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Introduced a experiment measuring method of polymer melt bulk modulus. This method based on the PVT reciprocity principle of polymer melt. Depending on liquid attribute of polymer melt, which means pressure changing caused micro variety of volume of certain quality melt in sealed container, polymer melt bulk modulus under the different temperature and pressure could be measured. According with the Polymer Free Volume Theory, the result proved the scientificity of this method.

A new and easy-to-prepare, surfactant-based polymer-free fluid, CTAB-SA, consists of etradecyl trimethyl ammonium bromide, cetyl trimethyl ammonium bromide and octadecyl trimethyl ammonium bromide with salicylic acid is described. The properties as a fracturing fluid were evaluated with regard to viscoelasticity and proppant carrying capability. The results showed that these water gels have strong proppant-carrying capacity and high viscoelasticity, and the best performance was obtained from the gels derived from octadecyl trimethyl ammonium bromide with salicylic acid. The viscoelasticity of these gels were increase with the quality ratio of ammonium bromide to acid.

Recently, polymer free fracturing fluid was investigated to reduce formation and fracture conductivity damage during and after hydraulic fracture treatment. This fluid system uses a viscoelastic surfactant (VES). Some shortcomings of VES fluid such as excessive leakoff and the limit of temperature range have limited the use of the conventional VES fluid. On the basis of the conventional VES fracturing fluid system, a new anionic VES fracturing fluid “D3F-AS05” was developed through an extensive experiments. The fluid utilizes a specially formulated anionic surfactant. Analysis of laboratory tests indicates that the new fluid has good viscosity stability with high ability of carrying sand; the fluid also has low fluid loss and low frictional resistance. On the other hand, more than 97% returned permeability was achieved, which indicates low formation damage after gel-breaking. The temperature stability of the new fluids extended to more than 90 °C. This allowed the fluid to be used in the deep well with a high injection rate. This paper provides the procedures and the chemical additive of the new fluid and has focused on the performance of the fluid under different concentrations. The paper also illustrates the effect of the fluid in fracture geometry with a field application result.

The increased risk of late ischemic events with drug eluting stents (DES) may, in part, be due to persistent inflammation and delayed vascular healing induced by their durable polymer (DP) coating. Biodegradable-polymer (BP-) and polymer-free (PF-) DES were developed in an attempt to mitigate this

Permanent-polymer everolimus-eluting stents (EES) have proven in several randomized trials and observational registries to provide satisfactory safety and effectiveness results in patients undergoing percutaneous coronary intervention. However, the permanence of synthetic polymer still poses a

Polymer-free drug-coated stents (PF DCS) avoid the concern for inflammatory material responses, but pose challenges in providing controlled drug release and sustained tissue retention. We used immunofluorescence (IF) methods to contrast the arterial distribution of Sirolimus and the highly

Despite all the benefits of drug-eluting stents (DES), concerns have been raised over their long-term safety, with particular reference to stent thrombosis. In an effort to address these concerns, newer stents have been developed that include: DES with biodegradable polymers, DES that are polymer free, stents with novel coatings, and completely biodegradable stents. Many of these stents are currently undergoing pre-clinical and clinical trials; however, early results seem promising. This paper reviews the current status of this new technology, together with other new coronary devices such as bifurcation stents and drug-eluting balloons, as efforts continue to design the ideal coronary stent.

The increased risk of late ischemic events with drug eluting stents (DES) may, in part, be due to persistent inflammation and delayed vascular healing induced by their durable polymer (DP) coating. Biodegradable-polymer (BP-) and polymer-free (PF-) DES were developed in an attempt to mitigate this

Polymer-free drug-eluting stents(PF-DES) were developed to mitigate the risk of late ischemic events observed with durable-polymer DES (DP-DES). However, trial results are inconsistent with longer-term safety and efficacy of PF-DES unknown. We performed a meta-analysis of randomized controlled

Stent-based delivery of tacrolimus has shown neointimal hyperplasia and restenosis reduction; FK506 is a water insoluble macrolide immunosuppressant. The purpose of this study was to evaluate acute and chronic tissue response to a polymer-free FK506 drug-eluting stent implantation in a porcine coronary artery model. Seventy-eight nonatherosclerotic minipigs underwent successful placement of 134 stents (control n = 56; FK506 (1.5 μg/mm2) n = 44; FK506 (2.6 μg/mm2) n = 34) at 7, 15, 30, 90, or 180 days. Endothelialisation was almost complete at 7 days, complete at 15 days. At 30 and 90 days, mean neointimal thickness, neointimal area, and % stenosis was significantly less for drug-eluting stents compared with controls. At 180 days, histomorphometric values were similar for eluting and control stents. The FK506-eluting stent allows for a complete re-endothelialisation at 15 days and favorably moderate neointimal hyperplasia at 30 and 90 days in the porcine coronary model. Because of a possible limited bioavailability of FK506, long-term inhibition of neointimal formation was not sustained at the considered follow-up. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009

