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1.
Artigo em Inglês | MEDLINE | ID: mdl-38764191

RESUMO

OBJECTIVES: To compare different methods to treat hydrosalpinx, based on both ablative and non-ablative approaches, in infertile patients before undergoing IVF-ET. METHODS: Systematic review and network meta-analysis (NMA) of comparisons between different treatments of hydrosalpinx in infertile patients undergoing IVF. DATA SOURCES: structured searches in common citation databases. Study inclusion criteria: peer-reviewed randomized trials (RCT) or cohort studies comparing effects of salpingectomy, laparoscopic proximal tubal occlusion (LTO), insertion of intratubal device (ITD), sclerotherapy, ultrasound-guided aspiration and no treatment, on live birth, ongoing pregnancy, clinical pregnancy as main outcomes, considering also miscarriage, ectopic pregnancy and complications as secondary outcomes. Principal NMA included RCT, and aggregated NMA of RCT and observational studies was carried out. Pooled effects have been estimated by Odds Ratio (OR) and its 95% confidence interval (CI) for direct and indirect-mixed comparisons, derived from random-effects models. Imprecision and heterogeneity of NMA estimations was assessed by comparison of its 95% CI with predefined intervals for clinically relevant size of effect (OR <0.9 or >1.1). Surface under the cumulative ranking curve (SUCRA) were used to predict treatment rankings for each outcome. RESULTS: Nine RCT were included in main analysis, plus 17 additional observational studies in additional analysis. NMA of RCT did not identify significant differences in the effect of compared treatments on live birth rate, and LTO was the option with the highest value of SUCRA (0.92, mean rank: 1.2). Salpingectomy and US-aspiration associated to a significant increase of ongoing pregnancy rate compared to no treatment, according to NMA results (NMA OR: 4.35; 95% CI: 1.7, 11.14 and 2.8; 95% CI: 1.03, 7.58 respectively). Salpingectomy had the highest SUCRA value (0.88, mean rank: 1.4). NMA estimated significant increase of clinical pregnancy rate for salpingectomy compared with no treatment (NMA OR: 2.24; 95% CI: 1.3, 3.86) as well as for LTO versus no treatment (NMA OR: 2.55; 95% CI: 1.2, 5.41). Both comparisons were affected by a high grade of heterogeneity. For clinical pregnancy, LTO was the intervention with highest SUCRA (0.85; mean rank: 1.6). Regarding secondary outcomes, feasible NMA estimates did not support significant differences between treatments effects. According to aggregated NMA including randomized and observational studies, sclerotherapy showed significant beneficial effects on live birth rate compared to no treatment (NMA (OR: 4.6; 95% CI: 1.21, 17.46). Compared with untreated patients, the aggregated NMA estimates a higher ongoing pregnancy rate in patients treated with salpingectomy (NMA OR: 3.35; 95% CI: 2.12, 5.12), US-aspiration (NMA OR: 2.16; 95% CI: 1.28, 3.65) and LTO (NMA OR: 2.46; 95% CI: 1.11, 5.43). Salpingectomy and LTO produced a higher beneficial effect compared to ITD, based on both direct and indirect comparisons. Salpingectomy obtained the highest SUCRA value in rank of effects on ongoing pregnancy (0.94; mean rank: 1.2). NMA found significant effects on clinical pregnancy for comparisons between the different active management procedures compared with no treatments, with the exception of ITD insertion. LTO had more increasing effect on clinical pregnancy rate compared with US-aspiration (NMA OR: 2.04; 95% CI: 1.05, 3.97), while for the rest of the comparisons between procedures no significant differences were identified. NMA ranked LTO as the treatment with a highest SUCRA value (0.91; mean rank: 1.5). NMA prediction models identified LTO as best intervention to reduce miscarriage (SUCRA value: 0.84; mean rank: 1.8), as sclerotherapy as safer option in terms of ovarian response to IVF stimulation. CONCLUSIONS: The present NMA fails to support the effectiveness of any option to treat hydrosalpinx before IVF in order to improve live birth rates, although the beneficial effect of salpingectomy and US aspirations on ongoing pregnancy rates and of both salpingectomy and LTO on clinical pregnancy rates emerges from our analysis, which reinforces current recommendations. Based on the aggregated analyses, sclerotherapy could be a promising alternative to conventional laparoscopic techniques, combined with a favorable safety profile. This article is protected by copyright. All rights reserved.

