-based and personalized medicine.

Recycling of Glass Fibers from Fiberglass Polyester Waste Composite for the Manufacture of Glass-Ceramic Materials

This work presents the feasibility of reusing a glass fiber resulting from the thermolysis and gasification of waste composites to obtain glass-ceramic tiles. Polyester fiberglass (PFG) waste was treated at 550℃ for 3 h in a 9.6 dm3 thermolytic reactor. This process yielded an oil (≈24 wt%), a gas (≈8 wt%) and a solid residue (≈68 wt%). After the polymer has been removed, the solid residue is heated in air to oxidize residual char and remove surface contamination. The cleaning fibers were converted into glass-ceramic tile. A mixture consisting of 95 wt% of this solid residue and 5% Na2O was melted at 1450℃ to obtain a glass frit. Powder glass samples (<63 μm) was then sintered and crystallized at 1013℃, leading to the formation of wollastonite-plagioclase glass-ceramic materials for architectural applications. Thermal stability and crystallization mechanism have been studied by Differential Thermal Analysis. Mineralogy analyses of the glass-ceramic materials were carried out using X-ray Diffraction.

Production of Ag-ZnO powders by hot mechanochemical processing

Ag–CdO composites are still one of the most commonly used electrical contact materials in low-voltage applications owing to their excellent electrical and mechanical properties.Nevertheless,considering the restriction on using Cd due to its toxicity,it is necessary to find alternative materials that can replace these composites.In this study,the synthesis of Ag-ZnO alloys from Ag-Zn solid solutions was investigated by hot mechanochemical processing.The hot mechanochemical processing was conducted in a modified attritor mill at 138℃under flowing O2 at 1200 cm3/min for 3.0 h.The microstructure and phase evolution were investigated using X-ray diffractometry,field emission gun scanning electron microscopy and transmission electron microscopy.The results suggest that it is possible to complete the oxidation of Ag-Zn solid solution by hot mechanochemical processing at a low temperature and short time.This novel synthesis route can produce Ag-ZnO composites with a homogeneous distribution of nanoscale ZnO precipitates,which is impossible to achieve using the conventional material processing methods.Considering the fact that the fundamental approach to improving electric contact material performance resides in obtaining uniform dispersion of the second-phase in the Ag matrix,this new processing route could open the possibility for Ag-ZnO composites to replace non-environmentally friendly Ag-CdO.

Up to Date Management of DCIS and Future Directions

Ductal carcinoma in situ (DCIS) is a non-invasive malignancy confined within the basement membrane of the breast ductal system. There is a lot of disparity in the natural history of DCIS with an estimated incidence of progression to invasive ductal carcinoma between 20% to 53% over ten or more years after initial diagnosis. The surgical and adjuvant management of DCIS has advanced significantly in the last couple of decades. Nonetheless, surgeons, medical oncologists, and radiation oncologists, along with their patients, still depend on conventional clinical and pathologic risk factors to make management decisions. Irrespective of the management strategy, long-term survival is excellent. The debate around DCIS relates to preventing either under-treatment or over-treatment. In this paper, we will review the incidence and management options of DCIS. Additionally, we will focus on several current disputes related to the management of DCIS, including breast conserving surgery, the role of radiation in breast conservation surgery, sentinel node biopsy in DCIS, hormonal therapy, various risk stratification schemes, and the option of active surveillance for low-risk DCIS.

A facile one-pot hydrothermal synthesis as an efficient method to modulate the potassium content of cryptomelane and its effects on the redox and catalytic properties

Cryptomelane has been widely applied as catalyst in oxidation reactions due to its excellent redox properties and low cost.Here,a novel one-pot hydrothermal synthesis using a potassium permanganate aqueous solution as precursor and ethanol as reducing agent has successfully been developed to obtain cryptomelane nano-oxides.This synthetic route makes it possible to control the amount of potassium incorporated into the structure of the cryptomelane by selecting the appropriate synthesis temperature and ethanol initial concentration.Taking advantage of this approach,the effect of potassium concentration on the structural stability and reducibility of the cryptomelane,which are poorly discussed in the literature,has been studied.We have observed that samples with low content of potassium(~11%)show high conversions of CO to CO2 especially at low temperatures.The lower activity of the samples with high K contents(~16%)can be ascribed to the beneficial effect of K on the structural stability of cryptomelane in detriment of labile oxygen on cryptomelane surface.

