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Purpose: Cloud Computing is one of the upcoming technologies which has gotten the attention of many researchers and investor. But cloud computing still faces challenges because it is not economical and impractical for research institutions and industries to set up a physical cloud for research and experiments on it (cloud computing). Due to this, the researchers have chosen to test their contributions with simulators. Therefore, the purpose of this study is to perform a survey on existing cloud simulators. Methods: These cloud simulators aid in modeling cloud application through the creation of virtual machine, data Centre, and other things which can be easily added and configured to it in order to provide stress free analysis. Result: Till this present time, many cloud simulators with various features have been proposed and available for use. Novelty: In this paper, a comprehensive study has been performed on major cloud simulators by highlighting their features, strengths, and weakness through analysis. After which comparative analysis was done on the simulation, from the study, none of the simulators have the feature to simulate mobile cloud computing issues. This study has not been published anywhere else.

Aim: The purpose of this short-term randomized trial was to study clinical and radiographic outcomes of Locators and SFI bar attachments used for two -implants immediately loaded by mandibular overdentures Material and method: Twelve edentulous participants (6 males and 6 females) received new maxillary and mandibular dentures and wore them for 3 months to increase muscular control. Two fixtures were installed in the canine regions of the mandible and immediately loaded by mandibular overdentures using Locator (group 1) or SFI bar (group 2) attachments. Plaque index (PI), gingival index (GI), probing depth (PD), stability of the implants (IS), and marginal bone resorption (BL) were measured at base line (insertion), 6 and 12 months later. Results: The implant survival was 91.7% and 100% for Locator and SFI bar groups respectively. PI, PD and BL increased significantly with time in both groups. SFI bar group showed significant higher PI and PD than Locator group after 6 and 12 months. On the other hand, Locator group showed significant higher BL than bar group at 6 and 12 months. No significant difference in GI and IS between observation times or between groups was noted Conclusion: Within limitation of this study, it is concluded that both Locators and SFI bar anchors are recommended for immediately loaded 2 inter-foraminal implants by mandibular overdentures. However, Locators may be favorable regarding improved peri-implant soft tissue conditions and SFI bar may be favorable regarding reduced marginal bone loss around the implants

Mobile learning, also known as m-Learning, is defined as the need and ability to learn through virtual media, such as personal electronic gadgets, social interactions, and content. A mixed method research was conducted using Concurrent mixed method research design among PG students to know their opinion on m-learning. Google forms were used for collecting data. Themes identified were self learning, convenient/practical, new experience and stress free. The study concludes that m-learning can be used as teaching learning tool and students have positive opinion on its use even though the role of teacher is inevitable.Mobile technology is the future for higher education. Keywords: Mobile Learning, Opinion, Mixed Methodology

Aim: The study’s purpose is to find out the factors influencing towards the Purchase of Ready-to-Eat food products among the consumers in Chennai city. Data Sources: The study used both primary and secondary data. The secondary data obtained from the articles, research papers, newspapers, and magazines. The primary data is collected from the consumers of Ready-to-Eat food products in Chennai city. The preliminary data sourced from the consumers through structured questionnaires. Sample size & Method: The study employed the convenience sampling method. Overall, 400 questionnaires were distributed, out of which 392 filled questionnaires were collected from the consumers. Out of 392 questionnaires, seven questionnaires rejected due to inadequate information provided by the consumers. Finally, 385 questionnaires were used for the final analysis. Findings: The study found that the factors namely Convenience, Quality, Mood, Sensory Appeal, Price, and Stress-free significantly influencing the purchase intentions of Ready-to-Eat food products among the consumers in Chennai city.

Soft machines can offer remote-powering mechanisms and mechanical flexibility unmatched by conventional rigid machines. However, the molecular integration of powering and actuation functions in a simple yet versatile format has remained challenging. We achieve this with a semi-crystalline supramolecular metallo-network. The dynamic metallo-bonds offer a flexible mechanism for programming the network anisotropy, which gives rise to stress-free reversible actuation using the crystalline transition as the actuation phase. In addition, the proper choice of metallo-bonds provides suitable photo-thermal capabilities for remote powering without endangering the cyclic actuation stability, despite the supramolecular nature. Based on these principles, we illustrate that the supramolecular network can be programmed into a reptile-style device remotely powered by light. The molecularly integrated dual functionality based on supramolecular metallo-bonds provides an attractive option for the future design of soft machines with sophisticated morphing behaviors yet simple powering mechanisms.

