An analysis of the air-jet yarn texturing process. Part 6, The mechanism of loop formation

After a brief summary of the findings and conclusions of the previously reported investigations on the air-jet texturing process, a mechanism of loop formation is postulated. The factors affecting loop formation are analysed in the light of the mechanism described. This mechanism of loop formation is claimed to be valid for all types of texturing nozzle because the underlying requirement to create a supersonic, turbulent, and non-uniform flow is common to all satisfactory air-jet texturing nozzles

An analysis of the air-jet yarn texturing process. Part 2, Experimental investigation of the air-flow

An account is given of an experimental investigation of the characteristics of the air-flow in a scaled-up model of a currently used nozzle for the air-jet texturing of yarns. The flow was found to be supersonic, turbulent, and of a non -uniform profile. Flow visualizations of the undisturbed and disturbed flows made by using the actual-size nozzle provided evidence that challenges previously postulated mechanisms of, loop formation based on shock waves

An analysis of the air-jet yarn texturing process. Part 4, Fluid forces acting on the filaments and the effects of filament cross-sectional area and shape

Fluid (drag) forces acting on filaments in an air-flow are theoretically analysed, and equations to calculate them are derived. Drag forces acting on filaments are shown to vary with the filament cross-section, the position of the filaments across the nozzle, and the local air velocity. Since finer filaments have a smaller inertial resistance to fluid forces and have lower stiffness, yarns with finer filaments are shown to be more suitable for air-jet texturing. Theoretical modelling of a lament as it emerges from the nozzle shows that, for filaments with identical linear densities, those with cross sections having reduced bending and torsional stiffness, such as elhpt1c cross-sections, may be more suitable for air-jet texturing

An analysis of the air-jet yarn texturing process. Part 5, The effect of wetting the yarns

It is shown that the quantity of water mixing into the air-flow is an insignificant proportion of the total amount of water used in the air-jet texturing process and that this has a negligible effect on the air-flow in the texturing nozzle. It is suggested that only a fraction of this water is needed to impart the desired effects of wetting. Experimental investigations show that water acts as a lubricant to reduce the filament-filament and filament-solid-surface friction and hence aids the longitudinal displacements of the filaments relative to each other. A realignment of the yarn path minimizes the friction between the filaments and solid surfaces

An analysis of the air-jet yarn texturing process. Part 3, Filament behaviour during texturing

Experiments performed with a current industrial-texturing nozzle on a specially designed singlehead texturing machine are described. These involve the use of high-speed still and cine photography, together with measurements of yam speed on emergence from the nozzle and yarn-tension measurements at various stages of the process. The results of these experiments provide a better understanding of the filament behaviour during the texturing process. They also provide useful information regarding the effects of texturing speed, overfeed ratio, and texturing with and without water on the mechanisms of the process

Loop formation mechanism in the air-jet texturing process

A brief introduction to the air-jet texturing process is given, with reference to similarities between air-jet textured yarns and spun yarns, differences between them and stretch yarns, and developments in texturing nozzles. Researches undertaken at various universities on the investigation of the loop formation mechanism are reviewed. An alternative explanation of the loop formation mechanism is offered by detailed reference to current research in the Department of Mechanical Engineering at Loughborough University of Technology, this being based on high-speed photography and flow measurement methods applied mainly to the standard core HemaJet produced by Heberlein of Switzerland. It is argued that the suggested mechanism applies generally to all texturing nozzles

Response of Vegetation to Livestock Grazing at the Texas Experimental Ranch.

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Synaptophysin sustains presynaptic performance by preserving vesicular synaptobrevin-II levels

The two most abundant molecules on synaptic vesicles (SVs) are synaptophysin and synaptobrevin-II (sybII). SybII is essential for SV fusion, whereas synaptophysin is proposed to control the trafficking of sybII after SV fusion and its retrieval during endocytosis. Despite controlling key aspects of sybII packaging into SVs, the absence of synaptophysin results in negligible effects on neurotransmission. We hypothesised that this apparent absence of effect may be because of the abundance of sybII on SVs, with the impact of inefficient sybII retrieval only revealed during periods of repeated SV turnover. To test this hypothesis, we subjected primary cultures of synaptophysin knockout neurons to repeated trains of neuronal activity, while monitoring SV fusion events and levels of vesicular sybII. We identified a significant decrease in both the number of SV fusion events (monitored using the genetically encoded reporter vesicular glutamate transporter-pHluorin) and vesicular sybII levels (via both immunofluorescence and Western blotting) using this protocol. This revealed that synaptophysin is essential to sustain both parameters during periods of repetitive SV turnover. This was confirmed by the rescue of presynaptic performance by the expression of exogenous synaptophysin. Importantly, the expression of exogenous sybII also fully restored SV fusion events in synaptophysin knockout neurons. The ability of additional copies of sybII to fully rescue presynaptic performance in these knockout neurons suggests that the principal role of synaptophysin is to mediate the efficient retrieval of sybII to sustain neurotransmitter release

Next-to-leading order QCD corrections to A_TT for prompt photon production

We present a next-to-leading order QCD calculation of the cross section for isolated large-p_T prompt photon production in collisions of transversely polarized protons. We devise a simple method of dealing with the phase space integrals in dimensional regularization in the presence of the cos(2 phi) azimuthal-angular dependence occurring for transverse polarization. Our results allow to calculate the double-spin asymmetry A_TT for this process at next-to-leading order accuracy, which may be used at BNL-RHIC to measure the transversity parton distributions of the proton.Comment: 19 pages, LaTeX, 2 figures as eps file

Flow-duration curve integration into digital filtering algorithms for simulating climate variability based on river baseflow

A baseflow separation methodology combining the outcomes of the flow–duration curve and the digital filtering algorithms to cope with the restrictions of the traditional procedures has been assessed. Using this methodology as well as the monitored and simulated hydro-climatologic data, the baseflow annual variations due to climate change and human-induced activities were determined. The outcomes show that the long-term baseflow index at the upstream sub-basin is nearly half of that at the downstream from October to April, whereas, they are close to each other for the remaining months. Some of the groundwater reacts to precipitation and an evident rise in the groundwater contribution has been detected for the hydrological years 1998–2001 and 2006–2008. The contrary has been recorded for 1987. The water released from the reservoir in the dry periods lead to distinctions in the detected baseflow index between the pre-damming and post-damming periods of the river