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Tissue and biomaterial microenvironments provide architectural cues that direct important cell behaviors including cell shape, alignment, migration, and resulting tissue formation. These architectural features may be presented to cells across multiple length scales, from nanometers to millimeters in size. In this study, we examined how architectural cues at two distinctly different length scales, “micro-scale” cues on the order of ∼1–2 μm, and “meso-scale” cues several orders of magnitude larger (>100 μm), interact to direct aligned neo-tissue formation. Utilizing a micro-photopatterning (μPP) model system to precisely arrange cell-adhesive patterns, we examined the effects of substrate architecture at these length scales on human mesenchymal stem cell (hMSC) organization, gene expression, and fibrillar collagen deposition. Both micro- and meso-scale architectures directed cell alignment and resulting tissue organization, and when combined, meso cues could enhance or compete against micro-scale cues. As meso boundary aspect ratios were increased, meso-scale cues overrode micro-scale cues and controlled tissue alignment, with a characteristic critical width (∼500 μm) similar to boundary dimensions that exist in vivo in highly aligned tissues. Meso-scale cues acted via both lateral confinement (in a cell-density-dependent manner) and by permitting end-to-end cell arrangements that yielded greater fibrillar collagen deposition. Despite large differences in fibrillar collagen content and organization between μPP architectural conditions, these changes did not correspond with changes in gene expression of key matrix or tendon-related genes. These findings highlight the complex interplay between geometric cues at multiple length scales and may have implications for tissue engineering strategies, where scaffold designs that incorporate cues at multiple length scales could improve neo-tissue organization and resulting functional outcomes. [ABSTRACT FROM AUTHOR]

This article discusses the creation of a student project about linear difference equations using primary sources. Early 18th-century developments in the area are outlined, focusing on efforts by Abraham De Moivre (1667–1754) and Daniel Bernoulli (1700–1782). It is explained how primary sources from these authors can be used to cover material appearing in most discrete mathematics courses while revealing how the mathematical ideas evolved. It is argued that this project works well in a discrete mathematics course that also makes the transition to higher mathematics, developing mathematical reading and writing skills in a natural setting. [ABSTRACT FROM PUBLISHER]

Scaphoid fractures occur commonly in the athlete and should be treated with urgency to avoid undesired late complications. Magnetic resonance imaging may be helpful to make a prompt diagnosis so that an appropriate early treatment plan can be initiated. Cast immobilization in acute, nondisplaced scaphoid fractures seems to have an equivalent union rate to surgical modalities. Despite this, limiting the immobilization and time to union period in the athlete will allow earlier restoration of preinjury level function and eventual return to play. Percutaneous techniques with or without arthroscopy assistance have been advocated as less invasive surgical approaches that may have an added benefit in the athlete. Displaced and unstable fractures should be approached with a volar or dorsal open technique to achieve and confirm an anatomic reduction before screw placement. [ABSTRACT FROM AUTHOR]

In this paper, we outline a method for constructing nonnegative scaling vectors on the interval. Scaling vectors for the interval have been constructed in [1-3]. The approach here is different in that the we start with an existing scaling vector Φ that generates a multi-resolution analysis for L²(ℝ.) to create a scaling vector for the interval. If desired, the scaling vector can be constructed so that its components are nonnegative. Our construction uses ideas from [4,5] and we give results for scaling vectors satisfying certain support and continuity properties. These results also show that less edge functions are required to build multi-resolution analyses for L² ([a; b]) than the methods described in [5,6]. [ABSTRACT FROM AUTHOR]

BACKGROUND: Distal radial fractures with extensive comminution involving the metaphyseal-diaphyseal junction present a major treatment dilemma. Of particular difficulty are those fractures involving the articular surface. One approach is to apply a dorsal 3.5-mm plate extraarticularly from the radius to the third metacarpal, stabilizing the diaphysis and maintaining distraction across the radiocarpal joint. METHODS: Twenty-two patients treated with a distraction plate for a comminuted distal radial fracture were included in the study. With use of three limited incisions, a 3.5-mm ASIF plate was applied in distraction dorsally from the radial diaphysis, bypassing the comminuted segment, to the long-finger metacarpal, where it was fixed distally. The articular surface was anatomically reduced and was secured with Kirschner wires or screws. Eleven of the twenty-two fractures were treated with bone-grafting. The plate was removed after fracture consolidation (at an average of 124 days), and wrist motion was initiated. All patients were followed prospectively with use of radiographs, physical examination, and DASH (Disabilities of the Arm, Shoulder and Hand) scores. RESULTS: All fractures united by an average of 110 days. Radiographs showed an average palmar tilt of 4.6° and an average ulnar variance of neutral (0°), whereas loss of radial length averaged 2 mm. Flexion and extension averaged 57° and 65°, respectively, and pronation and supination averaged 77° and 76°, respectively. The average DASH scores were 34 points at six months, 15 points at one year, and 11.5 points at the time of final follow-up (at an average of 24.8 months). According to the Gartland-Werley rating system, fourteen patients had an excellent result, six had a good result, and two had a fair result. Grip strength and the range of motion of the wrist at one year correlated inversely with the proximal extent of fracture comminution into the diaphysis. The duration of plate immobilization did not correlate with the range of motion of the wrist or with the DASH score at one year. CONCLUSIONS: The use of a distraction plate combined with reduction of the articular surface and bone-grafting when needed can be an effective technique for treatment of fractures of the distal end of the radius with extensive metaphyseal and diaphyseal comminution. A functional range of motion with minimal disability can be achieved despite a prolonged period of fixation with a distraction plate across the wrist joint. [ABSTRACT FROM AUTHOR]

