Apex Size Research Articles

Effects of Apex Size on Dissolution Profiles in the USP II Paddle Apparatus

The use of apex vessels may solve coning problems associated with dissolution testing. However, excessive dissolution acceleration can reduce the discriminatory power. This study aimed to clarify how different apex vessel sizes affect the dissolution behavior of cone-forming formulations. Five apex vessels with different heights, centralities, and compendial vessels were used. The paddle rotation speed at which the coning phenomenon resolved was measured using standard particles of different densities. Three model formulations—USP prednisone tablets, atorvastatin calcium hydrate tablets, and levofloxacin fine granules—were selected, and dissolution tests were conducted at 30–100 revolutions per minute (rpm). Compared to the compendial vessels, the disappearance of standard particles at the apex base at lower paddle speeds in apex vessels was observed. Standard particles tended to remain in the center of the apex vessels and disappear at rotational speeds comparable to those of the compendial vessels. Dissolution increased in an apex height-dependent manner in the model formulations, except for the atorvastatin calcium hydrate tablets at 50 rpm. For levofloxacin fine granules, dissolution was also improved by reducing the paddle agitation speed to 30 rpm in the compendial vessels. Differences in apex centrality by 3 mm did not affect the dissolution rate. Our results indicate that apex vessels with low apex heights have a mount-resolving effect, but the degree of dissolution improvement by avoiding the coning phenomenon depends on the formulation characteristics used in the dissolution tests.Graphical abstract

Bioactive Endodontic Hydrogels: From Parameters to Personalized Medicine.

Regenerative endodontic procedures (REPs) aim at recreating dental pulp tissue using biomaterials such as hydrogels. Their bioactivity is mostly related to the nature of biomolecules or chemical compounds that compose the endodontic hydrogel. However, many other parameters, such as hydrogel concentration, bioactive molecules solubility, and apex size, were reported to influence the reciprocal host-biomaterial relationship and hydrogel behavior. The lack of knowledge regarding these various parameters, which should be considered, leads to the inability to predict the clinical outcome and suggests that the biological activity of endodontic hydrogel is impossible to anticipate and could hinder the bench-to-bedside transition. We describe, in this review, that most of these parameters could be identified, described, and studied. A second part of the review lists some challenges and perspectives, including development of future mathematical models that are able to explain, and eventually predict, the bioactivity of endodontic hydrogel used in a clinical setting.

Accuracy of the KontrolFlex AccuFile when used with the Root ZX electronic apex locator in vitro.

The aims of this study were to determine the efficacy of the KontrolFlex™ Accufile™ compared to the READY•STEEL™ Flexofile® using an electronic apex locator and to evaluate the instrument's design via scanning electron microscopy. Actual canal lengths of 30 extracted teeth were determined under magnification. An alginate model was used to determine experimental canal lengths with the Root ZX II apex locator (EAL) and size #10 Accufiles and Flexofiles. Differences between actual lengths and experimental lengths were compared with Student's t test. The average experimental lengths were short of the actual length by -0.10 mm (±0.34) and -0.12 mm (±0.16) for the Accufile and Flexofile, respectively with no statistical difference (p > 0.05). SEM images revealed similar non-cutting Batt tips and a square cross-section for the Accufile and triangular for the Flexofile. Both files provided similarly high levels of reliability when used with the Root ZX II EAL.

The Odd One Out: A Comparison of Flower and Fruit Development in Holoparasitic Pholisma arenarium (Lennoaceae, Boraginales) to That in Closely Related Ehretiaceae

Premise of research. Lennoaceae is a small root-parasitic plant family comprising four species in two genera. They are included in Boraginales, but their position within the order has long been questionable. Only recent phylogenomic studies have placed Lennoaceae within Ehretiaceae with highest support. Because of their holoparasitic lifestyle, Lennoaceae are morphologically aberrant, and their morphological evolution is not fully understood. The position of Lennoaceae within Ehretiaceae invites a study of their development and morphology in comparison to closely related species of that family. Methodology. We investigate the flower and fruit development of Pholisma arenarium from the Lennoaceae and two species from Ehretiaceae (Bourreria succulenta and Ehretia dicksonii) using scanning electron microscopy and micro–computed tomography. Pivotal results. The three species share a number of common morphological and architectural features. Most noteworthy are the absence of a stylar compitum and the formation of false septa, which are involved in pyrene formation. Pholisma arenarium and B. succulenta share more similarities with each other than with E. dicksonii. Conclusions. Our findings are in line with recent phylogenomic analysis and underscore that Lennoaceae should not be treated as a separate family. Aberrant fruit morphology of P. arenarium appears to be driven by its holoparasitic lifestyle, but fruit anatomy clearly reflects a position in Ehretiaceae. Increased seed production is ensured by carpel multiplication as an obvious escape route to the evolutionary dead end of seed and pericarp integration. Changes in merosity of the outer floral organs are a result of an increased floral apex size.

