Development of an integrated high-voltage electron microscope-gas chromatograph-quadrupole mass spectrometer system for the operando analysis of catalytic gas reactions.

This paper describes the development of a gas chromatography-quadrupole mass spectrometry system attached to a differential-pumping-type environmental cell of the reaction science high-voltage electron microscopy instrument at Nagoya University to distinguish unambiguously between different gas species with the same mass-to-charge ratio. Several model experiments were used to verify the efficacy of the newly proposed system, confirming its ability to analyse the atomic-level structural changes during heterogeneous catalysts and the associated gas-reaction kinetics simultaneously, providing new insights into operando measurements in the field of environmental transmission electron microscopy. Graphical Abstract.

Environmental high-voltage S/TEM combined with a quadrupole mass spectrometer for concurrent in situ structural characterization and detection of product gas molecules associated with chemical reactions.

We introduce herein a combined environmental high-voltage electron microscope and a quadrupole mass spectrometer to detect product gas species associated with chemical reactions occurring in the microscope, which allows new operando experiments of, for instance, observing catalytic reactions by concurrent high-resolution transmission electron microscope (TEM) observation. We demonstrate the preliminary results of redox reactions, where the product gas species are unambiguously detected, associated with the expected structural transformations observed with TEM.

Comparative analysis of medial patellofemoral ligament length change pattern in patients with patellar dislocation using open-MRI.

PURPOSE: Medial patellofemoral ligament (MPFL) reconstruction has become a common form of treatment for recurrent patellar dislocation. This study was performed using open-MRI to compare the length change pattern of MPFL in patients with a history of patellar dislocation to that in healthy subjects. METHODS: The subjects comprised 10 knees of 8 males and 13 knees of 12 females with a history of one or more patellar dislocations. The length of the MPFL was measured using open-MRI in both the leg-extended position and knee-flexed positions to analyse the length change pattern. RESULTS: The average MPFL lengths were 58.6 ± 6.5 mm and 52.0 ± 4.6 mm for males and females in the extended knee position, respectively. The length change pattern of the MPFL showed slight variation up to a flexion angle of 30° and a clear decrease above 30°. This pattern differed from that of normal MPFL. In terms of morphology, the fibre bundle of the damaged MPFL followed a convex course towards the side of the patellofemoral joint surface at a knee flexion angle of 60°, whereas that of the normal MPFL followed a straight course. CONCLUSION: The in vivo damaged MPFL length change pattern was specific and differed distinctly from that of normal MPFL. The results of the present study suggested that MPFL fibres with a history of patellar dislocation lack sufficient tension at knee flexion angles of 0°-60°. However, further studies are needed to obtain a better understanding of cases with a patellar dislocation or postsurgical cases of MPFL reconstruction. LEVEL OF EVIDENCE: III.

A double patella-like condition secondary to synovial osteochondromatosis.

To our knowledge, this is the first case of synovial osteochondromatosis in a patient presenting with a double patella-like condition. The true duplication of the patella, which is called double patella, is extremely rare. In our case, the operative and histopathological findings showed that the double patella-like condition was secondarily induced by synovial osteochondromatosis. Synovial osteochondromatosis should be considered as a differential diagnosis for congenital double patella.

Total knee arthroplasty for neuropathic joint disease after severe bone destruction eroded the tibial tuberosity.

