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Cheating in examinations across the globe is an issue of growing concern. This study argues that the culture of cheating in exams in Balochistan has reduced the efficiency of human resource and has resulted in producing students with high qualifications but less potential in the province. Therefore, it is very important to explore the factors contributing to cheating in exams and to suggest a course of action to mitigate the menace it poses. A quantitative research method was employed for this study. Similarly, statistical techniques such as correlation and logistic regression were conducted for statistical analysis and explanation of the study using SPSS. Theoretically, the study is inspired by rational choice theory. The findings of the study show a significant relationship between personal, institutional, and situational factors. Personal factors that contribute to cheating were found to be students' desire to excel, low GPA, and slow learning. Institutional factors include the weak administrative role of institutions, poor academic policies, overload on students, and weak performance of the teachers. Situational factors such as the poor management strategy of the examiner, time pressure, and technological tools were found to be instigating students towards cheating. The study suggests that an appropriate exam hall setting, effective monitoring, concept-oriented exams, and a strong honor code can decrease cheating.

We investigated the high dielectric constant and energy storage density for the blends of P(VDF-TrFE) copolymer and P(VDF-TrFE-CFE) terpolymer. The degradation of coercive field ([E.sub.c]) and remnant polarization ([P.sub.r]) of the copolymer under an electric field of 125 MV/m was observed and the copolymer changed into a typical relaxor ferroelectric with doping of terpolymer. The dielectric constant of P(VDF-TrFE) was found to be ~11, but was enhanced to ~55 by blending with P(VDF-TrFE-CFE) at 60 wt%. Consequently, a higher energy density of about 4.2 J/[cm.sup.3] was obtained in these blends in contrast to about 3.6 J/[cm.sup.3] in the terpolymer at the very low applied electric field of 125 MV/m. These results demonstrate the promise of blend approaches for tailoring and enhancing the dielectric properties of ferroelectric polymers., INTRODUCTION Poly(vinylidene difluoride) (PVDF)-based polymers have attracted much attention due to their multifunctional electroactive polymers with superior mechanical properties. Their potential to be used as high permittivity dielectrics [1-6], organic [...]

In this research work we study the influence of Co doping on structural, optical, dielectric and magnetic properties of γ-Fe2O3 (maghemite), which is synthesized by chemical co-precipitation process. The inverse spinel structure of γ-Fe2O3 and Co (5 wt%) doped γ-Fe2O3 nanoparticles is confirmed by X-ray Diffraction (XRD), Fourier transform Infrared and Raman techniques. The average particle size is calculated, using Transmission electron microscope is about 10.83 ± 1.83 nm and 14.76 ± 2.41 nm for undoped and Co doped maghemite nanoparticles respectively, also confirmed by XRD measurements. The introduction of Co to γ-Fe2O3 nanoparticles improves crystallization. The dielectric measurement (ϵr, tanδ) gives the deep insight of the microstructure of the samples. The dielectric constant (ϵr) reduced in case of Co doped γ-Fe2O3 nanoparticles, which is more likely due to reduction in defect density and enhancement in grain size and crystallization by introduction of Co into γ-Fe2O3 lattice. The enhancement in ac conductivity (σac) in case of Co doped γ-Fe2O3 is due to fast hopping process between Fe2+/Fe3+ in undoped maghemite, increase in conducting grain volume and charge density (detached from traps + conducting charge carriers) in Fe2+/Fe3+ and Co2+/Co3+ in doped maghemite nanoparticles. The blocking temperature shifted from 62 to 88 K, which is most possibly due to increased grain size, enhanced interaction of dipole–dipole and probably increase the potential barrier for thermal instabilities. Both samples show superparamagnetic characteristic and the saturation magnetization (Ms) is increased from 30 to 35 emu/g in case of Co doped maghemite nanoparticles. This is due to Co and lattice spins parallel alignment in maghemite nanoparticles. [ABSTRACT FROM AUTHOR]

