Transverse Joints Research Articles

A novel method for identifying damage in transverse joints of arch dams from seismic responses based on the feature of local dynamic continuity interruption

Without the difficulty of applying particular excitations on arch dams, a method using the correlation coefficients of time-scale representations (CCTSRs) of seismic responses to identify the damage in transverse joints is proposed. The identification of damage using the CCTSR method is characterized by comparing the time-scale representations (TSRs) of paired seismic accelerations measured from two neighboring points crossing the transverse joints horizontally. With the CCTSR method, the TSRs of measured seismic accelerations are produced with the continuous wavelet transform; the comparison of the TSRs is carried out by calculating the correlation coefficients. The correlation coefficients of the paired TSRs are combined with the defined damage intervals to evaluate the positions and severities of the damage. The method’s feasibility is numerically verified via the identification of the damage in transverse joints by discussing the effects of the wavelet functions, seismic excitations, and noise resistance. The method’s effectiveness is experimentally validated via the detection of the damage in transverse joints of a scaled arch dam model subjected to artificial seismic loads. The proposed CCTSR method can localize the positions of various damage scenarios and quantify the damage severities caused by progressive seismic loads.

Nonuniform load distribution of two-dimensional C/SiC z-pinned joints with four pins in a rectangular array prepared via chemical vapor infiltration

The design of ceramic matrix composite (CMC) mechanical joints takes into account the pseudoplastic mechanical behavior of CMC fasteners and the effect of the nonuniform microstructure. In this study, based on the linear correlation between the shear performance of two-dimensional (2D) C/SiC rivets and the rivet porosity, special z-pinned joints with four pins in a rectangular array with different porosities were prepared via the chemical vapor infiltration online gas-phase joining method, and a method is proposed to indirectly characterize the pin load distribution by measuring the strain distribution around the holes. The results show that the nonuniform distribution of the 2D C/SiC rivet density leads to an uneven distribution of the pin loads in the z-pinned joints with four pins in a rectangular array. The bearing ratio of the transversal rivets depends on the inverse of the ratio of the compliance coefficient of the two. The longitudinal rivets are capable to transfer the load; that is, the bottom transversal joint of the rivets is loaded first, and after the load limit is reached, the top transversal joint of the rivets starts to be loaded. Matrix cracking, crack deflection, interlayer sliding, fiber shearing, and fiber pull-out control rivet shearing. The dense rivets squeeze around the holes, leading to an uneven distribution of the pin loads. Oxidation at 700 °C leads to the fibers debonding from the matrix and cracking, which promotes crack deflection, interlayer sliding, and fiber pull-out; thus, the uneven pin load distribution tends to be uniform.

Blast Performance and Damage Evaluation of High Arch Dams Subjected to Far-Field Underwater Explosions: Consideration of Joints

The blast performance of 300-m-high arch dams is an important subject which has been studied widely over the years. An arch dam is convex on the upstream face, and the load is transmitted along the arch axis to the abutments at the ends of the dam. However, the integrity of arch dams is affected by the transverse contraction joints. The blast resistance performance of a 300-m-high arch dam subjected to far-field underwater explosion was investigated considering contraction joints. The acoustic–structural method was employed to model the underwater explosion loads and the interactions among the dam–reservoir–foundation system. To verify the reliability of the acoustic–structural method, a 1∶200-scale model of an arch dam subjected to far-field underwater explosion was tested. A zero-thickness cohesive element was employed to model the mechanical behavior of contraction joints with grouting. Nonlinear dynamic response and damage progress of the high arch dam with transverse contraction joints to the far-field underwater explosion were investigated in terms of peak displacement, velocity, and damage modes. The tensile damage mechanism of the arch dam subjected to the far-field underwater explosion was discussed. The damage modes and deformation mechanism of high arch dams at the different positions of initiation point were presented. A damage index based on the damaged area in the downstream face and foundation face is proposed to evaluate the blast performance of high arch dams subjected to far-field underwater explosions. The results show that the contraction joints have a certain influence on the nonlinear dynamic and damage modes of high arch dams subjected to the far-field underwater explosion. The damage is larger with explosive charges near the one-quarter arch ring in the weak stiffness bank due to the asymmetry of the arch dam.

