Absence Of Groove Research Articles

Rapid mixing achieved using Coriolis force and grooves in rotating microchannels

Mixing is a critical process in reagent reactions used in biomedical applications. Nevertheless, achieving rapid mixing in microfluidics is challenging because of the low-Reynolds region. This study numerically investigated the mixing performance of a rotating channel based on the Coriolis force with herringbone grooves. In the absence of grooves, the mixing was maximized when the Coriolis force was appropriately balanced with the centrifugal force. As the aspect ratio increased from 0.5 to 2.0, rapid mixing was achieved owing to the decreased transverse distance between the rotating flows. Mixing improved with the herringbone grooves, achieving up to >90% for the shortest channel length (20 mm) among the various microchannels. This enhancement resulted from the flow split and recombination induced by the combination of the Coriolis force and grooves. This study will help create and design microchannels for disk chip miniaturization, automation, and integration into lab-on-a-disk-based biomedical procedures, such as point-of-care diagnosis.

Anomocephalobus, a new genus of minute marsh-loving beetles from mid-Cretaceous Burmese amber (Coleoptera: Limnichidae)

Limnichidae are currently a moderately diverse beetle family with a sparse fossil record. Here we describe a new limnichid genus and species, Anomocephalobus liuhaoi Li, Jäch & Cai gen. et sp. nov., from the mid-Cretaceous amber from northern Myanmar. Anomocephalobus gen. nov. is tentatively assigned to the extant subfamily Cephalobyrrhinae, based on its transverse metacoxae, 5-segmented protarsi, and absence of grooves on the ventral surface for reception of legs, though its oval body shape is somewhat deviating from extant Cephalobyrrhinae. The generic placement of the recently described Erichia cretacea Yu, Ślipiński, Ren & Pang, 2018 is also discussed.

A new genus and two new species of oonopid spiders from Myanmar (Araneae, Oonopidae).

A new genus, Promolotragen. nov., including two new species, P. hponkanrazisp. nov. (♂♀) and P. shankhaungsp. nov. (♂), is described from Myanmar. The new genus is similar to Molotra Ubick & Griswold, 2011 but can be distinguished by the completely fused bulb and cymbium, the presence of a receptacle, the absence of grooves connecting either the anterior or posterior pairs of spiracles, and the incised labium of both sexes.

Effects of silicon carbide contents on microstructure and mechanical properties of spark plasma–sintered titanium-based metal matrix

In this study, TiNiAl-SiC composites (TMCs) containing 1, 3, and 6 wt% SiC were prepared by spark plasma sintering (SPS) process using heating rate of 100 °C/min, at 800 °C, and sintering pressure of 40 MPa, and holding time of 10 min. Phase identification was carried out on TiNiAl-SiC composites by X-ray diffraction technique. Microstructure and elemental analyses were done with a scanning electron microscope (SEM) and energy dispersive X-ray (EDS) spectroscopy. SEM micrographs showed pronounced grain boundary interaction between the SiC and the TiNiAl matrix with increase wt% SiC. The results from the mechanical characterization generally showed enhancement in hardness, tensile strength, yield strength, and wear. At 6 wt% SiC, the optimum values of 2852 MPa, 930.46 MPa, and 673.02 MPa were established for hardness, tensile strength, and yield strength, respectively. Also, TiNiAl-SiC composite with 6 wt% SiC presented the best frictional profile with the highest resisting power due to the lowest friction coefficient of about 0.4, and the wear rate of 2.18 mm3/m. The absence of grooves in the worn morphology also confirmed that it has good tribological properties.