The work carried out studies of the physicomechanical properties of polysulfide sealants of brands of U-30M and UT-31 after thermal, light aging, and the assessment of mushrooms. The data on the resistance of sealants of brands U-30M and UT-31 are investigated and summarized after the impact of accelerated climatic tests and aggressive environments. The optimal time and conditions for the storage of vulcanized sealants in the unattended state and components of sealants in warehouse conditions are determined, as well as the causes of different storage of sealing pastes based on liquid thiocola.

A non-dimensional, axisymmetric, thermal-stress model for a three-layer cylinder with internal heating has been developed. Such a geometry is encountered in an annular target for isotope production. The middle cylinder is the heat generating source with an assumed thermal expansion coefficient that is smaller than that of the other two cylinders enclosing it. Hence, the development of the solution is based on the assumption that interfacial separation occurs at the interface of the middle cylinder and the outer cylinder, while contact is reinforced between the middle cylinder and the inner cylinder. The commercial finite element code Abaqus FEA is used to obtain a numerical model which is validated using the developed analytical solution. The non-dimensional analytical solution has been presented in a simplified, generalized form, and can be applied to either of the cylinders by adjusting a few parameters. The non-dimensional variable groupings allow physical insight into how the stresses and temperature distributions evolve. A detailed solution procedure along with a discussion of the results has been provided.

Rotational Molding is a plastic manufacturing process mainly implemented to produce stress free hollow products. Linear Low Density Polyethylene (LLDPE) is widely preferred as base resin for molding roto molded product, but it displays moderate value in some critical applications where strength is the major criteria. Additives can fill the gap in sustaining the necessary strength needed. In the present work, an attempt has been made to analyze the optimum percentage of coir reinforced with LLDPE for rotational molding technique to provide requisite processability for rotational molding process. Coir in its powder form is mixed at concentrations varying in the range of 3% to 20% with respect to LLDPE. In order to justify the prerequisite of processability for rotational molding, various experiments namely FTIR, MFI, rheology and thermal analysis were conducted. FTIR suggested the range of 5% to 15% wherein the significance of LLDPE and coir peaks can be observed. MFI test supported FTIR result which ended in considering 3% to 12% by weight ratio suitable in terms of flow ability. Rheological and thermal analysis subjecting to shear and heat parameter respectively, confirmed the range of 10 weight percentage of coir or below is suitable in terms of material processability. From the experimental results, it is concluded that 10% or less concentration of coir fiber in LLDPE as an optimum range of blend yielding better processability for rotational molding process.

This study delves with the reflection phenomenon of plane-waves due to incidence of quasi-longitudinal (QL) wave at a semi-infinite structure comprising of pre-stressed piezoelectric-orthotropic su...

Stress-free two-way shape memory polymers (2W-SMPs) capable of reversible shifting between two distinct shapes are versatile platforms for the development of future smart devices. However, it is challenging to prepare stress-free 2W-SMPs with good actuation performance and shape programmability from single-component semicrystalline polymers. Herein, we demonstrate a straightforward and universal strategy for preparing 2W-SMPs through self-nucleated crystallization (SNC) of semicrystalline polymers. SNC enables the formation of two types of crystals in the 2W-SMPs, annealed and primary crystals, which function as the skeleton phase and actuation phase, respectively. We achieved a high reversible actuation strain of 17.6% and a good reprogrammability of the SNC-treated polymer networks. Complex shape transformations were obtained, and smart devices were fabricated from the SNC-treated networks by using a locally designed folding and kirigami structure. The SNC strategy provides a generalized approach to improve the 2W-shape memory behavior of semicrystalline polymers.

