Sharif Digital Repository

Herein, we demonstrate a simple yet novel luminescence assay for visual chiral discrimination of cysteine. Thioglycolic acid (TGA)-capped cadmium-telluride (CdTe) quantum dots (QDs) exposing green emission were directly synthesized in aqueous solution. The interaction between cysteine molecules and CdTe QDs induced the aggregation of QDs via hydrogen bonding. As a result of electronic coupling within these aggregates, a redshift both in the absorption and emission spectra of QDs occured. The difference in the kinetics of the interactions between L- A nd D-cysteine with CdTe QDs led to chiral recognition of these enantiomers. Addition of D-cysteine to CdTe QDs in a basic media caused a... 

The resistance and capacitance values of the water samples are measured by using two different cell probes (length 10 cm and 5 cm) and a measuring module. Measured conductivities for the different water samples are compared where the lowest conductivity is obtained for the distilled water (3.28 μS/cm) and the highest value is for the boiled water 325.91 μS/cm. Using the measured series resistance values, and by knowing the frequency (1 kHz), the imaginary part of permittivity value is also determined. The imaginary part of the permittivity for the distilled water with the long cell probe is about 0.524 × 10 -7 F/m (for the short probe is 0.523 × 10-7 F/m) while for the boiled water sample is... 

Design and operation of a light reflection system for surface profiling is reported in this article. This system consists of a double-fiber optical probe and a mechanical scanning system. In this arrangement one fiber transmits the source light to the object surface and the second one transmits the light reflected off the surface to a photodetector. By scanning the double-fiber probe assembly in one direction the reflection properties of different plane surfaces are investigated. The reported system can be used to monitor the surface profile of target surfaces made from metallic and non-metallic materials. Obtained results show that the reported method can be utilized to obtain structural... 

Being able to optimal design and fabrication of compressors requires understanding of the flow structure through the compressor components. Volutes are commonly the last main component in radial flow compressors. The stream passes through inlet, impeller and diffuser and finally is collected and discharged to the downstream pipeline by a volute. Volute shape has a direct and non-negligible effect on the compressor performance and its stable operating range. This component causes distorted pressure field in the upstream flow passages which could lead to the aero-mechanical forces acting on the impeller. As the flow inside the volute is fully three dimensional and turbulent, better... 

This work aims to compare results of dissipating and pure dephasing single-qubit probes in characterizing the cutoff frequency of a harmonic reservoir Ohmic spectral density. In particular, we proved that a dissipating single-qubit improves the estimation precision of the cutoff frequency estimator. The information backflow and outflow of the dissipating and the dephasing single-qubit are compared. The relation between the quantum Fisher information and the information outflow and backflow of the probe is obtained. The results show that difference between the values of information outflow and backflow of a dissipating single-qubit is larger than a dephasing single-qubit. So, a single-qubit... 

A new genetic algorithm (GA) based method for direct calibration of 2-D hot-wire probe and other instruments that can measure 2-D flow properties is introduced. This new method is an alternative for the previous QR method that is commonly used for calibration of the X-probe hot wires. The proposed GA method resulted in a much smaller error in the velocity estimation while preserving the number of sentences in its calibration equation format. In addition, it preserves the magnitude of its error even when the number of sentences in the calibration equation is decreased while the error in the QR method increases substantially for the same situation. Furthermore, the results were much closer to... 

A new, simple and rapid carbon dot (CD) based fluorescent probe for speciation of Fe2+ and Fe3+ ions was developed. The as-prepared CDs contain phenol groups on their surfaces and due to the special coordination interaction of phenol groups with Fe3+ ions, this sensing system exhibits excellent sensitivity and selectivity toward Fe3+. In order to detect Fe2+ ions as well, a specific amount of H2O2 was introduced to the detection system to transform Fe2+ to Fe3+ of which the latter is the determinable form of iron. Under the optimum experimental conditions, the fluorescence intensity of the sensor decreased as the Fe3+ ion concentration increased. The relationship plot between the... 

Coordinate Measuring Machines (CMMs) are designed for precision inspection of complex industrial products. The mechanical accuracy of CMMs depends on both static and dynamic sources of error. In automated CMMs, one of the dynamic error sources is vibration of the probe, due to inertia forces resulting from parts acceleration and deceleration. Modeling of a gantry type CMM, based on the Timoshenko beam theory with moving mass effects, is developed and the dynamic errors of the probe resulting from the acceleration and deceleration of moving parts, are calculated. Findings from analytical solution and dynamic modeling software indicate high accuracy and good agreement between the results. ©... 

