Conceptual Developments of Aryldiazonium Salts as Modifiers for Gold Colloids and Surfaces.

Modified colloids and flat surfaces occupy an important place in materials science research due to their widespread applications. Interest in the development of modifiers that adhere strongly to surfaces relates to the need for stability under ambient conditions in many applications. Diazonium salts have evolved as the primary choice for the modification of surfaces. The term "diazonics" has been introduced in the literature to describe "the science and technology of aryldiazonium salt-derived materials". The facile reduction of diazonium salts via chemical or electrochemical processes, irradiation stimuli, or spontaneously results in the efficient modification of gold surfaces. Robust gold-aryl nanoparticles, where gold is connected to the aryl ring through bonding to carbon and films modified by using diazonium salts, are critical in electronics, sensors, medical implants, and materials for power sources. Experimental and theoretical studies suggest that gold-carbon interactions constructed via chemical reactions with diazonium salts are stronger than nondiazonium surface modifiers. This invited feature article summarizes the conceptual development of recent studies of diazonium salts in our laboratories and others with a focus on the surface modification of gold nanostructures, flat surfaces and gratings, and their applications in nanomedicine engineering, sensors, energy, forensic science, and catalysis.

Development of Latent Fingerprints via Aryldiazonium Tetrachloroaurate Salts on Copper Surfaces: An XPS Study.

Surface studies of developed fingerprints have aided in the elimination of criminal cases before moving to the court. The combination of X-ray photoelectron spectroscopy (XPS) with the aryldiazonium gold(III), 4-O2NC6H4N2+AuCl4-, surface modifier has been shown to be a novel approach in latent fingerprint detection and development for the quantification of film elements. The robust gold-aryl film was developed on the reducing chemicals excreted in the sebaceous fingerprints without the need for external stimuli and at a lesser extent after contacting the free metal surface. The concurrent reduction of the diazonium functional group and gold(III) from [AuCl4]- developed a robust gold-aryl film, which showed increasing gold(0) quantity in the time range of 30-120 min over copper coins and model flat sheets. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) support the presence of reduced gold on the top of the latent fingerprints and the presence of CuO resulting from the reaction of the diazonium salt with copper metal. This research combines the quantification of deposits using XPS, a surface-sensitive technique for chemical analysis, in addition to surface imaging.

Dual-Responsive Hydrogels for Mercury Ion Detection and Removal from Wastewater.

This study describes the development of a fast and cost-effective method for the detection and removal of Hg2+ ions from aqueous media, consisting of hydrogels incorporating chelating agents and a rhodamine derivative (to afford a qualitative evaluation of the heavy metal entrapment inside the 3D polymeric matrix). These hydrogels, designed for the simultaneous detection and entrapment of mercury, were obtained through the photopolymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) and N-vinyl-2-pyrrolidone (NVP), utilizing N,N'-methylenebisacrylamide (MBA) as crosslinker, in the presence of polyvinyl alcohol (PVA), a rhodamine B derivative, and one of the following chelating agents: phytic acid, 1,3-diamino-2-hydroxypropane-tetraacetic acid, triethylenetetramine-hexaacetic acid, or ethylenediaminetetraacetic acid disodium salt. The rhodamine derivative had a dual purpose in this study: firstly, it was incorporated into the hydrogel to allow the qualitative evaluation of mercury entrapment through its fluorogenic switch-off abilities when sensing Hg2+ ions; secondly, it was used to quantitatively evaluate the level of residual mercury from the decontaminated aqueous solutions, via the UV-Vis technique. The ICP-MS analysis of the hydrogels also confirmed the successful entrapment of mercury inside the hydrogels and a good correlation with the UV-Vis method.

Physicochemical Properties of Organic Molecular Ferroelectric Diisopropylammonium Chloride Thin Films.

We fabricated ferroelectric films of the organic molecular diisopropylammonium chloride (DIPAC) using the dip-coating technique and characterized their properties using various methods. Fourier-transform infrared, scanning electron microscopy, and X-ray diffraction analysis revealed the structural features of the films. We also performed ab-initio calculations to investigate the electronic and polar properties of the DIPAC crystal, which were found to be consistent with the experimental results. In particular, the optical band gap of the DIPAC crystal was estimated to be around 4.5 eV from the band structure total density-of-states obtained by HSE06 hybrid functional methods, in good agreement with the value derived from the Tauc plot analysis (4.05 ± 0.16 eV). The films displayed an island-like morphology on the surface and showed increasing electrical conductivity with temperature, with a calculated thermal activation energy of 2.24 ± 0.03 eV. Our findings suggest that DIPAC films could be a promising alternative to lead-based perovskites for various applications such as piezoelectric devices, optoelectronics, sensors, data storage, and microelectromechanical systems.