2.
Tech Coloproctol ; 27(12): 1401-1403, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37815639

RESUMO

INTRODUCTION: Spondylodiscitis secondary to colposacropexy is an extremely rare entity. Infection and mesh rejection are the main causes. Removal of the mesh is essential for patient's recovery and it can be a very challenging surgical procedure. CASE: A 72-year-old woman presented with severe low back pain in the context of a recent colposacropexy. Magnetic resonance imaging was performed and spondylodiscitis secondary to prolapse correction surgery with mesh was suspected. In order to ensure an adequate recovery, removal of the mesh was required. CONCLUSIONS: Spondylodiscitis secondary to colposacropexy should be suspected when the patient starts with moderate lumbar pain and is not correctly controlled with first-level analgesia. Infection or mesh rejection should be considered. Mesh rejection should be suspected when the patient does not improve after antibiotics. Complete removal of the mesh is needed in order to ensure the patient's recovery.


Assuntos
Discite , Prolapso de Órgão Pélvico , Idoso , Feminino , Humanos , Discite/etiologia , Discite/cirurgia , Rejeição de Enxerto , Prolapso de Órgão Pélvico/cirurgia , Complicações Pós-Operatórias/etiologia , Telas Cirúrgicas/efeitos adversos
3.
J Anim Breed Genet ; 135(2): 138-148, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29363192

RESUMO

To obtain a sport horse that excels in the highest levels of competition, breeders must take into account certain genetic and environmental factors that could influence the sport horse's performance, such as the rider-horse interaction (RHI). The main aim of this study was to describe this interaction in a genetic model by modelling it in relation to the horse's age. A total of 31,129 sport results from Spanish Sport Horses were used from a total of 1,101 animals evaluated, and these were grouped in three age levels and had been ridden by 606 different riders. Only riders who had ridden more than one horse (and vice-versa) were considered for the analyses. Five linear models with different random effects were analysed according to the covariates, the homogeneity/heterogeneity of the RHI and the relevant residual random effects. The model of best fit was then selected for the genetic evaluation of the animal. In general, models including the RHI effect (M2, M4 and M5) fitted better than the other models, and the best fit was obtained for M4 (with heterogeneous residual variance). The genetic variance increased constantly with age, whereas heritability showed a response on three intervals. This study revealed the varied evolution of the RHI with age, showing the different "plastic abilities" of this relationship.


Assuntos
Cavalos/genética , Cavalos/fisiologia , Modelos Genéticos , Resistência Física , Animais , Desempenho Atlético , Feminino , Variação Genética , Cavalos/classificação , Humanos , Masculino
4.
Facts Views Vis Obgyn ; 16(1): 9-22, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38551471

RESUMO

Background: Congenital uterine anomalies (CUA) can be associated with impairments of early and late pregnancy events. Objective: To assess the impact of CUA on reproductive outcomes in pregnancies conceived spontaneously or after assisted reproduction. Materials and Methods: Systematic review and meta-analysis of cohort studies comparing patients with CUA versus women with normal uterus. A structured literature search was performed in leading scientific databases to identify prospective and retrospective studies. The Newcastle-Ottawa scale, adapted to AHRQ standards, was used to assess the risk of bias. Pooled odds ratios (OR) were calculated. Publication bias and statistical heterogeneity were assessed, and meta-regression was used to analyse the heterogeneity. Main outcome measures: Miscarriage, ectopic pregnancy, placental abruption, term, and premature rupture of membranes (PROM), malpresentation at delivery, preterm delivery prior to 37, 34 and 32 weeks, caesarean delivery, intrauterine growth restriction/small for gestational age, foetal mortality and perinatal mortality. Results: 32 studies were included. CUAs increased significantly the risk of first/second trimester miscarriage (OR:1.54;95%CI:1.14-2.07), placental abruption (OR:5.04;3.60-7.04), PROM (OR:1.71;1.34-2.18), foetal malpresentation at delivery (OR:21.04;10.95-40.44), preterm birth (adjusted OR:4.34;3.59-5.21), a caesarean delivery (adjusted OR:7.69;4.17-14.29), intrauterine growth restriction/small for gestational age (adjusted OR:50;6.11-424), foetal mortality (OR:2.07;1.56-2.73) and perinatal mortality (OR:3.28;2.01-5.36). Conclusions: CUA increases the risk of complications during pregnancy, delivery, and postpartum. Complications most frequent in CUA patients were preterm delivery, foetal malpresentation, and caesarean delivery. What is new?: Bicornuate uterus was associated with the highest number of adverse outcomes, followed by didelphys, subseptate and septate uterus.

