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This paper presents a theoretical study on the propagation of electromagnetic surface waves supported by the metamaterial-filled bi-layered graphene structure. The effective surface conductivity approach based upon the Kubo’s formalism is used to model the atomically thick graphene layer, while the analytical modeling of the metamaterials used the framework of causality principle-based Kramers-Kroing relations. With respect to the index of refraction, the two configurations of metamaterials have been considered—i.e., double positive (DPS) and double negative (DNG). The impedance boundary conditions (IBCs) have been employed at the interface for the computation of characteristics equations of odd and even surface modes under DPS and DNG configurations. The numerical results regarding the dispersion relations, effective mode index, and phase speed for the odd and even modes of electromagnetic surface waves supported by each configuration of structure have been presented. Further, the influence of chemical potential and thickness of metamaterial filling in parallel graphene layers on the wave propagation characteristics has been analyzed. To check the accuracy of the numerical results, special conditions were employed, which converge to the published results. The proposed work may have potential applications in plasmonic based logic designs, renewable energy devices, THz surface wave guides, and near-field communication devices.

This study examines the analytical and numerical solution of electromagnetic surface waves supported by a resistive metasurface-covered grounded metamaterial structure. To simulate the metamaterial, the Kramers–Kronig relation based on the causality principle is used, while the modeling of the resistive metasurface has been done by implementing the impedance boundary conditions. The analytical expressions for the field phasors of surface waves are developed for the transverse magnetic (TM) polarized mode and transverse electric (TE) polarized mode. The characteristic equations are computed for both modes, and the unknown propagation constant is evaluated numerically in the kernel. After computation, the dispersion curves, electric field profiles, effective mode index ($$N_{eff}$$ N eff ), and phase speeds ($$v_{p}$$ v p ) are presented for both the TM and TE polarized modes. To study the tunability of surface waves, the influence of the thickness of the metamaterial slab ($$d$$ d ), effective permittivity of the metamaterial ($$\varepsilon_{1}$$ ε 1 ), thickness of the resistive metasurface ($$t$$ t ), and effective permittivity of the metasurface ($$\varepsilon_{r}$$ ε r ) on all the numerical results has been studied. However, the geometrical parameters are found to be more sensitive to the effective mode index ($$N_{eff}$$ N eff ) and phase speed ($$v_{p}$$ v p ) of the surface waves. The results are consistent with the published results, which reflects the accuracy of the work. It is concluded that the appropriate choice of parameters can be used to achieve surface waves with the desired characteristics in the GHz range. The present work may have potential applications in surface waveguide design, surface wave speed controllers, surface communication devices, and light trapping configurations.

Integrating of ferroelectric thin films with two-dimensional materials may provide a novel and unique characteristics in the field of optoelectronics due to the coupling of their distinctive intrinsic features. A heterostructure (bismuth ferrite/zinc oxide) device is fabricated with different types of the electrode to enhance the power conversion efficiency (PCE). A single-phase multiferroic BFO thin film is grown by atomic layer deposition (ALD) method and annealed in different environments such as helium, nitrogen, and oxygen. We investigated the effect of annealing parameters and different types of electrodes on solar cell applications. We observed that the leakage current 10 orders of magnitude was reduced by decreasing in the dielectric loss. Further, the power conversion efficiency (PCE) is improved from 4.1% to 7.4% with a hybrid transparent electrode (graphene/indium tin oxide). The value of PCE is further increased at a low temperature. So, the improvement in the key parameter of bismuth ferrite thin-film evidently highlights the importance of annealing atmosphere and graphene as an electrode in BFO thin film applications in optoelectronics.

