Form Factor-Free Boron Nitride Nanotube-Agarose Composites for Neutron Shielding.

Boron nitride nanotubes (BNNTs) have remarkable mechanical and thermal properties and are suitable for neutron shielding due to boron. Because BNNTs exist in bundled and stiff shapes, limiting their practical applications, however, it is essential to improve their formability and processability. In this study, we demonstrate form-factor-free BNNTs and agarose composites for use in neutron shielding for the first time; they are fabricated by mixing hydrophilic agarose with noncovalently functionalized water-soluble BNNTs (p-BNNTs). The mechanical properties of the agarose/p-BNNT composite films surpass those of conventional commodity plastics. When the p-BNNT concentration increased, the neutron linear attenuation coefficient of the composite film increases from 0.574 ± 0.010 to 0.765 ± 0.062 mm-1, which is comparable to that of conventional rigid shielding materials. In particular, the addition of 10 wt % p-BNNTs to agarose results in excellent form-factor flexibility, neutron shielding, and mechanical properties, thus rendering it a promising candidate for the nuclear industry.

A Comparative Study on Outcomes of Partial Meniscectomy for Horizontal Cleavage Tear of Medial Meniscus: Complete versus Partial Resection of Inferior Leaf.

The extent to which resection of unstable leaf should be performed in horizontal cleavage meniscus tear has not yet been elucidated. The purpose of this study was to compare the clinical outcomes of partial meniscectomy for horizontal cleavage tear of medial meniscus between complete resection of inferior leaf including the periphery up to the joint capsule and partial resection leaving stable peripheral torn meniscal tissue. A total of 126 patients who underwent partial meniscectomy for horizontal cleavage tear of medial meniscus were divided into two groups: group C (n = 34), treated with the complete resection of the inferior leaf; and group P (n = 92), treated with partial resection of the inferior leaf. The minimum follow-up duration was 3 years. Functional outcomes were evaluated using the Lysholm knee scoring scale, International Knee Documentation Committee (IKDC) subjective knee evaluation form, and knee injury and osteoarthritis outcome score (KOOS). Radiologic assessments were performed using the IKDC radiographic assessment scale and measurement of the height of the joint space in the medial compartment of the tibiofemoral joint. The functional outcomes including the Lysholm knee, IKDC subjective score, activities of daily living and sport and recreation subscale of KOOS were worse in group C than in group P (p < 0.001). The radiologic outcomes including postoperative IKDC radiographic scale (p = 0.003) and the postoperative joint space on the affected side (p < 0.001) were also worse in group C than in group P. In the horizontal cleavage tear of medial meniscus, complete resection of the inferior leaf including the periphery up to the joint capsule showed inferior clinical outcomes compared with partial resection leaving stable peripheral rim of torn meniscus at minimum 3-year follow-up. If the peripheral part of the inferior leaf is stable in horizontal cleavage tear of medial meniscus, partial resection of the inferior leaf preserving peripheral rim can be recommended.

Unusual Self-Assembly of Amphiphilic Block Copolymer Blends Induced by Control of Hydrophobic Interaction.

Block copolymer blend systems have been of great interest for a wide range of potential applications, such as nanobuilding blocks or guidance materials, because they can provide a rich phase behavior according to external conditions. However, a new and unique phase behavior of block copolymers, which can give us their more extended potential applications, has not yet been reported. Herein, we report the unusual self-assembly of two different types of Pluronic P65 and PE6200 triblock copolymer blends dependent on temperature and PE6200 concentration, which is unique for the block copolymer blends in aqueous solution. As the temperature and concentration of PE6200 (as an additive) increased, the Pluronic P65/PE6200 copolymer blends sequentially self-assembled into an isotropic micellar-hexagonal-isotropic micellar or isotropic micellar-hexagonal-isotropic micellar-lamellar phase, which is a discontinuous ordered phase (called a closed looplike phase transition), and their phase transition temperature could be controlled. To the best of our knowledge, this is the first report of a closed looplike phase transition of Pluronic block copolymer blends in aqueous solution, which can be easily applied to nanosized templates for temperature-selective highly ordered structures and optical devices such as optoelectronics or optical sensors.

Molecular Weight-Dependent, Flexible Phase Behaviors of Amphiphilic Block Copolymer/Additive Complexes in Aqueous Solution.