Photoelastic Analysis of Two Different Cementless Femoral Stems for Total Hip Arthroplasty in a Canine Model

Objectives The aim of this article was to analyse and compare internal stress generated at different points of a femoral photoelastic model after insertion and axial load application using two different cementless femoral stems for total hip arthroplasty in dogs: a collared stem combined with limited textured surface and absence of grooves and a collarless stem with fully textured surface and grooves. Methods Ten femoral photoelastic models, divided into two groups, were created using two different designs of cementless femoral stems. The models were submitted to axial loading on the femoral head in a universal test machine. The internal stress (kPa) around the femoral stems was evaluated at seven predetermined points using a transmission polariscope. Results The internal stress at the femoral calcar was larger in the models with collared stem combined with limited textured surface and absence of grooves (p < 0.05). No differences were identified between the groups in the other points (p > 0.05), corresponding to the tip of the stems and proximal lateral region of the femur. Conclusions The collar of femoral stem combined with the absence of grooves and more limited textured surface increase the axial load transmission to the femoral calcar, and in vivo, it may act to reduce complications, such as subsidence and stress shielding. However, other biomechanical tests and clinical evaluations must be performed to determine other important aspects for the implantation of these prostheses.

Morphological study of proximal root grooves and their influence on periodontal attachment loss.

Background:The etiology of periodontal diseases is multifactorial including both systemic and local causes. Local factors such as grooves on root surfaces contribute a great deal to the causation of periodontal diseases.Materials and Methods:Proximal radicular grooves were studied in 150 extracted maxillary and mandibular anterior teeth. Periodontal attachment loss was measured after staining the root surfaces with 0.1% toluidine blue stain. The relationship of the presence and absence of grooves with periodontal attachment loss was also studied.Results:The prevalence of proximal root grooves was found to be 86.67%. The prevalence of grooves on maxillary teeth was 43.42% and on mandibular teeth was 56.67%. A greater loss of attachment was present on grooved surfaces than on nongrooved surfaces.Conclusion:The proximal radicular grooves present as one of the major etiological factors in periodontal diseases.

New instability mode in a grooved channel

It is known that longitudinal grooves may stabilize or destabilize the travelling wave instability in a channel flow depending on the groove wavenumber. These waves reduce to the classical Tollmien–Schlichting waves in the absence of grooves. It is shown that another class of travelling wave instability exists if grooves with sufficiently high amplitude and proper wavelengths are used. It is demonstrated that the new instability mode is driven by the inviscid mechanism, with the disturbance motion having the form of a wave propagating in the streamwise direction with phase speed approximately four times larger than the Tollmien–Schlichting wave speed and with its streamwise wavelength being approximately twice the spanwise groove wavelength. The instability motion is concentrated mostly in the middle of the channel and has a planar character, i.e. the dominant velocity components are parallel to the walls. A significant reduction of the corresponding critical Reynolds number can be achieved by increasing the groove amplitude. Conditions that guarantee the flow stability in a grooved channel, i.e. the grooved surface behaves as a hydraulically smooth surface, have been identified.

Premiers temps du Magdalénien en Gironde : réévaluation des fouilles Trécolle à Saint-Germain-la-Rivière (France)