Background: Distal radial fractures with extensive comminution involving the metaphyseal-diaphyseal junction present a major treatment dilemma. Of particular difficulty are those fractures involving the articular surface. One approach is to apply a dorsal 3.5-mm plate extra-articularly from the radius to the third metacarpal, stabilizing the diaphysis and maintaining distraction across the radiocarpal joint. Methods: Twenty-two patients treated with a distraction plate for a comminuted distal radial fracture were included in the study. With use of three limited incisions, a 3.5-mm ASIF plate was applied in distraction dorsally from the radial diaphysis, bypassing the comminuted segment, to the long-finger metacarpal, where it was fixed distally. The articular surface was anatomically reduced and was secured with Kirschner wires or screws. Eleven of the twenty-two fractures were treated with bone-grafting. The plate was removed after fracture consolidation (at an average of 124 days), and wrist motion was initiated. All patients were followed prospectively with use of radiographs, physical examination, and DASH (Disabilities of the Arm, Shoulder and Hand) scores. Results: All fractures united by an average of 110 days. Radiographs showed an average palmar tilt of 4.6° and an average ulnar variance of neutral (0°), whereas loss of radial length averaged 2 mm. Flexion and extension averaged 57° and 65°, respectively, and pronation and supination averaged 77° and 76°, respectively. The average DASH scores were 34 points at six months, 15 points at one year, and 11.5 points at the time of final follow-up (at an average of 24.8 months). According to the Gartland­Werley rating system, fourteen patients had an excellent result, six had a good result, and two had a fair result. Grip strength and the range of motion of the wrist at one year correlated inversely with the proximal extent of fracture comminution into the diaphysis. The duration of plate immobilization did not correlate with the range of motion of the wrist or with the DASH score at one year. Conclusions: The use of a distraction plate combined with reduction of the articular surface and bone-grafting when needed can be an effective technique for treatment of fractures of the distal end of the radius with extensive metaphyseal and diaphyseal comminution. A functional range of motion with minimal disability can be achieved despite a prolonged period of fixation with a distraction plate across the wrist joint. Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Abstract: This paper considers Gibbs'' phenomenon for scaling vectors in . We first show that a wide class of multiresolution analyses suffer from Gibbs'' phenomenon. To deal with this problem, in [Contemp. Math. 216 (1998) 63–79], Walter and Shen use an Abel summation technique to construct a positive scaling function , , from an orthonormal scaling function φ that generates . A reproducing kernel can in turn be constructed using . This kernel is also positive, has unit integral, and approximations utilizing it display no Gibbs'' phenomenon. These results were extended to scaling vectors and multiwavelets in [Proceedings of Wavelet Analysis and Multiresolution Methods, 2000, pp. 317–339]. In both cases, orthogonality and compact support were lost in the construction process. In this paper we modify the approach given in [Proceedings of Wavelet Analysis and Multiresolution Methods, 2000, pp. 317–339] to construct compactly supported positive scaling vectors. While the mapping into associated with this new positive scaling vector is not a projection, the scaling vector does produce a Riesz basis for and we conclude the paper by illustrating that expansions of functions via positive scaling vectors exhibit no Gibbs'' phenomenon. [Copyright &y& Elsevier]

Background: Controlled joint extension followed by gradual distraction with use of an external fixator may facilitate primary repair of peripheral nerve defects by permitting end-to-end repair without tension. The hypothesis of the present study was that gradual lengthening of nerve repairs with use of incremental distraction would provide superior results compared with grafting or repair under tension. Methods: A median nerve segment measuring four times the diameter of the nerve was resected in thirty-six rabbits to create a 7-mm gap in the nerve. Neurorrhaphy was performed with use of one of three techniques. In Group 1 (cable graft), a tension-free medial antebrachial cutaneous graft was placed to allow full range of motion of the elbow postoperatively. In Group 2 (end-to-end repair without distraction), the elbow was externally fixed in hyperflexion and the nerve was repaired end-to-end. At fourteen days, the fixator was removed and unprotected elbow motion was permitted. In Group 3 (end-to-end repair with gradual distraction), the elbow was externally fixed in hyperflexion and primary neurorrhaphy was performed. At fourteen days, the elbow was extended 10° every other day with use of the articulated external fixator until full extension was achieved. Median nerve amplitude, latency, and nerve-conduction velocity; flexor digitorum superficialis single-twitch force generation and maximum tetanic force generation; muscle mass; and elbow range of motion were measured at three or six months. In addition, histologic analysis of the median nerve distal to the repair site and the morphometry of the neuromuscular junction in the flexor digitorum superficialis were performed at six months. Results: All rabbits regained full active and passive range of motion. At three months, the nerve-conduction velocities in Groups 2 and 3 were significantly greater than that in Group 1. At six months, the nerve-conduction velocities and amplitudes in Group 3 were significantly greater than those in Groups 1 and 2. At six months, the tetanic force in Group 3 was significantly greater than those in Groups 1 and 2. There were no significant differences in muscle mass among the groups. There were no significant differences in histological findings among the three groups, although there was a trend toward larger fiber size in Group 3 as compared with the other two groups. The neuromuscular junctions in Group 3 had a significantly larger surface area than did those in Group 1 (p = 0.002) and Group 2 (p = 0.034). Conclusion: The use of an articulated external fixator and controlled gradual distraction appears to facilitate the treatment of peripheral nerve defects. Clinical Relevance: This nerve repair technique may prove useful in clinical situations involving peripheral nerve defects. [ABSTRACT FROM AUTHOR]

Conventional functionalization methods, such as oxidation, can be very damaging for the nanocarbons microstructure and therefore detrimental for their intrinsic thermal conductivity. In this study, nitrene chemistry was investigated as a non-disruptive approach for the covalent functionalization of graphene nanoplatelets (GNP). The nitrene precursor was synthesized and thermally decomposed in situ to functionalize GNP (cm-GNP). Temperature and solvents of reaction were found to have profound impact on the functionalization yield. Epoxy nanocomposites were then prepared with pristine, oxidized and cm-GNP. Influence of dispersion methodology was crucial for cm-GNP, as sonication was found to damage the functionalization. Oxidation caused a dramatic drop in thermal conductivity compared to pristine GNP. By contrast, nitrene chemistry produced the highest thermal conductivity enhancement. Finally, epoxy nanocomposites thermal conductivity results were correlated and discussed in light of SEM and micro-computed X-ray tomography (μCT) analyses. The μCT highlighted new features, such as micro-voids surrounding pristine GNP in epoxy nanocomposites, which are invisible with conventional methods. It was found that functionalization not only enhanced the dispersion but also improved GNP/polymer interactions. Moreover, μCT clearly demonstrated that nitrene functionalization eliminated the micro voids surrounding the fillers in the epoxy nanocomposites. Image 1 [ABSTRACT FROM AUTHOR]

