Perpendicular Angle Research Articles

Evaluation of Modular Roll-Setup to Roll Grooves into Steel Sheets

Hybrid structures made of aluminium and steel are used in an increasing amount to produce lightweight optimised parts, e.g. for the automotive industry. One option to produce these optimised components is a combination of a steel sheet with a reinforcing aluminium rib structure by high pressure die casting. Achieving a reliable junction between the different materials during the short casting time is a major challenge in creating these hybrid components. Improving this junction is the topic of an ongoing research study in which a form closure connection is enabled by structuring the steel surface prior to the casting process. In order to meet the demands of the later application, the surface structure has to ensure the filling during the casting as well as a stable form closure connection. Thus, deep groove structures with a perpendicular wall angel straight to the casting direction were identified, since a deeper structure increases the clamping area and a perpendicular wall angle improves the form closure connection. However, the production of this structure in a large scale and a short time becomes difficult using conventional structuring processes. In this work the capability of an adapted rolling process which consists of stacked discs with varying thickness and diameter was studied in order to manufacture these grooves. Several experiments were performed to determine the influence of the height reduction and rolling force on the resulting structure. First results obtained with the presented experiments show the good predictability of the resulting size of the structure depending on the thickness reduction and the rolling force normalised to one millimetre structured width.

Experimental measurements of a prototype high-concentration Fresnel lens and sun-tracking method for photovoltaic panel’s efficiency enhancement

Concentrator photovoltaic modules are a promising technology for highly efficient solar energy conversion. This system presents several advantages due to additional degrees of freedom that has been provided by the spectral separation such as cost and mass reduction, increase in the incident solar flux on PV cells and performances. This paper has proposed a unique photovoltaic solar cell system that consists of semi-Fresnel lens convergent structure and a novel two axis sun tracking module to enhance the efficiency of solar cell by using less cell area and energy losses. The grooves of this lens are calculated according to the refraction and convergent angles of the light easy for perpendicular incidence angle. The update time interval during tracking causes misalignment of the lens’ optical axis versus the sunrays. Then an inventive sun-tracking method is introduced to adjust the module so that the incident rays are always perpendicular to the module’s surface. As a result, all rays will be refracted with the predetermined angles. This way the focus area is reduced and smaller cells can be used. We also mentioned different module connections in order to provide compensation method during losses, for networks and power systems. Experimental results show that using semi-Fresnel lens, along with the sun-tracking method increases the efficiency of PV panel.

Ergonomic design and evaluation of the handle for an endoscopic dissector

The purpose of this study was to design an endoscopic dissector handle and objectively assess its usability. The handles were designed with increased contact area between the fingers and thumb and the eye rings, and the eye rings were modified to have a more perpendicular insertion angle to the finger midline. Four different handle models were compared, including a conventional product. Subjects performed dissection, exclusion, grasping, precision manipulation and precision handling tasks. Electromyography and subjective evaluations were measured. Compared to conventional handles, the designated handle reduced the muscle load in the extensor and flexor muscles of the forearm and increased subjective stability. The activity of the first dorsal interosseous muscle was sometimes influenced by the shape of the other parts. The ergonomically designed endoscopic dissector handle used in this study achieved high usability. Medical instrument designs based on ergonomic concepts should be assessed with objective indices.Practitioner Summary: The endoscopic dissector handles were designed with increased contact area and more suitable insertion angle between the fingers and thumb and the eye rings. Compared to conventional handles, the designated handle reduced the muscle load in the extensor and flexor muscles of the forearm and increased subjective stability.