The Magdalenian site of Saint-Germain-la-Rivière (Gironde, France) has often figured in debates and discussions about the Late Upper Palaeolithic of Western Europe. Most of the discussions are based on the material excavated by R. Blanchard — in particular the now well-known burial — as well as the more rigorous excavations by G. Trécolle in the slope deposits. After the detailed study of all this material by M. Lenoir, which allowed the material from the slope and terrace deposits to be attributed to the Lower and Middle Magdalenian, many other studies were carried out by various researchers on specific aspects of the collections (lithics, personal ornaments, fauna). It became clear, however, that the stratigraphic framework and chronology of the site needed to be reexamined. In order to understand the rise of the classic Magdalenian in Gironde, members of the Magdatis project reexamined many early Middle Magdalenian sites and collections of that area. The thorough work of Trécolle at Saint-Germain-la-Rivière was pivotal to this reas sessment. Initially, this involved the analysis of his fieldnotes which led to an archaeostratigraphic reattribution of most artefacts into two principal units, with a potentially problematic interface between these. Once these new archaeostratigraphic divisions had been determined, analysis of the artefacts could proceed. The comparison of the lithic and bone/ antler industries with those of other sites has afforded us new insights into the nature of the types of technical and economic behaviour of this initial Magdalenian in Western Europe. In terms of lithic and osseous raw material, we have found a good degree of continuity between the two units. The differing treatment of domestic versus hunting flint tools is also an important aspect to consider in the discussion of the changes that took place in huntergatherer societies at this time. The bone/ antler industry shows some continuity between units (for example the use of the groove and splinter technique), but also some differences (in the upper unit : less diversity in tools ; a higher frequency of decorated objects). The systematization of standardized blade production in the upper unit is accompanied by an increase in size of antler points. The production of different lithic projectile morphotypes (backed microbladelets versus scalene bladelets), in parallel with a change in base types within antler points, in addition to the presence or absence of grooves, demonstrate that changes occurred in the toolkits used. A reassessment of the faunal remains also helped to clarify the practices having occurred in each of the two principal stratigraphic units ; combined with a taphonomic analysis, the specific subsistence practices in each could be identified. Different hunting strategies were noticed regarding saiga antelope (hunting within female groups versus mixed herds) as well as differing carcass treatment (degree of intensity of marrow extraction, carcass processing techniques). Our analysis also revealed that small-game hunting (birds and small mammals) had already been practised in the earliest Magdalenian phases at the site, thus providing a more complete picture of these reindeer and saiga antelope hunters. Taking into account all of these data and practices allows us to be more specific about the type and pace of technical and subsistence changes having occurred during this period. New 14C dates taken directly from bones of identified species or characteristic organic artefacts also aid us in shedding new light on the two main phases of the Magdalenian. The Trécolle excavation and its collections can thus be placed within the overall Saint-Germain-la-Rivière site sequence and compared with other contemporaneous sites in Western Europe which have also benefited from a renewed stratigraphic, archaeological and chronological assessment and framework.

Action of the insect growth regulator fluazuron, the active ingredient of the acaricide Acatak®, inRhipicephalus sanguineusnymphs (Latreille, 1806) (Acari: Ixodidae)

The present study evaluated the efficacy of fluazuron (active ingredient of the acaricide Acatak®) and its effects on Rhipicephalus sanguineus nymphs fed on rabbits exposed to different doses of this insect growth regulator. Three different doses of fluazuron (20 mg/kg, 40 mg/kg, and 80 mg/kg) were applied on the back of hosts (via "pour on"), while distilled water was applied to the Control group. On the first day of treatment with fluazuron (24 h), hosts were artificially infested with R. sanguineus nymphs. Once fully engorged, nymphs were removed and placed in identified Petri dishes in Biochemical Oxygen Demand (BOD) incubator for 7 days. After this period, engorged nymphs were processed for ultramorphological analysis. The results revealed alterations in the ultramorphology of many chitinous structures (smaller hypostome and chelicerae, less sclerotized scutum, fewer sensilla, fewer pores, absence of grooves, marginal and cervical strips and festoons in the body, even the anal plaque was damaged) that play essential roles for the survivor of ticks and that can compromise the total or partial development of nymphs and emergence of adults after periodic molting. Our findings confirm the efficacy of fluazuron, a more specific and less aggressive chemical to the environment and human health, and that does not induce resistance, in nymphs of the tick R. sanguineus in artificially infested rabbits treated with this arthropod growth regulator (AGR), indicating that it could be used in the control of this stage of the biological cycle of the tick R. sanguineus.

The Identity and Morphology of the Three Species of Drynaria (Polypodiaceae) in Bukidnon, Philippines

The objective of the study was to compare the morphoanatomical characters of the species of Drynaria found in Bukidnon, Philippines .The species identified were Drynaria quercifolia (Linn) Sm., D. sparsisora (Desv.) and Moore, D. rigidula (Sw.) Bedd. Morphoanatomical comparisons of the three species of Drynaria showed some similarities such as long creeping and branched rhizome, mature fertile fronds green and sterile fronds brown, leathery and with shiny upper surface and exindusiate sori. On the other hand, differences were observed in the plant height, type of lamina, presence or absence of groove in the stipe, costa and rachis, length and width, margin, fertile and sterile fronds attachment to the rhizome, base, apex, paleae, hair shape and sori arrangement. Anatomically, the five species also differed in the attachment of paleae to the rhizomes, length, width, number and shape of vascular bundles in the stipe, costa and rachis, presence and absence of hypodermis, type of stomata, length, width, number of subsidiary cells, walls of epidermal cells, the cortical arrangement of the tissues in the costa and midvein of the pinna. Based on their morpho-anatomical differences, a taxonomic key was constructed to identify the three species of Drynaria . Keywords - morphology, anatomy, systematic, Drynaria , Bukidnon