Case: The lateral ulnar collateral ligament (LUCL) is one of the primary stabilizers of the elbow. Disruption typically occurs from the humeral origin and may be because of an elbow dislocation or fracture/dislocation. If not identified and properly managed, posterolateral rotatory instability may result from LUCL insufficiency. We describe the case of a patient with bipolar LUCL disruption consisting of an avulsion fracture of the crista supinatoris and a soft-tissue avulsion from the lateral epicondyle. Conclusion: Bipolar disruption of the LUCL is a previously unreported injury pattern that may lead to posterolateral instability if not identified and treated. [ABSTRACT FROM AUTHOR]

Case: Massive bone loss around the elbow is a challenging clinical condition. Short periarticular osseous segments present few reconstructive options in the setting of distal humerus bone loss. We report the case of a 20-year-old man who sustained an open, intra-articular distal humerus fracture with a massive metaphyseal defect of 15 cm after a motorcycle accident. The defect was reconstructed using an induced membrane technique with temporary ulnohumeral bridge plate stabilization. Conclusion: Temporary ulnohumeral spanning plate fixation is a reliable method for periarticular reconstruction in the setting of massive distal humerus bone loss. [ABSTRACT FROM AUTHOR]

Suggests the use of graphing calculators as an alternative approach to solving equilibrium problems in chemistry. Method of successive approximations (MSA); Portability and user-friendliness; Use in precalculus and calculus courses.

An introduction is presented in which the editor discusses reports within the issue on topics related to hand and wrist injuries in sports medicine including a comparison between immediate treatment and delayed treatment as well as the concept of early operative management.

Polydimethylsiloxane (PDMS) adhesive films have increasingly attracted attention due to their inherent properties such as biocompatibility, high flexibility, optical transparency, and many others. In this contribution, dopamine‐functionalized polydimethylsiloxane polymer conetworks prepared from poly(pentafluorophenyl acrylate)‐l‐polydimethylsiloxane (PFPA‐l‐PDMS) amphiphilic polymer conetwork precursors are proposed. This straightforward approach gives easy access to polydopamine‐functionalized PDMS polymer conetworks with a different composition, stiffness of the polymer conetwork, and their corresponding nanoscale phase‐separated morphologies. The adhesive property of the polymer films on the glass substrate obtained by lap shear testing gives a maximum adhesive strength of 0.85 ± 0.08 MPa thanks to phase‐separated morphologies at the nanometer scale and the high flexibility inherent to polysiloxane. The proposed approach provides an easy and straightforward way to introduce dopamine into a polymer conetwork with tunable adhesive properties. [ABSTRACT FROM AUTHOR]

Triple-shape polymers can memorize two independent shapes during a controlled recovery process. This work reports the 4D printing of electro-active triple-shape composites based on thermoplastic blends. Composite blends comprising polyester urethane (PEU), polylactic acid (PLA), and multiwall carbon nanotubes (MWCNTs) as conductive fillers were prepared by conventional melt processing methods. Morphological analysis of the composites revealed a phase separated morphology with aggregates of MWCNTs uniformly dispersed in the blend. Thermal analysis showed two different transition temperatures based on the melting point of the crystallizable switching domain of the PEU (Tm~50 ± 1 °C) and the glass transition temperature of amorphous PLA (Tg~61 ± 1 °C). The composites were suitable for 3D printing by fused filament fabrication (FFF). 3D models based on single or multiple materials were printed to demonstrate and quantify the triple-shape effect. The resulting parts were subjected to resistive heating by passing electric current at different voltages. The printed demonstrators were programmed by a thermo-mechanical programming procedure and the triple-shape effect was realized by increasing the voltage in a stepwise fashion. The 3D printing of such electroactive composites paves the way for more complex shapes with defined geometries and novel methods for triggering shape memory, with potential applications in space, robotics, and actuation technologies. [ABSTRACT FROM AUTHOR]

Copyright of Southern Medical Journal is the property of Lippincott Williams & Wilkins and Its content may not be copied or emailed to multiple sites or posted to a listserv without the Copyright holder's express written permission. [Extracted from the article]

An abstract of the article "Correlation Of Arteriography With Scanning Laser Doppler" by Albert W. Marr and colleagues is presented.

An abstract of the article "Innervation Density Of The Palm: The Quest For The Perfect Carpal Tunnel Release" by Albert W. Marr and colleagues is presented.

A letter to the editor is presented in response to the article "Collision-induced cage folding of partially condensed polyhedral oligomeric silsesquioxanes (POSS) bearing naked and capped silanols."

Highlights: [•] In this paper, we study the adhesive, water resistance and thermo-mechanical properties of a bio-based DGEBA substitution candidate issued from Cardanol. [•] Bio-based networks outperformed the conventional epoxy in terms of adhesion and water uptake, representing interesting alternatives for applications close to ambient temperature. [•] An unconventional relationship between water uptake by the biobased adhesive and property loss due to plasticization was uncovered. [Copyright &y& Elsevier]

Abstract: Composite free standing membranes made by solvent casting of polyaniline (PANI) synthesized in the presence of water-soluble polyvinyl alcohol (PVA) as a steric stabilizer, were deposited on solid substrates to yield homogeneous and porous membranes. The acid used to dope PANI, either hydrochloric acid or formic acid, has a marked influence on the size distribution of PANI and the morphology as well as the conductivity of the composite PANI-PVA membranes. The absorption spectra of the membranes obtained using formic acid during the synthesis were sensitive to pH changes which allowed to design a dual wavelength (603nm and 845nm) optical pH sensor. The membranes displayed a marked hysteresis during the pH 12 to pH 2 titration with respect to the titration performed from acid to basic solutions. The effect of this hysteresis could be suppressed by prolonged incubation in a solution at pH 2. The second acid to basic titration curve was then identical to the first one. In addition to the optical response of the composite, the PANI-PVA membranes displayed excellent time stability, allowing to use such membranes as stable and reusable pH meters not only in solution but also in moist gas phases. [Copyright &y& Elsevier]

