Different Response Kinetics to Temperature and Water Vapor of Acrylamide Polymers Obtained by Initiated Chemical Vapor Deposition

Thermoresponsive polymers undergo a reversible phase transition at their lower critical solution temperature (LCST) from a hydrated hydrophilic state at temperatures below the LCST to a collapsed hydrophobic state at higher temperatures. This results in a strong response to temperature when in aqueous environment. This study shows that hydrogel thin films synthesized by initiated chemical vapor deposition show fast and strong response to temperature also in water vapor environment. Thin films of cross-linked poly­(<i>N</i>-isopropylacrylamide), p­(NIPAAm), were found to have a sharp change in thickness by 200% in water vapor at temperatures above and below the LCST. Additionally, the stimuli-responsive poly­(<i>N</i>,<i>N</i>-diethylacrylamide) was investigated and compared to results found for p­(NIPAAm). Analysis of the swelling kinetics performed with in situ spectroscopic ellipsometry with variable stage temperature shows differences for swelling and deswelling processes, and a hysteresis in the thickness profile was found as a function of temperature and of temperature change rate

Thickness-Dependent Swelling Behavior of Vapor-Deposited Smart Polymer Thin Films

In this contribution, the temperature-dependent swelling behavior of vapor-deposited smart polymer thin films is shown to depend on cross-linking and deposited film thickness. Smart polymers find application in sensor and actuator setups and are mostly fabricated on delicate substrates with complex nanostructures that need to be conformally coated. As initiated chemical vapor deposition (iCVD) meets these specific requirements, the present work concentrates on temperature-dependent swelling behavior of iCVD poly­(<i>N</i>-isopropylacrylamide) thin films. The transition between swollen and shrunken state and the corresponding lower critical solution temperature (LCST) was investigated by spectroscopic ellipsometry in water. The films’ density in the dry state evaluated from X-ray reflectivity could be successfully correlated to the position of the LCST in water and was found to vary between 1.1 and 1.3 g/cm³ in the thickness range 30–330 nm. This work emphasizes the importance of insights in both the deposition process and mechanisms during swelling of smart polymeric structures

Opto-chemical control through thermal treatment of plasma enhanced atomic layer deposited ZnO

Properties and performance of materials are closely connected. In order to obtain piezoelectric and lasing optical quality, ZnO has to be free of defects and highly crystalline. Instead, conductivity depends upon such defects, making it not trivial to aim at a specific set of properties in a single step. In this regard, we studied in situ the effect of temperature as an additional knob to finely control such properties. In this contribution, plasma enhanced atomic layer deposited (PE-ALD) zinc oxide (ZnO) layers, deposited between 25 °C and 250 °C, were studied in situ during annealing in air, and the opto-chemical and structural characteristics of the oxides were followed as a function of temperature. In situ spectroscopic ellipsometry (SE) and X-ray diffraction (XRD) were adopted to identify temperature windows where major structural and optical changes in the material occurred. Two temperature regions were identified for the effusion of adsorbed gases and minor structural rearrangements (180–280 °C) and for the growth/coalescence of ZnO crystals and its densification (360–500 °C). The results were corroborated by ex situ SE, XRD, UV–Vis and X-ray photoelectron spectroscopy. The in situ study revealed differences among the ZnO layers deposited at different temperatures, giving additional insights on the material properties deposited by PE-ALD

Quality of images with toric intraocular lenses

Purpose: To objectively evaluate the image quality obtained with toric intraocular lenses (IOLs) when misaligned from the intended axis. Setting: University Eye Clinic and the Department of Industrial and Information Engineering, University of Trieste, Trieste, Italy. Design: Experimental study. Methods: An experimental optoelectronic test bench was created. It consisted of a high-resolution monitor to project target images and an artificial eye. The system simulates the optical and geometric characteristics of the human eye with an implanted toric IOL. A 3.00 diopters corneal astigmatism was simulated. Images reproduced by the optical system were captured according to different IOL axis positions. The quality of each image was analyzed using the visual information fidelity (VIF) criterion. The VIF reduction was calculated at each IOL rotational step. Results: A 5-degree IOL axis rotation from the intended position determined a decay in the image quality of 7.03%. Ten degrees of IOL rotation caused an 11.09% decay of relative VIF value. For a 30-degree rotation, the VIF decay value was 45.85%. Finally, the image decay with no toric correction was 56.70%. Conclusions: The more the objective quality of the image decays progressively, the further the axis of the IOL is rotated from its intended position. The reduction in image quality obtained after 30 degrees of toric IOL rotation was less than 50% and after 45 degrees, the image quality was the same as that of no toric correction