Brief communication: Histology and micro CT as methods for assessment of facial suture patency

The extent of fusion in facial sutures has implications for topics ranging from biomechanics to phylogeny reconstruction. An unfortunate limitation of studying sutural fusion in skeletal specimens is that it is difficult to assess whether apparently patent sutures are in fact fused internally. Both histology and microcomputed tomography (CT) are potential tools for solving this, but relatively few studies have attempted to discern the limits of micro CT for visualization of microanatomical structures. We examined microanatomical aspects of facial sutures in adult cadaveric samples from captive bushbabies. Premaxillary and nasopremaxillary sutures were examined in serially sectioned snouts of four greater bushbabies (Otolemur garnettii) and four lesser bushbabies (Galago moholi). Sections containing sutures with osseous bridging were rated as "fused," and the presence or absence of grooves on the external side was recorded. One bushbaby was studied using micro CT prior to physical sectioning. O. garnettii and two of the G. moholi show multiple foci of fusion. Histological examination confirmed that sutural fusion is limited to the internal surface in numerous sections, resulting in an external notch. Such points of internal fusion could be clearly visualized in raw CT slices. The presence of such notches suggests that external examination can underestimate the degree of suture fusion. Thus, microanatomical evidence may be needed to fully assess biomechanical correlates and phylogenetic interpretations based on fusion of facial sutures. Our results also indicate micro CT may be a useful tool to obtain this evidence.

Propagation of a shear-horizontal surface acoustic mode in a periodically grooved AlN/Al2O3 microstructure

We investigate the shear-horizontal surface acoustic waves (SH-SAWs) generated on an AlN/Al2O3 microstructure by laser-micromachined grooves on the AlN film. In the absence of grooves, the AlN/Al2O3 device shows resonance for only a lower velocity SAW mode. However, when grooves of periodicity smaller than half the wavelength of the surface acoustic wave are micromachined, a higher velocity resonance due to a SH-SAW mode is observed in the device. It is found that our SH-SAW mode remains undamped and is able to propagate across the device when loaded with a biofluidic mass. We have also measured the mass sensitivity of the SH-SAW mode under biofludic load in terms of frequency shift. Measurements show that this mode has a very high mass sensitivity of the order 1.35 ng/ml, which suggests that the device can be applied for the detection of a small concentration of antigens in a biofluid. In this article, the fabrication and grooving techniques of the device are also addressed.

Taxonomic Status of the Snake Genera Conopsis and Toluca (Colubridae)

The taxonomic history of the colubrid genera Conopsis and Toluca is complex and has been reviewed by Goyenechea and Flores-Villela (2000). The single character purportedly differentiating them has been called into question by several authors (e.g., Bogert and Oliver, 1945). Some workers recognize just one genus for this group (Bogert and Oliver, 1945; Goyenechea, 1995), whereas others have regarded the two genera as valid (Boulenger, 1894; Duges, 1896; Duellman, 1961). Taylor and Smith (1942) reviewed these genera and concluded that each was valid. According to these authors, species of Toluca have a groove on each posterior maxillary tooth, that is lacking in species of Conopsis. In spite of the review by Taylor and Smith (1942), the generic status of Conopsis and Toluca was questioned by Bogert and Oliver (1945) because the latter did not consider the putative diagnostic character sufficient for recognizing the genus Toluca. In addition to the presence or absence of grooves in the posterior maxillary teeth, another morphological character purportedly differentiating these genera is the condition of the loreal scale (Taylor and Smith, 1942). In Conopsis, the loreal scale may be present or fused with the nasal, whereas it is completely absent in Toluca. As part of revisionary work on these snakes, we reevaluated these putative, diagnostic features in all recognized taxa of both genera to assess their taxonomic utility, since the only way to allocate specimens to particular species has been on the basis of geographic provenance. We examined 659 museum specimens, including 199 Conopsis and 460 Toluca that represented all known taxa (10 species and subspecies) from throughout the geographical range of both genera (both are endemic to Mexico, distributed from Chihuahua to Oaxaca), in order to reevaluate their taxonomic status. The following characters were recorded: snout-vent length (SVL), total length (TL), diameter of the body (DIAM), number of ventral and subcaudal scales, supralabials, infralabials, presence-absence of the nasal, loreal, preocular, postocular, frontal, and genial scales, temporal formula, shape of the hemipenis, and dorsal and ventral color pattern. To determine the presence or absence of tooth grooves, maxillae were dissected on 43 specimens (Appendix 1) representing all recognized species and subspecies of each genus. One maxilla

