1,126 research outputs found
Effects of exercise modalities on arterial stiffness and wave reflection: a systematic review and meta-analysis of randomized controlled trials
Background and Objectives:
Physical activity is associated with lower cardiovascular and all-cause mortality. However, the effects of different exercise modalities on arterial stiffness are currently unclear. Our objectives were to investigate the effects of exercise modalities (aerobic, resistance or combined) on pulse wave velocity (PWV) and augmentation index (AIx), and to determine whether the effects on these indices differed according to the participants' or exercise characteristics.
Methods:
We searched the Medline, Embase and Cochrane Library databases from inception until April 2014 for randomized controlled trials lasting ≥4 weeks investigating the effects of exercise modalities on PWV and AIx in adults aged ≥18 years.
Results:
Forty-two studies (1627 participants) were included in this analysis. Aerobic exercise improved both PWV (WMD: −0.63 m/s, 95% CI: −0.90, −0.35) and AIx (WMD:−2.63%, 95% CI: −5.25 to −0.02) significantly. Aerobic exercise training showed significantly greater reduction in brachial-ankle (WMD: −1.01 m/s, 95% CI: −1.57, −0.44) than in carotid-femoral (WMD: -0.39 m/s, 95% CI: −0.52, −0.27) PWV. Higher aerobic exercise intensity was associated with larger reductions in AIx (β: −1.55%, CI −3.09, 0.0001). In addition, aerobic exercise had a significantly larger effect in reducing PWV (WMD:−1.0 m/s, 95% CI: −1.43, −0.57) in participants with stiffer arteries (PWV ≥8 m/s). Resistance exercise had no effect on PWV and AIx. There was no significant effect of combined exercise on PWV and AIx.
Conclusions:
We conclude that aerobic exercise improved arterial stiffness significantly and that the effect was enhanced with higher aerobic exercise intensity and in participants with greater arterial stiffness at baseline.
Trial Registration PROSPERO:
Database registration: CRD42014009744,
Commutation and normal ordering for operators on symmetric functions
We study the commutation relations and normal ordering between
families of operators on symmetric functions. These operators can be naturally defined by the operations of multiplication, Kronecker product, and their adjoints. As applications we give a new proof of the skew Littlewood–Richardson rule and prove an identity about the Kronecker product with a skew Schur function.Ministerio de EconomÃa y CompetitividadJunta de AndalucÃaFondo Europeo de Desarrollo Regiona
Nanohybrids of Mg/Al layered double hydroxide and long-chain (C18) unsaturated fatty acid anions: Structure and sorptive properties
10 páginas.-- 8 figuras.-- 1 tabla. 59 referencias.-- Appendix A. Supplementary data con 6 páginas (3 tablas y 2 figuras.-- Número espeical: Clay Science & Technology (XV International Clay Conference)Long-chain (C18) unsaturated fatty acid anions, elaidate (ELA), oleate (OLE), linoleate (LINO), and linolenate (LINOLEN), were intercalated into Mg/Al (3:1) layered double hydroxide (LDH) and the resultant organo-LDH nanohybrid materials were characterized and subsequently evaluated as sorbents of six pesticides (clopyralid, imazethapyr, diuron, atrazine, alachlor, and terbuthylazine). The effect of the degree (18:1, 18:2, 18:3) and
type (cis/trans) of unsaturation in the fatty acid alkyl chain on both the structure and sorptive properties of the LDH-unsaturated fatty acid nanohybrids was determined. All fatty acid anions were readily intercalated into the LDH, yielding structures with basal spacing values ranging between 32 Ã… (LDH-LINOLEN) and 40 Ã… (LDHELA).