Association Between the Medial-Lateral Quadriceps and Hamstring Muscle Thickness and the Knee Kinematics and Kinetics During Single-Leg Landing.

Muscle thickness can influence the joint kinematics and/or kinetics during dynamic activities. The relationship between the muscle thickness of individual quadriceps and hamstrings or medial-to-lateral thigh muscle thickness ratio and the knee kinematics/kinetics with respect to anterior cruciate ligament (ACL) injury risk remains unclear. Higher medial-to-lateral thigh muscle thickness ratio would be associated with lower knee valgus angle/moment and lower tibial internal rotation angle/moment during single-leg landing. Cross-sectional. Level 4. Muscle thickness of the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and semitendinosus (ST) of 30 healthy participants (16 males and 14 females) were measured using ultrasound. Knee joint kinematics and kinetics during single-leg landing were obtained. Stepwise multiple regression analysis, a follow-up Fisher's r to z test to examine the sex as a moderator, and independent t tests to evaluate sex difference were performed. Both knee valgus moment (R2 = 0.466, P < 0.001) and tibial external rotation moment (R2 = 0.330, P < 0.001) at peak anterior tibial shear force during single-leg landing were negatively correlated with medial-to-lateral (ie, (VM+ST):(VL+BF)) thickness ratio regardless of sex, whereas medial-to-lateral thigh muscle thickness ratio was not correlated with knee valgus and tibial external rotation angles. Male participants exhibited higher (VM+ST):(VL+BF) thickness ratio than female participants (P = 0.005), and lower knee valgus moment (P = 0.04) and tibial external rotation moment (P = 0.05), as well. The knee joint moments in frontal and transverse planes during single-leg landing were associated with the medial-to-lateral thigh muscle thickness ratio; thus, the medial-lateral thigh muscle thickness could be a potential contributor to frontal and transverse plane knee joint loading during dynamic movement. Strength training that aims to selectively strengthen the medial/lateral thigh muscles might be considered in a new ACL injury prevention training program to alter the biomechanical parameters associated with ACL injuries.

Fatigue strength of shot-peened as-welded joints and post-weld-treated and subsequently clean-blasted fillet weld joints

Surface treatment methods, such as shot peening and clean blasting, can improve the fatigue strength of welded joints. The aim of the current work is to experimentally evaluate the effects of clean blasting on the fatigue performance of post-weld-treated joints made of normal, high-strength, and ultra-high-strength steels, as well as obtain the fatigue strength improvement gained by the shot peening processes in welded connections made of different steel grades using literature data. A literature review was carried out to extract fatigue test data of welded joints, considering both clean blasting and shot peening processes. This data was statistically re-evaluated and used for a comparison to the results obtained in the current experimental work which focuses on evaluating the improvement gained by the clean blasting after post-weld treatments. Experimental fatigue tests were carried out on non-load-carrying transverse attachment joints prepared with gas metal arc welding, and made of S355, S700, and S1100 structural steels. TIG dressing and HFMI treatment post-weld treatments were implemented and, subsequently, the specimens were blast-cleaned using two different abrasives: corundum and sand. The re-analysis of existing fatigue test data indicated higher improvement by shot peening, i.e., average improvements of 1.71 and 1.52 in the fatigue strength for butt weld and fillet weld joints, respectively, than by clean blasting process for which an average improvement of 1.19 in fatigue strength was obtained. The enhancement factors, however, highly varied among different data sets indicating a clear impact of processing parameters on the improvement level. The statistical re-analyses considering all data sets of shot-peened specimens (butt weld and fillet weld joints) showed that one fatigue (FAT) class higher fatigue strength could be recommended for shot-peened joints compared to the as-welded condition with weld toe failures. The experimental work on the post-weld-treated joints indicated that the fatigue strength of clean-blasted joints was similar to that of non-blasted joints, and thus showing no major advantages or disadvantages by the clean blasting post-weld-treated joints with corundum and sand.

