Time filter

Source Type

Garcia-Valles M.,University of Barcelona | Alfonso P.,Polytechnic University of Catalonia | Arancibia J.R.H.,Technical University of Oruro | Martinez S.,University of Barcelona | Parcerisa D.,Polytechnic University of Catalonia
Journal of Thermal Analysis and Calorimetry | Year: 2015

Large volumes of borate resources exist in Bolivia, with the most important being the Rio Grande deposit, located close to the Salar of Uyuni. Here, borates occur in beds and lenses of variable thickness. A mineralogical and thermal characterization of borates from the Rio Grande was made using XRD, FTIR, SEM and DTA–TG. The deposit is mainly composed of B2O3, CaO and Na2O, with minor contents of MgO and K2O. Some outcrops are constituted by pure ulexite aggregates (NaCaB5O6(OH)6·5H2O) of fibrous morphology; in other cases, gypsum, calcite and halite also are present. The thermal decomposition of ulexite begins at 70 °C and proceeds up to ~550 °C; this decomposition is attributed to dehydration and dehydroxylation processes in three steps: at 115, 150–300 and 300–550 °C. The last mass loss of 1–5 % at 800 °C is due to the removal of Cl2 from the decomposition of halite. DTA shows two endothermic events related to the removal of water; in the first, NaCaB5O6(OH)6·5H2O evolved from NaCaB5O6(OH)6·3H2O, at 108–116 °C; in the second, NaCaB5O6(OH)6 is formed at 180–185 °C and NaCaB5O9 (amorphous) is formed at 300–550 °C. The exothermic peak (658–720 °C) is related to the crystallization of NaCaB5O9. A small endothermic peak appears due to the halite melting. Later, another endothermic event (821–877 °C) appears, which is related to the decomposition of NaCaB5O9 into a crystalline phase of CaB2O4 and amorphous NaB3O5. The XRD pattern evidences that, at 1050 °C, CaB2O4 still remains in the crystalline state. © 2015 Akadémiai Kiadó, Budapest, Hungary

Alagon G.,National University San Antonio Abad del Cusco | Arce O.,Technical University of Oruro | Serrano P.,Research Center y Tecnologia Animal | Rodenas L.,Polytechnic University of Valencia | And 4 more authors.
Meat Science | Year: 2015

The effect of dietary inclusion of distillers dried grains with solubles (DDGS) on carcass and meat quality of longissimus muscle was studied in 100 growing rabbits from 28 to 59. days old. Diets with no DDGS (C), barley (Db20), wheat (Dw20) and corn (Dc20) DDGS at 20% and corn (Dc40) DDGS at 40% were formulated. No effects on most of the carcass traits, texture and water holding capacity were found. Barley and corn DDGS led to a higher dissectible fat percentage. Meat redness was higher with Dw20 and pH was higher with Dw20 and Db20 than with Dc20. Protein and saturated fatty acids concentration declined as corn DDGS level increased. Dc40 led to the lowest saturated/unsaturated fatty acid ratio, atherogenic index and thrombogenic index. In conclusion, dietary inclusion of these DDGS at 20% did not affect most of the carcass and meat quality traits in rabbits. © 2014 Elsevier Ltd.

Arancibia J.R.H.,Technical University of Oruro | Alfonso P.,Polytechnic University of Catalonia | Garcia-Valles M.,University of Barcelona | Martinez S.,University of Barcelona | And 3 more authors.
Boletin de la Sociedad Espanola de Ceramica y Vidrio | Year: 2013

Tailings from mining activities in Bolivia represent an environmental problem. In the vicinity of the tin mines of Llallagua, Potosí department, there are large dumps and tailings. We present a study of the use of these wastes as raw materials for the manufacture of glass. This procedure aims to contribute to environmental remediation of mining areas through the vitrification, a process which offers an alternative for stabilization of hazardous waste. In addition, the marketing of the obtained product would provide an additional income to the mining areas. For this study three samples of mining waste, with grain size between sand and silt, were used. The chemical composition of these raw materials, determined by X-ray fluorescence, is granitic, with high contents of heavy metals. On the basis of its composition, glass were made from silica glass by adding CaCO3 and Na 2CO3. The thermal cycle has been determined from TDA. Tg values of glass range from 626° to 709 °C. Leaching tests of the obtained glasses confirm their capacity to retain heavy metals.