The bend imposed by the cis geometry of the double bonds present in OLE, LINO and LINOLEN was identified as a major factor determining the arrangement of these anions in the LDH interlayer space. Intercalation of cis-unsaturated fatty acid anions led to less densely packed structures and reduced the interlayer distance of the resultant nanohybrid compared to the structures resulting from intercalation of the linear, trans-unsaturated elaidate anion. All organo-LDHs displayed higher affinity to uncharged pesticides as compared to unmodified LDH, but double bonds in the fatty acid alkyl chain, particularly when present in cis configuration, reduced the affinity of the organo-LDHs to all pesticides, presumably because they led to structures with reduced hydrophobicity as compared to those resulting from the incorporation of linear organic anions.This work has been financed by the Spanish Ministry of Economy and Competitiveness (MINECO Project AGL2011-23779) and Junta de AndalucÃa (JA Projects P07-AGR-03077 and P11-AGR-7400 and Research Group AGR-264), cofinanced with European FEDER-FSE funds (Operative Program 2007–2013). B. Gámiz thanks JA for a post-doctoral contract linked to the project P07-AGR-03077. M.A. Adelino thanks MINECO for her pre-doctoral FPI fellowship.Peer reviewe
Corrosion behaviour of titanium in the presence of Streptococcus mutans
Objective
The main aim of this in vitro study was to evaluate the influence of Streptococcus mutans on the corrosion of titanium.
Methods
S. mutans biofilms were formed on commercially pure titanium (CP-Ti) square samples (10 mm × 10 mm × 1 mm) using a culture medium enriched with sucrose. Open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements were used to evaluate the corrosion behaviour of CP-Ti in the presence of S. mutans in Fusayama's artificial saliva. The corrosion of biofilm-free CP-Ti samples was also evaluated in artificial saliva. Biofilms biomass was measured by spectrophotometry, using crystal violet staining, after 1, 2 and 7 days.
Results
The OCP values recorded on CP-Ti in the presence of S. mutans (−0.3 ± 0.02 V vs. SCE) was lower than those on biofilm-free CP-Ti (−0.1 ± 0.01 V vs. SCE) after 2 h of immersion in artificial saliva (p < 0.05). That reveals a high reactivity of titanium in presence of S. mutans. Impedance spectra revealed the formation of a compact passive film on titanium in artificial saliva or in the presence of a 2 days old S. mutans biofilm even though the corrosion resistance of CP-Ti has decreased in presence of a S. mutans biofilm.
Conclusion
The presence of bacterial colonies, such as S. mutans, negatively affected the corrosion resistance of the titanium.The authors acknowledge the financial support provided by Alban Programme (cod. E06D103407BR), the Erasmus Student Exchange Programme of the CEC, FCT (PTDC/CTM/67500/2006) and the Scientific Research Community on Surface Modification of Materials funded by the Flemish Science Foundation (WOG-FWO-Vlaanderen)
Effect of oral biofilms on the biotribocorrosion of titanium
The oral cavity is a complex environment where corrosive substances from dietary, human saliva and oral biofilms may accumulate in retentive areas of implant-supported prostheses promoting a corrosion of their surfaces. On the other side, during mastication, micro-movements may occur in artificial joints causing a relative contact motion between surfaces. Both processes result in a tribocorrosion system. The objective of this work is to investigate the in-vitro tribocorrosion behavior of titanium covered by biofilms and immersed in artificial saliva. Reciprocating sliding wear tests coupled with electrochemical techniques were performed at 25 o C on titanium samples covered or not with biofilms.
