Effect Of Probe Length Research Articles

Effect of probe length on tensile strength of dissimilar friction stir welded lap-joint between AA6061 and 316 stainless steel using marine structure

Recently, optimizing marine structure have been facing with a lot of challenges to reducing weight, increasing strength, and improving resistance corrosion. Using dissimilar joint may be one of the suitable solutions for manufacturer. In this study, dissimilar lap-joints between aluminum alloys 6061 and 316 stainless steel was produced by friction stir welding technology. The attention was put on the effect of different probe lengths on joint strength. The probe length was arranged from 2.7 mm to 2.9 mm. The experimental results show that the tensile strength of lap-joints increased with long probe length. The highest tensile strength is obtained approximately 6976 at the probe length of 2.9 mm that fracture location was found at aluminum side. The impact of interface properties on the joint strength was investigated and analyzed in this work. Key works: Dissimilar joint, FSW, probe length, tensile strength.

Process-intensified extraction of phycocyanin followed by β-carotene from Spirulina platensis using ultrasound-assisted extraction

ABSTRACTThe development of sustainable technology for the extraction of value-added products from the ecological feedstock is gaining importance. The present work focuses on the intensification of extraction of different metabolites such as phycocyanin and β carotene from microalgae (Spirulina platensis) and also presents the optimum extraction parameters using an ultrasound-assisted approach. Initially, phycocyanin was extracted from lyophilized biomass of Spirulina platensis using an ultrasound-assisted approach, and then the extract was centrifuged and the supernatant was treated by using the sugaring-out method to separate phycocyanin from chlorophyll. The remaining biomass was further used for the extraction of β-carotene using the same ultrasound-assisted approach. Various operating parameters such as amplitude, duty cycle, sonication time, and depth of horn immersed into the solution have been investigated for intensified extraction. Moreover, Taguchi design of experiments was used to evaluate the yield of β-carotene using the L9 orthogonal array based on the effect of probe length, amplitude, duty cycle, and sonication time. On the basis of results and signal-to-noise (S/N) ratio analysis, a ranking of the parameters was performed. It can be noted here that the order of ranking was amplitude > sonication time > duty cycle > depth of horn immersing into the solution. Overall, it has been observed that maximum extraction of phycocyanin and β-carotene was 67 mg/g of dry biomass and 4.66 mg/g of dry weight, which was obtained at optimal amplitudes of 80% and 66% of the duty cycle and 0.5 cm depth of horn immersing into the solution in 4 min and 10 min, respectively. The present study clearly demonstrated that significant intensification benefits can be obtained in terms of the extraction of metabolites at optimal conditions using the ultrasound-assisted approach.

Effects of Probe Length, Probe Geometry, and Redox-Tag Placement on the Performance of the Electrochemical E-DNA Sensor

Previous work has described several reagentless, electrochemical DNA (E-DNA) sensing architectures comprised of an electrode-immobilized, redox-tagged probe oligonucleotide. Recent studies suggest that E-DNA signaling is predicated on hybridization-linked changes in probe flexibility, which will alter the efficiency with which the terminal redox tag strikes the electrode. This, in turn, suggests that probe length, probe geometry, and redox-tag placement will affect E-DNA signaling. To test this we have characterized E-DNA sensors comprised of linear or stem-loop probes of various lengths and with redox tags placed either distal to the electrode or internally within the probe sequence (proximal). We find that linear probes produce larger signal changes upon target binding than equivalent stem-loop probes. Likewise, long probes exhibit greater signal changes than short probes provided that the redox tag is placed proximal to the electrode surface. In contrast to their improved signaling, the specificity of long probes is poorer than that of short probes, suggesting that sensor optimization represents a trade off between sensitivity and specificity. Finally, we find that sensor response time and selectivity are only minimally affected by probe geometry or length. The results of this comparative study will help guide future designs and applications of these sensors.

Effect of tool geometry on microstructure and static strength in friction stir spot welded aluminium alloys

The effect of tool geometry on microstructure and static strength in friction stir spot welds of 6061 aluminium alloy sheets was studied. Tools with three different probe lengths were used to join the aluminium sheet with different tool rotational speeds and tool holding times. The weld microstructures varied significantly depending on probe length, tool rotational speed and tool holding time. Two particular aspects were identified: the thickness of the upper sheet under the shoulder indentation and the nugget size. The former decreased with increasing probe length at the shortest tool holding time and the slowest tool rotational speed, but there were no discernible differences in other welding conditions, while the latter increased with increasing probe length, tool rotational speed and tool holding time. The tensile shear strength increased with increasing probe length, while the cross-tension strength was not affected significantly by probe length. Two fracture modes were observed: shear fracture of the nugget and mixed mode fracture under tensile shear loading, and nugget debonding and pull-out under cross-tension loading. Based on experimental observation of the microstructures, the effect of probe length on static strength and the fracture mechanisms were discussed.

Quenched autoligation probes allow discrimination of live bacterial species by single nucleotide differences in rRNA

Quenched autoligation (QUAL) probes are a class of self-reacting nucleic acid probes that give strong fluorescence signal in the presence of fully complementary RNAs and selectivity against single nucleotide differences in solution. Here, we describe experiments designed to test whether QUAL probes can discriminate between bacterial species by the detection of small differences in their 16S rRNA sequences. Probes were introduced into live cells using small amounts of detergent, thus eliminating the need for fixation, and fluorescence signal was monitored both by microscopy and by flow cytometry without any washing steps. The effects of probe length, modified backbone, probe concentration and growth state of the bacteria were investigated. The data demonstrate specific fluorescence discrimination between three closely related bacteria, Escherichia coli, Salmonella enterica and Pseudomonas putida, based on single nucleotide differences in their 16S rRNA. Discrimination was possible with cells in mid-log phase or in lag phase. These results suggest that QUAL probes may be useful for rapid identification of microorganisms in laboratory and clinical settings.

The effects of probe length on Fitts’ law

Experiments were aimed at determining the effect of a human using an extended probe when making movements that required accuracy at the completion of the movement. Ten subjects performed 64 conditions of varying amplitude of movement, final accuracy and probe length. Movement time increased with probe lengths from 100 to 400 mm for all conditions of amplitude and required accuracy. The effect of probe length was included in a mathematical description of the data through a multiplicative term on Fitts’ index of difficulty ( ID), possibly arising from tremor of the hand/probe system in controlling approach to the target. Probe length had the greatest effect at high ID, where a probe of 400 mm length increased movement time by about 25% over that for a 100 mm probe. The model developed has application for accurate movements with long tools such as screwdrivers or crowbars, head-mounted devices for the disabled, or other tasks where the work interface is at the end of an extended probe.

Application of long synthetic oligonucleotides for gene analysis: Effect of probe length and stringency conditions on hybridization specificity

Two different lengths of long unique synthetic oligonucleotide probes (37- and 48-mers) specific for human major histocompatibility complex (MHC) class II beta genes were synthesized. These oligonucleotides were utilized to examine factors influencing hybridization specificity. Both probe length and stringency of washing conditions were found to be crucial factors for sequence-specific hybridization.