Objectives: The aim of this study was to compare marginal bone loss and patient satisfaction with stress free implant bar (SFI bar) and Hader bar used for immediately loaded two-implant retained mandibular overdentures Material and methods: Ten edentulous patients with conventional mandibular dentures due to atrophied mandibular ridge were randomly assigned to 2 groups and received new conventional dentures. After 2-month adaptation period, 2 implants were inserted in the canine regions of the mandible using computer guided surgery and the flapless approach. Implants were connected with Hader bar (group 1) or SFI bar (group 2) and were loaded by mandibular overdentures within 3 days after implant placement. Marginal bone loss was evaluated at baseline, 6, and 12 months later using cone beam CT. Patient satisfaction with conventional dentures and implant overdentures was measured using questionnaire based on visual analogue scale (VAS) Results: Marginal bone loss increased significantly from 6months to 12 months for both groups. Hader bar showed significant higher bone loss than SFI bar after 6 months (p=.001) and 12 months (p

Some people never seem to get stressed out. Understanding their unique resilience could help change all our lives for the better, says Helen Thomson

The aim of this work is to study modern methods of production of corrosion-resistant and fire-resistant stress-free reinforcing bars in the world. Non-stressed reinforcing bars are used as working, structural and assembly reinforcement in conventional building structures, as well as in various types of prestressed structures: from openwork prefabricated to huge monolithic hydraulic structures, therefore, its assortment produced by the domestic metallurgical industry in the range from 5,5 to 40 mm in the nominal diameter of a smooth profile and from 6,0 to 40 mm for a periodic profile. Recently, in the world, much attention is paid to the design and construction of buildings and structures with an improved complex of consumer properties, intended, in particular, for work in corrosive and fire hazardous environments. Such developments are not currently being conducted in Ukraine. In the world and in Europe, to increase corrosion resistance and fire resistance, as well as for the manufacture of seismically resistant reinforcing bars (δmax≥7,5 %), hot-rolled low-alloyed (additionally alloyed with V and Mo) and microalloyed steel grades without the use of heat treatment or cold-deformed (cоld stretched) from hot rolled strip of periodic profile. In GOST 34028-2016 for the countries of the Customs Union, it is clearly stated that for the reinforcement of prefabricated reinforced concrete structures and monolithic reinforced concrete, unstressed reinforcing bars in bars or coils with a nominal diameter of 4,0 to 40 mm are also used for the production of such rolled products, low-carbon and low-alloy steel grades are used, which microalloy V, Nb, Mo or add nitride-forming elements Al, Ti, V, Nb. In this case, either hot rolling or cold deformation or heat treatment in the flow of the rolling mill is used. An alternative way of producing corrosion-resistant and fire-resistant stress-free reinforcing bars in the world is the use of stainless steel as a material. Such profiled reinforcing bars are produced in the range of 3,0 to 50 mm by hot rolling or cold deformation. The use of modern technologies for the production of stainless steel reinforcing bars, starting with the addition of effective and high-quality alloying elements and additives in the production of liquid steel and effective methods of metal pressure treatment, which allows us to guarantee the material saving from corrosion and high temperatures in case of fire. A significant disadvantage of this rolled product is its rather high cost.

In the present work, a new strategy for preparing authentic two-way shape memory polymer was proposed by using a conventional crosslinked polyurethane (PU) containing crystalline poly(ε-caprolactone) (PCL) as the proof-ofconcept material. Lauroyl peroxide (LPO) was added as a chemical crosslinker for inducing secondary crosslinking during the programming. Having been stretched and heat treated without additional ingredients and chemicals, the trained PU showed the desired two-way shape memory effect. The crosslinking network created by LPO was successfully converted into internal stress supplier, which represents the core progress of this research. As the temperature changed, the reversible melting/re-crystallization of the crystalline phases elaborately cooperated with the compressed crosslinking network, leading to the implementation of two-way shape memory effect. Through the optimization of the LPO quality, an average reversible strain of up to ~21% in the direction of stretching was measured. In principle, all semi-crystalline polymers can be imparted with two-way shape memory effect following the above-proposed method. Given the great convenience of material selection, preparation, programming and application, the current research may have opened a new way for the production and usage of the smart materials in practice.