An investigation on the defect structures and spin Hamiltonian parameters for the two orthorhombic Ti3+ centers in ZnWO4

By employing the perturbation formulae of the spin Hamiltonian parameters (SHPs) (g factors gxx, gyy, gzz, hyperfine structure constants Axx, Ayy, Azz and superhyperfine parameters Axx׳, Ayy׳, Azz׳) for a 3d1 ion in orthorhombically elongated octahedra and tetrahedra, the defect structures and the experimental EPR spectra are theoretically and systematically investigated for the two orthorhombic Ti3+ centers C1 and C2 in ZnWO4. Center C1 is ascribed to the impurity Ti3+ at host W6+ site associated with two nearest neighbor oxygen vacancies due to charge compensation. The resultant tetrahedral [TiO4]5– cluster is determined to undergo the local orthorhombic elongation distortion, characterized by the axial distortion angle Δθ (=θ–θ0≈–6.84°) of the local impurity-ligand bond angle θ related to θ0 (≈54.74°) and the perpendicular distortion angle Δε (=ε–ε0≈2.5°) related to ε0 (≈45°) of an ideal tetrahedron because of the Jahn–Teller effect. Center C2 is attributed to Ti3+ on Zn2+ site, and this octahedral [TiO6]9– cluster may experience the local axial elongation ΔZ (≈0.001Ǻ) and the planar bond angle variation Δφ (≈9.1°) due to the Jahn–Teller effect, resulting in a more regular oxygen octahedron. All the calculated SHPs (i.e., g factors for both centers, the hyperfine structure constants for center C2 and superhyperfine parameters of next nearest neighbor ligand W for center C1) show good agreement with the observed values. However, the theoretical results based on the previous assignment of center C1 as Ti3+ on W6+ site with only one nearest planar oxygen vacancy (i.e., five-fold coordinated octahedral [TiO5]7– cluster) show much worse agreement with the experimental data. The defect structures and the SHPs (especially the g anisotropies) are discussed for both centers. The present studies on the superhyperfine parameters of ligand W6+ for center C1 would be helpful to further investigations on the superhyperfine interactions of cation ligands which were rather scarcely treated before.

Water adsorption in metal–organic frameworks with open‐metal sites

H2O adsorptions inside porous materials, including silica zeolites, zeolite imidazolate frameworks, and metal–organic frameworks (MOFs) using molecular simulations with different water models are investigated. Due to the existence of coordinately unsaturated metal sites, the predicted adsorption properties in M‐MOF‐74 (M = Mg, Ni, Co, Zn) and Cu‐BTC are found to be greatly sensitive to the adopted H2O models. Surprisingly, the analysis of the orientations of H2O minimum energy configuration in these materials show that three‐site H2O models predict an unusual perpendicular angle of H2O plane with respect to the Metal‐O4 plane, whereas those models with more than three sites give a more parallel angle that is in better agreement with the one obtained from density functional theory (DFT) calculations. In addition, the use of these commonly used models estimates the binding energies with the values lower than the ones computed by DFT ranging from 15 to 40%. To correct adsorption energies, simple approach to adjust metal‐O(H2O) sigma parameters to reproduce the DFT‐calculated binding energies is used. With the refined parameters, the computed water isotherms inside Mg‐MOF‐74 and Cu‐BTC are in reasonable agreement with experimental data, and provide significant improvement compared to the predictions made by the original models. Further, a detailed inspection on the water configurations at higher‐pressure region was also made, and observed that there is an interesting two‐layer water network formed using three‐ and four‐site models. © 2014 American Institute of Chemical Engineers AIChE J, 61: 677–687, 2015

Detecting energy dependent neutron capture distributions in a liquid scintillator

A novel technique is being developed to estimate the effective dose of a neutron field based on the distribution of neutron captures in a scintillator. Using Monte Carlo techniques, a number of monoenergetic neutron source energies and locations were modelled and their neutron capture response was recorded. Using back propagation Artificial Neural Networks (ANN) the energy and incident direction of the neutron field was predicted from the distribution of neutron captures within a 6Li-loaded liquid scintillator. Using this proposed technique, the effective dose of 252Cf, 241AmBe and 241AmLi neutron fields was estimated to within 30% for four perpendicular angles in the horizontal plane. Initial theoretical investigations show that this technique holds some promise for real-time estimation of the effective dose of a neutron field.

