We summarize the advantages and disadvantages of some of the most commonly used bioinks. We have probed the mechanical and cytotoxicity properties of Cellink and designed our own bioink from gelatin and Xanthan gum.

Eggshell Membrane (ESM) is a naturally occurring proteinaceous microfibrous scaffold capable of mimicking the extracellular matrix (ECM). The extraction methodology deployed for its extraction process impedes its extensive application as a biomaterial in regenerative medicine. Herein, a unique route was deployed to decorate the surface of ESM with electrospun polycaprolactone (PCL) nanofiber in order to ameliorate the above problems and also fabricate a novel ECM mimicking bilayered scaffold for skin tissue engineering applications. Microstructural and surface topographic analysis confirms the formation of bilayered structure with smooth electrospun PCL nanofibers decorated on ESM. Carbodiimide chemistry was utilized to crosslink the two layers. Cytocompatibility evaluation of scaffolds was carried out with Human dermal fibroblast (HDF) cells. The biomimetic architecture and protein rich composition of as fabricated bilayered construct facilitated extensive cell adhesion, proliferation and migration in contrast the bare natural tissue led to impeded cell adhesion.

We report a roll-to-roll dry processing for making low cost and high performance electrodes for lithium-ion batteries (LIBs). Currently, the electrodes for LIBs are made with a slurry casting procedure (wet method). The dry electrode fabrication is a three-step process including: step 1 of uniformly mixing electrode materials powders comprising an active material, a carbonaceous conductor and the soft polymer binder; step 2 of forming a free-standing, continuous electrode film by pressing the mixed powders together through the gap between two rolls of a roll-mill; and step 3 of roll-to-roll laminating the electrode film onto a substrate such as a current collector. Compared with the conventional wet slurry electrode manufacturing method, the dry manufactural procedure and infrastructure are simpler, the production cost is lower, and the process eliminates volatile organic compound emission and is more environmentally friendly, and the ability of making thick (>120µm) electrodes with high tap density results in high energy density of final energy storage device. A prototype LIBs of LiNi0.6Mn0.2Co0.2O2 (NMC622)/graphite also has 230 Wh/ kg energy density.

In this study, 3 types of zwitterionic phospholipid biosurfactants LDP(S), CDP(S) and CTDP(S) were prepared from 3 different raw materials such as rapeseed oil, coconut oil and cottonseed oil respectively. The structure of the resulting phospholipid biosurfactants was elucidated by FT-IR, 1H NMR and 13C NMR spectroscopies and their interfacial properties have been examined such as CMC, static surface tension, wetting property, solution stability, and foam property. Interfacial property measurement and prescription test in cosmetic formulation prepared with the newly synthesized biosurfactants revealed that CDP(S) biosurfactant possesses excellent mildness and superior interfacial properties, indicating the potential applicability in cosmetic product formulations.

Coupling semiconductors with electrochemical processes can lead to unusual materials, and attractive, practical device configurations. This work examines the reaction mechanism for single-step electrodeposition approach that creates device quality copper-indium-selenide (CISe) films with either polycrystalline or nanocrystalline morphologies on Cu and steel foils, respectively. The polycrystalline CISe film grows from In3+/Se4+ solution on Cu foil as Cu→ CuxSe→ CuInSe2; it may be used in standard planar pn devices. The nanocrystalline CISe film grown from Cu+/In3+/Se4+ solution follows the CuSe(In)→ CuInSe2→ CuIn3Se5 sequence. The latter approach leads to naturally ordered, space-filling nanocrystals, comprising interconnected 3-dimensional network of sharp, abrupt, p-CISe/n-CISe bulk homojunctions with extraordinary electro-optical attributes. Sandwiching these films between band-aligned contact electrodes can lead to high performance third generation devices for solar cells, light emitting diodes or photoelectrodes for fuel cells. Both approaches produce self-stabilized CISe absorbers that avoid recrystallization steps and can be roll-to-roll processed in simple flexible thin-film form factor for easy scale-up.