Coal permeability behaviors and non-uniform deformations under various boundary conditions: Part 1 – Experimental observations

Permeability is a key parameter to evaluate the ability of coal reservoir for transmitting coalbed methane (CBM). Deformations of internal components of coal caused by the variations of physical fields control the evolution of coal permeability. And there is obvious non-uniform in the deformations of coal bulk and fracture due to the heterogeneity of coal. However, at present, the evolution of non-uniform deformation and its relationship with coal permeability are unclear. In this study, first of a two-part series, we completed a series of experiments to measure the permeability, axial strain, radial strain, overall strain and fracture strain of a coal sample under different boundary conditions (constant confining pressure, constant effective stress and uniaxial strain) at different injection pressures of carbon dioxide (0.2 MPa, 1.0 MPa, 2.0 MPa, 3.0 MPa, 4.0 MPa and 5.0 MPa). And we defined the comprehensive non-uniform deformation index (CNDI) as the ratio of the fracture strain to the overall strain to quantify the degree of the non-uniform deformation between coal bulk and fracture. The experimental results show that the deformation of the coal sample in the longitudinal joint direction is smaller than that in the transverse joint direction, which indicates that the mechanical properties of the coal sample is anisotropic in different directions. And there are obvious differences between the deformations of coal bulk and fractures. When the gas pressure is in the range of 0.2 ∼ 5.0 MPa, the non-uniform deformations are vaguely related to the change of gas pressure, but closely related to the type of boundary conditions. The influence of gas pressure under displacement-controlled boundary condition (uniaxial strain) on the CNDI is greater than that under stress-controlled boundary conditions (constant confining pressure, constant effective stress). In addition, we also observed the phenomenon by the experimental results of the constant effective stress group: the permeability decreases gradually with the gas pressure even after removing the influence of gas slip effect, which is inconsistent with the traditional theoretical solution under the constant effective stress condition. Based on the fact that coal sample is a heterogeneous body, we tentatively believe that one of the reasons for this inconsistency may be that the traditional definition of effective stress does not include the effect of gas adsorption.

Comparison of Canine Forelimb Kinematic Joint Angles Collected with 2D and 3D Models.

The aim of this study was to compare a Joint Coordinate System (JCS) three-dimensional (3D) kinematic model of the canine forelimb with more widely used linear (LIN) and segmental (SEG) 2D models. It was an in vivo biomechanical study. Normal adult mixed breed dogs were used in this study (n = 6). Nineteen retroreflective markers were applied to the skin of dogs' right forelimbs. Dogs were trotted and walked through the calibrated testing space. The first five good trials were used to generate sagittal plane (flexion and extension angle) waveforms from 3 different models (JCS, LIN and SEG) for the shoulder, elbow and carpal joints. The JCS model also generated transverse and frontal plane joint angular data (internal/external and abduction/adduction angles) for all three joints. Minimum, maximum and total angular displacement was calculated for each joint. Comparison of sagittal plane waveforms was performed before and after waveform alignment using statistical parametric mapping. Each model produced similar sagittal plane waveforms, though the LIN model had a greater vertical shift along the y-axis for the shoulder and elbow. Before waveform alignment, differences were revealed between the LIN model when compared to JCS or SEG model at a trot. No differences were revealed at a walk. After waveform alignment, no differences were revealed between models at a walk or trot. There were no differences in angular displacement measurements between models before or after waveform alignment at a walk or trot. The 3D JCS model reported in this study produced sagittal plane waveforms comparable to conventional 2D models while also providing joint specific information from other planes of motion.

Evaluation of Bonding Interior Layer Failure Strength Modes in the Composite Pavement

A tack coat is a minimal coating of asphalt cement, cut-back asphalt, or asphalt emulsion to an existing pavement surface between layers to guarantee proper bonding between the two layers and longitudinal and transverse Joints. Numerous researchers have assessed interlayer adhesion employing failure-mode behavior tests, such as pull-off, direct shear, and torsion testing. This study aims to quantify the best tensile resistance obtained using PG (76-10) modified asphalt cement with polymer 4.5%, Sikadur®-31 CF (S.E) usage at elevated temperatures between +25 °C and +45 °C, an epoxy-resin-based adhesive, and repair mortar with specific fillers. And Nitomortar TC2000 epoxy (F.E) resin-based sealing compound from Fosrok Company. All are applied on concrete surfaces at a rate of 0.5 kg/m2 except for Nitomortar, which depends on layer thickness ranges between (1-2.5) mm instead of the application rate. The Proceq DYNA Z16 pull–off tester is used to measure the tensile strength at a rate of 2lb/s. It is found that the average tensile strength of the tack coat materials is (0.607, 1.481, 2.622) MPa, respectively. It concluded that (F.E) epoxy has the maximum tensile strength. Also, adding polymer to asphalt increased adhesiveness. Failure strength modes of interior bonding varied between cohesive failure adhesive, adhesive failure, and cohesive failure in the concrete substrate.