Pluronic amphiphilic block copolymers, well known to have a phase behavior can be controlled by external conditions, have a wide range of potential for applications such as nanotemplates or nanobuilding blocks. However, the phase behaviors of Pluronic block copolymer/additive complexes with highly ordered phases have not been fully investigated. Here, we report the unusual molecular weight-dependent self-assembly of Pluronic block copolymer/additive complexes. Depending on the temperature and additive, Pluronic P65 block copolymer with a lower molecular weight showed the closed loop-like (CLL) phase behavior with the disorder-order-disorder-order phase transition in aqueous solution, whereas Pluronic P105 and P85 block copolymers with higher molecular weights underwent highly ordered continuous phase transitions with face centered cubic (FCC), hexagonal, and lamellar phases. It is expected that the specific phase behavior of the block copolymer/additive complex can be applied in optical devices such as nanotemplates or optical sensors for a highly ordered superlattice. Furthermore, this study provides a new route to control the phase behavior of the block copolymers without a complicated process.

Factors Related to Meniscal Extrusion and Cartilage Lesions in Medial Meniscus Root Tears.

The purpose of this study was to identify factors affecting medial meniscus extrusion and cartilage degeneration in medial meniscus root tears (MMRT) and to determine the optimal cut-off values for the factors that predict disease severity. We retrospectively evaluated 86 consecutive patients diagnosed with an isolated MMRT by magnetic resonance imaging (MRI) examinations and arthroscopic procedures for 2 years. Patient-specific factors such as age, sex, the time between injury and MRI (mTIME), the time between injury and surgery (sTIME), the time between MRI and surgery (dTIME), Kellgren-Lawrence (KL) grades, and the mechanical tibiofemoral axis angle (mTFA) were documented. Regression analyses and receiver operating characteristic (ROC) curve analyses were performed. The mTIME was only positively correlated with meniscal extrusion (r = 0.425, p < 0.001). The patients who had grades 3 and 4 cartilage lesions had only significantly higher KL grades and longer sTIME than the patients who had lower grades of cartilage lesion (6.5 months [interquartile range (IQ): 3.0-12.0) vs. 2.5 months [IQ: 0.9-3.9]; p < 0.001). The cut-off value of mTIME and sTIME were 2.5 and 6 months. Relapse times greater than 2.5 months and 6 months after a specific event were associated with a 7.8-fold increased risk for meniscus extrusion and an 18.2-fold increased risk for cartilage lesions, respectively. The risk of medial extrusion of the meniscus and the severity of articular cartilage lesions increased with time after an injury. The period of time from 2.5 to 6 months after traumatic event might be a critical window for intervention in the patients with MMRT to perform the repair in the status which the meniscus did not extrude more than 3 mm and the cartilage lesion did not progress more than grade 3. This study is a retrospective and uncontrolled case series and reflects level IV of evidence.

Medial Meniscus Posterior Root Tear Does Not Affect the Outcome of Medial Open-Wedge High Tibial Osteotomy.

BACKGROUND: This study aimed to verify whether the presence of medial meniscus posterior root tear (MMPRT) affects the clinical and radiographic outcomes of medial open-wedge high tibial osteotomy (MOWHTO) compared to the patients without MMPRT for over a midterm follow-up. METHODS: One hundred fifty-six knees were retrospectively enrolled that underwent MOWHTO and second-look arthroscopy concomitantly with a minimum 5 years of follow-up. Seventy-four knees with MMPRT (MMPRT group) were identified. Eighty-two knees with intact MMPR were assigned to another group (MMPRI group). All knees with torn medial meniscus with or without MMPRT had an arthroscopic partial meniscectomy during the MOWHTO. Clinical evaluation included range of motion, American Knee Society scores, and Western Ontario and McMaster Universities Osteoarthritis Index scores. Radiologically, the Kellgren-Lawrence grade was assessed preoperatively and at the latest follow-up. Cartilage status was also compared through the 2-stage arthroscopy according to the International Cartilage Repair Society grading. RESULTS: Average age at operation was 55.8 years (range 42-67), and the average follow-up period was 82.2 months (range 60-148). There were no significant differences in clinical outcomes between the groups. Postoperative changes in Kellgren-Lawrence grade and arthroscopic cartilage status showed no significant differences between the groups. Resected MMPR was remodeled in 41.9% (31/74) of the MMPRT group through the second-look arthroscopy. CONCLUSION: MMPRT does not affect the clinical and radiologic outcomes of MOWHTO compared to those patients without MMPRT over a mid-term follow-up.

Noncanonical Head-to-Head Hairpin DNA Dimerization Is Essential for the Synthesis of Orange Emissive Silver Nanoclusters.