PurposeThe purpose of this paper is to underline the future need for OEMs to receive lowSAP, polymer‐ and metal‐free engine oils with high‐viscosity indices and to illuminate for other OEMs the technical feasibility for application of alternative engine oils based on esters or blends of hydrocarbons with esters or polyglycols.Design/methodology/approachThe strategic goal depends technically on the use of intrinsic properties of alternative base fluids, thus substituing some additives, like anti‐wear, extreme pressure and viscosity index improvers. The prone wear resistance of novel triboactive/‐reactive materials enables higher portions of mixed/boundary lubrication generated by oils with a lower viscosity.FindingsOverall, the different bionotox and low‐ash prototype engine oils with reduced additive contents displayed isoperformance regarding the tribological behaviour against cast iron and triboreactive materials. APS‐Tin−2Cr2O2n−1 displayed an overall wear resistance comparable with grey cast iron with high‐carbon content and liner wear reduction of one order of magnitude when mated with Mo‐based rings. Both tests confirmed the potential for substituing molybdenum‐based rings by APS‐Tin−2Cr2O2n−1. The most significant reduction in “system wear” down to “zero wear” was demonstrated by mating the APS‐Tin−2Cr2O2n−1 coated piston rings with smooth machined HVOF‐(Ti,Mo)(C,N) liner coatings.Research limitations/implicationsAs lubricants are today not part of the core business of automotive OEMs, the next steps have to be proposed by the petrochemical suppliers. It is recalled here that some OEMs in their history developed and produced lubricants.Practical implicationsThe customer will appreciate any increase in longevity resulting in reduced maintenance. The OEM now owns, under increased solicitations, now a future‐oriented tool box in order to respond to environmental and CAFÉ demands with reasonable cost management.Originality/valueThis OEM report displays the complete methodology in order to adopt alternative engine oils in existing engine architectures.

In this paper we provide the first model of drug elution from polymer-free arterial drug-eluting stents. The generalised model is capable of predicting drug release from a number of polymer-free systems including those that exhibit nanoporous, nanotubular and smooth surfaces. We derive analytical solutions which allow us to easily determine the important parameters that control drug release. Drug release profiles are provided, and we offer design recommendations so that the release profile may be tailored to achieve the desired outcome. The models presented here are not specific to drug-eluting stents and may also be applied to other biomedical implants that use nanoporous surfaces to release a drug.

Background— The use of a stent to deliver a drug may reduce in-stent restenosis. Paclitaxel interrupts the smooth muscle cell cycle by stabilizing microtubules, thereby arresting mitosis. Methods and Results— On the basis of prior animal studies, the European evaLUation of the pacliTaxel Eluting Stent (ELUTES) pilot clinical trial (n=190) investigated the safety and efficacy of V-Flex Plus coronary stents (Cook Inc) coated with escalating doses of paclitaxel (0.2, 0.7, 1.4, and 2.7 μg/mm 2 stent surface area) applied directly to the abluminal surface of the stent in de novo lesions compared with bare stent alone. The primary efficacy end point was angiographic percent diameter stenosis at 6 months. At angiographic follow-up, percent diameter stenosis was 33.9±26.7% in controls (n=34) and 14.2±16.6% in the 2.7-μg/mm 2 group (n=31; P =0.006). Late loss decreased from 0.73±0.73 to 0.11±0.50 mm ( P =0.002). Binary restenosis (≥50% at follow-up) decreased from 20.6% to 3.2% ( P =0.056), with no significant benefit from intermediate paclitaxel doses. Freedom from major adverse cardiac events in the highest (effective) dose group was 92%, 89%, and 86% at 1, 6, and 12 months, respectively ( P =NS versus control). No late stent thromboses were seen in any treated group despite clopidogrel treatment for 3 months only. Conclusions— Paclitaxel applied directly to the abluminal surface of a bare metal coronary stent, at a dose density of 2.7 μg/mm 2 , reduced angiographic indicators of in-stent restenosis without short- or medium-term side effects.

Patients with acute coronary syndromes have an increased risk of stent thrombosis. A considerable proportion of these patients are also at increased risk of bleeding, representing a challenge to optimal selection of stent type and duration of dual antiplatelet therapy. Recent evidence supports polymer-free drug-eluting stents as a safe and effective option for this challenging subset of patients.

