Search

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]

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]

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]

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."

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]

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]

It is well established that the chemical structure of surfactants used to promote the dispersion of clay minerals in polymers plays a major role in clay polymer nanocomposites preparation. However, much less explored is the incorporation of reactive surfactants capable of covalently grafting to monomers and polymer chains. In this work, the effect of the reactivity degree of bio-based surfactants onto the exfoliation of montmorillonite in epoxy is evidenced. For this purpose, 3 surfactants were prepared from a derivative of Cardanol, incorporating reactive groups: N(CH 3 ) 2 , NH 2 or two NH 2 functions. In each case, the organomodification of the clay mineral results in a similar interlayer space increase. Combined chemical derivatization and MALDI-TOF/MS was used to evidence the differences of the residual reactivity of the intercalated surfactants. Finally each organomodified clay mineral was used for the preparation of epoxy nanocomposites. Interestingly, for the most reactive surfactant, X-ray diffraction analysis evidenced a fully exfoliated structure while semi-exfoliation or intercalated structure was found for the less reactive surfactants. [ABSTRACT FROM AUTHOR]

Abstract: A polymeric bilayer composed of two poly(styrene) layers differing by their molecular weights (MW) was elaborated to mimic a MW gradient and analyzed by a combination of TOF-SIMS, MALDI-MS and Nanoscratch (NS). A direct TOF-SIMS profiling conducted using a Cs+ ion beam lead to the detection of fragments from carbonated layers without any data about their MW, making the fine bilayer architecture indistinguishable. Spots of various depths were hence created using the same Cs+ ion bombardment for different sputtering times, and further mass-analyzed by the recently developed Surface-Layer MALDI-MS technique, to evaluate the MW of the very top polymeric layer of each crater. The off-line combination of ion etching and LASER analysis allowed a molecular weight depth profile to be plotted, as a function of the physical depth measured by NS in each crater (instead of the usual sputter time). This original coupling is expected to provide useful molecular and/or molecular weight data about complex organic and/or polymeric multi-layers or gradients. [Copyright &y& Elsevier]

Abstract: In this work, an intumescent coating of (polyallylamine-polyphosphate)n (“n“ denotes the number of bilayers (BL) deposited) was elaborated through Layer-by-Layer assembly in order to improve the fire performance of polyamide 6.6 fabrics (PA). The thickness of this intumescent assembly increases linearly as a function of the number of bilayers deposited. Thermogravimetric analysis results indicate that the presence of such assembly catalyzes and changes the degradation pathway of virgin polyamide fabrics. The fire performance was evaluated by Pyrolysis Combustion Flow Calorimeter. The fire results show on the one hand a significant decrease of peak of heat release rate (pHRR) and on the other hand a shift to lower temperatures (assigned to a catalytic effect) as a function of the number of bilayers deposited. A maximum decrease of pHRR (−36%) is obtained for the 40 BL coated fabric in comparison with uncoated polyamide fabric. [Copyright &y& Elsevier]

In this paper, we focused our attention on the elaboration of a hydrolyzable plasma-polymer produced by aerosol-assisted atmospheric pressure plasma process. A dielectric barrier discharge (DBD) was hence fed with a commercial methacrylic anhydride precursor - bearing an anhydride hydrolyzable function and two methacrylates groups aiming at producing a highly cross-linked deposit - to produce thin coatings of plasma-polymerized (pp) methacrylic anhydride. IR and NMR were performed to highlight the retention of the hydrolyzable group. After immersion in water, mass spectrometry analysis was conducted on the aqueous medium to characterize the end-products and consequently confirm the occurrence of a hydrolytic degradation. A huge 80% thickness decrease was finally pointed out by nanoscratch measurements after 10 days. [ABSTRACT FROM AUTHOR]

Background: Surgical treatment for terrible triad injuries of the elbow (defined as elbow dislocations with concomitant fractures of the radial head and coronoid) remains a challenging clinical problem. Specifically, the question of whether to repair or replace the radial head remains controversial. Questions/purposes: We compared patients with terrible triad injuries of the elbow whose radial head fracture was treated with either internal fixation and internal fixation (ORIF) or radial head arthroplasty in terms of (1) clinical outcome measures (DASH and Broberg-Morrey scores, ROM), (2) elbow stability and radiographic signs of arthrosis, and (3) complications and reoperation rates. Methods: Retrospective review identified 39 patients with terrible triad injuries and minimum 18-month complete clinical and radiographic followup (mean, 24 months; range, 18-53 months). Patients were managed with a standard algorithm consisting of (1) repair (n = 9) or replacement (n = 30) of the radial head, (2) repair of the lateral ulnar collateral ligament, and (3) repair of the coronoid fracture. During the study period, the radial head generally was internally fixed when there were fewer than four articular fragments; otherwise, it was replaced. Evaluation included the DASH score, the Broberg-Morrey index, measurements of elbow stability and motion, and radiographic assessment for signs of arthrosis; chart review was performed for complications and reoperations. Complete followup was available on 87% (39 of 45 patients). Results: There were no differences between groups in terms of ROM or elbow scores. All patients who underwent radial head arthroplasty at the index procedure had a stable elbow at final followup whereas three of nine patients who underwent ORIF were unstable (p = 0.009). However, 11 patients who underwent arthroplasty demonstrated radiographic signs of arthrosis compared to none in the ORIF group (p = 0.04). Eleven patients (28%) underwent reoperation (seven arthroplasty, four ORIF) for various reasons. With the numbers available, there was no difference in reoperation rate between groups (p = 0.45). Conclusions: For terrible triad injuries, radial head arthroplasty afforded the ability to obtain elbow stability with comparable overall outcomes when compared to ORIF. As these injuries commonly occur in younger patients, longer-term studies will be required to ascertain whether the apparent benefits of radial head arthroplasty are offset by late complications of arthroplasty, such as loosening. Level of Evidence: Level III, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