В данной статье приведены результаты теоретических исследований по определению продольного расстояния между стрельчатой лапой и ротационным рыхлителем машины. This article presents the results of theoretical studies to determine the longitudinal distance between the pointed foot and the rotary ripper of the machine.

Complex knee surgeries are technically demanding and high-risk procedures that require diligent thought and preparation from the orthopaedic surgical team (OST). Proper OST preparation for complex knee procedures results in improved patient outcomes, more profitable practices and teams who are generally happier together and work together longer. Prepared and efficient teams are characterised by optimal team composition, communication, checklist utilisation, leadership, reflection and learning. OST preparation must begin days before operating, and complex knee procedures such as meniscus repairs and multiligament reconstruction require especially thorough consideration and preparation both preoperatively and intraoperatively. OST preparation will determine whether complex knee procedures go smoothly and are stress free or are disorganised, hectic and unsafe.

In nonlinear acoustic harmonic generation in solids with stress-free boundaries, such a boundary is known to destructively change the second harmonic generation, and the pulse-echo method is not practically applicable. Focused beams have often been used for fluid nonlinearity and biomechanical imaging in pulse-echo test setups. This paper considers the focused beam fields of linear phased-array transducers to ensure that pulse-echo harmonic generation can be applied to solids with stress-free boundaries. The fundamental and second-harmonic beam fields that are focused and reflected at the stress-free and rigid boundaries are calculated and their properties are investigated in terms of the received average fields. The phase difference between the two second-harmonic components after reflection from the boundary—that is, the reflected and the newly generated second harmonic—is emphasized. The phase difference is used to explain the improved and accumulated second harmonic observed in the simulation results.

2D elastic plane wave diffraction by a stress-free wedge is a canonical problem of interest to researchers in many different fields. To our knowledge, no fully analytical resolution has been found and semi-analytical evaluations of asymptotic approximations have therefore become a common approach. In this paper, a method called the spectral functions method is developed in the aforementioned 2D configuration. This method has the advantage of being valid for wedge angles lower and higher than π. The diffracted displacement field is expressed as an integral in terms of two unknown functions called the spectral functions. These functions are decomposed into two parts: one which can be computed analytically and the other which is approached numerically using a collocation method. The details of the corresponding numerical scheme are given and the method is validated numerically for all wedge angles.

Summary Continuously welded rail track has two critical parameters that affect track stability, namely longitudinal rail stress and lateral resistance of the track structure. Maintaining the stress free temperature of rail plays an important role in managing of rail stress focussing on lateral track stability. Railway companies are focusing on finding an effective means of minimising longitudinal rail forces through management of Stress Free Temperature. In this study, the effectiveness of commercially available rail stress monitors and the rail creep measurement methods to monitor rail stress in railway systems has been investigated. A field investigation of a section of track at Edungalba in Aurizon's heavy haul coal network has enabled observation of Stress Free Temperature through several testing methods. The investigation and analysis has led to insights into track behaviour and stress state. The study concluded that the conventional rail creep method is useful for general indications of track stress condition and follows a similar trend to rail stress monitor data. It was also concluded that accurate measurement of Stress Free Temperature throughout the entire network through installation of rail stress monitor modules may not be a cost-effective solution for the management of rail stress. However, the modules demonstrated an effectiveness to monitor and manage rail stress in targeted problem areas.

Two simple methods are proposed to respectively impart external force-free reversible shape memory effect to commercial polyolefins: ultrahigh molecular weight polyethylene (UHMWPE) and polypropylene (PP). The key issues lie in the utilization of the partially entangled molecular chains of UHMWPE and the medium crystalline phases of PP as the reversible internal stress providers. The acquired reversible shape memory effect further proves to be applicable for assisting repeatedly self-healing of wider cracks. Compared to the conventional approaches, which used to introduce cross-linkages into the target materials, the present ones only need physical treatment, so that the valuable thermoplasticity of polyolefins is retained. This work can be regarded as an example of the concept "physically converting instead of chemically modifying" for the preparation of functional polymeric materials based on market available plastics.

