Search

This paper contributes to the expanding knowledge base on nanomaterial-enhanced cementitious composites, offering valuable insights for developing high-performance, sustainable concrete solutions. The study assessed the effects of three different types of nanomaterials—nano clay (NC), nano silica (NS), and nano cellulose (NCel)—on the compressive strength of high-early-strength concrete (HESC) through both experimental studies and a 23 factorial design. Incorporating nanomaterials into the HESC matrix led to a decrease in workability, with NCel demonstrating the least impact on this property across all studied replacement percentages. All HESC mixes containing nanomaterials exhibited higher compressive strength than the control mix (M mix) across all ages. The optimal percentages for compressive strength enhancement were 4.5% NC (33.43% increase at 3 days, 22.29% at 7 days, and 12.15% at 28 days), 4.5% NS (20.12%, 11.14%, and 4.89% respectively), and 0.0375% NCel (34.91%, 25.76%, and 13.46% respectively). The highest compressive strength was observed in the hybrid mix containing 4.5% NC and 0.0375% NCel, yielding strength enhancements of 35.7%, 26%, and 12.75% compared to the M mix. Statistical analysis indicated that nano cellulose had the most significant contribution to enhancing compressive strength, followed by nano clay. The mathematical models derived from the statistical analyses provide a reliable means of predicting the compressive strength of HESC at 3, 7, and 28 days based on nanomaterial content. Contour plots illustrated the optimization of compressive strength across different nanomaterial contents at each age. In summary, the findings underscore the potential of waste-derived nanomaterials to enhance the performance of HESC, paving the way for innovative waste utilization strategies in construction. The study emphasizes the importance of reducing curing times, improving structural durability, and minimizing the environmental impact associated with concrete production. [ABSTRACT FROM AUTHOR]

This paper contributes to the debate on the evolution of living standards in preindustrial England. It emphasizes the need to depart from the approach of focusing only on the time paths of observables, like income per capita and population size, in order to assess the validity of Malthusian predictions. It first constructs a Malthusian model and then develops a robust algorithm for identifying the latent forces that have shaped aggregate outcomes in the preindustrial era. The analysis suggests the existence of two distinct Malthusian regimes in preindustrial England: a survival-driven regime, where mortality is the main latent force in economic-demographic interactions, and a later technology-driven regime that emerges after the mid-fifteenth century and is characterized by both population and productivity growth but stable mortality and long-run stagnation in per capita income. The paper discusses the role of various historical accidents (e.g., the Black Death, the discovery of the New World, the English Reformation) in triggering the emergence of the technology-driven regime, and it also highlights some mediating mechanisms through which subsequent productivity growth may have been sustained. The existence of long-run stagnation in income per capita in England through the mid-seventeenth century, despite the technological dynamism of the early modern period, is consistent with the predictions of Unified Growth Theory. [ABSTRACT FROM AUTHOR]

Microbial electrolysis cells (MECs) have rapidly evolved as a promising technology to produce hydrogen from organic sources through anodic and cathodic electrochemical reactions. The MEC cathode has a rate-limiting effect on the hydrogen evolution reaction (HER) that necessitated the usage of expensive metal catalysts. Biocathode defined as microorganisms attached to the cathode is a promising alternative to abiotic catalysts for hydrogen production. Sulphate-reducing bacteria (SRB) are a potential source for biocathode enrichment. This study unlike previous literature mainly focused on the detailed characterization of autotrophic SRB-based biocathode MEC which produces hydrogen from a mixed culture source. The HER of MEC was optimized prior to the characterization step by adjusting sodium sulphate concentration, hydrogen feeding step during enrichment and adjusting pH of the media. Hydrogen production rate drastically increased from 0.15 m3/(m3 d) in the mixed culture-catalysed cathode to 1.53 m3/(m3 d) after three months of enrichment, while the cathodic charge transfer resistance decreased substantially from 463 to 1.8 Ω over the same enrichment period. DNA of the microbial communities attached to the biocathodes was then extracted at different enrichment times, and the dominant communities were identified using metagenomic amplicon sequencing. Moreover, Desulfovibrio was detected as the dominant genus in the enriched biocathodes through the enrichment stages. The findings of this study enable development of less-complex system for biocathode-based hydrogen production from any mixed culture sources. This in turn facilitates future commercial-scale implementation of MEC technology. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to describe the nonlinear behaviour of geomaterials within the principles of thermodynamics. The main components of this contribution are (1) a new method to estimate the properties of minerals subjected to the non-hydrostatic compression in diamond anvil cell using the finite strain theory is introduced and (2) a proper measure of deformation that applies to a wide range of minerals is identified. This research work shows that the logarithmic (Hencky) strain produces a good agreement with experiments for a wide range of materials. [ABSTRACT FROM AUTHOR]