In this work, the use of Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) was explored as a technique for monitoring the interfacial retro Diels–Alder (retro DA) reaction occurring on well-controlled self-assembled monolayers (SAMs). A molecule containing a Diels–Alder (DA) adduct was grafted on to the monolayers, then the surface was heated at different temperatures to follow the reaction conversion. A TOF-SIMS analysis of the surface allowed the detection of a fragment from the molecule, which is released from the surface when retro DA reaction occurs. Hence, by monitoring the decay of this fragment's peak integral, the reaction conversion could be determined in function of the time and for different temperatures. The viability of this method was then discussed in comparison with the results obtained by 1H NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Silver is a usual antibacterial agent acting in water solutions. However, quantitative data fail to anticipate the silver availability for interactions with bacterial cells and the resulting fluctuations of the inhibitory and bactericidal concentrations according to the silver amount and chemical composition of the liquid environment. We investigated whether and how three different biological media modify silver ions (Ag+) and nanoparticles (AgNPs) and alter their antibacterial performances against Escherichia coli K12. The predominant silver species highly differed in terms of nature and quantity according to the medium. Bioavailability was reduced to a few percent of the initial Ag+ amount in physiological serum (NaCl) and lysogeny broth (LB), while it was higher than 67% in minimal phosphate medium (M63G). To reach similar antibacterial performances, Ag+ concentrations were 100 times lower in M63G than in the other media. Even with a silver concentration of 10−1 M, 53% of the bacterial cells living after 3 h in LB were undamaged and revealed normal metabolic activity, while the cells were almost completely eliminated in M63G. Effects of AgNPs were also strongly but differently modulated by the medium's components. AgNPs revealed higher antibacterial effect than Ag+ in NaCl and M63G with similar silver content, thus providing an argument to assert that AgNPs act through a combination of the release of Ag+ and intake of AgNPs. Our results finally provide guidelines about the Ag+ dose that must be released from coatings to reach efficient performances according to the surrounding medium and the framework of the study. [ABSTRACT FROM AUTHOR]

Coatings have been deposited from acrylates and methacrylates mixtures by means of an aerosol assisted atmospheric plasma process. The reference coating precursor is dodecyl acrylate (DOCA). In order to improve the coatings mechanical properties, one diacrylate and one dimethacrylate are added to DOCA in the precursor mixture. It is expected that they act as cross‐linking agents, thus modifying the coatings macromolecular structure and improving the coating mechanical properties. The influence of cross‐linkers concentration on the coatings properties is investigated. An improvement of coatings scratch resistance when the concentration of cross‐linkers increases in the mixture is observed, but the effect on coatings structure is different between the diacrylate and the dimethacrylate. This work introduces new insights in the frame of plasma coatings deposition by investigating the reinforcement of plasma polymers when cross‐linkers are added to the precursors mixture. An improvement of coatings scratch resistance when the concentration of cross‐linkers increases in the mixture is observed, but the effect on coatings structure is different between the two crosslinkers under study. [ABSTRACT FROM AUTHOR]

The plasma copolymerization of two acrylate precursors with different hydrophobic side chains, namely 1H,1H,2H,2H‐perfluorododecyl acrylate (PFDA) and dodecyl acrylate (DOCA), were deposited at atmospheric pressure. By adding different ratios of PFDA into the DOCA solution changes in the chemistry and microstructure were observed and examined using multiple techniques combining FTIR, XPS, SEM, and AFM. Increasing the content of PFDA led to an increase in the F/C ratio and the roughness of the deposits. Considering such variation when PFDA increases, different growth mechanisms are proposed. Finally, adjusting the monomer ratio demonstrates the feasibility of controlling the wettability of the coatings from hydrophobic to superhydrophobic. Control the surface wetting properties by plasma co‐polymerization of two acrylates. Superhydrophobicity is achieved by a low surface tension and a specific roughness. The present study aims to understand the change in wettability with the evolution of the monomer ratio. A multi‐scale and technique investigation has been performed and chemical and topographical changes have been highlighted. [ABSTRACT FROM AUTHOR]

Front Cover: A difunctional precursor bearing an anhydride hydrolyzable function and two methacrylates groups was plasma polymerized by aerosol assisted atmospheric dielectric barrier discharge to produce a highly cross‐linked water sensitive coating. First results confirmed the good retention of the hydrolysable function as well as the hydrolytic degradation, achieved in about ten days under normal conditions. Further details can be found in the article by Grégory Mertz et. al. on page 728. [ABSTRACT FROM AUTHOR]