5.
J Anim Breed Genet ; 130(3): 190-8, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23679944

RESUMO

The purpose of this study was to study phenotypic plasticity ability for Show Jumping performance in horses according to age differences. For this study, 11 352 participations, belonging to 1085 horses grouped by age (4-, 5- or 6-year olds), were analysed. repeatability animal models (RAM) and multiple trait animal models (MTAM) were compared. RAM assumed the same covariance components for all age groups, whereas MTAM considered the results of every animal at every age group as different (but correlated) traits. The age, sex, starting order and training level were included as fixed effects. The random effects were the animal, the individual permanent environment, the competition and the rider. Six models were compared, and the rider-horse interaction was added as a random effect; furthermore, heterogeneous residual variance was taken into consideration only for MTAM. The study of the genetic correlations between age groups highlighted the presence of an age-genotype interaction and, therefore, an underlying environmental effect. This study may allow us to select horses with a plastic response, which show either a gradual response or a precocious response and thus gain or lose genetic potential with age, respectively.


Assuntos
Cavalos/genética , Cavalos/fisiologia , Fenótipo , Esportes , Fatores Etários , Análise de Variância , Animais , Cruzamento , Feminino , Masculino , Modelos Teóricos , Destreza Motora/fisiologia , Espanha
6.
Dalton Trans ; 52(21): 7258-7270, 2023 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-37166156

RESUMO

We present the synthesis, through a simple, microwave-assisted method, of lanthanoid-based 2D metal-organic frameworks (MOFs) of general formula [LnxLn'1-x(MeCOO)(PhCOO)2], including homonuclear compounds (x = 1), LnEu, Tb, and heterometallic compounds, [TbEu]. The crystalline material is formed by neutral nanosheets held together by van der Waals interactions, which can be easily exfoliated by sonication. Photoluminescent emission in the visible range was observed for all of the synthesized 2D MOF compounds via excitation of the ligand, showing benzoates are efficient antenna ligands. Efficient energy transfer from Tb → Eu was observed in the heterometallic [TbEu] compounds, which could potentially perform as luminescent thermometers. Inks containing nanosheets of 2D MOFs exfoliated in solution were prepared, and luminescent prints of Tb and Eu 2D MOFs on paper were made to show the possible application for anticounterfeiting. Frequency-dependent ac susceptibility results show the occurrence of slow magnetic relaxation in [TbEu] compounds through direct relaxation mechanisms, affected by bottleneck effect. A slowing down of the relaxation time is observed as the Eu/Tb ratio increases.

9.
Dalton Trans ; 49(39): 13671-13684, 2020 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-32996514

RESUMO

Coumarin-based lanthanide complexes of general formula [Ln(coum)3(phen)(H2O)x]·yH2O (Ln-phen, x = 0,1, 0 ≤ y ≤ 1.5; phen = 1,10-phenanthroline; coum = 3-acetyl-4-hydroxylato-coumarin; Ln = Eu, Tb, Dy, Tm) and [Ln(coum)3(batho)]·0.7EtOH (Ln-batho, batho = 4,7-diphenyl-1,10-phenanthroline; Ln = Eu, Tb, Dy, Tm) were synthesized. The magnetic relaxation and photoluminescence behavior of these complexes was compared with that of the related compounds [Ln(coum)3(EtOH)(H2O)]·EtOH (Ln-coum), so as to investigate the effects of incorporating a second chromophore, either the phen or batho ligand, to the original coordination scaffold, provided with three coumarin (coum) ligands. Slow relaxation of the magnetization under H = 0 with moderate activation energies was observed for the Dy-phen (U/kB = 99.1 K) and Dy-batho (U/kB = 67.1 K) compounds, whereas Tb analogues presented field-induced single molecule magnet (SMM) behavior, with U/kB = 11.7 K (16.6 K@3 kOe) for Tb-phen (Tb-batho), respectively. Luminescent emission in the visible range was observed for all the Ln-coumarin based compounds upon ligand sensitization, with high quantum yields of 45 (40%) for Eu-phen (Eu-batho) compounds and 65-76-58% for Tb-coum, phen, batho analogues. Sensitization is mainly provided by the coumarin ligand having the energy difference ΔE between its triplet state T1 and the lanthanide emitting level closest to the optimum, while the second ligand can play either a synergistic or competing sensitizing role. The Tb-phen/batho compounds presented simultaneously SMM and luminescent behavior, with excellent values of the bifunctional figure of merit (ηSMM-QY ∼ 1000% K). The reported compounds represent a new class of bifunctional materials with potential interesting application in various fields.