The present work is focused on developing external stress-free two-way triple shape memory polymers (SMPs). Accordingly, a series of innovative approaches are proposed for the material design and preparation. Polyurethane prepolymers carrying crystalline polytetrahydrofuran (PTMEG) and poly(ε-caprolactone) (PCL) as the switching phases are respectively synthesized in advance and then cross-linked to produce the target material. The stepwise method is believed to be conducive to manipulation of the relative contribution of PCL and PTMEG. Moreover, the chain extender, 2-amino-5-(2-hydroxyethyl)-6-methylpyrimidin-4-ol (UPy), is incorporated to establish hydrogen bonds among the macromolecules. By straightforward stretching treatment at different temperatures, the hydrogen bond networks are successfully converted into an internal stress provider, which overcomes the challenge of stress relaxation of the melted low melting temperature polymer (i.e., PTMEG) and increases the efficiency of stress transfer. Meanwhile, the contraction force of the switching phases is tuned to match the internal tensile stress. As a result, the internal stress provider can closely collaborate with melting/recrystallization of the crystalline domains, leading to the repeated multiple shape memory effects. The cross-linked polyurethane is thus able to reversibly morph among three shapes and displays its potentials as soft robot and actuator. The strategy reported here has the advantages of easily accessible raw materials, simple reaction, and facile programing/deprograming/reprograming, so that it possesses wide applicability.

This article deals with the study of three-dimensional vibrations in stress free as well as rigidly fixed, thermally insulated (or isothermal), homogeneous transversely isotropic solid cyli...

A set of standard resistors is a key component of resistance calibration. We have been developing a series of compact superstable standard resistors that meet calibration laboratory demands. In this paper, we describe manufacturing and evaluation of ${1}~{\mathrm {k}\Omega }$ standard resistors. All the resistors elements are made with the “stress free bulk metal foil” technology. We found that all standard resistors show extremely small average drift rates, e.g., smaller than ${10~\mathrm {n}\Omega /(\Omega ~\mathrm {year})}$ and small temperature coefficients typically around $35~{{n}\Omega /(\Omega \, {}^\circ \mathrm {C})}$ at 23 °C. Moreover, continuing the evaluation of drift behavior of $ {1}~{\Omega }$ and $ {10}~{\Omega }$ standard resistors is discussed.

Residual stress is generally evaluated using indentation by comparing the indentation curves of stressed and stress-free states. Here, we suggest a new method that can evaluate surface residual stress without indentation testing on stress-free specimen using stress-independent indentation parameters and an analysis of indentation contact morphology for the stress-free state. We found that several indentation parameters are independent of the stress by Vickers indentation testing on various stress states. The indentation contact morphology can be represented by indentation parameters including stress-independent ones, and by applying the stress-independent parameters obtained from the stressed state to the indentation contact depth function, we can estimate an indentation curve for stress-free state. The estimated curve matches well with the experimental stress-free indentation curve, and it was also confirmed that the applied stress values evaluated by comparing the estimated curve with the stressed indentation curve agree well with the reference values obtained from strain gauge.

This article demonstrates conditions of stress-free deformation of anisotropic FGM interface under thermal loading. Existence of such a deformation is theoretically possible in the case of constant...

Non Destructive Examination (NDE) of industrial structures requires the modeling of specimen geometry echoes generated by the surfaces (entry, backwall …) of inspected blocks. For that purpose, the study of plane wave diffraction by a wedge is of great interest. The work presented here is preliminary research to model the case of an elastic wave diffracted by a wedge in the future, for which there exist various modeling approaches but the numerical aspects have only been developed for wedge angles lower than π. The spectral functions method has previously been introduced to solve the 2D diffraction problem of an immersed elastic wedge for angles lower than π. As a first step, the spectral functions method has been developed here for the diffraction on an acoustic wave by a stress-free wedge, in 2D and for any wedge angle, before studying the elastic wave diffraction from a wedge. In this method, the solution to the diffraction problem is expressed in terms of two unknown functions called the spectral functions. These functions are computed semi-analytically, meaning that they are the sum of two terms. One of them is determined exactly and the other is approached numerically, using a collocation method. A successful numerical validation of the method for all wedge angles is proposed, by comparison with the GTD (Geometrical Theory of Diffraction) solution derived from the exact Sommerfeld integral.

