High-performance natural rubber composites based on lignocellulosic fillers

Ce travail est consacré au développement de biocomposites de caoutchouc naturel (NR) performants pour produire des composites ayant des propriétés similaires aux formulations conventionnelles à base de noir de carbone (CB). Le projet est divisé en deux parties principales selon les types de charges: les charges lignocellulosiques de taille macro et la nanocellulose. Dans un premier temps, le remplacement du CB par de la lignine et de la cellulose (avec et sans modification) est étudié. Les résultats montrent que la lignine et la cellulose ont leurs propres avantages et limites, mais le remplacement partiel du CB par les deux macro-biocharges peut fournir de meilleures propriétés mécaniques et dynamiques par rapport au CB seul. Néanmoins, des propriétés améliorées sont également obtenues après une modification de surface de la cellulose par de l'anhydride maléique greffé sur du polyisoprène (MAPI). Cependant, il n'est pas possible de remplacer complètement le CB par ces charges en raison des fortes interactions entre les charges. Ensuite, l'effet de la nanocellulose sur le renforcement du NR est étudié. Ce travail comprend également un système de renforcement hybride à base de nanocellulose et de nanotubes de carbone (CNT) qui montre la formation d'un réseau conducteur 3D solide à l'intérieur de la matrice de caoutchouc. La présence de ce réseau conduit à d'excellentes propriétés (propriétés mécaniques dynamiques et conductivité thermique) qui peuvent être facilement contrôlées en ajustant la teneur en charges. Enfin, un nouveau système hybride contenant de la lignine et de la nanocellulose a été développé pour renforcer le NR. Dans ce cas, une concentration élevée (40 parties pour cent de caoutchouc, phr) de lignine est utilisée comme biocharge non-renforçante pour réduire les coûts et augmenter la durabilité, tandis que la nanocellulose est ajoutée pour renforcer ces biocomposites NR. On constate que l'ajout de 7,5 phr de nanocellulose aux composés lignine/NR (contenant 40 phr de lignine) augmente la teneur en caoutchouc lié (37%), la résistance à la traction (36%) et le module à 100 % de déformation (101%), tout en diminuant le temps de durcissement (14%) et le facteur de perte (55% à 10% de déformation). Malgré sa biodégradabilité et sa durabilité, le bionanocomposite nanocellulose/lignine/NR présente des propriétés mécaniques similaires et même de meilleures propriétés mécaniques dynamiques (53% à 10% de déformation) que les composites NR conventionnels renforcés avec du CB seul.This work is devoted to the development of high-performance natural rubber (NR) biocomposites to produce composites having similar properties as conventional formulations based on carbon black (CB). The project is divided into two main parts depending on the types of fillers: macro-sized lignocellulosic fillers and nanocellulose. Firstly, the effect of replacing CB by lignin and cellulose (with and without modification) is studied. The results show that both lignin and cellulose have their own advantages and limitations, but partial replacement of CB with both macro-biofillers can provide better mechanical and dynamic mechanical properties compared to CB alone. Nevertheless, improved properties are also obtained after surface modification of the cellulose with maleic anhydride grafted to polyisoprene (MAPI). However, it is not possible to completely replace CB with these fillers due to strong filler-filler interactions. Then, the effect of nanocellulose on NR reinforcement is studied. This work also includes a hybrid reinforcing system based on nanocellulose and carbon nanotube (CNT) which is showing the formation of a strong 3D conductive network inside the rubber matrix. The presence of this network leads to excellent properties (mechanical and dynamic properties, and thermal conductivity), which can be easily controlled by tuning the fillers content ratio. Finally, a novel hybrid system containing lignin and nanocellulose is developed to reinforce NR. In this case, a high concentration (40 parts per hundred rubber, phr) of lignin is used as a non-reinforcing biofiller to reduce the costs and increase the sustainability, while nanocellulose is added to reinforce these NR biocomposites. It was found that adding 7.5 phr of nanocellulose to the lignin/NR compounds (containing 40 phr lignin) increased the bound rubber content (37%), tensile strength (36%) and modulus at 100% strain (101%), while decreasing the curing time (14%) and loss factor (55% at 10% strain). Despite its biodegradability and sustainability, the nanocellulose/lignin/NR bionanocomposite exhibits similar mechanical properties and even better dynamic mechanical properties (53% at 10% strain) than conventional NR composites reinforced with CB alone