A theoretical investigation has been carried out on the propagation of hybrid surface waves supported by a chiral loaded resistive metasurface. The canonical boundary-value problem approach is used in the analytical modeling of this problem. To simulate the resistive metasurface, an impedance boundary condition is applied at the chiral-resistive metasurface interface. The characteristics equation was solved numerically in the kernel for computing the unknown value of the propagation constant ( $$\beta $$ ) against its respective frequency ( $$\omega $$ ). The numerical results reveal that the chiral loaded resistive metasurface supports the upper and lower hybrid surface modes in the GHz range. The propagation bandgap between the upper and lower hybrid surface modes is highly sensitive to the chiral strength (ξ), and the propagation bandgap can be tuned with the variation of chirality. The surface wave characteristics i.e., the dispersion curve, effective mode index ( $${N}_{\mathrm{eff}}$$ ), field profiles, and phase speeds ( $${v}_{p}$$ ), have been computed numerically for both the upper and lower hybrid surface modes. The influence of chirality (ξ), thickness ( $$t$$ ), permittivity of chiral medium ( $${\varepsilon }_{c}$$ ), and the permittivity of resistive metasurface ( $${\varepsilon }_{r}$$ ) on the resonance frequency, confinement, and phase speed of surface waves have been analyzed and their tunability has been discussed. The results’ validity has been checked under special conditions and the numerical results converge to the published results. The presented numerical results may have potential applications in chip chiral sensing, enantiomeric detection, biochemical sensing, metasurface designing, and near-field hybrid surface communication devices.

Theoretical investigation has been carried out on the tunable electromagnetic surface waves propagating along the Graphene loaded semi-infinite left-handed media (LHM) interface. The analytical modeling of the graphene has been done in the frame work of Kubo's formulation. The split ring resonators (SRRs) model and Kramers-Kronig relations-based causality principle have been used to simulate the GHz-LHMs and THz-LHMs respectively. To realize the graphene loaded LHM interface, the impedance boundary conditions (IBCs) have been employed. The dispersion curves, effective mode index, propagation length, penetration depth, phase velocity and fields profiles of surface waves supported by graphene loaded GHz-LHM and THz-LHM have been computed numerically. It has been concluded that the graphene parameters can be used to tune the characteristics of surface waves in GHz and THz range. The proposed study may have potential applications in designing the near field imaging platforms, communication devices and tunable surface wave guides.

Theoretical investigations are carried out to study hybrid SPP wave propagation along the Chiral-Graphene-Metal (CGM) interface. The Kubo formulism is used for the physical modeling of single-layer graphene and the impedance boundary conditions approach is applied at the CGM interface to compute the dispersion relationship for hybrid SPP waves. It is demonstrated that the chirality (ξ) and chemical potential (μc) parameters can be used to modulate the resonance surface plasmon frequencies of the upper and lower propagating modes. Furthermore, the propagation bandgap between the upper and the lower modes can be tuned by changing the chirality parameter. The effect of the chemical potential (μc)and the relaxation time (τ) on the normalized propagation constant, propagation length, and the effective refractive index is studied. The present work may have potential applications in optical and chiral sensing in the terahertz frequency range.

Terahertz (THz) wave interaction from graphene coated metamaterial cylinder has been investigated analytically and numerically. The analytical formulation of electromagnetic fields is being modeled in the frame work of Mie theory while the modeling of the graphene is done by random phase approximation method. The causality principle based Kramer-Kroing relations are used to simulate the DNG metamaterial, while the DPS metamaterial is modeled by the Drude relations of SiO2. The analytical formulation is developed for both parallel and perpendicular polarized waves. The impedance boundary conditions (IBC) approach is used to model the infinitely thin graphene coating on metamaterial cylinder. Further the IBC at the interface of graphene layer and metamaterial cylinder are applied to compute the unknown scattering coefficients. The efficiency factors i.e., scattering efficiency (Qsca), extinction efficiency (Qexc) & absorption efficiency (Qabs) and bistatic radar cross section (RCS) have been computed analytically as well as numerically for both micro and nano cores. The influence of graphene parameters i.e., chemical potential (μc) & scattering rate (τ1) and size of metamaterial cylinder (R) on the scattering efficiency (Qsca) and extinction efficiency (Qexc) has been analyzed for DPS and DNG cores. It is observed that the in the nano regime, for perpendicularly polarized wave, graphene coated metamaterial cylinder supports the localized surface plasmon resonance (LSPR) modes and LSPR is found sensitive to the change in the graphene parameters and core size. However, it is reported that the parallel polarized wave has same response towards the DPS and DNG cores in the nano regime. It is concluded that under suitable parameters the graphene coating may provide extraordinary degree of freedom to actively control the THz interactions i.e., scattering efficiency, extinction efficiency and bistatic RCS. The present work may have potential applications in designing and manufacturing of Electromagnetic invisibility, cloaking and target protection devices for THz region. Keywords: Scattering, Absorption, Metamaterials, Graphene, Cylinder, Eco width, Radar Cross Section (RCS), Efficiency Factors, Surface Plasmon Resonance