An attempt has been made to investigate the effect of phosphating time and vanadium additive on the anticorrosion and surface properties of ambient temperature zinc phosphate coatings. Zinc phosphate coatings with different phosphating times and vanadium concentrations were applied to low carbon steel samples. A potentiostatic polarization test in 3.5 wt% NaCl solution was carried out to investigate the electrochemical properties of coated samples. Field emission scanning electron microscopy, energy-dispersive spectroscopy, and atomic force microscopy were utilized to evaluate the microstructure, chemistry and roughness of coatings. Surface properties such as wettability, surface tension, and work of adhesion were measured. Results indicate that the sample which was immersed for 30 min in the phosphating bath exhibits the lowest corrosion current density, one tenth of bare steel, due to formation of a compact coating while having a low number of microcracks. Addition of 500 ppm vanadium to the coating in a secondary bath decreases the corrosion rate of zinc phosphate coating remarkably, by almost 80%. Microstructural results reveal that vanadium-rich precipitates are formed and enhance the coating coverage on the steel substrate. Vanadium addition increases the surface roughness, surface free energy, and work of adhesion of the phosphate coating. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the mechanism of load transfer in unidirectional polymeric composites material with triangular fibers in the presence of broken fibers. It is assumed that all fibers with triangle-cross section lie in a same direction while loaded by a load at infinity. In previous studies, the behavior of polymeric matrix is assumed elastic, while the behavior of most polymeric matrix is elastic-perfect plastic. For this purpose, equilibrium equations by use of shear-lag theory have been derived and by proper using boundary and boundness conditions, displacement field and stress distribution were computed. Finally, the results of stress concentrations and di shear stress, at neighbor of broken fibers for carbon-epoxy composite material were extracted and compared with composite materials with circular fibers. The analytical results are compared to the detailed finite element values. A close match is observed between the two methods. [ABSTRACT FROM AUTHOR]

Background: Overweight and obesity has been suggested to be well correlated with altered levels of pro-inflammatory cytokines. Aim: The purpose of this study is to assess the relationship of body fat mass (BFM), body fat percentage (BFP) and leptin levels with peripheral blood mononuclear cells (PBMCs) cytokines among obese and overweight adults. Methods: Eighty-two overweight and obese individuals were divided into two BMI-category groups (BMI <30 and BMI ≥30 kg/m) in this study. Balanced blocked randomization was used based on their sex and BMI ranges. Fasting blood samples, PBMCs cytokines, leptin and anthropometric indices were measured and PBMCs were cultured. Results: Mean of leptin concentrations were 23.14 ± 4.07 and 28.25 ± 4.35 pg/ml among individuals with BMI <30 and BMI ≥30 kg/m, respectively. The mean values of anthropometric measurements (all P < 0.001), the concentrations of TNF-α ( P = 0.028) and IFN-γ ( P = 0.029) were significantly higher among obese individuals. BFP had a significant positive correlation with leptin ( P < 0.001, r = 0.445) and TGF-β ( P = 0.03, r = 0.243). BFM has significant positive correlation with leptin ( P < 0.001, r = 0.521). Leptin had a positive significant correlation with IFN-γ ( p = 0.03, r = 0.251). Conclusions: Regarding these results, we proved that BFP, BFM and leptin levels have significant correlations with some PBMC cytokines. Focusing on such strategies may lead to promises for alleviating obesity and its co-morbidities. [ABSTRACT FROM AUTHOR]

Background:The mechanisms by which stress hormones impact triple-negative breast cancer (TNBC) etiology and treatment are unclear. We have previously shown that stress hormones, cortisol, and catecholamines induce rapid DNA damage and impact DNA repair in NIH 3T3 fibroblasts. This study investigates whether stress hormones increase DNA damage in breast cancer cells and if this impacts drug efficacy.Methods:We first screened a panel of 39 breast cancer cell lines for expression of adrenergic and glucocorticoid receptors and examined if stress hormones induce DNA damage and alter cell cycle regulation in vitro. A TNBC xenograft model was used to assess the impact of restraint stress on tumour growth and chemosensitivity to paclitaxel.Results:We found that stress hormones induced DNA damage, phosphorylation of ATR, which was accompanied by an up-regulation of the G1 cell kinase inhibitor p21 and a cell cycle halt of TNBCs in the G1 phase. p21 knockdown abrogated G1 arrest by stress hormones. We also demonstrated that stress significantly decreased efficacy of paclitaxel.Conclusion:We describe a novel mechanism through which stress hormones can induce drug resistance to paclitaxel, which may have profound implications for treating drug resistance in patients with TNBC. [ABSTRACT FROM AUTHOR]