In recent years, modified graphene has been used in various biomedical applications due to its excellent properties that allow the development of devices capable of detecting macromolecules within the human organism, also for biomolecular analysis, discovery of biomarkers, bioimaging and target delivery. These applications involve interactions between enzymes, proteins, peptides, DNA, RNA, etc. and modified graphene, therefore the study and the theoretical and experimental investigation of these interactions is essential for the development of nanobio-technology. For example, many applications based on using modified graphene to detect macromolecules require studying the changes in the properties of doped graphene when interacting with macromolecules. In this work, DFT and molecular dynamics methods were used to obtain results of the changes in energy density of states of graphene doped with iron when it is made to interact with coenzyme A. Besides, we presented a study of molecular dynamics in order to determine the quantum factors that guide the interaction graphene-coenzyme A. The system was studied in aqueous medium which it was simulated by the dielectric constant of water. The results confirm that the methodology presented in this work can be used to theoretically detect various macromolecules.

In the present world scenario the demand for fresh water and clean energy is driving the need to convert a microbial fuel cell (MFC) into an algal-based microbial desalination cell (MDC) that can support algal growth along with desalination of saline water. In this study, the performance of a five-chambered MDC fed with saline water having two different salt concentrations, namely 2.5 g/L and 5.0 g/L in desalination chamber, as well as MDC operated without algae in catholyte was investigated. The algal-based MDC operated with 5 g/L of total dissolved solid (TDS) in desalination chamber exhibited the best performance results among all other combinations giving a maximum power density of 45.52 mW/m2 and a desalination efficiency of 71 ± 2 %. Also, a chemical oxygen demand (COD) removal efficiency of 78 % and coulombic efficiency of 12.24 % was achieved with 5 g/L NaCl concentration in desalination chamber. Based on this experimental performance evaluation, it can be inferred that algal-based MDC can provide a promising and sustainable approach for wastewater treatment with the capability of simultaneous desalination, algal production and electrical energy recovery.

Energy-efficient condensation of steam contained in atmospheric air has emerged as a solution to the water scarcity. Academic and industrial research works that seeks to develop water collection devices with high efficiency has great relevance for the scientific community. In this work, we aim to show that modified carbon nanotubes forest can remove the condensed drops easier than a hydrophobic and a super-hydrophilic surface. In addition, this result was reached at high super saturation level which is an innovative aspect of this work. The Vertically Aligned Carbon Nanotubes (VACNTs) were grown on steel pipes. We used a CO2 laser and an O2 plasma to perform the post treatments that changed the CNTs to super-hydrophobic and super-hydrophilic, respectively. In addition, the CO2 laser treatment added a second level of roughness in the surface by etching the nanotubes walls. A polyethylene coating attached the carbon nanotubes to the substrate. We experimentally demonstrated a 24% higher vapor condensation rate at high supersaturations levels.

Supercapacitors have the potential to complement or replace batteries in many current and emerging applications. As inexpensive and environmentally benign capacitive materials, manganese oxides are promising electrode materials. Nanostructured oxides have high energy storage capacities owing to their increased surface-area-to-volume ratios as compared to bulk materials. By electrospinning precursor-containing polymer fibers and subsequently calcining, nanostructured MnOx fibers can be prepared with relative ease. Controlling calcination pressure and time provides a route for variable capacitance via modifying surface roughness and oxide phase. At moderate pressures and short calcination times, mixed-phase Mn2O3/Mn3O4 fibers with high surface roughness exhibit enhanced electrochemical specific capacitance.

As a pure element, bismuth is a semimetal which possesses several interesting physical properties, not all of them well understood. The recent discovery of superconductivity, as predicted by our group, and the increasing superconducting transition temperature as the pressure applied increases, are some examples of its particularities. Also, the fact that the amorphous phase is superconductive with a transition temperature several orders of magnitude larger than the crystalline at ambient pressure is unusual. These phenomena have also motivated our predictions for the transition temperatures of Bi-bilayers and the Bi-IV phase. When mixed with other elements, bismuth seems to contribute to the superconducting character of the resulting material. Here we study the binary copper-bismuth amorphous system which is known to superconduct in diverse compositions. Using ab initio molecular dynamics and the undermelt-quench method, we generate an amorphous structure for a 144-atom supercell corresponding to the Cu61Bi39 system. We calculate the electronic and vibrational densities of states for the amorphous system and estimate a superconducting critical temperature of 4.2 K for the amorphous state.