Many mechanical and rheological properties of polymers are related to the amount and the distribution of its free volume. In this work, the evolution of free volume and its distribution in a linear model polymer resembling polyethylene under extensional strain are studied using a combination of molecular dynamics (MD) and Voronoi tessellation. When the molecular orientation due to stretch increases, the total number of voids in the sample decreases along with the number-average void size, while the number of larger unoccupied regions in the polymer increases, which become more elongated due to stretch. The hand-sphere probe shows that the overall free volume is decreasing during stretching; however, the reduction is not distributed evenly in the region. Free volume associated with atoms located away from the ends of molecular chains decreases while the free volume associated with atoms located at the molecular ends increases with stretch. Results from this computational work are in good agreement with sev...

We prepared a new class of organic–inorganic hybrid materials with high refractive indices and thermoplasticity. Titanium and zirconium alkoxides were hydrolyzed in the presence of β-diketones of h...

The purpose of this all-comers registry was to assess the safety and efficacy of a polymer-free sirolimus coated, ultrathin strut drug eluting stent (PF-SES) with a focus on acute coronary syndrome (ACS). Elective coronary artery disease (CAD) patients on short (≤ 6 months) and long (> 6 months)

We sought to evaluate the angiographic efficacy and clinical safety and effectiveness of the combined sirolimus-eluting CD34 antibody coated Combo stent (OrbusNeich Medical, Ft. Lauderdale, Florida) in a randomized trial designed to enable its approval by the China Food and Drug Administration.

An operator and its partners operating in the Gulf of Guinea decided to drill and complete a horizontal open hole gravel pack well in deep water field to optimize production. Minimizing formation damage during the drilling and completion operation was a primaryconcern. In addition to preventing formation damage, the relative narrow pressure window, scaling tendency of formation water with divalent brines were concerns requiring the implementation of new fluid systems to mitigate the aforementioned issues. This required intensive laboratory design process and preplanning. Drilling and completion fluids were designed and customized based on results from tests previously mentioned. Compatibility between all fluids with formation water were assessed at 180, 225 and 250°F. Return permeability simulated drilling and completion sequences to prove non damaging properties. Logistic field challenges to handle systems were successfully managed in a remote location by sufficient pre-planning. Selected fluid systems were used in the field to successfully drill and complete the alpha beta open hole gravel pack well, with higher than expected production. Design process, results and field application parameters are discussed in this paper.

The introduction of intracoronary stents represented a major advance in interventional cardiology. While bare metal stents set the benchmark for improved safety over angioplasty, intimal hyperplasia and subsequent restenosis were important limitations. First-generation drug-eluting stents demonstrated significant improvements in efficacy, but not necessarily safety, and further technologic developments have focused on optimizing both. Current advances and understanding in stent design continue to improve on these concepts. This review summarizes past and present technology with particular emphasis on the principles underlying the efficacy and safety of drug-eluting stents, and offers a glimpse into the next generations of stents aimed at treating symptomatic coronary artery disease.

The tree initiation voltage of impregnated crosslinked polyethylene (XLPE) with a dielectric liquid is drastically improved compared to normal XLPE for both ac and impulse voltage application. It is considered that liquid fills the polymer free volume, and removes space for electrons to be accelerated to high energy. The experimental results support that collision impact of electrons accelerated in polymer free volume is the dominant cause of electrical tree initiation, and also show that liquid impregnation is a promising way to improve performance and prolong the life of polymeric insulating materials.

Summary Polymer residues that stay in the fracture after fracturing can limit the treatment effectiveness. A new and easy-to-prepare, surfactant-based polymer-free fluid, ClearFRAC™, that consists of a quaternary ammonium salt derived from a long-chain fatty acid is described. In brine, it builds fluid viscosity and viscoelasticity due to the formation of highly entangled worm-like micelles. The micelles have a gross structure similar to a polymer chain. Since the viscosity of the fluid depends on the nature of micelles, the fluid can be broken by changing this micellar structure. The breaking occurs when the fluid is exposed to hydrocarbons or diluted with formation water. Therefore, conventional breakers are not required, and the produced oil or gas can act as breakers for this fluid system. The structural characteristics of this viscoelastic surfactant-based fluid to its chemical and physical properties are correlated in this article. Structure, rheology, fluid loss, and conductivity of this surfactant fluid together with its case histories are presented.