This article describes a patient in whom total knee arthroplasty was performed for neuropathic joint disease secondary to diabetes mellitus after severe bone destruction eroded the tibial tuberosity. At initial examination, radiographs of the knee showed bone destruction in the medial and anterior regions of the tibia, and fine bone fragments were seen in the joint. Conservative therapy was performed using a brace. However, bone destruction gradually advanced, and 10 months after the initial examination, radiographs of the knee showed bone destruction in the lateral condyle of the femur and advanced bone destruction of the anterior tibia; the tibial tuberosity was missing. It is rare for the tibial tuberosity in the anterior tibia to disappear. If this happens, reconstruction is difficult and total knee arthroplasty becomes complicated. For the bone defect in the tibia, cement was used to recreate the shape of the anterior surface of the tibia. It was possible to minimize the volume of bone resection and morphologically reconstruct the tibial tuberosity. The patient recovered quickly. At postoperative week 5, the patient was able to walk using a cane. Thirty-six months after total knee arthroplasty, knee extension was 0°, flexion was 120°, extension lag was 5°, knee score improved from 40 points to 94 points, and functional score improved from 20 points to 75 points. However, long-term implant stability needs to be carefully monitored.

An analysis of the medial patellofemoral ligament length change pattern using open-MRI.

Recently, for a recurrent patellar dislocation, medial patellofemoral ligament (MPFL) reconstruction has come to be commonly performed, yet the precise in vivo MPFL biomechanics still remains to be clarified. The purpose of this study was to analyze the length change pattern of MPFL in vivo. The subjects were comprised of ten male and ten female healthy volunteers. The length of the MPFL was measured using an open-MRI both from a leg extended position and a highly knee-flexed position in order to analyze the length change pattern of the MPFL. The MPFL length for men and women resulted in an average of 52 ± 3 mm and 43 ± 2 mm at the knee extended position, respectively. The length change pattern of the MPFL presented a slight change at up to a flexion angle of 60° and a decrease at over 60°. In terms of morphology, the fiber bundle of the MPFL experienced linear tension at a knee flexion angle of 60°. We determined that the MPFL length in vivo exhibited a specific length change pattern. MPFL mainly contributes to the medial constraint of a patella with a knee flexion of 0° to 60°, wherein it is expected to have the strongest strain at 60°. However, more studies are needed to obtain a better understanding of cases with a history of patellar dislocation.

Transepiphyseal reconstruction of the anterior cruciate ligament in skeletally immature athletes: an MRI evaluation for epiphyseal narrowing.

Reconstructive surgery for anterior cruciate ligament (ACL) injury in skeletally immature athletes presents various clinical problems, because the reconstructive route penetrating both the femoral and tibial physes might cause their growth arrest. Anatomical changes in the physes after ACL reconstruction have not yet been clarified using MRI. Intra-articular ACL reconstructions using femoral and tibial bone tunnels were performed in 10 skeletally immature athletes, who sustained midsubstance ACL tears. The physes of the surgically reconstructed knee and the contralateral knee were compared using MRI obtained 6 months postoperatively. Plain radiography was used to determine the extent of ossification in the tunnel walls. In all patients, MR imaging showed narrowing of the growth plates in the reconstructed knee in comparison with that in the contralateral knee. Radiographic analyses showed corticalization around the drill holes in all cases. Although ACL reconstruction caused narrowing or the early closure of the open physes in adolescents, the patients did not experience limb-length discrepancies and angular deformities.

Time measurement-visual analysis of nickel(II) using autocatalytic reaction with sodium sulfite/hydrogen peroxide system and its application to the length detection-flow analysis.

Trace amounts of nickel(II) can function as a trigger (= reaction initiator) in an autocatalytic reaction with the sodium sulfite/hydrogen peroxide system. Based on this finding, sub-microg L(-1) levels of nickel(II) were determined by a time measurement using the autocatalytic reaction. The detection range using the above method was 10(-9)-10(-5) M, the detection limit (3sigma) was 8.1x10(-10) M (0.047 microg L(-1)), and the relative standard deviation was 2.66% at nickel(II) concentration of 10(-7) M (n = 7). This method was applied to length detection-flow injection analysis. The detection range for the flow injection analysis was 2x10(-9)-2x10(-3) M. The detection limit (3sigma) was 1.4x10(-9) M (0.082 microg L(-1)), and the relative standard deviation was 1.86 at initial nickel(II) concentration of 10(-6) M (n = 7).