10.
Animal ; 14(7): 1351-1361, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32026801

RESUMO

Reproductive traits have a major influence on the economic effectiveness of horse breeding. However, there is little information available. We evaluated the use of reproductive traits as selection criteria in official breeding programs to increase the reproductive efficiency of breeding studs, analysing 696 690 records from the pedigree data of eight Spanish horse populations, with different breeding purposes. The reproductive parameters studied in both sexes were age at first foaling (AFF), age at last foaling, average reproductive life and generational interval. In the females, the average interval between foaling (AIF) and interval between first and second foaling were also studied. There were clear differences between sexes and breeds, which may be due to management practices, breeding purposes and the status of the populations, rather than to differences in actual physiological conditions. Riding mares were the most precocious (AFF, 1937.64 to 2255.69 days) and had a more intensive reproductive use (AIF, 625.83 to 760.07 days), whereas sires used for meat production were the most precocious males (AFF, 1789.93 to 1999.75 days), although they had a shorter reproductive life (1564.34 to 1797.32 days). Heritabilities (0.02 to 0.42 in females and 0.04 to 0.28 in males) evidenced the genetic component of the reproductive traits, with Sport Horses having the higher average values. These results support the selection by AFF to improve reproductive aspects because of its medium-high heritability and its positive correlations with other important reproductive traits. The inclusion of the AIF is also recommended in sport populations, because this determines the length of the breaks between foaling and conditions the reproductive performance of the dams, as well as their selective intensity, genetic gain and genetic improvement. It is therefore an important economic parameter in breeding studs.


Assuntos
Cruzamento , Cavalos , Reprodução , Animais , Feminino , Cavalos/genética , Masculino , Carne , Linhagem , Fenótipo , Reprodução/genética
11.
Dalton Trans ; 48(15): 5022-5034, 2019 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-30916067

RESUMO

We report the synthesis, crystal structure and magnetic properties of a new heteronuclear polymeric complex based on non-Kramers Tb ions and carboxylic α-fur = C4H3OCOO ligands: {[Tb2Ba(α-fur)8(H2O)4]·2H2O}n. The α-furoate ligands consolidate 1D zig-zag chains running along the c-axis, formed by Tb2 dimers separated by Ba ions. Ab initio calculations, in combination with the fit of experimental data, predict that the single-ion magnetic ground state is highly anisotropic () and consists of a quasi-doublet with a ΔTb/kB = 3.22 K gap, well separated from the next excited state, while the gap for the Tb2 dimer is Δ2Tb/kB = 2.58 K. Static magnetization and heat capacity measurements show that, magnetically, the system can be modeled as dimers of non-Kramers Tb ions, coupled by an antiferromagnetic intradimer interaction J'*/kB = -1.6 K. Dipolar interactions couple the Tb ions in the dimer with their first neighbour ions along the chain, with J''*/kB = -0.15 K, and with the surrounding ions out of the chain, with maximum J'''*/kB = -0.03 K. Ac susceptibility measurements in H = 0 performed down to 50 mK temperatures have enabled us to observe slow relaxation of magnetization, with an Orbach-like activation energy of U/kB = 1.1 K. It is assigned to the sluggish response of the 3D spin system due to a short-range ordering, possibly enhanced by the presence of disorder caused by defects in the polymeric chains. Under the application of a magnetic field, the system slowly relaxes by two distinct direct processes, strongly affected by a phonon bottleneck effect. We discuss the different relaxational phenomenology of the new complex in comparison with that of the isostructural {[Dy2Ba(α-fur)8(H2O)4]·2H2O}n, differing only in the Kramers nature of the ions, and the mononuclear {Ln(α-fur)3(H2O)3}n (Ln = Tb, Dy) complexes, previously reported.