Background: Health-care expenditures in the U.S. are continually rising, prompting providers, patients, and payers to search for solutions to reduce costs while maintaining quality. The present study seeks to define the out-of-pocket price that patients undergoing hand surgery are willing to pay, and also queries the potential cost-cutting measures that patients are most and least comfortable with. We hypothesized that respondents would be less accepting of higher out-of-pocket costs.Methods: A survey was developed and distributed to paid, anonymous respondents through Amazon Mechanical Turk. The survey introduced 3 procedures: carpal tunnel release, cubital tunnel release, and open reduction and internal fixation of a distal radial fracture. Respondents were randomized to 1 of 5 out-of-pocket price options for each procedure and asked if they would pay that price. Respondents were then presented with various cost-saving methods and asked to select the options that made them most uncomfortable, even if those would save them out-of-pocket costs.Results: There were 1,408 respondents with a mean age of 37 years (range, 18 to 74 years). Nearly 80% of respondents were willing to pay for all 3 of the procedures regardless of which price they were presented. Carpal tunnel release was the most price-sensitive, with rejection rates of 17% at the highest price ($3,000) and 6% at the lowest ($250). Open reduction and internal fixation was the least price-sensitive, with rejection rates of 11% and 6% at the highest and lowest price, respectively. The use of older-generation implants was the least acceptable cost-cutting measure, at 50% of respondents.Conclusions: The present study showed that most patients are willing to pay a considerable amount of money out of pocket for hand surgery after the condition, treatment, and outcomes are explained to them. Furthermore, respondents are hesitant to sacrifice advanced technology despite increased costs. [ABSTRACT FROM AUTHOR]

Collision-induced dissociation of doubly charged poly(dimethylsiloxane) (PDMS) molecules was investigated to provide experimental evidence for fragmentation reactions proposed to occur upon activation of singly charged oligomers. This study focuses on two PDMS species holding trimethylsilyl or methoxy end-groups and cationized with ammonium. In both cases, introduction of the additional charge did not induce significant differences in dissociation behavior, and the use of doubly charged precursors enabled the occurrence of charge-separation reactions, allowing molecules always eliminated as neutrals upon activation of singly charged oligomers to be detected as cationized species. In the case of trimethylsilyl-terminated oligomers, random location of the adducted charge combined with rapid consecutive reactions proposed to occur from singly charged precursors could be validated based on MS/MS data of doubly charged oligomers. In the case of methoxy-terminated PDMS, favored interaction of the adducted ammonium with both end-groups, proposed to rationalize the dissociation behavior of singly charged molecules, was also supported by MS/MS data obtained for molecules adducted with two ammonium cations. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: Polymer materials degradation is a well-known limitation to their characterization in SEM. In this paper authors present an additional possibility for polymer imaging offered by the Environmental SEM applied to the PMMA with micrometric relief. As shown by the so-called double-scan procedure, increasing the pressure enables to delay the degradation of the polymer surface. To evaluate quantitatively this observation, the classical formula to calculate the electron dose is adapted to ESEM characteristic. It is shown first that pressure enables to decrease the electron dose and all that takes place as if the skirt electrons do not participate in the irradiation. Secondly this procedure allows to obtain the critical dose of topographic degradation, applied to the PMMA with micrometric relief D C was found to be 1.31±0.28Cm−2. Finally it becomes then possible, knowing the D C for a given sample, to evaluate the limit of investigation without topographic surface degradation: for example, the maximal field of view (linked to the magnification) depending on the other parameters. [Copyright &y& Elsevier]

Carbon materials suffer from corrosion at the cathode of polymer electrolyte membrane fuel cells (PEMFCs). In the presence of water, carbon support materials are oxidized to carbon dioxide even at low potentials. Hence, nowadays it is very fashionable to look for alternative support materials, like oxides or conductive polymers. To gain the maximum performance for a new material one should also consider an appropriate electrode structure. This study shows the results for the incorporation of nanosized alternative support materials into advanced electrode architectures. Commercially available indium tin oxide (ITO) nanoparticles (<50 nm) are used as support for Pt nanoparticles in combination with Nafion-coated multi-walled carbon nanotubes (MWCNTs) on the cathode side of a PEMFC. The MWCNTs promote a high electronic conductivity and help to form a porous network, which could accommodate the Pt/ITO nanoparticles. The microscopic investigations show a homogeneous electrode structure composed of Pt/ITO and MWCNT/Nafion multilayer. Single cell measurements show a maximum power density of 73 mW cm−2 and a Pt utilization of 1468 mW mgPt−1 for the cathode. The performance data and the Pt utilization are comparable to a standard Pt/carbon black electrode possessing the same Pt loading in the electrode. Beside this, it is shown for the first time that ITO serves as support material under real fuel cell conditions. [ABSTRACT FROM AUTHOR]

This article, a follow-up on a recent review co-authored by one of us ( Prog. Polym. Sci. 2010, 35, 959-1021) discusses the most recent discoveries in the field of metal-catalyzed, reversible-deactivation radical polymerization. Remarkable examples include the use of non-toxic polyethylene glycols simultaneously as solvents and ligands for the iron-catalyzed ATRP, nickel complexes that promote polymerization via a dual radical/migratory-insertion pathway, and metalloenzymes as mediators of ARGET ATRP-type reactions. A thorough and critical overview of the mechanistic details as well as the experimental conditions used to carry out the polymerizations are given together with an overview of the future challenges. [ABSTRACT FROM AUTHOR]

