Average Radius Of Curvature Research Articles

Poster 173: Evaluation of Radius of Curvature of the Humeral Capitellum in Young Athlete Osteochondritis Dissecans Lesion Sites

Objectives: Elbow Osteochondritis dissecans (OCD) lesions are often seen in young baseball players and gymnasts. Prior studies have suggested that capitellar OCD lesions are frequently found in two distinct and separate locations in these two populations: at 58° and 28° inclination angles from the humeral axis in baseball players and gymnasts respectively. As treatment of OCD lesions with osteochondral allografts and autografts have gained popularity, an increased emphasis has been placed on the utilization of measurements of capitellar radius of curvature (ROC) to minimize articular incongruity or ROC mismatch between the recipient elbow and donor knee. The purpose of this study was to further characterize the coronal-axial ROC in these two distinct locations and potentially identify morphological differences between the two OCD lesion locations. Methods: Elbow MRIs of thirty pediatric patients between the ages of eight and seventeen with no history of elbow injuries were retrospectively studied. Using the radiographic diagnostic viewing software, eUnity, two reviewers measured capitellar ROCs encompassing at least a ten-millimeter plug at both 58° and 28° inclination angles from the humeral axis on coronal-axial elbow MRIs for each patient. Coronal-axial views were established by using the 3D function to orient the axial plane in parallel with the capitellar articular surface and the coronal plane perpendicular to the capitellar surface. 58° and 28° inclination angles from the humeral axis were measured in the sagittal plane, and coronal-axial images were transformed in phase with each inclination angle. For each observer, paired two-tail t-tests were performed to evaluate statistical differences in ROC measurements between the two locations. Inter-observer absolute agreement was examined using the “irr” Intraclass Correlation Coefficient R package. Using a Fisher’s test, p values from the individual observer paired t-tests were combined and reviewed. Results: The Intraclass Correlation Coefficients were 0.886 for the 58° inclination angle and 0.921 for the 28° inclination angle, respectively denoting good and excellent inter-observer reliability. Paired two-tailed t-tests of each observer’s 58° and 28° capitellar ROC measurements yielded p<0.001. The unweighted average t-value of 10.49 with 29 degrees of freedom and the combined Fisher p-value of <0.001 suggest there is a significant difference between the ROC measurements at the 58° and 28° humeral capitellar locations. Average ROC measurements ranged between 13.94mm ± 1.31mm and 14.3mm ± 1.42mm at the 58° capitellar location and 11.7mm ± 1.53mm and 11.76mm ± 1.30mm at the 28° capitellar location. Measurements at the 28° inclination angle from the humeral axis tended to be smaller than those of the 58° inclination angle from the humeral axis. On average the ROC at the 28° inclination was between 2.18mm and 2.50mm smaller than the ROC at the 58° inclination. Conclusions: Prior studies have identified differences in capitellar OCD lesion location between baseball players and gymnasts. This study offers further characterization of both morphologic locations. The capitellar radii of curvature at 58° and 28° inclination angles from the humeral axis statistically differed, as demonstrated by both observer measurements. The ROC at the 28° inclination was on average between 2.18mm and 2.50mm smaller than the ROC at the 58° inclination. Therefore, because of evident ROC differences between these two locations, it may be beneficial to consider anatomic morphologic differences between distinct humeral capitellum regions when selecting graft locations to achieve an optimal osteochondral autograft match. Future research on optimizing donor-to-recipient ROC may improve articular congruity restoration and long-term outcomes.

Corneal topographic indices of Scheimpflug camera in type 2 diabetic and non‐diabetic elderly population

