Digital signal propagation delay in a nano-circuit containing reactive and resistive elements

The transient switching delay in a micro/nano-scale circuit containing resistive and reactive elements are sternly affected by the surge in the resistance arising from sub-linear current-voltage (I-V) characteristics limited by the velocity and current saturation. The saturation arises due to the realignment of randomly oriented velocity vectors to the unidirectional streamlined ones in a high electric field when voltage applied across a resistor exceeds its decreasing critical value with reduced channel length. The frequency response f = 1/2πτt is affected by a transit time delay τt is lower than that predicted from the application of Ohm's law. The resistance surge dramatically boosts the RC time constant and switching delay and attenuates the L/R time constant and switching delay

Notions of home for diasporic Muslim women writers

Literatures on Muslim women writers living in a new land are scarce and rarely discussed. This paper aims to explore the writings by two Muslim women writers who had to leave their countries for various reasons but "returned home" through their creative work, exemplifying the diasporic notion of being ambivalent and critical of their 'homelands' (and possibly also of their 'hostlands').By scrutinising the works by Azar Nafisi, Reading Lolita in Tehran and Mohja Kahf, The Girl in the Tangerine Scarf, we will demonstrate an aspect of unsettling women and problematise the notion of 'home' for both writers. Both Nafisi and Kahf have a different way of putting forth issues relating to home but very often, politicising much of the issues raised in their attempts to address matters relating to justice and women's participation in the public domains. By investigating their notions of home, we will be able to draw some conclusions about what memories and political (read: religious) concerns they evoke and how their recollections sketch pictures of the home they no longer call their own

Surface reaction of undoped AlGaN/GaN HEMT based two terminal device in H+ and OH- ion-contained aqueous solution

Gallium nitride is considered as the most promising material for liquid-phase sensor applications due to its chemical stability and high internal piezoelectric polarization. In this work, the sensing responses of undoped-AlGaN/GaN two terminal devices upon exposure to various pH levels in aqueous solution (a mixture of HCl and NaOH) as well as their possible sensing mechanism have been investigated. No reference voltage or gate voltage is applied. The changes in drain-source current, IDS as a function of pH level were evaluated. In the acidic region, there was an almost linear change in IDS where IDS decreased with the increase in pH level. Hence, the translated channel resistance increases with the pH level. High H+ ion concentration at low pH level which corresponds to the large net positive potential on the surface leads to the enhancement of the flow of electrons in 2DEG channel. As the pH level was increased towards neutral point in the acidic region which corresponds to the increase of OH- ion concentration, the net surface potential on the surface starts to be dominated by negative potential. As a result, the 2DEG channel starts to deplete which resulted in the increase of channel resistance. The estimated current and resistance change for sensing area of 1 mm2 and drain-source voltage, VDS of 1- 6 V are in the range of 2.16-80.1 mA/pH and 154.6-500.5 kΩ/pH, respectively. However, the linear decreases of IDS were not continuously observed in the basic region where OH- ions were dominant. The IDS levels were high, showing that the flows of carriers in 2DEG channel were enhanced again. The resistance was low and almost constant in the basic region. It seems to be resulted by the formation of thin Ga(x)O(y) layer on the AlGaN surface contributed by the interaction of OH- with the Ga-face surface. Hence, the net potential on the AlGaN surface seems to be dominated again by the net positive surface potential

RF-DC power conversion of Schottky diode fabricated on AlGaAs/GaAs heterostructure for on-chip rectenna device application in nanosystems

The Schottky diodes enjoined with coplanar waveguides are investigated for applications in on-chip rectenna device applications without insertion of a matching circuit. The design, fabrication, DC characteristics and RF-to-DC conversion of the AlGaAs/GaAs HEMT Schottky diode is presented. The RF signals are well converted by the fabricated Schottky diodes with cut-off frequency up to 25 GHz estimated in direct injection experiments. The outcomes of these results provide conduit for breakthrough designs for ultra-low power on-chip rectenna device technology to be integrated in nanosystems

Reflectance characteristics of silicon surface fabricated with the arrays of uniform inverted pyramid microstructures in UV-visible range

In this paper, inverted pyramidal microstructures are designed and fabricated on silicon (Si) surface. The characteristics of surface reflectance are simulated using two-dimensional (2D) finite-difference time-domain (FDTD) method by varying the spacing (S) and width (W) of the pyramidal microstructures. The results showed that the effect of S is more significant compared to W where the reflectance of the irradiated light has been increased gradually with the increase of S from 0 to 3 µm, and the difference is around 9.6%. Due to the etching constraint, S= 3 µm is chosen for the fabrication. Textured structure is fabricated by the anisotropic etching of tetramethyl-ammonium hydroxide (TMAH) with additional of isopropyl alcohol (IPA). Long etching time of 120 min is required to form uniform arrays of pyramidal microstructures with smooth and well-terminated four sidewalls at (111) plane. Due to the undercut etching under SiO2 mask, it results to the formation of slightly larger W and smaller S in the fabricated structures. The measured average reflectance in UV-visible range for the Si with inverted pyramidal microstructures is very low down to 10.4%. The discrepancy between the measured and simulated values is speculated to be due to the use of 2D FDTD instead of three-dimensional (3D) FDTD

Back-to-back schottky diode from vacuum filtered and chemically reduced graphene oxide

