Emissive PbS/CdS core/shell nanosheets are synthesized using a cation-exchange method. A significant blue-shift of the photoluminescence is observed, indicating a stronger quantum confinement in the PbS core as its thickness is reduced to eight atomic layers. High resolution transmission-electron-microscopy images of the cross-sections of the core/shell nanosheets show atomically sharp interfaces between PbS and CdS. Accurate analysis of the thickness of each layer reveals the relationship between the energy-gap and the thickness in the extremely one-dimensionally confined nanostructure.

Natural cane reeds (Latin name Arundo Donax L and here termed ADL) have been used on woodwind instruments for centuries with little change. The reed acts as a mechanical valve controlling the energy input into the musical instrument and it is the musician’s first option for altering the instrument’s sound and response characteristics. Despite this, their consistency, variable performance, durability and sensitivity to ambient conditions make it difficult for the musician to find and maintain a reed that responds to their liking. Thus it is desirable to examine the material, microstructural and anatomical properties of the reed and their contributions to vibrational performance with input from mechanical engineers, materials scientists and musicians.

The current study is part of an on-going research project, and this paper presents preliminary results. In the present work raw samples of ADL obtained from a manufacturer in pre-cut form are sectioned into longitudinal and transverse specimens for mechanical characterization. Prior to testing, samples are conditioned using an incubation system to 37 degrees Celsius and 90% relative humidity, mimicking in-use conditions of the reed. Initial microstructure analysis of each specimen is completed using optical microscopy to quantify fiber spatial arrangement, size and the existence of micro-cracks along the fiber-matrix interface. X-ray diffraction is also used to quantify the fraction of crystalline cellulose present in each sample. Specimens are then excited over a specific frequency range similar to that of in-use reeds using pressure waves in a non-contact setup. Values of internal friction are obtained as logarithmic decrement values for frequency-dependent decay. One set of specimens is then subjected to cyclic mechanical loading at low frequency (< 1Hz) and stresses up to 15MPa. The other set is maintained at the given environmental conditions using the incubator and aged through temperature and humidity cycling. Comparisons of post-testing microstructure damage and internal friction measurements are then completed to delineate specific degradation mechanisms due to mechanical/fatigue deterioration and moisture cycling. Internal friction is found to be dependent on both frequency, moisture and cyclic loading. Furthermore, the existence of microstructural cracks contributes to increasing decrement values at high frequencies in both fatigued and moisture cycled samples. Statistically significant correlations are discovered between logarithmic decrement and vascular bundle orientation at 700 Hz and logarithmic decrement and parenchyma cell diameter at 1000 Hz. Reductions in internal friction below 400 Hz indicate a decreasing loss modulus (E’’) with increased moisture cycles, although this trend will be tested against a larger sample set in further work.

In this work, we demonstrate that the phase field crystal (PFC) method can be applied to identify and predict the microstructure evolution during the solidification of the BCC metals in additive manufacturing. The results reveal the columnar structure of the grains, which matches the grain growth observed in real samples produced with the additive manufacturing technique. The effect of ambient temperature, seed-seed distance and seed-seed misorientation on the grain growth has been investigated. In addition, the formation of crystal defects during the process is recorded and the resulted long-range stresses are calculated using the eigenstresses theory.

Highly flexible, durable aerogels with textile feel were developed at Aspen Aerogels Inc. by sol-gel chemistry and supercritical CO2 solvent extraction. These polyisocyanate-based aerogels reinforced with battings showed little to no brittle fracture with repeated flexing. The crosslinker, the isocyanate content and functionality played an important role on properties such as thermal conductivity, durability and flexural modulus at ambient and cryogenic temperatures. The polyisocyanate aerogels crosslinked with polyamine showed thermal conductivities as low as 18 mW/m-K at ambient pressure and those crosslinked with polyol had low flexural modulus at cryogenic temperatures. Applications of these aerogels in aerospace and diving are presented.

AlGaN based multiple quantum wells (MQWs) were grown on 8° vicinal 4H p-SiC substrates by plasma-assisted molecular beam epitaxy. The MQWs were designed to emit near 300 nm using the wurtzite k.p model. The MQW periodicity and strain state were measured with X-ray diffraction. The optical properties were characterized with temperature dependent photoluminescence (PL). The internal quantum efficiency was estimated from the ratio of room temperature to 18K integrated PL intensity. Internal quantum efficiency up to 48% was achieved. These data are encouraging for future vertical and inverted ultraviolet light emitting diodes grown on p-SiC substrates.

