Ensemble of surrogates

The custom in surrogate-based modeling of complex engineering problems is to fit one or more surrogate models and select the one surrogate model that performs best. In this paper, we extend the utility of an ensemble of surrogates to (1) identify regions of possible high errors at locations where predictions of surrogates widely differ, and (2) provide a more robust approximation approach. We explore the possibility of using the best surrogate or a weighted average surrogate model instead of individual surrogate models. The weights associated with each surrogate model are determined based on the errors in surrogates. We demonstrate the advantages of an ensemble of surrogates using analytical problems and one engineering problem. We show that for a single problem the choice of test surrogate can depend on the design of experiments.     

Eosin-G and ethyl eosin dye sensitized CdS nanowires towards dye sensitized solar cells applications

One dimensional (1-D) CdS nanowires have been grown through a low temperature chemical route and have been sensitized with eosin-G and ethyl eosin dyes to broaden the absorption spectrum of CdS and to enhance the photoelectrochemical (PEC) performance under illumination. The used method is advantageous due to its simplicity, low cost, scalability, and controllability. Interestingly, eosin-G and ethyl eosin dyes yield nearly four- and six-fold increase in device efficiency compared to bare CdS when tested in dye-sensitized solar cell assembly. Structural, surface morphological, optical, and surface wettability studies have been formulated for CdS, whereas identification of materials along with PEC investigations were conducted through current density–voltage (J-V), external quantum efficiency (EQE), characteristics under the illumination of 94.6 mW/cm² (AM 1.5G), and electrochemical impedance spectroscopy (EIS).     

Active cellular preform derived from stems of jute and sticks of cane and their suitability for bulk porous Si/SiC ceramics

Stems of Jute (Corchorus capsularis L.) and sticks of Cane (Calamus rotang L.), plants of immense economic importance in the Indian subcontinent, were converted into carbonaceous perform (C-preform) maintaining the circular cylindrical shapes in lengths of 0.02–0.05 m by controlled thermal processing. Plant material precursors were characterized by analysis of elemental (C, H, N) and molecular (cellulose, hemicellulose, lignin) compositions, by determination of Bulk Density (BD) and ash content and by optical microscopy and X-ray diffractometry (XRD). C-preforms were also characterized by measurement of BD and by Scanning Electron Microscopy (SEM) and XRD. The C-preforms were further subjected to infiltration with Si-melt (1823–1923 K) under vacuum. Spontaneous infiltration and reaction yielded composite ceramics preserving the morphology of native Jute Stem (JS) and Cane Stick (CS) precursors on macro and micro scale. The materials were found to be duplex composites with Si and β-SiC as crystalline phases. The end ceramics were characterized by measurement of BD, and also by SEM and by XRD. Measured mean BD of the Si/SiC composites derived from JS and CS were 2190 Kg m⁻³ and 2250 Kg m⁻³. The respective volume fractions of large diameter (>100 μm) bulk pores were 0.134 and 0.204, in the composites derived from JS and CS. Taking into account the measured volume fraction internal pores of 0.11 and 0.149, the volume fractions of SiC were calculated to be 0.136 and 0.307 in the composites derived from JS and CS respectively, closely tallying with those calculated from the C-preform bulk densities. The cellular Si/SiC ceramics derived from JS and CS having special morphologies with long and large porous channels and oriented growth of constituent phases are likely to be suitable for devices such as high temperature insulators, catalyst support structures for gas phase reactions at elevated temperatures, molten metal filters and others.     

Sol–gel approach to near-net-shape oxide–oxide composites reinforced with short alumina fibres—The effect of crystallization

Near-net-shape (NNS) high alumina (alumina:silica = 96:4, in equivalent weight ratio) fibre reinforced ceramic matrix composites (CMCs) were prepared with single and bicomponent sols following sol–gel vacuum infiltration technique. The CMCs were characterized by X-ray diffraction (XRD), three-point bend test and scanning electron microscopy (SEM). Crystallization of tetragonal zirconia (t-ZrO₂) in the composite, CZY having zirconia–yttria matrix and that of gamma alumina (γ-Al₂O₃) in the composites, CAZ having alumina–zirconia matrix, CAS having alumina–silica matrix and CA having alumina matrix, enhanced the flexural strength values and pseudo-ductile character of CMCs.     