Effect of Sn on synthesis of nanocrystalline Ti-based alloy with fcc structure

The effect of the amount of Sn on the formation of fcc phase in Ti-13 Ta-x Sn(x=3,6,9 and 12,at.%)alloys was studied.The alloys were synthesized by mechanical alloying using a planetary mill,jar and balls of stabilized yttrium.Using Rietveld refinement,it was found that the obtained fcc phase has crystallite size smaller than 10 nm and microstrain larger than 10-3.Both conditions are required to form an fcc phase in Ti-based alloys.For all samples,the microstructure of the fcc phase consists of equiaxial crystallites with sizes smaller than 10 nm.The largest presence of fcc phase in the studied Ti alloy was found with 6 at.%Sn,because this alloy exhibits the largest microstrain(1.5×10-2)and crystallite size of 6.5 nm.Experimental data reveal that a solid solution and an amorphous phase were formed during milling.The necessary conditions to promote the formation of solid solution and amorphous phases were determined using thermodynamic calculations.When the amount of Sn increases,the energy required to form an amorphous phase varies from approximately 10 to approximately-5 k J/mol for 3 and 12 at.%Sn,respectively.The thermodynamic calculations are in agreement with XRD patterns analysis and HRTEM results.

Phylogeny of Bacteria from Steelmaking Wastes and Their Acidic Enrichment Cultures

Currently, millions of tons of steel are produced worldwide. This has become a serious economic and environmental challenge because the ores used for steel production are nonrenewable resources and the production generates huge amount of waste. In this study, we identified and investigated the ability of bacteria from steelmaking waste with low and high zinc concentration to promote leaching of zinc, when enriched by acidic (pH 2) culture conditions. The bioleaching assays indicated removal of Zn, as in chemical leaching. Bacterial communities from crude and enrichment culture wastes were characterized by the 16S rRNA gene. Phylogenetic analysis of the generated clone libraries revealed predominance of Proteobacteria and Firmicutes. The Actino- bacteria, Bacteroidetes, Cyanobacteria, and Deinococcus-Thermus phyla were also encountered. The clones were most closely related to cultivable heterotrophic bacteria. Different genera were identified including iron redox cycling and leaching bacteria such as Chromobacterium, Aeromonas, Escherichia, Bacillus, and Ochrobactrum. These data add significant new information on bacteria which survive in extremely acidic conditions. They are distantly related to typical acidophiles responsible for the leaching process, which makes them good candidates for future studies on metal bioleaching.

Helicobacter pylori vacA s1a and s1b alleles from clinical isolates from different regions of Chile show a distinct geographic distribution

AIM： To establish the most common vacA alleles in Helicobacter pylori （ H pylon） strains isolated from Chilean patients and its relationship with gastritis and gastroduodenal ulcers, METHODS： Two hundred and forty five Hpyloriclinical isolates were obtained from 79 biopsies from Chilean infected patients suffedng from gastrointestinal diseases. An average of 2-3 strains per patient was isolated and the vac4 genotype was analyzed by PCR and 3% agarose electrophoresis. Some genotypes were checked by DNA sequencing. RESULTS： The most prevalent vacA genotype in Chilean patients was slb ml （76%）, followed by sla ml （21%）. In oontrast, the s2 m2 genotype was scarcely represented （3%）. The slb ml genotype was found most frequently linked to gastropathies （P〈0.05） rather than ulcers. Ulcers were found more commonly in male and older patients. Curiously, patents IMng in dties located North and far South of Santiago, thecapital and largest Chilean city, carried almost exclusively strains with the slb ml genotype. In contrast, patients from Santiago and cities located South of Santiago carded strains with either one or both sla ml and slb ml genotypes. Regarding the s2 m2 genotype, comparison with GenBank sequences revealed that Chilean s2 sequence was identical to those of Australian, American, and Colombian strains but quite different from those of Alaska and India. CONCLUSION： Differences in geographic distribution of the s and m vacA alleles in Chile and a relationship of slb ml genotype with gastritis were found. Sequence data in part support a hispanic origin for the vacA genotype. Asymmetric distribution of genotypes slb ml and s2 m2 recedes H Pyloristrain distribution in Spain and Portugal.

Effect of V-Ti on the Microstructure and Abrasive Wear Behavior of 6CrC Cast Steel Mill Balls

Iron-chromium cast alloys are basically abrasive wear resistant materials particularly employed in mining industry;these alloys are often utilized in the manufacture of milling balls. In particular, high Cr and high C cast alloys have been subjected of significant research;for instance, most reports have been addressed on analyzing the relation between microstructure and the abrasive wear behavior;however, there exist a reduced number of reports on relatively low Cr and low C cast alloys. In this research, five low Cr cast steels containing additions of V and Ti were melted in an open atmosphere induction furnace. Comparisons on the morphology, size, type and distribution of carbides were carried through optical microscopy, SEM and XRD. Hardness testing was employed at room temperature with the purpose of correlate to wear behavior. A laboratory pilotplant ball-mill set with a batch of ore was utilized in order to evaluate the abrasive wear resistance. According to microstructure observations, a martensitic primary matrix was revealed in all specimens. The fraction of M7C3 and M3C interdendritic eutectic carbides varied according to alloying level. Further results indicated that variations in the shape and size of M7C3 and M3C along with the presence of V and Ti carbides influenced on the abrasive wear behavior of low Cr cast steel mill balls.