Aims/Purpose: To determine the corneal topographic indices of Scheimpflug camera in type 2 diabetic and non‐diabetic in elderly population of Tehran, Iran.Methods: A total of 1105 subjects were selected using random cluster sampling from Tehran, Iran and categorized into two groups including diabetics and non‐diabetics. The diabetic group had HbA1c levels ≥6.4% with no other systemic problems. The non‐diabetic participants had normal eye findings and no systemic diseases. The keratometry values, Q‐value, index of surface variance (ISV), index of vertical asymmetry (IVA), central keratoconus index (CKI), keratoconus index (KI), index of height asymmetry (IHA), index of height decentration (IHD), anterior average radius of curvature (ARC), posterior average radius of curvature (PRC), and pachymetric progression index (PPI) values were measured using the Pentacam AXL.Results: A total participants included 429 diabetic (38.46% male) and 676 non‐diabetic (38.76% male). Only PPIavg and PPImax were higher in the diabetics versus non‐diabetics (p = 0.019 and p = 0.010, respectively). The HbA1c level was 5.47 ± 0.34, 6.70 ± 0.17, and 8.72 ± 1.16 in the first, second, and third group, respectively. There was a significant difference in PPImax between the three groups (p = 0.036). There were significant differences only in IVA, CKI, PPIAvg, and PPImax between different stages of DR (p = 0.045, p = 0.005, p = 0.002, and p = 0.004, respectively). The diabetic subjects were divided into two groups based on the presence of DR. There was a significant difference in ISV, IVA, PPIavg, and PPImax between diabetic subjects with and without DR (p = 0.016, p = 0.022, p < 0.001, and p < 0.001, respectively).Conclusions: The results of this study showed that DM and DR change several topographic indices and the HbA1c level may affect PPImax. Therefore, special attention should be paid to these patients for different treatment strategies.

Modelling of longitudinally cut carrot curling induced by the vascular cylinder-cortex interference pressure.

Cut carrot pieces are popular convenience foods, which enable the use of misshapen or physiologically imperfect produce. Cut carrots curl due to residual stress, which limits their shelf life and causes unnecessary food waste. The aim of this study is to identify the geometrical and environmental factors which have the most influence on their longevity. An analytical equation was developed using compound cylinder solutions, and this was used to define carrot-specific finite element (FE) models. Over 100 longitudinally cut Lancashire Nantes carrot halves were characterized, each was modelled analytically and verified using FE models. This model was evaluated by comparing predicted curvatures to ones experimentally measured over a week. The average radius of curvature decreased from 1.61 to 1.1 m a week after. A 1.32× reduction in the elastic modulus after 7 days was observed. The moisture content reduction relates to 22% weight loss, correlating to the decreasing radius of curvature. Subsequently, carrots are recommended to be stored in humidity-controlled environments. The experimental results from this study match the predictions made using mechanical principles. The research provides a methodology to predict the deformation of cut root vegetables, and the procedure is likely to be applicable to other plant structures.

Paper 02: Distal Radius Allograft for Glenohumeral Instability: A Novel Osteochondral Allograft Reconstruction Option in the Setting of Glenoid Bone Loss