Barreta J.,Institute Biologia Molecular y Biotecnologia | Barreta J.,University of León | Iniguez V.,Institute Biologia Molecular y Biotecnologia | Saavedra V.,Technical University of Oruro | And 5 more authors.
Small Ruminant Research | Year: 2012

We have examined the genetic diversity and population structure of 149 Bolivian alpacas from eight different locations in Bolivia. The analysis of 22 microsatellite loci revealed high levels of genetic diversity, similar to the results reported in other alpaca populations. This high genetic variability was sustained by the identification of a total of 258 alleles; we identified between 4 and 18 alleles per locus with high levels of observed heterozygosity that ranged from 0.611 to 0.696. The inbreeding coefficients (Fis) were positive and significantly different from zero for all of the populations except for Turco. The genetic differentiation between populations (Fst) was low to moderate with pair-wise Fst estimates ranging from 0.008 for the Curahuara-Cosapa pair, to 0.077 for the Poopó-Ayopaya and Poopó-Ulla Ulla pairs. The analysis of molecular variance (AMOVA) indicated that the total variability observed between different populations was 3.86%, whereas 96.14% of the variation was found within the populations. The population structure analysis revealed that the eight studied populations could be assigned to five differentiated clusters. In agreement with the factorial analysis of correspondence, and supported through a bootstrapping analysis to adjust for differences in population sample size, this analysis suggested a genetic isolation of the Poopó population and the influence of the Turco population on the populations linked to the Cochabamba and the Pacajes-Sajama alpaquero systems. The Ulla Ulla population showed a clear subdivision into two clusters; in addition, these two clusters had an influence on the Challapata population and less impact on the rest of the populations. The Cosapa, Lagunas and Curahuara populations showed a clear common genetic background, whereas the Ayopaya population was influenced by the five defined clusters. Despite some sampling limitations and the need of confirming the results reported here through larger datasets, overall, this study provides the first survey of the genetic diversity in Bolivian alpaca populations, which may be of great value for the development of appropriate breeding strategies for these populations. © 2012 Elsevier B.V.

Alagon G.,National University San Antonio Abad del Cusco | Arce O.N.,Technical University of Oruro | Martinez-Paredes E.,Polytechnic University of Valencia | Rodenas L.,Polytechnic University of Valencia | And 2 more authors.
World Rabbit Science | Year: 2014

To evaluate how dietary inclusion of distillers dried grains and solubles (DDGS) could affect the performance and caecal environment of growing rabbits, four experimental diets were formulated from a control diet without DDGS (C), including 20% barley DDGS (Db20), 20% wheat DDGS (Dw20) and 20 (Dc20) or 40% (Dc20) corn DDGS. Animals had free access to medicated versions of the diets until 49 d, and then to unmedicated diets until 59 d of age. The performance trial was done using 475 three-way crossbred weaned rabbits of 28 d of age, individually housed in 5 batches. Caecal fermentation traits were determined in 20 animals per diet and at 42 d and at 59 d of age. No significant effect of the growing diet on mortality, morbidity or sanitary risk index was observed. In the whole period and compared to the control group, animals fed with Db20showed higher dry matter (DM) and digestible energy (DE) intake (+6 and +12%, respectively; P<0.05), but similar daily weight gain (DWG) and increased feed conversion ratio (+9%; P<0.05). Similarly, and regardless of its inclusion level, the increase in DE intake of animals fed with corn DDGS (+9, respectively; P<0.05) did not increase DWG. In contrast, higher DM and DE intake of animals fed with Dw20(+8; P<0.05) resulted in a higher DWG (+2.8 g/d; P<0.05) than those fed with C. Although inclusion of DDGS at 20% did not affect main caecal parameters recorded at 42 d, caecum of animals fed with the diet Dc40was characterised by greater N-NH3and valeric acid and lower total volatile fatty acids and acetic acid concentrations than the average of the other groups (on av. +5.2±1.7 mmol/L, +0.29±0.07 mol/100 mol, -17.17±4.41 μmol/L and -2.60±0.99 mol/100 mol, respectively; P<0.05). At 59 d of age, higher caecal DM, and propionic and valeric acid concentration and lower values of total volatile fatty acids and acetic/propionic rate were observed for DDGS inclusion at 20% compared to the control (+1.6±0.5%, +0.95±0.44 mol/100 mol, -9.3±4.3 μmol/L and -2.7±1.2, respectively; P<0.05). Linear inclusion of corn DDGS increased caecal DM, propionic acid proportion and total volatile fatty acids concentration and reduced acetate/propionic rate (+4.0±0.4%, +2.27±0.41 mol/100 mol, -21.27±3.9 μmol/L and -5.6±1.1, respectively for Dc40compared to C; P<0.05). Rabbits given Dc40were also characterised for a greater caecum N-NH3 content than the other groups (on av. -8.7±1.7 mmol/L; P<0.05) at 59 d of age. The results of the present work reveal that inclusion of DDGS up to 20%, independently of the grain source (barley, wheat or corn), could be an interesting alternative in balanced diets for growing rabbits. © WRSA, UPV, 2003.

