Dynamic Compression of in situ Grown Living Polymer Brush: Simulation and Experiment

A comparative dynamic Monte Carlo simulation study of polydisperse living polymer brushes, created by surface initiated living polymerization, and conventional polymer monodisperse brush, comprising linear polymer chains, grafted to a planar substrate under good solvent conditions, is presented. The living brush is created by end-monomer (de)polymerization reaction after placing an array of initiators on a grafting plane in contact with a solution of initially non-bonded segments (monomers). At equilibrium, the monomer density profile \phi(z) of the LPB is found to decline as \phi(z) ~ z^{-\alpha} with the distance from the grafting plane z, while the distribution of chain lengths in the brush scales as c(N) ~ N^{-\tau}. The measured values \alpha = 0.64 and \tau = 1.70 are very close to those, predicted within the framework of the Diffusion-Limited Aggregation theory, \alpha = 2/3 and \tau = 7/4. At varying mean degree of polymerization (from L = 28 to L = 170) and effective grafting density (from \sigma_g = 0.0625 to \sigma_g = 1.0), we observe a nearly perfect agreement in the force-distance behavior of the simulated LPB with own experimental data obtained from colloidal probe AFM analysis on PNIPAAm brush and with data obtained by Plunkett et. al., [Langmuir 2006, 22, 4259] from SFA measurements on same polymer

Nanoengineered Injectable Hydrogels for On-Demand and Localized Therapeutic Delivery

“Smart” hydrogels are an emerging class of biomaterials that respond to multiple external stimuli and investigated for a range of biomedical applications, including therapeutic delivery, and regenerative engineering. Stimuli-responsive nanogels based on thermoresponsive polymers such as poly (N-isopropyl acrylamide) (PNIPAM) and magnetic nanoparticles (MNPs), are developed as “smart carriers” for on-demand delivery of therapeutic biomolecules via magneto-thermal activation. However due to their small size and systemic introduction, these PNIPAM/MNPs nanogels result in limited control over long-term, localized therapeutic delivery. Here, we developed an injectable nanoengineered hydrogel loaded with PNIPAM/MNPs for localize on-demand delivery of therapeutics (doxorubicin (DOX)). We have engineered shear-thinning and self-recoverable hydrogels by modulating crosslinking density of our methacrylated gelatin (GelMA) network. PNIPAM/MNPs nano-gels loaded with DOX were entrapped within the GelMA pre-polymer solution prior to crosslinking. The temperature and magnetic field dependent release of loaded DOX was observed from the nano-engineered hydrogels (GelMA/(PNIPAM/MNPs)). The in vitro efficacy of DOX released from injectable nanoengineered hydrogels was investigated using preosteoblast and osteosarcoma cells. Overall, these results demonstrated that the injectable nanoengineered hydrogels can be used for on-demand and localized therapeutic delivery for biomedical applications

Design and development of multiband antennas for unmanned aerial vehicles (UAVs)

Abstract. This thesis aims to design and analyze microstrip patch antennas for unmanned aerial vehicles (UAVs) for Internet of Things (IoT) communication. With the growing need for reliable and efficient communication in UAV, understanding the unique challenges and requirements of antenna design for UAV-based communication systems becomes crucial. During the process of antenna integration onto the UAV body, important attention must be given to vital factors including the availability of mounting space, weight limitations, and radiation parameters. In this study, extensive efforts were made in the design of the antenna to meet the specific requirements for UAV applications. The antenna structure chosen was a microstrip patch antenna with an inset feed technique. The design aimed at optimizing the antenna for multi-band operation, ensuring compatibility with various communication frequencies. Careful considerations were made regarding size, weight, and functionality to ensure the antenna’s suitability for UAV applications. The first part of the thesis introduces the antenna theory, highlighting significant parameters such as radiation pattern, gain, and efficiency, which are crucial for UAV antenna design. The methodology for selecting various parameters is explained, and the radiation pattern and gain of two commercially available antennas were measured in the SATIMO chamber as a benchmark. The fabricated microstrip patch antenna was also tested both with and without the presence of a UAV to examine the impact of the UAV’s body on its performance. The designed antenna demonstrated a semi-omnidirectional pattern at sub-gigahertz frequencies, achieving a gain value exceeding 6 dBi, thereby fulfilling the requirements for UAV applications. The second part of this thesis focused on further advancements in the design process. Efforts were made to improve the antenna’s performance and behavior through various design modifications and optimizations. The design process involved iterative steps, such as adjusting the dimensions and parameters of the antenna to enhance its performance metrics. The results obtained demonstrated notable improvements in terms of radiation patterns with 92 degree of 3 dB angular beamwidth, gain enhancement up to 6.7 dBi, and overall antenna performance. These findings contribute to the body of knowledge in UAV antenna design and highlight the potential for further advancements in this field

Physicochemical and sensory quality changes of surimi from silver carp (Hypophthalmichthys molitrix) in frozen storage at -18ºC

