Digital parallelism, perpendicularity, and rectangles

The slope of digital line segments is defined and an algorithm to evaluate it is presented. Parallelism and perpendicularity of two digital line segments are also defined. Finally, rectangular digital regions are defined and characterized, and an algorithm that determines whether or not a given digital region is a digital rectangle is presented.     

Developing a limb repositioning robotic interface for persons with severe physical disabilities

Limb repositioning is necessary for individuals with severe physical disabilities to sustain muscle strength and prevent pressure sores. As robotic technologies become ubiquitous, these tools offer promise to support the repositioning process. However, research has yet to focus on ways in which individuals with severe physical disabilities can control robots for these tasks. This paper presents a study that examines the needs and attitudes of potential users with physical disabilities to control a robotic aid for limb repositioning. Subjects expressed interest in using brain–computer interface (BCI) and speech recognition technologies for purposes of executing robotic tasks. The performance of four subjects controlling arm movements on an avatar through the keyboard, mouse, BCI, and Dragon NaturallySpeaking speech recognition was evaluated. Although BCI and speech technologies may limit physical fatigue, more challenges were faced using BCI and speech conditions compared to the keyboard and mouse. This research promotes accessibility into mainstream robotic technologies and represents the first step in the development of a robotic prototype using a BCI and speech recognition technologies for limb repositioning.     

Scheduled WiFi using distributed contention in WLANs: algorithms,experiments, and case-studies

The ubiquitous adoption of WiFi introduces large diversity in types of application requirements and topological characteristics. Consequently, considerable attention is being devoted to making WiFi networks controllable without compromising their scalability. However, the main MAC protocol of WiFi, distributed coordination function (DCF), is a contention-based protocol using random backoff. Thus, operating under DCF, the access of channel is hard to control and nonpredictable. In order to provide controllability of channel access in WiFi, we propose Rhythm, a MAC protocol that achieves scheduled WiFi efficiently using distributed contention. By achieving scheduled WiFi, channel access can be controlled by manipulating the schedule decision. We evaluate the performance of Rhythm through analysis, experiments, and case-studies.     

Photocatalytic degradation of environmental perilous gentian violet dye using leucaena-mediated zinc oxide nanoparticle and its anticancer activity

Phytomediated synthesis of metal oxide nanoparticles has become a key research area in nanotechnology due to its wide applicability in various biomedical fields. The present work explores the biosynthesis of zinc oxide nanoparticles(ZnO-NPs) using Leucaena leucocephala leaf extract. The synthesised ZnO-NPs were characterised by ultraviolet-visible(UV-Vis) spectroscopy, scanning electron microscopy(SEM), energydispersive X-ray spectroscopy(EDX), Fourier transform infrared spectroscopy(FTIR), X-ray diffraction(XRD),transmission electron microscopy(TEM) and selected area electron diffraction(SAED) studies. Biosynthesised ZnONPs are found to have wurtzite hexagonal structure with particles distributed in the range of 50-200 nm as confirmed by TEM studies. The anticancer activity of ZnONPs against MCF-7(breast cancer) and PC-3(human prostate cancer) cell lines was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay. From the assay, biosynthesised ZnO-NPs have better cytotoxic activity on PC-3 cell lines than MCF-7 cell lines. The in vitro cytotoxicity studies of biosynthesised ZnO-NPs against Dalton lymphoma ascites(DLA)cells reveal better antitumor activity of 92% inhibition with concentration of 200 μg·ml~(-1) of ZnO-NPs,and as the concentration increases, the anticancer efficiency as well increases, and also, it has excellent photocatalytic activity to degrade crystal violet dye in aqueous solution after irradiation of 90 min. The result suggests that the green synthesis of ZnO-NPs could be easily recovered and reused several times without any significant loss of the catalytic activity. The advantage of this technique lies in its low cost, easily climb able and non-use of toxic agents.     

Staphylococcus aureus Exfoliative Toxin E,Oligomeric State and Flip of P186: Implications for Its Action Mechanism

Staphylococcal exfoliative toxins (ETs) are glutamyl endopeptidases that specifically cleave the Glu381-Gly382 bond in the ectodomains of desmoglein 1 (Dsg1) via complex action mechanisms. To date, four ETs have been identified in different Staphylococcus aureus strains and ETE is the most recently characterized. The unusual properties of ETs have been attributed to a unique structural feature, i.e., the 180° flip of the carbonyl oxygen (O) of the nonconserved residue 192/186 (ETA/ETE numbering), not conducive to the oxyanion hole formation. We report the crystal structure of ETE determined at 1.61 Å resolution, in which P186(O) adopts two conformations displaying a 180° rotation. This finding, together with free energy calculations, supports the existence of a dynamic transition between the conformations under the tested conditions. Moreover, enzymatic assays showed no significant differences in the esterolytic efficiency of ETE and ETE/P186G, a mutant predicted to possess a functional oxyanion hole, thus downplaying the influence of the flip on the activity. Finally, we observed the formation of ETE homodimers in solution and the predicted homodimeric structure revealed the participation of a characteristic nonconserved loop in the interface and the partial occlusion of the protein active site, suggesting that monomerization is required for enzymatic activity.     

Nonisothermal modeling of heat transfer inside an internal batch mixer

A nonisothermal transient process of temperature increase due to viscous heating was simulated for a 69 cm³ internal batch mixer (BM) using a computational fluid dynamics (CFD) software, Polyflow 3.9 form ANSYS, Inc., to obtain the temporal temperature distribution and characterize the heat transfer between polymer melt and mixer wall. The melt temperature obtained from simulation was verified with experiments. Starting from a uniform temperature of 463 K, when a rotation speed of 5.24 rad/s is imposed, viscous heating caused a maximum temperature rise of 3 K for a polyethylene (PE) resin, and 6 K for a polystyrene (PS) resin. The transient flow fields inside the batch mixer were characterized with velocity profiles and a mixing index parameter, which show that laminar flow dominates inside the mixer while a small percentage of elongational flow, converging flow, and recirculation flow is also present. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

A compact multi-source multi-substrate evaporator for thin film studies of rare earth sulphides

To facilitate materials research by thin film techniques, we have built a compact multi-source multi-substrate evaporator. We have successfully prepared crystalline binary EuS (T_c = 16 K), SmS and Sm₂S₃ as well as ternary Sm_1?xLn_xS (Ln = Tm, Yb) compounds by tenchnique of co-evaporation. Special precautions were taken to avoid sulphur contamination. The X-ray, optical and magnetic properties of these films confirmed the good quality of the samples. Optical data obtained on Sm_1?xYb_xS indicate a stable valency of 2 for Sm and Yb for all values of x.     

Preparation and characterization of some single,mixed and doped crystals and instrumentation aspects

The preparation and characterization (salient ones) of KAl (SO₄)₂. 12H₂O, KCr (SO₄)₂·12H₂O, mixed crystals of both with 10 to 90% of each component, mixed crystals of CsCl with CuCl₂, doped crystals of KBr with K₃FeCN₆, mixed crystals (NH₄)₂SO₄ with CuSO₄ or NiSO₄, NaCl with growth improver Pb⁺², Mn⁺², metallic crystals of Zn, Bi, ionic crystals of alkali halides with Pb⁺², or Cd⁺², etc. are presented. Instrumentation aspects of a rotary crystallizer, a homogeniser, an ingot release mechanism and a zone refiner are shown.