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Recovery of Gold and Silver and Removal of Copper, Zinc and Lead Ions in Pregnant and Barren Cyanide Solutions

Materials Sciences and Applications 2015年第2期6卷 171-182页

作者： Gabriela Figueroa Jesus L. valenzuela jose R. Parga Victor Vazquez Alejandro valenzuela Department of Chemical Engineering and Metallurgy University of Sonora Hermosillo Mexico Department of Materials Science Technological Institute of Saltillo Saltillo Mexico

Over the past decade the concern about toxic metals in freshwater has increased. Environmental laws such as the Clean Water Act have forced industries that produce metal containing wastewater to treat their wastewater prior to discharge. The purpose of this study was to investigate the use of a novel method for the minimization of heavy metals in the wastewater from the mining industry. A very promising electrochemical treatment technique that does not require chemical additions is electrocoagulation (EC) and sulphide precipitation. The present study has been done for the recovery of gold and silver contained in pregnant solution from the cyanidation process using the electrocoagulation technology with iron electrodes;that is a developed alternative technology for the Merril-Crowe process. The average gold and silver content in pregnant solution was 4.27 and 283 ppm respectively and the recoveries were 92% for gold and 95% for silver, with optimum operating parameters of pH 10, residence time of 20 minutes and addition of sodium chloride of 4 gr/L. The results of precipitation process show that the elimination of lead, zinc, cooper and iron ions from the barren solution was successful, with optimum operating parameters of pH 3 and residence time of 15 minutes, and the recoveries were 99% of these ions. Finally the characterization of the solid products of gold and silver formed during the EC process with Scanning Electronic Microscope was performed. Results suggest that magnetite particles and amorphous iron oxyhydroxides (lepidocrocite) were present.

关键词： Electrochemical Process Precipitation Process Gold and Silver Cyanides

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Synthesis and Characterization of Green Potassium Nanoparticles from Sideroxylon Capiri and Evaluation of Their Potential Antimicrobial

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Journal of Renewable Materials 2021年第10期9卷 1699-1706页

作者： Judith Constantino-Alcazar Miguel Abud-Archila Benjamín Valdez-Salas Federico Gutierrez-Miceli Carlos Ceceña-Duran Blanca López-valenzuela Daniel Gonzalez-Mendoza Tecnológico Nacional de México Instituto Tecnológico de Tuxtla GutiérrezTuxtlaGutiérrezC.P.03940México Instituto de Ciencias Agrícolas de la Universidad Autónoma de Baja California(ICA-UABC) Ejido Nuevo LeónC.P.21705México Instituto de Ingeniería de la Universidad Autónoma de Baja California Mexicali21100México

In the present study,the green synthesis of potassium nanoparticles(K-NPs)was assessed using aqueous extract of Sideroxylon *** potassium nanoparticles were analyzed by UV-visible spectroscopic techniques,X-ray spectrometers of energy dispersive(SEM-EDS)and dynamic light *** results showed high values at 3.5 keV confirming the formation of potassium nanoparticles and the SEM analysis showed an agglomerated particles size between 360 to 200 nm with a spherical *** K-NPs showed an effective antibacterial activity against the test organisms mainly with Bacillus cereus,Enterobacter aerogenes,Fusarium solani and Botrytis *** further studies about nanotoxicity of K-NPs are needed to confirm their potential in the control of the pathogen microorganisms under field conditions.

关键词： Antimicrobial effect green synthesis Sideroxylon capiri biocontrol

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Practical Universal Method for Designing Single-Layer Electromagnetic Wave Absorbers

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Open Journal of Antennas and Propagation 2018年第4期6卷 84-92页

作者： Benjamin Jacard Alvaro valenzuela Manuel Gonzalez Department of Electrical Engineering University of Chile Santiago Chile

A simple design method for electromagnetic wave absorbers under normal incidence is presented. For the fabrication of the microwave absorbing material a novel design chart is used, including curves of constant ?ratio in a? plane. The practical use of the chart is explained and, as example, a microwave absorber fabricated with magnetite-impregnated plastisol is designed and tested at X-band frequencies.