The antibacterial properties are useful to restrain inflammatory response caused by bacterial infection after implantation. The composites of hydroxyapatite (HAp) and silver nano-dots, silver oxide or silver phosphate have been investigated; however there are still some disadvantage in sintering; 1) silver nano-dots grow large, and are not homogenously distributed, 2) silver nano-dots melt and remove, and 3) silver phosphate and silver oxide formed exhibit higher solubility than metal silver. In this study, the distribution of silver nano-dots in HAp microparticles sintered was controlled at grain boundary with a modified silver mirror reaction as a novel route. HAp microparticles adsorbed formaldehyde by a vapor deposition method were soaked in an ammoniacal silver nitrate solution and were then sintered. There was a single phase of HAp including metal silver at 6.4 wt% even after sintering. The silver nano-dots were homogeneously distributed inside the microparticles. The release profiles of silver ions in phosphate buffer saline were compared with a reference; the HAp microparticles were soaked into silver nitrate solution and were then sintered. The distribution of silver in the reference was not homogeneous and large silver microparticles were grown outside the particles at 6.3wt%. The elution amount of silver ions from the microparticles at 12 hours was one-eighteenth of that from the reference. These results suggest that the HAp microparticles including silver nano-dots at grain boundary will be suitable for a long-term antibacterial material.

High Level Waste (HLW) glasses are to be stored in deep geologic repositories around the world. Some potential repository geologies have oxidizing groundwaters while some have reducing or anoxic groundwaters. The differences in the oxidizing potential of the groundwater, expressed as groundwater Eh, which has a profound impact on the release of multivalent species such as iron and uranium from the glass. Static leach testing of monolithic glass samples (ASTM C1220) doped with uranium were performed at 90°C in an Ar glovebox under anoxic and oxic conditions. Tests were performed in both deionized water and in simulated basaltic groundwater that was pre-equilibrated at low Eh. Geochemical modeling of the measured Eh-pH conditions from the oxic and anoxic experiments using Geochemist’s Workbench software, suggested that different colloidal species control the release of uranium species under oxic and anoxic conditions.

Due to their aqueous environment and biocompatible polymers, aqueous two-phase systems (ATPS) provide a mild environment for partition of cells. A comprehensive understanding of cell partition in ATPS will facilitate cell separation and fractionation in ATPS for downstream cell-based analytical applications and various cellular and molecular biology studies. We report the effect of molecular weight of phase polymers on partition of cells between two aqueous phases and their interface. We generate three different ATPS by dissolving polyethylene glycol and dextran of different molecular weights in a standard cell culture medium of fixed composition. After suspending cells in each ATPS, we quantify the number of cells partitioned into each segregated phase and the interface between the two phases. Importantly, we use two-phase solutions of an identical interfacial tension from each ATPS to avoid the effect of interfacial tension on cell partition. Our results indicate that decreasing the molecular weight of one of the phase polymers results in distribution of a greater number of cells toward the phase rich in that polymer. Regardless of molecular weight of polymers used, two-phase solutions made with higher concentrations of polymers cause a significant shift toward cell partition to the interface. This study elucidates the role of polymer molecular weight on cell partition in ATPS and offers formulations for rapid and effective cell partition.

Physics forms a core subject on any Materials Science and Engineering programme. In order to engage first year undergraduate students in the formal education environment, motivating the students is fundamental to ensuring their success. This qualitative study focuses on the use of technology to assess a student’s comprehension of fundamental light phenomena. A knowledge of light phenomena is essential in Materials Science, for the characterization of materials, where electromagnetic (EM) radiation is used as an analytical tool. Using visible light, students can easily see what is happening and when they have to capture digital evidence of the phenomena they focus on the event.

Physical Physics a structured guided approach which initially leads the students through the theory and problem solving. It provides the knowledge scaffold the students require to allow them to use their individual creativity to express their understanding. In this case, understanding is captured and assessed by the production of a portfolio of original photographs of Light phenomena taken by the student.

In addition to a traditional lecture exposition, Physical Physics takes an active learning approach with authentic assessment designed for deep learning. Students learn about relevant light phenomena in the familiar landscape of their world. The assessment provides opportunities for choice, creativity and reflection. It fosters students’ interest to encourage intrinsic motivation and engagement.

This approach has been successfully piloted with first year undergraduate students. Samples of the students’ work is shown. The students interviewed reveal how this approach enhanced their understanding of these Light concepts and changed their perceptions of studying Physics in general.