Let $$G$$ be a group and let $$\mathrm{Aut}(G)$$ be the full automorphism of $$G$$ . The purpose of this paper was to consider finite $$p$$ -groups $$G$$ for which $$|G|=|\mathrm{Aut}(G)|$$ . We classify groups satisfying this condition among those in certain classes of finite $$p$$ -groups. [ABSTRACT FROM AUTHOR]

The corrosion inhibition effect of fluconazole (FLU) was investigated on steel in 1 M hydrochloric acid solution. Weight loss measurements and atomic force microscope analysis were utilized to investigate the corrosion inhibition properties and film formation behaviour of FLU. Quantum chemical approach was also used to calculate some electronic properties of the molecule in neutral and protonated form in order to find any correlation between the inhibition effect and molecular structure of FLU molecule. The results showed that FLU can act as a good corrosion inhibitor for steel in hydrochloric acid solution at different temperatures and it can inhibit steel corrosion up to 95%. The adsorption followed the Langmuir isotherm and the thermodynamic parameters were also determined and discussed. Quantum chemical studies showed that in adsorption process of FLU molecules, nitrogen and oxygen atoms and benzene ring act as active centres. [ABSTRACT FROM AUTHOR]

The St-37 type steel substrates were pretreated with Cr(VI) and Cr(III) conversion coatings where the latter was then post-treated with Co(II) and Ni(II) chemical treatments. The epoxy coatings containing 3.5 wt% nano-sized ZnO particles were applied over the chemically treated steel samples. The corrosion resistance of the samples was studied by a DC polarization technique. A scanning electron microscope (SEM) was utilized to investigate the morphology of the pretreated and post-treated samples. Electrochemical impedance spectroscopy (EIS) was utilized to investigate the corrosion resistance of the epoxy nanocomposites for different immersion times in 3.5 wt% NaCl solution. The adhesion strengths of the coatings were measured before and after 120 days of immersion in the corrosive electrolyte using a pull-off test. The cathodic delamination (CD) of the painted samples was also investigated. Results showed that conversion coatings can significantly increase the corrosion resistance and adhesion strength of the epoxy coating on the steel, and also reduce the rate of CD in comparison with an untreated sample. The adhesion strength and corrosion resistance of the epoxy coating on the Cr(III) pretreated samples were significantly greater than on the Cr(VI) sample. The increase in adhesion strength and corrosion resistance was more pronounced on the samples that were post-treated with Co(II) and Ni(II) chemical treatments. The cathodic disbonded areas of the Cr(III)-Co(II) and Cr(III)-Ni(II) post-treated samples were significantly lower than the Cr(III) and Cr(VI) pretreated samples. Results showed that Cr(III)-based conversion coatings can improve the anticorrosion performance and reduce CD compared with those with Cr(VI). [ABSTRACT FROM AUTHOR]

Let G be a group and let Autc(G) be the group of central auto-morphisms of G. We say that a subgroup H of a group G is c-characteristic if α(H) = H for all α ϵ Autc(G). We say that a group G is c-characteristically simple group if it has no non-trivial c-characteristic subgroup. If every subgroup of G is c-characteristic then G is called co-Dedekindian group. In this paper we characterize c-characteristically simple groups. Also if G is a direct product of two groups A and B we study the relationship between the co-Dedekindianness of G and the co-Dedekindianness of A and B. We prove that if G is a co-Dedekindian finite non-abelian group, then G is Dedekindian if and only if G is isomorphic to Q8 where Q8 is the quaternion group of order 8. [ABSTRACT FROM AUTHOR]

Objective:We evaluated the effect of late preterm delivery (34 to 36 weeks) on hospital mortality of infants with congenital heart defects (CHDs).Study Design:Retrospective record review of infants with major CHD born at or after to 34 weeks, cared for in a single tertiary perinatal center between 2002 and 2009. Factors associated with death before discharge from the hospital were ascertained using univariate and multivariate analyses.Result:Of the 753 infants with CHD, 117 were born at late preterm. Using logistic regression analysis, white race (OR; 95% CI) (0.60; 0.39 to 0.95), late preterm delivery (2.70; 1.69 to 4.33), and need for intubation in the delivery room (3.15; 1.92 to 5.17) were independently associated with hospital death.Conclusion:Late preterm birth of infants with major CHDs was independently associated with increased risk of hospital death compared with delivery at more mature gestational ages. [ABSTRACT FROM AUTHOR]