In dual-beam optical traps, the precision of position/force measurements is often compromised by crosstalk, i.e. imperfect separation of the two signals. We devise a simple yet very efficient method to perform crosstalk eliminating spatial filtering  

Air–water flow is a complex and challenging subject in many engineering fields as well as hydraulic engineering; and discovery of its characteristics can help the engineers to predict and analyze a probable phenomenon. In the present paper, development of a device capable of measuring the flow velocity, air concentration, diameter and counts of bubbles in air–water flows is described. The heart of the present device is two resistive probes with a novel configuration. Being pressure and corrosion resistant and also having negligible resistivity in the flow are some of the unique features of the employed needles. Moreover, sampling frequency and time can be adjusted for the intended... 

Friction-Stir Processing (FSP) was applied on AA1050 Aluminum Alloy (AA) to find the highest mechanical properties among 28 combinations of the rotational and traverse speed (800-2000 rpm and 50-200 mm.min-1) and four different tool probe shapes (threaded, columnar, square and triangle). To this aim, the AA standard sheet went through a single pass of FSP. The 1600 rpm and 100 mm.min-1 with threaded tool probe was chosen as the best combination of rotational and traverse speed. Grain size at the Stirred Zone (SZ) was studied using Optical Microscopy (OM). The results showed that the SZ’s grain size was refined from 30 μm down to about 12 μm due to dynamic recrystallization during FSP. The... 

In this paper, a special probe is designed using an array of photodiodes and a 960 nm LED for recording the wrist photoplethysmogram (PPG). The design is based on Monte-Carlo simulation of light propagation in tissues. Two series of experiments were carried-out: normal breathing and deep breathing. In both experiments, finger and wrist PPG were simultaneously recorded from the index finger. In the first series of experiment, signals from 9 subjects were recorded and the correlation coefficient for the raw signals (AC+DC), the AC and DC components of wrist and finger PPG were (62.5% ± 12.1%), (91.2% ± 6.9%) and (61% ± 13.4%) respectively. In the second series of experiment (deep breathing),... 

The resonant frequencies and torsional sensitivities of an atomic force microscope (AFM) assembled cantilever probe which comprises a horizontal cantilever, two vertical extensions and two tips located at their free ends are studied. This probe makes the AFM capable of measuring, for instance, the outer/inner diameter, roundness and roughness of microstructures like micro-holes and micro nozzles which leads to a time-saving swift scanning process. In this work, the effects of the sample surface contact stiffness and the geometrical parameters such as the ratio of the vertical extension length to the horizontal cantilever length and the distance of the first vertical extension from the... 

The resonant frequencies and torsional sensitivities of an atomic force microscope (AFM) with assembled cantilever probe (ACP) are studied. This ACP comprises a horizontal cantilever, a vertical extension and two tips located at the free ends of the cantilever and the extension which makes the AFM capable of simultaneous topography at top-surface and sidewalls of microstructures especially microgears which consequently leads to a time-saving swift scanning process. In this work, the effects of the sample surface contact stiffness and the geometrical parameters such as the ratio of the vertical extension length to the horizontal cantilever length and the distance of the vertical extension... 

The resonant frequencies and flexural sensitivities of an atomic force microscope (AFM) assembled cantilever probe which comprises a horizontal cantilever, a vertical extension and two tips located at the free ends of the cantilever and the extension are studied. This probe makes the AFM capable of simultaneous topography at top-surface and sidewalls of microstructures especially microgears which leads to a time-saving swift scanning process. In this work, the effects of the sample surface contact stiffness and the geometrical parameters such as the ratio of the vertical extension length to the horizontal cantilever length and the distance of the vertical extension from clamped end of the... 

The effect of surface and interface elasticity in analysis of the Saint-Venant torsion problem of an eccentrically two-phase circular nanobar is considered. The problem is formulated in the context of Gurtin's surface elasticity. For a rigorous solution of the proposed problem, conformal mapping together with a Laurent series expansion are employed. At the nanoscales the usual classical theories cease to hold and the corresponding results deteriorate. The numerical results well illustrate that the torsional rigidity of the mentioned nanosized structural elements are significantly affected by the size. Some applications of the given results can be contemplated in the design of micro/nano... 

In this study, using analytical method, the torsional resonant frequency and torsional sensitivity of the first four modes of an AFM cantilever with sidewall probe including a horizontal cantilever and a vertical extension is analyzed and a closed form for torsional sensitivity of the probe is derived. In addition, the effect of relative parameters such as ratio of vertical extension length to horizontal cantilever length is investigated. According to this study, the results show that as contact stiffness increases, the resonant frequencies of all vibration modes increases until they reach constant values at very high values of contact stiffness. It is also can be found that low-order modes... 

In this study, using analytical method, the torsional resonant frequency and torsional sensitivity of the first four modes of an AFM cantilever with sidewall probe including a horizontal cantilever and a vertical extension is analyzed and a closed form for torsional sensitivity of the probe is derived. In addition, the effect of relative parameters such as ratio of vertical extension length to horizontal cantilever length is investigated. According to this study, the results show that as contact stiffness increases, the resonant frequencies of all vibration modes increases until they reach constant values at very high values of contact stiffness. It is also can be found that low-order modes...