Effective Stress in Unsaturated Soils: A Thermodynamic Approach Based on the Interfacial Energy and Hydromechanical Coupling

In recent years, the effective stress approach has received much attention in the constitutive modeling of unsaturated soils. In this approach, the effective stress parameter is very important. This parameter needs a correct definition and has to be determined properly. In this paper, a thermodynamic approach is used to develop a physically-based formula for the effective stress tensor in unsaturated soils. This approach accounts for the hydro-mechanical coupling, which is quite important when dealing with hydraulic hysteresis in unsaturated soils. The resulting formula takes into account the role of interfacial energy and the contribution of air?Cwater specific interfacial area to the effective stress tensor. Moreover, a bi-quadratic surface is proposed to represent the contribution of the so-called suction stress in the effective stress tensor. It is shown that the proposed relationship for suction stress is in agreement with available experimental data in the full hydraulic cycle (drying, scanning, and wetting).     

Synthesis and Characterization of a Fluorescent Water-Borne Polyurethane Based on a Novel Naphthalimide Dye

A waterborne-polyurethane (WPU) dye, based on the fluorescent dye 4-diamino propane-N-allyl-1,8- naphthalimide (WPU-DAN), was synthesized by attaching 4-diamino propane-N-allyl-1,8- naphthalimide (DAN) onto both ends of the polyurethane (PU) chains according to a prepolymer?ionomer process. The synthetic process was confirmed by Fourier transform infrared spectroscopy (FTIR) and UV-visible absorption. The glass transition temperature, molecular weight and average particle sizes were measured. The glass transition temperatures of WPU and WPU-DAN were 46.6 and 49.8°C, respectively. In addition, the particle size distributions of WPU-DAN and WPU were 140 and 134 nm, respectively. The thermal behaviour of WPU-DAN showed improvement compared to WPU. The fluorescence intensity of WPU-DAN was enhanced more than DAN due to the naphthalimide groups attached to the chains, and the fluorescence intensity of WPU-DAN and DAN were increased by increasing temperature. Moreover, the fluorescence intensity of WPU-DAN emulsion was stable during 30 days and no loss of fluorescence intensity occurred for these days.     

Nonlinear integral resonant controller for vibration reduction in nonlinear systems

A new nonlinear integral resonant controller (NIRC) is introduced in this paper to suppress vibration in nonlinear oscillatory smart structures. The NIRC consists of a first-order resonant integrator that provides additional damping in a closed-loop system response to reduce high-amplitude nonlinear vibration around the fundamental reso-nance frequency. The method of multiple scales is used to obtain an approximate solution for the closed-loop system. Then closed-loop system stability is investigated using the resulting modulation equation. Finally, the effects of different control system parameters are illustrated and an approximate solution response is verified via numerical simulation results. The advantages and disadvantages of the proposed controller are presented and extensively discussed in the results. The controlled system via the NIRC shows no high-amplitude peaks in the neighboring frequencies of the resonant mode, unlike conventional second-order compensation methods. This makes the NIRC controlled system robust to excitation frequency variations.     

High-throughput biophysical measurement of human red blood cells

This paper reports a microfluidic system for biophysical characterization of red blood cells (RBCs) at a speed of 100-150 cells s(-1). Electrical impedance measurement is made when single RBCs flow through a constriction channel that is marginally smaller than RBCs' diameters. The multiple parameters quantified as mechanical and electrical signatures of each RBC include transit time, impedance amplitude ratio, and impedance phase increase. Histograms, compiled from 84,073 adult RBCs (from 5 adult blood samples) and 82,253 neonatal RBCs (from 5 newborn blood samples), reveal different biophysical properties across samples and between the adult and neonatal RBC populations. In comparison with previously reported microfluidic devices for single RBC biophysical measurement, this system has a higher throughput, higher signal to noise ratio, and the capability of performing multi-parameter measurements.     

Phorbol Esters from Jatropha Meal Triggered Apoptosis, Activated PKC-δ, Caspase-3 Proteins and Down-Regulated the Proto-Oncogenes in MCF-7 and HeLa Cancer Cell Lines