关键词： Permittivity Permeability Single Layer Microwave Absorption Reflection Loss

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Surgical treatment of acute cholecystitis in patients with confirmed COVID-19:Ten case reports and review of literature

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World Journal of Clinical Cases 2022年第4期10卷 1296-1310页

作者： Katya Bozada-Gutierrez Mario Trejo-Avila Fatima Chavez-Hernandez Sara Parraguirre-Martinez Carlos valenzuela-Salazar Jesus Herrera-Esquivel Mucio Moreno-Portillo Department of General and Endoscopic Surgery Hospital General Dr.Manuel Gea GonzalezMexico City 14090Mexico Department of Pathology Hospital General Dr.Manuel Gea GonzalezMexico City 14090Mexico

BACKGROUND Research concerning postoperative outcomes of confirmed coronavirus disease 2019(COVID-19)patients revealed unfavorable postoperative results with increased morbidity,pulmonary complications and *** reports have suggested that COVID-19 is associated with more aggressive presentation of acute *** aim of the present study is to describe the perioperative assessment and postoperative outcomes of ten patients with confirmed severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection with concomitant acute cholecystitis who underwent *** SUMMARY We report a total of 10 SARS-CoV-2 positive patients with concomitant acute cholecystitis that underwent *** patients were males,the mean age was 47.1 *** patients had moderate acute cholecystitis,and one patient had severe acute *** patients were treated with urgent/early laparoscopic *** the Parkland grading scale,two patients received a Parkland grade of 3,two patients received a Parkland grade of 4,and six patients received a Parkland grade of *** patients required a bail-out *** patients developed biliary leakage and required endoscopic retrograde cholangiopancreatography with biliary *** surgery,five patients developed acute respiratory distress syndrome(ARDS)and required intensive care unit(ICU)*** patient died after cholecystectomy due to ARDS *** mean total length of stay(LOS)was 18.2 *** histopathology demonstrated transmural necrosis(n=5),vessel obliteration with ischemia(n=3),perforation(n=3),and acute peritonitis(n=10).CONCLUSION COVID-19 patients with acute cholecystitis had difficult cholecystectomies,high rates of ICU admission,and a prolonged LOS.

关键词： COVID-19 SARS-CoV-2 Cholecystectomy in COVID-19 Acute cholecystitis in COVID-19 Case report

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Neurocognitive outcomes in pediatric brain tumors after treatment with proton versus photon radiation:a systematic review and meta-analysis

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世界儿科杂志:英文版 2023年第8期19卷 727-740页

作者： Álvaro Lassaletta Javier S.Morales Pedro L.valenzuela Borja Esteso Lisa S.Kahalley Donald J.Mabbott Soumya Unnikrishnan Elena Panizo Felipe Calvo Radiation Oncology Department Clínica Universidad de NavarraCalle Marquesado de Santa Marta 128027 MadridSpain Pediatric Neuro-Oncology Unit Hospital Infantil Universitario Niño JesúsMadridSpain MOVE-IT Research Group Department of Physical EducationFaculty of Education SciencesUniversity of CadizCádizSpain Biomedical Research and Innovation Institute of Cádiz(INiBICA)Research Unit Puerta del Mar University HospitalUniversity of CádizCádizSpain Physical Activity and Health Research Group(PaHerg) Research Institute of the Hospital 12 de Octubre(‘imas12’)MadridSpain Systems Biology Department University of AlcaláMadridSpain Clinical Neuropsychology Unit Psychiatry and Clinical Psychology DepartmentHospital Infantil Universitario Niño JesúsMadridSpain Baylor College of Medicine HoustonTXUSA Texas Children’s Hospital HoustonTXUSA The Hospital for Sick Children TorontoONCanada The University of Toronto TorontoONCanada University of California School of Medicine San DiegoLa JollaCAUSA