The modification of solid-liquid interfaces with polyelectrolyte multilayer films appears as a versatile tool to confer new functionalities to surfaces in environmentally friendly conditions. Indeed such films are deposited by alternate dipping of the substrates in aqueous solutions containing the interacting species or spraying these solutions on the surface of the substrate. Spin coating is more and more used to produce similar films. The aim of this short review article is to provide an unifying picture about the deposition mechanisms of polyelectrolyte multilayer films. Often those films are described as growing either in a linear or in a supralinear growth regime with the number of deposited "layer pairs". The growth regime of PEM films can be controlled by operational parameters like the temperature or the ionic strength of the used solutions. The control over the growth regime of the films as a function of the number of deposition steps allows to control their functional properties: either hard and impermeable films in the case of linear growth or soft and permeable films in the case of supralinear growth. Such different properties can be obtained with a given combination of interacting species by changing the operational parameters during the film deposition. [ABSTRACT FROM AUTHOR]

Background: Crosslinked UHMWPE as a bearing surface in total joint arthroplasty has higher wear resistance than conventional UHMWPE but lower strength and toughness. To produce crosslinked UHMWPE with improved mechanical properties, the material can be treated before crosslinking by tension to induce molecular alignment (texture). Questions/purposes: We asked how (1) the microstructure of UHMWPE evolves when subjected to tension and (2) whether the new microstructure (texture) increases strength and toughness. Methods: We analyzed microstructure evolution of UHMWPE by small- and wide-angle xray scattering and scanning electron microscopy. We then developed a method to characterize the local strength and toughness of undeformed and textured UHMWPEs by means of nanoscratch tests along and perpendicular to the specimen axis. In three samples we determined the scratch characteristics in terms of deformation mode, coefficient of friction (μ), and viscoelastic recovery (r). Results: Before the tensile process, the scratch behavior of UHMWPE was characterized by a μ ranging from 0.64 to 0.68, no cracking, and r ranging from 0.58 to 0.60. Microfibrillar morphologic features resulted from the tensile process. The new microstructure had an increased strength (r = 0.78) and decreased toughness (cracking + μ = 0.77) perpendicular to the fibril axis and decreased strength (r = 0.53) and increased toughness (no cracking + μ = 0.55) parallel to the fibril axis. Conclusions: Textured UHMWPE behaves like a fiber composite with high strength and toughness in well-defined directions. However, the effect of crosslinking on these specific properties is unknown and therefore it is important to verify that the properties are retained. If wear resistance of crosslinked-textured UHMWPE is at least as high as that of crosslinked UHMWPE, novel medical devices made of crosslinked-textured UHMWPE could be developed and clinically tested. [ABSTRACT FROM AUTHOR]

In order to improve poly(vinyl chloride) (PVC) thermal stability, poly(vinyl butyral) (PVB) matrix and calcium carbonate nanoparticles were incorporated in plasticized PVC. Thermal properties of these composites were investigated by thermogravimetry analysis coupled with mass spectrometry and Fourier transform infrared spectroscopy (FTIR). This approach highlighted the efficiency of both PVB and CaCO3 as HCl scavengers by postponing both the onset degradation temperature and the HCl release. Moreover, a synergetic effect was evidenced regarding the HCl release. Finally, kinetic parameters of the PVC first degradation stage, determined using the Flynn–Wall–Ozawa’s method, revealed a significant increase of the activation energy by incorporation of CaCO3 in the presence or not of PVB. [ABSTRACT FROM AUTHOR]

Introduction: Opioid sparing protocols should be formulated with appropriate demand. Specific fracture location has been hypothesized as an important predictor of post-operative pain. The purpose of this study is to evaluate the impact of fracture location on perioperative opioid demand after surgery with the hypothesis that this factor would be significantly associated with perioperative opioid demand in upper extremity fracture surgery.Methods: A national database was used to identify1-month pre-operative to 1-year postdischarge opioid demand in oxycodone 5-mg equivalents in 336,493 patients undergoing fracture fixation of the clavicle through distal radius between 2010 and 2020. Three timeframes were evaluated: 1-month pre-op to 90-days post-discharge, 3 months post-discharge to 1-year post-discharge, and 1-month pre-op to 1-year postdischarge. Multivariable main effects linear and logistic regression models were constructed to evaluate the changes in opioids filled, opioid prescriptions, and odds of two or more opioid prescriptions in these timeframes based on fracture location with adjustment for age, sex, obesity, pre-operative opioid usage, and polytrauma.Results: Compared to distal radius fracture fixation, fixation of elbow, distal humerus, humeral shaft, and proximal humerus fractures were associated with large, significant increases in 1-month pre-op to 1-year post-discharge opioid filling (33.5 - 63.4 additional oxycodone 5-mg equivalents, all p<0.05) and number of filled prescriptions (0.33 - 0.92 additional prescriptions, all p<0.05) compared to patients with other operatively treated upper extremity injuries.Discussion: Fracture location was a significant predictor of perioperative opioid demand. Elbow, distal humerus, humeral shaft, and proximal humerus fracture fixation was associated with the largest increases in opioid demand after upper extremity fracture fixation. Patients with these injuries may be at highest risk of extensive opioid consumption.Level Of Evidence: Level III, retrospective, observational cohort study. [ABSTRACT FROM AUTHOR]

Introduction: Heterotopic ossification (HO) is a well-known sequela after an elbow injury and is widely studied given the associated morbidity. The anatomic location of HO development for specific elbow injuries has not been reported. The purpose of this study was to describe the precise, anatomic location of HO development after different peri-articular elbow injuries. Methods: A retrospective chart review was performed for patients with peri-articular elbow fracture and/or dislocation who underwent an elbow contracture release. The injuries were grouped into coronal shear distal humerus/AO 13.B3 (CSDH), distal humerus/AO 13.A, 13.B1, B2 or 13.C (DH), olecranon/AO 21.B1 (OL), radial head/AO 21.B2 (RH), extra-articular proximal radius and ulna/AO 21.A (EAPRU) fractures and elbow dislocations (DL). The HO location was determined by reviewing elbow radiographs and CT scans and were classified as anterior capsule, medial or lateral collateral ligaments, and posterior capsule/triceps insertion. Results: The study consisted of 49 patients, such as 6 CSDH, 13 DH, 6 OL, 21 RH, 4 EAPRU fractures and 20 elbow DL. All CSDH and RH fractures and 19/20 elbow DL developed HO in the collateral ligaments, while 12/13 DH fractures developed an anterior capsule HO. All 6 OL fractures developed HO posteriorly, and 3/4 EAPRU fractures developed a proximal radioulnar synostosis. Conclusions: Our findings suggest that the location of HO development is specific to the injury type and is influenced by the soft tissues involved. This is consistent with the understanding that HO is the abnormal ossification of normal structures. [ABSTRACT FROM AUTHOR]