Objectives: Glenoid bone loss in the setting of recurrent shoulder instability remains a challenging surgical problem. The coracoid process and iliac crest currently serve as primary autograft options for glenoid reconstruction. With regards to allograft alternatives, the distal tibia, first described in 2007, has good midterm outcomes when used during an index surgery and in cases of failed prior Latarjet reconstruction. While the distal tibia performs well in reconstructing the glenoid bony defect, it is a nonanatomic reconstruction and does not match the glenoid radius of curvature (ROC) in the anterior to posterior (AP) plane. No prior work has evaluated and described the utilization of the dorsal articular portion of the distal radius as an allograft reconstruction option for recurrent instability with glenoid bony deficiency. The purpose of this study was to evaluate distal radius fresh frozen allograft as a potential match for glenoid reconstruction through assessment of graft ROC and bone mineral density (BMD). Distal tibia allograft was utilized as the primary comparison group with both cadaveric and Computerized Tomography (CT) analysis. Methods: Eighteen fresh-frozen human cadaveric specimens (6 shoulder, 6 wrist, and 6 tibia) were utilized for this study. Specimens without osteoarthritis or prior surgical procedures were included. CT scans were obtained of all specimens to confirm the absence of osteoarthritis, significant joint deformity, or evidence of prior surgical procedure. Specimens were dissected free of all soft tissues except for the glenoid labrum of the shoulder and dorsal wrist ligaments of the distal radius. The ROC for each specimen were independently measured by two fellowship trained shoulder surgeons in both the superior to inferior (SI) and AP planes. Graft length in the SI plane was also assessed. A thirty percent defect was then created in all glenoid specimens and both distal tibia and distal radius grafts were harvested to assess graft fit post-fixation [Figure 1]. CTs were also analyzed to assess bony ROC and BMD for each specimen. Results: On cadaveric analysis, the mean SI graft length of the glenoid was 39.7 mm compared to 36.8 mm for the distal radius and 30.0 mm for the distal tibia [Table 1A]. Average ROC in the SI plane was 29.0 +/- 5.3 for the glenoid, 37.8 +/- 4.9 for the distal radius and 24.0 +/- 3.7 for the distal tibia; in the AP plan average ROC was 39.6 +/- 6.6 for the glenoid, 30.4 +/- 18.6 for the distal radius and 126.3 +/- 9.5 for the distal tibia [Table 1B]. On CT analysis, average ROC in the SI plane was 30.4 +/- 1.5 for the glenoid, 30.3 +/- 5.6 for the distal radius and 24.5 +/- 9.4 for the distal tibia; in the AP plane average ROC was 30.8 +/- 2.0 for the glenoid, 19.1 +/- 2.3 for the distal radius and 46.7 +/- 21.7 for the distal tibia [Table 2A]. Mean BMD was 226.3 +/- 79.0 for the glenoid, 228.5 +/-94.7 for the distal radius, 235.0 +/- 96.2 for the coracoid process, and 235.1 +/- 84.6 for the distal tibia [Table 2B]. Conclusions: Given fresh frozen allograft supply and cost constraints, exploration of additional graft options is necessitated. This study presents distal radius allograft as a novel reconstruction option for patients with anterior glenoid bone loss in the setting of recurrent glenohumeral instability. Compared with the distal tibia allograft, the distal radius had greater graft length in the SI plane providing possible utilization in cases of larger bony defects. The distal radius also has a more acute ROC in the AP plane (closer to that of the glenoid) compared with the distal tibia allograft providing a greater potential buttress to anterior humeral translation. Furthermore, the distal radius also has potential to employ the dorsal radio-carpal ligaments to perform an anterior capsular repair following allograft fixation. Finally, compared to currently utilized grafts (coracoid process and distal tibia), the distal radius BMD was not significantly diminished on CT analysis. This study presents the distal radius as a novel allograft reconstruction option in the setting of glenoid bone loss; further biomechanical and clinical investigation is indicated. [Table: see text][Table: see text]

QUANTITATIVE LAWS OF A MORPOLOGICAL PATTERN FOR ABRASION SLOPES WITN A LANDSLIDE PROCESS WITHIN THE CRYOLITHOZONE (THE COASTS OF THE KANIN AND YAMAL PENINSULAS AS EXAMPLES)<a href="#FN1"><sup>1</sup></a>

Coast landslide processes take a special place in the study and monitoring of processes in permafrost under the climate change, however, not much attention has been paid to the morphology and quantitative characteristics of the landslides. The aim of the work is to reveal quantitative relationships between the abrasion slopes and a landslide process for coasts within the cryolithozone, mainly in contact with the adjacent interfluves. The research is based on the interpretation of high-resolution space imagery at five costal sites of the Kanin and Yamal peninsulas. The study was focused on the morphological features of the upper part of the landslides at the border with the adjacent interfluve. This border is a combination of arc elements. Besides, there are arcuate residual sections of the interfluve surface, corresponding to different stages of landslide process, in some places on the slope. Analysis of the coastline from images gave us such characteristics of landslides as the length of the arcs forming the boundary, the length of the chords of the arcs, the arrows of the arcs, the average radii of curvature, the central angles of the arc, the angles of orientation of the chords with respect to the vector of the general strike of the corresponding section of the coastline. Some of these characteristics were obtained by direct measurement from satellite images, the others by calculation. The analysis included 30 samples with a volume of 103–183 elements. Statistical processing using Pearson’s goodness-of-fit test showed that in the vast majority of the sites, the distributions of the landslide upper boundary arc sizes, chords, arc arrows, and curvature radii, as well as central angles, correspond to a lognormal one. The chord orientations with respect to the strike of the site are normally distributed. The values of the distribution parameters of the studied quantitative characteristics of the landslide morphological features differ and depend on the physical-geographical and engineering-geocryological conditions of specific areas.