Conducting experimental studies of cement concrete pavement joints

To increase the life of roads in our Republic, several reforms are being carried out to operate roads with high strength and efficiently use available materials. Experience in constructing cement concrete roads shows that, over time, elevations of several millimeters can form between the slabs. The formation of disturbances hurts the longitudinal plane of the carriageway. It increases the driving resistance, makes the movement of vehicles uncomfortable, and causes the vehicles to oscillate. This increases the load on the roadway. Therefore, the study and development of recommendations for forming a shift between cement concrete paving slabs are relevant today. A study of negative changes (formation of steps) of the cement concrete pavement from dry-hot climatic conditions and over time in longitudinal, transverse compression, transverse expansion, floating, false, and working seams is presented. The results were obtained on 315320 km of highway A 380 “Guzor-Bukhara-Nukus-Beyneu” by measuring the heights and subsidence of the plates of transverse expansion joints with an electronic caliper and protractor. Using a mobile laboratory machine, “Ford Terrassa”, the longitudinal smoothness of the coating of this object was determined, and the results were obtained. Then a correlation plot of the effect of variation between plates (steps) on the smoothness of the coating (IRI) was plotted.

СМЕСЕВЫЕ ПОЛИМЕРНЫЕ КОМПОЗИЦИИ КАК ОСНОВА АДГЕЗИОННОГО СЛОЯ ДЛЯ БИТУМНЫХ ЛЕНТ

The stability of the surface layers of asphalt concrete (especially at longitudinal and transverse joints of strips laid at different times) can be increased by using bitumen-polymer joining tapes. However, in a number of cases, reliable fastening of the docking tape in an upright position cannot be achieved due to unsatisfactory natural and climatic conditions, creating foci of subsequent destruction. One widely discussed solution is to create an adhesive layer on the side of the connecting bitumen-polymer tape capable of providing the necessary level of adhesion from the moment it is distributed until the end of laying and compaction of a fresh layer of hot asphalt concrete. This study is devoted to the study of two-component compositions based on high-pressure polyethylene and styrene-butadiene thermoplastic. The dispersion medium for this study was residual bitumen from petroleum fractions of Yareg oil, which differs in composition from traditional viscous petroleum bitumen mass produced through oxidation.

Evaluation of Diagnostic Performance of Bd Max Ebp Assay in Patients with Diarrheal Illness

Objective: Detection of the etiological agents in patients with acute diarrhea is challenging due to a wide variety of pathogens. The aim of this study is to evaluate the diagnostic performance of BD Max Enteric Bacterial Pathogens (EBP) PCR assay in patients with diarrheal illness. Methods: Between 1 January 2014 and 31 May 2015, stool samples from pediatric or adult patients with diarrhea submitted for routine analysis of bacterial stool pathogens were included in the study. We compared the BD Max EBP PCR assay to culture for the detection of Salmonella spp., Shigella spp., Campylobacter jejuni, and Campylobacter coli and an EIA for Shiga toxins 1 and 2. Discordant results were adjudicated by either antigen detection methods or Film array GI Panel. Results: When coinfections were excluded, the positive percent agreement values for the BD Max EBP assay (PPA) was 100% and negative percent agreement (NPA) was between 98.0%-99.7%, when compared with culture and EIA. After discrepant analysis, the PPA values for the BD Max EBP assay was 100% and NPA was between 99.5%-100%. Conclusion: The BD Max EBP assay showed a high correlation rate with conventional and molecular methods for the detection of stool pathogens.