Self‐healing polymer coatings have gained increased attention as a pathway for regenerating the inherent properties of surface following mechanical, physical or chemical damages. In most cases, the adhesion between the polymer coating layer and the substrate is driven by physical interactions. For some applications, immersing the polymer coating under water or exposing the coating to organic solvent vapors will undoubtedly lead to the coating delamination. One way to circumvent this issue is to attach the coating to the substrate via covalent bonds. However, this process will impede the self‐healing feature of the polymer coating due to the confinement of the volume change of the polymer to one dimension. Herein, surface‐attached metallo‐supramolecular polymer conetwork coatings are reported. The ability of the polymer conetworks to swell in organic solvent while maintaining their dimensional stability combined with reversible supramolecular cross‐links based on metal complexes enables the design of scratch‐healing polymer coatings. These metallo‐supramolecular polymer conetworks are prepared in a three‐step UV‐initiated polymerization reaction starting from the poly(pentafluorophenyl acrylate)‐l‐polydimethylsiloxane (PPFPA‐l‐PDMS)‐activated ester covalently attached to the substrate. Reacting the polymer conetwork coating with the 4‐(2‐aminoethyl)pyridine and cross‐linking the pyridine phases with ZnCl2 lead to the poly(N‐(2(pyridin‐4‐yl)ethyl)acrylamide‐Zn(II))‐l‐polydimethylsiloxane (PNP4EA‐Zn(II)‐l‐PDMS) polymer conetwork coatings with scratch‐healing ability. [ABSTRACT FROM AUTHOR]

• Thermal conductivity increases with GNP aspect ratio until a saturation value. • A reverse trend is observed between thermal conductivity and dispersion state. • Micro-tomography revealed micro-voids encapsulation caused by large aggregates. • Fillers aggregation, without voids, is best for thermal conductivity enhancement. An innovative combination of micro-computed X-ray tomography (μCT) and electron microscopy (SEM) coupled to an image-processing software was used to study the thermal conductivity of graphene nanoplatelets(GNP)/epoxy composites. This approach afforded a precise and systematic analysis of the dispersion state of the fillers in the epoxy matrix. Here, the influence of GNP aspect ratio on thermal conductivity enhancement (TCE) and the relationship between dispersion state of the fillers and TCE is revealed. The aggregation level of GNP was finely tuned by varying the sonication power. An unexpected trend towards enhanced thermal conductivity upon aggregation of the fillers is demonstrated. Moreover, μCT analysis revealed the encapsulation of micro-voids, undetectable with conventional methods, by large fillers aggregates. This study demonstrates that aggregation of the fillers increases the thermal conductivity of epoxy composites as long as it does not lead to voids encapsulation. [ABSTRACT FROM AUTHOR]

Background: A dorsal wrist-spanning plate (DWSP) can be affixed to the second or third metacarpal, depending on the morphology of the distal radial fracture (DRF) and on surgeon preference, but comparative biomechanical analyses between these methods are limited. This biomechanical study compared fixation to the second metacarpal versus the third metacarpal as measured by lunate facet fragment displacement in a cadaveric model of an axially loaded intra-articular DRF. The construct rigidity with the addition of an intrafragmentary lunate facet locking screw was also evaluated.Methods: A sample size of 14 cadaveric matched pairs was calculated to achieve 81.7% power. The 28 limbs were randomized to DWSP fixation to the second metacarpal (Group 1) or third metacarpal (Group 2); each wrist underwent an osteotomy simulating an unstable intra-articular DRF. Limbs were tested at axial loads of 50, 100, 150, 200, 250, and 300 N. Lunate facet displacement from the metaphyseal fragment at each load was measured with use of differential variable reluctance transducers. After initial testing, a locking screw was placed through the plate into the lunate facet fragment in the third metacarpal group (Group 3). Displacement measurements were repeated for all loads. Paired 2-tailed t tests with Bonferroni correction (significance, p < 0.008) were performed to assess differences in fragment stability between groups.Results: The average fracture displacement at 300 N was 0.8 mm in Group 1, 0.4 mm in Group 2, and 0.2 mm in Group 3. Plating to the third metacarpal more effectively resisted displacement compared with the second metacarpal at all axial loads (p < 0.008). The addition of a lunate facet screw further stiffened the construct at loads of ≥200 N (p < 0.008).Conclusions: Plate fixation to the third metacarpal with an intrafragmentary screw was the most biomechanically favorable construct, although other factors may favor an alternative distal fixation site. Mean displacement of the lunate facet fragment at 300 N was <1 mm in all groups.Clinical Relevance: The present study demonstrated that a DWSP affixed to the third metacarpal with an intrafragmentary screw provides the most effective stabilization of the lunate facet fragment in intra-articular DRFs. This study validates the use of intrafragmentary screws to increase stability in DWSP fixation. [ABSTRACT FROM AUTHOR]

The current challenge in self‐healing materials resides in the design of materials which exhibit improved mechanical properties and self‐healing ability. The design of phase‐separated nanostructures combining hard and soft phases represents an attractive approach to overcome this limitation. Amphiphilic polymer conetworks are nanostructured materials with robust mechanical properties, which can be tailored by tuning the polymer composition and chemical functionality. This article highlights the design of phase‐separated nanostructured polymers from metallo‐supramolecular amphiphilic polymer conetworks, and their application for self‐healing surfaces. The synthesis of poly(N‐(pyridin‐4‐yl)acrylamide)‐l‐polydimethylsiloxane polymer conetworks from the poly(pentafluorophenyl acrylate)‐l‐polydimethylsiloxane activated ester is presented. Loading of ZnCl2 salt into the phase‐separated polymer conetwork strengthens the network by cross‐linking the poly(N‐(pyridin‐4‐yl)acrylamide) phases, while offering reversible interactions needed for self‐healing ability. [ABSTRACT FROM AUTHOR]

