Montmorillonite clay intercalated with nanoparticles for hydrogen storage

Fabiola Campos,Luis de la Torre,Manuel Román,A. García,A. Aguilar Elguézabal 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.5

According to the expectations around the world concerning future of energy sources, hydrogen will be in a few years the most important energy carrier for stationary and mobile applications. Hydrogen storage is the bottleneck on the race to commercialize technologies based on the use of hydrogen, and specifically for mobile applications, the research goal for 2010 is to develop a device with at least 6% w/w of storage capacity. Highly porous carbon-based materials are among the most promising materials, with Carbon Molecular Sieves CMS) and Carbon Nanotubes (CNT) the most studied. In both cases materials are structured in such a way that hydrogen must diffuse along channels (micropores) where walls represent a restriction for the adsorption/desorption cycle. In this study, an alternative material is prepared by separation of clay layers with silica nanoparticles of diameter around 12 nm. The hydrogen storage capacity increased from 0.12 for untreated clay to 0.40% w/w for nanoassembled clay, measured at 77 K and atmospheric pressure, and according to intercalated clay characterization, almost all the surface available on the clay was exposed for adsorption. According to the expectations around the world concerning future of energy sources, hydrogen will be in a few years the most important energy carrier for stationary and mobile applications. Hydrogen storage is the bottleneck on the race to commercialize technologies based on the use of hydrogen, and specifically for mobile applications, the research goal for 2010 is to develop a device with at least 6% w/w of storage capacity. Highly porous carbon-based materials are among the most promising materials, with Carbon Molecular Sieves CMS) and Carbon Nanotubes (CNT) the most studied. In both cases materials are structured in such a way that hydrogen must diffuse along channels (micropores) where walls represent a restriction for the adsorption/desorption cycle. In this study, an alternative material is prepared by separation of clay layers with silica nanoparticles of diameter around 12 nm. The hydrogen storage capacity increased from 0.12 for untreated clay to 0.40% w/w for nanoassembled clay, measured at 77 K and atmospheric pressure, and according to intercalated clay characterization, almost all the surface available on the clay was exposed for adsorption.

Short-term outcomes in patients undergoing laparoscopic surgery for deep infiltrative endometriosis with rectal involvement: a single-center experience of 168 cases

Casas Sara Gortázar de las,Spagnolo Emanuela,Saverio Salomone Di,Álvarez-Gallego Mario,Carrasco Ana López,López María Carbonell,Cobos Sergio Torres,Campo Constantino Fondevila,Gutiérrez Alicia Hernánd 대한대장항문학회 2023 Annals of Coloproctolgy Vol.39 No.3

Purpose: The surgical management of deep infiltrative endometriosis (DE) involving the rectum remains a challenge. The objective of this study was to assess the outcomes from a single tertiary center over a decade with an emphasis on the role of a protective loop ileostomy (PI).Methods: A retrospective review of outcomes for 168 patients managed between 2008 and 2018 is presented including 57 rectal shaves, 23 discoid excisions, and 88 segmental rectal resections.Results: The nodule size (mean±standard deviation) in the segmental resection group was 32.7±11.2 mm, 23.4±10.5 mm for discoid excision, and 18.8±6.0 mm for rectal shaves. A PI was performed in 19 elective cases (11.3%) usually for an ultra-low anastomosis <5 cm from the anal verge. All Clavien-Dindo grade III/IV complications occurred after segmental resections and included 5 anastomotic leaks, 6 rectovaginal fistulas, 2 ureteric fistulas, and 1 ureteric stenosis. Of 26 stomas (15.5%), there were 19 PIs, 3 secondary ileostomies (after complications), and 4 end colostomies. The median time to PI closure was 5.8 months (range, 0.4–16.7 months) in uncomplicated disease compared with 9.2 months (range, 4.7–18.4 months) when initial postoperative complications were recorded (P=0.019). Only 1 patient with a recurrent rectovaginal fistula had a permanent colostomy.Conclusion: In patients with DE and rectal involvement a PI is selectively used for low anastomoses and complex pelvic reconstructions. Protective stomas and those used in the definitive management of a major postoperative complication can usually be reversed.

A facile route to ketene-functionalized polymers for general materials applications

Leibfarth, Frank A.,Kang, Minhyuk,Ham, Myungsoo,Kim, Joohee,Campos, Luis M.,Gupta, Nalini,Moon, Bongjin,Hawker, Craig J. Nature Publishing Group 2010 Nature chemistry Vol.2 No.3

Function matters in materials science, and methodologies that provide paths to multiple functionality in a single step are to be prized. Therefore, we introduce a robust and efficient strategy for exploiting the versatile reactivity of ketenes in polymer chemistry. New monomers for both radical and ring-opening metathesis polymerization have been developed, which take advantage of Meldrum's acid as both a synthetic building block and a thermolytic precursor to dialkyl ketenes. The ketene-functionalized polymers are directly detected by their characteristic infrared absorption and are found to be stable under ambient conditions. The inherent ability of ketenes to provide crosslinking via dimerization and to act as reactive chemical handles via addition, provides simple methodology for application in complex materials challenges. Such versatile characteristics are illustrated by covalently attaching and patterning a dye through microcontact printing. The strategy highlights the significant opportunities afforded by the traditionally neglected ketene functional group in polymer chemistry.