Environmental engineer is concerned with the protection and prevention of the environment and develops the solution to environmental problem. Environmental engineer ensures work place hazards and environmental health and safety related policies and procedure are communicated to employer and employees, ensures the availability of medical surveillance programme in assisting employer and employees in the course of potentially hazards, that can pose immediate danger to health and safety, encouraging conducive environment for stress free conditions in the environment. Consequently, restriction of stress to condition where an environmental demand exceeds the national regulatory capacity of an organism, in particular situations that include unpredictability and uncontrollability also ensuring employees are properly trained for their jobs and environmental health and safety obligation are carried out by everyone involved. Key words: Environment, stress, engineer, health and safety.

Earth’ core is dynamic and always fluctuating by the natural variations in its rotation, creating a massive energy field, known as electromagnetic field (EMF). We are continuously exposed to a wide spectrum of electromagnetic radiation from both natural and artificial sources which have adverse effects on the subtle balance in nature's energy fields. Natural geopathic stressors include geological faults, geomagnetic anomalies, ley lines crossing, radon gas and underground water courses. The affected geographical locations are known as geopathic stress zones as these locations exert negative effects upon health. Geopathic stress can affect all living beings including humans, animals and plants. It is primarily associated with sick building syndrome, potentially lead to physical and mental illnesses. It may also cause pavement distress, as well as frequent machinery broke down. Energy from the subsurface of the earth at specific locations or in a built environment can be detected by using ancient techniques like dowsing, and modern devices such as Spinning Electric Vector Analyzer (SEVA) and gas discharge visualization (GDV) camera, as well as tests like Vegetative Resonance Test (VRT) and Light Interference Technique (LIT). It is important that one's bed or workstation is located on a geopathic stress free zone. There is much that can be done to ameliorate or remove geopathic stress, such as ‘Feng Shui’, Earth acupuncture, and various other modern Western methods. This paper aims to discuss the potential impact of geopathic stress on the living environment and human health.

Good leadership is important for the efficient functioning of an organization. PhD and postdoctoral research is a mentally challenging job, and a good mentor must be able to both treat students with compassion and provide motivation. Coronavirus disease 2019 (COVID-19) has resulted in the decline of the mental health of a large fraction of mentees.

In many instances, the stress situation is simpler than that shown in Fig. 2.6. An example of practical interest is that of a thin plate which is being pulled by forces in the plane of the plate. Figure 5.1 shows a plate of constant thickness, t subjected to axial and shear stresses in the x-directions and y-directions only. These stresses are assumed to be uniformly distributed over the thickness t. The surface normal to the z-axis is stress free.

Continuous welded rails (CWRs) have significantly strengthened the railway tracks by eliminating rail joints between rails. However, as the ambient temperature changes during a year from cold winter to extremely hot summer, high thermal stresses exist and change within the CWR. In some circumstances, it may cause catastrophic disasters such as track buckling, broken rails, and/or derailment. To ensure the CWR track is in stable, longitudinal stress (neutral temperature of CWR) measurement is the most important of the CWR track maintenance. Using the non-destructive method to measure the longitudinal thermal stress in CWR tracks is one of the effort directions for railway track engineers and researches for decades. Within Australia, in the last decade, three types of non-destructive technologies have been approved by the railway infrastructure authorities for neutral temperature measurement. In this paper, the physical theories and technical background of these three technologies are introduced and discussed. In addition, the advantages and limitations of these technologies are discussed based on the experiences that are obtained by using them.