Improvement of the cantilever grooveless gate

1. The grooveless multisectional gate permits closing openings of any width without dividing the conduit into sevetal smaller openings at the place of gate installation. 2. The absence of grooves and piers improves the hydraulic conditions of the entire conduit's operation. 3. The use of water pressure for operating the gate eliminates the need for powerful hoists. 4. For heads up to 70–80 m the multisectional grooveless mechanical-acting gate without a pressure chamber which does not impose high demands on the accuracy of installing the roller paths and facings of the gate guide, has the greatest prospects.

Falcaustra chabaudi sp. n. (Nematoda: Kathlaniidae) from the Western Lesser Siren, Siren intermedia nettingi Goin, 1942

Falcaustra chabaudi sp. n. is described from 7 males and 10 females collected from the large intestine of the western lesser siren, Siren intermedia nettingi, in southern Illinois. This species most closely resembles F. cryptobranchi (Walton, 1930) Freitas and Lent, 1941, from which it differs by the absence of grooves spiraling part-way around the head, in the conformation of the anterior esophageal bulb, and in having spicules 1.21 to 1.34 mm long. F. chabaudi is differentiated from F. catesbeianae Walton, 1929, the only species in Falcaustra reported from the genus Siren. Seventeen undescribed kathlaniid nematodes, identified as members of the genus Falcaustra (= Spironoura), were found in the large intestine of two western lesser sirens, Siren intermedia nettingi Goin, 1942. A summary of the various species of this genus is included in the works of Freitas and Lent (1941), Chabaud and Golvan (1957), Walton (1964), and Khalil (1970). The material used for the following description was fixed in hot 70% ethanol, stored in 70% ethanol containing 5% glycerine, and cleared by standard glycerine dehydration technique. Specimens were temporarily mounted in pure glycerine and studied with light and phase contrast microscopes. All measurements are in microns unless otherwise indicated. Illustrations were made with the aid of a camera

A new way of repairing and strengthening sheet steel parts that are have abrasive wear during operation

The article describes a technical solution that relates to the field of mechanical engineering and repair of machines, in particular to the restoration and simultaneous strengthening of steel sheet parts, which, depending on the conditions of external influence, various types of abrasive wear. The method involves removing the worn part of the workpiece and replacing it with a separate segment. The segment is also made of sheet material, and connect it to the recoverable part with an integral connection. According to one variant of the technical solution, the segment has a pre-made groove, which is attached to the recoverable part with a pre-made thorn. Strengthening of the recovered part is carried out by the method of electro-erosion alloying (EEA) to achieve the desired hardness of the segment. Before creating an integral connection of the recoverable part and the surface of the groove surface of the segment is covered with metal-polymer material (MPM). According to the second variant of the technical solution, the segment has a pre-made thorn, and the recoverable part is a groove. The technical result of the solution is the absence of grooves, as well as improving the hardness and wear resistance of the recovered and hardened parts in the conditions of intensive abrasive wear, the ability to use as a reducing material wear-resistant metals with any degree of weldability, low energy consumption and environmental safety.