What in particle morphology determines the DLVO interaction energy between hematite particles in electrolyte solutions?

The experimental stability of hematite particles (radius: ∼74 nm) dispersed in solutions of varying salinity deviates considerably from predictions based on the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. For untreated hematite particles, at pH = 6 and 10, the theoretical values could be matched to the experimental ones by modifying the particle radius used in calculations from 74 to 13 nm. For particles heat-treated at 350 °C for 1 h, the theoretical values at pH = 10 could also be matched to the experimental ones by modifying the particle radius to 7 nm. Atomic force microscopy measurements revealed that the radius of curvature for surface protrusions on the hematite particles was 14 nm on average for the untreated particles at pH = 6 and 10, which almost equals the aforementioned modified particle radius. For the heat-treated hematite particles at pH = 10, the average radius of curvature was 9 nm, which also matched the corresponding modified particle radius. Therefore, we argue that the interaction energy between hematite particles is governed by not the overall particle radius but the curvature radius for surface protrusions. This could account for the discrepancy between theory and experiment regarding the salinity-dependent stability ratio of these particle dispersions.

Interest in curves: when the radius of curvature matters in femur fractures. A CT based morphometric study.

In today's era, fractures of the femur are primarily managed with intramedullary devices. Keeping in mind the anatomical sagittal bow of the femur, intramedullary devices have been devised with an anterior bow, but this varies amongst various manufacturers - leading to complications such as anterior cortex impingement beyond the isthmus and posterior cortical opening at the fracture site. We intend to find the average radius of curvature (ROC) of the anatomical bow of the femur and the variation of the same. Radiographic data of 150 normal femur scans done in 81 patients were loaded in the Mimics 21.0 software (Materialise, Leuven, Belgium). A centerline (of the medullary cavity) was created using the software. A best-fit circle was created in the sagittal plane involving a major part of the centerline, and ROC was calculated. We found the average ROC of our data was 1027.2, with a standard deviation of 241.55. ROC and length of the femur (an indirect measure of height) had a slight positive correlation (r = 0.36; p < 0.05); and a highly positive correlation in the ROC of the left and right femurs of the same individuals (r = 0.605; p < 0.05). The usual ROC of intramedullary nails is commonly > 1300mm, much higher than the average ROC we identified in our population. Thus, we conclude that implants with smaller ROC in the range of 1100mm are needed, leading to better implant placement in the canal and avoiding complications of anterior cortex impingement and preventing fracture gap widening in our setting.

Progress in Near-Equilibrium Ammonothermal (NEAT) Growth of GaN Substrates for GaN-on-GaN Semiconductor Devices

This paper reviews the near-equilibrium ammonothermal (NEAT) growth of bulk gallium nitride (GaN) crystals and reports the evaluation of 2″ GaN substrates and 100 mmbulk GaN crystal grown in our pilot production reactor. Recent progress in oxygen reduction enabled growing NEAT GaN substrates with lower residual oxygen, coloration, and optical absorption. The oxygen concentration was approximately 2 × 1018 cm−2, and the optical absorption coefficient was 1.3 cm−1 at 450 nm. Maps of full-width half maximum (FWHM) of X-ray diffraction rocking curveswere generated for grown crystals and finished wafers. The X-ray rocking curve maps confirmed high-quality and uniform microstructure across the entire surface of the bulk crystals and substrates. The average FWHM of the 50 best bulk crystals from the recent batch was 28 ± 4 arcsec for the 002 diffraction and 34 ± 5 arcsec for the 201 diffraction, with an average radius of curvature of 20 m. X-ray topography measured on both sides of the bulk crystals implied that the density of dislocations wasreduced by one order of magnitude during the NEAT growth. A typical NEAT GaN substrate shows dislocation density of about 2 × 105 cm−2.

