Conventional VG Research Articles

Evaluation of Double-Sided Plasma Vortex Generator in Comparison with Vane Vortex Generator on Separation Control

The present research has introduced a new type of Plasma Vortex Generator named as Double-Sided Plasma Vortex Generator (DSPVG) that has dual expose electrodes on both sides. This DSPVG is placed normal to the surface parallel to incoming air and creates vortices on it’s both sides. As conventional VG has an angle with flow direction which introduce device drag, to overcome this, DSPVG is placed with zero angle with flow direction; besides due to the smaller thickness and frontal area with incoming air than VGs, the drag penalty due to its geometry is minimised. Furthermore, as vortices are created on both sides, DSPVG is expected to reduce the number of Plasma Vortex Generator (PVG) with respect to the conventional embedded PVGs or VGs on the flow controlling surface. Hence, it is able to take advantage of height like conventional VGs and active control systems of PVGs with dual vortices on both sides. The impact of DSPVG on separation control has been investigated experimentally and compared its effectiveness with conventional vane VGs. Three different types of flow measurement techniques have been used to confirm the repeatability and consistency of the experimental results. Numerical investigations have been carried out to evaluate the experimental results. These findings show that the DSPVG is capable to eliminate the separation similarly to the conventional VGs but with higher momentum injection and more effective in minimizing drag penalty in the uncontrolled case as in OFF condition of DSPVG, there is no alternation of local flow which is generally affected in case of VGs that adds drag penalty.

Molecular evolution of bumble bee vitellogenin and vitellogenin-like genes.

Vitellogenin (Vg), a storage protein, has been significantly studied for its egg yolk precursor role in oviparous animals. Recent studies found that vitellogenin and its Vg‐like homologs were fundamentally involved in many other biological processes in social insects such as female caste differences and oxidative stress resilience. In this study, we conducted the first large‐scale molecular evolutionary analyses of vitellogenin coding genes (Vg) and Vg‐like genes of bumble bees, a primitively eusocial insect belonging to the genus Bombus. We obtained sequences for each of the four genes (Vg, Vg‐like‐A, Vg‐like‐B, and Vg‐like‐C) from 27 bumble bee genomes (nine were newly sequenced in this study), and sequences from the two closest clades of Bombus, including five Apis species and five Tetragonula species. Our molecular evolutionary analyses show that in bumble bee, the conventional Vg experienced strong positive selection, while the Vg‐like genes showed overall relaxation of purifying selection. In Apis and Tetragonula; however, all four genes were found under purifying selection. Furthermore, the conventional Vg showed signs of strong positive selection in most subgenera in Bombus, apart from the obligate parasitic subgenus Psithyrus which has no caste differentiation. Together, these results indicate that the conventional Vg, a key pleiotropic gene in social insects, is the most rapidly evolving copy, potentially due to its multiple known social functions for both worker and queen castes. This study shows that concerted evolution and purifying selection shaped the evolution of the Vg gene family following their ancient gene duplication and may be the leading forces behind the evolution of new potential protein function enabling functional social pleiotropy.

Expressions of conventional vitellogenin and vitellogenin-like A in worker brains are associated with a nursing task in a ponerine ant.

In eusocial insect colonies, non-reproductive workers often perform different tasks. Tasks of an individual worker are shifted depending on various factors, e.g., age and colony demography. Although a vitellogenin (Vg) gene play regulatory roles in both reproductive and non-reproductive division of labours in a honeybee, it has been shown that the insect Vg underwent multiple gene duplications and sub-functionalisation, especially in apical ant lineages. The regulatory roles of duplicated Vgs were suggested to change evolutionarily among ants, whereas such roles in phylogenetically basal ants remain unclear. Here, we examined the expression patterns of conventional Vg (CVg), Vg-like A, Vg-like B and Vg-like C, as well as Vg receptor, during the task shift in an age-dependent manner and under experimental manipulation of colony demography in a primitive ant Diacamma sp. Expressions of CVg and Vg-like A in a brain were associated with a nursing task. It is suggested that associations of brain expressions of these Vgs with worker tasks were acquired in the basal ant lineage, and that such Vg functions could have sub-functionalised in the derived ant lineage.

