Dynamic stability of short cantilever columns subjected to distributed axial loads

Dynamic stability of short cantilever columns subjected to two types of distributed loads are investigated by using a finite element formulation. Buckling load parameters and frequency parameters bounding the instability regions are presented for various slenderness ratios.     

Magnetite/CdTe magnetic-fluorescent composite nanosystem for magnetic separation and bio-imaging

A new synthesis protocol is described to obtain a CdTe decorated magnetite bifunctional nanosystem via dodecylamine (DDA) as cross linker. High resolution transmission electron microscopy (HRTEM), energy-dispersive x-ray spectroscopy (EDAX), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and fluorescence microscopy are used to characterize the constitution, size, composition and physical properties of these superparamagnetic-fluorescent nanoparticles. These CdTe decorated magnetite nanoparticles were then functionalized with anti-epidermal growth factor receptor (EGFR) antibody to specifically target cells expressing this receptor. The EGFR is a transmembrane glycoprotein and is expressed on tumor cells from different tissue origins including human leukemic cell line Molt-4 cells. The magnetite-CdTe composite nanosystem is shown to perform excellently for specific selection, magnetic separation and fluorescent detection of EGFR positive Molt-4 cells from a mixed population. Flow cytometry and confocal laser scanning microscopy results show that this composite nanosystem has great potential in antibody functionalized magnetic separation and imaging of cells using cell surface receptor antibody.     

Experimental investigation of thermal resistance of a heat sink with hexagonal fins

In the present work, the effects of the heights, widths of the hexagonal fins, streamwise and spanwise distances between fins and flow velocity on thermal resistance and pressure drop characteristics were investigated using Taguchi experimental design method. Also the temperature distribution within the selected pin fins was determined. Thermal resistance and dimensionless pressure drop were considered as performance statistics. L₁₈(2¹*3⁷) orthogonal array was selected as an experimental plan for the five parameters mentioned above. While the optimum parameters were determined, due to the goals (above aims) more than one being, the trade-off among goals was considered. First of all, each goal was optimized, separately. Then, all the goals were optimized together, considering the priority of the goals, and the optimum results were found to be fin width of 14 mm, fin height of 150 mm, spanwise distance between fins of 20 mm, streamwise distance between fins of 10 mm and flow velocity of 4 m/s.     

Optimising dopants and properties in BiMeO3 (Me = Al,Ga, Sc,Y, Mg2/3Nb1/3, Zn2/3Nb1/3, Zn1/2Ti1/2) lead-free BaTiO3-BiFeO3 based ceramics for actuator applications

A crystallochemical framework is proposed based on electronegativity difference (e_n) and tolerance factor (t) to optimise the BiMeO₃ dopants and therefore the piezoelectric and high-field strain response in BaTiO₃-BiFeO₃ based ceramics. Compositions in the series 0.05Bi(Me)O₃-0.25BaTiO₃-0.7BiFeO₃ (BMe-BT-BF, Me: Y, Sc_1/2Y_1/2, Mg_2/3Nb_1/3, Sc, Zn_2/3Nb_1/3, Zn_1/2Ti_1/2, Ga, and Al) were fabricated using solid state synthesis and furnace cooled. Scanning electron microscopy and X-ray diffraction revealed that only Bi(Mg_2/3Nb_1/3)O₃ and BiScO₃ dopants, which lie in a narrow range of e_n vs. t, form homogeneous ceramics, free from secondary phases reflected in their superior piezoelectric coefficients (d₃₃ ～145 pC/N). All other BiMeO₃ additions exhibited either secondary phases (Y) and/or promoted a two-phase perovskite matrix (Zn, Ga and Al). The promising initial properties of BiScO₃ doped compositions prompted further studies on 0.05BiScO₃-(0.95-x)BaTiO₃-(x)BiFeO₃ (BS-BT-BF, x?=?0.55, 0.60, 0.625, 0.65, and 0.70) ceramics. As x increased the structure changed from predominantly pseudocubic to rhombohedral, resulting in a transition from a relaxor-like to ferroelectric response. The largest d₃₃^* (465?pm/V) was achieved for x?=?0.625 under 5?kV/mm at the crossover from relaxor to ferroelectric behaviour. BS-BT-BF with x?=?0.625 showed >0.3% strain under 6?kV/mm up to 175?°C, demonstrating its potential for actuator applications.     