Study of turbulent flame characteristics of water vapor diluted hydrogen-air micro-mixing combustion

Hydrogen has been regarded as an important alternative fuel, especially in gas turbine applications. However, the premixed combustion of pure hydrogen has problems such as easily flashback and high NOx emissions. A more reasonable method of combustion is to use micro-mixing technology combined with water vapor dilution. This work experimentally investigated the influences of dilution rate (D) and equivalence ratio (φ) on the flame characteristics of hydrogen-air micro-mixing combustion diluted with water vapor. Results show that increasing D reduces the flame area by reducing the downstream OH radical signal, which is contrary to the effect of CO2 dilution. The flame local curvature radius shows that the micro-mixing combustion is a high turbulence intensity combustion, and the convex structure is more frequent. Moreover, increasing φ or decreasing D leads to a decrease in the instantaneous average curvature radius (Rave), indicating more small-scale wrinkle structures are generated. D and φ have a similar influence on the fluctuations of Rave and flame area in the time domain, while the fluctuation of the flame area is more evident near the lean-burn limit. When D = 25%, the frequency characteristics of the flame structure and chemical reactions are synchronized.

Experiment on fluid regime under different rotate velocity in physical simulation of titanium vertical centrifugal casting

In this paper, the physical simulation of filling process of vertical centrifugal casting (VCC) of complex titanium alloy casting was studied. Combined with the mature PTV particle tracking technology, the high-speed photography pictures of the filling process of VCC at different rotational speeds were obtained. The trajectory and velocity information of tracer particles in the rotating flow field were obtained by the corresponding analysis software. Then, through the analysis and modeling of quantitative experimental data, the flow behavior characteristics and movement law of titanium alloy melt in the mold cavity under different mold speeds were studied. The results show that: 1. When the mold is still, the front edge of the filling fluid forms a curved surface with the curvature center pointing to the outside of the mold; when the mold rotates, the front edge of the liquid flow forms a curved surface with the curvature center pointing to the inside of the mold; 2. With the increase of the mold rotation speed, the speed of the fluid filling the mold increases significantly; when the rotational speed is greater than 120 rpm, the fluid still has a certain driving force in the mold center far away from the gate; it is good for filling the inner corner of mold with fluid; and 3. When the rotational speed of centrifugal casting of titanium alloy reaches 45 rpm or above, typical turbulent vortices appear in the wake; with the increase of rotating speed to 180 rpm, the average curvature radius of turbulent vortices first increases and then decreases, and reaches the minimum value of 0.67 cm at 120 rpm.

Optimizing Graft Extraction From the Femoral Condyle for Fresh Osteochondral Allograft Transplantation in Treating Osteochondritis Dissecans of the Capitellum: Best Fit Based on Radius of Curvature.

Osteochondritis dissecans (OCD) of the capitellum is a common cause of pain and dysfunction in adolescents that engage in repetitive elbow loading. For large, unstable lesions fresh osteochondral allograft transplantation (FOCAT) from the femoral condyle has been described as an effective treatment. Current practice involves significant guesswork in obtaining an appropriately sized graft, with anatomic variations resulting in poor graft fit. No studies currently exist that analyze and identify the best distal femur FOCAT graft site to repair OCD lesions of the capitellum based on the radius of curvature (ROC) and simulated matching. Computed tomography scans of the elbow were used to estimate the subchondral bone ROC of capitella in adolescents aged 11 to 21 years. The capitellar location used corresponds to the most commonly reported site of OCD lesions in the elbow. Computed tomography scans of the lower extremity were used to estimate the subchondral bone ROC of 4 potential donor femoral condyle grafts. ROC from distinct regions at the posterior section of both the medial and lateral femoral condyles were measured: 2 areas representing 10 mm grafts from the center (MC1 and LC1), and 2 areas estimating 10 mm grafts posterior and adjacent to the physeal scar (MC2 and LC2). Intraobserver and interobserver reliability measurements were preformed to corroborate precision and validate the method. The mean ROC of healthy subchondral bone at the region of the capitellum were OCD lesions most commonly occur was 9.79±1.39 mm. The mean ROC of MC1 was 18.61±2.26 mm. The average ROC of the MC2 was 15.23±1.43 mm. The average ROC of LC1 was 16.47±1.34 mm. The average ROC of LC2 was 18.19±3.09 mm. After 15,000 simulated condyle-to-capitellar site matchings based on these measurements, a good fit graft was achieved at a frequency of 15%. No site measured from the femoral condyle demonstrated a subchondral ROC that exactly matched the subchondral ROC of the capitellum at the center location where OCD lesions most commonly occur; of the locations measured, a 10 mm section from MC2 demonstrated the closest match. On the basis of this analysis, extracting a graft from MC2 has the potential to further optimize FOCAT fit to the capitellum. Level III.