We have recently developed a novel semiconductor, (ZnO)x(InN)1-x (abbreviated to ZION). In this study, we have succeeded in direct epitaxial growth of ZION films on 19–21%-lattice-mismatched c-plane sapphire by radio-frequency (RF) magnetron sputtering. X-ray diffraction analysis showed that there is no epitaxial relationship between ZION films fabricated at room-temperature (RT) and the sapphire substrates, while the films fabricated at 450oC grow epitaxially on the sapphire substrates. From the analysis of time evolution of the surface morphology, the process for the epitaxial growth of ZION on sapphire is found to consist of three stages. They are (i) initial nucleation of ZION crystallites with crystal axis aligned to the sapphire substrate, (ii) island growth from the initially formed nuclei and subsequent nucleation (secondary nucleation) of ZION crystallites, and (iii) lateral growth of ZION islands originated from initially formed nuclei. On the other hand, non-epitaxial ZION films fabricated at RT just grow in 3D mode. From these results, we conclude that the substrate temperature is the key to control of nucleation and subsequent epitaxial growth of ZION films on the lattice-mismatched substrate.

By using systematic first-principles calculation, we found that AlTlO3 compound of LiNbO3 structure shows large piezoelectric constants e33 of 10.7 C/m2 and d33 of 56.7 pC/N. These piezoelectric constants are approximately six times larger than those of LiNbO3. AlTlO3 is predicted to be stabilized above 7 GPa. On the other hand, the calculated dielectric constant ε33 shows diverged behavior around 2 GPa. This result indicates that AlTlO3 can be quenchable. Decomposition of the predicted piezoelectric constant revealed that the large piezoelectricity of AlTlO3 originates from the Tl displacement in accordance with external perturbation, which drives the ferroelectric soft mode of the corresponding paraelectric phase. However, the energy difference between the ferroelectric and paraelectric phases was small, approximately 1 meV/f.u. These insights suggest that fluctuation between ferroelectric and paraelectric phases causes large piezoelectricity in AlTlO3.

We report on the time-resolved measurements of photocarrier dynamics in InGaAs/InAlAs superlattices with epitaxial stresses in a wide range of optical pump fluences. We demonstrated that the contribution of free carrier absorption and two-photon absorption to the carrier dynamics decreases with an increase of epitaxial stresses. The lowest relaxation times of 1.7 and 8.3 ps, respectively attributed to carrier trapping and carrier recombination, were obtained for the structure with maximum epitaxial stresses.

Large lattice and thermal expansion coefficients mismatches between III-Nitride (III N) epitaxial layers and their substrates inevitably generate defects on the interfaces. Such defects as dislocations affect the reliability, life time, and performance of photovoltaic (PV) devices. High dislocation densities in epitaxial layer generate higher v-shaped pits densities on the layer top surface that also directly affect the device performance. Therefore, using an approach such as the embedded void approach (EVA) for defects reduction in the epitaxial layers is essential. EVA relies on the generation of high densities of embedded microvoids (∼108/cm2), with ellipsoidal shapes. These tremendous number of microvoids are etched near the interface between the III N thin-film and its substrate where the dislocation densities present with higher values.

This article used a 3-D constitutive model that accounts the crystal plasticity formulas and specialized finite element (FE) formulas to model the EVA in multi-junction PV and therefore to study the effect of the embedded void approach on the defects reduction. Mesh convergence and 2-D analytical solution validation is conducted with accounting thermal stresses. Several aspect and volume ratios of the embedded microvoids are used to optimize the microvoid dimensions.

TiO2 has been widely studied as a photocatalytic material due to its non-toxicity, chemical inertness, and high photocatalytic activity. Here, we explore the operational behavior of a novel TiO2 micropillars array being developed to use solar radiation to treat recycled wastewater in long-duration space missions. A Light Capture model was developed to model light absorption. The Lattice Boltzmann method was used to simulate water flow, and the finite element method was used to model waste mass transfer.