Modelling the Hydrogen-Bonding Interactions in a Copolymer/Biodegradable Homopolymer Blend through Excess Functions

Rosa Garc’a-Lopera,Isidro S. Monzó,Agust’n Campos,Concepci—n Abad 한국고분자학회 2008 Macromolecular Research Vol.16 No.5

A recent theoretical approach based on the coupling of both the Flory-Huggins (FH) and the Association Equilibria thermodynamic (AET) theories was modified and adapted to study the miscibility properties of a multi-component system formed by two polymers (a proton-donor and a proton-acceptor) and a proton-acceptor solvent, named copolymer(A)/solvent(B)/polymer(C). Compatibility between polymers was mainly attained by hydrogen-bonding between the hydroxyl group on the phenol unit of the poly(styrene-co-vinyl phenol) (PSVPh) and the carbonyl group of the biodegradable and environmentally friendly poly(3-hydroxybutyrate) (PHB). However, the self-association of PSVPh and specific interactions between the PSVPh and the H-acceptor group (an ether oxygen atom) of the epichlorohydrin (ECH) solvent were also established in a lower extension, which competed with the polymer-polymer association. All the binary specific interactions and their dependence with the system composition as well as with the copolymer content were evaluated and quantified by means of two excess functions of the Gibbs free energy, ΔgAB and ΔgAC. Experimental results from fluorescence spectroscopy were consistent with the theoretical simulations derived with the model, which could also be applied and extended to predict the miscibility in solution of any polymer blend with specific interactions.

A Girl with 15q Overgrowth Syndrome and dup(15)(q24q26.3) that Included Telomeric Sequences

María de los Ángeles Gutiérrez-Franco,María de la Luz Madariaga-Campos,Ana I. Vásquez-Velásquez,Esmeralda Matute,Roberto Guevara-Yáñez,Horacio Rivera 대한진단검사의학회 2010 Annals of Laboratory Medicine Vol.30 No.3

Distal 15q trisomy or tetrasomy is associated with a characteristic phenotype that includes mild to moderate intellectual disability, abnormal behavior, speech impairment, overgrowth, hyperlaxity, long face, prominent nose, puffy cheeks, pointed chin, small ears, and hand anomalies (mainly arachno- and camptodactyly). We present the case of a 13-yr-old girl with the main clinical features of 15q overgrowth syndrome and a 46,XX,dup(15)(q24q26.3)[117]/46,XX[3].ish dup(15)(q24q26.3) (SNPRN+,PML+,subtel++,tel++) de novo karyotype. The findings in this case are consistent with those in the previous distal 15q trisomy cases that presented with overgrowth and mental retardation. Further, the rearranged chromosome had a double set of directly oriented telomeric and subtelomeric sequences. (Korean J Lab Med 2010;30:318-24)

A nonlinear controller based on saturation functions with variable parameters to stabilize an AUV

E. Campos,J. Monroy,H. Abundis,A. Chemori,V. Creuze,J. Torres 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

This paper deals with a nonlinear controller based on saturation functions with variable parameters for set-point regulation and trajectory tracking control of an Autonomous Underwater Vehicle (AUV). In many cases, saturation functions with constant parameters are used to limit the input signals generated by a classical PD (Proportional-Derivative) controller to avoid damaging the actuators; however this abrupt bounded harms the performance of the controller. We, therefore, propose to replace the conventional saturation function, with constant parameters, by a saturation function with variable parameters to limit the signals of a PD controller, which is the base of the nonlinear PD with gravitational/ buoyancy compensation and the nonlinear PD þ controllers that we propose in this paper. Consequently, the mathematical model is obtained, considering the featuring operation of the underwater vehicle LIRMIA 2, to do the stability analysis of the closed-loop system with the proposed nonlinear controllers using the Lyapunov arguments. The experimental results show the performance of an AUV (LIRMIA 2) for the depth control problems in the case of set-point regulation and trajectory tracking control.