Treatment options for dens in dente: state-of-art literature review

Background. Dens in dente represents developmental anomaly of tooth structure, characterized with different depth of invagination lined with either enamel or cementum, and associated with different clinical and roentgenological features.
 Objective. To methodize available treatment options for dens invaginatus in systematic manner and analyze suitability of such for different clinical scenarios.
 Materials and Methods. Aggregation of data regarding treatment options for dens invaginatus cases was provided through literature search within Pubmed Central and PubMed databases. Literature review was provided in accordance to the available guidelines.
 Results. Provided literature review helped to establish four main strategies of treating teeth with present dens invaginatus anomaly:1) preventive treatment (with no endodontic intervention);2) preventive treatment (with endodontic intervention only in invaginated canal);3) treatment of dens invaginatus-associated complications (with endodontic treatment of original and invaginated canals);4) complex treatment of dens invaginatus-associated complications, which includes not only root canal treatment, but also periodontal treatment and other potential treatment options, such as extraction.
 Conclusion. Dens invaginatus represents several clinical challenges during the treatment related with type of structural anomaly due to the Oehlers classiŢcation, variability of its conŢguration, depth of invagination and its localization within coronal or root portion of tooth, proximity to the pulp and pretreatment pulp and periodontium vitality conditions, while also with periapical status in means of apex size and thickness of root residual walls.

Application of a 3D printed miniaturized hydrocyclone in biopharmaceutical industry-numerical and experimental studies of yeast separation from fermentation culture media

Various industries ranging from water purification to pharmaceutical production have experienced multi separation steps that impose more process time and contamination possibility by batch operation. We propose a developed microfluidic particle sorter (miniaturized hydrocyclone) that adopts centrifugal force as it has ability to decline the number of separation steps and the risk of extrinsic contamination in continuous process. While biological industries have not relied on mini hydrocyclones considerably because of low efficiency and microfabrication difficulties, current work has been planned to conquer these obstacles. In this research, biomass separation from fermentation broth by 3 mm hydrocyclones was investigated. The effect of apex size, feed flow rate, hydrocyclone geometry were analyzed numerically in four mini-hydrocyclones. The most efficient mini-hydrocyclone was chosen to be made by elegant additive manufacturing technology and studied experimentally. The separation efficiency was achieved up to 90% while the concentration ratio of heavy stream (apex) to dilute stream (vortex finder) was reached more than twofold. The mini hydrocyclone performance in view of energy target was studied by Euler-Reynolds-Efficiency plots. The 4 μm cut size was achieved that is promising high throughput separation for biological particles.

Ultrasonographic Evaluation of the Pyramidal Lobe of the Thyroid Gland in Infants and Children in Western Turkey Between 2018 and 2020

Background: The pyramidal lobe (PL) is a common anatomic variation of the thyroid gland with a reported prevalence of over 50% in adult series, but to the best of our knowledge, there are no data in the literature regarding its characteristics in the pediatric population. Objectives: The aim of this study was to evaluate the prevalence, anatomic, and morphological features of the PL in pediatric participants on thyroid ultrasonography (US). Methods: The descriptive cross-sectional study design was used. Between November 2018 and January 2020, the US images obtained from 325 participants with normal thyroid glands were retrospectively evaluated. The presence, location, size, volume, the morphology of the base, and continuity or separation from the thyroid gland were noted for each PL. Results: The PL was present in 34.1% (110/325) of the pediatric participants. It was more frequent in girls than in boys. In all, 56.4% were found to originate from the left of the midline of the isthmus. One patient had double PL. The mean anteroposterior, transverse, and longitudinal diameters were 2.5 ± 1.4, 2.7 ± 1.3, and 5.6 ± 2.5 mm, respectively. The median volume of the PL was 15.11 mm3. PL was longer in girls compared to boys; however, these changes were not significant (5.8 vs. 5.1, P = 0.406, respectively). A total of 63.6% of the PLs were with a wide base and narrow apex, and 36.4% were with a thin base size the same as the apex size. A separation of the PL from the thyroid was not observed. Conclusion: The present study showed, for the first time, that the age of the children is positively correlated with the size and volume of the PL. The prevalence and location of the PL were consistent with those reported in the adult population.