ИСПОЛЬЗОВАНИЕ В ПРОИЗВОДСТВЕ ЖАРОСТОЙКИХ БЕТОНОВ АЛЮМОСОДЕРЖАЩЕГО НАНОТЕХНОГЕННОГО СЫРЬЯ И ОТХОДОВ УГЛЕОБОГАЩЕНИЯ

In this work, using waste from the chemical industry — aluminum-containing nanotechnogenic raw materials and a fuel and energy complex — coal enrichment based on phosphate binders, heat-resistant concrete with high physical and mechanical properties is obtained. Thanks to the use of orthophosphoric acid as a binder, it was possible to utilize 80-90% of chemical industry waste and coal preparation, which helps to reduce the anthropogenic load on the environment and humans. Studies show that as the grain size decreases, the total size of the interface is increased, the average radius of curvature of the convex sections decreases, their excess surface energy grows, and the distances between the sources and absorbers of vacancies in the system decrease. Experimental studies and rich practical experience in ceramic industries confirm the crucial role of the degree of grinding (or the use of nanoscale raw materials). Due to the action of this factor alone, it is possible in some cases to reduce the required sintering temperature by 50-100 °C or more. The use of industrial wastes in the production of building materials contributes to: a) the utilization of industrial wastes; b) environmental protection; b) the expansion of the raw material base for heat-resistant concrete based on phosphate binders.

Facile and scalable fabrication of Ni cantilever nanoprobes using silicon template and micro-electroforming techniques for nano-tip focused electrohydrodynamic jet printing

Electrohydrodynamic jet (E-Jet) printing is a powerful technique for micro/nanostructure fabrication with high resolution and efficiency. However, conventional E-Jet printing are still limited in printing accuracy and ink adaptability due to the nozzle clogging effect. In this paper, we develop a nano-tip focused electrohydrodynamic jet (NFEJ) method to print high-resolution structures. The Ni cantilever nanoprobes with nanoscale radius of curvature (ROC) on their tips were manufactured by a facile and scalable method using silicon template and micro-electroforming technique. Scanning electron microscope was used to analyse the micromorphology of the silicon template with inverted pyramid pits, which was obtained from anisotropic wet etching of silicon. Electroforming mold was obtained by photolithography and plasma etching which divide the top side of Ni film into isolated cantilever pits. Ni cantilever nanoprobes with an average tip ROC of about 48 nm were achieved by the subsequent micro electroforming process. High-resolution droplets array with an average diameter of about 890 ± 93 nm were printed by the NFEJ printing head equipped with these Ni nanoprobes, which verified the practicality of the developed Ni nanoprobes for NFEJ printing.

The sagittal geometry of the trochlear groove could be described as a circle: an intraoperative assessment with navigation.

The aim of this study was to describe the sagittal geometry of the trochlear groove in patients who underwent primary TKA, based on intraoperative data acquired with a navigation system. Intraoperative navigation data were collected from 110 patients. All operations were guided by a non-image-based navigation system (BLU-IGS, Orthokey Italia Srl). The trochlear groove has been described on the three anatomical planes; in particular, on the sagittal plane the hypothesis has been verified that the acquired points are referable to a circle. Using the data collected during intraoperative navigation, possible correlation between the radius of the trochlear groove and other femur dimension (length, AP dimension) was analyzed; the orientation of the trochlear sulcus with respect to the mechanical axis and the posterior condyle axis was analyzed too, searching for possible correlation between groove alignment (frontal and axial) or groove radius and the hip-knee-ankle (HKA). The average radius of curvature of the femoral trochlea was 25.5 ± 5.6mm; the difference was not statistically significant between the men and women (n.s. p value). No correlation was found between the trochlear groove radius and the femur length (r = - 0.02) or the HKA-phenotypes (r = 0.03) and between the groove alignment and HKA-phenotypes. On axial plane, the trochlear groove was 3.2° ± 4.3° externally rotated, with respect to the posterior condylar axis; on frontal plane, the trochlear groove was 3.9° ± 5.3° externally rotated, with respect to the mechanical axis. In both cases, no statistically significant differences were found between male and female and between left and right limb (p > 0.05). The present study shows that the sagittal plane geometry of the femoral trochlea in patients affected by osteoarthritis could be described accurately as a circle. The acquisition of the trochlear morphology intraoperatively can lead to more anatomically shape definition, to investigate deeper its radius of curvature and geometry. Trochlear shape could be used as landmarks for femoral component positioning, thus customizing the implant design, optimize the outcomes and improving anterior knee pain after TKA. IV.