Silicone Oil Utilized in Pars Plana Vitrectomy for Patients with Advanced Proliferative Diabetic Retinopathy: Physico-Chemical and Optical Properties.

Objective: Silicone oils have the role in maintaining the attachment of the retina in conditions where the risk of retinal re-detachment is high. However, silicone oils have the tendency to emulsify with subsequent complications. In this work, analyses have been performed to understand changes that occurred to the optical, and physical characteristics of the oil after removal from the vitreous cavity of patients underwent pars plana vitrectomy (PPV) for fibrovascular membranes/tractional retinal detachment (FVM/TRD). Methods: Four samples of silicone oil were allocated from patients who underwent PPV for FVM/TRD. The Fourier-transform infrared (FTIR) spectroscopy, micro-viscometry, and ultraviolet-visible spectrometer analyses were utilized to determine the changes in its chemical bondings, viscosity, absorbance, transmittance, buoyance, and specific gravity. Results: The mean age of the patients was 49.0 years. The mean duration of silicone oil implantation was 18.9 months. FTIR analysis showed significant breaking in the chemical bonding that was related to the lens status during the primary PPV, the presence of significant retinal hemorrhages, the duration of silicone oil implantation, and the degree of silicone oil filling. Similarly, viscosity and contact angle analyses revealed a reduction in the viscosity with similar factors to the FTIR analysis. Moreover, absorbance and transmittance were largely affected by the aggressiveness of FVM/TRD. Conclusion: This study revealed that certain factors such as the age of the patient, duration of silicone oil implantation, lens status, and the presence of retinal hemorrhages, the degree of silicone oil filling and aggressiveness of FVM/TRD may contribute to the emulsification process.

Photoisomerization Kinetics of Photoswitchable Thin Films Based on Nanostructure/Molecular Layers of AlN-AO7.

The photoisomerization kinetics of photoswitchable thin films based on nanostructure/molecular layers of AlN-AO7 have been studied, investigated and reported. The trans → cis isomerization process occurs by UV-light irradiation. The cis-isomer could be turned back to the trans-isomer by either thermal or optical relaxation. The kinetics and time-evolution of the photoisomerization and reverse isomerization mechanism of AlN-AO7 thin films are investigated by UV-Vis absorbance spectra using relevant models. All phases of AlN-AO7 thin film, initial trans-, cis-, optical trans-, thermal trans-phases, were investigated using UV-Vis absorbance spectra, FTIR spectra, XRD and SEM. Transforming AlN-AO7 thin film from the initial trans-phase into cis-phase leads to curvature in the AO7 leaves and increases in the strain inside the structure. Going back to the trans-phase by either optical or thermal relaxation leads to vanishing the curvature and decreasing the structure's strain. Finally, the energy storage capacity was calculated using DSC and was found to be 36.38 J g-1 , simultaneously realizing the multisource solar energy storage and environmental heat.

Computational and experimental characterizations of annealed Cu2ZnSnS4 thin films.

We report on the synthesis and characterization of Cu2ZnSnS4 (CZTS) thin films prepared at different annealing temperatures using the sol-gel method and deposited on glass substrates using the immersing method. The XRD analysis demonstrates that the films annealed at 450 °C exhibit the most stable tetrahedral kesterite structure. Computationally, the Vienna ab initio simulation package (VASP) has been implemented to calculate critical structural properties of as-prepared CZTS) thin films and compared with those extracted from the XRD patterns. An excellent agreement is obtained between the calculated and measured structural parameters. Optical measurement of key optical parameters of annealed CZTS thin films shows a drastic manipulation of all-optical properties compared to the as-prepared thin films. In particular, an optical band gap of 1.62 eV obtained for annealed CZTS thin films at 450 °C makes them eligible to be potential candidates for thin film-based high-efficiency solar cells. Calculations of elastic properties of annealed thin films reveal that crystallite size increases and microstrain decrease compared with those of as-prepared thin films. The sheet resistance of annealed CZTS thin films exhibits a significant decline as the annealing temperature is increased. The electrical properties of annealed CZTS thin films could match some conductors. Remarkably, at 450 °C annealing temperature, the sheet resistance decreases to 74 Ω.cm-1 indicating the possibility of using the annealed CZTS thin films for efficient and low cost solar cell applications.