Dissolution Behavior of Gold in Alkaline Media Using Thiourea

In this work the dissolutive behavior of gold in alkaline medium using thiourea (TU), under different variables, was studied in a theoretical and experimental way, in order to determine the conditions under which it is feasible to dissolve gold in thiourea-alkaline medium. A thermodynamic study was conducted by chemical speciation using the method of Ro-jas-Hernández, together with an electrochemical study where the electric potential was swept in the anodic direction. The main results of the thermodynamic study were that formamidine disulfide (FDS) and sulfinic compounds (S.C.) prevail at alkaline pH;by increasing the initial concen-tration of thiourea at alkaline pH, the presence of the gold complex is al-most zero for any initial concentration of thiourea. By including sodium sulfite in the gold-thiourea system, it was possible to obtain the Au(I)-TU complex at alkaline pH, with a presence of 95.13%. Electrochemical tests allowed verifying that in the absence of sodium sulfite the dissolution of gold in an alkaline medium is very slow but adding sodium sulfite im-provements become evident in the dissolution of the metal. Therefore, sodium sulfite catalyzes the gold dissolution process and stabilizes the thiourea. With this study it was possible to establish the feasibility of using thiourea in an alkaline medium for the dissolution of gold, and the conditions under which it is possible to dissolve the gold in that medium. With these fundamentals and conditions, it is now possible to move forward to test this system for minerals and/or concentrates containing gold.

Synthesis of palladium-rhodium bimetallic nanoparticles for formic acid dehydrogenation

Herein,we report for the first time the synthesis of preformed bimetallic Pd-Rh nanoparticles with different Pd:Rh ratios(nominal molar ratio:80-20,60-40,40-60,20-80) and the corresponding Pd and Rh monometallic ones by sol immobilization using polyvinyl alcohol(PVA) as protecting agent and NaBH4 as reducing agent,using carbon nanofibers with high graphitization degree(HHT) as the desired support.The synthesized catalysts were characterized by means of Transmission Electron Microscopy(TEM) and inductively coupled plasma optical emission spectroscopy(ICP-OES).TEM shows that the average particle size of the Pd-Rh nanoparticles is the range of 3-4 nm,with the presence of few large agglomerated nanoparticles.For bimetallic catalysts,EDX-STEM analysis of individual nanoparticles demonstrated the presence of random-alloyed nanoparticles even in all cases Rh content is lower than the nominal one(calculated Pd:Rh molar ratio:90-10,69-31,49-51,40-60).The catalytic performance of the Pd-Rh catalysts was evaluated in the liquid phase dehydrogenation of formic acid to H2.It was found that Pd-Rh molar ratio strongly influences the catalytic performance.Pd-rich catalysts were more active than Rh-rich ones,with the highest activity observed for Pd90:Rh10(1792 h^(-1)),whereas Pd69:Rh31(921 h^(-1)) resulted the most stable during recycling tests.Finally,Pd90:Rh10 was chosen as a representative sample for the liquid-phase hydrogenation of muconic acid using formic acid as hydrogen donor,showing good yield to adipic acid.

Management Approach to Thyroid Nodules

Thyroid nodules are a major health problem worldwide. The prevalence of palpable thyroid nodules in the general population is approximately 5% in women and 1% in men living in parts of the world with sufficient iodine. High resolution neck and thyroid ultrasound can detect thyroid nodules in a significant proportion of randomly selected individuals, with higher frequencies in women and the elderly population. The importance of thyroid nodules lies in the need to rule out cancer. The majority of thyroid nodules are benign, clinically irrelevant, and can be safely managed with a good surveillance program. The detection and diagnosis of differentiated thyroid cancer have evolved over the years with increased use of high resolution cervical and thyroid ultrasound, fine needle aspiration biopsy (FNAB), molecular testing, and thyroglobulin as a serum tumor marker. An algorithm that utilizes high resolution ultrasound and, when indicated, FNAB, and molecular testing for the diagnosis of thyroid nodules, facilitates a personalized, risk-based protocol that promotes high-quality care and minimizes cost and unnecessary testing. Our paper reviews the current, evidence-based management of newly diagnosed thyroid nodules.

Robotic transanal total mesorectal excision:Is the future now?