Synthesis and Structures of Two Triorganotin(IV) Polymers R3Sn{O2CC6H4[N=C(H)}{C(CH3)CH(CH3)-3-OH]-p} n (R = Me and Ph) Containing a 4-[(2Z)-(3-Hydroxy-1-methyl-2-butenylidene)amino] benzoic Acid Framework

Two new polymeric triorganotin(IV) complexes R₃Sn{O₂CC₆H₄[N=C(H)}{C(CH₃)CH(CH₃)-3-OH]-p} _n ([Me₃Sn(LH)] _n : 1) and ([Ph₃Sn(LH)] _n : 2) containing a 4-[(2Z)-(3-hydroxy-1-methyl-2-butenylidene)amino]benzoate (LH) framework were prepared. Both compounds have been characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, IR and ¹¹⁹Sn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of complexes 1 and 2 reveal that they exist as polymeric zig-zag chains in which the LH-bridged Sn-atoms adopt a trans-R₃SnO₂ trigonal bipyramidal configuration with R groups in the equatorial positions and the axial sites occupied by an oxygen atom from the carboxylate ligand and the alcoholic oxygen atom of the next carboxylate ligand in the chain. The carboxylate ligands coordinate in the zwitterionic form with the alcoholic proton moved to the nearby nitrogen atom.     

Moldless Printing of Silicone Lenses with Embedded Nanostructured Optical Filters

In this work, both light‐shaping and image magnification features are integrated into a single lens element using a moldless procedure that takes advantage of the physical and optical properties of mesoporous silicon (PSi) photonic crystal nanostructures. Casting of a liquid poly(dimethylsiloxane) pre‐polymer solution onto a PSi film generates a droplet with a contact angle that is readily controlled by the silicon nanostructure, and adhesion of the cured polymer to the PSi photonic crystal allows preparation of lightweight (10 mg) freestanding lenses (4.7 mm focal length) with an embedded optical component (e.g., optical rugate filter, resonant cavity, and distributed Bragg reflector). The fabrication process shows excellent reliability (yield 95%) and low cost and the lens is expected to have implications in a wide range of applications. As a proof‐of‐concept, using a single monolithic lens/filter element it is demonstrated: fluorescence imaging of isolated human cancer cells with rejection of the blue excitation light, through a lens that is self‐adhered to a commercial smartphone; shaping of the emission spectrum of a white light emitting diode to tune the color from red through blue; and selection of a narrow wavelength band (bandwidth 5 nm) from a fluorescent molecular probe.     

Principles of treating enlarging pseudoaneurysm in a dialysis arteriovenous graft

The arteriovenous graft (AVG) is one of the major types of permanent vascular access used to provide hemodialysis. Complications encountered with AVG use include stenosis, infection, thrombosis, and pseudoaneurysm formation. Venous outflow stenosis along with frequent needle cannulation at the same site can lead to breakdown of the graft material, resulting in pseudoaneurysm formation. In the following case, we illustrate common management principles used to treat pseudoaneurysms. While stent‐grafts have been utilized for pseudoaneurysm repair, stent‐graft usage is not always optimal. Surgical management may be an ideal choice of treatment. The role of educating the dialysis staff and patients is essential to identify and minimize the risk of pseudoaneurysm formation.     

Photo-electrocatalytic methanol oxidation on Pd decorated BiOI nanoparticles in alkali

Journal of Materials Science - Palladium–bismuth oxoiodide nanocomposites of various molar ratios of Pd and BiOI have been synthesized by the facile solvothermal method following the chemical...     

Fabrication of Polyimide-Modified UHMWPE Composites and Enhancement Effect on Tribological Properties

Polyimide-modified ultrahigh molecular weight polyethylene (UHMWPE) composites were fabricated by hot-press molding process. Mesoscopic morphologies of polyimide/UHMWPE blending systems show high compatibility between the phases of polyimide and UHMWPE when the weight ratio of polyimide is no more than 50?wt%. Investigation of the tribological properties with a reciprocating ball-on-flat contact tribometer shows that the polyimide filler has important effects on the friction and wear behavior of UHMWPE composites. Compared to pure UHMWPE, the composite with 50?wt% polyimide improved tribological properties best and exhibited 43.1% reduction in friction coefficient and 66.7% reduction in wear volume loss.     

Labelling Proteins with Carbon Nanodots

We present efficient labelling of several proteins with orange‐emissive carbon dots. N‐Hydroxysuccinimide was used to activate the carboxyl groups of carbon dots, which subsequently reacted with the lysine groups present on the protein. Labelling was confirmed by UV absorption spectroscopy, PAGE and fluorescence correlation spectroscopy. Protein‐conjugated carbon dots showed an enhancement in fluorescence lifetime and intensity owing to reduced intramolecular dynamic fluctuations. Single‐molecule fluorescence measurements showed reduced fluorescence fluctuations and higher photon budget after protein tagging. Our study opens up opportunities to use carbon dots as highly precise biolabelling probes.