12.
Dalton Trans ; 48(41): 15386-15396, 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31257389

RESUMO

Two new neodymium molecular magnets of formula {[Nd(α-fur)3(H2O)2]·DMF}n (1) and {[Nd0.065La0.935(α-fur)3(H2O)2]}n (2), α-fur = C4H3OCOO, have been synthesized. In (1) the furoate ligands, in bidentate bridging mode, consolidate zig-zag chains running along the a-direction. Compound (2) is a magnetically diluted complex of a polymeric chain along the b-axis. Heat capacity, dc magnetization and ac susceptibility measurements have been performed from 1.8 K up to room temperature. Ab initio calculations yielded the gyromagnetic factors gx* = 0.52, gy* = 1.03, gz* = 4.41 for (1) and gx* = 1.35, gy* = 1.98, gz* = 3.88 for (2), and predicted energy gaps of Δ/kB = 125.5 K (1) and Δ/kB = 58.8 K (2). Heat capacity and magnetometry measurements agree with these predictions, and confirm the non-negligible transversal anisotropy of the Kramers doublet ground state. A weak intrachain antiferromagnetic interaction J'/kB = -3.15 × 10-3 K was found for (1). No slow relaxation is observed at H = 0, attributed to the sizable transverse anisotropy component, and/or dipolar or exchange interactions enhancing the quantum tunnelling probability. Under an external applied field as small as 80 Oe, two slow relaxation processes appear: above 3 K the first relaxation mechanism is associated to a combination of Orbach process, with a sizeable activation energy U/kB = 121 K at 1.2 kOe for (1), Raman and direct processes; the second, slowest relaxation mechanism is associated to a direct process, affected by phonon-bottleneck effect. For complex (2) a smaller U/kB = 61 K at 1.2 kOe is found, together with larger g*-transversal terms, and the low-frequency process is quenched. The reported complexes represent rare polymeric Nd single-ion magnets exhibiting high activation energies among the scarce Nd(iii) family.

13.
Dalton Trans ; 44(31): 14178, 2015 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-26193067

RESUMO

Correction for 'Magnetic relaxation versus 3D long-range ordering in {Dy2Ba(α-fur)8}n furoate polymers' by E. Bartolomé et al., Dalton Trans., 2014, 43, 10999-11013.

14.
Clin Chim Acta ; 301(1-2): 87-102, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11020465

RESUMO

As oxidative stress in relation with neurological diseases has become an important point in recent research, simple methods to be used in epidemiological studies and clinical practice are required. The hypothesis that the analytical methods used in research laboratories (RLM) can be used interchangeably with commercial kits (CKM) for SOD and TRAP is tested. Both methods were compared using linear transformations of the RLM measurements into the CKM scales. Data were obtained from Alzheimer's, Parkinson's, and vascular dementia patients and controls. The lack of fit and the run's test of residuals were not significant, but the same sign method detected significant nonlinearities (P<0.000001 for SOD, P<0.01 for TRAP). The intragroup CVs of both methods were comparable for TRAP, while in the RLM determinations of SOD resulted in <50% of those obtained with the CKM. The ANCOVA comparison of the regression parameters across the clinical groups resulted significant for SOD (P<0.0001) and not significant for TRAP. Both methods agree in describing the features of the clinical groups, but the degree of agreement at the individual concentration was poor and they could not be readily intercalibrated. Normal and pathological values should be obtained independently for the CKM to insure their applicability to large populations.


Assuntos
Doença de Alzheimer/sangue , Antioxidantes/metabolismo , Demência Vascular/sangue , Doença de Parkinson/sangue , Superóxido Dismutase/sangue , Doença de Alzheimer/enzimologia , Estudos de Casos e Controles , Demência Vascular/enzimologia , Humanos , Doença de Parkinson/enzimologia
15.
Rev Neurol ; 31(1): 1-8, 2000.
Artigo em Espanhol | MEDLINE | ID: mdl-10948573

