Publications by authors named "Samuel Lofland"
Article Synopsis
- Non-contact in situ techniques, like low-frequency Raman spectroscopy, can enhance resin formulation and processing by effectively monitoring cure kinetics.
- Recent studies reveal a connection between structural conversion, related to rheological properties, and chemical conversion, although the latter shows no direct correlation in their data.
- The research successfully combines structural and chemical conversion data to create master cure kinetics curves, linking them with a semi-empirical model for storage shear modulus as curing progresses.
Article Synopsis
- Understanding how resin cures is vital for linking the properties of polymers to their processing and structure.
- The Raman spectrum's disorder band indicates changes in material characteristics as resin polymerizes, which can be normalized to track structural conversion kinetics versus chemical conversion kinetics.
- Our findings show that while structural and chemical conversions happen at the same time during the primary network formation, there is a delay between them in the secondary network formation.
Article Synopsis
- The substitution of Ru by Ta in SrYbRuO leads to changes in its magnetic properties, showing stronger antiferromagnetic interactions in pure SrYbRuO compared to its Ta-substituted variants.
- As the concentration of Ta increases, the band gap of the material increases nearly linearly, indicating shifts in electronic structure and orbital ordering.
- The photoelectrocatalytic studies reveal that SrYbRuO has the highest photocurrent density and optimal performance for oxygen evolution reactions, with structural insights gained from techniques like XPS and EPR confirming the oxidation states and the presence of oxygen vacancies.
Article Synopsis
- Electrical switching of ferroelectric domains enhances piezoelectric activity but typically reduces optical transparency due to light scattering at domain boundaries.
- Researchers demonstrated that ferroelectric domains in specific perovskite crystals can be manipulated to convert an opaque structure into a transparent one with low electric fields, maintaining strong piezoelectric properties.
- This dual control over optical and piezoelectric characteristics opens up opportunities for developing advanced photonic devices.
Article Synopsis
- - This study explores the combination of silk protein's properties, like biocompatibility and flexibility, with three types of magnetic nanoparticles to assess their structure and potential uses in sustainability and biomaterials.
- - Infrared spectroscopy revealed that certain magnetic nanoparticles (magnetite and barium hexaferrite) inhibit the formation of β-sheet structures in silk protein due to strong bonding with its components, while cobalt has minimal impact.
- - The magnetic composites showed high magnetization and stability even after high-temperature degradation, suggesting promising applications in medical fields such as MRI imaging, tissue regeneration, and drug delivery.
The combination of protein and polysaccharides with magnetic materials has been implemented in biomedical applications for decades. Proteins such as silk, collagen, and elastin and polysaccharides such as chitosan, cellulose, and alginate have been heavily used in composite biomaterials. The wide diversity in the structure of the materials including their primary monomer/amino acid sequences allow for tunable properties.
View Article and Find Full Text PDFFormic Acid Regenerated Mori, Tussah, Eri, Thai, and Muga Silk Materials: Mechanism of Self-Assembly.
ACS Biomater Sci Eng
December 2019
Article Synopsis
- Flexible and water-insoluble regenerated silk materials show promise for various medical applications due to their unique mechanical properties.
- * In this study, five types of silk films were created using a specific method (formic acid-calcium chloride) and analyzed using various techniques to compare their physical properties.
- * Results indicated that the silk films exhibit different structural features compared to natural silk fibers, suggesting that intramolecular β-sheet structures contribute to their water insolubility and flexibility, paving the way for advancements in silk-based biomaterials.
Article Synopsis
- * The increasing demand for biocompatible materials with varying thermal conductivity aligns with advancements in flexible materials and bioelectronics technologies.
- * This review examines the structure of fibrous proteins (like silk, collagen, and keratin) and discusses how their nano-scale structures impact thermal conductivity, along with methods for measuring their heat transfer properties.
Article Synopsis
- The study presents several new complexes and coordination polymers derived from 15-metallacrown-5 structures that incorporate lanthanide (Ln) and copper (Cu) ions with glycinehydroxamate (GlyHA) and m-phthalate (m-bdc) ligands.
- Compounds 1 and 3 feature unique quadruple-decker metallacrown assemblies, while compounds 2 and 4 form one-dimensional coordination polymers with solvent-filled crystal lattices.
- The absorption studies reveal that desolvated compound 4 can uptake methanol and ethanol vapors, and the analysis of magnetic properties shows significant exchange interactions between the metal ions in these complexes.
Article Synopsis
- The study focuses on creating and analyzing silver oxide films (AgO and Ag₂O) intended to be used as antibacterial coatings to prevent bacterial growth.