UTJECAJ RAZLIČITIH DOZA SINTETIČKOG HORMONA LHRH-A2, NA RAZINE SPOLNIH HORMONA U SERUMU, POSTOTAK USPJEŠNOSTI OVULACIJE I STOPE VALJENJA JAJA PERZIJSKE JESETRE, Acipenser persicus

Acipenser persicus is one of the economically valuable fishes in the Caspian Sea. Due to the economical and cultural importance of sturgeons in the world, understanding of sturgeon reproduction is necessary for successful management of their populations in aquaculture and nature. To improve the culture methods and to facilitate captive breeding programs to support restocking, it is necessary to understand the changes in steroid hormones during artificial reproduction. The administration of sturgeon luteinizing hormone - releasing hormone analogue (LHRH-A2) induces changes in serum sex steroid levels. To study the effects of different doses of LHRH-A2 hormone on induction of final maturation and ovulation of Persian sturgeon, 18 maturating females and 18 maturating males were used. All brooders were injected with LHRH-A2 in dosages of 4, 6 and 8 μg kg-1. In this study, LHRH-A2 successfully induced final maturation and ovulation in females, and the highest percentage of ovulated females was observed in the groups treated with dose of 4 μg kg-1 LHRH-A2. There were significant differences in serum cortisol (C), testosterone (T) and Gonado-tropin hormone (GTHII) concentrations at tested dosages. In hormonal treatment groups, the highest hatching rate was observed in the groups receiving 4 μg kg-1 LHRH-A2. Finally, the LHRH-A2 in dose of 4 μg kg-1 is effective in stimulating oocyte maturation and ovulation in Persian sturgeon.Acipenser persicus (Acipenseridae) jedna je od ekonomski važnijih vrsta riba u Kaspijskom moru. Poznavanje reproduktivnih karakteristika jesetre je važno zbog uspješnog upravljanja njihovim populacijama u akvakulturi te njihove ekonomske i kulturne važnosti u svijetu. Razumijevanje razina steroidnih hormona i njihovih promjena u serumu tijekom umjetne oplodnje pomaže poboljšanju kvalitete nasadnih metoda te olakšava izvedbu programa razmnožavanja u zatočeništvu u svrhu potpore poribljavanja. Primjenom sintetičkog luteinizirajućeg hormona jesetre - oslobađajućeg analognog hormona (LHRH-A2) - induciraju se promjene u razinama spolnih steroida u serumu. Za proučavanje učinka različitih doza hormona LHRH-A2 na izazivanje konačnog sazrijevanja i ovulacije Perzijske jesetre, korišteno je 18 odraslih ženki i 18 odraslih mužjaka. Sve muške i ženske spolno zrele jedinke su inducirane s LHRH-A2 u dozama od 4, 6 i 8 μg kg-1. U ovoj studiji primjenom LHRH-A2 uspješno je inducirano sazrijevanje gonada i ovulacije u ženki, dok je najveći postotak ovuliranih ženki uočen u skupini tretiranoj dozom od 4 μg kg-1 LHRH-A2. Postoje značajne razlike u koncentracijama kortizola (C), testosterona (T) i gonadotropina (GTHII) u serumu ispitivanih doza hormona. Najveći postotak valjenja uočen je u skupinama riba koje su primale 4 μg kg-1 LHRHA 2. U dozi od 4 μg kg-1, LHRH-A2 je učinkovit pri poticanju sazrijevanja oocita te ovulacije Perzijske jesetre

Evaluating impacts of unexpected earning on precision of profit estimation

Precision in earning report has always been a concern among investors, and when there are some negative adjustments on earning, investor may find it challenging to decide whether they should hold or sell their shares. This paper studies the impact of earning precision and unexpected earning adjustments on firms whose share are listed on Tehran Stock Exchange. The proposed study of this paper considers three hypotheses including whether earning precision has negative relationship with unexpected profit, whether it has a negative with unexpected decline in profit and finally, whether, in prediction on negative news compared with positive news, there is a negative relationship between stronger earnings forecast and precision of earning forecast. The study gathers the necessary data from official news released for some firms whose shares were active over the period 2003-2012. The study uses two regression models and the results of regression analysis have confirmed all hypotheses of this survey

A Learning-based Stochastic MPC Design for Cooperative Adaptive Cruise Control to Handle Interfering Vehicles

