Non-uniform Euler-Bernoulli beams under a single moving oscillator: An approximate analytical solution in time domain

Dynamic responses of simply supported non-uniform beams traversed by a moving oscillator are analysed in this paper. An approximate analytical method based on Rayleigh-Ritz (R-R) formulation is developed. The fundamental approximate mode obtained from R-R method is used in the present formulation to determine the responses of the beam and the oscillator. Effects of surface irregularities on the displacement and acceleration responses of the beam and the vehicle are also analysed. The results are compared with those obtained using Finite element method (FEM). A numerical example is provided to illustrate the validity of the present method which shows that the proposed method is simple, computationally more efficient compared to FEM and gives fairly good results. Though the single-mode approach used in the present paper is a classical one and numerous studies on the responses of uniform beams under moving loads have been reported in the past, its application to non-uniform beams (for which there does not exist any closed form expression for mode shapes) under a moving load, especially a moving oscillator, is presented for the first time.     

Effect of lysine incorporation,annealing and heat moisture treatment alone and in combination on the physico-chemical,retrogradation, rheological properties and in vitro digestibility of kithul (Caryota urens L.) starch

Physico-chemical, retrogradation, rheological properties and in vitro digestibility of lysine incorporated kithul starch modified by annealing, heat moisture treatment and its combinations were studied. LS-AHMT (annealed-heat moisture treated lysine incorporated kithul starch) exhibited lowest amylose leaching. LS-AHMT showed significantly (P ≤ 0.05) higher relative crystallinity. LS-ANS (annealed lysine incorporated kithul starch), LS-HMT (heat moisture treated lysine incorporated kithul starch) and LS-AHMT formed more weak gel by the effect of annealing, heat moisture treatment and its combination. LS-AHMT showed lowest pasting viscosities, G′ and G″ values among the modified kithul starch, which indicates its lower retrogradation properties. In vitro digestibility of kithul starch decreased after modifications and LS-ANS, LS-HMT and LS-AHMT showed significantly higher resistant starch content. The current study showed that annealing, heat moisture treatment and its combination on NS-LS (lysine incorporated kithul starch) effectively modified kithul starch properties.     

Polymer induced structures in cetylpyridinium chloride–octanol micellar system

The effect of octanol on the interaction of polyethylene glycol (PEG) and cetylpyridinium chloride (CPC) were investigated by viscosity, conductivity, differential scanning calorimetry (DCS), polarizing microscopy, Fourier transform infrared spectroscopy (FTIR) and rheology analysis. The aggregation of polymer-surfactant micelles takes place at a surfactant concentration higher than the critical micelle concentration. The long chain aliphatic alcohol (n-octanol) induced rapid structural transformation in the mixed micellar system by unusual cooperative micellization. The rheological behavior of the viscoelastic system reveals the presence of giant aggregates in this system. The lyotropic nature of the giant aggregates was monitored by DSC and polarizing microscopic studies, and which was confirmed by cryo-TEM.     

Chitin and chitosan in selected biomedical applications

Chitin (CT), the well-known natural biopolymer and chitosan (CS) (bio-based or “artificial polymer”) are non-toxic, biodegradable and biocompatible in nature. The advantages of these biomaterials are such that, they can be easily processed into different forms such as membranes, sponges, gels, scaffolds, microparticles, nanoparticles and nanofibers for a variety of biomedical applications such as drug delivery, gene therapy, tissue engineering and wound healing. Present review focuses on the diverse applications of CT and CS membranes and scaffolds for drug delivery, tissue engineering and targeted regenerative medicine. The chitinous scaffolds of marine sponges’ origin are discussed here for the first time. These CT based scaffolds obtained from Porifera possess remarkable and unique properties such as hydration, interconnected channels and diverse structural architecture. This review will provide a brief overview of CT and CS membranes and scaffolds toward different kinds of delivery applications such as anticancer drug delivery, osteogenic drug delivery, and growth factor delivery, because of their inimitable release behavior, degradation profile, mucoadhesive nature, etc. The review also provides an overview of the key features of CT and CS membranes and scaffolds such as their biodegradability, cytocompatibility and mechanical properties toward applications in tissue engineering and wound healing.     

Diethyl ether as an ignition improver for biogas homogeneous charge compression ignition (HCCI) operation - An experimental investigation

This paper deals with experimental investigations of a homogeneous charge compression ignition (HCCI) engine using biogas as a primary fuel and diethyl ether (DEE) as an ignition improver. The biogas is inducted and DEE is injected into a single-cylinder engine. For each load condition, best brake thermal efficiency DEE flow rate is determined. The results obtained in this study are also compared with those of the available biogas-diesel dual-fuel and biogas spark ignition (SI) modes. From the results, it is found that biogas-DEE HCCI mode shows wider operating load range and higher brake thermal efficiency (BTE) at all loads as compared to those of biogas-diesel dual-fuel and biogas SI modes. In HCCI mode, at 4.52 bar BMEP, as compared to dual-fuel and SI modes, BTE shows an improvement of about 3.48 and 9.21% respectively. Also, nitric oxide (NO) and smoke emissions are extremely low, and carbon monoxide (CO) emission is below 0.4% by volume at best brake thermal efficiency points. Also, in general, in HCCI mode, hydrocarbon (HC) emissions are lower than that of biogas SI mode. Therefore, it is beneficial to use biogas-DEE HCCI mode while using biogas in internal combustion engines.     