The Localizations of Osteoarthritis in the Knee, Ankle and Foot Joints of Cadaver: Comparison in Radiological, Morphological and Histopathological Aspects

Objective: Osteoarthritis (OA) is the most common joint disease. In this study it was aimed to compare the general features of OA such as location, placement, severity and shape of the lesions in terms of radiological and morphological aspects and to determine their relationship with each other. Methods: In our study, the antero-posterior and lateral radiographies of knee talocrural and transverse tarsal joints of 20 cadavers by age between 30 and 50 years were taken. The results obtained from the radiological examination were graded according to the Kellgren and Lawrence scale. For each of the identified regions, the presence of degenerative changes was noted. Then samples were taken from these regions were examined by microscopic methods. The cartilage degeneration changes, presence of fibrillations, density, depth, chondrocyte aggregation, and necrotic changes were evaluated. Results: In the radiological examination OA was found in 35% in knee joint, 25% in the talocrural joint, 15% in the transverse tarsal joint. In the morphological examination OA was found in 31.5% knee joint, 25% ankle joint and 5% transverse tarsal joint. In the microscopic examination OA was found in 94.7% knee joint, in 94.7% ankle joint and in 100% transverse tarsal joint. Conclusion: Although radiological and macroscopic OA was detected in approximately 1/3 of cadavers aged between 30 and 50 years, degeneration of varying degrees was detected in all joints examined in microscopic examination. This shows that an advanced age disease OA, starts at a very early age.

Application of a Joint Coordinate System Kinematic Model to the Canine Thoracic Limb.

The aim of this study was to apply a three-dimensional kinematic model to the canine thoracic limb using a joint coordinate system. Six clinically normal adult mixed-breed dogs. Dogs had 19 retroreflective markers affixed to the skin of the right forelimb. Twelve infrared cameras were arranged in a circle around the testing space, recording the locations of the markers as dogs walked and trotted through the testing space. Five trials were used of both walks and trots at velocities 0.9 to 1.2 m/s and 1.7 to 2.1 m/s respectively. Raw marker location data were used to generate a joint coordinate system, and a six degrees of freedom model of the canine forelimb was created. Three-dimensional kinematic angles were collected for the shoulder, elbow and carpal joints. Sagittal, transverse and frontal plane kinematics joint angles were generated by use of a joint coordinate system. Range of motion was calculated for each joint in all three planes. This minimally invasive joint coordinate system model can be used in both clinical and research settings to determine changes in range of motion of the shoulder, elbow or carpus in the canine forelimb in three dimensions.

Performance evaluation of continuous reinforced concrete pavement constructed in hilly region

Continuously reinforced concrete can be an excellent pavement solution for heavy traffic. The CRCP technique eliminates the transverse joints as it contains longitudinal reinforcement. This paper presents the details of CRCP road constructed by author, challenges faced due to steep gradient and heavy rainfall and the techniques adopted to resolve the issues. This CRCP road is being utilized for mixed type of traffic, including heavy traffic for last four years without any maintenance. The performance evaluation has been carried out recently by adopting Visual Condition Assessment Survey Technique. The measurements for various distress parameters such as longitudinal cracking, transverse cracking, punchouts, hairline cracks and joint deterioration, have been carried out. Also, the special observations noted during the Visual condition assessment survey have been discussed in detail. The performance evaluation shows that the CRCP is in ‘Low Severity Level’. The case study presented in detail and the performance evaluation carried out shows that CRCP is an effective technique for pavement construction.

Analysis of Temperature Sensitivity and Cracking Causes in Suspension Bridge Anchorage Based on Numerical Simulation

Mass concrete, a common structure in bridge engineering, is frequently threatened by cracking. Based on the gravity anchorage of a long-span suspension bridge that has been in operation for more than ten years, the causes of the cracks growing year by year in the anchorage were analyzed in this paper. The refined numerical model of the anchorage was established using the space finite-element software. Taking full account of the environmental characteristics of the bridge site, the temperature sensitivity of the anchorage was simulated and analyzed, as well as the stress distributions on the surface of each side of the anchorage at different temperatures. The calculation results showed that there is little correlation between anchorage cracking and anchorage bolt force. Under condition two, the temperature increased 20°C, the principal tensile stress of anchorage reached to 1.5 times of the allowable stress. Under condition six, the anchorage surface temperature at 40°C suddenly dropped to 20°C, and the principal tensile stress reached 2.4 times the allowable stress. Thus, under the dual effects of internal and external constraints, the cold hit effect of the mass concrete anchorage resulted in the sudden drop of the surface temperature of the anchorage concrete to produce “internal constraint cracks”, and the overall temperature rise caused the expansion of the anchorage concrete to produce “external constraint cracks.” The two types of cracks led to the vertical cracks of the anchorage. Additionally, the environmental and construction factors were the main causes of the cracking in transverse construction joints. Finally, the anchorage was reinforced with high-performance concrete with an anticrack reinforcement mesh, which presented good results in the follow-up observation, providing a certain reference value for similar projects.

