163 research outputs found
Miniaturization of Planar Microwave Devices by Means of Complementary Spiral Resonators (CSRs): Design of Quadrature Phase Shifters
In this work, two compact quadrature phase shifters based on metamaterial transmission lines implemented by means of complementary spiral resonators (CSRs) have been designed, fabricated and measured. The structures consist on Y-junctions with output lines exhibiting 90º phase balance. The reported metamaterial-based devices present a size reduction of 64% and 77% as compared to the conventional one
High prevalence of scrapie in a dairy goat herd: tissue distribution of disease-associated PrP and effect of PRNP genotype and age
Following a severe outbreak of clinical scrapie in 2006–2007, a
large dairy goat herd was culled
and 200 animals were selected for post-mortem examinations in order to
ascertain the prevalence of infection,
the effect of age, breed and PRNP genotype on the susceptibility to scrapie,
the tissue distribution of diseaseassociated
PrP (PrP), and the comparative efficiency of different diagnostic methods.
As determined by immunohistochemical (IHC) examinations with Bar224 PrP antibody, the
prevalence of preclinical infection
was very high (72/200; 36.0%), with most infected animals being positive
for PrP in lymphoreticular system
(LRS) tissues (68/72; 94.4%) compared to those that were positive in
brain samples (38/72; 52.8%). The
retropharyngeal lymph node and the palatine tonsil showed the highest
frequency of PrP accumulation (87.3%
and 84.5%, respectively), while the recto-anal mucosa-associated lymphoid
tissue (RAMALT) was positive in
only 30 (41.7%) of the infected goats. However, the efficiency of rectal
and palatine tonsil biopsies taken
shortly before necropsy was similar. The probability of brain and RAMALT
being positive directly
correlated with the spread of PrP within the LRS. The prevalence of
infection was influenced by PRNP
genetics at codon 142 and by the age of the goats: methionine carriers older
than 60 months showed a much
lower prevalence of infection (12/78; 15.4%) than those younger than 60 months (20/42; 47.6%); these last
showed prevalence values similar to isoleucine homozygotes of any age
(40/80; 50.0%). Two of seven goats
with definite signs of scrapie were negative for PrP in brain but positive
in LRS tissues, and one goat showed
biochemical and IHC features of PrP different from all other infected
goats. The results of this study have
implications for surveillance and control policies for scrapie in goats
Enhancement of the bioproduction potential of an amylaceous effluent
9 páginas, 12 figuras, 4 tablasThe treatment of starchy effluents could provide the basis
for a series of simultaneous or alternative bioproductions
easily integrable into a system of greater economic
attraction that the simple production of SCP. In order to
define some of the possible options, this study uses an
amylaceous effluent for simultaneous production of SCP
and an amylolytic preparation which is partially consumed
in the saccharification of a parallel flow of the
same effluent concentrated by ultrafiltration with cutoff
at 100 kD.
With regard to the development of the above system,
this paper describes the problems associated with ultrafiltration,
the conditions that optimize saccharification
of the concentrate and the requirements of various possible
bioproductions that couM be obtained from the
saccharified concentrate.CICYT (project ALl 789-
9O).Peer reviewe
Oxygen reduction reaction kinetics on a Pt thin layer electrode in AEMFC
The study of the catalytic activity in a fuel cell is challenging, as mass transport, gas crossover and the counter electrode are generally interfering. In this study, a Pt electrode consisting of a thin film deposited on the gas diffusion layer was employed to study the oxygen reduction reaction (ORR) in an operating Anion Exchange Membrane Fuel Cell (AEMFC). The 2D Pt electrode was assembled together with a conventional porous Pt/C counter electrode and an extra Pt/C layer and membrane to reduce the H2 crossover. Polarization curves at different O2 partial pressures were recorded and the resulting reproducible ORR activities were normalized with respect to the active surface area (ECSA), obtained by CO stripping. As expected, decreasing the O2 partial pressure results in a negative shift in open circuit voltage (OCV), cell voltage and maximum attainable current density. For cell voltages above 0.8 V a fairly constant Tafel slope of 60 mV dec−1 was recorded but at lower voltages the slope increases rapidly. The observed Tafel slope can be explained by a theoretical model with an associative mechanism where charge- and proton-transfer steps are decoupled, and the proton transfer is the rate-determining step. A reaction order of 1 with respect to O2 was obtained at 0.65 V which corresponds well with the mechanism suggested above. Based on the obtained catalyst activities, the electrode performance is comparable to good porous electrodes found in the field. The methodology presented in this study is expected to be useful in future kinetic studies of other catalysts for AEMFC
Objetivos de Desarrollo Sostenible y Aprendizaje Servicio en la docencia universitaria: un estudio de caso en el área de Biblioteconomía y Documentación
Las universidades se configuran como instituciones clave para responder activamente al cumplimiento de los Objetivos de Desarrollo Sostenible (ODS) de la “Agenda 2030” de la ONU. A pesar de que han surgido algunas iniciativas para responder a dicho reto, se constata la necesidad deincrementar las acciones que respondan a tal finalidad yque emerjandesde el ámbito universitario. A dicho enfoque se vincula el estudio de caso que se presenta. Se ha desarrollado una expe-riencia de docencia universitaria en el área de Bibliote-conomía y Documentación, sustentada en establecer una vinculación entre la metodología docente de Aprendizaje Servicio (ApS) y la incorporaciónde una perspectiva basada en los ODS en la formación de los futuros bibliotecarios, archiveros y documentalistas.