Changing climatic conditions pose a risk to existing transport infrastructures, which are generally built based on historical climate variations. When temperatures exceed built operating conditions, roads may require greater maintenance due to rutting, while railways are susceptible to buckling. We quantify the additional operation and maintenance (O&M) costs to railway and road infrastructures across the 27 Member States of the EU and the United Kingdom (EU + UK) due to the projected rise in extreme heat under different levels of global warming. Our risk assessment integrates an ensemble of climate projections under RCP4.5 and RCP8.5, a high-resolution spatial representation of the rail and road network, and asset valuation and maintenance information derived from multi-country databases, with a road pavement damage model and a railway buckling simulation model. Under a 4 °C global warming level, increased levels of extreme heat in EU + UK cause annual transport O&M costs to rise by €4.8 billion, corresponding to an overall 6.9% rise compared to current values. Mitigating emissions to comply with a 1.5 °C, 2 °C, and 3 °C rise in global average temperature limits the increase to €0.9 billion, €1.3 billion, and €2.8 billion, corresponding to O&M increases of 1.3%, 1.5%, 4.1% respectively. Depending on the value of the stock, replacement costs, and maintenance cycles in a country, the increase in risk can be much stronger. To pre-emptively limit risk, EU + UK road pavement construction standards and railway stress free temperatures should be updated to account for future changes in temperatures.

We show a unique route of colloid gelation where topological percolation generates little mechanical stress., Phase separation often leads to gelation in soft and biomatter. For colloidal suspensions, we have a consensus that gels form by the dynamical arrest of phase separation. In this gelation, percolation of the phase-separated structure occurs before the dynamical arrest, leading to the generation of mechanical stress in the gel network. Here, we find a previously unrecognized type of gelation in dilute colloidal suspensions, in which percolation occurs after the local dynamical arrest, i.e., the formation of mechanically stable, rigid clusters. Thus, topological percolation generates little mechanical stress, and the resulting gel is almost stress-free when formed. We also show that the selection of these two types of gelation (stressed and stress-free) is determined solely by the volume fraction as long as the interaction is short-ranged. This universal classification of gelation of particulate systems may have a substantial impact on material and biological science.

Steady two-dimensional Rayleigh--B\'enard convection between stress-free isothermal boundaries is studied via numerical computations. We explore properties of steady convective rolls with aspect ratios $\pi/5\le\Gamma\le4\pi$, where $\Gamma$ is the width-to-height ratio for a pair of counter-rotating rolls, over eight orders of magnitude in the Rayleigh number, $10^3\le Ra\le10^{11}$, and four orders of magnitude in the Prandtl number, $10^{-2}\le Pr\le10^2$. At large $Ra$ where steady rolls are dynamically unstable, the computed rolls display $Ra \rightarrow \infty$ asymptotic scaling. In this regime, the Nusselt number $Nu$ that measures heat transport scales as $Ra^{1/3}$ uniformly in $Pr$. The prefactor of this scaling depends on $\Gamma$ and is largest at $\Gamma \approx 1.9$. The Reynolds number $Re$ for large-$Ra$ rolls scales as $Pr^{-1} Ra^{2/3}$ with a prefactor that is largest at $\Gamma \approx 4.5$. All of these large-$Ra$ features agree quantitatively with the semi-analytical asymptotic solutions constructed by Chini \& Cox (2009). Convergence of $Nu$ and $Re$ to their asymptotic scalings occurs more slowly when $Pr$ is larger and when $\Gamma$ is smaller.

The aim of this study was to validate an antistress program called “relaxation program” that will be included in the “stress-free” mobile app designed to help Moroccan university students to better manage their psychological stress. The study took place between November 2018 and February 2019 at Faculty of Medicine and Pharmacy of Fez (Morocco). 5th year Medical students were our target population in this study. At first, a cross sectional study was conducted in order to measure students’ baseline stress level by using Perceived Stress Scale 10 (PSS-10) and to assess to students’ acceptability of an antistress mobile application. Based on the results of this study, an interventional part was set up in collaboration with Psychiatric Service of University Hospital Center of Fez (Morocco). In this study, two groups have been created: “group test” who received the “relaxation program” and “group control” who did not receive any type of intervention. The baseline stress level had been qualified “moderate” or “high” for the two groups. The aim of this interventional part was to validate the “relaxation program” by both comparing stress level before and after receiving the “relaxation program” for “group test” and to confirm the stability of stress level for “group control”. 308 students, of whom 61.03% are female, co-operated and accepted to complete the baseline questionnaire. The mean age was 22.35 (SD = 1.22). The premeasurement of stress level showed that 115 (37.5%) of our population had a moderate stress level, and 6.5% had a high stress level. The idea of establishment of an anti-stress mobile application was well accepted by students as 73.37% of them ranged their opinion between “beneficial” and “very beneficial”. The interventional study showed the effectiveness and validity of “relaxation program” on reducing the stress level for “group test” by using the statistical t-test (Mean pre-measurement =26.14 vs. Mean post-measurement= 18.54; p =.000). This study highlights the statistical and clinical validity of “relaxation program”. Future studies will be planned in order to develop the adaptive design to this anti-stress program in order to incorporate it in the “stressfree” mobile application.