This study was carried out in metropolitan Kuwait with a sound level meter to assess peak hour and off-peak hour noise level. In local/collector streets, noise ranged between 56.0 to 79.2 dBA and 55.3 to 76.4 dBA; in arterial streets, 62.3 to 89.2 dBA and 59.6 to 78.9 dBA; and in freeways, 66.7 to 94.8 dBA and 64.9 to 89.1 dBA during peak and off-peak hour respectively. Values were higher than their prescribed standards which may pose a significant impact on quality of life. Findings of this research have shown that the level of traffic-generated noise pollution in Kuwait urban area is high enough to adversely affect the human health and well-being of its residents. Over 1,400 subjects responded to a randomly administered survey that assessed the physical health, personal well-being, and mental health. People residing in neighborhoods exposed to higher noise levels have significantly higher stress and noise annoyance levels and also adversely affected their sense of well-being. In the responder analysis, those people living in quiet neighborhoods had significantly higher mean scores in general health (35 points higher, p < 0.05), sense of vitality (30 points higher, p < 0.05), and mental health (20 points higher, p < 0.05) when compared to the other group. In addition, the component scores of stress and noise sensitivity for the participants living in quiet neighborhoods had significantly lower values (30 points lower and 59 points lower, respectively) than that of the participants living in noisy neighborhood. With the rapid expansion of the infrastructures in metropolitan Kuwait, it is virtually definite that traffic noise will shortly assume a dangerous dimension, and will be a ground of escalating fear for both the public and liable policy-makers. The quality of life in metropolitan Kuwait will certainly be negatively affected. [ABSTRACT FROM AUTHOR]

Let G be a non-abelian finite p-group such that | Z( G)| = p. In this paper we prove that each maximal subgroup M ≠ C( Z( G)) is non-abelian and has cyclic centre. [ABSTRACT FROM AUTHOR]

Effect of ZnO nanoparticles particles on the mechanical properties and the curing behavior of an epoxy nanocomposite were studied. Nanocomposites were prepared using different loadings of pre-dispersed ZnO nanoparticles having an average size of 40 nm. The surface topography and morphology of the nanocomposites were studied using atomic force microscope (AFM). The mechanical properties of nanocomposites were studied using analytical techniques including dynamic mechanical thermal analysis and micro-Vickers hardness. Effects of ZnO nanoparticles on the curing behavior of these nanocomposites were investigated utilizing isothermal and non-isothermal differential scanning calorimeter techniques. In addition, chemical compositions of coatings containing different ZnO nanoparticles contents were studied using a Fourier transform inferred. It was found that, ZnO nanoparticles can effectively influence the mechanical properties of epoxy coating. In addition, lower curing degrees, and therefore crosslinking density of epoxy coating including higher ZnO nanoparticles were obtained. This effect was completely different at low and high loadings of the particles. [ABSTRACT FROM AUTHOR]

The anticorrosion performance of zinc aluminum phosphate pigment was evaluated using electrochemical impedance spectroscopy, the electrochemical noise method and DC polarization. The results of the electrochemical tests revealed the superiority of zinc aluminum phosphate in comparison with zinc phosphate in terms of inhibitive characteristics. The trend and magnitude of resistances and current density plus the appearance of the impedance spectra and the power spectral density of the current noise indicated deposition of a layer on the surface of samples exposed to ZPA extract. SEM/EDX analysis confirmed the precipitation. [ABSTRACT FROM AUTHOR]

