Knot impingement after arthroscopic rotator cuff repair mimicking infection: A case report.

BACKGROUND: Knot impingement as a complication after arthroscopic rotator cuff repair (ARCR) has been suggested as a cause of persistent pain with limited motion. We report on a case involving a patient who developed knot impingement after ARCR who complained of acute onset of pain with limited motion, which was confused with infection. CASE SUMMARY: A 55-year-old female who complained of severe pain with limited motion of the right shoulder visited our emergency room. Passive range of motion could not be evaluated due to the patient's severe pain. The patient had undergone ARCR using a suture-bridge technique at a local clinic four months ago for treatment of a small supraspinatus tear of the right shoulder. An erosive change of the undersurface of the acromion was observed on plain radiographs of the right shoulder, and a moderate amount of bursal fluid and synovial thickening with enhancement was observed by magnetic resonance imaging. Results of an analysis of the aspirated fluid showed that the WBC count was 3960 with 90% neutrophils. The arthroscopic view showed healing of the repaired supraspinatus tendon and loose suture threads and knots with severe subacromial bursitis were observed. Debridement of inflammatory tissues of the glenohumeral joint and subacromial space was performed for the removal of all suture materials. The patient's symptoms subsided immediately after the surgical procedure. CONCLUSION: Although the incidence of knot impingement is rare, the possibility of knot impingement after ARCR should be a consideration.

High-Density, Localized Quantum Emitters in Strained 2D Semiconductors.

Two-dimensional chalcogenide semiconductors have recently emerged as a host material for quantum emitters of single photons. While several reports on defect- and strain-induced single-photon emission from 2D chalcogenides exist, a bottom-up, lithography-free approach to producing a high density of emitters remains elusive. Further, the physical properties of quantum emission in the case of strained 2D semiconductors are far from being understood. Here, we demonstrate a bottom-up, scalable, and lithography-free approach for creating large areas of localized emitters with high density (∼150 emitters/um2) in a WSe2 monolayer. We induce strain inside the WSe2 monolayer with high spatial density by conformally placing the WSe2 monolayer over a uniform array of Pt nanoparticles with a size of 10 nm. Cryogenic, time-resolved, and gate-tunable luminescence measurements combined with near-field luminescence spectroscopy suggest the formation of localized states in strained regions that emit single photons with a high spatial density. Our approach of using a metal nanoparticle array to generate a high density of strained quantum emitters will be applied to scalable, tunable, and versatile quantum light sources.

Patch formation on diblock copolymer micelles confined in templates for inducing patch orientation and cyclic colloidal molecules.

HYPOTHESIS: Chemically or physically distinct patches can be induced on the micelles of amphiphilic block copolymers, which facilitate directional binding for the creation of hierarchical structures. Hence, control over the direction of patches on the micelles is a crucial factor to attain the directionality on the interactions between the micelles, particularly for generating colloidal molecules mimicking the symmetry of molecular structures. We hypothesized that direction and combination of the patches could be controlled by physical confinement of the micelles. EXPERIMENTS: We first confined spherical micelles of diblock copolymers in topographic templates fabricated from nanopatterns of block copolymers by adjusting the coating conditions. Then, patch formation was conducted on the confined micelles by exposing them with a core-favorable solvent. Microscopic techniques of SEM, TEM, and AFM were employed to investigate directions of patches and structures of combined micelles in the template. FINDINGS: The orientation of the patches on the micelles was guided by the physical confinement of the micelles in linear trenches. In addition, by confining the micelles in a circular hole, we obtained a specific polygon arrangement of the micelles depending on the number of micelles in the hole, which enabled the formation of cyclic colloidal molecules consisting of micelles.

Porous self-supporting film of semi-flexible supracolloidal chains of diblock copolymer micelles.

Patchy micelles of diblock copolymers can be polymerized into a linear supracolloidal chain. We measure the persistence and contour lengths of supracolloidal chains coated on a solid substrate to evaluate their flexibility. Based on the analysis, the chain is semi-flexible, and the conformation is suitably explained by the worm-like chain model. In addition, utilizing a spin-coating technique with the semi-flexible nature of the chains, we produce a self-supporting film of supracolloidal chains having nanoscale pores essentially from colloidal constituents that tend to form dense packing if there is no prior organization of them into a semi-flexible chain.

Blue emission at atomically sharp 1D heterojunctions between graphene and h-BN.

Atomically sharp heterojunctions in lateral two-dimensional heterostructures can provide the narrowest one-dimensional functionalities driven by unusual interfacial electronic states. For instance, the highly controlled growth of patchworks of graphene and hexagonal boron nitride (h-BN) would be a potential platform to explore unknown electronic, thermal, spin or optoelectronic property. However, to date, the possible emergence of physical properties and functionalities monitored by the interfaces between metallic graphene and insulating h-BN remains largely unexplored. Here, we demonstrate a blue emitting atomic-resolved heterojunction between graphene and h-BN. Such emission is tentatively attributed to localized energy states formed at the disordered boundaries of h-BN and graphene. The weak blue emission at the heterojunctions in simple in-plane heterostructures of h-BN and graphene can be enhanced by increasing the density of the interface in graphene quantum dots array embedded in the h-BN monolayer. This work suggests that the narrowest, atomically resolved heterojunctions of in-plane two-dimensional heterostructures provides a future playground for optoelectronics.