We report the synthesis of magnetite (Fe3O4) and polyvinylpyrrolidone (PVP) coated Fe3O4 nanoparticles by chemical co-precipitation route. X-ray diffraction (XRD) and transmission electron microscope (TEM) confirm the formation of inverse spinel structure of Fe3O4. XRD peaks of PVP coated Fe3O4 nanoparticles are broad and noisy as compared to Fe3O4. The broadness of peaks is due to small size and large defect density confirmed by energy dispersive spectroscopy (EDS) and scattered area electron diffraction (SAED). Noisy behavior is due to presence of PVP. Average particle size reduced from 10.36 ± 1.97 to 6.91 ± 1.89 nm for Fe3O4 and PVP coated Fe3O4, respectively. From EDS analysis, it is confirmed that the oxygen content reduced from 33.45 to 15.30 at.% with PVP coating. The oxygen content is reduced to half in case of PVP coated Fe3O4 as compared to uncoated Fe3O4. The reduction in oxygen content reveals enhancement in oxygen vacancies. Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) confirm the PVP coating and the calculated value of thickness of the PVP layer on the surface of Fe3O4 is 2.4601 nm. Dielectric constant (εr) and dielectric loss (tanδ) exhibits the dispersion behavior. Ac conductivity (σac) increases sharply at large frequencies, which is due to enhancement in charge density (liberated charge carriers from defects + conduction charge carriers). The variation in dielectric properties and conductivity is due to Maxwell Wagner interfacial polarization and hopping of charge carriers between Fe2+/Fe3+. Magnetic properties M(T) shows reduction of blocking temperature (TB) from 86 to 75 K for uncoated and PVP coated Fe3O4 nanoparticles. Shifting of TB to lower values is consistent with particle size reduction. M(H) loops at room temperature show typical superparamagnetic behavior. Reduction in saturation magnetization (Ms) is due to the presence of nonmagnetic polymer layer on the surface of Fe3O4 nanoparticles and large number of defects (oxygen vacancies). Field cooled M(H) loops at 5 K show the antisymmetric shift of coercive field along the negative x-axis. The exchange bias field HE enhances to 227 Oe in case of PVP coated Fe3O4 nanoparticles, which is double of the 125 Oe for uncoated nanoparticles. The enhancement in HE is due to smaller sized nanoparticles having large surface to volume ratio having large defect density (oxygen vacancies). [ABSTRACT FROM AUTHOR]

The ZnO, ZnMnO, ZnMnCoO, ZnMnCoO and ZnMnCoO nanoparticles were synthesized by simple chemical precipitation technique. The effects of co-doping on the structure and magnetic properties of these nanoparticles were studied. The X-rays diffraction (XRD) scans were performed in the 2 θ range of 20°-80°. The XRD patterns, at 300 K, of all the pure and co-doped ZnO samples confirmed the formation of wurtzite-type structure. X-ray diffraction and transmission scanning electron microscope analysis indicated that the high spin Co and Mn ions were substituted for the Zn ions at tetrahedral sites. The average size of the nanoparticles were increased from 17 to 24 nm with the increase of dopants concentration. Moreover, Energy Dispersive X-ray spectroscopy (EDX) confirmed the synthesis results. All ZnMnCoO ( x = 0.0, 0.1, 0.2 and 0.4) nanoparticles samples were observed to be paramagnetic below 300 K. However, a large increase in the magnetization was observed below 40 K. This behavior, along with the negative value of the Curie-Weiss constant obtained from the linear fit to the susceptibility data below room temperature, indicated the ferromagnetic nature of the samples. The origin of ferromagnetism is likely to be the intrinsic characteristics of the Co and Mn doped samples. The high magnetization was noted for the 1 wt% Co co-doped Mn-ZnO annealed samples as compared to other samples with Co concentration above and below this threshold concentration. [ABSTRACT FROM AUTHOR]

The effect of annealing temperature on the dielectric and magnetic properties of (Co, Zn) co-doped SnO nanoparticles under air/oxygen (O) and argon (Ar) atmospheres at 600 °C have been systematically investigated. A significant decrease is observed in dielectric constant and dielectric loss resulting from the incorporation of Co and Zn into the SnO lattice. Higher dielectric constant and loss was observed in the O annealed sample. Moreover, the electrical conductivity of the (Co, Zn) co-doped SnO samples increased in comparison with that of pure SnO sample due to the increase of available charge carriers after replacement of Sn ions with Co and Zn ions. Room-temperature ferromagnetism (RTFM) was observed for both the O and Ar annealed (Co, Zn) co-doped SnO samples. However, the remanent magnetization ( Mr) varied drastically for different environmental annealing processes with Mr = 0.412 and 0.20 memu/g for the O and Ar-annealed samples, respectively. The results show that the enhanced dielectric and magnetic properties of (Co, Zn) co-doped SnO sample is strongly correlated with the increase in O vacancies. These findings not only demonstrate that (Co, Zn) co-doped SnO samples show tunable RTFM, but also suggests that RTFM can be influenced by introduction of O vacancies during O annealing. [ABSTRACT FROM AUTHOR]