Background Advances in cancer treatments,particularly the development of radiation therapy,have led to improvements in survival outcomes in children with brain ***,radiation therapy is associated with significant long-term neurocognitive *** present systematic review and meta-analysis aimed to compare the neurocognitive outcomes of children and adolescents with brain tumors treated with photon radiation(XRT)or proton therapy(PBRT).Methods A systematic search was conducted(PubMed,Embase,Cochrane,and Web of Science from inception until 02/01/2022)for studies comparing the neurocognitive outcomes of children and adolescents with brain tumors treated with XRT *** pooled mean differences(expressed as Z scores)were calculated using a random effects method for those endpoints analyzed by a minimum of three *** Totally 10 studies(n=630 patients,average age range:1–20 years)met the inclusion *** who had received PBRT achieved significantly higher scores(difference in Z scores ranging from 0.29–0.75,all P0.05 in main analyses or sensitivity analyses)were found for nonverbal memory,verbal working memory and working memory index,processing speed index,or focused *** Pediatric brain tumor patients who receive PBRT achieve significantly higher scores on most neurocognitive outcomes than those who receive *** studies with long-term follow-ups are needed to confirm these results.

关键词： Brain health Childhood cancer Intelligence quotient Radiotherapy

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Kinetic Aspects of Gold and Silver Recovery in Cementation with Zinc Power and Electrocoagulation Iron Process

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Advances in Chemical Engineering and Science 2012年第3期2卷 342-349页

作者： Gabriela V. Figueroa Martinez josé R. Parga Torres Jesús L. valenzuela García Guillermo C. Tiburcio Munive Gregorio González Zamarripa Department of Chemical Engineering and Metallurgy University of Sonora Hermosillo México Department of Metallurgy and Materials Science Institute of Technology of Saltillo Saltillo México

The Merrill-Crowe or Cementation process is used for concentration and purification of gold and silver from cyanide solutions. Among other available options for recovery of precious metals from cyanide solutions, Electrocoagulation (EC) is a very promising electrochemical technique for the recovery of this precious metals. In this work first, an introduction to the fundamentals of the Merrill Crowe and EC process are given, then Kinetic aspects conditions and results of the both process, for the removal of gold and silver from cyanide solutions are presented, and finally the characterization of the solid products formed during the EC process with X-ray Diffraction and SEM are shown. Results suggests that The cementation of both gold and silver by suspended zinc particles conforms to well-behaved fist order kinetics and for the EC process the results show that is an excellent option to remove Au and Ag from cyanide solution by using iron electrodes. Finally, 99.5% of gold and silver were removed in the experimental EC reactor, and it was achieved in 5 minutes or less.

关键词： Cyanidation Merrill Crowe Electrocoagulation Kinetics

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Hetero-trans-β-Glucanase Produces Cellulose-Xyloglucan Covalent Bonds in the Cell Walls of Structural Plant Tissues and Is Stimulated by Expansin

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Molecular Plant 2020年第7期13卷 1047-1062页

作者： Klaus Herburger Lenka Frankova Martina Picmanova Jia Wooi Loh Marcos valenzuela-Ortega Frank Meulewaeter Andrew D.Hudson Christopher E.French Stephen C.Fry The Edinburgh Cell Wall Group Institute of Molecular Plant SciencesSchool of Biological SciencesThe University of EdinburghEdinburgh EH93BFUnited Kingdom Institute of Quantitative Biology Biochemistry and BiotechnologySchool of Biological SciencesThe University of EdinburghEdinburgh EH93BFUnited Kingdom BASF BBCC Innovation Center Gent-Trait Research9052 Gent(Zwijnaarde)Belgium Zhejiang University-University of Edinburgh Joint Research Centre for Engineering Biology Zhejiang UniversityHainingZhejiang 314400China Present address:Section for Plant Glycobiology Department of Plant and Environmental SciencesUniversity of CopenhagenFrederiksberg 1871Denmark