Optical asymmetric cryptosystem based on photon counting and phase-truncated Fresnel transforms

We propose a novel optical asymmetric cryptosystem combining the photon counting imaging with phase-truncated Fresnel transform, which can be used for complete information retrieval and authentication verification. The proposed combination overcomes the weakness of photon counting-based double random phase-encoding scheme. For retrieval of original image for authentication, the reverse process of phase truncation approach is followed and a nonlinear correlation filter is used. The complete information retrieval and authentication verification are possible provided sufficient number of photons is available. To check the robustness of the proposed scheme, attack analysis has been carried out. The simulation results are presented to demonstrate the proposed idea.     

Diethyl ether as an ignition improver for acetylene-fuelled homogeneous charge compression ignition operation: an experimental investigation

In this study, a single-cylinder, water-cooled, direct-injection, compression ignition (CI) engine is operated on the homogeneous charge CI (HCCI) mode using acetylene and diethyl ether (DEE) as fuels. Acetylene is inducted as a main fuel and a small quantity of DEE is injected into the intake manifold for controlling combustion phasing. The engine performance and exhaust emission characteristics are investigated experimentally under various operating conditions. From the results, it is found that brake thermal efficiency of the acetylene-DEE HCCI mode is comparable with that of the conventional CI mode. It has a wide operating range of 0–4.2 bar brake mean effective pressure without exhaust gas recirculation compared with the liquid fuels-HCCI mode. The engine could easily start in the HCCI mode using DEE alone. Nitric oxide and smoke emissions are at ultra-low level. Hydrocarbon emissions are comparatively lower at lower loads and higher at higher load conditions. Carbon monoxide emissions are comparable with that of the conventional CI mode.     

Image encryption based on interference that uses fractional Fourier domain asymmetric keys

We propose an image encryption technique based on the interference principle and phase-truncation approach in the fractional Fourier domain. The proposed scheme offers multiple levels of security with asymmetric keys and is free from the silhouette problem. Multiple input images bonded with random phase masks are independently fractional Fourier transformed. Amplitude truncation of obtained spectrum helps generate individual and universal keys while phase truncation generates two phase-only masks analytically. For decryption, these two phase-only masks optically interfere, and this results in the phase-truncated function in the output. After using the correct random phase mask, universal key, individual key, and fractional orders, the original image is retrieved successfully. Computer simulation results with four gray-scale images validate the proposed method. To measure the effectiveness of the proposed method, we calculated the mean square error between the original and the decrypted images. In this scheme, the encryption process and decryption keys formation are complicated and should be realized digitally. For decryption, an optoelectronic scheme has been suggested.     

Development of novel chitin/nanosilver composite scaffolds for wound dressing applications

Antibiotic resistance of microorganisms is one of the major problems faced in the field of wound care and management resulting in complications like infection and delayed wound healing. Currently a lot of research is focused on developing newer antimicrobials to treat wounds infected with antibiotic resistant microorganisms. Silver has been used as an antimicrobial agent for a long time in the form of metallic silver and silver sulfadiazine ointments. Recently silver nanoparticles have come up as a potent antimicrobial agent and are finding diverse medical applications ranging from silver based dressings to silver coated medical devices. Chitin is a natural biopolymer with properties like biocompatibility and biodegradability. It is widely used as a scaffold for tissue engineering applications. In this work, we developed and characterized novel chitin/nanosilver composite scaffolds for wound healing applications. The antibacterial, blood clotting and cytotoxicity of the prepared composite scaffolds were also studied. These chitin/nanosilver composite scaffolds were found to be bactericidal against S. aureus and E. coli and good blood clotting ability. These results suggested that these chitin/nanosilver composite scaffolds could be used for wound healing applications.     

A Rheological Approach to Viscoelastic Worm-Like Micelles of Tunable Properties

The rheological behavior of micellar solutions of cationic surfactant, cetyl trimethyl ammonium bromide in the presence of a salt (KBr) and a co-surfactant (n-octanol) were analyzed. Shear viscosity and shear moduli were measured as a function of concentrations of the co-surfactant and additive. When these concentrations attained a certain critical threshold value, the micellar solution was found to exhibit a nonlinear viscoelastic behavior. It is due to the formation of supramolecular structures, which has been described by the Maxwell model of a viscoelastic fluid typical of worm-like micelles. The rheological behavior was also analyzed using Carreau and Carreau–Gahleitner models which were found to be in good agreement with the experimental results.