Van Den Bergh K.,University of Antwerp | Du Laing G.,Ghent University | Montoya J.C.,Technical University of Oruro | De Deckere E.,University of Antwerp | Tack F.M.G.,Ghent University
Journal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering | Year: 2010

In the rural areas around Oruro (Bolivia), untreated groundwater is used directly as drinking water. This research aimed to evaluate the general drinking water quality, with focus on arsenic (As) concentrations, based on analysis of 67 samples from about 16 communities of the Oruro district. Subsequently a filter using Iron Oxide Coated Sand (IOCS) and a filter using a Composite Iron Matrix (CIM) were tested for their arsenic removal capacity using synthetic water mimicking real groundwater. Heavy metal concentrations in the sampled drinking water barely exceeded WHO guidelines. Arsenic concentrations reached values up to 964 μg L-1 and exceeded the current WHO provisional guideline value of 10 μg L-1 in more than 50% of the sampled wells. The WHO guideline of 250 mg L-1 for chloride and sulphate was also exceeded in more than a third of the samples, indicating high salinity in the drinking waters. Synthetic drinking water could be treated effectively by the IOCS- and CIM-based filters reducing As to concentrations lower than 10 μg L -1. High levels of chloride and sulphate did not influence As removal efficiency. However, phosphate concentrations in the range from 4 to 24 mg L-1 drastically decreased removal efficiency of the IOCS-based filter but had no effects on removal efficiency of the CIM-based filter. Results of this study can be used as a base for further testing and practical implementation of drinking water purification in the Oruro region. Copyright © Taylor & Francis Group, LLC.

Barreta J.,University of León | Barreta J.,Institute Biologia Molecular y Biotecnologia | Gutierrez-Gil B.,University of León | Iniguez V.,Institute Biologia Molecular y Biotecnologia | And 5 more authors.
Journal of Animal Breeding and Genetics | Year: 2013

South American camelids (SACs) have a major role in the maintenance and potential future of rural Andean human populations. More than 60% of the 3.7 million llamas living worldwide are found in Bolivia. Due to the lack of studies focusing on genetic diversity in Bolivian llamas, this analysis investigates both the genetic diversity and structure of 12 regional groups of llamas that span the greater part of the range of distribution for this species in Bolivia. The analysis of 42 microsatellite markers in the considered regional groups showed that, in general, there were high levels of polymorphism (a total of 506 detected alleles; average PIC across per marker: 0.66), which are comparable with those reported for other populations of domestic SACs. The estimated diversity parameters indicated that there was high intrapopulational genetic variation (average number of alleles and average expected heterozygosity per marker: 12.04 and 0.68, respectively) and weak genetic differentiation among populations (FST range: 0.003-0.052). In agreement with these estimates, Bolivian llamas showed a weak genetic structure and an intense gene flow between all the studied regional groups, which is due to the exchange of reproductive males between the different flocks. Interestingly, the groups for which the largest pairwise FST estimates were observed, Sud Lípez and Nor Lípez, showed a certain level of genetic differentiation that is probably due to the pattern of geographic isolation and limited communication infrastructures of these southern localities. Overall, the population parameters reported here may serve as a reference when establishing conservation policies that address Bolivian llama populations. © 2012 Blackwell Verlag GmbH.