This paper presents fabrication of reduced graphene oxide (rGO)/silicon (Si) back-to-back Schottky diode (BBSD) through graphene oxide (GO) thin film formation by vacuum filtration and chemical reduction of the film via ascorbic acid. In order to understand and assess the viability of these two processes, process condition and parameters were varied and analyzed. It was confirmed that the GO film thickness could be controlled by changing GO dispersion volume and concentration. Filtration of 200 ml of 0.4 ppm GO dispersion produced average film thickness of 53 nm. As for the reduction process, long duration was required to produce higher reduction degree. rGO film that underwent two times reduction at before and after transfer process with concentrated ascorbic acid gave the lowest sheet resistance of 3.58 MΩ/sq. In the final part of the paper, result of the BBSD device fabrication and current-voltage characterization were shown. The formed two rGO/Si Schottky junctions in the BBSD gave barrier height of 0.63 and 0.7 eV. The presented results confirmed the viability of fabricating rGO-based device using a simple method and without requirement of sophisticated equipment

Helping women cope with life behind bars

Implementation of group therapy in Malaysian prison through Cognitive Behavioural Therapy (CBT) approach is deemed important to improve the psychological well-being of the inmates. Numerous studies had been conducted but most of them provide statistical data based on cross-sectional studies but findings on effect of psychological treatment is still very scarce. This preliminary study aimed to examine the impacts of group therapy on psychological well-being of women prisoners, particularly in Malaysia. Sixteen women inmates from Women Prison in Selangor, Malaysia were chosen and assigned by the prison authority to receive eight group therapy sessions. The respondents in this study were of different race/ethnic groups, different faiths, socio-economical and criminal backgrounds, aged between 27 to 56 years old. Selfreport measures DASS21 was utilized to examine their psychological well-being before and after eight sessions of group therapy in a duration of four months. This study employed a pre- and post-test design study without a control group. Statistical analyses used were descriptive statistics and paired-samples t-test. The results of this study revealed that there were significant differences in psychological variables as indicated by significant decrease level of depression and stress. Although not significant, their level of anxiety has also reduced. The findings of this study the self-belief and psychological well-being of the inmates. The findings could be used to add knowledge and to better understand the inmates and the rehabilitation methods that work for them. It also give some insights if group therapy can be considered as one of the programs that can support the rehabilitation process of the inmate

Synthesis of zinc oxide nanostructures on graphene/glass substrate by electrochemical deposition: effects of current density and temperature

The electrochemical growth of zinc oxide (ZnO) nanostructures on graphene on glass using zinc nitrate hexahydrate was studied. The effects of current densities and temperatures on the morphological, structural, and optical properties of the ZnO structures were studied. Vertically aligned nanorods were obtained at a low temperature of 75°C, and the diameters increased with current density. Growth temperature seems to have a strong effect in generating well-defined hexagonal-shape nanorods with a smooth top edge surface. A film-like structure was observed for high current densities above -1.0 mA/cm2 and temperatures above 80°C due to the coalescence between the neighboring nanorods with large diameter. The nanorods grown at a temperature of 75°C with a low current density of -0.1 mA/cm2 exhibited the highest density of 1.45 × 109 cm-2. X-ray diffraction measurements revealed that the grown ZnO crystallites were highly oriented along the c-axis. The intensity ratio of the ultraviolet (UV) region emission to the visible region emission, IUV/IVIS, showed a decrement with the current densities for all grown samples. The samples grown at the current density below -0.5 mA/cm2 showed high IUV/IVIS values closer to or higher than 1.0, suggesting their fewer structural defects. For all the ZnO/ graphene structures, the high transmittance up to 65% was obtained at the light wavelength of 550 nm. Structural and optical properties of the grown ZnO structures seem to be effectively controlled by the current density rather than the growth temperature. ZnO nanorod/graphene hybrid structure on glass is expected to be a promising structure for solar cell which is a conceivable candidate to address the global need for an inexpensive alternative energy source

Effect of Growth Pressure on Structural Properties of SiC Film Grown on Insulator by Utilizing Graphene as a Buffer Layer

Heteroepitaxial growth of silicon carbide (SiC) on graphene/SiO2/Si substrates was carried out using a home-made hot-mesh chemical vapor deposition (HM-CVD) apparatus. Monomethylsilane (MMS) was used as single source gas while hydrogen (H2) as carrier gas. The substrate temperature, tungsten mesh temperature, H2 flow rate and distance between mesh and substrate were fixed at 750 °C, 1700 °C, 100 sccm and 30 mm, respectively. The growth pressures were set to 1.2, 1.8 and 2.4 Torr. The growth of 3C-SiC (111) on graphene/SiO2/Si were confirmed by the observation of θ-2θ diffraction peak at 35.68°. The diffraction peak of thin film on graphene/SiO2/Si substrate at pressure growth is 1.8 Torr is relatively more intense and sharper than thin film grown at pressure growth 1.2 and 2.4 Torr, thus indicates that the quality of grown film at 1.8 Torr is better. The sharp and strong peak at 33° was observed on the all film grown, that peak was attributed Si(200) nanocrystal. The reason why Si (200) nanocrystal layer is formed is not understood. In principle, it can’t be denied that the low quality of the grown thin film is influenced by the capability of our home-made apparatus. However, we believe that the quality can be further increased by the improvement of apparatus design. As a conclusion, the growth pressures around 1.8 Torr seems to be the best pressures for the growth of heteroepitaxial 3C-SiC thin film

Alkaloids and sulphur-containing amides from glycosmis citrifolia and glycosmis elongata

Air-dried leaves of both Glycosmis citrifolia and Glycosmis elongata collected from Bogor Botanical Garden, Indonesia were individually extracted with chloroform to give dark viscous extracts after solvent removal. Column chromatographic separation of the extract of G. citrifolia yielded 5(6)-glutene-3α-ol, two sets conformers, (E)-dambullin and (Z)-dambullin, and (E)-methyldambullin and (Z)-methyldambullin. Similar treatment of the extract of G. elongata gave skimmianine and arborinine. The structures of the compounds were elucidated based on spectroscopic data and comparison with published reports