Vehicle to Vehicle (V2V) communication has a great potential to improve reaction accuracy of different driver assistance systems in critical driving situations. Cooperative Adaptive Cruise Control (CACC), which is an automated application, provides drivers with extra benefits such as traffic throughput maximization and collision avoidance. CACC systems must be designed in a way that are sufficiently robust against all special maneuvers such as cutting-into the CACC platoons by interfering vehicles or hard braking by leading cars. To address this problem, a Neural- Network (NN)-based cut-in detection and trajectory prediction scheme is proposed in the first part of this paper. Next, a probabilistic framework is developed in which the cut-in probability is calculated based on the output of the mentioned cut-in prediction block. Finally, a specific Stochastic Model Predictive Controller (SMPC) is designed which incorporates this cut-in probability to enhance its reaction against the detected dangerous cut-in maneuver. The overall system is implemented and its performance is evaluated using realistic driving scenarios from Safety Pilot Model Deployment (SPMD).Comment: 10 pages, Submitted as a journal paper at T-I

Bone-marrow-derived Mesenchymal Stem Cell-Based Therapy for Wound Healing

Abstract Skin is the largest organ in the human and animal body and serves as the first line of defense against the external environment. The present study aimed to summarize the mechanisms underlying the effect of MSCs on wound healing and describe the latest strategies to enhance their therapeutic efficacy. Wounds caused by cuts, abrasions, or burns can disrupt the skin integrity, leading to severe consequences, such as infections, scarring, and reduced mobility. Therefore, effective wound healing therapies are essential to reduce the risk of complications and improve the quality of life for patients. In recent years, mesenchymal stem cells (MSCs) have emerged as promising therapy for wound healing due to their unique properties. The MSCs are found in various tissues, including the bone marrow, and can differentiate into multiple cell types, including skin cells. Additionally, MSCs can secrete substances with anti-inflammatory, anti-fibrotic, and pro-angiogenic properties, which play a critical role in the wound healing process. The MSCs can release these substances as soluble molecules, such as growth factors and cytokines, or enclosed within membrane vesicles like microparticles and exosomes. By releasing these substances, MSCs can reduce inflammation, prevent excessive scarring, and promote the growth of new blood vessels, which are crucial for effective wound healing. The MSC-based therapies have indicated promising results for wound healing. However, the optimal dosage, route of administration, and timing of MSC-based treatments for wound healing applications are yet to be determined. Despite the great potential of bone marrow-derived MSCs to improve the healing process of damaged skin caused by wounds and burns, more research is needed to fully understand how MSCs enhance wound healing and optimize their use in clinical settings. https://jlar.rovedar.com/index.php/JLAR/article/view/

A Learning-Based Framework for Two-Dimensional Vehicle Maneuver Prediction over V2V Networks

Situational awareness in vehicular networks could be substantially improved utilizing reliable trajectory prediction methods. More precise situational awareness, in turn, results in notably better performance of critical safety applications, such as Forward Collision Warning (FCW), as well as comfort applications like Cooperative Adaptive Cruise Control (CACC). Therefore, vehicle trajectory prediction problem needs to be deeply investigated in order to come up with an end to end framework with enough precision required by the safety applications' controllers. This problem has been tackled in the literature using different methods. However, machine learning, which is a promising and emerging field with remarkable potential for time series prediction, has not been explored enough for this purpose. In this paper, a two-layer neural network-based system is developed which predicts the future values of vehicle parameters, such as velocity, acceleration, and yaw rate, in the first layer and then predicts the two-dimensional, i.e. longitudinal and lateral, trajectory points based on the first layer's outputs. The performance of the proposed framework has been evaluated in realistic cut-in scenarios from Safety Pilot Model Deployment (SPMD) dataset and the results show a noticeable improvement in the prediction accuracy in comparison with the kinematics model which is the dominant employed model by the automotive industry. Both ideal and nonideal communication circumstances have been investigated for our system evaluation. For non-ideal case, an estimation step is included in the framework before the parameter prediction block to handle the drawbacks of packet drops or sensor failures and reconstruct the time series of vehicle parameters at a desirable frequency

Multi-Hop Wireless Optical Backhauling for LiFi Attocell Networks: Bandwidth Scheduling and Power Control