After our discovery of room temperature ferromagnetism in the (Co, Ni) co-doped SnO nanoparticles by co-precipitation method, we successfully annealed all (Co, Ni) co-doped SnO diluted magnetic nanoparticles in air at 800 °C. The effect of annealing on dielectric and magnetic properties of (Co, Ni) co-doped SnO diluted magnetic nanoparticles was investigated. The as-synthesized (Co, Ni) co-doped SnO nanoparticles were annealed in air at 800 °C for 2 h in an electric furnace. The dielectric constant and dielectric loss values of all (Co, Ni) co-doped SnO samples decrease whereas, the electrical conductivity value increased with an increase in Ni co-doped concentration. Room temperature ferromagnetic behavior was observed in (Co, Ni) co-doped SnO samples. Increasing the Ni content up to 2 % leads to an increase ferromagnetic behavior and beyond that the ferromagnetic behavior decreased. A comparative study shows that (Co, Ni) co-doped SnO nanoparticles annealed in air at 800 °C have an excellent dielectric, magnetic properties and higher electrical conductivity than that of the (Co, Ni) co-doped SnO annealed in air at 600 °C, indicating that these nanoparticles can be used for high frequency devices, ultrahigh dielectric materials and spintronics. [ABSTRACT FROM AUTHOR]

In this work, the dielectric and magnetic properties of (Co, Ni) co-doped SnO nanoparticles were studied using ac impedance spectroscopy and magnetic properties measurement system or quantum design superconducting quantum interference device. Results showed that dielectric constant ( ε ), dielectric loss ( ε″), and ac electrical conductivity ( σ ) are strongly frequency dependent. A decrease in frequency was accompanied with an increase in ε and ε″ values, whereas, a decrease in the dielectric constant was observed with the increase of Ni co-doping concentration. It was found that the dielectric constant and dielectric loss values decrease, whilst AC electrical conductivity increases with increase in co-doping concentration. Magnetization measurements revealed that the Ni co-doped SnO samples exhibits room temperature ferromagnetism. The results illustrate that (Co, Ni) co-doped SnO nanoparticles have an excellent dielectric, magnetic properties, and high electrical conductivity than those of co-doped samples reported previously, indicating that these (Co, Ni) co-doped SnO materials can be suitable for the purpose of high frequency device and spintronic applications. [ABSTRACT FROM AUTHOR]

Charge-changing transitions, commonly referred to as Gamow-Teller (GT) transitions, and electron capture/ β-decay strengths for pf-shell nuclei with T=−2 at proton drip-line have been calculated using the proton-neutron quasi-particle random phase approximation (pn-QRPA) model. The total GT strength values and electron capture/ β-decay rates are needed for the study of the late stages of the stellar evolution. The pn-QRPA theory is used for a microscopic calculation of GT strength distribution functions and associated stellar electron capture/ β-decay rates of proton-rich pf-shell nuclei with T=−2 in the mass range 46≤A≤56 at proton drip-line. Standard quenching factor of 0.74, usually implemented in the shell model calculation, has been incorporated for the comparison with experimental data (wherever available). The calculated GT strength of the two proton-rich nuclei, Ni and Zn are compared with experimental data of corresponding mirror nuclei. It has been found that the pn-QRPA results are in good agreement with the experimental data as well as shell model result. It is noted that the total GT strength increases linearly with the increase of mass number. The electron capture/ β-decay rates for proton-rich nuclei are calculated on a temperature and density scale relevant to presupernova evolution of massive stars. The β decay half-lives are compared with measured and other theoretical calculations. [ABSTRACT FROM AUTHOR]

The Gamow-Teller (GT) transitions within massive stars play sumptuous role in the dynamics of core collapse supernovae. GT strength distributions and electron capture rates have been calculated for odd- A nucleus Co within the proton-neutron quasiparticles random phase approximation (pn-QRPA) formalism. The pn-QRPA results are compared with other model calculations and ( n, p) reaction experiment carried out at TRIUMF charge-exchange facility. The pn-QRPA calculated a total B( GT) strength of 3.3 for Co to be compared with the shell model value of 2.5 and the 1.9±0.1 in the ( n, p) charge-exchange reaction. Aufderheide et al. () extracted total strength equaling 2.4±0.3. The placement of GT centroid at 5.6 MeV by the pn-QRPA model is in reasonable agreement with the shell model centroid at 5.1 MeV whereas the measured GT centroid was placed at 4.4±0.3 MeV in the ( n, p) experiment. Fuller, Fowler and Newman (FFN) (, , ), placed the GT centroid at too low excitation energy of 2.0 MeV in the daughter nucleus Fe, and this misplacement led to the enhancement of FFN rates. The suppressed pn-QRPA and shell model electron capture rates are in good agreement with each other. The rates are suggestive of higher value of Y (electron-to-baryon ratio) and may contribute to a more massive homologously collapsing core resulting in a more energetic shock. It might be interesting for the simulators to check the effect of these suppressed rates on the fine-tuning of the time rate of Y, the concomitant heavy element nucleosynthesis, and, on the energetics of the subsequent shock wave. [ABSTRACT FROM AUTHOR]