The study of the chemical stability of solar selective coatings (SSC) for concentrated solar power (CSP) becomes essential for their use at high temperatures. In this paper, the short range order around Mo in Mo-Si3N4 cermets is studied for the first time by X-ray absorption spectroscopy. The information obtained by extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopies gives new insights of the origin of the optical behavior of the cermets cermets after vacuum and air annealing treatments. The established optical and structural correlation becomes of great importance for the design and optimization of SSC for practical applications.

The history of the manufacture of the magnificent bronze castings produced in ancient China has been reinterpreted a number of times during the past hundred years or so. These bronzes were first believed to be fabricated by lost wax (cire perdue) casting, but this gave way to a belief that piece mold casting was the dominant, if not the sole method of manufacture from the Shang (1700-1100 BCE) until possibly as late as the Tang dynasty (618-907 CE). This has been reinforced by the finding, a number of years ago, of the Houma piece mold foundry, as well a number of more recent similar finds. However, this stance was challenged by the discovery of openwork bronze objects as early as in the 1920s, and more strongly challenged in the late 1970s by finds of intricately cast interwoven openwork bronze objects at the Tomb of the Marquis of Yi, dated to the Warring States Period (475-221 BCE). Since then many other similar bronze objects have been found. Questions exist concerning the very existence of the lost-wax process as early as the Spring and Autumn Period (771 to 476 BCE), and was it independently developed in China, or was it introduced from the outside.

Carbon nanotube (CNT) composites are being explored to improve the conductivity and density of electrical wire used in aviation. Presented are the current carrying capacity of a CNT-Cu composite and Roman spectroscopy and electrical conductivity of Buckypaper (BP) made of normal and sorted 95% metallic CNT (m-CNT). The ampacity of the Cu-CNT composite was 3.8% lower than pure Cu. This is significant because it is not in agreement with high CNT ampacity claims. The average conductivity of the CNT in the sorted, 95% metallic BP was 2.5 times higher than the CNT in the un-sorted BP. This shows the importance of the intrinsic CNT conductivity as opposed to interfacial resistances and that the conductivity of the semiconductor CNT present in the un-sorted BP must be much lower than the conductivity of m-CNT. The high conductivity of the sorted BP provides proof that conductivity improvements in CNT composites can be made by the use of sorted, highly conductive m-CNT.

Corrosion behavior of an API X70 steel by potentiodynamic polarization curves was carried out. X70 steel was heat treated at a temperature of 1050°C (onset temperature solution of niobium carbonitrides) for 15 and 30 minutes hold followed by quenching in water. Test solutions for electrochemical evaluation were NS4 solution and congenital water (CW) to assess external and internal corrosion pipelines respectively. The polarization curves were performed within a range of -500mV to 1000mV for NS4 solution and the -500mV to 600mV by congenital water respect to open circuit potential (OCP) at a scan rate of 1mV/s. The tests were conducted at room temperature. The surfaces of the samples were observed by scanning electron microscope (SEM). A localized corrosion type was observed. According to polarization curves it can be observed that oxidation reaction in the anodic branch belongs to a charge transfer process. Cathodic branches reveal a process where the charge transfer resistance is influenced by a process of mass transfer. The non-conventional heat treatment improved the corrosion resistance compared to as received material.

Molybdenum disulfide (MoS2) thin films were fabricated by two-step chemical vapor deposition (CVD) using (t-C4H9)2S2 and the effects of temperature, gas flow rate, and atmosphere on the formation were investigated in order to achieve high-speed low-temperature MoS2 film formation. From the results of X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) investigations, it was confirmed that c-axis orientation of the pre-deposited Mo film has a significant involvement in the crystal orientation after the reaction low temperature sulfurization annealing and we successfully obtained 3 nm c-axis oriented MoS2 thin film. From the S/Mo ratios in the films, it was revealed that the sulfurization reaction proceeds faster with increase in the sulfurization temperature and the gas flow rate. Moreover, the sulfurization under the H2 atmosphere promotes decomposition reaction of (t-C4H9)2S2, which were confirmed by XPS and density functional theory (DFT) simulation.