Fabrication of highly uniform nanoprobe via the automated process for tip-enhanced Raman spectroscopy

Abstract In a tip-enhanced Raman spectroscopy (TERS) system, using a sharp nanotip that comprises a noble metal is critical to attaining high spatial resolution and highly enhanced Raman scattering. A strongly acidic solution is typically used to fabricate gold nanotips in a quick and reliable manner. However, using an acidic solution could corrode the etching system, thereby posing hazardous problems. Therefore, both the corrosion of the etching system and human error induced by the conventional method considerably decrease the quality and reproducibility of the tip. In this study, we significantly increased the reproducibility of tip fabrication by automating the electrochemical etching system. In addition, we optimized the etching conditions for an etchant that comprised a KCl solution to which ethanol was added to overcome the limitations of the acidic etchant. The automated etching system significantly increases the yield rate of tip-fabrication reproducibility from 65 to 95%. The standard deviation of the radius of curvature decreased to 7.3 nm with an average radius of curvature of 30 nm. Accordingly, the automated electrochemical etching system might improve the efficiency of TERS.

Discrimination of Object Curvature Based on a Sparse Tactile Sensor Array.

Object curvature plays an important role in grasping and manipulation. To be more exact, local curvature is a more useful information for grasping practically. Vision and touch are the two main methods to extract surface curvature of an object, but vision is often limited since the complete contact area is invisible during manipulation. In this paper, the authors propose an object curvature estimation method based on an artificial neural network algorithm through a lab-developed sparse tactile sensor array. The compliant layer covering on the sensor is indispensable for fitting the curved surface. Three types (plane, convex sphere, and convex cylinder) of sample and each type of sample including 30 different radiuses (1 mm to 30 mm) were used in the experiment. The overall classification accuracy was 93.1%. The average curvature radius estimating error based on an artificial neural network (ANN) algorithm was 1.87 mm. When the radius of curvature was bigger than 5 mm, the average relative error was smaller than 20%. As a comparison, the sensor array density we used in this paper was less than 9/cm2, which was smaller than the density of human SAII receptors, but the discrimination result was close to the SAII receptors. Comparison with the curvature discrimination ability of the human body showed that this method has a promising application prospect.

Morphology of the Semicircular Canals and Locomotion of Zionodon satanus

Zionodon satanus is a relatively large “insectivore” from the Uinta Formation of Utah, known from associated fragmentary dental, cranial, and postcranial elements. Features of the postcrania, particularly the knee and ankle joints, suggest that this species primarily engaged in swift terrestrial locomotion, but with some climbing and digging capability. Among the cranial fragments of Z. satanus are two petrosal bones preserving portions of the bony labyrinth, particularly the semicircular canals, which are known to vary among extant mammals according to locomotor agility, with more agile animals having semicircular canals with a larger radius of curvature than slower ones. Thus, semicircular canal dimensions can provide insight into locomotion independent of postcranial morphology. Here we compare measurements of the semicircular canals of Z. satanus to other extant and extinct mammals to assess the degree of locomotor agility of this species and compare those results to those obtained by functional analysis of the postcrania.The petrosal bones of the type specimen of Z. satanus were microCT scanned and virtual models of the semicircular canals were extracted with AMIRA 6.5.0 software. One petrosal includes a complete posterior and partial lateral semicircular canal, whereas the other preserves a complete lateral, damaged but complete posterior, and most of the anterior semicircular canal. The height and width of each semicircular canal was measured from the extracted surface models and the radius of curvature was calculated from height and width measurements. The average radius of curvature of the semicircular canals of Z. satanus overlaps with extant mammals of similar body size of “fast” or “medium” agility and lies well outside the range of slow‐moving small mammals. Compared to other fossil “insectivores”, Z. satanus has relatively smaller semicircular canals than Leptictidium from the middle Eocene of Messel, Germany, which has been reconstructed as a bipedal runner and saltator, but larger ones than the North American leptictids Paleictops and Leptictis. These results corroborate observations from the postcranial skeleton, suggesting that Z. satanus likely engaged in frequent, rapid locomotion.