DNA secondary structures, such as dimers and hairpins, are important for the synthesis of DNA template-embedded silver nanoclusters (DNA/AgNCs). However, the arrangement of AgNCs within a given DNA template and how the AgNC influences the secondary structure of the DNA template are still unclear. Here, we introduce a noncanonical head-to-head hairpin DNA nanostructure that is driven by orange-emissive AgNCs. Through detailed in-gel analysis, sugar backbone switching, inductively coupled plasma mass spectrometry, small-angle X-ray scattering, and small angle neutron scattering, we show that the orange-emissive AgNCs mediate cytosine-Ag-cytosine bridging between two six-cytosine loop (6C-loop) hairpin DNA templates. Unlike green, red, or far-red emissive AgNCs, which are embedded inside a hairpin and duplex DNA template, the orange-emissive AgNCs are localized on the interface between the two 6C-loop hairpin DNA templates, thereby linking them. Moreover, we found that deoxyribose in the backbone of the 6C-loop at the third and fourth cytosines is crucial for the formation of the orange-emissive AgNCs and the head-to-head hairpin DNA structure. Taken together, we suggest that the specific wavelength of AgNCs fluorescence is determined by the mutual interaction between the secondary or tertiary structures of DNA- and AgNC-mediated intermolecular DNA cross-linking.

Fabrication of Noncovalently Functionalized Boron Nitride Nanotubes with High Stability and Water-Redispersibility.

Boron nitride nanotubes (BNNTs) have attracted significant interest because of the remarkable difference in their physical properties compared with carbon nanotubes and their far-reaching potential applications, including electrical insulators; thermally conducting, catalytic, and piezoelectric materials; and neutron absorbers. Despite their unique physical properties, the bundling and insolubility of BNNTs in water because of its substantial van der Waals attraction and hydrophobicity, respectively, give rise to many limitations in practical applications. Here, we present a new way to produce a highly stable BNNT dispersion by the noncovalent functionalization of the BNNT surface in water. The noncovalently functionalized BNNTs (p-BNNTs) have been found to be highly stable in water for a long time (>1 year) and easily water-redispersible by mild vortex mixing for a few minutes even after freeze-drying at -45 °C. The p-BNNTs were cylindrically encapsulated with polymerizable surfactants (BNNT diameter = ca. 3 nm and surfactant thickness = 0.8 nm).

Robot-Assisted Total Knee Arthroplasty Does Not Improve Long-Term Clinical and Radiologic Outcomes.

BACKGROUND: Whether robot-assisted total knee arthroplasty (TKA) improves the accuracy of radiographic alignment leading to improved patient satisfaction and implant survivorship in the long term has thus far been inconclusive. METHODS: We retrospectively compared the long-term clinical and radiological outcomes of 84 knees that had undergone robot-assisted TKA using ROBODOC vs 79 knees that had undergone conventional TKA. The mean duration of the follow-up period was 129.1 months (range: 108-147 months). Clinical outcomes were evaluated using the Knee Society Score and 36-item Short Form Survey, as well as by assessing the range of motion, operation time, and complications. Radiologic outcomes were evaluated by assessing the hip-knee-ankle angle, coronal and sagittal alignments of the femoral and tibial components, and any radiologic abnormalities such as loosening or osteolysis. RESULTS: There was no significant difference in clinical outcomes between the two groups. The prevalence of an outlier for the hip-knee-ankle angle in the robot-assisted group was 10.7%, whereas it was 16.5% in the conventional group (P = .172). The other component alignments (α°, ß°, γ°, δ°) revealed a tendency toward a lower rate of outliers in the robot-assisted group, but without statistical significance (P > .05). In addition, there was no significant difference in complications, including revision surgery, between both groups. CONCLUSION: Robot-assisted TKA does not improve long-term clinical or radiologic outcomes compared with conventional TKA.

Dispersion of Boron Nitride Nanotubes by Pluronic Triblock Copolymer in Aqueous Solution.

Boron nitride nanotubes (BNNTs) have been of interest for their excellent thermal, electrical, and mechanical properties, and they have a broad spectrum of potential applications, such as in piezoelectric materials, reinforcement of materials, and electrothermal insulation materials. For practical use of BNNTs, it is desirable to disperse them in aqueous solution, which improves convenience of handling. However, it is still difficult to make a homogenous and stable BNNT dispersion in aqueous solution, due to their strong van der Waals interactions and hydrophobic surface. To solve these problems, we used Pluronic P85 and F127, which have both hydrophilic groups and hydrophobic groups. Here, we report the wrapped structure of a Pluronic polymer-BNNT dispersion by using small-angle neutron scattering, UV⁻Vis spectroscopy, thermogravimetric analysis, and atomic force microscopy.

The Fate of the Contralateral Knee in Patients With a Lateral Discoid Meniscus.