Ca3Co4O9 (CCO) is a promising material for thermoelectric applications; however, this layered oxide shows a large number of physical features that complicate understanding and systematically improving its properties. A significant component of CCO’s behavior is its magnetotransport properties, particularly in the low temperature region where an incommensurate spin density wave affects its band structure. In order to improve understanding in this area, we perform low temperature magnetoresistance (MR) measurements on a bulk CCO sample. Field-less resistivity measurements confirm the conventional behavior of our sample, with a metal-to-insulator transition at approximately 70 K, and a shoulder indicating ferrimagnetism at 14 K. Resistivity vs. temperature under applied magnetic field show significant MR below around 35 K.

The recent spotlight on supported nanoparticles (NPs) has attracted attention in the field of catalysis and fuel cell technology. Supported NPs can be used as model catalysts to gain a fundamental understanding of the catalytic properties at the interface. Here, especially the wet-chemical preparation of platinum NPs in alkaline ethylene glycol is a powerful approach to synthesize stable particles with a narrow size distribution in the nanometer regime. We combine high resolution imaging by scanning tunneling microscopy with electrochemical characterization by cyclic voltammetry to gain insights into the underlying degradation mechanism of supported platinum NPs, paving the way toward a rational design of supported catalysts with controlled activity and stability.

Replacing liquid by solid state electrolytes has the potential to significantly improve current Li ion batteries concerning performance and safety. The material class NZP, based on the compound NaZr2(PO4)3, exhibits a structural framework suitable for ionic conduction. In this work, a systematic compositional screening and simulation approach, combining classical molecular-dynamics, first-principles calculations, and structural analysis was applied, with which a set of new Li ion conducting NZP compounds could be identified.

Kappa (k-), iota (ɩ-), and lambda (λ-) Carrageenan (Car) microparticles were synthesized by crosslinking corresponding natural polymers with divinyl sulfone (DVS) via microemulsion polymerization/crosslinking methods for potential biomedical applications. Negatively charged e.g., -44 mV of Car particles were modified with diethylenetriamine (DETA) to generate positively charged modified (M-) ᴋ-Car particles with +23 mV zeta potential values. Cationic M-Car-DETA particles were found to be effectively antimicrobial material against gram negative bacteria, and some fungi species. Moreover, upon protonation of M-Car-DETA particles with HCl the effectiveness against all types of microorganisms are significantly increased. All types of Car based particles can be applicable for blood contacting material as low hemolysis ratio, 2.56% and high blood clotting capability, 86% were obtained. Furthermore, Car based particles found biocompatible against L929 fibroblast cells, and can induce necrotic cell death at 12.5 μg/mL concentration against DLD-1 colon cancer cells. M-ᴋ-Car-DETA particles were also demonstrated to be useful rending long term and linear drug release profiles using Rosmarinic Acid (RA) as a model drug.

Cordierite (Mg2Al4Si5O18), Mullite (Al4+2xSi2-2xO10-x) and Cordierite-Mullite ceramic materials were obtained from a stoichiometric mixture of coal fly ash (CFA) as a source of SiO2 and Al2O3, plus high-purity MgO and Al2O3. The starting stoichiometric mixtures were homogenized, and then uniaxially pressed, cold isostatically pressed, and sintered at 1200-1600 °C for 2-5 h. The sintered materials were characterized by X-ray diffraction, scanning electron microscopy, Vickers microhardness, density and four-point flexural strength. In general, the desired phases tended to form in the composites at temperatures of 1350 or 1400 °C, with a considerable amount of glassy phase developing from 3 h onwards at one of those two temperatures, depending on the composite composition. The microstructure of the composites consisted of a matrix of Cordierite and interwoven needles of Mullite. The bulk density decreased, while the flexural strength and the Vickers microhardness increased with increasing nominal content of Mullite in the composites. A synergistic effect taking place between Cordierite and Mullite enhances the mechanical properties of the composites.

While the most promising longitudinal recording systems cannot surpass the theoretical limit of about 200 Gb/in2 for areal recording density and the demand for higher densities is permanently increasing, the perpendicular magnetic recording constitutes the realistic issue to the longitudinal one. The perpendicular magnetic recording offers significant advantages, the most important being stronger write and read fields, and therefore the use of media of higher anisotropy, smaller grain size, higher signal-to-noise ratio, and a better thermal stability. Unfortunately, the perpendicular recording has to cope some important physical and technological difficulties. To overcome them, many ingenious solutions were proposed. In this paper the coupled granular/continuous (CGC) media, a subtle association of the continuous and, respectively, granular media, are analysed from the viewpoint of their magnetic and recording properties. The challenges and possible improvements of CGC media are discussed.