The physicochemical and sensory quality changes of silver carp (Hypophthalmichthys molitrix) surimi were studied during three months at frozen storage (-18ºC). The results showed that with increasing storage time of surimi from silver carp, TVB-N, peroxide value (PV) and expressible moisture increased significantly. TVB-N increased from 10±1 to 16.80±1.4mg%, Peroxide value from zero to 2.76±0.85meqO2/kg and expressible moisture from 4.23±0.13 to 6.32±0.13% during three months at frozen storage. Quality score of sensory evaluation, folding test and biting test were significantly decreased during storage period. Quality score of produced surimi gel decreased from AA to A, C grade and biting test decreased from 8.58±0.98 to 5.25±1.86. The results indicated that in spite of increasing of TVB-N, PV, expressible moisture and decrease of sensory quality score, folding test and biting test of silver carp surimi, the samples were between allowed limits and acceptable after three months at frozen storage

Liquid-phase microextraction of polycyclic aromatic hydrocarbons: A review

Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds comprised of two or more fused benzene rings, which arise from the incomplete combustion of organic materials. These compounds have been of concern as carcinogens and mutagens for the past 50-60 years. Lately, they are also receiving attention as endocrine-disrupting chemicals. Therefore, proper analytical methods are required for sampling and analyzing these compounds. In response to problems associated with the conventional methods like solid-phase extraction (SPE) and liquid-liquid extraction (LLE), many studies have focused on the miniaturization of different sample preparation techniques. In this regard, the use of different types of liquid phase microextraction (LPME) techniques has increased significantly during the recent few decades. LPME techniques are advantageous because they use single-step sample preparation and have shown a greater sensitivity, selectivity, and efficiency than the conventional methods. In addition, these techniques have good potential for automation, to reduce the time and cost of analysis. This review focuses on the most important configurations of LPME including single‐drop microextraction (SDME), hollow-fiber liquid-phase microextraction (HF-LPME), and dispersive liquid-liquid microextraction (DLLME) techniques used for the sampling and determination of PAHs in different samples, along with their cons and pros, as well as their prospects

Identification of boneless parts in silver carp (Hypophthalmicthys molitrix) fillets

The silver carp (Hypophthalmicthys molitrix) comprises about 50% to 85% of the composition of fish species in the polyculture system of warm water species in Iran. However, the difficulty in preparation of this species and the presence of pin bones are among the main reasons to restrict the demand of this species in the domestic markets, particularly in non-coastal province s. The objective of this study was to identify parts with less and/or no bones in silver carp fillets. The shape, size and location of bones found in the flesh were studied by three methods: Enzyme digestion, cooking in hot water and X-ray scanning. Results showed that except vertebral bones and ribs, the thin bones found in different parts of the flesh can be categorized into three groups: Pinshaped, Y shaped and non-regular shaped (several bifurcations). On the basis of density and arrangement of bones, we found that the fillets are made up of three d different layers: External layer mostly of dark muscles and lipids with no bones, middle layer with the highest density of bones and the internal layer which comprises about one third of the depth of fish flesh. The shape and arrangement of the bones in fish tail was significantly different. On the basis of recent findings, the deep part of the back and a narrow band on the upper part of the back are considered as boneless parts in silver carp

On a Kelvin-Voigt Viscoelastic Wave Equation with Strong Delay

An initial-boundary value problem for a viscoelastic wave equation subject to a strong time-localized delay in a Kelvin & Voigt-type material law is considered. Transforming the equation to an abstract Cauchy problem on the extended phase space, a global well-posedness theory is established using the operator semigroup theory both in Sobolev-valued $C^{0}$- and BV-spaces. Under appropriate assumptions on the coefficients, a global exponential decay rate is obtained and the stability region in the parameter space is further explored using the Lyapunov's indirect method. The singular limit $\tau \to 0$ is further studied with the aid of the energy method. Finally, a numerical example from a real-world application in biomechanics is presented.Comment: 34 pages, 4 figures, 1 set of Matlab code

Replacement of dietary fish meal with plant sources in rainbow trout (Oncorhynchus mykiss); effect on growth performance, immune responses, blood indices and disease resistance

The aim of this study was to examine the effects of replacing fish meal with plant sources on growth performance, immune responses, hematological parameters and disease resistance in rainbow trout. In this study, mean of initial body weight of fish was 15±2 g and the experiment was carried out for a period of 60 days. Four experimental diets were formulated to replace 0, 40, 70 and 100% fish meal with plant protein sources (wheat gluten, corn gluten and soybean meal). According to results, higher plant protein inclusions (70 and 100%) resulted in undesirable effects on growth, nutritional indices, serum total immunoglobulin and alternative complement activity (P 0.05). Furthermore, replacement of fish meal with plant sources in all treatments had no significant effects on blood parameters (hematocrit, hemoglobin, white blood cells, hetrophil and lymphocytes count). Finally, no significant differences were observed in fish mortality after 15 days of challenges with Yersinia ruckeri among treatments (P > 0.05)