Mixed biofilms of Candida albicans and Streptococcus mutans were grown at 37 oC on titanium surfaces for 9 days in Tryptic Soy Broth medium, containing mucin, yeast extract, peptone and sucrose. The open-circuit potential (OCP) was measured until stabilization in artificial saliva. After that, electrochemical impedance spectroscopy (EIS) measurements were carried out at open circuit potential. Subsequently, sliding tests were performed at normal loads of 0.1, 0.2 and 3 N, at a sliding frequency of 1 Hz, and linear displacement amplitudes of 0.5 and 2 mm using a tribometer equipped with a test viewer software. During the sliding tests, the OCP was constantly monitored. At the end of the sliding test, the OCP was further monitored until stabilization, and another series of EIS measurements was made. Worn and unworn surfaces were inspected by SEM. The detachment of the biofilms was not noticed when low loads were applied, and biofilms appear to have some lubricating effect. However, it was found that acidic substances released from Streptococcus mutans and external substances accumulated into the biofilm might corrode surfaces located below and around the biofilms. At a normal load of 3 N, the biofilms were removed from the contact region by the sliding action, and it was observed that the repassivation rate of titanium covered with biofilms was lower than without biofilms.Fundação para a Ciência e a Tecnologia (FCT)ALBANFlemish Science Foundation. Scientific Research Community on Surface Modification of MaterialsPrograma Alban - Bolsas de Alto NÃvel da União Europeia para a América Latin
Wear and corrosion of titanium in oral simulating environments
The oral cavity can be considered as an aggressive environment to restorative materials
considering that several acidic substances can be retained in the saliva and biofilms as well as
loads from mastication and abrasive particles take place in the wear of oral surfaces. The
objective of this work is to investigate the in-vitro corrosion and wear in fluoridated artificial
saliva and in presence of biofilms. Electrochemical tests of titanium surfaces were performed in
artificial saliva containing different fluoride concentrations at 37 oC. Another group of titanium
surfaces were prepared to the growth of oral mixed biofilms for 9 days in a specific culture
medium. Then, electrochemical tests were carried out with titanium surfaces covered with
biofilms in artificial saliva without fluorides.
After that, wear sliding tests were performed in the same mediums using a tribometer equipped
with a test viewer software. Also, electrochemical measurements were carried during the wear
sliding tests. After corrosion-wear tests, worn and unworn surfaces were analyzed by AFM and
SEM. A localized corrosion of titanium was only noticed in high fluoride concentration.
Therefore, there was a decrease of the corrosion resistance of titanium when the fluoride
concentration was increased. Moreover, the presence of biofilms affected harmfully the
corrosion resistance of titanium probably due to acids release from the biofilms. However, the
wear was decreased when low loads were applied on the biofilms.Fundação para a Ciência e a Tecnologia (FCT) - PTDC/CTM/67500/2006Programa Alban - Bolsas de Alto NÃvel da União Europeia para a América Latina - E06D103407BRFlemish Science Foundation. Scientific Research Community on Surface Modification of Material
First report of a primitive neuroectodermal tumor of the bladder in a newborn
Primitive neuroectodermal tumor (PNET) is part of the Ewing sarcoma family of tumors. The present case reports a primitive neuroectodermal tumor (PNET) of rare location in the bladder in a newborn. It was evaluated with prenatal ultrasound and postnatal tomography that revealed a mass in the posterior wall of the bladder. The patient underwent partial cystectomy with subsequent analysis of the surgical piece removed, the histopathological study indicated a tumor of mesenchymal origin, and immunohistochemical staining confirmed the diagnosis of PNET of the bladder. Satisfactory result and short-term follow-up.Revisión por pare
Characterization of Interconnects Resulting from Capillary Die-to-Substrate Self-Assembly
Capillary fluidic self-assembly (SA) intrinsically features massively-parallel, contactless die handling and allows for high-precision die placement. It may thus boost die-to-substrate assembly throughput and scalability. Here we characterize for the first time indium interconnects established between dummy dies and substrates as integral part of a capillary SA process. We present a simple way to keep the solder surface free of oxide during assembly, and we show that In/Au wetting and bonding is not prevented by hydrocarbons and self-assembled monolayers locally present during processing. Resulting solder joints are characterized by mechanical shear tests, SEM and SAM. We assess the electrical functionality of interconnects with a simple test structure. Finally, we discuss the effects of an external load applied on dies during bonding. Our results open interesting perspectives for adopting capillary SA for die integration over non-planar substrates
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