Synthesis and Characterization of Thin Films Based on Azobenzene Derivative Anchored to CeO2 Nanoparticle for Photoswitching Applications.

Azobenzene has attracted substantial attention as a photoswitchable molecule since its applications range from energy and data storage to biomedical applications. This work reports a new type of thin-film based on azobenzene derivative anchored to cerium oxide nanoparticles CeO2 NPs for photoswitching applications. The trans-cis isomerization and reverse isomerization occur by UV-light exposure and thermal relaxation process, respectively. The photoisomerization and reverse isomerization kinetics for CeO2 NPs-MR thin films are studied, investigated, and analyzed using UV-Vis absorbance spectra, FTIR spectroscopy, XRD, and scanning electron microscopy (SEM), in addition to differential scanning calorimetry (DSC) measurement to study the energy storage capacity. The results found that anchoring azobenzene to CeO2 NPs is successful in multisource storage of solar energy applications.

Optical and Physical Properties of Silicone Oil Extracted from the Vitreous of Patients Who Underwent Vitrectomy for Retinal Detachment.

Purpose: Silicone oil (SO) is a crucial tool in vitreoretinal surgery. SO has the tendency to emulsify depending on certain factors. In this work, detailed analyses have been conducted to understand changes that occurred to the physical, optical, and chemical characteristics of the oil after removal from the vitreous cavity. Methods: Five samples of SO were collected from patients who underwent vitrectomy for rhegmatogenous retinal detachment. The fourier-transform infrared (FTIR) spectroscopy, ultraviolet-visible spectrometer, and contact angle analysis were utilized to determine the changes in its chemical bondings, transmittance, absorbance, viscosity, buoyance, and specific gravity. Results: FTIR analysis showed significant changes in the chemical bonding that might be related to the age of the patient, lens status, the presence of retinal hemorrhages, and the exposure to laser after implantation of SO. In addition, contact angle analysis revealed that the viscosity might be affected by duration of implantation and the age of the patient. Moreover, transmittance and absorbance were largely affected by the exposure to laser retinopexy after implantation. Conclusion: This study showed that certain factors such as the age of the patient, the exposure to laser, lens status, and the presence of retinal hemorrhages may contribute to the emulsification process.

Optical characterizations of PMMA/metal oxide nanoparticles thin films: bandgap engineering using a novel derived model.

We synthesize and optically characterize pure PMMA and PMMA incorporated with metal oxides nanoparticles (MO NPs) such as ZnO, CuO, TiO2 and SiO2 NPs nanocomposite thin films with weight concentration of 10% using dip-coating technique. SEM images of MO NPs show that all NPs have nearly an average size of around 50 nm. The optical parameters such as, optical parameters (n and k), optoelectronics properties, dispersion, band-gap energy and band structure of as-prepared nanocomposite thin films were determined by analyzing the transmittance and reflectance spectra. Mainly, optical band-gap energy (E g) and the thickness of thin films are evaluated to a high degree of accuracy by utilizing Q-functional derived using a mathematical model recently published. The Q(E) is a functional containing experimental transmission and reflection data and the incident photon energy. The E g value of un-doped PMMA thin films is found to be 4.273 eV. This value decreases as pre-selected MO NPs are introduced into thin films. These values are in excellent agreement with those determined using Tauc method. The FTIR technique is employed to elucidate the vibrational bands of the nanocomposites and the intermolecular bonding between PMMA matrix and the MOs NPs. Thermal stability is investigated by employing thermogravimetric analysis (TGA) at temperatures up to 400 °C. The obtained TGA thermograms indicate that adding MOs NPs to PMMA yield thin films of better thermal stability. The obtained doped thin films show a great promise for fabricating high-efficient optoelectronic devices.

Synthesis of Optically Tunable and Thermally Stable PMMA-PVA/CuO NPs Hybrid Nanocomposite Thin Films.