Frequent excitations of T waves by earthquakes in the South Mariana Arc

We used broadband stations in Taiwan and on the Ryukyu Arc islands to investigate T waves induced by earthquakes in the Izu-Bonin-Mariana subduction zone. Of the 48 earthquakes that took place in 2005, 17 earthquakes exhibited T-wave signals consistent with predicted arrival times at stations. Of theses T-excited events, 13 were located in the South Mariana Arc, where the isobaths exhibit strong concave curvature, and were predominantly of normal faulting type. The energies of observed T waves were used quantitatively to evaluate the relative efficiency of receiver-side acoustic–elastic conversions by Gamma calculations. Results show that the steep slopes of offshore bathymetry together with nearly perpendicular angles of back azimuth relative to local isobaths are suitable conditions for T waves observations. In 2010, two clusters of repeated moderate earthquakes in the north and south ends of the Mariana Arc displayed stark contrasts in terms of T-wave excitations despite their normal faulting type. Examining of this discrepancy indicate that a specific curvature together with a specific radiation pattern accounts for the frequent excitations of T waves from shallow earthquakes in the South Mariana Arc.

Seed-to-seed-to-seed growth and development of Arabidopsis in microgravity.

Arabidopsis thaliana was grown from seed to seed wholly in microgravity on the International Space Station. Arabidopsis plants were germinated, grown, and maintained inside a growth chamber prior to returning to Earth. Some of these seeds were used in a subsequent experiment to successfully produce a second (back-to-back) generation of microgravity-grown Arabidopsis. In general, plant growth and development in microgravity proceeded similarly to those of the ground controls, which were grown in an identical chamber. Morphologically, the most striking feature of space-grown Arabidopsis was that the secondary inflorescence branches and siliques formed nearly perpendicular angles to the inflorescence stems. The branches grew out perpendicularly to the main inflorescence stem, indicating that gravity was the key determinant of branch and silique angle and that light had either no role or a secondary role in Arabidopsis branch and silique orientation. Seed protein bodies were 55% smaller in space seed than in controls, but protein assays showed only a 9% reduction in seed protein content. Germination rates for space-produced seed were 92%, indicating that the seeds developed in microgravity were healthy and viable. Gravity is not necessary for seed-to-seed growth of plants, though it plays a direct role in plant form and may influence seed reserves.

A compendium of AGN inclinations with corresponding UV/optical continuum polarization measurements

The anisotropic nature of active galactic nuclei (AGN) is thought to be responsible for the observational differences between type-1 (pole-on) and type-2 (edge-on) nearby Seyfert-like galaxies. In this picture, the detection of emission and/or absorption features is directly correlated to the inclination of the system. The AGN structure can be further probed by using the geometry-sensitive technique of polarimetry, yet the pairing between observed polarization and Seyfert type remains poorly examined. Based on archival data, I report here the first compilation of 53 estimated AGN inclinations matched with ultraviolet/optical continuum polarization measurements. Corrections, based on the polarization of broad emission lines, are applied to the sample of Seyfert-2 AGN to remove dilution by starburst light and derive information about the scattered continuum alone. The resulting compendium agrees with past empirical results, i.e. type-1 AGN show low polarization degrees (P < 1%) predominantly associated with a polarization position angle parallel to the projected radio axis of the system, while type-2 objects show stronger polarization percentages (P > 7%) with perpendicular polarization angles. The transition between type-1 and type-2 inclination occurs between 45 and 60 degrees without noticeable impact on P. The compendium is further used as a test to investigate the relevance of four AGN models. While an AGN model with fragmented regions matches observations better than uniform models, a structure with a failed dusty wind along the equator and disc-born, ionized, polar outflows is by far closer to observations. However, although the models correctly reproduce the observed dichotomy between parallel and perpendicular polarization, as well as correct polarization percentages at type-2 inclinations, further work is needed to account for some highly polarized type-1 AGN

Micro-cavity lasers with directional emission and comparison of their characteristics

We demonstrate Limaçon-shaped micro-cavity lasers with directional emission. In experiments, this kind of micro-cavity laser was fabricated with a deformed factor of ε = 0.41, characterized and compared with a traditional F–P cavity ridge laser prepared with the same material at a wavelength of about 10 μm. From the experimental results, the micro-cavity laser showed highly directional emission (of about 9 mW output peak power) with a parallel directional divergence angle of 30° and a perpendicular divergence angle of 67° at full width at half maximum, which is similar to that of the ridge laser. The threshold current density of the micro-cavity laser was about 40% lower than that of the ridge laser, and the quality factor was estimated to be up to 1140.