RESUMO

INTRODUCTION AND OBJECTIVE: Pyramidal gait impairment (GI) is a classical trait of cerebrovascular disease (CVD). To developed a method to quantify prospectively and transversely GI and disequilibrium, to be applied in the screening of pyramidal and non-pyramidal syndromes associated to different ethiological subtypes of CVD; using an Index of Gait and Equilibrium (IGE). PATIENTS AND METHODS: In constructing IGE, we used 14 equally weighted semiological variables: 6 measure balance, 6 gait, 1 sensitive abnormalities and 1 falls. Two neurologists separately examined each subject in the same day and repeating the evaluation after a week. Data analyses included Kruskal Wallis, chi 2, Spearman correlations and Principal Components. RESULTS: IGE was used in 90 subjects, 43 males, with a mean age of 70.6 years. 3 groups of people were formed: 1. CVD (A, 21 with silent vascular lesions diagnosed by imaging; B, 17 with vascular dementia; C, 21 with stroke); 2. 13 subjects with cautious gait, not associated to any disease; and 3. 18 normal control subjects (age 60-80 years). GI in the non-pyramidal syndrome were significantly related with small vessels disease (chi 2 = 16.37, dof = 1, p < 0.001). CONCLUSIONS: GI in CVD, pyramidal and non-pyramidal syndromes were equally frequent. Increased values of IGE caused by cautious gait in youngest non-stroke patients suggested high probability of silent CVD and significant association with small vessels disease. This preliminary assessment of IGE showed a reproducible and reliable tool for objectification and quantification of gait disorders.


Assuntos
Infarto Cerebral/complicações , Marcha , Transtornos dos Movimentos/etiologia , Idoso , Idoso de 80 Anos ou mais , Encéfalo/irrigação sanguínea , Encéfalo/patologia , Infarto Cerebral/diagnóstico , Estudos Transversais , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Transtornos dos Movimentos/diagnóstico , Exame Neurológico , Equilíbrio Postural , Estudos Prospectivos , Índice de Gravidade de Doença
17.
Dalton Trans ; 43(32): 12342-56, 2014 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-24988294

RESUMO

The lanthanide(iii) cyanoacetate complexes of the formula {[Ln2(CNCH2COO)6(H2O)4]·2H2O}n, where Ln = Eu (), Gd (), Nd (), have been prepared and characterized by X-ray diffraction analysis. Complexes and are isostructural and differ from the binding scheme of the neodymium compound , structurally described earlier. In all cases, the cyano group of the cyanoacetate ligand is not coordinated to the lanthanide cation. The carboxylic groups exhibit different binding modes: 2-bidentate-chelating, 2-bidentate and 2-tridentate-chelating bridging for and , and 4-bidentate and 2-tridentate-chelating bridging for the complex . The Eu compound shows field induced paramagnetism, as expected for a non-magnetic ground state with mixing from higher states. Combining the dc magnetization and luminescence measurements the spin-orbit coupling constant λ = 343 ± 4 cm(-1) was found, averaged over the two different sites for Eu in the lattice. In the Gd complex , a crystal field splitting of D/kB = -0.11 ± 0.01 K has been found for the S = 7/2 multiplet of the Gd(iii) ion. No slow relaxation at H = 0 is observed because the low anisotropy barrier allows fast spin reversal through classical processes. The application of an external magnetic field induces two slow relaxation processes. It is argued that the first relaxation rate is caused by the resonant phonon trapping (RPT) mechanism, while the second, slower relaxation rate is due to the lifting of the Kramers degeneracy on the ground state. For compound heat capacity and dc susceptibility measurements indicate that at very low temperatures the ground state Kramers doublet has strong single ion anisotropy. The energy to the next excited doublet ΔZFS/kB = 104 K has been calculated by ab initio calculation methods. The g* tensor has also been calculated, showing that it has predominant anisotropy along the z-axis, and there is an important transversal component. At H = 0 quantum tunnelling is an effective mechanism in producing a fast relaxation to equilibrium at temperatures above 1.8 K. The dipolar or exchange interactions and a sizable transverse anisotropy component in the ground state enhance the quantum tunneling probability. Under an external applied field, two slow relaxation processes appear: above 3 K the first relaxation mechanism is of the Orbach type, with an activation energy U/kB = 27 K; the slower relaxation is caused by the direct relaxation process from the ground state to the Kramers split levels by the applied field.