Improvement of spatial resolution by tilt correction in near-field scanning microwave microscopy

The limitation of mechanical manufacturing will result in a small tilt angle of the sample stage in the horizontal direction, which decreases the spatial resolution of imaging in near-field scanning microwave microscopy (NSMM). In this paper, we focus on the tilt correction and improve the spatial resolution of the NSMM image. The results of electromagnetic simulation and line scan measurement demonstrate the critical parameters affecting the sensitivity of NSMM, such as the length of the probe extending out of the cavity, the tip–sample distance, and the tip apex size. The tilt images can rotate successfully to the horizontal plane with the tilt correction methods, and the local average and re-interpolation are applied to denoise the images. Experimental NSMM images of copper thin film grid, coin texture, lithography mask, and leaf vein are obtained. The images before and after correction verify the improvement of the spatial resolution with all the above methods.

The Effect of Different Dominant VRN Alleles and Their Combinations on the Duration of Developmental Phases and Productivity in Common Wheat Lines

Using allele-specific primers and hybridological analysis, the allelic composition of the VRN and PPD loci was determined in common wheat lines derived from the Bezostaya 1 (Bez1) cultivar. In lines of the Bez1 cultivar carrying different dominant alleles of the VRN genes and their combinations, the duration of certain developmental phases was examined. It was demonstrated that, in lines with the combination of two dominant alleles of the VRN-1 locus (Bez1Vrn-A1aVrn-B1a and Bez1Vrn-A1aVrn-B1c), the duration of the “tillering–first node” and “shoots–heading” periods was statistically significantly decreased compared to the initial isogenic lines (i:Bez1Vrn-A1a, i:Bez1Vrn-B1a, and i:Bez1Vrn-B1c). In addition, the presence of two dominant alleles led to the reduction in the time span of the organogenesis stages, as shown by studying the dynamics of shoot apex size and morphology in common wheat lines of the Bez1 cultivar. The productivity analysis in the lines of the Bez1 cultivar showed that the i:Bez1Vrn-B1c line was characterized by highest productivity among isogenic lines, while the Bez1Vrn-A1a Vrn-B1c line was more productive than the Bez1Vrn-A1a Vrn-B1a line.

Developmental basis for flower sex determination and effects of cytokinin on sex determination in Plukenetia volubilis (Euphorbiaceae)

Key messageCytokinin might be an important factor to regulate floral sex at the very early stage of flower development in sacha inchi.Sacha inchi (Plukenetia volubilis, Euphorbiaceae) is characterized by having female and male flowers in a thyrse with particular differences. The mechanisms involved in the development of unisexual flowers are very poorly understood. In this study, the inflorescence and flower development of P. volubilis were investigated using light microscopy and scanning electron microscopy. We also investigated the effects of cytokinin on flower sex determination by exogenous application of 6-benzyladenine (BA) in P. volubilis. The floral development of P. volubilis was divided into eight stages, and the first morphological divergence between the male and female flowers was found to occur at stage 3. Both female and male flowers can be structurally distinguished by differences in the shape and size of the flower apex after sepal primordia initiation. There are no traces of gynoecia in male flowers or of androecia in female flowers. Exogenous application of BA effectively induced gynoecium primordia initiation and female flower development, especially at the early flower developmental stages. We propose that flower sex is determined earlier and probably occurs before flower initiation, either prior to or at inflorescence development due to the difference in the position of the female and male primordia in the inflorescence and in the time of the female and male primordia being initiated. The influence of cytokinin on female primordia during flower development in P. volubilis strongly suggests a feminization role for cytokinin in sex determination. These results indicate that cytokinin could modify the fate of the apical meristem of male flower and promote the formation of carpel primordia in P. volubilis.

Usefulness of apical area index to predict left ventricular thrombus in patients with systolic dysfunction: a novel index from cardiac magnetic resonance

BackgroundLV systolic dysfunction presents an elevated risk of thromboembolism. Previous studies demonstrated low left ventricular ejection fraction (LVEF), ischemic cardiomyopathy and increased myocardial scarring as independent risk factors for LV thrombus formation. Structural changes that alter the size and shape of LV apex may have a significant role in predicting LV thrombus, but there is no definite evidence exists in this entity.MethodsA case-control cardiac magnetic resonance (CMR) study of 150 patients with LV systolic dysfunction (LVEF < 40%; 30 patients with LV thrombus and 120 patients without thrombus) was performed. Factors associated with thrombus including sphericity index and ‘new’ apical area index (ratio of apical area to entire LV area from a cine four-chamber view) were evaluated.ResultsAverage age was 63.48 ± 12.82 years and mean LVEF was 29.22 ± 8.53%. Patients with LV thrombus had significantly higher apical area index than those without thrombus (46.5 ± 3.27 vs. 42.71 ± 3.02, p < 0.001) while sphericity index in both groups was not different (1.63 ± 0.27 vs. 1.67 ± 0.19, p = 0.57). Univariate analysis revealed that male gender, prior myocardial infarction, presence of apical aneurysm, ischemic-typed scar, apical scar and apical area index were associated with thrombus. Further, multivariate analysis showed only apical area index and apical scar as independent predictors for thrombus formation.ConclusionApical area index from CMR is a new index to predict LV thrombus in patients with LV systolic dysfunction and may have a future role in early anticoagulant therapy.