The multiplicative decomposition model is widely employed for predicting residual stresses and morphologies of biological tissues due to growth. However, it relies on the assumption that the tissue is initially in a stress-free state, which conflicts with the observations that any growth state of a biological tissue is under a significant level of residual stresses that helps to maintain its ideal mechanical conditions. Here, we propose a modified multiplicative decomposition model in which the initial state (or reference configuration) of a biological tissue is endowed with a residual stress instead of being stress-free.Releasing theoretically the initial residual stress, the initially stressed state is first transmitted into a virtual stress-free state, thus resulting in an initial elastic deformation. The initial virtual stress-free state subsequently grows to another counterpart with a growth deformation, and the latter is further integrated into its natural configuration of a real tissue with an excessive elastic deformation that ensures tissue compatibility. With this decomposition, the total deformation arising during growth may be expressed as the product of elastic deformation, growth deformation and initial elastic deformation, while the corresponding free energy density should depend on the initial residual stress and the total deformation. Three key issues including the explicit expression of the free energy density, the predetermination of the initial elastic deformation, and the initial residual stress are addressed.Finally, we consider a tubular organ as a representative example to demonstrate the effects of the proposed initial residual stress on stress distribution and on shape formation through an incremental stability analysis. Our results suggest that the initial residual stress exerts a major influence on the growth stress and the morphology of biological tissues. The model bridges the gap between any two growth states of a biological tissue that is endowed with a certain level of residual stresses. (C) 2018 Elsevier Ltd. All rights reserved. This work was supported by the National Natural Science Foundation of China through grant Nos. 11621062 and 11772295, and was also partly supported by the Fundamental Research Funds for the Central Universities 2016XZZX001-05. peer-reviewed 2020-05-19

This paper attempts to show the importance of elicitation in language classrooms for teachers and learners as well. Elicitation helps in motivating English language learners. Most of the teachers think that applying elicitation in language classrooms promotes interest among students, set a stress free environment, and increases students' participation. However, all teachers do not share the same attitude towards elicitation because of some drawbacks. Therefore, this paper discusses the effectiveness of using elicitation as a powerful diagnostic tool for actively involving learners in the language classrooms, the merits and demerits of elicitation, necessity of language teachers to focus on this technique in a skilled way that helps the learners develop their English language skills, and some factors affecting the teachers in using the elicitation techniques. For this purpose, a mini-research was conducted where 30 undergraduate students and 15 non-native language teachers of a university in Saudi Arabia were chosen as participants in carrying out the study. This paper also offers some suggestions for both experienced and novice teachers to focus on some criteria for applying elicitation techniques for motivating students and having variety in the language class.

A set of marking symbols had been devised by staff to be used during English lessons. These had been designed and produced to enable all pupils to become more involved with self-assessment. By continuing to promote and develop a consistent use of marking symbols, the intended outcome was to successfully reduce the amount of time teachers spent marking, without this having a negative impact on children’s progress. Undoubtedly the use of marking symbols has played a significant role in helping reduce teacher marking workload in English. More planned peer assessment opportunities would assist pupils in becoming more resilient and less dependent on teachers. Teacher intervention, during the project, was noticeably reduced as pupils became more adept and proficient in using marking symbols to progress their learning. Regular opportunities were also provided for pupils to participate in peer assessment exercises. This was intended to further develop children confidence in the assessment process.

We evaluated the Coulombic interactions of the lithium cation in the separator membrane of lithium secondary batteries in terms of the morphological factors of the separator membrane and the solvat...