Influence of binder type on performance of dense bituminous mixture prepared with coarse recycled concrete aggregate

Conventional stone aggregates are becoming scare and costly because of huge infrastructure activities going on since last three decades in India. On the other hand, wastes such as that resulting from old concrete constructions are abundantly available. Many attempts have already been made to utilise these wastes referred to as recycled concrete aggregate (RCA) in various constructions including in bituminous paving layers. All types of bituminous binders commonly used in paving mixes in India may not be compatible with RCA. This experimental study aims to study the influence of binder type on the performance of dense graded bituminous mixtures containing RCA replacing the coarse fraction of conventional stone aggregates. In order to achieve this main objective, dense bituminous macadam (DBM) mixtures as per the relevant Indian specifications were prepared using three different types of bituminous binders commonly used in India, namely conventional VG 30 and VG 40 bitumens, and crumb rubber modified binder (CRMB). Separate Marshall samples were prepared using RCA and natural aggregate (NA) and either of the above three binders. As per the main scope of this study, the mixtures thus prepared were evaluated in terms of their engineering properties such as Marshall characteristics, indirect tensile strength, moisture susceptibility characteristics, resilient modulus and rutting resistance. It is observed that all mixtures considered in this study, in general satisfy the requirements in terms of Marshall and moisture susceptibility characteristics. Considering all engineering properties studied, the CRMB/VG40 bitumen offer superior and satisfactory results for mixtures containing either NA or RCA, with NA showing slightly better result as compared with RCA in the mixtures.

Effect of filler on bituminous base layer containing recycled concrete aggregates

Abstract The use of different filler materials is one of the effective techniques adopted to improve pavement quality and performance. The main purpose of this study is to quantify the influence of filler type on the performance of dense graded bituminous mixes containing recycled concrete aggregate (RCA). This RCA is replacing the coarse portion of the conventional natural aggregates (NA). In this present experimental investigation, the dense bituminous macadam (DBM) mixes according to the relevant Indian specifications are compacted using four different types of fillers, such as cement, stone dust, fly ash and carbon black and conventional VG 30 as binder. Eight different sets of Marshall samples are prepared using RCA and NA representing the coarse aggregate fraction and either of the above four binders. Different mixes thus prepared are evaluated in terms of their Marshall parameters, indirect tensile strength, moisture susceptibility characteristics (tensile strength ratio and retained stability) and resilient modulus. From the experiment conducted in the laboratory, it is found that all the mixes, in general satisfy the requirements in terms of Marshall and moisture susceptibility characteristics. Considering all engineering properties studied the mixes with NA and carbon black (CB) as filler material offered higher results comparable with other mixes. However, the mixtures prepared with RCA also offered a promising result compared to mixtures made with NA.

Vitellogenin and vitellogenin-like gene expression patterns in relation to caste and task in the ant Formica fusca

Social insect colonies are characterized by division of labour, and extensive morphological, physiological and behavioural differences between queens and workers. The storage protein vitellogenin (Vg) affects multiple aspects of social insect life histories, and has been suggested as a key player for caste differentiation and maintenance. Recently, three genes homologous to Vg have been described in the ant Formica exsecta. Their role is currently unclear but their structural variation suggests variable functions. We examined the expression patterns of the conventional Vg and the three Vg-like genes using qRT-PCR in the common black ant Formica fusca between queens and workers, between nurse and foragers workers, and across social contexts (queenless vs. queenright nests), and sampling time. As expected, we found a significant queen caste and nurse task-related increase for the conventional Vg, while Vg-like-C displayed a consistent forager-biased expression pattern. Task (forager vs. nurse) was the only factor that explained expression variation among workers in any of the studied genes. The removal of the queen did not affect expression, although the proportion of fertile nurses increased in queenless nests. The observed expression biases suggest that in Formica fusca, the ancestral duplication has led to alternative social functions for Vg-like genes across castes and tasks. To get a broader picture of the role of gene duplications in social evolution and the roles of Vg-like genes in caste differentiation and maintenance, how these genes achieve these roles at a molecular level need to be investigated further.

Gene expression is more strongly associated with behavioural specialization than with age or fertility in ant workers.

