Effects of chemical modification and nanotechnology on wood properties

As a green material, wood is widely used in building decoration, railway construction, and other fields. However, the wood itself has inherent defects of being easy to absorb water and deform, rot, and decrease in strength. The physical and mechanical strengths and stability of artificial fast-growing forest wood are even worse. As wood modification can improve the dimensional stability, durability, strength, and other properties of wood, it has been widely used. Chemical modification is the main method of wood modification. The development of nanotechnology has brought more possibilities for wood modification. Owing to the extensive literature available, this article summarizes the representative achievements of wood chemical modification and nanotechnology. The principle, production process, advantages, and disadvantages of various wood chemical modification methods were analyzed, compared, and evaluated. Finally, according to the application status of wood-modified materials, the problems existing in the current wood chemical modification methods and the application of nanotechnology, and the development trend in the future are analyzed

Review of connections for engineered bamboo structures

Bamboo is a green building material that is environmentally friendly and has great development value. However, the limited mechanical properties and heterogeneous dimensions of natural bamboo poles curb the application of bamboo in building structures. A transverse section of engineered bamboo is regular and compact, and its mechanical properties are stable, which can meet the requirements for physical and mechanical properties of materials in modern building structures. Though application of engineered bamboo has just started, it is of great significance to study the connection performance and corresponding influence factors for popularization and application of modern bamboo structures. This paper is focused on a review of research progress for connections in engineered bamboo structures. Firstly, a study on embedding strength and the performance of bolted joints is presented, including calculation methods described with a proposal for future development of standards suitable for the characteristics of engineered bamboo materials. Secondly, research on carpentry joints is introduced, namely tenon-mortise joints, nail joints and truss plate joints. Finally, some engineering examples are briefly introduced. This work can provide a reference for further research on connections in engineered bamboo structures

Sex/Gender- and Age-Related Differences in β-Adrenergic Receptor Signaling in Cardiovascular Diseases

Sex differences in cardiovascular disease (CVD) are often recognized from experimental and clinical studies examining the prevalence, manifestations, and response to therapies. Compared to age-matched men, women tend to have reduced CV risk and a better prognosis in the premenopausal period. However, with menopause, this risk increases exponentially, surpassing that of men. Although several mechanisms have been provided, including sex hormones, an emerging role in these sex differences has been suggested for β-adrenergic receptor (β-AR) signaling. Importantly, β-ARs are the most important G protein-coupled receptors (GPCRs), expressed in almost all the cell types of the CV system, and involved in physiological and pathophysiological processes. Consistent with their role, for decades, βARs have been considered the first targets for rational drug design to fight CVDs. Of note, β-ARs are seemingly associated with different CV outcomes in females compared with males. In addition, even if there is a critical inverse correlation between β-AR responsiveness and aging, it has been reported that gender is crucially involved in this age-related effect. This review will discuss how β-ARs impact the CV risk and response to anti-CVD therapies, also concerning sex and age. Further, we will explore how estrogens impact β-AR signaling in women

Review on Connections for Original Bamboo Structures

Bamboo is a green construction material in line with sustainable development strategies. The use of raw bamboo in architecture has existed since ancient times. In the long development years of original bamboo buildings, many areas in the world gradually formed unique bamboo buildings, which have become an important local cultural feature. For building structures, joints are the key to ensure structural load transfer. Because of hollow and thin-walled material property of bamboo, the connection in raw bamboo buildings has always been a major difficulty and problem in the application of bamboo, which seriously hinders the development of original bamboo structures. In order to promote the use of raw bamboo, two traditional connection methods in raw bamboo structures are described in this paper firstly, with the advantages and disadvantages of the two methods pointed out. Also, research progress on four categories of raw bamboo building joints is described namely, bolt joints, steel member joints, filler reinforced joints and other types of joints. This work can provide a reference for future research and engineering applications

Slenderness Ratio Effect on the Eccentric Compression Performance of Chamfered Laminated Bamboo Lumber Columns

