High thermal conductivity, structural stability, good mechanical and anti-oxidant properties makes hexagonal boron nitride (h-BN) a promising functional filler for polymers to produce composite ...materials where excellent thermal management is required, such as in electronic devices. Theoretical studies have revealed that two dimensional (2D) BN has higher thermal conductivity (up to 400 Wm−1 K−1, in-plane) than bulk h-BN due to a reduction in phonon-phonon scattering when scaling down the thickness of the material. For this reason, 2D boron nitride nanosheets (BNNS) are gaining intense interest since they could be utilised in the design of composite materials with excellent efficiency to dissipate heat. Various methods have been explored to produce 2D BNNS including mechanical and chemical exfoliation of pristine bulk BN, chemical reaction, chemical vapour deposition (CVD) and electron irradiation. To facilitate the dispersion of BNNS in polymers, different functionalization strategies have been applied for surface-treatment of BNNS. In this review, the different synthesis approaches adopted for BNNS are compared and the effects of BNNS dispersion on the thermal conduction of polymers are discussed. The factors influencing the mechanism of thermal conduction such as materials crystallinity, filler geometry, filler surface functionalization and alignment, filler/matrix interface and processing conditions are discussed. Some perspectives and future directions on how to generate high thermally conductive composites of BNNS and polymer are proposed.
Age and gender specific prevalence rates for parkinsonism and Parkinson's disease (PD) are important to guide research, clinical practice, and public health planning; however, prevalence estimates in ...Latin America (LatAm) are limited. We aimed to estimate the prevalence of parkinsonism and PD and examine related risk factors in a cohort of elderly individuals from Latin America (LatAm).
Data from 11,613 adults (65+ years) who participated in a baseline assessment of the 10/66 study and lived in six LatAm countries were analyzed to estimate parkinsonism and PD prevalence. Crude and age-adjusted prevalence were determined by sex and country. Diagnosis of PD was established using the UK Parkinson's Disease Society Brain Bank's clinical criteria.
In this cohort, the prevalence of parkinsonism was 8.0% (95% CI 7.6%–8.5%), and the prevalence of PD was 2.0% (95% CI 1.7%–2.3%). PD prevalence increased with age from 1.0 to 3.5 (65–69vs. 80 years or older, p < 0.001). Age-adjusted prevalence rates were lower for women than for men. No significant differences were found across countries, except for lower prevalence in urban areas of Peru. PD was positively associated with depression (adjusted prevalence ratio aPR 2.06, 95% CI 1.40–3.01, I2 = 56.0%), dementia (aPR 1.57, 95% CI 1.07- 2.32, I2 = 0.0%) and educational level (aPR 1.14, 95% CI 1.01– 1.29, I2 = 58.6%).
The reported prevalence of PD in LatAm is similar to reports from high-income countries (HIC). A significant proportion of cases with PD did not have a previous diagnosis, nor did they seek any medical or neurological attention. These findings underscore the need to improve public health programs for populations currently undergoing rapid demographic aging and epidemiological transition.
The funding source had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
The folding of RNA and DNA strands plays crucial roles in biological systems and bionanotechnology. However, studying these processes with high-resolution numerical models is beyond current ...computational capabilities due to the timescales and system sizes involved. In this article, we present a new coarse-grained model for investigating the folding dynamics of nucleic acids. Our model represents three nucleotides with a patchy particle and is parameterized using well-established nearest-neighbor models. Thanks to the reduction of degrees of freedom and to a bond-swapping mechanism, our model allows for simulations at timescales and length scales that are currently inaccessible to more detailed models. To validate the performance of our model, we conducted extensive simulations of various systems: We examined the thermodynamics of DNA hairpins, capturing their stability and structural transitions, the folding of an MMTV pseudoknot, which is a complex RNA structure involved in viral replication, and also explored the folding of an RNA tile containing a k-type pseudoknot. Finally, we evaluated the performance of the new model in reproducing the melting temperatures of oligomers and the dependence on the toehold length of the displacement rate in toehold-mediated displacement processes, a key reaction used in molecular computing. All in all, the successful reproduction of experimental data and favorable comparisons with existing coarse-grained models validate the effectiveness of the new model.