The active tuning of surface waves supported by left-handed materials (LHMs) is a major challenge for their practical applications and usability, and graphene has been proposed as an agent for the active tuning of surface waves. In this study, tunable surface waves supported by graphene-layered LHM structures are investigated theoretically. The analytical and numerical results are computed for transverse electric (TE) and transverse magnetic (TM)-polarized surface waves. According to the spectral range, two configurations of LHMs (i.e., gigahertz (GHz)-LHM and terahertz (THz)-LHM) are discussed. The physical modeling of graphene is done using the conductivity model based on random phase approximation-based Kubo formalism. The split ring resonator (SRR) model and Kramers–Kronig relations-based causality principle are used for the physical realization of LHMs. To simulate the graphene-layered LHM interface, impedance boundary conditions (IBCs) are applied. Numerical results are computed for dispersion curves, effective wave numbers, and field profiles of surface waves supported by graphene-covered GHz-LHM and THz-LHM. The influence of graphene parameters on the resonance frequency, dispersion curves, and confinement characteristics of surface waves is analyzed for both configurations of LHMs. It is concluded that the graphene-covered GHz-LHM structure supports the tunable surface waves as surface plasmon polaritons (SPPs) support TM-polarized waves. However, with the TE-polarized surface wave, the structure supports the surface polaritons, which do not depend upon the graphene parameters. For the case of the graphene-covered THz-LHM structure, it is concluded that the structure supports the plasmon modes for both polarized waves and the resonance frequency ranges from THz to infrared (IR). The confinement of the TE-polarized surface waves on the graphene layer can be enhanced up to fourfold as compared to the suspended monolayer graphene by using a THz-LHM substrate. Further, the numerical results are found to be consistent with the literature under special conditions. The proposed graphene-layered LHM structure may have potential uses in the active tuning of surface waves, near-field communication and imaging devices, surface waveguide design, and LHM-based metasurfaces.

In-depth analysis of hybrid SPP wave propagation at the Chiral–Graphene–Dielectric (CGD) interface is carried out. The single-layer graphene is modeled using Kubo formulism and the impedance matching boundary conditions are utilized to derive the dispersion relation. TM-TE decoupled modes at the CGD interface are shown. The effective mode index and propagation length of hybrid plasmon modes are found to be sensitive to chiral strength (ξ), chemical potential (μc), radius of waveguide, and refractive index of chiral (nc). It is observed that the cutoff values of chiral strength and radius promote Goos–Henchen effect at CGD interface. The present work may have potential applications for on-chip optical, chiral sensing and enantiomeric detection and renewable energy technologies in the terahertz frequency regime.

In this work, the theoretical study of the interaction of terahertz (THz) waves with graphene embedded into two different semi-infinite metamaterials was carried out. To model the graphene, the effective surface conductivity approach based on the Kubo formalism was used. In addition, two types of metamaterials, i.e., double-positive (DPS) and double-negative (DNG), were studied in the THz regime. The numerical modeling of metamaterials was performed in the framework of causality-principle-based Kramers–Kronig relations. The reflectance and transmittance from the graphene-embedded metamaterial structures are studied for the following four different configurations: DPS–Graphene–DPS, DPS–Graphene–DNG, DNG–Graphene–DPS, and DNG–Graphene–DNG. The influence of the chemical potential and scattering rate on the reflectance and transmittance for each configuration is analyzed. It is concluded that the DPS–Graphene–DPS and DNG–Graphene–DNG configurations behave as anti-reflectors for the THz waves, while the DPS–Graphene–DNG and DNG–Graphene–DPS configurations are suitable for THz reflector applications. Moreover, a parametric study revealed that the relative permittivity of the partnering metamaterial can be used as an additional degree of freedom to control the reflectance and transmittance of THz waves. In conclusion, the transmissive and reflective characteristics of THz waves can be controlled effectively with the appropriate choice of graphene parameters, as well as the configuration of metamaterial structures. The convergence of the analytical and numerical results is found with the published results under special conditions. The present work may have potential applications in the design of THz wave controllers, reflectors, absorbers, and anti-reflectors.