Keys to minimizing the risk of spinal cord trauma during a lumbar approach to thoracic epidural

Thoracic epidurals provide effective analgesia for thoracic or upper abdominal procedures for both adult and pediatric patients; however, using a thoracic approach to place an epidural catheter is not without risk as it requires needle placement immediately posterior to the spinal cord. Consequently, some clinicians prefer to use a lumbar approach (caudal approach in pediatric cases), or if unsuccessful at a thoracic level, they may thread the epidural catheter cephalad from that point. This issue of the Journal features an interesting study by Gamble et al. in which the authors used a porcine model to address the safety of threading an epidural catheter via a lumbar approach. In their study, the authors show that styletted stimulating thoracic epidural catheters can be advanced in a predictable manner to target thoracic myotomes using a lumbar approach. However, damage to the spinal cord was observed in several animals. It is important to point out that, in humans, such perturbing findings are probably limited to high lumbar approaches (i.e., above L2-L3). This is partly because the human adult spinal cord, unlike the porcine model used in the Gamble et al. study, typically ends at approximately the L1-L2 level. Thus, if needle entry occurs either at or below the L2-L3 level, the risk of direct blunt trauma caused by the initial threading of the catheter from the needle tip is minimized. Nevertheless, the results of Gamble et al.’s study clearly show the risks involved when a catheter is advanced directly towards the spinal cord, as in thoracic and high lumbar approaches. Several key factors influence the risk and potential for spinal cord damage during these approaches, including the angle of catheter insertion, catheter stiffness, and applied force. To address this issue, the relationship between these three factors must be considered. Force must be applied to advance the catheter to its desired target myotome level. This threading force is the total applied force needed to insert the catheter through the Tuohy needle into the epidural space. Threading force itself involves two component forces that must be considered during catheter insertion: a bending force, needed to advance the catheter out of the needle, and a parallel force, needed to thread the catheter cranially past any obstacle within the epidural space (Fig. 1). Assuming there is minimal obstruction along the spinal cord, the initial total threading force is then directly related to the bending force. This is shown in Gamble et al.’s experiment where, in most animals, difficulty was experienced in advancing the catheter beyond the needle tip. The perpendicular angle of insertion used by the authors suggests the need for considerable bending force to advance the catheter out of the needle. Furthermore, the authors speculate that catheter stiffness and the presence of the stylet added to the difficulties in initial catheter advancement. Thus, the bending force required to advance the catheter out of the needle is influenced by two key factors: angulation of the needle and catheter stiffness (i.e., styletted or not). To show this relationship, we used a simple in vitro setup to demonstrate the peak (kilogram) force generated when threading a styletted catheter at various needle angles (Figure). As shown, the peak force increases dramatically as the angulation of the needle approaches 0 (i.e., perpendicular) relative to the surface of the force gauge transducer. With an insertion perpendicular to the plane of the back (i.e., no angulation), these results suggest that the B. C. H. Tsui, MD (&) Department of Anesthesiology and Pain Medicine, University of Alberta, 8-120 Clinical Sciences Building, Edmonton, AB T6G 2G3, Canada e-mail: btsui@ualberta.ca

Clot in Bovine Arch Diagnosed by Transesophageal Echocardiography

Clot in Bovine Arch Diagnosed by Transesophageal Echocardiography

Pedicle screw nut loosening: potentially avoidable causes of spine instrumentation failure.