Treatment of a mixture of three pesticides by photo- and electro-Fenton processes

In the present work, a comparative study of a mixture of three pesticides (chlortoluron, carbofuran and bentazon) has been investigated by advanced oxidation processes such as photo-Fenton and electro-Fenton. These processes are based on the in situ production of hydroxyl radical, a highly strong oxidant, which allows the degradation of organic pollutants until their mineralization into CO₂ and H₂O. For the photo-Fenton process, the effect of key parameters such as initial catalyst (Fe³⁺) concentration and hydrogen peroxide (H₂O₂) dosage were studied. Under optimal operating conditions, the evolution of total organic carbon (TOC) has been investigated for the two processes. Obtained results showed that more than 90% of TOC removal was obtained after only 2 h of photo-Fenton treatment whereas the electro-Fenton process needed 8 h of treatment. Nevertheless, the comparison of cost treatment shows that the photo-Fenton process is more expensive than electro-Fenton. The evolution of pesticide's concentration during treatment was determined by high performance liquid chromatography (HPLC). Inorganic ions released such as chloride, nitrate, sulphate and ammonium ions are identified and their kinetic evolution was measured by ion chromatographic analyses.     

Accelerated Polyethylene Terephthalate (PET) Enzymatic Degradation by Room Temperature Alkali Pre-treatment for Reduced Polymer Crystallinity

Polyethylene terephthalate (PET) is the most widely employed plastic for single-use applications. The use of enzymes isolated from microorganisms, such as PETase with the capacity to hydrolyze PET into its monomers, represents a promising method for its sustainable recycling. However, the accessibility of the enzyme to the hydrolysable bonds is an important challenge that needs to be addressed for effective biodegradation of postconsumer PET. Here, we combined an alkali pre-treatment (25 °C) with PETase incubation (30 °C) with post-consumed PET bottles. The pre-treatment modifies the surface of the plastic and decreases its crystallinity enabling the access of the enzyme to the hydrolysable chemical bonds. When the alkali pre-treatment is incorporated into the enzymatic process the degradation yields increase more than one order of magnitude reaching values comparable to those obtained during heating/cooling cycles. Our results show energetic advantages over other reported pre-treatments and open new avenues for sustainable PET recycling.     

Effect of soil moisture stress from flowering to grain maturity on functional properties of Sri Lankan rice flour

Functional properties of flour from rice variety BG 250 (short‐season) and BG 359 (long‐season) exposed to soil water stress from flowering to grain maturity were investigated. Protein content was reduced in both varieties but lipid was reduced only in BG 359 in response to soil moisture stress. AAM content decreased in BG 250 but unaffected in BG 359. Water stress increased swelling power, onset of pasting, peak viscosity, granular breakdown, gel hardness, and cohesiveness in both varieties. Gelatinization temperatures in both varieties were unaffected by water stress, while gelatinization enthalpy was increased in BG 359 but unchanged in BG 250. A double endotherm (type I and type II) appeared in AM–lipid complex in all the flour samples. Type I AM–lipid complex was reduced in BG 359 in response to water stress. Only a single endotherm appeared in the re‐formed AM–lipid complex in gelatinized starch. The magnitude of the ΔH of re‐formed AM–lipid complex was reduced in BG 359 in response to soil moisture stress, but unaffected in BG 250. Water stress decreased AP retrogradation in BG 359 while it was unaffected in BG 250.     

Broad-Wavelength Light-Driven High-Speed Hybrid Crystal Actuators Actuated Inside Tissue-Like Phantoms

Research on molecular crystals exhibiting light-driven actuation has made remarkable progress through the development of various molecules and the identification of driving mechanisms. However, crystals developed to date have been driven mainly by ultraviolet (UV) or blue light irradiation, and driving by red or near-infrared (NIR) light has not been attempted yet. Herein, a broad-wavelength light-driven molecular crystals that exhibit high-speed bending by photothermal effect is developed. Titanium carbide (Ti₃C₂T_x) MXene nanosheets are integrated into salicylideneaniline crystals to extend the wavelength range that causes photothermally driven bending to UV, visible, and NIR light. In addition, unlike the thin pristine molecular crystals that show slow photoisomerization-induced bending only under UV light, the MXene layer enables the molecular crystals to be actuated rapidly regardless of their thickness over a wide range of wavelengths. The hybridization of molecular crystals with MXene, which exhibits strong biocompatibility as well as NIR light-driven photothermal effect, allows for the bending of the hybrid crystals inside agar phantoms mimicking biological tissue. Last, it is confirmed that MXene hybridization can be extended to common molecular crystals including various salicylideneaniline and anisole derivatives.