Tensile Properties and Fracture Behavior of Aluminum Alloy Foam Fabricated from Die Castings without Using Blowing Agent by Friction Stir Processing Route

Al foam has been used in a wide range of applications owing to its light weight, high energy absorption and high sound insulation. One of the promising processes for fabricating Al foam involves the use of a foamable precursor. In this study, ADC12 Al foams with porosities of 67%–78% were fabricated from Al alloy die castings without using a blowing agent by the friction stir processing route. The pore structure and tensile properties of the ADC12 foams were investigated and compared with those of commercially available ALPORAS. From X-ray computed tomography (X-ray CT) observations of the pore structure of ADC12 foams, it was found that they have smaller pores with a narrower distribution than those in ALPORAS. Tensile tests on the ADC12 foams indicated that as their porosity increased, the tensile strength and tensile strain decreased, with strong relation between the porosity, tensile strength, and tensile strain. ADC12 foams exhibited brittle fracture, whereas ALPORAS exhibited ductile fracture, which is due to the nature of the Al alloy used as the base material of the foams. By image-based finite element (FE) analysis using X-ray CT images corresponding to the tensile tests on ADC12 foams, it was shown that the fracture path of ADC12 foams observed in tensile tests and the regions of high stress obtained from FE analysis correspond to each other. Therefore, it is considered that the fracture behavior of ADC12 foams in relation to their pore structure distribution can be investigated by image-based FE analysis.     

Combined effect of angiotensin II receptor blocker and either a calcium channel blocker or diuretic on day-by-day variability of home blood pressure: the Japan Combined Treatment With Olmesartan and a Calcium-Channel Blocker Versus Olmesartan and Diuretics Randomized Efficacy Study

Day-by-day home blood pressure (BP) variability (BPV) was reported to be associated with increased cardiovascular risk. We aimed to test the hypothesis that the angiotensin II receptor blocker/calcium-channel blocker combination decreases day-by-day BPV more than the angiotensin II receptor blocker/diuretic combination does and investigated the mechanism underlying the former reduction. We enrolled 207 hypertensive subjects treated with olmesartan monotherapy for 12 weeks. The subjects were randomly assigned to treatment with hydrochlorothiazide (n = 104) or azelnidipine (n = 103) for 24 weeks. Home BP was taken in triplicate with a memory-equipped device in the morning and evening, respectively, for 5 consecutive days before each visit. Visits occurred at 4-week intervals. Home BPV was defined as within-individual SD of the 5-day home BP. Arterial stiffness was assessed by aortic pulse wave velocity at baseline and 24 weeks later. The reductions in home systolic BP were similar between the 2 groups, whereas the SD of home systolic BP decreased more in the azelnidipine group than in the hydrochlorothiazide group during the follow-up period (follow-up mean: 6.3 versus 7.1 mm Hg; P = 0.007). In the azelnidipine group, the change in aortic pulse wave velocity was independently associated with the change in SD of home systolic BP (regression coefficient ± SE = 0.79 ± 0.37; P = 0.036). This study demonstrated that the angiotensin II receptor blocker/calcium-channel blocker combination improved home BPV in addition to home BP reduction and that the reduction in home BPV was partly attributable to the arterial stiffness reduction by this combination.     

Nighttime Home Blood Pressure and the Risk of Hypertensive Target Organ Damage

In ambulatory blood pressure (BP) monitoring, nighttime BP has a superior ability to predict hypertensive target organ damage than awake BP. We evaluated whether nighttime BP, assessed by a home BP monitor, was associated with hypertensive target organ damage. We measured clinic BP, out-of-clinic BP including nighttime home BP, and the urinary albumin:creatinine ratio (UACR) in 854 patients who had cardiovascular risk factors. Nighttime home BP was measured at 2:00, 3:00, and 4:00 am, in addition to clinic, awake ambulatory, nighttime ambulatory, and awake home BP. Nighttime home systolic BP (SBP) was slightly higher than nighttime ambulatory SBP (difference, 2.6 mm Hg; P<0.001). Clinic (r=0.186), awake ambulatory (r=0.173), nighttime ambulatory (r=0.194), awake home (r=0.298), and nighttime home (r=0.311) SBPs were all associated with log-transformed UACR (all P<0.001). The correlation coefficient for the relationship between nighttime home SBP and log-transformed UACR was significantly greater than that for the relationship between nighttime ambulatory SBP and log-transformed UACR (P<0.001). The goodness of fit of the association between SBP and UACR was improved by adding nighttime home SBP to the other SBPs (P<0.001). Nighttime home diastolic BP also improved the goodness-of-fit of the association between diastolic BP and UACR (P=0.001). Similar findings were observed for the left ventricular mass index in the subgroup (N=594). In conclusion, nighttime home BP is slightly different from (but comparable to) nighttime ambulatory BP. The addition of nighttime home BP to other BP measures improves the association of BP with hypertensive target organ damage.