Dear Sir, Since the first successful fusion procedures in 1911 for the Pott disease, spinal surgical fixation devices have enhanced tremendous advancements in spinal surgeries with strong evidences showing that instrumented fusion produced a higher rate of fusion [1,2,3]. Although the pedicle screws are routinely used for spinal fixation, these devices can be associated with complications within a group of patients, the resulted failures may not actually be device-made failures but instead surgeon-related errors [4]. A 65-year-old man was operated for traumatic D12 fractures 6 months ago. After the surgery, everything seemed to be alright until the last month when he noticed pain in the operated region which increased with strenuous activities. There was no history of bowel and bladder disturbances recorded. General and systemic examinations were unremarkable. Motor and sensory examinations were normal. His wounds healed well and he was healthy. An X-ray check indicated the loosening of the lower left screw head (Fig. 1). Thus, the patient was being scheduled for the repositioning of the screws. The wound was re-examined and the loose nut was identified and repositioned (Fig. 2). The patient is now being followed-up and doing well. Fig. 1 X-ray dorso-lumbar spine showing asymmetry of the rods and dislodgement of the nut from screw head. Fig. 2 (A) Intraoperative images showing loosened nut lying outside the screw head. (B) Rod in the screw head after retrieval of screw. (C) Rods being pushed down into the screw head and (D) a new nut is placed into the screw head to secure the rod in place. ... Transpedicular instrumentation provides the most biomechanically rigid restraint to spinal motions in flexion, extension and torsion through segmental spinal purchase [5]. Apart from this, the pedicle screw systems require fewer instrumented segments thus are advantageous in preserving motion segments [6]. Despite these advantages, transpedicular fixations can be associated with the risks of screw loosening, screw breakage, screw/rod disconnection, pseudo-arthrosis, and nerve root injury which occurs in dural laceration and pedicle fracture during screw insertions [4,6]. Ahmed et al. [4] reported construct failures in the form of screw binding (6 cases), screw breakage (12 cases), screw/rod dislodgement (3 cases), progressive kyphosis (5 cases), disengaged screw's cup (2 cases), and broken rods (2 cases). To avoid such mechanical construct failure, it has been suggested that there should be proper applications of the rods over the screw head in a straight perpendicular angle and applications of the screw's cup in the correct mechanical manner. The use of variable-angle (poly-axial) screws can minimize the need for rod contouring thus avoiding the pre-stress load applied on the construct and reducing the early construct failure [4]. We could not identify the true occurrences and reasons for the loosening and disengagement of the screw heads. In order to avoid such a potentially preventable complication, the handling of implants is very important. When tightening the nut, withdraw from adjusting the nut, and, instead, rotate counterclockwise until the screw head loosens and produces a tuck sound. Thus, the nut is tightened with no gaps between the grooves in the screw head and the ridges.

A different perspective on conspicuity related motorcycle crashes

The most common type of conflict in which a motorcyclist is injured or killed is a collision between a motorcycle and a car, often in priority situations. Many studies on motorcycle safety focus on the question why car drivers fail to give priority and on the poor conspicuity of motorcycles. The concept of ‘looked-but-failed-to-see’ crashes is a recurring item. On the other hand, it is not entirely unexpected that motorcycles have many conflicts with cars; there simply are so many cars on the road. This paper tries to unravel whether – acknowledging the differences in exposure – car drivers indeed fail to yield for motorcycles more often than for other cars. For this purpose we compared the causes of crashes on intersections (e.g. failing to give priority, speeding, etc.) between different crash types (car–motorcycle or car–car). In addition, we compared the crash causes of dual drivers (i.e. car drivers who also have their motorcycle licence) with regular car drivers. Our crash analysis suggests that car drivers do not fail to give priority to motorcycles relatively more often than to another car when this car/motorcycle approaches from a perpendicular angle. There is only one priority situation where motorcycles seem to be at a disadvantage compared to cars. This is when a car makes a left turn, and fails to give priority to an oncoming motorcycle. This specific crash scenario occurs more often when the oncoming vehicle is a motorcycle than when it is a car. We did not find a significant difference between dual drivers and regular car drivers in how often they give priority to motorcycles compared to cars.