The backhaul of hundreds of light fidelity (LiFi) base stations (BSs) constitutes a major challenge. Indoor wireless optical backhauling is a novel approach whereby the interconnections between adjacent LiFi BSs are provided by way of directed line-of-sight (LOS) wireless infrared (IR) links. Building on the aforesaid approach, this paper presents the top-down design of a multi-hop wireless backhaul configuration for multi-tier optical attocell networks by proposing the novel idea of super cells. Such cells incorporate multiple clusters of attocells that are connected to the core network via a single gateway based on multi-hop decode-and-forward (DF) relaying. Consequently, new challenges arise for managing the bandwidth and power resources of the bottleneck backhaul. By putting forward user-based bandwidth scheduling (UBS) and cell-based bandwidth scheduling (CBS) policies, the system-level modeling and analysis of the end-to-end multi-user sum rate is elaborated. In addition, optimal bandwidth scheduling under both UBS and CBS policies are formulated as constrained convex optimization problems, which are solved by using the projected subgradient method. Furthermore, the transmission power of the backhaul system is opportunistically reduced by way of an innovative fixed power control (FPC) strategy. The notion of backhaul bottleneck occurrence (BBO) is introduced. An accurate approximate expression of the probability of BBO is derived, and then verified using Monte Carlo simulations. Several insights are provided into the offered gains of the proposed schemes through extensive computer simulations, by studying different aspects of the performance of super cells including the average sum rate, the BBO probability and the backhaul power efficiency (PE).Comment: 36 pages, 21 figures, 1 tabl

Teaching Courses in Macroeconomics and Monetary Policy with Bloomberg Analytics

In this article, the authors illustrate the use of Bloomberg for analyzing topics in macroeconomics and monetary policy in economics and finance courses. The hands-on experience that students gain from such a course has many benefits, including deeper learning and clearer understanding of data. The authors describe goals and learning objectives, then compare Bloomberg with Federal Reserve Economic Data (FRED). In addition, they provide examples of how to use Bloomberg in the classroom, describe how to have students perform sector analysis, show how Bloomberg tools are useful for analyzing monetary policy, discuss how to use Bloomberg to analyze the financial sector, and illustrate the platform’s use in a case study

Wireless optical backhauling for optical attocell networks

The backhaul of tens and hundreds of light fidelity (LiFi)-enabled luminaires constitutes a major challenge. The problem of backhauling for optical attocell networks has been approached by a number of wired solutions such as in-building power line communication (PLC), Ethernet and optical fiber. In this work, an alternative solution is proposed based on wireless optical communication in visible light (VL) and infrared (IR) bands. The proposed solution is thoroughly elaborated using a system level methodology. For a multi-user optical attocell network based on direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM) and decode-and-forward (DF) relaying, detailed modeling and analysis of signal-to-interference-plus- noise (SINR) and end-to-end sum rate are presented, taking into account the effects of inter-backhaul and backhaul-to-access interferences. Inspired by concepts developed for radio frequency (RF) cellular networks, full-reuse visible light (FR-VL) and in-band visible light (IB-VL) bandwidth allocation policies are proposed to realize backhauling in the VL band. The transmission power is opportunistically minimized to enhance the backhaul power efficiency. For a two-tier FR-VL network, there is a technological challenge due to the limited capacity of the bottleneck backhaul link. The IR band is employed to add an extra degree of freedom for the backhaul capacity. For the IR backhaul system, a power-bandwidth tradeoff formulation is presented and closed form analytical expressions are derived for the corresponding power control coefficients. The sum rate performance of the network is studied using extensive Monte Carlo simulations. In addition, the effect of imperfect alignment in backhaul links is studied by using Monte Carlo simulation techniques. The emission semi-angle of backhaul LEDs is identified as a determining factor for the network performance. With the assumption that the access and backhaul systems share the same propagation medium, a large semi-angle of backhaul LEDs results in a substantial degradation in performance especially under FR-VL backhauling. However, it is shown both theoretically and by simulations that by choosing a sufficiently small semi-angle value, the adverse effect of the backhaul interference is entirely eliminated. By employing a narrow light beam in the back-haul system, the application of wireless optical backhauling is extended to multi-tier optical attocell networks. As a result of multi-hop backhauling with a tree topology, new challenges arise concerning optimal scheduling of finite bandwidth and power resources of the bottleneck backhaul link, i.e., optimal bandwidth sharing and opportunistic power minimization. To tackle the former challenge, optimal user-based and cell-based scheduling algorithms are developed. The latter challenge is addressed by introducing novel adaptive power control (APC) and fixed power control (FPC) schemes. The proposed bandwidth scheduling policies and power control schemes are supported by an analysis of their corresponding power control coefficients. Furthermore, another possible application of wireless optical backhauling for indoor networks is in downlink base station (BS) cooperation. More specifically, novel cooperative transmission schemes of non-orthogonal DF (NDF) and joint transmission with DF (JDF) in conjunction with fractional frequency reuse (FFR) partitioning are proposed for an optical attocell downlink. Their performance gains over baseline scenarios are assessed using Monte Carlo simulations