Search

The fluctuations in resting‐state beat‐to‐beat blood pressure (BP) are physiologically complex, and the degree of such BP complexity is believed to reflect the multiscale regulation of this critical physiologic process. Hypertension (HTN), one common age‐related condition, is associated with altered BP regulation and diminished system responsiveness to perturbations such as orthostatic change. We thus aimed to characterize the impact of HTN on resting‐state BP complexity, as well as the relationship between BP complexity and both adaptive capacity and underlying vascular characteristics. We recruited 392 participants (age: 60–91 years), including 144 that were normotensive and 248 with HTN (140 controlled‐ and 108 uncontrolled‐HTN). Participants completed a 10‐min continuous finger BP recording during supine rest, then underwent measures of lying‐to‐standing BP change, arterial stiffness (i.e., brachial‐ankle pulse wave velocity), and endothelial function (i.e., flow‐mediated vasodilation). The complexity of supine beat‐to‐beat systolic (SBP) and diastolic (DBP) BP was quantified using multiscale entropy. Thirty participants with HTN (16 controlled‐HTN and 14 uncontrolled‐HTN) exhibited orthostatic hypotension. SBP and DBP complexity was greatest in normotensive participants, lower in those with controlled‐HTN, and lowest in those in uncontrolled‐HTN (p < 0.0005). Lower SBP and DBP complexity correlated with greater lying‐to‐standing decrease in SBP and DBP level (β = −0.33 to −0.19, p < 0.01), greater arterial stiffness (β = −0.35 to −0.18, p < 0.01), and worse endothelial function (β = 0.17–0.22, p < 0.01), both across all participants and within the control‐ and uncontrolled‐HTN groups. These results suggest that in older adults, BP complexity may capture the integrity of multiple interacting physiologic mechanisms that regulate BP and are important to cardiovascular health. [ABSTRACT FROM AUTHOR]

Sandstone is widely used a construction and building material. However, its uniaxial tensile strength (UTS) is not adequately understood. To characterize the uniaxial tensile strength of natural sandstone, three groups of specimens were fabricated for four-point bending, uniaxial compressive, and tensile tests. To characterize the evolution of the stress–strain profiles obtained via these tests, representative expressions were developed in terms of normalized strain and strength. The magnitude of the uniaxial tensile strength exceeded that of the four-point bending strength, indicating that the uniaxial tensile strength cannot be represented by the four-point bending strength. The experimental ratio of uniaxial tensile and compression strength (33–41) was underestimated by the empirical expressions reported in the literature. The suggested correction coefficient for the FBS is 0.25. The compressive modulus (Ec) was generally identical to the experimental results published in the literature, whereas the tensile modulus (Et) was overestimated. The experimental modular ratio, Et/Ec, ranged from 0.12 to 0.14; it was not sensitive to Poisson's ratio, but it increased slightly with the compressive modulus. This work can serve as a reference for computing the load-bearing capacity of sandstone components under tension. [ABSTRACT FROM AUTHOR]

Earthquake damage to freestanding nonstructural components has occurred in past earthquakes. Ceramic vase is one of the most vulnerable freestanding nonstructural components in museums, residential, and historical buildings. To investigate the seismic performance of a freestanding vase, shaking table tests were conducted, where four motions, consisting of two historic and two artificial ones, were selected and generated. The kinetic friction coefficient was acquired with a slow-pull test, which was used to define the possible response modes. The rocking and sliding responses of the vase were observed by accelerometers and high-speed camera. Results showed that the response mode of the vase was highly dependent on the input peak acceleration, i.e., the higher the peak acceleration, the larger the peak and residual displacements and rocking angles. In addition, the dynamic response varies with the excitation of different input motions, indicating that the frequency contents of the input motion also affect the rocking intensity. Generally, the experimental kinetic friction coefficient from the shaking table test matched the one from the slow-pull test closely, demonstrating that the two approaches were reasonable and accurate enoughand can be accepted. Using the philosophy of the second generation of performance-based earthquake engineering, damage modes, performance levels, and fragility curves were defined and generated on account of crack intensity, repair actions, and rocking angles, respectively. These efforts are also beneficial for the seismic evaluation of the freestanding objects in building structures. [ABSTRACT FROM AUTHOR]

Abstract Background Streptococcus iniae (S. iniae) is a major pathogen that causes considerable morbidity and mortality in cultured fish worldwide. The pathogen's ability to adapt to the host affects the extent of infection, hence understanding the mechanisms by which S. iniae overcomes physiological stresses during infection will help to identify potential virulence determinants of streptococcal infection. Grow S. iniae under iron-restricted conditions is one approach for identifying host-specific protein expression. Iron plays an important role in many biological processes but it has low solubility under physiological condition. Many microorganisms have been shown to be able to circumvent this nutritional limitation by forming direct contacts with iron-containing proteins through ATP-binding cassette (ABC) transporters. The ABC transporter superfamilies constitute many different systems that are widespread among living organisms with different functions, such as ligands translocation, mRNA translation, and DNA repair. Results An ABC transporter system, named as mtsABC (metal transport system) was cloned from S. iniae HD-1, and was found to be involved in heme utilization. mtsABC is cotranscribed by three downstream genes, i.e., mtsA, mtsB, and mtsC. In this study, we cloned the first gene of the mtsABC transporter system (mtsA), and purified the corresponding recombinant protein MtsA. The analysis indicated that MtsA is a putative lipoprotein which binds to heme that can serve as an iron source for the microorganism, and is expressed in vivo during Kunming mice infection by S. iniae HD-1. Conclusions This is believed to be the first report on the cloning the ABC transporter lipoprotein from S. iniae genomic DNA. Together, our data suggested that MtsA is associated with heme, and is expressed in vivo during Kunming mice infection by S. iniae HD-1 which indicated that it can be a potential candidate for S. iniae subunit vaccine.

In this study, cement composites were fabricated with various contents of added nano-silica (NS) and multi-walled carbon nanotubes (MWNTs). The compressive and flexural strengths of the resultant cement composites were examined. To explore the microstructures and MWNT distribution, electrical conductivity tests, and scanning electron microscopy were conducted. In addition, the strength results were analyzed based on thermal analysis and porosity evaluations. The electrical conductivity results indicated that MWNTs were satisfactorily distributed in the cement composites. In the mechanical strength tests, the composite with a 0.6% MWNT and 5% NS content and another with a 0.3% MWNT and 5% NS content yielded enhancements in the compressive and flexural strengths of 17.2% and 52% compared with the control samples, respectively. However, composites containing relatively large amounts of both NS and MWNTs showed degradation in the mechanical strength. The enhancement or degradation of the strength was supported by porosity evaluations and thermal analysis results. In particular, the degradation of the strength due to the incorporation of large amounts of both MWNTs and NS was explained by thermogravimetric analysis, which indicated a limited generation of calcium silicate hydrate (C-S-H) hydration products. The lower generation of C-S-H was likely due to the dense microstructure of MWNT/NS-incorporated cement hindering the reactions between calcium hydroxide and the NS. [ABSTRACT FROM AUTHOR]