- The coatings are effective against various bacterial strains, showing the ability to kill bacteria and inhibit growth both on solid media and in liquid culture.
- The release of silver ions from these coatings is influenced by the complexity of the surrounding media, demonstrating strong antibacterial properties while having minimal short-term toxic effects on mammalian cells.
Article Synopsis
- Multiferroic heterostructures are created using Pb(Zr0·52Ti0·48)O3 and Fe0.7Ga0.3 thin films on Si cantilevers, allowing for advanced integration.
- These structures operate in a non-linear regime, enhancing the coupling between mechanical and magnetic/electric properties.
- Bistable dynamic states are developed that can be switched back and forth using DC magnetic and electric fields, enabling tunability of the resonant frequency.
Article Synopsis
- Magnetoelectric oxide heterostructures are targeted for use in spintronic memory and logic devices, which use spin transport to convey information.
- The study presents local measurements showing how strain and charge affect magnetization in a specific material system (La0.7Sr0.3MnO3/PbZr0.2Ti0.8O3) using advanced spatial characterization techniques.
- The findings indicate that local structural changes and charge screening alter magnetization, which can be fine-tuned by adjusting the thickness of the material layers, impacting future device technologies.
Article Synopsis
- - Hybrid nanobeads featuring manganese-oxo or manganese-iron-oxo clusters were successfully created using the miniemulsion polymerization method.
- - New metal-oxo clusters, Mn(12)O(12)(VBA)(16)(H(2)O)(4) and Mn(8)Fe(4)O(12)(VBA)(16)(H(2)O)(4), were synthesized and characterized, introducing a functional group (4-vinylbenzoate or VBA) into the clusters.
- - The resulting polymer nanoparticles, formed from these clusters and styrene, were uniform in size and measured around 60 nm in diameter, with comprehensive analysis conducted on their properties and structure.
Article Synopsis
- * The synthesis process involves adjusting the niobium precursor to boron ratio and reaction conditions to produce various nanostructures, including core-shell structures, and was characterized using techniques like XRD, HRTEM, and EDX.
- * Niobium diboride nanorods exhibit superconductivity with a critical transition temperature of 6.4 K, but this superconductivity is hidden in the core-shell structure
Article Synopsis
- Researchers created nickel borate nanostructures with specific sizes and shapes using a method involving a precursor made in microemulsions with Tergitol as a surfactant.
- By experimenting with different co-surfactants like 1-butanol, 1-hexanol, and 1-octanol, they produced uniform nanorods and nanospindles of varying dimensions.
- The resulting nanorods exhibited antiferromagnetic properties, with a Néel temperature between 44 to 47 K, and showed an increase in magnetic moment as the rods became thinner.
Article Synopsis
- Appropriate microemulsion systems were used to produce hexagonal cobalt and cobalt-nickel alloy nanoparticles with cetyltrimethylammonium bromide as a surfactant at high temperatures, achieving stabilization of hexagonal cobalt at very small sizes.
- Annealing hcp cobalt nanoparticles in hydrogen at 700 degrees Celsius transformed them into fcc cobalt nanoparticles, with microscopy revealing spherical nanoparticles in different sizes and structures.
- Electrochemical tests indicated that cobalt nanoparticles outperform cobalt-nickel alloy nanoparticles at voltages below 0.65 V, whereas the alloy shows better efficiency at higher voltages, and all nanoparticles display ferromagnetism, though saturation magnetization is reduced due to potential surface oxidation.
Surface attached manganese-oxo clusters as potential contrast agents.
Chem Commun (Camb)
February 2009
Article Synopsis
- * This stabilization made it possible to study how well the cluster could be used as a contrast agent for MRI scans.
- * The research focused on the potential benefits of using Mn-12 in medical imaging.
Rod-shaped nanostructures of cobalt oxalate dihydrate were synthesized at room temperature by the microemulsion (reverse micellar) route. These rods are highly uniform in length and can be modified with temperature (from approximately 6.5 microm at 50 degrees C to approximately 2.
View Article and Find Full Text PDFNanorods of copper and nickel oxalates synthesized by the reverse micellar route.
J Nanosci Nanotechnol
November 2005
Article Synopsis
- * The synthesized nickel and copper nanorods have diameters of 250 nm and 130 nm, respectively, with lengths of about 2.5 microm for nickel and 480 nm for copper, and their shape can be altered by changing the solvent used.
- * Nickel oxalate nanorods exhibit an antiferromagnetic transition at 34 K, while copper oxalate nanorods show temperature-independent paramagnetism.