Coverage maps demonstrate 3D Chopart joint subluxation in weightbearing CT of progressive collapsing foot deformity

A key element of the peritalar subluxation (PTS) seen in progressive collapsing foot deformity (PCFD) occurs through the transverse tarsal joint complex. However, the normal and pathological relations of these joints are not well understood. The objective of this study to compare Chopart articular coverages between PCFD patients and controls using weight-bearing computed tomography (WBCT). In this retrospective case control study, 20 patients with PCFD and 20 matched controls were evaluated. Distance and coverage mapping techniques were used to evaluate the talonavicular and calcaneocuboid interfaces. Principal axes were used to divide the talar head into 6 regions (medial/central/lateral and plantar/dorsal) and the calcaneocuboid interface into 4 regions. Repeated selections were performed to evaluate reliability of joint interface identification. Surface selections had high reliability with an ICC > 0.99. Talar head coverage decreases in plantarmedial and dorsalmedial (− 79%, p = 0.003 and − 77%, p = 0.00004) regions were seen with corresponding increases in plantarlateral and dorsolateral regions (30%, p = 0.0003 and 21%, p = 0.002) in PCFD. Calcaneocuboid coverage decreased in plantar and medial regions (− 12%, p = 0.006 and − 9%, p = 0.037) and increased in the lateral region (13%, p = 0.002). Significant subluxation occurs across the medial regions of the talar head and the plantar medial regions of the calcaneocuboid joint. Coverage and distance mapping provide a baseline for understanding Chopart joint changes in PCFD under full weightbearing conditions.

Assessing Premature Cracks in Urban Concrete Pavements

There are many urban jointed plain concrete pavements (JPCPs) constructed annually in the U.S. by counties, cities, and municipalities, which typically use state department of transportation standards but are not part of a systematic check to determine if design, construction, and performance are meeting expectations. A field evaluation survey with nondestructive testing was initiated on urban JPCPs throughout Illinois to assess performance and identify any deficiencies in design and construction. A total of 67 JPCPs were selected based on their design features and age. A significant number of sections (57%) were selected because they exhibited some level of premature cracking. Based on the field investigation, multiple mechanisms were proposed to explain the premature cracks. Many transverse and longitudinal cracks observed had excessive slab lengths or widths that were inconsistent with best slab geometry practices. There was no link established between observed cracking and the slab-base frictional restraint or the concrete mixture. For some sections, ultrasonic tests over the contraction joints determined certain joints had not activated and likely contributed to transverse cracks in adjacent slabs. Lack of dowel bar lubrication at the transverse contraction joints was also a plausible mechanism that restrained joint movements and produced excessive tensile stresses in the slab, which led to premature transverse cracks. The mechanisms leading to almost all observed premature cracks for these urban JPCPs were attributed to not adhering to existing state standards (slab geometry limits) and specifications (saw-cut timing/depth and dowel lubrication) during the pavement design and construction phases.

On the TSD deflection velocity measurements: a revision to the current state of the art and discussion over its applicability for concrete pavement assessment

ABSTRACT The fourth-generation TSD can provide pavement deflection data at a much higher rate than previous versions. This data is valuable to evaluate the structural health of the transverse joints in concrete pavements. Analysis of TSD measurements from a jointed pavement segment allowed the detection of a mistake in the way the TSD's deflection velocity [vy] data is processed to get deflection slope [S] estimates: We state and prove that the well-known direct relationship between vy and S is only valid in limited scenarios, and particularly invalid nearby the transverse joints. We highlight that vy is made up of two components, one of which is related to S and that at the vicinity of a discontinuity in the pavement structure, the second component of vy gains relevance and explains the discrepancy between vy and S. Also, it is shown that TSD vy measurements gathered near a joint resemble vy signals simulated with a linear elastic model. Thus, this study brings new insight into the contents of a TSD vy measurement and buttresses the TSD’s reliability as a vy measurement device. Plus, it suggests that further research should develop TSD data interpretation schemes based on vy instead of deflection slopes and depths.

