Towards tuning of surface properties by atomic and molecular adsorption on boron-terminated cubic boron nitride (111) surface: A first-principles study

We present a theoretical investigation for the adsorptions of triangular nitrogen trimer radical (N₃) at both the hollow (H3) and fourfold coordinated top (T4) sites on boron-terminated (111) (B(111)) surface of cubic boron nitride (c-BN) in terms of structure, adsorption energy, band structure and work function. For the first time, we explore the H3 and T4 adsorption mechanisms. Moreover, we study the subsequent co-adsorption of N₃, boron and hydrogen atoms on the same adsorption site on the B(111) surface, which will form either pyramid quantum cluster or nearly planar adsorbate. We find that the surface band structure varies substantially depending on the types of terminated surface formed (changing from metallic to semi-conducting), and consequently, the surface work function changes. These results indicate the electronic characteristics of the B(111) surface can be tuned readily using chemical co-adsorption, suggesting its potential for chemical sensing applications.     

The effects of dietary fasting on physical balance among healthy young women

Background  

The study examined the effects of dietary fasting on physical balance among young healthy women.     

Impact of Statistical Multiplexing on Voice Quality in Cellular Networks

This paper examines the quality of transmission of voice over cellular, packet-switched networks. The medium access mechanism in the uplink is simulated under various statistical multiplexing scenarios in order to assess the effect of front-end clipping on voice quality. Moreover, the simulation is implemented in a real-time demonstration platform utilized to acquire subjective indicators of voice quality by performing Mean Opinion Score (MOS) tests. Results from the MOS tests are reported, and an analysis of the obtained speech samples is presented. Finally, the results are summarized and potential further directions for the simulation tool and the speech models are discussed.     

Predicting Marangoni convection caused by transient gas diffusion in liquids

The onset of convection driven by surface tension during gas diffusion in a liquid is investigated. Gas diffusion at the gas-liquid interface results in the variation of concentration of the solute that may cause an increase in surface tension leading to Marangoni convection. The onset of convection for unsteady-state gas desorption can be predicted from the maximum transient Ma_t, which is here derived by analogy with its equivalent in thermal convection. It is a function of the transient Biot number (Bi_D) for interfacial gas diffusion, which depends strongly on the state of vapour-liquid equilibrium at the interface. The transient Marangoni numbers, critical times for stable mass diffusion and the critical sizes of convection cells have been formulated. The desorption of ethyl-ether from chloro-benzene in L.M. Blair’s [The onset of cellular convection in a fluid layer with time-dependent density gradients, PhD thesis, University of Illinois, Urbana, 1968] experiments is liquid phase-controlled, hence, the highly soluble system is characterized by Bi_D = 0. Therefore, his experiments that were initiated with a step-change in pressure cannot be analyzed by a step-function boundary that is characterized by Bi_D = ∞. The surface concentration may change very slowly, it has been approximated to be about 0.1% of the initial pressure change at the point of onset of convection. The average critical Marangoni number for this condition was estimated to be 53.3, which is fairly close to the theoretical value of 67 for an interface with a Biot number of 0. Therefore, the high value of 3100 calculated by I.F. Davenport and C.J. King [The initiation of natural convection caused by time-dependent profiles, Lawrence Berkeley Lab, Report NBR LBL-600, 1972] is wrong, who wrongly assumed a fixed surface-concentration boundary that is applicable only to a sparingly soluble solute. The critical sizes of convection cells predicted by theory are generally less than 1 mm for reported critical times of less than 20 s, they would be difficult to measure.     

A Dual-Wavelength Fiber Laser Sensor System for Measurement of Temperature and Strain

A strain and temperature-sensing scheme based on a dual-wavelength fiber laser is demonstrated experimentally. By measuring the change in the wavelength separation of the two lasing wavelengths and the shift of any of two lasing wavelengths, the measured strain and temperature are very linear and have a strain sensitivity of 0.15 pm/muepsiv over a range of 0-2400 muepsiv and a temperature sensitivity of 14.3 pm/degC over a range of 22degC-230degC, respectively.     

Development of a direct sampling method for verifying the cleanliness of equipment shared with peanut products

A direct sampling method was developed to verify the cleanliness of stainless steel equipment used to produce peanut products. The protocol consisted of sampling the product-contact area with two Critical Swab^® flat zapped-head foam swabs pre-moistened with 20 mM phosphate, pH 7.2 (PBS), mixing each swab in PBS for 1 h, and analyzing the extract for peanut residues. Quantitation of peanut residues was accomplished with a non-specific assay while SDS–PAGE was used to ensure the recovery of the allergen, Ara h 1. This sampling approach was able to recover 90–95% of the peanut proteins at sub-microgram levels and Ara h 1 at low nanogram levels directly from a stainless steel surface.     

A VLSI architecture for variable block size video motion estimation

With the advent of new video standards such as MPEG-4 part-10 and H.264/H.26L, demands for advanced video coding, particularly in the area of variable block size video motion estimation (VBSME), are increasing. In this paper, we propose a new one-dimensional (1-D) very large-scale integration architecture for full-search VBSME (FSVBSME). The VBS sum of absolute differences (SAD) computation is performed by re-using the results of smaller sub-block computations. These are distributed and combined by incorporating a shuffling mechanism within each processing element. Whereas a conventional 1-D architecture can process only one motion vector (MV), this new architecture can process up to 41 MV sub-blocks (within a macroblock) in the same number of clock cycles.     

In vivo Doppler shift measurements using multimode fiber-opticcatheters

A new fiber-optic catheter for in vivo blood-flow measurements has been developed. The catheter is designed to measure blood flow in both the forward (toward the catheter tip) and reverse (away from the catheter tip) flow directions. It consists of two multimode optical fibers with core diameter of 50 μm and cladding diameter of 125 μm. One fiber transmits the laser beam into blood and the other receives the backscattered light from the erythrocytes within the probe volume. In the flow experiment, it was found that the flow within the boundary layer is indeed laminar and, hence, the relationship between the Doppler shift frequencies and the flow velocities is linear, thereby making the linear calibration possible for predicting the free stream flow velocity. Plots of the maximum shift frequency (frequency at which the Doppler spectrum disappeared into the noise spectrum) against the flow velocities are found to be more linear in both the forward and reverse flow directions than that of the dominant shift frequency (frequency with the highest amplitude). These results were reaffirmed by the numerical flow simulation along the catheter side wall