This work introduces a polymer-free optode nanosensor for ratiometric sodium imaging. Transmembrane ion dynamics are often captured by electrophysiology and calcium imaging, but sodium dyes suffer from short excitation wavelengths and poor selectivity. Optodes, optical sensors composed of a polymer matrix with embedded sensing chemistry, have been translated into nanosensors that selectively image ion concentrations. Polymer-free nanosensors were fabricated by emulsification and were stable by diameter and sensitivity for at least one week. Ratiometric fluorescent measurements demonstrated that the nanosensors are selective for sodium over potassium by ~1.4 orders of magnitude, have a dynamic range centered at 20 mM, and are fully reversible. The ratiometric signal changes by 70% between 10 and 100 mM sodium, showing that they are sensitive to changes in sodium concentration. These nanosensors will provide a new tool for sensitive and quantitative ion imaging.

US guidelines currently recommend 12 months of uninterrupted DAPT after implantation of DES. Prolonged and more powerful DAPT regimens have offered benefit by reducing VLST, but at the cost of increased risk of bleeding. There is an emerging need for new stents that are less dependent on prolonged

Item does not contain fulltext BACKGROUND: The efficacy and safety of polymer-free drug-eluting stents (DESs) in clinical practice is currently subject of debate; randomized trials (RCTs) conducted so far provided conflicting results or were underpowered to definitively address this question; we aimed to investigate the efficacy and safety profile of polymer-free vs. durable polymer DES by a comprehensive meta-analysis of RCTs. METHODS: MEDLINE, Google Scholar, EMBASE and Cochrane databases were searched for RCTs comparing polymer-free to durable polymer DES. Safety endpoints at short-term (1-year) were: death, myocardial infarction (MI) and stent thrombosis (ST); main efficacy endpoints were: target lesion revascularization (TLR) and target vessel revascularization (TVR). RESULTS: Eight RCTs including 6178 patients were included. No significant differences in mortality were observed between polymer-free and durable polymer DESs at both short- and long-follow up (OR [95% CI] = 0.79 [0.58-1.08], p = 0.14; and 0.80 [0.58-1.10], p = 0.17 respectively); polymer free and durable polymer DESs provided comparable short and long-term MI rates; at short-term: OR [95% CI] = 1.13 [0.83-1.54], p = 0.44 and at long-term: OR [95% CI] = 1.27 [0.87-1.85], p = 0.22. Similarly, these two different devices proved equally effective in regards to ST, TLR and TVR over the short and long follow-up period. CONCLUSIONS: Polymer-free DESs are as safe and effective as durable polymer DES; however, there is no evidence of any additional benefits provided by this new technology.

Drug release from poly(lactide-co-glycolide) (PLGA) microspheres is strongly determined by the pore structure of the par- ticles. This study examines how swelling-induced pore constriction delays the drug release and by which factors this process is con- trolled. Combination of different porosimetric and pycnometric methods enabled insight into the submicroscopic range of the pore structure and revealed that remarkably the polymer free volume plays a crucial role in drug release from PLGA microspheres. Surpris- ingly, the latter was shown to be inversely correlated to the degree of diffusional drug release. This can be explained by a swelling- induced constriction of the macroporous channel system in the microspheres which is related to the availability of free volume. The hole free volume was shown to be well controllable by the manufacturing conditions. Thus, the study deepens comprehension of the mechanism of drug release from biodegradable microparticles and offers an effective approach for controlling the release behavior. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39740.

Drug-eluting stents have shown an impressive reduction of in-stent restenosis for many years. However, stent thrombosis due to incomplete/late endothelialization has raised major safety concerns. To overcome these problems, we developed for the first time a polymer-free sirolimus-eluting antibody-coated stent (PFSEACS) by combining polymer free and endothelial progenitor cell-capture pro-healing approaches. In the first phase, the stents were prepared by loading sirolimus on the porous outer stent surface and directly fixing the anti-CD34 antibodies without any medium carriers on the blood contacting surface. The dose and elution of sirolimus, the amount and stability of anti-CD34 antibody immobilization, and the rate of CD34+ cell capture were evaluated. In the second phase, the stents were validated in an animal model of coronary arteries in pigs. The stent was observed to start collecting endothelial progenitor cells ~2 h after stent implantation and exhibited greatly enhanced endothelialization while maintaining an excellent anti-restenosis activity comparable to the polymer-free sirolimus-eluting stents. Overall, both in vitro and in vivo evaluations indicated that novel PFSEACSs exhibited facilitated endothelialization with excellent anti-restenosis activity and thus should merit further clinical studies.