Fabrication and characterization of a focused ion beam milled lanthanum hexaboride based cold field electron emitter source

We report on a method of fabricating lanthanum hexaboride (LaB6) cold field emission tips with sub-100-nm apices by using a combination of electrochemical etching and focused ion beam milling. The primary advantage of combining the two methods is rapid fabrication while maintaining reproducibility. The LaB6 tips have low work functions and high mechanical stabilities and are chemically inert to residual gases. Field emission characterization was performed on three tips, with apex sizes of 15, 85, and 80 nm yielding 10 nA cold field emission currents at 0.76, 3.9, and 3.6 kV extraction potentials, respectively. All three tips showed excellent emission current stability for periods exceeding 30 min in a 5 × 10−9 mbar vacuum.

Asparagus bojnurdensis (Asparagaceae), a new species from Iran

Asparagus bojnurdensis is described as a new species from the North-East of Khorasan province. The new species is compared with its closest relative A. verticillatus. It is similar to A. verticillatus in having unequal cladodes, branched stem, cladode with acute apex, cladode straight and scale leaves. A. bojnurdensis is also similar to A. khorasanensis in having unequal cladodes, branched stem, cladode with acute apex, spur and berry size. Further information on the species, their morphology, micromorphology, habitats and distribution is also provided.

Comparison of prostate contours between conventional stepping transverse imaging and Twister-based sagittal imaging in permanent interstitial prostate brachytherapy.

PurposeTo compare prostate contours on conventional stepping transverse image acquisitions with those on twister-based sagittal image acquisitions.Material and methodsTwenty prostate cancer patients who were planned to have permanent interstitial prostate brachytherapy were prospectively accrued. A transrectal ultrasonography probe was inserted, with the patient in lithotomy position. Transverse images were obtained with stepping movement of the transverse transducer. In the same patient, sagittal images were also obtained through rotation of the sagittal transducer using the “Twister” mode. The differences of prostate size among the two types of image acquisitions were compared. The relationships among the difference of the two types of image acquisitions, dose-volume histogram (DVH) parameters on the post-implant computed tomography (CT) analysis, as well as other factors were analyzed.ResultsThe sagittal image acquisitions showed a larger prostate size compared to the transverse image acquisitions especially in the anterior-posterior (AP) direction (p < 0.05). Interestingly, relative size of prostate apex in AP direction in sagittal image acquisitions compared to that in transverse image acquisitions was correlated to DVH parameters such as D90 (R = 0.518, p = 0.019), and V100 (R = 0.598, p = 0.005).ConclusionsThere were small but significant differences in the prostate contours between the transverse and the sagittal planning image acquisitions. Furthermore, our study suggested that the differences between the two types of image acquisitions might correlated to dosimetric results on CT analysis.

Tip convolution on HOPG surfaces measured in AM-AFM and interpreted using a combined experimental and simulation approach

Amplitude modulated atomic force microscopy (AM-AFM) was used to examine the influence of the size of the AFM tip apex on the measured surface topography of single highly oriented pyrolytic graphite (HOPG) atomic steps. Experimental measurements were complemented by molecular dynamics simulations of AM-AFM and the results from both were evaluated by comparison of the measured or simulated width of the topography at the step to that predicted using simple rigid-body geometry. The results showed that the step width, which is a reflection of the resolution of the measurement, increased with tip size, as expected, but also that the difference between the measured/simulated step width and the geometric calculation was tip size dependent. The simulations suggested that this may be due to the deformation of the bodies and the effect of that deformation on the interaction force and oscillation amplitude. Overall, this study showed that the resolution of AM-AFM measurements of atomic steps can be correlated to tip size and that this relationship is affected by the deformation of the system.