Correlation of foot-strike pattern and performance in a mid-size city marathon

Introduction: A small number of studies have provided “inrace” foot-strike prevalence of runners in midto long-distance races. The recent studies each classified the foot-strike of less than 300 runners in half-marathon and marathon races. The runner populations varied from all elite runners to mostly “recreational” runners. The prevalence of heel-strike ranged from 74.9% to 93.0%. Correlation with performance, however, has been impossible due to the small sample sizes. Using a seven-fold larger runner population, this study aims to more accurately define the prevalence of heel-strike in a mid-size city marathon and to determine if a correlation between foot-strike and performance exists. Patients/materials and methods: 2112 runners in the 2011 Milwaukee Lakefront Marathon were filmed at the 5.02-mile mark using a Casio EX-ZR100,with a frame rate of 240 frames/s. The camerawassecurelymountedataheightof24 in. andadistanceof12 in. from the side of the road. The camerawas angled at 30degrees from a direct lateral, or perpendicular angle. Foot-strike classification was determined by a 3-member panel utilizing frame-by-frame analysis. Classifications included fore-foot strike, mid-foot strike, heel strike, and split strike (asymmetric between consecutive footstrikes). Results: 1991 runners were classified by foot-strike pattern: 11 fore-foot (0.55%), 101 mid-foot (5.07%), 1865 heel (93.67%), and 14 split (0.70%). The heel-strike prevalence of 93.67%wasmore prominent than in prior studies of both recreational and elite runners. A correlation was demonstrated between foot-strike and performance (as measured by position in race at the 5.02-mile mark), with a p-value <0.0001. Fore-foot strikers were followed by splitstrikers, then mid-foot strikers, then heel-strikers. There was no significant correlation demonstrated between foot-strike and gender (p-value =0.0727). Discussion and conclusions: This study is the largest “in-race” observational study of marathon runners to date. It unequivocally demonstrates: (a) heel-strike prevalence in a predominantly subelite population of runners is significantly greater than previously documented in more elite running populations and (b) foot-strike is correlated with performance (as measured by position in race). Shoe wear (minimalist versus traditional) was not correlated with position in race in non-heel strikers, perhaps placingmore emphasis on foot-strike than shoewear for performance. Further research is necessary to elucidate whether non-heel strike running form produces a faster runner or a faster runner produces a non-heel strike running form.

Limaçon-shaped micro-cavity lasers with directional emission and its performance

We fabricated a limaçon-shaped semiconductor micro-cavity laser by using quantum cascade laser material. The device performance was investigated and compared to a traditional F–P cavity ridge laser prepared with the same material. From the experimental results, the threshold current density of the micro-cavity laser was about 36% lower than that of the F–P cavity ridge laser, and the quality factor was improved up to 1130 by combining dry etching to achieve smooth vertical sidewalls with wet etching. From the mode spacing, we confirmed the emission of whispering gallery type resonance mode at about 10 μm wavelength. From the far-field pattern results, we achieved a highly directional emission with parallel directional divergence angle of 32° and perpendicular divergence angle of 66° at full width of half maximum for the micro-cavity laser with a deformed factor of 0.42, which is similar to that of the F–P cavity ridge laser. Finally the reliability testing of the micro-cavity lasers was carried out.

Vertical coherence and forward scattering from the sea surface and the relation to the directional wave spectrum

Results of an experiment to measure vertical spatial coherence from acoustic paths interacting once with the sea surface but at perpendicular azimuth angles are presented. The measurements were part of the Shallow Water 2006 program that took place off the coast of New Jersey in August 2006. An acoustic source, frequency range 6-20 kHz, was deployed at depth 40 m, and signals were recorded on a 1.4 m long vertical line array centered at depth 25 m and positioned at range 200 m. The vertical array consisted of four omni-directional hydrophones and vertical coherences were computed between pairs of these hydrophones. Measurements were made over four source-receiver bearing angles separated by 90°, during which sea surface conditions remained stable and characterized by a root-mean-square wave height of 0.17 m and a mixture of swell and wind waves. Vertical coherences show a statistically significant difference depending on source-receiver bearing when the acoustic frequency is less than about 12 kHz, with results tending to fade at higher frequencies. This paper presents field observations and comparisons of these observations with two modeling approaches, one based on bistatic forward scattering and the other on a rough surface parabolic wave equation utilizing synthetic sea surfaces.