The Aetiology of Neonatal Infection in South Asia (ANISA) study is a population-based study with sites in Bangladesh, India and Pakistan. It aims to determine community-acquired incidence, etiology and associated risk factors for neonatal infections. Matiari, a rural site in Pakistan, was chosen for the study due to its high neonatal mortality rate and the presence of an established pregnancy and birth surveillance system. This article summarizes various challenges, remedial measures taken and lessons learned during the implementation of the ANISA study protocol in the unique rural setting of Matiari where the majority of births take place at home and accessibility to health care is limited.Achieving and maintaining project targets of early registration of birth and collection of biological specimens in households have been challenging in Matiari. Capturing births of study subjects that occur outside the catchment areas and those taking place during public holidays and acquiring parental consent for specimen collection from healthy controls require extensive community mobilization. Contamination and power outages that affect the laboratory equipment are 2 of the major logistic challenges faced. We keep track of pregnancy outcomes through mobile phones and reimburse the costs for birth notifications to the caller. We created separate dedicated mobile teams that visit newborns outside the catchment area and carry out possible serious bacterial infection assessments. We also formed mobile teams for specimen collection from residences of newborns as there is no facility for specimen collection at this site. Our study personnel work on holidays and weekends to improve the study's performance. We nurture strong community liaison by employing staff from within the community. We train the study physicians on communication and counseling skills required for overcoming refusal for referral and specimen collection. The contamination rate is controlled by repeated training and supervision and extensive monitoring of phlebotomy activities. The majority of phlebotomy procedures are recorded on video in the field to provide feedback to phlebotomists for improving their performance.The contextual challenges faced in field implementation of the ANISA protocol in the rural setting of Matiari are unique. These challenges are being successfully addressed through hard work, strict monitoring and improvisation. This experience can be used for improving study performance in similar settings elsewhere.

Bismuth ferrite is a multiferroic material which shows high magnetization and polarization at room temperature. In present work, the effect of Oxygen (O) vacancies on magnetic properties of bismuth ferrite nanoparticles is studied. Bismuth ferrite nanoparticles (BiFeO3) were synthesized by solution evaporation method (SEM) at room temperature. The sample was annealed under two different atmospheres such as in air and oxygen, to check the effect of O-vacancies on magnetic properties. The average crystallite size of Bismuth ferrite nanoparticles (NPs) as calculated by X-ray diffraction (XRD) falls in the range of 23–32 nm and 26–39 nm for the case of air and oxygen respectively. The crystallite size of bismuth ferrite nanoparticles increases as the temperature was varied from 450 °C to 650 °C. Further the influence of annealing temperature on the magnetic properties of the bismuth ferrite nanoparticles was also observed. It was concluded that the magnetic properties of Bismuth ferrite nanoparticles are directly interconnected to annealing atmosphere and annealing temperature. The magnetic properties were increased in the case of oxygen annealing, which actually leads in our case to an improvement of the crystallinity.