The ecological success of social insects is based on division of labour, not only between queens and workers, but also among workers. Whether a worker tends the brood or forages is influenced by age, fertility and nutritional status, with brood carers being younger, more fecund and more corpulent. Here, we experimentally disentangle behavioural specialization from age and fertility inTemnothorax longispinosus ant workers and analyse how these parameters are linked to whole-body gene expression. A total of 3,644 genes were associated with behavioural specialization which is ten times more than associated with age and 50 times more than associated with fertility. Brood carers were characterized by an upregulation of three Vitellogenin (Vg) genes, one of which, Vg-like A, was the most differentially expressed gene that was recently shown experimentally to control the switch from brood to worker care. The expression of Conventional Vg was unlinked to behavioural specialization, age or fertility, which contrasts to studies on bees and some ants. Diversity in Vg/Vg-like copy number and expression bias across ants supports subfunctionalization of Vg genes and indicates that some regulatory mechanisms of division of labour diverged in different ant lineages. Simulations revealed that our experimental dissociation of co-varying factors reduced transcriptomic noise, suggesting that confounding factors could potentially explain inconsistencies across transcriptomic studies of behavioural specialization in ants. Thus, our study reveals that worker gene expression is mainly linked to the worker's function for the colony and provides novel insights into the evolution of sociality in ants.

Comparative Study of Complications in CV Catheter Insertion for Pediatric Patients: Real-time Ultrasound-guided Versus Venography-guided Approach.

Tunneled central venous catheters (CVC), called Broviac/Hickman catheter, are widely used in the long-term treatment of pediatric patients. Recently, the percutaneous approach for CVC insertion has become dominant as a less invasive intervention. In this study, we reviewed the mechanical and delayed complications according to different procedures of CVC insertion and assessed the risk factors for complications in CVC insertions for pediatric patients. A total of 159 pediatric patients (85 males and 74 females) were included in this study. Primary reasons for indication of CVC settlement were hemato-oncologic disorders (66 cases, 42%), malignant solid tumors (30, 19%) and other benign diseases (63, 40%). CVC insertion was performed with surgical venous cut-down (CD) in 51 patients (32%), with real-time ultrasound-guided puncture (RTUS) in 57 (36%), and venography-guided puncture (VG) in 49 (31%). CD was dominantly selected and the frequency of venipuncture increased respective to the increased age of patients. RTUS was dominantly selected for one to four year old patients and VG was dominant in 5 to 15 year old patients. Some types of mechanical complication were observed in 4 of 159 (2.5%) and some delayed types were observed in 66 of 159 cases (42%). No mechanical complications occurred in cases with CD and RTUS; on the other hand, 3 (6%) of 49 insertions with VG were observed. However, we could not show any significant risk factors for the mechanical complications. In the meantime, delayed complications and premature removal were significantly observed in patients under 5 years old. RTUS is superior to our conventional VG considering less frequent mechanical complications. High frequent delayed complication and premature removal should be considered, especially for patients under 5 years old.

Effect of Binder Type, Binder Content, Aggregate Gradation, Temperature and Air Voids on Rutting Susceptibility of Bituminous Mixes

Abstract This paper presents an experimental investigation carried out to evaluate the rutting susceptibility of bituminous mixes. The effect of binder type and content, aggregate gradation and temperature are evaluated by means of a wheel tracking test. Two conventional VG 30 and VG 40 binders and one SBS polymer modified binder PMB 40 are used. Three types of aggregate gradations for bituminous concrete (BC), a dense graded mix commonly used surface course in the bituminous pavements in India have been considered. Wheel tracking tests are conducted at temperatures of 30, 40, 50 and 60 °C. Test results show that at high temperatures, polymer modified bituminous mixes performed better than the mixes prepared with conventional binders. However, the difference between rutting in mixes prepared with VG 40 and PMB 40 binders was marginal. Mixes with Superpave gradation performed better compared to the mixes with midpoint gradation. Keywords: aggregate, binder, bituminous mix, gradation, rutting

Not only for egg yolk--functional and evolutionary insights from expression, selection, and structural analyses of Formica ant vitellogenins.

Vitellogenin (Vg), a storage protein, has been extensively studied for its egg-yolk precursor role, and it has been suggested to be fundamentally involved in caste differences in social insects. More than one Vg copy has been reported in several oviparous species, including ants. However, the number and function of different Vgs, their phylogenetic relatedness, and their role in reproductive queens and nonreproductive workers have been studied in few species only. We studied caste-biased expression of Vgs in seven Formica ant species. Only one copy of conventional Vg was identified in Formica species, and three Vg homologs, derived from ancient duplications, which represent yet undiscovered Vg-like genes. We show that each of these Vg-like genes is present in all studied Hymenoptera and some of them in other insects as well. We show that after each major duplication event, at least one of the Vg-like genes has experienced a period of positive selection. This, combined with the observation that the Vg-like genes have acquired or lost specific protein domains suggests sub- or neofunctionalization between Vg and the duplicated genes. In contrast to earlier studies, Vg was not consistently queen biased in its expression, and the caste bias of the three Vg-like genes was highly variable among species. Furthermore, a truncated and Hymenoptera-specific Vg-like gene, Vg-like-C, was consistently worker biased. Multispecies comparisons are essential for Vg expression studies, and for gene expression studies in general, as we show that expression and also, putative functions cannot be generalized even among closely related species.