Computed Tomography Analysis of the Femoral Tunnel Position and Aperture Shape of Transportal and Outside-In ACL Reconstruction

Background: The desire to perform independent femoral drilling in anterior cruciate ligament (ACL) reconstruction has prompted interest in both the transportal (TP) and outside-in (OI) techniques. However, there have been no in vivo studies on the differences in femoral aperture shape between the 2 techniques. Purpose: To evaluate the femoral tunnel aperture shape and femoral tunnel position between ACL reconstruction using the TP and OI techniques. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 80 patients were randomized to undergo double-bundle ACL reconstruction using either the TP (n = 40) or OI (n = 40) technique. The femoral tunnel aperture shape (height/width ratio), aperture axis angle (angle between the aperture axis and femoral shaft axis), and femoral tunnel position were assessed by computed tomography. Results: The mean height/width ratio of the anteromedial (AM) femoral tunnels in the TP group (1.35 ± 0.16) was significantly more ellipsoidal than that in the OI group (1.22 ± 0.16) (P = .008). There was no difference between the 2 groups in the posterolateral (PL) tunnels (TP, 1.32 ± 0.23; OI, 1.35 ± 0.29; P = .99). The mean aperture axis angle of the PL femoral tunnels in the OI group was significantly more perpendicular to the femoral shaft axis and had a more variable range than that in the TP group (P = .007). The mean PL femoral tunnel position in the OI group was significantly shallower and a little higher than that in the TP group (P = .006). Conclusion: The TP technique revealed a more ellipsoidal AM femoral tunnel aperture than the OI technique. The mean PL femoral tunnel position in the OI group was significantly shallower than that in the TP group, with a more variable and more perpendicular aperture axis angle to the femoral shaft axis. Clinical Relevance: The TP technique might be more advantageous than the OI technique in terms of graft coverage, with a more ellipsoidal AM femoral tunnel and more horizontal and consistent PL aperture axis angle. In addition, it may be useful to consider the shallower PL femoral tunnel positions created with the OI technique.

EFFECT OF ANISOTROPY AND SPATIAL COMPOUND IMAGING ON RENAL CORTICAL ECHOGENICITY IN DOGS

The echogenicity of the renal cortex is an important parameter to consider in dogs that are suspected to have renal dysfunction. Focal increases in echogenicity have been attributed to neoplasia, infection, calcification, fibrosis, gas, and infarction. Anisotropic backscatter has been described as a source of focally increased renal cortical echogenicity in several species. The source of anisotropy appears to be the medullary rays, which are oriented perpendicular to the renal capsule. Spatial compound imaging (SCI) is an ultrasound setting that uses beam steering to acquire and average several overlapping scans of an object from different view angles, creating a compound image that is updated in real time. The impact of insonation angle and SCI on renal cortical echogenicity was evaluated ex vivo in eight kidneys from four dogs. Significant angle-dependent differences in cortical echogenicity were detected with both microconvex and linear transducers (P < 0.0001). Furthermore, the angle-dependent echogenicity differences persisted when SCI mode was used. Our finding that echogenicity was increased using a perpendicular insonation angle (90°) relative to the tubules, compared to a parallel insonation angle (0°) should assist in the interpretation of ultrasonographic images of the dog kidney.

Impact-abrasion wear of wear-resistant steels at perpendicular and tilted angles

Earth moving and processing machinery has to withstand heavy wear caused by impacts and scratching by the soil. Especially, the edges are subjected to heavy wear. To simulate these conditions, impeller–tumbler impact-abrasion wear testing equipment was used to determine the wear resistance of four steel grades at perpendicular and tilted sample angles. The angles were selected to simulate the loading conditions. Natural granite rock was used as abrasive. The amount of wear was clearly smaller in the harder materials. The significance of hardness was quite similar at both sample angles in the steady-state wear of wear-resistant steels. On the initial state wear, hardness had a slightly greater effect at the perpendicular angle due to more severe wear in sample edges already at the beginning of the test. Overall, the largest differences in wear were observed in the sample edges. At the perpendicular sample angle, the sample edges were much more rounded. Some small differences were observed in the surface formations due to dissimilar movement of the abrasive. Deformed surfaces and fractured lips indicated that wear occurred mainly by the deformation of material followed by the removal of the deformed areas through impacts. In addition, scratches and dents were observed. It was found that larger sized abrasives caused higher mass loss than abrasives of similar mass but smaller size. Moreover, same amount of abrasive particles in each test reduces the scatter of the results.