PURPOSE: To analyze the survivorship of the lateral meniscus (LM) in the contralateral knee after surgery for symptomatic torn discoid lateral meniscus (DLM) and to determine its associated factors. METHODS: Two hundred ninety-six patients who underwent arthroscopic meniscectomy for torn symptomatic DLM were reviewed retrospectively. Patients were classified into subgroups based on demographic, clinical, and radiologic variables. The survivorship analysis of the LM on the contralateral knee was calculated using the Kaplan-Meier method, and comparison among the subgroups was conducted using the log-rank test. The predicted prognostic factors associated with survivorship were determined using Cox proportional hazard regression analysis. RESULTS: Of the 296 patients, 51 (17%) had arthroscopic surgery in the contralateral knee during the study period. The group ≥40 years old had significantly worse survival than the group <40 (log-rank test, P < .001). In terms of radiologic variables, the group with Kellgren-Lawrence grade 3 or 4 had significantly poorer survivorship than that with grade 1 or 2 (log-rank test, P = .045). Age ≥40 years was associated with poorer survivorship (hazard ratio, 3.235; 95% confidence interval, 1.782-5.875; P < .001). Kellgren-Lawrence grades 3 and 4 in the contralateral knee were associated with poorer survival (hazard ratio, 2.071; 95% confidence interval, 1.061-4.043; P = .033). The cumulative survival rate at 10 years of the LM in the contralateral knee after surgery for symptomatic torn DLM was 81%. CONCLUSIONS: Patients with a lateral discoid meniscus have a risk of a similar condition in the contralateral knee. Increased risks of symptomatology are associated with age and degenerative changes. LEVEL OF EVIDENCE: Level IV, retrospective uncontrolled case series.

The percutaneous pie-crusting medial release during arthroscopic procedures of the medial meniscus does neither affect valgus laxity nor clinical outcome.

PURPOSE: To analyze the effect of percutaneous pie-crusting medial release on valgus laxity before and after surgery and on clinical outcomes. METHODS: Eight-hundred fourteen consecutive patients who underwent an arthroscopic procedure for the medial compartment of the knee were evaluated retrospectively. Sex, age, type of operation (meniscectomy, meniscal repair, and posterior root repair), type of accompanying surgery (none, cartilage procedure, ligament procedure and osteotomy) were documented. Sixty-four patients who underwent percutaneous pie-crusting medial release (release group) and 64 who did not undergo medial release (non-release group) were matched using the propensity score method. Each patient was evaluated for the following variables: degree of valgus laxity on stress radiographs, Lysholm knee score, visual analog scale score, and International Knee Documentation Committee knee score and grade. RESULTS: At the 24-month follow-up, no significant increase in side-to-side differences in the valgus gap was observed in comparison to the preoperative value in the release group [preoperative, - 0.1 ± 1.3 mm; follow-up, - 0.1 ± 1.4 mm; (n.s.)]. The follow-up Lysholm score, visual analog scale score and International Knee Documentation Committee knee score and grade were similar between the two groups. CONCLUSIONS: Percutaneous pie-crusting medial release is an additional procedure that can be performed during arthroscopic surgery for patients with a narrow medial joint space of the knee. Percutaneous pie-crusting medial release reduces iatrogenic injury to the cartilage and does not produce any residual valgus laxity of the knee. LEVEL OF EVIDENCE: IV.

Passive skeletal muscle excursion after tendon rupture correlates with increased collagen content in muscle.

PURPOSE: This study was designed to measure time-dependent changes in muscle excursion and collagen content after tenotomy, and to analyze the correlation between muscle excursion and collagen content in a rabbit model. MATERIALS AND METHODS: Twenty-four rabbits underwent tenotomy of the second extensor digitorum longus (EDL) muscles on the right legs and were randomly assigned to three groups based on the period of time after tenotomy (2, 4, and 6 weeks). The second EDL muscles on left legs were used as controls. At each time after tenotomy, passive muscle excursion and collagen content, determined by hydroxyproline content, were measured bilaterally, and the ratio of each value to the normal one was used. RESULTS: The mean ratio of muscle excursion after tenotomy to the value of the control decreased in a time-dependent fashion: 92.5% at 2 weeks, 78.6% at 4 weeks, and 55.1% at 6 weeks. The mean ratio of hydroxyproline content in muscle to the value of the control increased in a time-dependent fashion: 119.5% at 2 weeks, 157.3% at 4 weeks, and 166.6% at 6 weeks. There was a significant negative correlation between the ratio of hydroxyproline content in muscle after tenotomy to the control values and the ratio of muscle excursion after tenotomy to the control values (r=-0.602, p=0.002). CONCLUSION: The decrease in muscle excursion seems to correlate with the increase in collagen content in the muscle in a time-dependent fashion following tenotomy.