2,4:3,5-Di-O-methylene-d-mannitol, abbreviated as Manx, is a d-mannitol-derived compound with the secondary hydroxyl groups acetalized with formaldehyde. The bicyclic structure of Manx consists of ...two fused 1,3-dioxane rings, with two primary hydroxyl groups standing free for reaction. A homopolyester made of Manx and dimethyl terephthalate as well as a set of copolyesters of poly(butylene terephthalate) (PBT) in which 1,4-butanediol was replaced by Manx up to 50% were synthesized and characterized. The polyesters had M w in the 30 000–52 000 g mol–1 range and a random microstructure and were thermally stable up to nearly 370 °C. They displayed outstanding high T g with values from 55 to 137 °C which steadily increased with the content in Manx. Copolyesters containing up to 40% of Manx were semicrystalline and adopted the crystal structure of PBT. Their stress–strain parameters were sensitively affected by the presence of carbohydrate-based units with elongation at break decreasing but tensile strength and elastic moduli steadily increasing with the degree of replacement.
Abstract
A growing body of research suggests a positive association between the quality of export products and income per capita, arguing that quality upgrades affect income through changes in the ...relative demand for skilled labor. This article falls within this literature and intends to shed light on the effect of quality upgrades of export products on average wages at the industry level. The study is conducted on the manufacturing sector over a set of 23 countries for which industry-level wage data are available. Contrary to previous studies which use unit values as an indirect measure of product quality, we rely on the methodology proposed in Khandelwal (Rev Econ Stud 77(4):1450–1476. https://doi.org/10.1111/j.1467-937X.2010.00602.x, 2010) and estimate quality as a residual of a demand equation. To establish a direct causal link between export quality upgrades and changes in wages, we use an instrumental variable strategy. Our results show that ahead of upgrades to export quality within a specific industry, average wages offered within the industry increase. In addition, we observe that the effect is larger for developing countries. Our findings imply that export product quality upgrades require more intensive use of qualified workers, who require higher wages.
Mature fetiform teratoma, or homunculus, is a term coined for a rare variant of teratoma with a prevalence of 0.01% of teratomas. There have been very few cases reported in the world, and its ...thoracic presentation is extremely unusual. We present the case of a 31-year-old female patient with a history of progressive chest pain in the left hemithorax, associated with dyspnea on moderate exertion and cough. Imaging studies revealed a large intrathoracic tumor visually compatible with a teratoma. Surgical resection by a clamshell approach was successful, and subsequent anatomopathological studies of the operative specimen concluded that the mass was a mature fetiform thoracic teratoma. The treatment of this entity is generally surgical and includes wide resection due to its large adhesive component to surrounding tissues. Thus, the cardiothoracic surgeon must know approaches that allow wide resection, making these cases true surgical challenges.
Ovotesticular disorders of sex development (OT-DSD) are characterized by ovarian follicles and seminiferous tubules in the same individual, with a wide range of atypical genitalia. We report on two ...sibs with atypical genitalia and SRY-negative 46,XX DSD, OT-DSD was confirmed only in the boy, while the girl had bilateral ovaries. Chromosome microarray analysis (CMA) showed a 737-kb duplication at Xq27.1 including the entire SOX3 gene in both sibs, which was confirmed by quantitative real time PCR. Also, X chromosome inactivation assay showed random inactivation in both sibs. Whole exome sequencing revealed no pathogenic or likely pathogenic variant. CMA of the parents showed normal results for both, suggesting that germline mosaicism could be the reason of recurrence of this duplication in the siblings. Our results support a pathogenic role of SOX3 overexpression in 46,XX subjects leading to variable DSD phenotypes.
Pericytes in the Premetastatic Niche Paiva, Ana E; Lousado, Luiza; Guerra, Daniel A P ...
Cancer research (Chicago, Ill.),
06/2018, Letnik:
78, Številka:
11
Journal Article
Recenzirano
Odprti dostop
The premetastatic niche formed by primary tumor-derived molecules contributes to fixation of cancer metastasis. The design of efficient therapies is limited by the current lack of knowledge about the ...details of cellular and molecular mechanisms involved in the premetastatic niche formation. Recently, the role of pericytes in the premetastatic niche formation and lung metastatic tropism was explored by using state-of-the-art techniques, including
lineage-tracing and mice with pericyte-specific KLF4 deletion. Strikingly, genetic inactivation of KLF4 in pericytes inhibits pulmonary pericyte expansion and decreases metastasis in the lung. Here, we summarize and evaluate recent advances in the understanding of pericyte contribution to premetastatic niche formation.
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