We report the synthesis and comprehensive characterization of polymethylmethacrylate (PMMA)/polyvinylalcohol (PVA) polymeric blend doped with different concentrations of Copper oxide (CuO) nanoparticles (NPs). The PMMA-PVA/CuO nanocomposite hybrid thin films containing wt.% = 0%, 2%, 4%, 8%, and 16% of CuO NPs are deposited on glass substrates via dip-coating technique. Key optical parameters are measured, analyzed, and interpreted. Tauc, Urbach, Spitzer-Fan, and Drude models are employed to calculate the optical bandgap energy (Eg) and the optoelectronic parameters of PMMA-PVA/CuO nanocomposites. The refractive index and Eg of undoped PMMA-PVA are found to be (1.5-1.85) and 4.101 eV, respectively. Incorporation of specific concentrations of CuO NPs into PMMA-PVA blend leads to a considerable decrease in Eg and to an increase of the refractive index. Moreover, Fourier Transform Infrared Spectroscopy (FTIR) transmittance spectra are measured and analyzed for undoped and doped polymeric thin films to pinpoint the major vibrational modes in the spectral range (500 and 4000 cm-1) as well as to elucidate the nature of chemical network bonding. Thermogravimetric analysis (TGA) is conducted under appropriate conditions to ensure the thermal stability of thin films. Doped polymeric thin films are found to be thermally stable below 105 °C. Therefore, controlled tuning of optoelectronic and thermal properties of doped polymeric thin films by introducing an appropriate concentration of inorganic fillers leads to a smart design of scaled multifunctional devices.

Optical, Structural, and Crystal Defects Characterizations of Dip Synthesized (Fe-Ni) Co-Doped ZnO Thin Films.

Sol-gel technique is used to synthesize as-grown zinc oxide (ZnO) and iron-nickel (Fe-Ni) co-doped ZnO thin films deposited on glass substrates using dip coating technique. The structural properties and crystal imperfections of as-prepared thin films are investigated. We performed the structural analysis of films using X-ray diffraction (XRD). The XRD analysis reveal that the as-prepared films exhibit wurtzite structure. Furthermore, XRD-line profile analysis is performed to study the correlation between structural properties and imperfections of the nanocomposite thin films. The crystallite size and microstrains parameters are predicted using the Williamson-Hall method. We found that the crystallites size increases as the co-doped (Fe-Ni) concentration is increased. However, microstrains of the nanocomposite films decreases as (Fe-Ni) concentration is increased. The optical properties of the (Fe-Ni) co-doped nanocomposite films are investigated by performing UV-Vis (250 nm-700 nm) spectrophotometer measurements. We found that as the (Fe-Ni) concentration level is steadily increased, transmittance of the undoped ZnO thin films is decreased. Remarkably, refractive index of undoped ZnO thin films is found to exhibit values extending from 1.55 to1.88 that would increase as (Fe-Ni) concentration is increased.

Pattern of renal diseases among elderly Egyptians patients with acute or chronic renal diseases in Ain Shams University and Nasser Institute Hospitals, Cairo, Egypt.

This study among elderly renal Egyptian patients (n=220) with only 20 of them were subjected to renal biopsy. Results showed: diabetic nephropathy in 28.2%, hypertensive nephrosclerosis 25.5%, UTI, cystitis and pyelonephritis in 6.8%, renal stones in 5.9%, obstructive uropathy in 7.6%, simple cysts in 4.5%, CRF of unknown origin in 13.1%, and others in 26.4%. DM and HTN were S related to kidney function tests and increase in elderly. Other cardiovascular risk factors and smoking are reported by previous workers to be HS related to renal diseases. Age was significantly related to GFR, BUN and Cr. but sex difference was not significantly related to renal diseases. Multiple myeloma, lupus nephritis, vasculitis and hepatitis B were all recorded in few numbers of elderly Egyptians. HCV was more common and more likely to cause renal diseases. Abdomino-pelvic ultrasound was confirmatory to clinical renal diseases diagnosis. Among patients (n=20) biopsies showed focal necrotizing GN in 20%, membranous nephropathy in 50% and renal amyloidosis in 30%. CTIN was associated in some cases due to NSAID intake. Analgesic nephropathy was a common problem that might lead to ARF in some cases especially in the elderly. Ultrasound results among the biopsy group were confirmatory to clinical diagnosis.