Reliability and criterion validity of two-dimensional movement assessments in those with patellofemoral pain

ObjectivesDetermine criterion validity and intra/inter-rater reliability of 2-dimensional (2D) knee frontal plane projection angle (kFPPA), hip frontal plane projection angle (hFPPA), and dynamic valgus index (DVI) during forward step-downs in those with patellofemoral pain (PFP). DesignCross-sectional. SettingUniversity research laboratory. Participants39 participants with PFP (34.18 ± 7.41years, 170± .1 cm, 81.03 ± 19.36 kg, duration of pain: 68.67 ± 85.08months, anterior knee pain scale: 80.49 ± 7.87, visual analog scale:2.08 ± 2.02) Main outcome measuresAverage 3D hip and knee sagittal, frontal, and transverse joint angles and 2D kFPPA, hFPPA, and DVI at maximum knee flexion were variables of interest. 3D DVI was calculated as the sum of hip and knee frontal and transverse angles. 2D kFPPA, hFPPA, and DVI were calculated by two raters independently on two occasions. ResultsIntra- and inter-rater reliability of all 2D angles were excellent. kFPPA was moderately correlated to 3D knee transverse angles. hFPPA was moderately correlated to 3D hip frontal and transverse angles and largely correlated to 3D DVI. 2D DVI was moderately correlated to hip transverse angles. ConclusionkFPPA, hFPPA, and DVI are reliable. hFPPA may be reflective of 3D hip and knee frontal and transverse motion during forward step-downs in those with PFP.

Structural analysis, mineralogy, and cassiterite U–Pb ages of the Wuxu Sb-Zn-polymetallic district, Danchi Fold-and-Thrust belt, South China

The Danchi fold-and-thrust belt, Guangxi, South China, contains the Mangchang, Dachang, and Wuxu large and giant Sn-polymetallic districts. It hosts more than 1.2 Mt of ore grading 1 % Sn, 6.23 Mt Zn at 2.4 %, and 1.13 Mt Sb at 1.3 %. Wuxu district is one of the Sb-Zn dominated hydrothermal districts without magmatic rocks exposing in the south of the Danchi belt. Recent drilling and exploring mining have identified a partially Sn mineralization associated with the Zn-Sb mineralization. These works provide an opportunity to evaluate the potential of tin mineralization in the south of Danchi belt and relationship among Sn, Zn, and Sb mineralization. Structural analysis suggests that the Wuxu district underwent at least three deformational phases since the Triassic. The first NE-SW shortening deformation controlled the structural framework of the Wuxu district and is expressed by NW-verging thrusts and folds, axial-plane cleavages around the core of the Wuxu anticline, transverse joint sets on the limbs of the Wuxu anticline, and dilational zones in the bedding-fractures. Afterward, an E-W extension stress field produced NS-striking normal faults and reactivated pre-existing NNW-striking faults which were expressed by sinistral top-to-the north sense of shear. During this deformation, some low order dilational spaces of the NW-striking faults and bedding-fractures formed and a syn-kinematic deposition of minerals in these hosting structures to form the ore shoots. The NNW-striking faults, axial-plane cleavages, and large dilational jogs controlled the subvertical large veins in the Jianzhupo deposit. The conjugate joints and inter-bedding fractures in the limb of the Wuxu anticlinorium controlled the branching veinlets and stratiform, paleokarst infilled ores in the Bawang deposit. The post-ore EW-striking faults are not obvious and displaced preceding two-phase structures and ores. Three primary paragenetic stages of hydrothermal process have been recognized: (I) Sphalerite dominated + massive pyrrhotite with euhedral pyrite porphyroblasts, (II) Cassiterite + siderite + arsenopyrite dominated with minor scheelite + quartz + fluorite, and (III) Jamesonite + stibnite + sulfosalt + carbonates. Cassiterite U-Pb dating provided a lower intercept age of 90.2 ± 3.1 Ma and 90.6 ± 4.6 Ma for the Jianzhupo and Bawang deposits, respectively. These two ages are consistent with the chronological data of tin-sulfides and ore-related felsic intrusions in the Danchi fold-and-thrust belt, South China. Our studies coupled with previous gravity data suggests a distal magmatic-hydrothermal infilling tin-polymetallic district and indicates that the Wuxu district has great potential for additional tin mineralization.