Nerve injury induced activation of fast-conducting high threshold mechanoreceptors predicts non-reflexive pain related behavior

The role of specific subsets of peripheral nerves in pain related behavior remains unclear. To better understand the contribution of differential activation of fast-conducting, high-threshold mechanoreceptor (AHTMR) input, we hypothesized that neuronal activation would be distinct with nerve injury, and that nociceptive input would predictt behavior in the freely exploring animal. A series of surfaces was used to deliver mechanical input to the hindpaws of rats upon voluntary movement and exploration. Neuronal activation increased as apex surface decreased (0.2, 0.6, 1.0 and 1.5mm) using in vivo recording in L4 DRG neurons, and this relationship was enhanced following partial ligation of L5 (pSNL). In behaving animals, apex size was correlated to time spent on each surface following pSNL, but not with sham. Morphine normalized the discriminatory behavior following pSNL. These data indicate that noxious mechanical activation of AHTMR upon normal movement predicts behavior using paradigms that do not rely on reflexive withdrawal responses suggesting that AHTMR activation and central nervous system input contribute to higher order pain behavior after nerve injury beyond the immediate early pain input long attributed to these neurons.

Subdiffraction‐limited chemical imaging of patterned phthalocyanine films using tip‐enhanced near‐field optical microscopy

A tip‐enhanced near‐field optical microscope, based on a shear‐force atomic force microscope with plasmonic tip coupled to an inverted, confocal optical microscope, has been constructed for nanoscale chemical (Raman) imaging of surfaces. The design and validation of the instrument, along with its application to near‐field Raman mapping of patterned organic thin films (coumarin‐6 and Cu(II) phthalocyanine), are described. Lateral resolution of the instrument is estimated at 50 nm (better than λ/10), which is roughly dictated by the size of the plasmonic tip apex. Additional observations, such as the distance scaling of Raman enhancement and the inelastic scattering background generated by the plasmonic tip, are presented. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Effect of apex size on the leakage of gutta-percha and sealer-filled root canals.

There are no data comparing coronal leakage of teeth prepared to different apical sizes and obturated with gutta-percha and sealer. The aim of this study was to investigate the effect of apical preparation size on the leakage of obturated root canals. Large apical openings are encountered as a result of pulp necrosis in immature teeth, apical resorption, or over-enlargement of the apical foramen. Complete cleaning, shaping, obturation, and apical seal of root canal systems are essential for the success of root canal treatment. One hundred twenty-five extracted human teeth were divided into groups containing 25 samples each and prepared to apical file sizes 30, 40, 50, 60, and 70. Twenty teeth served as positive and negative controls. Obturation was completed with gutta-percha and sealer via warm vertical compaction. Bacterial leakage was investigated after 112 days using Proteus vulgaris. Data were analyzed via independent-samples Kruskal-Wallis test. The average time for leakage of apical preparation sizes 30, 40, 50, 60, and 70 were 57.5, 52.4, 47.2, 37.5, and 28.4 days, respectively. Significant differences in leakage were observed between apical preparation sizes 70 versus 30, 70 versus 40, 70 versus 50, as well as 60 versus 30. A trend for more leakage occurred when apical preparation sizes exceeded size 60. Based on these results, it appears leakage of gutta-percha and sealer as obturation materials increases when apical preparation size exceeds 60. Consideration should be given to using sealing materials other than gutta-percha and sealer when the apex size exceeds 60.

Enhancement Effects of the Terahertz Near-Field Microscopy

Terahertz near-field detection based and imaging on a nanotip has drawn wide attention following extensive applications of terahertz imaging technologies. Through the local enhanced electric field created by a terahertz nanotip in the near field, it is very likely to attain superior detection sensitivity and higher spatial resolution. This paper simulates the local enhancement effects of the terahertz near-field microscopy using a two-dimension finite difference time domain (2D-FDTD) method. Factors that influence the enhancement effects are investigated and analyzed in detail. Simulation results show that the size of the nanotip apex, the apex-substrate distance, dielectric properties of the substrate and the detected sample, etc., have significant impacts on the electric field enhancement and spatial resolution of the terahertz near-field nanotip, which can be explained from the effective polarizability of the nanotip-sample/substrate system.

Investigation of enhancement of near-field probing for sensing at terahertz waveband

Enhancement of localized surface plasmon resonance (LSPR) for near-field probing working at terahertz waveband is an important issue. Optimization of an apertureless metallic probe is presented for the purpose of sensing and detection in high resolution. Numerical calculation is carried out for the purpose of design and optimization of the probe. Corresponding results demonstrate that performance enhancement of the probe at terahertz waveband is different from that of the visible regime. Unlike the visible case that the smaller size of the probe apex results in stronger LSPR, actually, it is opposite to the case of visible for the terahertz regime while the size of probe apex d is ranging from 0 to 20nm. The enhancement of the probe working at terahertz regime is mainly dominated by surface effect. In addition, the numerical results give a proof again that exciting SPP enhanced LSPR signal at near-field for the terahertz wavelength is surely difficult than that of the visible case.