Influence of Impregnation of Recycled Concrete Aggregate on the Selected Properties of Concrete

The paper focuses on investigating the effect of impregnation of recycled concrete aggregate on the mechanical and durability properties of concrete using this aggregate. Cement paste, limewater and diluted water glass were used to impregnate the aggregate. Both a single impregnation and a double impregnation using two different solutions were carried out. A total of four groups of concrete series, with two values of w/c ratio (0.45 and 0.60), were made. Concrete made using the impregnated aggregate was tested and the results were compared with those of concrete made using untreated recycled aggregate of the same kind. The results indicate that impregnation of aggregate improves the mechanical properties of concrete in many cases but reduces its resistance to cyclic freezing and thawing. Furthermore, in the case of impregnation with two solutions, the order in which the impregnants are applied influences the effect obtained. Using the results received, the impregnation methods were ranked in order from best to worst. The best impregnation method proved to be with cement paste, followed by diluted water glass, while the worst results were obtained with limewater, followed by diluted water glass.     

Sarcolemmal cardiac K(ATP) channels as a target for the cardioprotective effects of the fluorine-containing pinacidil analogue, flocalin

BACKGROUND AND PURPOSE

A class of drugs known as K_ATP-channel openers induce cardioprotection. This study examined the effects of the novel K_ATP-channel opener, the fluorine-containing pinacidil derivative, flocalin, on cardiac-specific K_ATP-channels, excitability of native cardiac myocytes and on the ischaemic heart.

EXPERIMENTAL APPROACH

The action of flocalin was investigated on: (i) membrane currents through cardiac-specific K_ATP-channels (I_KATP) formed by K_IR6.2/SUR2A heterologously expressed in HEK-293 cells (HEK-293_6.2/2A); (ii) excitability and intracellular Ca²⁺ ([Ca²⁺]_i) transients of cultured rat neonatal cardiac myocytes; and (iii) functional and ultrastructural characteristics of isolated guinea-pig hearts subjected to ischaemia-reperfusion.

KEY RESULTS

Flocalin concentration-dependently activated a glibenclamide-sensitive I_KATP in HEK-293_6.2/2A cells with an EC₅₀ = 8.1 ± 0.4 µM. In cardiac myocytes, flocalin (5 µM) hyperpolarized resting potential by 3–5 mV, markedly shortened action potential duration, reduced the amplitude of [Ca²⁺]_i transients by 2–3-fold and suppressed contraction. The magnitude and extent of reversibility of these effects depended on the type of cardiac myocytes. In isolated hearts, perfusion with 5 µmol·L⁻¹ flocalin, before inducing ischaemia, facilitated restoration of contraction during reperfusion, decreased the number of extrasystoles, prevented the appearance of coronary vasoconstriction and reduced damage to the cardiac tissue at the ultrastructural level (state of myofibrils, membrane integrity, mitochondrial cristae structure).

CONCLUSION AND IMPLICATIONS

Flocalin induced potent cardioprotection by activating cardiac-type K_ATP-channels with all the benefits of the presence of fluorine group in the drug structure: higher lipophilicity, decreased toxicity, resistance to oxidation and thermal degradation, decreased metabolism in the organism and prolonged therapeutic action.     

Substituting Brown Rice for White Rice to Lower Diabetes Risk: A Focus-Group Study in Chinese Adults

Whole-grain products, such as brown rice, have been associated with lower risk of diabetes. However, information is lacking on the acceptability of substituting brown rice for white rice. This study assessed the awareness and acceptability of brown rice in Chinese adults, and examined the feasibility of introducing brown rice into the diet through a large, long-term randomized clinical trial to lower risk of type 2 diabetes. Thirty-two Chinese adults residing in Shanghai participated in this quantitative and qualitative study using questionnaires and focus-group discussions. Most participants (30 of 32) consumed white rice daily and only a few (n=8) had tried brown rice previously. Before tasting, most participants considered brown rice inferior to white rice in terms of taste and quality. However, after tasting brown rice and learning about its nutritional value, the majority indicated greater willingness to consume brown rice. Main barriers to acceptance were the perception of rough texture and unpalatable taste, as well as higher price. All participants suggested that large-scale promotion was needed to change societal attitudes toward brown rice. In addition, most participants (27 of 32) expressed willingness to participate in a future long-term brown rice intervention study. These results provide valuable information for the design of the future brown rice intervention trial and highlight the importance of increasing awareness about the nutritional value of brown rice.