The Ball-Box Theorem for a Class of Corank 1 Non-differentiable Tangent Subbundles

We show that an analogue of the ball-box theorem holds true for a class of corank 1, non-differentiable tangent subbundles that satisfy a geometric condition. We also we give examples of such bundles and give an application to dynamical systems.     

Surface modification of superabsorbing hydrogels through a feasible esterification reaction: Toward tunable superabsorbent for hygienic applications

Improved superabsorbent polymers (SAPs) were prepared by feasible esterification reactions to prohibit gel blockage and develop swollen gel strength leading to enhanced saline absorbency under load (AUL). Thus, water–dimethylsulfoxide solutions containing benzyl chloride and 1,2-dichloroethane were used to modify SAP particle surface through tetramethylguanidine-promoted reactions. Attenuated total reflection-Fourier transform infrared spectroscopy was used to verify the modification. Influence of the modification reaction variables on free swelling (in water and saline), AUL, absorption rate, contact angle, water retention capability, gel blockage prohibition, gel content, and rheological properties were investigated. This modification approach was considered as a good candidate to scale up the production of SAPs for hygienic applications.     

Nonlinear membrane model for large amplitude vibration of single layer graphene sheets

The nonlinear vibrational properties of single layer graphene sheets (SLGSs) are investigated using a membrane model. The nonlinear equation of motion is considered for the SLGSs by including the effects of stretching due to large amplitudes. The equation of motion is numerically solved utilizing the finite difference method for SLGSs with different initial and boundary conditions, sizes and pretensions. It is concluded that the nonlinear fundamental frequency of SLGSs increases by increasing the pretension and initial velocity. In addition, it is observed that an increase in the pretension weakens the effects of the initial velocity on the fundamental frequency, such that the fundamental frequency approximately becomes independent of the initial velocity. This is an important feature of the vibrating systems consisting of SLGSs which are used in the nano-electromechanical systems (NEMS), where resonators with a specific fundamental frequency and independent of the initial velocity are of interest.     

Three‐Dimensional Database Mining Identifies a Unique Chemotype that Unites Structurally Diverse Botulinum Neurotoxin Serotype A Inhibitors in a Three‐Zone Pharmacophore

A search query consisting of two aromatic centers and two cationic centers was defined based on previously identified small molecule inhibitors of the botulinum neurotoxin serotype A light chain (BoNT/A LC) and used to mine the National Cancer Institute Open Repository. Ten small molecule hits were identified, and upon testing, three demonstrated inhibitory activity. Of these, one was structurally unique, possessing a rigid diazachrysene scaffold. The steric limitations of the diazachrysene imposed a separation between the overlaps of previously identified inhibitors, revealing an extended binding mode. As a result, the pharmacophore for BoNT/A LC inhibition has been modified to encompass three zones. To demonstrate the utility of this model, a novel three‐zone inhibitor was mined and its activity was confirmed.     

A modified algorithm to improve security and performance of AODV protocol against black hole attack

Ad Hoc network is a temporal network which is managed by autonomous nodes which have the ability to communicate with each other without having fixed network infrastructure or any central base station. Due to some reasons such as dynamic changes of the network topology, trusting the nodes to each other, lack of fixed substructure for the analysis of nodes’ behaviours and loss of specific offensive lines, this type of networks is not supportive against malicious nodes’ attacks. One of these attacks is black hole attack. In this attack, the malicious nodes absorb data packets and destroy them. Thus, it is essential to present an algorithm against the black hole attacks. This article suggests a new algorithm which enhances the security of AODV routing protocol to encounter the black hole attacks. This algorithm tries to identify malicious nodes according to nodes’ behaviours in an Ad Hoc network and delete them from routing. The suggested algorithm is simulated by NS2. The simulation results show some improvements in end-to-end delay and packet delivery rate in the suggested algorithm.     

Recognition of defensive factors in the architectural heritage of Iran's organic ancient shelters

In ancient Iran, in addition to defensive elements such as castles, fortresses, and fortifications, there were underground cities called dastkand. These cities had a shelter-protection function and provided safe space to protect residents when enemies attacked. In the scope of dastkand architectural studies, form typology, land-use typology, and provision of thermal comfort have been investigated in various studies but there is no study on dastkand defensive architecture, which is the main purpose of the present research. The research method is a mixed method (qualitative-quantitative). The required data are collected through a survey and then, analyzed using factor analysis in R method. The statistical population includes Iranian architectural heritage specialists and the sample size is estimated to be 165 persons. Sampling adequacy is confirmed based on the results of KMO test. The samples are selected using a non-probability sampling method. The obtained results indicate that ten factors have been effective in the architecture of Iran's ancient organic shelters. In order from largest to smallest coefficient of variance, the factors include collective defense, multi-layered defense, environmental camouflage, path control, self-sufficiency, secret passage, sustainable architecture, residential values, covert surveillance, and cluster development.     

Multiobjective optimal placement of active tendons to control irregular multistory buildings with soil–structure interaction

In recent decades, many researchers have conducted research studies on structural control to improve the safety and serviceability of high‐rise buildings against earthquakes and strong winds. On the other hand, applying active control systems and controlling strategies in buildings are costly process, and it is necessary to reduce the number of controllers. In this paper, a multiobjective genetic algorithm is proposed to optimize the placement of active tendons in a 2D shear frame and a 3D irregular building considering soil–structure interaction effect to reduce active control cost and response of structures at the same time. For multiobjective optimization, multiobjective genetic algorithm of the MATLAB toolbox is used to find a set of Pareto optimal solutions for a multiobjective minimization. The results indicate that the method is capable of finding the number and location of the required active tendons in both 2D shear frame and 3D irregular building with 10 and 20 stories while the base shear of structure is minimized. The specific advantage of the employed algorithms is to reduce the number of mounted active tendons approximately by 50%.     

Biosorption of anionic dyes from aqueous solutions using a novel magnetic nanocomposite adsorbent based on rice husk ash

This study investigated the potential use of an agricultural waste, rice husk ash, for the removal of methyl orange. The adsorbent was prepared via a simple one-pot synthesis of magnetic iron oxide nanoparticles (MIONs). The prepared magnetic nanocomposites were characterized using Fourier transform infrared, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometer techniques. Bach adsorption experiments were carried out to evaluate the effects of initial dye concentration, pH and contact time as well as MION content on adsorption capacity. The mechanism of dye adsorption was well fitted to a pseudo-second-order kinetic model. Moreover, the equilibrium data fitted well with the Langmuir isotherm model.     

Exploration–exploitation trade-off features a saltatory search behaviour

Searching experiments conducted in different virtual environments over a gender-balanced group of people revealed a gender irrelevant scale-free spread of searching activity on large spatio-temporal scales. We have suggested and solved analytically a simple statistical model of the coherent-noise type describing the exploration–exploitation trade-off in humans (‘should I stay’ or ‘should I go’). The model exhibits a variety of saltatory behaviours, ranging from Lévy flights occurring under uncertainty to Brownian walks performed by a treasure hunter confident of the eventual success.