During the first stages of Atomic Layer Deposition (ALD) of Al 2 O 3 on silicon (Si), the substrate nature affects the surface chemistry, leading to an initial island growth mode. Furthermore, an interfacial zone develops between the Si surface and the dielectric, thus damaging the physical properties of the deposited structure. In this work, these two main shortcomings are investigated for the ALD of Al 2 O 3 films on Si from TMA and H 2 O. The film and the interfacial zone are characterized by a complete range of techniques, including XRR, TEM, XPS, EDX and ToF-SIMS. In parallel, a computational model is developed to study the initial nucleation and growth steps of the film. An induction period is experimentally evidenced and numerically reproduced, together with the island growth and coalescence phenomena. The chemical composition of the (Al, O, Si) interfacial layer is precisely analyzed to get insight in the mechanisms of its formation. We show that Si oxidation occurs during the island growth, catalyzed by the presence of Al, while it is also fed by species interdiffusion through the ALD film. Unlabelled Image • The initial steps of Al 2 O 3 ALD on Si are studied, experimentally and theoretically. • An induction period is evidenced leading to island growth. • An interface oxide layer is formed between the Al 2 O 3 film and the Si substrate. • The interface consists of SiO x , with possible presence of SiOAl. • The interface is formed during the island growth and through species interdiffusion. [ABSTRACT FROM AUTHOR]

Abstract The deposition of thin coatings by plasma processes operated at atmospheric pressure is a versatile process for the deposition of functional coatings. However, there is a need to understand their mechanical properties as a function of plasma deposition process parameters since the durability of the coatings is strongly dependent on these properties. In this work, a new approach to obtaining plasma coatings with a controlled level of cross-linking was developed. The precursor molecule to plasma polymer coatings is hexanediol dimethacrylate (HdiMA), a di-functional methacrylate; the plasma deposition conditions were chosen to strongly decrease the precursor fragmentation, so that the plasma polymerization of this precursor leads to a cross-linked structure through the reaction of methacrylate bonds. Plasma coatings from HdiMA are deposited in different plasma conditions. The chemical structure of plasma polymers is investigated by means of infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The mechanical properties of the coatings are determined by nanoscratch and atomic force microscopy (AFM) force curves tests. Better mechanical properties are obtained for coatings deposited with a low concentration of aerosol in the plasma and a higher plasma power. This corresponds to coatings exhibiting the higher conversion rate. Graphical abstract Unlabelled Image Highlights • Thin plasma polymer coatings are deposited from hexanediol dimethacrylate • Deposition is performed in a DBD plasma at atmospheric pressure • Plasma deposition conditions are changed to modify the coating structure • The low precursor fragmentation and the plasma polymer cross-linking are evaluated • Better mechanical properties are obtained when the aerosol concentration is lows [ABSTRACT FROM AUTHOR]

The mechanics of structure genome has been extended to heat conduction problem of composite materials with a general linear thermal imperfect interface model. This full field micromechanics approach is applied to predict the effective thermal conductivity of composite materials containing thermal imperfect contact between the matrix and the reinforcements. Examples of spheroidal particles reinforced composites are used to demonstrate the robustness and accuracy of this micromechanics theory. The size-dependency of the overall thermal conductivity shows the importance of imperfect interfaces in modeling the thermal behavior of composite materials. The proposed micromechanics method is versatile and can be applied for estimating the effective thermal conductivity of nanocomposite materials. [ABSTRACT FROM AUTHOR]

A personal narrative is presented which explores the author's experience of performing an allograft anterior cruciate ligament (ACL) reconstruction as an orthopaedic surgeon.

During the past decade, synthesizing silver nanoparticles (Ag NPs) by liquid phase-pulsed laser ablation (LP-PLA) has attracted a lot of attention. Basically, this technique allows producing various metallic nanoparticles with controlled size, shape, composition, or surroundings in several liquids (i.e., water, ethanol, acetone, toluene, and so forth). Recently, such processes have been studied in liquid organic monomer such as methyl methacrylate (MMA). However, the influence of the laser parameters on the materials synthesized in such reactive liquid and their features were not fully investigated so far. Here we investigate the LP-PLA of silver in two different but rather similar acrylate monomers: dodecyl acrylate (DOCA) and 1H,1H,2H,2H perfluorodecyl acrylate (PFDA). The influence of the fluence and the number of pulses on the production, size, and morphology of the materials has been examined. First, factorial design experiments have been achieved in order to determine the weight of the laser parameters in each precursor. This study shows two highly different behaviors in function of the monomer where the process took place. This has been explained by the plasma plume confinement and/or the "interpulses" self-absorption of the particles by the laser beam. The formation of graphite around the synthesized AgNPs has been highlighted by Raman spectroscopy at low number of pulses. Nevertheless, increasing the number of pulses could lead to three phenomenon depending on the fluence and the used monomer: degradation of the matrix, conservation of the matrix with changes in AgNPs size and distribution, or sustainment of the matrix with any changes in the particles properties. So the surrounding, the size, and stability could be triggered by adjusting these parameters. This paper does highlight that LP-PLA is a powerful technique to provide AgNPs in acrylate monomer with a good control of their features. [ABSTRACT FROM AUTHOR]

Background: Quality measures are now commonplace and are increasingly tied to financial incentives. We reviewed the existing quality measures that address the upper limb and tested the null hypothesis that structure (capacity to deliver care), process (appropriate care), and outcome (the result of care) measures are equally represented.Methods: We systematically reviewed MEDLINE/PubMed, Embase, Google Scholar, the American Academy of Orthopaedic Surgeons Clinical Practice Guidelines, the National Quality Forum, the Agency for Healthcare Research and Quality, and the Physician Quality Reporting System for quality measures addressing upper limb surgery. Measures were characterized as structure, process, or outcome measures and were categorized according to their developer and their National Strategy for Quality Improvement in Health Care (National Quality Strategy) priority as articulated by the U.S. Department of Health & Human Services.Results: We identified 134 quality measures addressing the upper limb: 131 (98%) process and three (2%) outcome measures. The majority of the process measures address the National Quality Strategy priority of effective clinical care (90%), with the remainder addressing communication and care coordination (5%), person and caregiver-centered experience and outcomes (4%), and community/population health (1%).Conclusions: Our review identified opportunities to develop more measures in the structure and outcome domains as well as measures addressing patient and family engagement, public health, safety, care coordination, and efficient use of resources. The most common existing measures-process measures addressing care-might not be the best measures of upper limb surgery quality given the relative lack of evidence for their use in care improvement. [ABSTRACT FROM AUTHOR]