Author Correction: Planar and van der Waals heterostructures for vertical tunnelling single electron transistors.

The original version of this Article contained an error in the spelling of the author Matthew Holwill, which was incorrectly given as Mathew Holwill. This has now been corrected in both the PDF and HTML versions of the Article.

Planar and van der Waals heterostructures for vertical tunnelling single electron transistors.

Despite a rich choice of two-dimensional materials, which exists these days, heterostructures, both vertical (van der Waals) and in-plane, offer an unprecedented control over the properties and functionalities of the resulted structures. Thus, planar heterostructures allow p-n junctions between different two-dimensional semiconductors and graphene nanoribbons with well-defined edges; and vertical heterostructures resulted in the observation of superconductivity in purely carbon-based systems and realisation of vertical tunnelling transistors. Here we demonstrate simultaneous use of in-plane and van der Waals heterostructures to build vertical single electron tunnelling transistors. We grow graphene quantum dots inside the matrix of hexagonal boron nitride, which allows a dramatic reduction of the number of localised states along the perimeter of the quantum dots. The use of hexagonal boron nitride tunnel barriers as contacts to the graphene quantum dots make our transistors reproducible and not dependent on the localised states, opening even larger flexibility when designing future devices.

Fluorescent Supracolloidal Chains of Patchy Micelles of Diblock Copolymers Functionalized with Fluorophores.

By selective attachment of fluorescent dyes to the core-forming block, we produced patchy micelles of diblock copolymers with fluorophores localized in the micellar cores. From these patchy micelles functionalized with dyes, fluorescent supracolloidal chains in a few micrometers were polymerized by combining the patches in neighboring micelles, indicating that selective modification of the core-forming block delivered the functionality into the supracolloidal chain without altering the polymerization of patchy micelles. Thus, with the same polymerization condition, we were able to produce red-, green-, and blue-emitting supracolloidal chains by varying the fluorescent dyes attached to the core-forming block. In addition, we directly visualized individual supracolloidal chains by fluorescence confocal microscopy as well as by transmission electron microscopy.

Supracolloidal chains of patchy micelles of diblock copolymers with in situ synthesized nanoparticles.

Supracolloidal chains of diblock copolymer micelles were functionalized with gold and silver nanoparticles (NPs). Both NPs were independently synthesized in situ in the core of spherical micelles which were then converted to patchy micelles. With these patchy micelles as colloidal monomers, supracolloidal chains were polymerized by combining the patches of neighboring micelles. Since all micelles contained NPs, NPs were incorporated in every repeat unit of chains. In addition, a single gold NP was synthesized in the micellar core in contrast to several silver NPs so that we differentiated the chains with Au NPs from those with Ag NPs by the number of NPs in the repeat unit as well as by plasmonic bands in UV-Vis spectra.

Branched and crosslinked supracolloidal chains with diblock copolymer micelles having three well-defined patches.

We report controlled branching and eventual crosslinking in supracolloidal chains by introducing well-defined trifunctional patchy micelles. Uniform micelles having three patches were induced from core-crosslinked micelles of diblock copolymers. Three patches in the micelles served as functional groups for crosslinking as well as branching in supracolloidal polymerization.

False negative rate of syndesmotic injury in pronation-external rotation stage IV ankle fractures.

BACKGROUND: To investigate false negative rate in the diagnosis of diastasis on initial static anteroposterior radiograph and reliability of intraoperative external rotational stress test for detection of concealed disruption of syndesmosis in pronation external rotation (PER) stage IV (Lauge-Hansen) ankle fractures. MATERIALS AND METHODS: We prospectively studied 34 PER stage IV ankle fractures between September 2001 and September 2008. Twenty (59%) patients show syndesmotic injury on initial anteroposterior radiographs. We performed an intraoperative external rotation stress test in other 14 patients with suspicious PER stage IV ankle fractures, which showed no defined syndesmotic injury on anteroposterior radiographs inspite of a medial malleolar fracture, an oblique fibular fracture above the syndesmosis and fracture of the posterior tubercle of the tibia. RESULTS: All 14 fractures showed different degrees of tibiofibular clear space (TFCS) and tibiofibular overlapping (TFO) on the external rotation stress test radiograph compared to the initial plain anteroposterior radiograph. It is important to understand the fracture pattern characterstic of PER stage IV ankle fractures even though it appears normal on anteroposterior radiographs, it is to be confirmed for the concealed syndesmotic injury through a routine intraoperative external rotational stress radiograph.