Universities are key institutions to respond to the achievement of the Sustainable Development Goals (SDGs) of the UN "2030 Agenda". Although some initiatives have emerged to respond to this challenge, more university actions and initiatives have to be taken. This research is a case study based on the approach mentioned. A teaching experience at university level has been developed in the Library and Information Science area to link the Service Learning (SL) methodology with an innovative teaching approach focused on the SDGs to improve librarians, archivists and information professionals training
Enhanced oxygen reduction activity with rare earth metal alloy catalysts in proton exchange membrane fuel cells
Alloying platinum is an approach to increase the oxygen reduction reaction (ORR) activity and at the same time reduce the amount of precious platinum catalyst in proton exchange membrane fuel cells (PEMFC). In this work the cathode activity of thin films of rare earth metals (REM) alloys, Pt Y, Pt Gd and Pt Tb, produced by sputter deposition onto gas diffusion layers, are evaluated in a fuel cell by means of polarization curves in O /H , and cyclic- and CO-stripping voltammetry in N /5% H . Prior to evaluation, the model electrodes were acid-treated to obtain a Pt skin covering the PtREM alloy bulk, as was revealed by energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The core shell alloys of Pt Y and Pt Gd catalysts show a specific activity enhancement at 0.9 V of 2.5 times compared to pure Pt. The slightly lower enhancement factor of 2.0 for Pt Tb is concluded to be due to leaching of the REM, that resulted in a thicker, and subsequently less strained, Pt overlayer. The high activity, combined with the minor changes in surface composition, achieved in the fuel cell environment shows that PtREM core shell catalysts are promising for the cathode reaction in PEMFC
Autoimmune congenital heart block and primary Sjogren's syndrome:characterisation and outcomes of 49 cases
Objective. To characterise autoimmune congenital heart block (CHB) associated with a maternal diagnosis of primary Sjogren's syndrome (pSS) confirmed either before, concomitant or after the first pregnancy complicated with CHB. Methods. The following inclusion criteria were applied: (i) Mothers with positive Ro/La autoantibodies detected previously or at the time of diagnosis of the first case of CHB; (ii) diagnosis of CHB confirmed by fetal echocardiography; (iii) AV block diagnosed in uterus, at birth or within the neonatal period (0-27 days after birth) (8); (iv) absence of anatomical cardiac abnormalities which might be causal of AV block; and (v) maternal fulfillment of the 2002 SS criteria before, during or after having a pregnancy complicated with CHB. Results. We identified 49 cases of autoimmune CHB in children born from 44 mothers who had a mean age at the time of pregnancy of 30.3 years (range 18 to 41). At the time of diagnosis of autoimmune CHB, all mothers had positive anti-Ro antibodies and 28/ 44 (64%) were positive for anti-La antibodies. Only 10 (22%) mothers with affected pregnancies had a diagnosis of primary SS at the time of diagnosis of the first pregnancy complicated by CHB (a mean of 4 years before, ranging from 1 to 10 years). In 6 (14%) mothers, primary SS was diagnosed during pregnancy or less than 12 months after the delivery/termination. In the remaining 28 ( 64%) mothers, pSS was confirmed 1-5 years after CHB diagnosis (n=19, 68%), 6-10 years after (n= 2, 7%), or more than 10 years after the first case of CHB was diagnosed (n=7, 25%). CHB was diagnosed in uterus in all cases but two. AV block was initially incomplete in 11 fetuses and complete in 36 (no available data in 2 cases). Among the 35 (71%) surviving children with CHB, 5 (14%) developed other features of neonatal lupus. After the index pregnancy, 12 women had 20 subsequent pregnancies: five were complicated by a CHB ( recurrence rate of CHB of 25%). The 4 women who had recurrent CHB were double-positive for anti-Ro and anti-La antibodies, and all had a confirmed pSS before having the first index case of CHB. Conclusion. In pSS, autoimmune CHB could be one of the first "indirect" signs of the disease in women of childbearing-age, in whom the diagnosis is confirmed several years later. Some maternal characteristics could be related with recurrent CHB, such as having an already-confirmed diagnosis of pSS and carrying the two Ro/La autoantibodies
Autoimmune congenital heart block and primary Sjogren's syndrome:characterisation and outcomes of 49 cases