Utilization of Ripe Coconut Fiber in Stone Matrix Asphalt Mixes

Stone Matrix Asphalt (SMA) is a gap graded mix; characterized by higher proportion of coarse aggregate, lower proportion of middle size aggregate and higher proportion of mineral filler. In the present laboratory study, commonly available one conventional VG 30 bitumen and another modified binder, namely CRMB 60 have been used along with a non-conventional natural fiber, namely coconut fiber which is abundantly available in India to provide improved engineering properties and at the same time preventing the usual draining of binder in SMA. The role of a particular binder and fiber with respect to their concentrations in the mix is studied for various engineering properties. Marshall procedure has been followed to determine the optimum binder and optimum fiber contents and also to study the relative advantages of fiber addition in the SMA mixtures. Thereafter, the engineering properties under both static as well as repeated load conditions and moisture susceptibility characteristics have been studied. It is observed that only a marginal 0.3% coconut fiber addition brings significant improvement in the engineering properties of SMA mixes.

Isotope ratios determination of uranium in soil samples affected due to Chernobyl accident using thermal ionisation mass spectrometer

A rapid and highly precise method was developed for the separation of uranium from soil samples for thermal ionisation mass spectrometry. The chemical separation procedure is based on the use of anion exchange resin and UTEVA extraction chromatography column. The isotope ratios of uranium, 234 U/ 238 U, 235 U/ 238 U and 236 U/ 238 U were measured by using a VG Sector 54 TIMS equipped with a Wide Aperture Retardation Potential (WARP) energy filter with a precision of better than 0.2% at two standard deviations (sd). The use of a WARP energy filter improves abundance sensitivity by an order of magnitude over a conventional VG Sector TIMS. Replicates of standard reference materials showed excellent analytical agreement with established values, supporting the reliability and accuracy of the method. Uranium isotopic compositions have been determined in soil samples in the exclusion zone of Chernobyl nuclear power plant. The isotopic composition of Chernobyl soil samples showed significant deviation from the natural uranium and the 236 U/ 238 U ratio varied from 105 to 10 4.

Precise determination of 235U/238U isotope ratio in soil samples by using thermal ionisation mass spectrometry

A rapid method based on extraction chromatography was developed for the separation of uranium from soil samples for TIMS. The isotope ratios were measured on three standards using a VG 54-30 thermal ionisation mass spectrometer in static mode with Faraday cup and Daly ion counting system. The use of a WARP (Wide Aperture Retardation Potential) energy filter improves abundance sensitivity by an order of magnitude over a conventional VG Sector TIMS. An abundance sensitivity of 28 ppb at mass 237 with respect to 238U can be achieved. By correcting mass bias as a function of ion beam intensity, precision of the 235U/238U ratio was enhanced with a sample load of around 300 ng U. The resulting reproducibility for standards and soil samples was better than 0.2% at two standard deviations. Uranium isotopic compositions have been determined in soil samples and compared between Chernobyl nuclear accident site and the criticality accident, which occurred in Japan at the JCO site.

Thorium isotope ratio measurements at high abundance sensitivity using a VG54-30®, an energy-filtered thermal ionization mass spectrometer

Th isotope ratios have been measured on 3 standards using a VG54-30® mass spectrometer in static mode with a Faraday cup and ion counting Daly. The use of a 30-cm energy filter improves abundance sensitivity by an order of magnitude over a conventional VG Sector54 mass spectrometer. An abundance sensittivity of1·10−7 at mass 237 with respect to mass 238 and5·10−8 at mass 230 with respect to mass 232 can be achieved. Analysis of one standard on 4 different instruments over 18 months gives an accurate result compared with the alpha-counted value with a total external precision of±0.85% (1 standard deviation). Thus the instrument is capable of routine Th isotope ratio measurements.