Equimolar mixtures of graphene and iron oxide nanoparticles were subjected to mechanochemical activation. The phase sequence was investigated using Mӧssbauer spectroscopy as function of ball milling time. For low milling times (2-4 hours) the series with hematite (Fe2O3) nanoparticles was fitted with 2 sextets, corresponding to hematite with carbon introduced in the lattice. At high milling times (8-12 hours) the same series exhibited an additional sextet with hyperfine parameters characteristic to iron carbides and a quadrupole-split doublet, which could be assigned to carbon clusters with small amounts of iron in them. The series with magnetite nanoparticles (Fe3O4) at low milling times was analyzed considering 2 sextets, corresponding to the tetrahedral and octahedral sites of magnetite. At high milling times, the magnetite series also exhibited a broad sextet representing iron carbides and the doublet associated with iron-containing carbon clusters. Supporting information was obtained by determinations of the recoilless fraction. The results were compared with those obtained by ball milling graphite with hematite and magnetite nanoparticles.

Pseudo-α or near-α titanium alloys are being widely used in the power generation industry due to their stability at high temperature service, good mechanical characteristics and corrosion resistance. Particularly Ti-6% Al-1.5% V-1.0Mo-0.5% Zr-0.1% C alloy is mainly used in turbines components, heat exchangers and pipes for steam conduction, among others; these are subjected to critical conditions of temperature, abrasion and corrosive environments. A good performance of such devices depends on the chemistry and of the material processing story.

Effects on microstructure and wear resistance with the addition of Ru and small variation of V and Mo amounts in the Ti-6% Al-1.5% V-1.0Mo-0.5% Zr-0.1% C alloy were analyzed. Three different alloys were melted in a vacuum induction furnace with a cooled copper skull under an argon protective atmosphere for this study

Four alloys were melted “Alloy 1” Ti-6% Al-1.5% V-1.0Mo-0.5% Zr-0.1% C-0.3% Ru, “Alloy 2” Ti-6%Al-0.5%V-1.6%Mo-0.5%Zr-0.1% C-0.3% Ru, “Alloy 3” Ti-6%Al-2.2%V-0.5%Mo-0.5%Zr-0.1%C-0.3%Ru. After melting, all alloys were homogenized at 1200°C for two hours, followed by hot rolling above β transition temperature with a reduction of 50% in thickness.

All alloys were analyzed by using scanning electron microscopy (SEM) and Vickers Micro hardness (HV). Results shown that Mo and V variations modified the micro hardness by microstructure refinement. In contrast, the addition of Ru showed no microstructure modification.

CVD graphene growth typically uses commercially available cold-rolled copper foils, which includes a rich topography with scratches, dents, pits, and peaks. The graphene grown on this topography, even after annealing the foil, tends to include and reflect these topographic features. Further, the transfer of such CVD graphene to a flat substrate using a polymer transfer method also introduces wrinkles. Here, we examine an electropolishing technique for reducing native foil defects, characterize the resulting foil surface, grow single-crystal graphene on the polished foil, and examine the quality of the graphene for such defects.

Formation of a low barrier back contact plays a critical role in improving the photoconversion efficiency of the CdTe solar cells. Incorporating a buffer layer to minimize the band bending at the back of the CdTe device can significantly lower the barrier for the hole current, improving open circuit voltage (VOC) and the fill factor. Over the past years, researchers have incorporated the both ZnTe and Te as buffer layers to improve CdTe device performance. Here we compare device performance using these two materials as buffer layers at the back of CdTe devices. We show that using Te in contact to CdTe results in higher performance than using ZnTe in contact to the CdTe. Low temperature current density-voltage measurements show that Te results is a lower barrier with CdTe than ZnTe, indicating that Te has better band alignment, resulting in less downward bending in the CdTe at the back interface, than ZnTe does.

Geopolymeric mortars with volumetric fractions of 0.6:1:0.3 for a binder powder, fine sand and sodium hydroxide solution (12M), respectively; have been fabricated by mixing the solid materials and the subsequent addition of sodium hydroxide solution 12M to form a workable paste, to later be cured for 28 days at room temperature. The microstructures of the fabricated materials reveal the existence of two phases with notable difference, one continuous to the geopolymer binder phase and another discontinuous of fine sand particles agglutinated by the binder phase. Mechanical compression tests are performed at a constant compression rate of 0.05 mm/min and at temperatures ranged from room temperature to 500°C. The mechanical results are ranged from 19 and 69 MPa for all the materials studied. On the other hand, there was an increase in mechanical resistance up to test temperatures of 200°C and the progressive reduction of resistance at temperatures above 200°C, with a fragile-ductile transition zone between 400 and 500°C and completely ductile behavior from test temperatures of 500°C.