Current cell-wall models assume no covalent bonding between cellulose and hemicelluloses such as xyloglu-can or mixed-linkageβ-D-glucan(MLG).However,Equisetum hetero-trans-β-glucanase(HTG)grafts cellu-lose onto xyloglucan oligosaccharides(XGOs)-and,we now show,xyloglucan polysaccharide-in vitro,thus exhibiting CXE(cellulose:xyloglucan endotransglucosylase)*** addition,HTG also catalyzes MLG-to-XGO bonding(MXE activity).In this study,we explored the CXE action of HTG in native plant cell walls and tested whether expansin exposes cellulose to HTG by disrupting hydrogen *** quantify and visu-alize CXE and MXE action,we assayed the sequential release of HTG products from cell walls pre-labeled with substrate *** demonstrated covalent cellulose--xyloglucan bonding in plant cell walls and showed that CXE and MXE action was up to 15%and 60%of total transglucanase action,respectively,and peaked in aging,strengthening tissues:CXE in xylem and cells bordering intercellular canals and MXE in *** bacterial expansin(EXLX1)strongly augmented CXE activity in *** and MXE ac-tion in living Equisetum structural tissues potentially strengthens stems,while expansin might augment the HTG-catalyzed CXE reaction,thereby allowing efficient CXE action in *** methods will enable surveys for comparable reactions throughout the plant ***,engineering similar hetero-polymer formation into angiosperm crop plants may improve certain agronomic traits such as lodging tolerance.

关键词： cell wall cellulose hemicelluloses hetero-trans-p-glucanase hetero-transglycosylation xyloglucan

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Trichoderma *** Bacillus *** growth promoters in maize(Zea mays L.)

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Phyton-International Journal of Experimental Botany 2019年第1期88卷 37-46页

作者： López-valenzuela BE Armenta-Bojórquez AD Hernández-Verdugo S Apodaca-Sánchez MA Samaniego-Gaxiola JA Valdez-Ortiz A Universidad Autónoma de Sinaloa.Facultad de Agricultura del Valle del Fuerte.Avenida Japaraqui y Calle 16 s/n Juan JoséRíosSinaloaC.P 81110México Universidad Autónoma de Baja California.Instituto de Ciencias Agrícolas.Carretera a Delta s/n Ejido Nuevo leónBaja CaliforniaC.P.21705México Instituto Politécnico Nacional.Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional Unidad Sinaloa.Blvd.Juan de Dios Bátiz Paredes#250 Colonia San JoachinGuasaveSinaloaC.P.81101México Universidad Autónoma de Sinaloa Facultad de Agronomía.Km.17.5Carretera Culiacán-El DoradoCuliacán RosalesSinaloaC.P.80000México Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias Campo Experimental La LagunaBlvd.JoséSantos Valdez 1200 Pte.MatamorosCoahuilaC.P.27440México Universidad Autónoma de Sinaloa Facultad de Ciencias Químico Biológicas.Calzada de las Américas y Calle Universitarioss/n.Ciudad UniversitariaCuliacánSinaloaC.P.80013México

Microbes that are beneficial to plants are used to enhance the crop growth,yield and are alternatives to chemical *** and Bacillus are the predominant plant growth-promoting fungi and *** objective of this study was select,characterize,and evaluate isolates of Trichoderma *** Bacillus *** from the northern region of Sinaloa,Mexico,and assess their effect on growth promotion in maize(Zea mays L.).In greenhouse conditions,four Trichoderma isolates and twenty Bacillus isolates,as well as two controls,were tested in a completely randomized design with three *** selected the two best strains of Trichoderma and Bacillus:TB=Trichoderma asperellum,TF=Trichoderma virens,B14=Bacillus cereus sensu lato and B17=Bacillus cereus,which were evaluated in the field in a completely randomized blocks in factorial arrangement design with three replicates applying different rates of nitrogen fertilizer(0,150 kg N/ha,and 300 kg N/ha).Treatments 5(B17=***)and 11(TF=***)both fertilized with 150 kg N/ha showed similar yields and they did not reveal significant differences from the treatments fertilized with 300 kg N/*** indicated that treatment 5(B17=*** with 150 kg N/ha)and treatment 11(TF=*** with 150 kg N/ha)were efficient as growth promoters,by not showing significant differences in root volume and dry weight of *** results indicated a reduction of 50% in the rate of nitrogen to fertilizer required for maize(Zea mays L.)*** microorganisms Trichoderma and Bacillus could be an alternative to reduce the use of chemical fertilizers in maize.