Aims: Evaluation of safety and efficacy of ProNOVA XR, a new generation of polymer-free sirolimus eluting stents (SES), utilizing a pharmaceutical excipient for timed release of sirolimus from the XR platform. Methods and results: Safety and efficacy of ProNOVA XR coronary stent system was examined in EURONOVA prospective, single arm, multi-center registry of 50 patients with de novo native coronary lesions up to 28 mm in length in arteries between 2.25 and 4 mm. At 6-month, in-stent late lumen loss by QCA was 0.45 ± 0.41 mm and in-stent neointimal volume obstruction in the IVUS sub-study was 14 ± 11%. One-year clinical follow-up revealed a favorable safety profile, with 2% of in-hospital MACE and 6.4% of MACE from hospital discharge up to 12 months (including 1 cardiac death >30 days after stent implantation and 2 TLRs). According to the ARC definition, there was no definite or probable stent thrombosis and 1 possible stent thrombosis (2%) up to 12 months of clinical follow-up. Conclusions: In this preliminary evaluation, ProNOVA XR polymer-free sirolimus eluting stent system appeared safe with an early promise of adequate effectiveness in the treatment of de novo coronary lesions in up to 12 months of clinical, angiographic and IVUS follow-up.

Original manuscript June 20, 2012, We prove that under n[superscript 1/3] scaling, the limiting distribution as n → ∞ of the free energy of Seppalainen’s log-Gamma discrete directed polymer is GUE Tracy-Widom. The main technical innovation we provide is a general identity between a class of n-fold contour integrals and a class of Fredholm determinants. Applying this identity to the integral formula proved in Corwin et al. (Tropical combinatorics and Whittaker functions. http://arxiv.org/abs/1110.3489v3 [math.PR], 2012) for the Laplace transform of the log-Gamma polymer partition function, we arrive at a Fredholm determinant which lends itself to asymptotic analysis (and thus yields the free energy limit theorem). The Fredholm determinant was anticipated in Borodin and Corwin (Macdonald processes. http://arxiv.org/abs/1111.4408v3 [math.PR], 2012) via the formalism of Macdonald processes yet its rigorous proof was so far lacking because of the nontriviality of certain decay estimates required by that approach., National Science Foundation (U.S.) (Grant DMS-1056390), National Science Foundation (U.S.) (Grant DMS-1208998), Clay Mathematics Institute (Research Fellowship), Microsoft Research (Schramm Memorial Fellowship)

Non-exponential fluorescence decays due to the photochemical reaction of 10-cyano-9-tert-butyl-anthracene towards the Dewar isomer are analyzed to gain information on the free volume of a polymer glass (poly- n -butyl-methacrylate) at different temperatures. The simple model of a multiexponential fitting procedure is well suited to following the temperature dependence in the envelope of this distribution qualitatively, but it fails to detect finer structures. More demanding methods (maximum entropy and exponential series) result in at least trimodal distributions indicating preferred polymer free volume voids within a broad distribution. Increasing temperature favours the decay time range associated with the largest free volume void.

The investigators examined 326 pairs of angiograms from 2 randomized dose-finding (0.2 to 3.1 μg paclitaxel/mm2 of stent surface area) clinical trials of polymer-free paclitaxel-eluting stents in de novo lesions (the ASian Paclitaxel-Eluting stent Clinical Trial [ASPECT] and the European evaLUation of Taxol Eluting Stent [ELUTES]). A dose-dependent effect was observed: the largest dose of paclitaxel in the 2 trials resulted in a significantly larger proportion of lesions at follow-up with

Current literature has limited data on efficacy of polymer-free drug-coated stents (PFS) in treatment of coronary artery disease. The objective of our meta-analysis is to assess the efficacy of PFS compared to polymer-based drug-eluting stents (PBS) from currently published randomized controlled

Patients with diabetes mellitus (DM) remain at higher risk for stent restenosis and adverse cardiovascular events, even in the drug-eluting stent era. The polymer free (PF) Amphilimus-eluting stent (AES) has shown promising preliminary results in patients with DM. The aim of this study was to

Background Prolonged DAPT is undesirable in some patients. A biolimus-A9 drug-coated stent (BA9-DCS) has a rapid drug-elution profile potentially allowing shortened DAPT. Methods Data were gathered prospectively for 410 patients deemed to be at high risk of bleeding treated with a BA9-DCS stent at 2 UK centres and compared to usual PCI patients. Results BA9-DCS indications included warfarin therapy, age and anaemia. Patients receiving a BA9-DCS were older (71.6 ± 11.8 vs. 64.8 ± 11.6yrs, p Conclusions Early outcomes using polymer-free BA9 drug-coated stents are encouraging. Further studies are warranted.

Leaders Free Trial demonstrated that Biofreedom, a biolimus coated stent (BCS), to be superior to bare metal stent when used with a 1-month course of dual antiplatelet therapy (DAPT) in high bleeding risk patients (PT). BCS could be particularly useful in ST elevation myocardial infarction (STEMI)