The Gamow-Teller strength distribution function, B( GT), for the odd Z parent V, N− Z=5, up to 30 MeV of excitation energy in the daughter Ti is calculated in the domain of proton-neutron Quasiparticle Random Phase Approximation (pn-QRPA) theory. The pn-QRPA results are compared against other theoretical calculations, (n, p) and high resolution (d, He) reaction experiments. For the case of (d, He) reaction the calibration was performed for 0≤ E≤5.0 MeV, where the authors stressed that within this excitation energy range the Δ L=0 transition strength can be extracted with high accuracy for V. Within this energy range the current pn-QRPA total B( GT) strength 0.79 is in good agreement with the (d, He) experiment's total strength of 0.9±0.1. The pn-QRPA calculated Gamow-Teller centroid at 4.20 MeV in daughter Ti is also in good agreement with high resolution (d, He) experiment which placed the Gamow-Teller centroid at 4.1±0.4 MeV in daughter Ti. The low energy detailed Gamow-Teller structure and Gamow-Teller centroid play a sumptuous role in associated weak decay rates and consequently affect the stellar dynamics. The stellar weak rates are sensitive to the location and structure of these low-lying states in daughter Ti. The calculated electron capture rates on V in stellar matter are also in good agreement with the large scale shell model rates. [ABSTRACT FROM AUTHOR]

Gamow-Teller (GT) transitions play a preeminent role in the collapse of stellar core in the stages leading to a Type-II supernova. The microscopically calculated GT strength distributions from ground and excited states are used for the calculation of weak decay rates for the core-collapse supernova dynamics and for probing the concomitant nucleosynthesis problem. The B(GT) strength for Zn is calculated in the domain of proton-neutron Quasiparticle Random Phase Approximation (pn-QRPA) theory. No experimental insertions were made (as usually made in other pn-QRPA calculations of B(GT) strength function) to check the performance of the model for proton-rich nuclei. The calculated B(GT) strength distribution is in good agreement with measurements and shows differences with the earlier reported shell model calculation. The pn-QRPA model reproduced the measured low-lying strength for Zn better in comparison to the KB3G interaction used in the large-scale shell model calculation. The stellar weak rates are sensitive to the location and structure of these low-lying states in daughter Cu. The structure of Cu plays a sumptuous role in the nucleosynthesis of proton-rich nuclei. The primary mechanism for producing such nuclei is the rp-process and is believed to be important in the dynamics of the collapsing supermassive stars. Small changes in the binding and excitation energies can lead to significant modifications of the predictions for the synthesis of proton rich isotopes. The β-decay and electron capture (EC) rates on Zn are compared to the seminal work of Fuller, Fowler and Newman (FFN). The pn-QRPA calculated β-decay rates are generally in good agreement with the FFN calculation. However at high stellar temperatures the calculated β-decay rates are almost half of FFN rates. On the other hand, for rp-process conditions, the calculated electron capture ( β-decay) rates are bigger than FFN rates by more than a factor 2 (1.5) and may have interesting astrophysical consequences. [ABSTRACT FROM AUTHOR]

Gamow-Teller (GT) transitions play an important and consequential role in many astrophysical phenomena. These include, but are not limited to, electron and positron capture rates which determine the fate of massive stars and play an intricate role in the dynamics of core collapse. These GT± transitions rates are the significant inputs in the description of supernova explosions. GT± strength function values are sensitive to the 56Ni core excitation in the middle pf -shell region and to the size of the model space as well. We used the pn-QRPA theory for extracting the GT strength for ground and excited states of 56Ni. We then used these GT strength distributions to calculate the electron and positron capture rates which show differences with the earlier calculations. One curious finding of this paper is our enhanced electron capture rates on 56Ni at presupernova temperatures. These differences need to be taken into account for the modeling of the early stages of Type II supernova evolution. [ABSTRACT FROM AUTHOR]

Electron captures are amongst the most important weak interaction rates related to the dynamics of stellar core collapse. They play a key role in the gravitational collapse of the core of a massive star triggering the supernova explosion. Titanium isotopes are believed to have significant impact on controlling the lepton-to-baryon fraction in the late phases of evolution of core of massive stars. This work consists of the calculation of electron capture rates on titanium isotopes. The pn-QRPA theory is used to calculate electron capture rates in stellar matter. The electron capture rates are calculated over a wide range of densities (10 ≤ ρYe (g/cm³) ≤ 1011) and temperatures (107 ≤ T (K) ≤ 30 x 109). Here we also report the differences in electron capture rates with the earlier calculations including those using large scale shell model. [ABSTRACT FROM AUTHOR]

Abstract: The Gamow–Teller strength (GT) distributions and electron capture rates on 55Co and 56Ni have been calculated using the proton–neutron quasiparticle random phase approximation theory. We calculate these weak interaction mediated rates over a wide temperature (–) and density () domain. Electron capture process is one of the essential ingredients involved in the complex dynamics of supernova explosion. Our calculations of electron capture rates show differences with the reported shell model diagonalization approach calculations and are comparatively enhanced at presupernova temperatures. We note that the GT strength is fragmented over many final states. [Copyright &y& Elsevier]