Background: Camel is vital to daily life as a source of food and means of transportation, and just as importantly, its milk and urine have been used as medicine for diverse ailments since ancient times for people living in the desert region.Aim: The current study was planned to investigate the effect of different watering regimes on physiological and hematological parameters of lactating Marecha camels during the summer season.Methods: For this purpose, 12 lactating she-camels of almost similar age (8–13 years) and parity (2–5) were selected in a completely randomized design with four animals per treatment at the Camel Breeding and Research Station Rakh Mahni District Bhakkar. The trial was completed in 60 days, while 7 days were given as an acclimatization period for adaptation. The treatments were as follows: Group-1 (G-1) considered as the control had access to water once in a day; Group-2 (G-2) had access to water once in 4 days, and Group-3 (G-3) had access to water once in 6 days. Animals were housed individually for feeding and watering in an intensive management system. The same feed consisting of green fodder (Lucerne) and gram straw (Cicer arientinum) was offered to all animals. The average ambient temperature and relative humidity were 39°C–41°C and 55%–63%, respectively.Result: The mean values (p < 0.001) of water intake were found to be 82.94 ± 1.34 l in G-3, which was higher than G-1 and G-2. Blood analysis showed that packed cell volume, white blood cells, and hemoglobin were affected significantly (p < 0.001, p < 0.01, and p < 0.05, respectively).Conclusion: No serious changes in complete blood count and physiological parameters were reported in this study. So, this shows that the camel is unique in its physiological adaptation in hot and hostile environments.

Single phase Bismuth ferrite (BiFeO 3 ) with high magnetization and polarization was synthesized by solution evaporation method (SEM) at room temperature. The influence of temperature and size of nanoparticles on magnetic properties was studied. The prepared Bismuth ferrite (BiFeO 3 ) was characterized by X-ray diffraction (XRD) to investigate the structure and size of crystal. The average crystallite size of nanoparticles (NPs) as calculated by X-ray diffraction (XRD) falls in the range of 22–31 nm. The crystallite size of Bismuth ferrite increased as the temperature varied from 450 °C to 650 °C. Magnetic properties were studied by using physical properties measurement system (PPMS). It was also observed that the magnetic properties were directly related to the size and temperature of Bismuth ferrite nanoparticles. It has been investigated that the magnetization was decreased as the temperature and crystallite size increased.

The two dimensional analytical formulation of scattering of electromagnetic wave from a perfect electromagnetic conductor (PEMC) cylinder placed in un-magnetized isotropic plasma medium is presented. The extended classical scattering theory is used. The incident wave is taken as linearly polarized wave. The analytical theory is formulated for parallel polarization (TM) and also for perpendicular polarization (TE). The numerical computation results show that backscattering and forward scattering are sensitive to electron density and effective collision frequency of plasma medium. We placed different types of cylinders (PEC, PMC and PEMC) in un-magnetized plasma medium and concluded that stealth capability of plasma increases with the placement of PEMC cylinder in plasma medium.

The scattering of electromagnetic waves by a perfect electromagnetic conductor (PEMC) cylinder coated with a homogeneous plasma anisotropic material is studied in this paper. Both of the transverse electric and the transverse magnetic polarizations of the incident waves have been analyzed and formulated. The presented analysis and formulations are general for any perfect conductor cylinder (PEC, PMC, or PEMC) with general isotropic/anisotropic material coatings that include plasma and metamaterials. The co-polarized and the cross-polarized components of the scattered fields are computed for different cases of the anisotropic plasma coated PEMC cylinders and for an anisotropic plasma column. Bistatic echo widths for the cases of PEMC, PEC (perfect electric conductor) and PMC (perfect magnetic conductor) cores have been computed and compared. The behavior of the monostatic echo width with the variation of the admittance parameter for the co-polarized and the cross polarized fields is also investigated. The comparisons of the computed results of the presented formulations with the published results of some special cases confirm the accuracy of the presented analysis.

Theoretical investigation has been carried out to study the scattering and transmission of electromagnetic energy from isotropic plasma coated circular nihility cylinder. The physical modeling of the problem is done in frame work of classical scattering theory. All the fields are expanded in terms of cylindrical vector wave functions (CVWFs). The analytical as well as numerical solution for both Transverse Electric (TE) and Transverse Magnetic (TM) polarizations is presented. The unknown scattering coefficients are computed by implementing the boundary conditions at each interface (free space/plasma and plasma/nihility). The influence of plasma parameters i.e., plasma density (ND) and effective collision frequency (v) on the bistatic echo width is analyzed and it is concluded that the plasma coating can be used to control and tune the scattering amplitude. Further it is also concluded that for the case ω > ωp the scattering amplitude is much less than for the case ω < ωp. Under special conditions, the results of present work compared with the published literature and good agreement is found.