18.
Dalton Trans ; 43(28): 10999-1013, 2014 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-24911469

RESUMO

A novel Dy-complex formulated as {[Dy2Ba(α-C4H3OCOO)8·(H2O)4]·2H2O}n, {Dy2Ba(α-fur)8}n, has been synthesized, structurally characterized, and magnetically and thermally investigated as a function of field and temperature, down to 85 mK. The α-furoate ligands consolidate 1D zig-zag chains formed by Dy2 dimers separated by Ba ions. Ab initio calculations were used to determine the easy anisotropy axis direction, the gyromagnetic tensor components and the energy levels of each Dy. The heat capacity and susceptibility measurements allowed us to conclude that intradimer and interdimer interactions are ferromagnetic and of the same order, J'/k(B) ≈ J''/k(B) = +0.55 K. In the absence of an applied magnetic field, the dynamic relaxation of the magnetization occurs through the fast (τ(T) ~ 10(-5) s) spin-reversal of each of the individual Dys through a quantum tunneling (QT) process. A long-range 3D ordered state is achieved at T(N) = 0.25 K, in which the ferromagnetically coupled zig-zag chains (J'/k(B) ≈ J''/k(B) = +0.528(1) K) running along the c-axis are antiferromagnetically coupled to the adjacent chains (J'''/k(B) = -0.021(1) K). Critical slowing down of the QT time constant is observed when the temperature approaches T(N). Under the application of a magnetic field, the QT relaxation is replaced by an Orbach process (with energy barrier U/k(B) = 68 K and τ0 ~ 10(-9) s at H = 2 kOe) and a very slow (τ(s) ∼ 0.2 s) relaxation process. We propose and demonstrate the proof of concept of a spintronic device, in which two different relaxation rates can be selected, and on/off switched by magnetic field biasing. The dynamical behavior of this compound is compared with another furoate to discuss the effect of competitive interactions.

19.
Dalton Trans ; 43(35): 13349-57, 2014 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-25078125

RESUMO

The room temperature reaction of [Mn2O2(bipy)4](ClO4)3 (bipy = 2,2'-bipyridine) with Ca(CHCl2COO)2 in methanol produced a yellow crystalline material. The X-ray determined structure comprises of a multiple calcium(II) carboxylate bridged chain-like structure which is decorated with [Mn(bipy)2(OH2)](2+) subunits. The redox behaviour for the complex in H2O and MeCN is reported. In the latter solvent the oxidation of the manganese ions appears to be facilitated by the presence of the calcium ions. Magnetic susceptibility and low temperature magnetization measurements show that the Mn moment is isotropic, with g = 1.99(1) and S = 5/2, confirming it is in the 2+ oxidation state. A very weak antiferromagnetic interaction is also detected. Frequency-dependent ac measurements evidence slow magnetic relaxation of the Mn(bipy)2 units. Two relaxation mechanisms are identified: a very slow direct process and a faster one caused by the Resonant Phonon Trapping mechanism. This is the first example of field-induced single ion magnet (SIM) behavior in a mononuclear Mn(II) complex.


Assuntos
Cálcio/análise , Cálcio/química , Manganês/análise , Manganês/química , Cristalografia por Raios X , Estrutura Molecular , Espectrofotometria Ultravioleta/métodos
20.
Clín. investig. ginecol. obstet. (Ed. impr.) ; Clín. investig. ginecol. obstet. (Ed. impr.);50(3): [100853], Jul-Sep. 2023. tab, ilus
Artigo em Espanhol | IBECS (Espanha) | ID: ibc-223316

RESUMO

Dentro de la patología intracavitaria estructural, los miomas submucosos plantean una mayor dificultad de manejo frente a los pólipos. Dentro de los miomas submucosos los miomas tipo0 y1 son más fáciles de tratar, dado que su separación del miometrio subyacente es técnicamente más fácil. Así, las cirugías histeroscópicas más complicadas son actualmente las miomectomías de miomas submucosos tipo2.Se ha empezado a describir también el manejo histeroscópico de miomas tipo3 por histeroscopia.Con este artículo planteamos hacer una revisión de los puntos más relevantes para llevar a cabo un tratamiento adecuado de este tipo de miomas, revisando su diagnóstico, las técnicas quirúrgicas, la preparación de la paciente y la forma de evitar complicaciones quirúrgicas.(AU)


Within structural intracavitary pathology, submucosal myomas are more difficult to manage than polyps. Of the submucosal myomas, type0 and type1 are easier to treat because their separation from the underlying myometrium is technically easier. Therefore, the most complicated hysteroscopic surgeries are currently type2 submucosal myomectomies.We have also begun to describe the hysteroscopic management of type3 myomas.With this article we propose to make a review of the most relevant points for the correct treatment of this type of myoma, reviewing its diagnosis, surgical techniques, patient preparation, and how to avoid surgical complications.(AU)


Assuntos
Humanos , Feminino , Mioma , Histeroscopia/instrumentação , Histeroscopia/métodos , Histeroscopia/tendências , Lasers , Vasopressinas , Doenças Uterinas , Ginecologia
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