Barreta J.,University of León | Barreta J.,Higher University of San Andrés | Gutierrez-Gil B.,University of León | Iniguez V.,Higher University of San Andrés | And 4 more authors.
Animal Genetics | Year: 2013

The objectives of this work were to assess the mtDNA diversity of Bolivian South American camelid (SAC) populations and to shed light on the evolutionary relationships between the Bolivian camelids and other populations of SACs. We have analysed two different mtDNA regions: the complete coding region of the MT-CYB gene and 513 bp of the D-loop region. The populations sampled included Bolivian llamas, alpacas and vicunas, and Chilean guanacos. High levels of genetic diversity were observed in the studied populations. In general, MT-CYB was more variable than D-loop. On a species level, the vicunas showed the lowest genetic variability, followed by the guanacos, alpacas and llamas. Phylogenetic analyses performed by including additional available mtDNA sequences from the studied species confirmed the existence of the two monophyletic clades previously described by other authors for guanacos (G) and vicunas (V). Significant levels of mtDNA hybridization were found in the domestic species. Our sequence analyses revealed significant sequence divergence within clade G, and some of the Bolivian llamas grouped with the majority of the southern guanacos. This finding supports the existence of more than the one llama domestication centre in South America previously suggested on the basis of archaeozoological evidence. Additionally, analysis of D-loop sequences revealed two new matrilineal lineages that are distinct from the previously reported G and V clades. The results presented here represent the first report on the population structure and genetic variability of Bolivian camelids and may help to elucidate the complex and dynamic domestication process of SAC populations. © 2012 The Authors.

Yave W.,Helmholtz Center Geesthacht | Szymczyk A.,West Pomeranian University of Technology | Yave N.,Technical University of Oruro | Roslaniec Z.,West Pomeranian University of Technology
Journal of Membrane Science | Year: 2010

The design and synthesis of polymers with well-defined properties (tailor-made) are reported in this paper. The work focuses on the design of experiments, synthesis and characterization of poly(trimethylene terephthalate)-block-poly(ethylene oxide) (PTT-b-PEO) copolymers as CO2-philic membrane materials. The statistical analysis of experimental data, data fitting to mathematical models, as well as the optimization of CO2 permeability is discussed. By these means we synthesized optimal materials with promising CO2 separation performance (CO2 permeability=183-200Barrer and CO2/N2 selectivity >50); they are also promising because the synthesis is simple, highly reproducible and might be scalable for producing on large volumes. Thus, these new and tailored polymers might have potential applications as membrane material for CO2-capture. © 2010 Elsevier B.V.