A D-Band Subharmonically-Pumped Resistive Mixer Based on a 100 nm MHEMT Technology

Y. Campos-Roca,A. Tessmann,H. Massler,A. Leuther 한국전자통신연구원 2011 ETRI Journal Vol.33 No.5

A D-band subharmonically-pumped resistive mixer has been designed, processed, and experimentally tested. The circuit is based on a 180-degree power divider structure consisting of a Lange coupler followed by a lambda/4 transmission line (at local oscillator (LO) frequency). This monolithic microwave integrated circuit (MMIC) has been realized in coplanar waveguide technology by using an InAlAs/InGaAs-based metamorphic high electron mobility transistor process with 100-nm gate length. The MMIC achieves a measured conversion loss between 12.5 dB and 16 dB in the radio frequency bandwidth from 120 GHz to 150 GHz with 4-dBm LO drive and an intermediate frequency of 100 MHz. The input 1-dB compression point and IIP3 were simulated to be 2 dBm and 13 dBm, respectively.

A nonlinear controller based on saturation functions with variable parameters to stabilize an AUV

Campos, E.,Monroy, J.,Abundis, H.,Chemori, A.,Creuze, V.,Torres, J. The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

This paper deals with a nonlinear controller based on saturation functions with variable parameters for set-point regulation and trajectory tracking control of an Autonomous Underwater Vehicle (AUV). In many cases, saturation functions with constant parameters are used to limit the input signals generated by a classical PD (Proportional-Derivative) controller to avoid damaging the actuators; however this abrupt bounded harms the performance of the controller. We, therefore, propose to replace the conventional saturation function, with constant parameters, by a saturation function with variable parameters to limit the signals of a PD controller, which is the base of the nonlinear PD with gravitational/buoyancy compensation and the nonlinear PD + controllers that we propose in this paper. Consequently, the mathematical model is obtained, considering the featuring operation of the underwater vehicle LIRMIA 2, to do the stability analysis of the closed-loop system with the proposed nonlinear controllers using the Lyapunov arguments. The experimental results show the performance of an AUV (LIRMIA 2) for the depth control problems in the case of set-point regulation and trajectory tracking control.

Application of Bonelike® as synthetic bone graft in orthopaedic and oral surgery in veterinary clinical cases.

José Miguel Campos,Ana Catarina Sousa,Pedro Olivério Pinto,Jorge Ribeiro,Miguel Lacueva França,Ana Rita Caseiro,Mariana Vieira Branquinho,Sílvia Santos Pedrosa,Carla Mendonça,Ana Brandão,José Domingos 한국생체재료학회 2019 생체재료학회지 Vol.23 No.1

Autologous bone remains the gold standard grafting substrate for bone fusions used for small gaps and critical defects. However, significant morbidity is associated with the harvesting of autologous bone grafts and, for that reason, alternative bone graft substitutes have been developed. In the present case series, a glass-reinforced hydroxyapatite synthetic bone substitute, with osteoinductive and osteoconductive proprieties, was applied. This synthetic bone substitute comprises the incorporation of P2O5-CaO glass-based system within a hydroxyapatite matrix, moulded into spherical pellets with 250-500 μm of diameter. A total of 14 veterinary clinical cases of appendicular bone defects and maxillary / mandibular bone defects are described. In all clinical cases, the synthetic bone substitute was used to fill bone defects, enhancing bone regeneration and complementing the recommended surgical techniques. Results demonstrated that it is an appropriate synthetic bone graft available to be used in veterinary patients. It functioned as a space filler in association with standard orthopaedic and odontological procedures of stabilization, promoting a faster bone fusion without any local or systemic adverse reactions. This procedure improves the animals’ quality of life, decreasing pain and post-operative recovery period, as well as increasing bone stability improving positive clinical outcomes.

Characterization of Escherichia coli EutD: a Phosphotransacetylase of the Ethanolamine Operon

Federico P. Bologna,Valeria A. Campos-Bermudez,Damián D. Saavedra,Carlos S. Andreo,María F. Drincovich 한국미생물학회 2010 The journal of microbiology Vol.48 No.5

The Escherichia coli genes pta and eutD encode proteins containing the phosphate-acetyltransferase domain. EutD is composed only by this domain and belongs to the ethanolamine operon. This enzyme has not been characterized yet, and its relationship to the multimodular E. coli phosphotransacetylase (Pta) remains unclear. In the present work, a detailed characterization of EutD from E. coli (EcEutD) was performed. The enzyme is a more efficient phosphotransacetylase than E. coli Pta (EcPta) in catalyzing its reaction in either direction and assembles as a dimer, being differentially modulated by EcPta effectors. When comparing EutD and Pta, both from E. coli, certain divergent regions of the primary structure responsible for their unique properties can be found. The growth on acetate of the E. coli pta acs double-mutant strain, was complemented by either introducing EcEutD or by inducing the eut operon with ethanolamine. In this case, the expression of a phosphotransacetylase different from Pta was confirmed by activity assays. Overall, the results indicate that EcEutD and Pta, although able to catalyse the same reaction, display differential efficiency and regulation, and also differ in the induction of their expression. However, under certain growth conditions, they can fulfil equal roles in E. coli metabolism.