Camels have the potential for milk, meat and draught power and can contribute a handsome share of the production of these commodities. The potential of this wonderful animal has never been realized and it could be harnessed as a prospective milk producing animal. The future of animals that can thrive under harsh environmental conditions, the camel being at the top of the list, is bright. The camel is still a neglected species in Pakistan and has not received the proper attention of researchers and scientists. The population explosion, urbanization and industrialization have expanded agricultural activities to produce more food for the rapid growing human population of the country. Cultivated areas are shrinking, thus reducing the fodder production area for buffalo and cattle. Under these circumstances we have to search for other available sources to enhance milk production. The environmental changes occurring on the earth and the water shortage in the region have also adversely affected the production potential of buffalo, cattle, goats and sheep. Under these changing ecological circumstances, rearing camel is the best option for more milk production and the proper utilization of the vast unused lands of this country. Most studies also have named the camel as an animal of great socioeconomic importance in large tracts of the industrializing world. The camel serves as a cheaper source of power for drawing water from wells, plowing and leveling land, working mini extraction mills (extracting from oil seeds), grinding wheat, corn and other grains and crushing sugarcane and pulling carts for the transportation of goods as well as people.

An experiment involving 270 straight run one-day-old Hubbard broiler chicks was conducted on floor pens to investigate the effect of different levels of energy and protein on live performance and carcass responses of broilers chicks. Six broiler starter diets with two levels of metabolizable energy (ME) i.e., 2800 and 3000kcal/kg each with three levels of crude protein (CP) i.e., 20, 21 and 22% were offered to birds from hatching to 28d of age. Similarly, six broiler finisher diets with two levels of ME i.e. 3000 and 3200kcal/kg and 3 levels of CP i.e. 16, 17 and 18%, and 18, 19 and 20%, respectively, were offered during 29-42d of age. The chicks were randomly divided into 18 replicate of 15 chicks each and there were 3 replicates under each diet. Feed intake was significantly (p

The flour of lotus rhizomes was analysed for its phytochemical composition. The tannins, saponins, hydrogen cyanide (HCN), total phenolic acids and total phosphorus contents were found to be 0.415±0.164, 0.843±0.028, 0.07±0.02, 0.578±0.05 and 0.08±0.061 g/100 g of flour, respectively. The effect of polarity of the extracting solvent on antioxidant properties of lotus rhizome was also investigated and the data was analysed statistically by using semi-empirical model. An exponential increase in the yield of total extractable components (TEC) and total phenolic acids (TPA) content was observed in response to an increase in the polarity (in terms of dipole moment) of extracting solvent. Among the extracts, highest values of TEC and TPA were investigated in water extract. The antioxidant activity of the extracts was measured in terms of reducing power and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity. The ethanolic extract was found to possess comparatively higher antioxidant properties. The present data suggests that lotus rhizomes constitute significant amounts of phytochemical compounds and are good source of antioxidants. It also suggests that the use of a mixture of solvent of varying polarity instead of a single solvent is a good option for the extraction of antioxidant compounds from lotus rhizome flour. Key words: Antioxidant activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH·) scavenging, lotus, phytochemicals, phenolic acids, semi-empirical model, saponins, tannins.

Theoretical analysis of the electromagnetic wave scattering of cylindrical waves from chiral coated nihility cylinder placed in isotropic plasma medium is carried out. The scattering problem is analytically formulated in the frame work of extended classical scattering theory. The cylindrical vector wave functions (CVWFs) are used for the expansion and representation of fields. The appropriate boundary conditions are applied on each interface i.e., Plasma/Chiral and chiral/nihility to get the unknown scattering coefficients. It is concluded that the scattering amplitude can be controlled and tuned by the plasma parameters (plasma density and effective collision frequency) as well as the chirality. Moreover, the present work has practical applications in target protection and microwave controlling devices. Under the special conditions, present work found good agreement with already published literature.