Eccentric compression tests on 15 chamfered laminated bamboo lumber (LBL) columns with a height ranging from 600 to 3000 mm were conducted in order to study the eccentric mechanical performance. The failure of all specimens was caused by the crack of bamboo fiber in the tensile region. When the ultimate strength was reached, except specimens with a height of 600 mm, all other specimens could bear large deformation, showing good ductility. The lateral displacements of the specimens under eccentric compression were approximately parabolic in the direction of column height. The ultimate bending moment of LBL columns with different slenderness ratios under compression with the same initial eccentricity was a fixed value. The relationship between ultimate capacity, axial displacement, lateral displacement, and slenderness ratio was analyzed based on test results. It was found that the plane section assumption could be used to express the stress and strain distribution of chamfered LBL columns under eccentric compression. A method for calculating the ultimate bearing capacity was proposed using a constitutive model based on the Ramberg-Osgood relation and the empirical formula for calculating the ultimate capacity was given on the basis of the former research as well as the test results in this paper

Properties and Applications of Bamboo Fiber-A Current-State-of-the Art

Fibers are used in many forms in engineering applications–one of the most common being used as reinforcement. Due to its renewable short natural growth cycle and abundance of bamboo resources, bamboo fiber has attracted attention over other natural fibers. Bamboo fiber has a complex natural structure but offers excellent mechanical properties, which are utilized in the textile, papermaking, construction, and composites industry. However, bamboo fibers can easily absorb moisture and are prone to corrosion limiting their use in engineering applications. Therefore, a better understanding of bamboo fiber is particularly important. This paper reviews all existing research on the mechanical characterization of bamboo fiber with an emphasis on the extraction and treatment techniques, and their effect on relevant properties. The chemical composition of bamboo fibers has also been thoroughly investigated and presented herein. Current applications and future opportunities for bamboo fibers in various fields have been presented with a focus on research needs. This work can serve as a reference for future research on bamboo fiber

Cardioprotection by cocoa polyphenols and ω-3 fatty acids: A disease-prevention perspective on aging-associated cardiovascular risk

Cardiovascular disease (CVD) remains the leading cause of death today. Many of the biochemical alterations associated with the pathophysiology of CVD can be modified by adequate intakes of bioactive nutrients through a correct diet or supplementation. Recently, there has been growing public and clinical interest in cocoa polyphenols (CPs) and omega-3 (ω-3) fatty acids. A plethora of nutritional intervention trials and experimental studies demonstrates that consumption of these bioactive food compounds is beneficial to promote cardiovascular health. The purpose of this review is to summarize the major cardioprotective effects of CPs and ω-3 fatty acids, providing a scientific rationale for incorporating the combination of these molecules as a nutritional intervention in the prevention of CVD. Although several studies have shown the individual cardioprotective nature of these compounds, a combination treatment with CPs and ω-3 fatty acids may be a promising approach to enhance the preventive value of these molecules and reduce cardiovascular risk factors associated with aging. Therefore, this article also reviews some of the key studies on the interaction between CPs and the metabolism of ω-3 fatty acids

FFAs and QT intervals in obese women with visceral adiposity: Effects of sustained weight loss over 1 year

We evaluated 66 obese patients grouped by waist-to-hip ratio (WHR) into group A (WHR > 0.85, n = 30) and group B (WHR ≤ 0.85, n = 36), before and after 1 yr of diet-induced weight loss compared with 25 nonobese women. Before diet, the longest values of QT intervals and the highest levels of FFA and catecholamines were in group A (P < 0.01). In obese women (both groups), the corrected QT (QTc); interval correlated with plasma FFA (P < 0.01) and catecholamine (P < 0.02) concentrations. After 1 yr of diet, at the same levels of body weight reduction, the decrement of the QTc interval (P < 0.02), FFA (P < 0.01) and catecholamine (P < 0.02) levels were significantly greater in-group A than group B. In multivariate analysis, the decline of the QTc interval after weight loss was associated with changes in plasma FFA independently of changes in WHR and plasma catecholamines. Our data suggest that the QTc interval is tightly correlated with plasma FFA levels; shortening of cardiac repolarization times in the course of long-lasting weight reduction may reduce the risk of ventricular electrical instability, especially in women with abdominal adiposity

Estudio de la potencia como alternativa a los protocolos de laboratorio para el análisis del rendimiento en el ciclismo de carretera.