Jatropha meal produced from the kernel of Jatropha curcas Linn. grown in Malaysia contains phorbol esters (PEs). The potential benefits of PEs present in the meal as anticancer agent are still not well understood. Hence, this study was conducted to evaluate the cytotoxic effects and mode of actions of PEs isolated from Jatropha meal against breast (MCF-7) and cervical (HeLa) cancer cell lines. Isolated PEs inhibited cells proliferation in a dose-dependent manner of both MCF-7 and HeLa cell lines with the IC₅₀ of 128.6 ± 2.51 and 133.0 ± 1.96 μg PMA equivalents/mL respectively, while the values for the phorbol 12-myristate 13-acetate (PMA) as positive control were 114.7 ± 1.73 and 119.6 ± 3.73 μg/mL, respectively. Microscopic examination showed significant morphological changes that resemble apoptosis in both cell lines when treated with PEs and PMA at IC₅₀ concentration after 24 h. Flow cytometry analysis and DNA fragmentation results confirmed the apoptosis induction of PEs and PMA in both cell lines. The PEs isolated from Jatropha meal activated the PKC-δ and down-regulated the proto-oncogenes (c-Myc, c-Fos and c-Jun). These changes probably led to the activation of Caspase-3 protein and apoptosis cell death occurred in MCF-7 and HeLa cell lines upon 24 h treatment with PEs and PMA. Phorbol esters of Jatropha meal were found to be promising as an alternative to replace the chemotherapeutic drugs for cancer therapy.     

Phenolics and flavonoids compounds, phenylanine ammonia lyase and antioxidant activity responses to elevated CO₂ in Labisia pumila (Myrisinaceae)

A split plot 3 × 3 experiment was designed to examine the impact of three concentrations of CO? (400, 800 and 1,200 μmol·mol?1) on the phenolic and flavonoid compound profiles, phenylalanine ammonia lyase (PAL) and antioxidant activity in three varieties of Labisia pumila Benth. (var. alata, pumila and lanceolata) after 15 weeks of exposure. HPLC analysis revealed a strong influence of increased CO? concentration on the modification of phenolic and flavonoid profiles, whose intensity depended on the interaction between CO? levels and L. pumila varieties. Gallic acid and quercetin were the most abundant phenolics and flavonoids commonly present in all the varieties. With elevated CO? (1,200 μmol·mol?1) exposure, gallic acid increased tremendously, especially in var. alata and pumila (101-111%), whilst a large quercetin increase was noted in var. lanceolata (260%), followed closely by alata (201%). Kaempferol, although detected under ambient CO? conditions, was undetected in all varieties after exposure. Instead, caffeic acid was enhanced tremendously in var. alata (338~1,100%) and pumila (298~433%). Meanwhile, pyragallol and rutin were only seen in var. alata (810 μg·g?1 DW) and pumila (25 μg·g?1 DW), respectively, under ambient conditions; but the former compound went undetected in all varieties while rutin continued to increase by 262% after CO? enrichment. Interestingly, naringenin that was present in all varieties under ambient conditions went undetected under enrichment, except for var. pumila where it was enhanced by 1,100%. PAL activity, DPPH and FRAP also increased with increasing CO? levels implying the possible improvement of health-promoting quality of Malaysian L. pumila under high CO? enrichment conditions.     

Numerical investigation of turbulent free jet flows issuing from rectangular nozzles: the influence of small aspect ratio

In this research, the fluid and thermal characteristics of a rectangular turbulent jet flow is studied numerically. The results of three-dimensional jet issued from a rectangular nozzle are presented. A numerical method employing control volume approach with collocated grid arrangement was employed. Velocity and pressure fields are coupled with SIMPLEC algorithm. The turbulent stresses are approximated using k–e{\varepsilon} model with two different inlet conditions. The velocity and temperature fields are presented and the rates of their decay at the jet centerline are noted. The velocity vectors of the main flow and the secondary flow are illustrated. Also, effect of aspect ratio on mixing in rectangular cross-section jets is considered. The aspect ratios that were considered for this work were 1:1 to 1:4. The results showed that the jet entrains more with smaller AR. Special attention has been drawn to the influence of the Reynolds number (based on hydraulic diameter) as well as the inflow conditions on the evolution of the rectangular jet. An influence on the jet evolution is found for smaller Re, but the jet is close to a converged state for higher Reynolds numbers. The inflow conditions have considerable influence on the jet characteristics.     

Newtonian and Shear-thinning Taylor flow heat transfer in wavy micro-tubes: a numerical study

Meccanica - In the present study, the two-phase gas–liquid convective heat transfer is numerically studied inside uniformly heated wavy micro-tubes in the Taylor flow regime. Both Newtonian...     

Insulin Resistance Associated Genes and miRNAs

Type 2 diabetes mellitus is the result of resistance to insulin function along with inadequate insulin secretion, leading to a number of dysfunctions characterized by hyperglycemia, and it is associated with microvascular, macrovascular, and neuropathic complications. There is compelling evidence that the decline in both insulin sensitivity and insulin secretion has a genetic component. In addition, increasing evidence suggests that microRNAs (miRNAs) as key regulators of gene expression play significant roles in insulin production, secretion, and function that regulate the function of insulin-target tissues. The current review demonstrates the candidate genes and the related miRNAs involved in molecular pathogenesis of insulin resistance in type 2 diabetes mellitus. In doing so, it provides an opportunity for more focused investigations that may identify the genes and miRNAs with a role in the pathogenesis of type 2 diabetes mellitus and its treatment.