Protective coatings from diethylphosphatoethyltriethoxysilane (DEPETS) have been deposited on different polymer substrates in a plasma discharge operated at atmospheric pressure. Plasma polymer chemistry and structure were characterized by means of Fourier transform infrared spectroscopy (FTIR), laser desorption ionization-mass spectrometry (LDI-MS), nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). A chemical structure of the plasma polymer has been proposed based on the coating molecular characterization. Coatings were deposited on polycarbonate (PC) and polyamide 6 (PA6) substrates. The flame retardant properties of coated substrate samples were assessed using cone calorimetry and compared to those of bare substrates. A significant increase in the time to ignition (TTI), up to +143%, was recorded after coating deposition due to the formation of a high-performance barrier layer at the surface of both polymer substrates. [ABSTRACT FROM AUTHOR]

Biocompatible plasma polymers are expected to be used in various applications in medicine such as drug delivery with a controlled release. In this context we investigated the possibility to monitor the kinetic of hydrolytic degradation of plasma polymers by tailoring the chemistry of the precursor. A homemade precursor way synthesized by grafting acrylate function on both side of a polycaprolactone diol (PCL diol) to produce a PCL diacrylate characterized by IR, NMR, and MS to confirm its chemical structure. Acrylates constitute a promising class of precursors to improve the retention of the integrity of the precursor by working in soft plasma conditions. The plasma polymerization of the so-synthesized precursor have been highlighted by means of a multi technique analytical strategy and ensured the retention of hydrolyzable ester function of the precursor. Finally the thickness consumption during immersion in PBS were performed and found to be slower as compared to the degradation kinetic of a plasma polymerized methacrylic anhydride. [ABSTRACT FROM AUTHOR]

New intumescent flame retardant coating made from poly(allylamine) (PAH), sodium polyphosphates (PSP) and TiO 2 nanoparticles was designed using layer-by-layer assembly. The (PAH-PSP-PAH-TiO 2 ) n (where “ n ” denotes the number of quadralayers) assembly has been deposited on silicon wafers in order to evaluate its thickness as well as its topography by ellipsometry and by atomic force microscopy (AFM), respectively. According to AFM measurements, the coating appears smooth and continuous. The film exhibits a linear growth regime with a thickness of approximately 500 nm for 15 quadralayers (QL). However, when deposited on polyamide or polyester fabrics, this coating displays different morphologies as it was shown by scanning electron microscopy (SEM) analysis. The thermo-oxidative degradation and flammability properties of the coatings and their effect on polyamide and polyester fabrics have been evaluated by thermogravimetric analyses (TGA) and pyrolysis combustion flow calorimeter (PCFC) respectively. We have found that the coating acts efficiently in reducing the peak of the heat release rate (pHRR) value for polyamide fabric while very limited effect was observed on polyester fabric. [ABSTRACT FROM AUTHOR]

Novel ultra-high molecular weight polyethylene (UHMWPE) composites were processed by micro-extrusion with polyaniline (PANI) as potential reinforcing and radical scavenging agent and with lauryl gallate (LG) as coupling agent. By means of UV–vis spectroscopy, it was found that the presence of PANI reduced at maximum by 27.3% the concentration in free radicals of a 2,2-dimethyl-1-picrylhydrazyl (DPPH) solution in which was immersed the composite. This result was obtained with the UHMWPE/LG/PANI weight composition 89/1/10, which also demonstrated to retain the viscoelastic and tensile properties of neat UHMWPE. The dispersion of PANI micro-particles within the UHMWPE matrix may be an alternative to the stabilization step of crosslinked UHMWPE used in joint prosthesis. [ABSTRACT FROM AUTHOR]

The use of reliable reference compounds was recently shown as a powerful strategy for a thorough characterization of plasma-polymers, but their elaboration remains a topical issue since wet chemistry leads to linear structures with specific chain ends which poorly mimic the notorious disorder found in plasma-polymers. Here is proposed the elaboration of standards directly using aerosol assisted plasma polymerization. Exaggerating the phenomenon observed in a so-called ante plasma zone where no discharge is ignited but thick organic coatings are deposited brought the concept of discharge overfeeding to decrease the energy per particle and produce intermediate polymeric materials between conventional polymers and plasma-polymers, synthesized through a plasma-assisted free radical polymerization. [ABSTRACT FROM AUTHOR]

Cardanol and cardanol derivatives are among the most important biobased materials currently investigated in green chemistry, as renewable and promising building blocks in lieu of traditional raw materials from non renewable resources, in particular owing to the olefinic linkages on the C15 alkyl side-chain. Despite the increasing interest they arouse, analytical chemistry dedicated to cardanol and associated resins has been rarely reported in the literature, found even poorer when dealing with chromatography and mass spectrometry. In this work, a thorough molecular characterization was conducted using matrix assisted laser desorption ionization (MALDI) mass spectrometry, size exclusion chromatography (SEC), and SEC–MALDI coupling to gain insights into the composition of phenolated, epoxidized, and epoxidized phenolated cardanol. A nomenclature was proposed to properly describe the numerous species found in these materials, while simulations of the unsaturation patterns and their comparison with the detected patterns in MALDI-MS gave useful details about the phenolation treatment expected to occur on the polyunsaturated C15 side chain. Finally, the SEC–MALDI off-line coupling allowed SEC peaks to be deconvoluted by mass spectrometry and MALDI artefacts related to matrix adduction to be pointed out. [ABSTRACT FROM AUTHOR]