Los estudios de laboratorio han sido considerados tradicionalmente como el método más idóneo para el análisis del rendimiento en ciclistas. Sin embargo, este tipo de procedimientos está asociado a diversas limitaciones como el elevado coste económico y temporal, la necesidad de recursos humanos cualificados y el acceso a un material técnicoespecífico. Además, este tipo de pruebas no permiten determinar con precisión parámetros máximos y submáximos de rendimiento en una misma sesión. En los últimos años, el uso de potenciómetros se ha extendido ampliamente en los campos profesional y aficionado. Esta herramienta de valoración no está sujeta a condicionantes propios del estudio de otros marcadores de control, tales como la frecuencia cardiaca, la percepción subjetiva del esfuerzo o la velocidad, permitiendo un análisis más preciso de la demanda fisiológica a la que el ciclista está sujeto en todo tipo de condiciones. La posibilidad de estimar parámetros fisiológicos clásicos a través de datos de potencia supone una importante ventana de oportunidad para el análisis del rendimiento por parte de ciclistas, entrenadores y científicos. Esta tesis doctoral analiza retrospectivamente la literatura científica que guarda relación con el entrenamiento a partir de la potencia en el ciclismo de carretera para posteriormente tratar de determinar una fórmula predictiva del consumo máximo de oxígeno a partir de los datos de potencia desarrollados por el ciclista. En los apartados siguientes, se estudia la estrecha relación existente entre el umbral de potencia funcional, el punto de compensación respiratoria, la lactacidemia fija de 4 mmol/L y los umbrales de lactato determinados a través de los métodos Dmax y Dmax modificado. Finalmente, se presenta un análisis exhaustivo de la potencia generada por los ciclistas durante la realización de un evento cicloturista masivo, tratando de proyectar el rendimiento a partir de los datos individuales de potencia. El presente trabajo demuestra la capacidad predictiva y evaluadora del rendimiento que tiene la potencia en el ciclismo de carretera.<br /

SIRT1 activity in peripheral blood mononuclear cells correlates with altered lung function in patients with chronic obstructive pulmonary disease

Background. Oxidative stress is a recognized pathogenic mechanism in chronic obstructive pulmonary disease (COPD). Expression of the NAD+-dependent deacetylase Sirtuin 1 (SIRT1), an antiaging molecule with a key role in oxidative stress response, has been described as decreased in the lung of COPD patients. No studies so far investigated whether systemic SIRT1 activity was associated to decreased lung function in this disease. Methods. We measured SIRT1 protein expression and activity in peripheral blood mononuclear cells (PBMCs) and total oxidative status (TOS), total antioxidant capacity (TEAC), and oxidative stress index (TOS/TEAC) in the plasma of 25 COPD patients, 20 healthy nonsmokers (HnS), and 20 healthy smokers (HS). Results. The activity of SIRT1 was significantly lower in COPD patients compared to both control groups while protein expression decreased progressively (HnS &gt; HS &gt; COPD). TOS levels were significantly lower in HnS than in smoke-associated subjects (COPD and HS), while TEAC levels were progressively lower according (HnS &gt; HS &gt; COPD). In COPD patients, SIRT1 activity, but not protein levels, correlated significantly with both lung function parameters (FEV1/FVC and FEV1) and TEAC. Conclusions. These findings suggest loss of SIRT1-driven antioxidant activity as relevant in COPD pathogenesis and identify SIRT1 activity as a potential convenient biomarker for identification of mild/moderate, stable COPD