Buckling of Shallow Spherical Concrete Domes under Gravity and Earthquake Loads

Buckling analysis of spherical concrete domes constructed over prestressed concrete tanks subjected to gravity and earthquake load combinations is complex due to the sensitivity of spherical dome buckling to geometric imperfection, the effect of creep and shrinkage on amplifying the deflection of the dome (increasing the radius of curvature of the deformed dome and reducing the buckling resistance), and the geometric and material nonlinearity of the concrete dome. Study of imperfections has shown that imperfections that increase the average radius of curvature in an area the size of an elastic buckle have the highest impact in reducing buckling strength; thus, the problem of buckling of the concrete dome is reducible to the snap-through buckling of a shallow cap equal in size to an elastic buckle of the dome. In this paper, the buckling of a shallow cap subjected to gravity and seismic load combinations is determined using nonlinear geometry, material nonlinearity of concrete (accounting for softening and cracking in tension and microcracking and crushing in compression), and time-dependent creep and shrinkage of concrete. The analysis is performed in three steps: in the first step, the cap is analyzed for gravity loads; in the second step, the cap is analyzed for the effects of creep and shrinkage strains; and in the third step, the earthquake load is applied until the snap-through buckling occurs. The analysis was carried out on a set of domes designed for gravity load combinations alone. These domes cover the extremes of size and rise of the domes that are currently constructed over prestressed concrete tanks. The results show that the majority of existing domes that are not in high-seismicity zones and are designed for gravity load combinations have capacity for earthquake loading. The results are also of value in the design of new domes for load combinations that include earthquake loading.

Experimental and Numerical Modelling of Nonlinear Flow Behavior in Single Fractured Granite

In this study, the hydromechanical behavior was experimentally investigated by conducting fracture geometry evolution-based gas flow tests on single fractured granite. The traditional fracture roughness value (Rp) of a single surface cannot adequately explain the intrinsic permeability in multiple samples. Instead, the permeability is better explained by aperture distribution, and it is positively correlated with the mean aperture size. The permeability is also affected by a combination of contact area and void space under changing confining stress. The average embedded depth increases rapidly under low-loading stress (less than 8 MPa) and slowly under high-loading stress (higher than 8 MPa). A simplified Hertz contact model was used to fit the experimental data. The model uses the reciprocal of the standard deviation of the aperture as the average curvature radius of the fracture. Good agreement was found between the experimental and theoretical results. A modified smooth parallel-plate model to describe flow friction in fractures was developed, which takes fracture contact and void space into account. A new friction model was also developed that takes both the nonlinear effect and the influence of fracture relative roughness into account by multiplying the ideal model by two power-law functions. This new model is effective in predicting the friction factor. Finally, taking into consideration the built permeability, mechanical, and friction models, a nonlinear flow model was proposed. The flow rate can be estimated based on the 3D fracture topography data, the applied loading stress, and the pressure gradient. The influence of four types of aperture distribution on the friction factor was investigated. The results showed that a high mean aperture size would result in a low friction factor. In addition, the influence of the mean aperture size on the friction factor is obvious, even under a very high-loading stress while the effect of the standard deviation is negligible when the loading stress is very high.

Dynamics of quantized rings and loops after reconnection in superfluid helium

The presented work is devoted to the study of the motion of vortex loops after reconnection in superfluid helium. The helium temperature as well as the initial arrangement of the vortex loops varied. The data on the change in the length, average radius of curvature and velocity of vortex loops from the moment of reconnection to the moment of their collapse were obtained. A comparative analysis of the motion of a single vortex ring and a deformed vortex loop was carried out. All calculations were performed within the framework of the vortex filament method using the full Biot-Savard equation.