Total mesorectal excision(TME)is the standard surgical treatment for the curative radical resection of rectal cancers.Minimally invasive TME has been gaining ground favored by the continuous technological advancements.New procedures,such as transanal TME(TaTME),have been introduced to overcome some technical limitations,especially in low rectal tumors,obese patients,and/or narrow pelvis.The earliest TaTME reports showed promising results when compared with the conventional laparoscopic TME.However,recent publications raised concerns regarding the high rates of anastomotic leaks or local recurrences observed in national series.Robotic TaTME(R-TaTME)has been proposed as a novel technique incorporating the potential benefits of a perineal dissection together with precise control of the distal margins,and also offers all those advantages provided by the robotic technology in terms of improved precision and dexterity.Encouraging short-term results have been reported for R-TaTME,but further studies are needed to assess the real role of the new technique in the long-term oncological or functional outcomes.The present review aims to provide a general overview of R-TaTME by analyzing the body of the available literature,with a special focus on the potential benefits,harms,and future perspectives for this novel approach.

The role of physical properties in explosive welding of copper to stainless steel

This paper investigates the effects of the physical properties on the microstructure and weldability of explosive welding by joining two metals with a significant contrast in thermophysical properties:stainless steel and copper.Sound welds between stainless steel and copper were obtained,and the interfacial morphology was wavy,regardless of the position of the materials.The weldability of dissimilar pairs was found to be more dependent on the relationship between the physical properties of the base materials than on the absolute value of the material property.When there is a significant difference in thermal conductivity between the flyer and the base plate,together with a material with a low melting temperature,the weldability of the pair is often poor.The relative position of the plates affects the interfacial microstructure even when similar morphologies are found.For the metallic pairs studied,the wave size was bigger for the configuration in which the ratio between the density of the flyer and the density of the base plate is smaller.The same phenomenon was observed for the impedance:bigger waves were found for a smaller ratio between the impedance of the flyer and the impedance of the base plate.

CST 2号连铸机轴的失效分析

自2号连铸机投产以来,连铸机垂直部分辊的中间轴承出现断裂.CST的工程部用数值法(FEA)分析了这个问题,为了确认浇注过程中铸机任意部分的轴承载荷,分析初始设计的两分离辊结构,发现导致辊子损坏的临界载荷.鉴于数值法发现高载荷的存在,CST决定安装一个辊轴载荷检测系统来追踪所有工况.在这个研究中,针对两辊结构,结合数值法和实验法进行分析.将分析结果应用在一个新的三辊结构中.最终制定了一个减少辊子失效的实施计划.

Kinetic behaviour of commercial catalysts for methane reforming in ethanol steam reforming process

Ethanol steam reforming has been studied in a fluidized bed （in order to ensure bed isothermicity） on commercial catalysts for methane reforming. The results allow analyzing the effect of temperature （in 300-700℃ range）, and both metal and support nature on the reaction indices （ethanol conversion, yields and selectivities to H2 and byproducts （CO2, CO, CH4 and C2H4O））. Special attention has been paid to catalysts＇ stability by comparing the evolution of the reaction indices with time on stream at 500°C （minimum CO formation） and 700℃ （minimum deactivation by coke deposition）. Although they provide a slightly lower H2 yield, the results evidence a good behaviour of Ni based catalysts, indicating that they are an interesting alternative of more expensive Rh based ones.

Radon exhalation from phosphogypsum stabilized in sulfur polymer cement

Phosphogypsum (PG), primary by-product from phosphoric acid production, is accumulated in large stock-piles which were active until 2010, when spills were banned. It is considered as NORM material that contains radionuclides from 238U and decay series which are of most radiotoxicity. PG was valorized and/or recycled in a building material, sulfur polymer cement (SPC). The SPC-PG samples reach the international regulation to use in the manufacture of building materials without radiological restrictions, except the sample with the 50% of PG. Under normal conditions of ventilation the contribution to the expected radon indoor concentration is also below the international recommendation.

Physico-Chemical Characteristics of the Products Derived from the Thermolysis of Waste <i>Abies</i><i>alba</i><i>Mill</i>. Wood

This paper reports the physico-chemical characteristics of the products derived from the thermolysis (thermolytic distillation) of waste silver fir (Abies alba Mill.) wood at different temperatures (400℃- 600℃) in a pilot scale plant. Depending on the thermolysis temperature, the procedure yielded 45 - 53 wt% pyroligneous acid with a high water content (80 - 86 wt%) and pH ≈ 3.6. The process also produced a carbonaceous solid or biochar (23 - 26 wt%), its properties strongly dependent on the thermolysis temperature. Gases (20 - 31 wt%) were also produced;these were transformed into electrical energy via a gas turbine. The pyroligneous acid was centrifuged to isolate a subfraction composed mostly of phenols (phenol, mequinol and furfural) with a total C content of 68 - 74 wt%. The remainder was subjected to fractionated distillation at laboratory scale, and the distillate subjected to liquid-liquid extraction using diethyl ether in two stages to obtain a bio-oil composed mainly of acetic acid (≈47%), aldehydes, ketones and alcohols (≈31%), phe- nols (≈18%) and aliphatic alcohols. The characteristics of the bio-oil depended on the thermolysis temperature.