Some properties and fast algorithms of slant transform in image processing

A first order stationary Markov process model has been considered for image processing problems. A relative performance measure of unitary transforms to image data has been defined. It has been proved that the slant transform is superior to Walsh-Hadamard transform in this relative performance measure for positive correlation under the assumed model. A lower bound of relative performance has also been found. Furthermore, fast algorithms for computing diagonal elements of any slant transformed matrix have been presented. Finally, it has been shown how slant transform can be modified to improve the relative performance.     

Investigation of Zr-doped ceria for solar thermochemical valorization of CO2

This study belongs to the estimation of the CO₂ conversion ability of Ce_1−xZr _xO₂ (CZ) materials performing multiple thermogravimetric CO₂ splitting (CDS) cycles. By varying the molar concentrations of Zr in the range of 0.05 to 0.5, the CZ materials were prepared by using co-precipitation method. By employing various analytical methods, the physical properties such as phase and elemental composition, crystallite size, and particle morphology of the as-synthesized CZ materials were recognized. The systematic estimation of the reactivity of each CZ material was performed by conducting multiple cycles in a thermogravimetric analyzer (TGA). Obtained findings indicated that Ce_0.7Zr_0.3O₂ (CZ30) and Ce_0.85Zr_0.15O₂ (CZ15) were proficient towards producing maximum amounts of O₂ () and CO ( n_CO ) than other CZ materials. It was further understood that, to achieve higher and n_CO as compared with CeO₂, the molar concentration of the Zr should be in the range of 15% to 35%.     

Study of electrical properties of polymeric materials using electrochemical impedance spectroscopy

Electrochemical impedance spectroscopy (EIS) has been used to determine the water absorption characteristics of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyaromatic amide (Aramid), and amine–quinone polyurethane (AQ) free-standing polymer films. A method for calculating percent moisture uptake is presented based on capacitance measurements via EIS, which requires initial or “dry” capacitance values, C₀. Three different methods for obtaining C₀ values were described and employed, but the most reliable values were obtained via EIS measurement using Hg contacts. C₀ values obtained by this method resulted in calculated water uptake values nearly identical to those obtained by measured weight gain. Lower capacitance values were observed for films immersed in distilled water compared to 0.1M NaCl, which indicates that water uptake is greater in NaCl than in pure water. The four polymers examined in this study can be listed in order of decreasing resistance to moisture absorption as AQ > PET > PEN > Aramid. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 553–560, 1998     

Barrier properties of electron‐beam‐modified EPDM rubber

EPDM rubber was surface‐ and bulk‐modified with varying concentrations of trimethylol propane triacrylate (TMPTA) in the presence of a constant electron‐beam irradiation dose of 100 kGy and over a wide range of irradiation doses from 0 to 200 kGy at a fixed TMPTA concentration (10%). The permeation rate and absorption of three homologous nonpolar solvents, namely, n‐hexane, n‐heptane, and n‐octane, along with an aromatic solvent, toluene, and a polar solvent, trichloroethylene, through unirradiated, unmodified control, and modified rubber membranes (≈150 μm) were studied. It was found that both the permeation rate and absorption decrease progressively with increase in the TMPTA concentration up to 10% for both the surface‐ and bulk‐modified rubbers. With increase in the radiation dose, there also is an initial drop in the values up to 50 kGy for the control and surface‐modified rubbers and up to about 100 kGy for the bulk‐modified one. The control rubber shows the highest absorption and permeation for all the solvents except trichloroethylene, followed by the bulk‐modified rubber membrane. Trichloroethylene is, however, absorbed and permeated most by the surface‐modified sample. The observations are explained in terms of the structural modifications of the rubber, crosslinking, changes in the relevant thermodynamic properties such as surface energy, the penetrant size, and the transport mechanism of the penetrants. The influence of temperature on the permeability characteristics of the control and modified rubbers was also studied. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 784–795, 2000     

Investigation of polycrystalline lead titanate fibers and thin films by micro-Raman spectroscopy

Lead titanate thin films and fibers were prepared by sol-gel technique and the phase formation behavior, surface morphology and the effect of strain on the microstructural features of these samples was investigated. The x-ray and micro-Raman scattering results indicate the formation of the tetragonal perovskite phase in both films and fibers. The analysis of the Raman phonon modes reveals that the film is more stressed than the fibers. The variation of stress has been correlated to the microstructural features in these structures.     

Transforming covalent organic framework into thin-film composite membranes for hydrocarbon recovery

We, for the first time, employed chemically stable covalent organic framework (COF) (TpPa-1) as a transport-active phase within the polymer (styrene-butadiene rubber; SBR) matrix to make TpPa-1@SBR thin-film composite (TFC) membranes. Three composite membranes, viz., TpPa-1(30)@SBR, TpPa-1(50)@SBR, and TpPa-1(70)@SBR have been prepared with varying COF content. These membranes were characterized for gas permeance and results were compared with the pristine SBR-based TFC membrane. The fully organic nature of chemically stable COF offered good compatibility with the host polymer matrix (SBR) and resulted into flexible TFC membranes even at 70% of COF loading; compared to the other porous material (MOFs or Inorganic fillers), it is appreciable.     

Multiphase Assembly of Small Molecule Microcrystalline Peptide Hydrogel Allows Immunomodulatory Combination Therapy for Long‐Term Heart Transplant Survival

Combination therapies that target multiple pathways involved in immune rejection of transplants hold promise for patients in need of restorative surgery. Herein, a noninteracting multiphase molecular assembly approach is developed to crystallize tofacitinib, a potent JAK1/3 inhibitor, within a shear‐thinning self‐assembled fibrillar peptide hydrogel network. The resulting microcrystalline tofacitinib hydrogel (MTH) can be syringe‐injected directly to the grafting site during surgery to locally deliver the small molecule. The rate of drug delivered from MTH is largely controlled by the dissolution of the encapsulated microcrystals. A single application of MTH, in combination with systemically delivered CTLA4‐Ig, a co‐stimulation inhibitor, affords significant graft survival in mice receiving heterotopic heart transplants. Locoregional studies indicate that the local delivery of tofacitinib at the graft site enabled by MTH is required for the observed enhanced graft survival.