News Article | February 21, 2017
Site: www.marketwired.com

TORONTO, CANADA--(Marketwired - Feb. 21, 2017) - BacTech Environmental Corporation ("BacTech" or the "Company"), (CSE:BAC) (OTC PINK:BCCEF) today announced the results of the first 47 samples (35 routines and 12 control samples) from 3 holes drilled on a 60-hole drill program (approximately 600 m in total) at the Company's joint venture Silver- Copper-Tin tailings remediation project at Telamayu, Bolivia. The purpose of the program is to verify earlier work carried out by BacTech's partner, Mining Corporation of Bolivia ("COMIBOL"), the Bolivian state mining company, and to provide material for upcoming metallurgical work. Additional results will be released in batches over the next few weeks. Telamayu is an historic mill town situated next to Atocha, Bolivia. Over the past 80 years, the mill has treated material from 2 local mines (Tasna and Animas). The tailings from the mill make up the Antigua tailings, the subject of these assays, and the much larger Nuevo tailings. Previously, COMIBOL engaged individuals to dig test holes on the tailings (five wells of 1.5mx 1.5mx10m) with bulk samples taken every meter as well as channel samples. The test holes showed a tin grade of 0.97% and a silver content of 408 g/t. Upon completion of the execution of the contract with COMIBOL for the remediation and exploitation of the old tailings of Telamayu, which was subsequently approved by the Bolivian Congress and endorsed by an express law, BacTech had access to documents that COMIBOL's Environment Department had prepared in 2004-2005. These documents present a proposal for the exploitation of the "old tailings dam of Telamayu". Specifically, the documents deal with work to be carried out for the evaluation of the dam's potential, the technical options for metal extraction, the proposed type of plant to be employed and an estimate of the project's profitability. The historical data and grades presented above are relevant to the further exploration of the project, which the Company is currently undertaking with a drill program. BacTech is conducting a tailing evaluation program with approximately 60 holes to be drilled with the Vibracore system with systematic core sampling meter by meter. At present, 65% of the drilling program has been completed and approximately 600 core samples were sent in for chemical analysis. The results from the 3 first holes are as follows (weighted average, uncut): Admittedly, only 8% of the material has been assayed to date, but these values have exceeded our expectations. Samples consist of half NQ-size diamond core that are split on site, prepared at the Spectrolab laboratory, an ISO accredited laboratory at the Technical University of Oruro, Bolivia and assayed for gold, silver, tin and copper by fire assay for silver and by Atomic absorption or total fusion for the base metals. The QA-QC program of the Company includes insertion of certified standards every 20 samples, blanks at least every 20 samples and core duplicates every 20 samples. The remaining half core is retained onsite for verification and reference purposes. The sampling results from this drill program will be the underpinning of a resource estimation following the guidelines established by Canadian National Instrument 43-101 reporting. Once the drilling program has been completed, the Company will immediately begin metallurgical test work to determine the appropriate method for metal recovery. A complete NI 43-101 Preliminary Economic Assessment ("PEA") will then be completed. "It was a bit tricky in the beginning of the drill program as we discovered a cement-like layer up to 1 meter thick that the Vibracore had a hard time getting through. Alterations were made to the program and, at the time of writing, we are in the final stages of the program," said Ross Orr, President and CEO of BacTech. Kamil Khobzi, an engineer and Qualified Person under NI 43-101, who has visited the property, has read and approved this release. Finally, the Company also announced that it has closed a CAD$30,000 tranche of the current financing. The financing is a 5-cent unit consisting of 1 common share of the Company and 1/2 (one half) of a common share purchase warrant. One full warrant plus 10 cents buys an additional common share for 2 years from the closing of this tranche. BacTech Environmental Corporation holds the perpetual, exclusive, royalty-free rights to use the patented BACOX bioleaching technology for the reclamation of tailings and mining waste materials. The Company's principal focus is a high-grade silver/copper/tin tailings project called Telamayu, located in Atocha, Bolivia, in association with COMIBOL, the state mining group. Investigation has begun to identify opportunities in Ecuador. The Company continues to field enquiries globally with respect to additional opportunities for remediation, including licensing transactions for the technology. This news release contains "forward-looking information", which may include, but is not limited to, statements with respect to future tailings sites, sampling or other investigations of tailing sites, the Company's ability to make use of infrastructure around tailings sites or operating performance of the Company and its projects. Often, but not always, forward-looking statements can be identified by the use of words such as "plans", "expects", "is expected", "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates", or believes" or variations (including negative variations) of such words and phrases, or state that certain actions, events or results "may", "could", "would", "might" or "will" be taken, occur or be achieved. Forward-looking statements involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of the Company to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Forward-looking statements contained herein are made as of the date of this news release and the Company disclaims, other than as required by law, any obligation to update any forward-looking statements whether as a result of new information, results, future events, circumstances, or if management's estimates or opinions should change, or otherwise. There can be no assurance that forward-looking statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, the reader is cautioned not to place undue reliance on forward-looking statements. The Canadian Securities Exchange (CSE) has not reviewed and does not accept responsibility for the adequacy or the accuracy of the contents of this release.

Loading Technical University of Oruro collaborators
Loading Technical University of Oruro collaborators