Background:Chronically elevated interleukin-6 (IL-6) is implicated in obesity-associated pathologies, where a proportion of this cytokine is derived from adipose tissue. Proinflammatory prostaglandins, which regulate this cytokine elsewhere, are also produced by this tissue.Objective:To investigate whether constitutively active cyclooxygenase (COX)/prostaglandin (PG) pathway in white adipose tissue (WAT) is responsible for basal IL-6 production.Design:The effect of acetylsalicylic acid (ASA), an inhibitor of COX, on IL-6 was assessed in human subjects and mice. COX, downstream PG synthase (PGS) activity and PG receptor signalling were determined in subcutaneous (SC), gonadal (GN) WAT and adipocytes.Methods and Results:In obese humans, low-dose ASA (150 mg day−1 for 10 days) inhibited systemic IL-6 and reduced IL-6 release from SC WAT ex vivo (0.2 mM). Similarly, in mice, ASA (0.2 and 2.0 mg kg−1) suppressed SC WAT 6-keto-PGF1α (a stable metabolite of prostacyclin) and IL-6 release. Although both COX isoforms are comparably expressed, prostacyclin synthase expression is higher in GN WAT, with levels of activity correlating directly with IL-6. Both ASA (5 mM) and NS-398 (COX-2 selective inhibitor 1 μM), but not SC-560 (COX-1 selective inhibitor 1 μM), attenuated IL-6 release from murine WAT in vitro and abolished its depot differences. Prostacyclin receptor (IP) and, to a lesser extent, PGE2 (EP2 and EP4) receptor agonists elevated the release of IL-6 from adipocytes.Conclusions:In adipose tissue, constitutive COX-2-coupled prostacyclin triggers the release of basal IL-6, which in obese subjects is significantly dampened by ASA ingestion, thus offering a novel, modifiable pathway to regulate the potentially pathological component of this cytokine.International Journal of Obesity (2008) 32, 1807–1815; doi:10.1038/ijo.2008.190; published online 4 November 2008 [ABSTRACT FROM AUTHOR]

Introduction:Birth of very low birth weight (VLBW) infants outside subspecialty perinatal centers increases risk for death and major morbidities.Objective:The purpose of this study is to evaluate barriers to utilizing a regional perinatal center for the birth of VLBW infants to mothers not living in the immediate vicinity of the center.Methods:We conducted a retrospective cohort study of VLBW infants residing in the catchment area of a community level II, Specialty Neonatal Unit (SN) admitted to a Regional Subspecialty Neonatal Intensive Care Unit (RC) between January 1999 and December 31, 2004. Maternal demographics and prenatal care as well as outcomes were compared by place of birth.Results:Out of 98 VLBW infants admitted to the RC, 49 (50%) were delivered outside the RC (out-born) and 49 (50%) were born at the RC (in-born). There was no statistical difference in insurance coverage, race, gestational age, severity of illness or maternal demographic factors between out-born and in-born infants. Less than adequate prenatal care rather than distance of maternal residence from the RC was associated with birth outside the RC. Adjusting for prenatal care, distance of residence from the RC increased the risk for delivering outside the center in the subset of mothers insured by Medicaid.Conclusions:Mothers of VLBW infants who received less than adequate prenatal care and did not live in the vicinity of a subspecialty center had an increased risk for delivery outside that center compared to those with adequate care. Appropriate place of birth for VLBW infants to low-income mothers may be influenced by the distance of their residence to an RC.Journal of Perinatology (2006) 26, 210–214. doi:10.1038/sj.jp.7211488; published online 23 March 2006 [ABSTRACT FROM AUTHOR]

Aims/hypothesis: Diets rich in n-3 polyunsaturated fatty acids, namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), protect against insulin resistance and obesity in rodents and increase insulin sensitivity in healthy humans. We tested whether the anti-diabetic effects of EPA and DHA involve enhanced production of the endogenous insulin sensitiser, adiponectin. Methods: We studied the effects, in an obesity-promoting high-fat diet, of partial replacement of vegetable oils by EPA/DHA concentrate (6% EPA, 51% DHA) over a 5-week period in adult male C57BL/6J mice that either had free access to food or had their food intake restricted by 30%. At the end of the treatment, systemic markers of lipid and glucose metabolism and full-length adiponectin and leptin were measured. Adiponectin (Adipoq) and leptin (Lep) gene expression in dorsolumbar and epididymal white adipose tissue (WAT) and isolated adipocytes was quantified and adipokine production from WAT explants evaluated. Results: In mice with free access to food, plasma triacylglycerols, NEFA, and insulin levels were lower in the presence of EPA/DHA, while glucose and leptin levels were not significantly altered. Food restriction decreased plasma triacylglycerols, glucose, insulin and leptin, but not adiponectin. EPA/DHA increased plasma adiponectin levels, independent of food intake, reflecting the stimulation of Adipoq expression in adipocytes and the release of adiponectin from WAT, particularly from epididymal fat. Expression of Lep and the release of leptin from WAT, while being extremely sensitive to caloric restriction, was unaltered by EPA/DHA. Conclusions/interpretation: Intake of diets rich in EPA and DHA leads to elevated systemic concentrations of adiponectin, largely independent of food intake or adiposity and explain, to some extent, their anti-diabetic [ABSTRACT FROM AUTHOR]