关键词： Trichoderma Bacillus Native strains Biofertilizers

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Optimal length of triple therapy for H pylori eradication in a population with high prevalence of infection in Chile

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World Journal of Gastroenterology 2007年第21期13卷 2967-2972页

作者： Arnoldo Riquelme Alejandro Soza Cesar Pedreros Andrea Bustamante Felipe valenzuela Francisco Otarola Eduardo Abbott Marco Arellano Brenda Medina Alejandro Pattillo Douglas Greig Marco Arrese Antonio Rollan Department of Gastroenterology Pontificia Universidad Católica de Chile Hospital de Urgencia Asistencia Pública SantiagoChile Department of Internal Medicine Pontificia Universidad Católica de Chile

AIM:To compare the efficacy of 7-d versus 14-d triple therapy for the treatment of H pylori infection in Chile,with a prevalence of 73% in general population. METHODS:H pylori-infected patients diagnosed by rapid urease test,with non-ulcer dyspepsia or peptic ulcer disease were randomized to receive omeprazole 20 mg bid,amoxicillin 1 g bid,and clarithromycin 500 mg bid for 7 (OAC7) or 14 (OAC14) d. Primary outcome was eradication rate 6 wk after the treatment. Subgroup analysis was carried out considering the eradication rate among patients with or without peptic ulcer disease and eradication rate among smokers or non-smokers. RESULTS:One hundred and thirty-one patients were randomized to OAC7 (n = 69) or OAC14 (n = 62). The overall eradication rate (intention-to-treat) was 78.3% in OAC7 and 85.5% in OAC14 groups,without a significant difference (P =0.37). No significant difference in the eradication rate was found among the patients with peptic ulcer disease (n = 31) between the OAC7 group (85.7%) and OAC14 group (87.5%). However,smokers had an obviously lower eradication rate compared to non-smokers,particularly in the OAC7 group (57.1% in smokers vs 83.6% in non-smokers; P = 0.06). Adverse effects rate were similar between both groups. CONCLUSION:Short-term efficacy of triple therapy with OAC for 7 d is comparable to 14 d in this high-prevalence population. Longer follow-up,and studies focused to some subgroups of patients (smokers and non-ulcerpatients) are necessary to support widespread use of 7-d instead of 10-14-d triple therapy in a developing country like Chile.

关键词： Helicobacter pylori Antibiotic treatment Omeprazole Amoxicillin Clarithromycin Quasirandomized controlled trial

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Electrochemical Corrosion Study in H₂SO₄ of NiAl with Cu Additions, Microstructure and Micro-Hardness at Room Temperature

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Journal of Minerals and Materials Characterization and Engineering 2022年第3期10卷 225-241页

作者： Jesús M. Colín de la Cruz Sergio A. Serna Barquera Alvaro Torres-Islas Arturo Molina-Ocampo Edgar valenzuela josé G. González Rodríguez Universidad Autónoma del Estado de Morelos Facultad de Ciencias Químicas e Ingeniería UAEM-FCQeI. Av. Universidad 1001Colonia Chamilpa Cuernavaca Morelos México Universidad Autónoma del Estado de Morelos Centro de Investigación en Ingeniería y Ciencias Aplicadas UAEM-CIICAp Cuernavaca Morelos México UABC Baja California Sur México

For many years, intermetallic materials promise applications in a wide variety of technology areas. NiAl intermetallic compound is material that exhibits important characteristics such as high corrosion resistance and low density besides its ability to retain strength and stiffness at elevated temperatures. However NiAl intermetallic is too hard, brittle and exhibits very low ductility at room temperature being the reason because this material is not yet available for structural applications. In order to increase the ductility of the NiAl intermetallic compound, the addition of a third alloying element has been proved, nevertheless it is important to determine if such additions decrease or increase the hardness and the corrosion resistance of the alloy. So, the present investigation reports the corrosion performance of the NiAl intermetallic compound modified with Cu, emphasizing the EIS analysis and the relation between physical parameters and the modelling equations used in the Equivalent Electric Circuit. It was found that the addition of Cu promotes the formation of the γ’-Ni3Al phase in Cu contents greater than 15 at. %, in addition to a decrease in micro hardness and an increment in the Icorr values. In this way, the electrochemical characterization evidenced a high corrosion resistance of these intermetallic alloys.

关键词： NiAl-Cu Corrosion Behavior Electrochemical Impedance Spectrum Vickers Micro Hardness Microstructure

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