On the transformation of "zincone"-like into porous ZnO thin films from sub-saturated plasma enhanced atomic layer deposition

The synthesis of nanoporous ZnO thin films is achieved through annealing of zinc-alkoxide (“zincone”-like) layers obtained by plasma-enhanced atomic layer deposition (PE-ALD). The zincone-like layers are deposited through sub-saturated PE-ALD adopting diethylzinc and O2 plasma with doses below self-limiting values. Nanoporous ZnO thin films were subsequently obtained by calcination of the zincone-like layers between 100–600 °C. Spectroscopic ellipsometry (SE) and X-ray diffraction (XRD) were adopted in situ during calcination to investigate the removal of carbon impurities, development of controlled porosity, and formation and growth of ZnO crystallites. The layers developed controlled nanoporosity in the range of 1–5%, with pore sizes between 0.27 and 2.00 nm as measured with ellipsometric porosimetry (EP), as a function of the plasma dose and post-annealing temperature. Moreover, the crystallinity and crystallite orientation could be tuned, ranging from a powder-like to a (100) preferential growth in the out-of-plane direction, as measured by synchrotron-radiation grazing incidence XRD. Calcination temperature ranges were identified in which pore formation and subsequent crystal growth occurred, giving insights in the manufacturing of nanoporous ZnO from Zn-based hybrid materials

New System Delivering Microwaves Energy for Inducing Subcutaneous Fat Reduction: In - Vivo Histological and Ultrastructural Evidence

BACKGROUND: Recently, it has been developed a new technology for the reduction of subcutaneous adipose tissue through a non-invasive treatment by microwaves. The main objective of the present study is to demonstrate the feasibility of utilising a non-invasive, localised microwaves (MW) device to induce thermal modifications into subcutaneous adipose tissue only by a controlled electromagnetic field that heats up fat preferentially. This device is provided with a special handpiece appropriately cooled, directly contacting the cutaneous surface of the body, which provides a calibrated energy transfer by microwaves. AIM: In this paper, microscopic and ultrastructural modifications of subcutaneous adipose tissue induced by microwaves irradiation are evaluated. METHODS: Our experimental plan was designed for collecting biopsy samples, for each skin region treated with a single irradiation session, 1) before treatment (control), 2) immediately after treatment, 3) after 6 hrs, 4) after 1 month, 5) after 2 months. Bioptic samples from each step were processed for light microscopy and transmission electron microscopy. At the same time, each region where biopsies were collected was subjected to ultrasound examination. Recorded images permitted to evaluate the thickness of different layers as epidermis, dermis, hypodermis, connective fasciae, until to muscle layer, and related modifications induced by treatment. RESULTS: In every biopsy collected at different time-steps, epidermis and superficial dermis appeared not modified compared to control. Differently, already in the short-term biopsies, in the deep dermis and superficial hypodermis, fibrillar connective tissue appeared modified, showing reduction and fragmentation of interlobular collagen septa. The most important adipose tissue modifications were detectable following 1 month from treatment, with a significant reduction of subcutaneous fat, participating both the lysis of many adipocytes and the related phagocytic action of monocytes/macrophages on residuals of compromised structures of adipocytes. In the samples collected two months following treatment, the remnants of adipose tissue appeared normal, and macrophages were completely absent. CONCLUSIONS: Ultrasound, microscopic and ultrastructural evidence are supporting significant effectiveness of the new device treatment in the reduction of subcutaneous fat. In this paper, the possible mechanisms involved in the activation of the monocytes/macrophages system responsible for the removal of adipocytes residuals have also been discussed