Objective. To characterise autoimmune congenital heart block (CHB) associated with a maternal diagnosis of primary Sjogren's syndrome (pSS) confirmed either before, concomitant or after the first pregnancy complicated with CHB. Methods. The following inclusion criteria were applied: (i) Mothers with positive Ro/La autoantibodies detected previously or at the time of diagnosis of the first case of CHB; (ii) diagnosis of CHB confirmed by fetal echocardiography; (iii) AV block diagnosed in uterus, at birth or within the neonatal period (0-27 days after birth) (8); (iv) absence of anatomical cardiac abnormalities which might be causal of AV block; and (v) maternal fulfillment of the 2002 SS criteria before, during or after having a pregnancy complicated with CHB. Results. We identified 49 cases of autoimmune CHB in children born from 44 mothers who had a mean age at the time of pregnancy of 30.3 years (range 18 to 41). At the time of diagnosis of autoimmune CHB, all mothers had positive anti-Ro antibodies and 28/ 44 (64%) were positive for anti-La antibodies. Only 10 (22%) mothers with affected pregnancies had a diagnosis of primary SS at the time of diagnosis of the first pregnancy complicated by CHB (a mean of 4 years before, ranging from 1 to 10 years). In 6 (14%) mothers, primary SS was diagnosed during pregnancy or less than 12 months after the delivery/termination. In the remaining 28 ( 64%) mothers, pSS was confirmed 1-5 years after CHB diagnosis (n=19, 68%), 6-10 years after (n= 2, 7%), or more than 10 years after the first case of CHB was diagnosed (n=7, 25%). CHB was diagnosed in uterus in all cases but two. AV block was initially incomplete in 11 fetuses and complete in 36 (no available data in 2 cases). Among the 35 (71%) surviving children with CHB, 5 (14%) developed other features of neonatal lupus. After the index pregnancy, 12 women had 20 subsequent pregnancies: five were complicated by a CHB ( recurrence rate of CHB of 25%). The 4 women who had recurrent CHB were double-positive for anti-Ro and anti-La antibodies, and all had a confirmed pSS before having the first index case of CHB. Conclusion. In pSS, autoimmune CHB could be one of the first "indirect" signs of the disease in women of childbearing-age, in whom the diagnosis is confirmed several years later. Some maternal characteristics could be related with recurrent CHB, such as having an already-confirmed diagnosis of pSS and carrying the two Ro/La autoantibodies
Autoimmune congenital heart block and primary Sjogren's syndrome:characterisation and outcomes of 49 cases
Monitoring of clinical signs in goats with transmissible spongiform encephalopathies
<p>Abstract</p> <p>Background</p> <p>As there is limited information about the clinical signs of BSE and scrapie in goats, studies were conducted to describe the clinical progression of scrapie and BSE in goats and to evaluate a short clinical protocol for its use in detecting scrapie-affected goats in two herds with previously confirmed scrapie cases. Clinical assessments were carried out in five goats intracerebrally infected with the BSE agent as well as five reported scrapie suspects and 346 goats subject to cull from the two herds, 24 of which were retained for further monitoring. The brain and selected lymphoid tissue were examined by postmortem tests for disease confirmation.</p> <p>Results</p> <p>The sensitivity and specificity of the short clinical protocol in detecting a scrapie case in the scrapie-affected herds was 3.9% and 99.6%, respectively, based on the presence of tremor, positive scratch test, extensive hair loss, ataxia and absent menace response. All BSE- and scrapie-affected goats displayed abnormalities in sensation (over-reactivity to external stimuli, startle responses, pruritus, absent menace response) and movement (ataxia, tremor, postural deficits) at an advanced clinical stage but the first detectable sign associated with scrapie or BSE could vary between animals. Signs of pruritus were not always present despite similar prion protein genotypes. Clinical signs of scrapie were also displayed by two scrapie cases that presented with detectable disease-associated prion protein only in lymphoid tissues.</p> <p>Conclusions</p> <p>BSE and scrapie may present as pruritic and non-pruritic forms in goats. Signs assessed for the clinical diagnosis of scrapie or BSE in goats should include postural and gait abnormalities, pruritus and visual impairment. However, many scrapie cases will be missed if detection is solely based on the display of clinical signs. PrP<sup>d </sup>accumulation in the brain appeared to be related to the severity of clinical disease but not to the display of individual neurological signs.</p
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