Peg System Research Articles

Polylactide-Based Films with the Addition of Poly(ethylene glycol) and Extract of Propolis-Physico-Chemical and Storage Properties.

Polymeric films based on polylactide (PLA) with the addition of poly(ethylene glycol) (PEG) and a chloroformic extract of propolis were obtained. In the case of the studied films, polylactide (PLA) played the role of polymeric matrix and poly(ethylene glycol) was used as a plasticizer, while the extract of propolis was incorporated as a compound that could significantly affect the properties of the obtained materials, especially the water vapour permeation rate and the stability of the food products. Moreover, changes in structure, morphology, mechanical and storage properties as well as differences in colour, thickness and transparency after introducing propolis into the PLA–PEG system were determined. Based on the obtained results, it was established that the addition of the chloroformic extract of propolis significantly influences the most important properties taken into account during food packaging. It was also noticed that films with incorporated propolis were characterised by a significant improvement in the water vapour barrier property. Moreover, the obtained results prove that packaging containing a chloroformic propolis extract allow for the maintenance of the quality of the fruit stored for an extended period of time. To summarise, the application of a chloroformic propolis extract enables the formation of packaging materials that extend the shelf life of stored food products.

Evaporation Patterns of Dextran-Poly(Ethylene Glycol) Droplets with Changes in Wettability and Compatibility.

The dextran–PEG system is one of the most famous systems exhibiting phase separation. Various phase behaviors, including the evaporation process of the dextran–PEG system, have been studied in order to understand the physicochemical mechanism of intracellular phase separation and the effect of condensation on the origin of life. However, there have been few studies in dilute regime. In this study, we focused on such regimes and analyzed the pattern formation by evaporation. The specificity of this regime is the slow onset of phase separation due to low initial concentration, and the separated phases can have contrasting wettability to the substrate as evaporation progresses. When the polymer concentration is rather low (<5 wt%), the dextran–PEG droplets form a phase-separated pattern, consisting of PEG at the center and dextran ring of multiple strings pulling from the ring. This pattern formation is explained from the difference in wettability and compatibility between dextran and PEG upon condensation. At the initial dilute stage, the dextran-rich phase with higher wettability accumulates at the contact line of the droplet to form a ring pattern, and then forms multiple domains due to density fluctuation. The less wettable PEG phase recedes and pulls the dextran domains, causing them to deform into strings. Further condensation leads to phase separation, and the condensed PEG with improved wettability stops receding and prevents a formed circular pattern. These findings suggest that evaporation patterns of polymer blend droplets can be manipulated through changes in wettability and compatibility between polymers due to condensation, thus providing the basis to explore origins of life that are unique to the process of condensate formation from dilute systems.

Study of caffeine and coumarin extraction kinetics in an aqueous two-phase system based on polyethylene glycol 1500

Caffeine and coumarin are organic compounds of plant origin, which have biological activity and have found wide application in medicine, pharmaceutical, perfumery and food industries. Recovery of caffeine and coumarin from aqueous solutions using liquid-liquid extraction is the most effective method. In the present work the kinetic dependences of caffeine and coumarin in the aqueous two-phase system (ATPS) of PEG 1500 - Na2SO4 - H2O were experimentally obtained. It was established that equilibrium in the system is achieved after 17 minutes for caffeine and after 12 minutes for coumarin. The effect of ultrasound on the extraction rate of caffeine and coumarin in an aqueous two-phase system was also studied.

A fast microfluidic mixer enabling rapid preparation of homogeneous PEG and bicelle media for RDC in NMR analysis

Residual dipolar couplings (RDCs) are widely used in NMR for the investigation of protein structure and dynamics. However, commonly used RDC media (e.g., C12E5/Hexanol/H2O or PEG system, lipid bilayer or bicelle system) are unstable viscous liquids, making it challenging to obtain stable and homogeneous NMR samples by laborious manual operation. In this paper, we report a unique fishhook-shaped micromixer (FS-mixer) that enables fast and thorough mixing of high-viscosity PEG and bicelle media for RDC analysis. Numerical simulations and experimental characterizations proved that the micromixer could achieve a complete mixing of viscous liquids in 382.4 μs, improved significantly over current mixers. In compared to manually prepared RDC samples, the on-chip prepared samples have a better uniformity and alignment efficiency, and show more stable peak split in the 2H spectrum. As a proof of concept, we prepared a RDC sample for INSM1 ZF1-2 protein by using this FS-mixer. The IPAP-HSQC spectra demonstrated that this strategy can efficiently prevent the generation of low resolution and distorted spectra, which could facilitate further refinement of the NMR structure. This micromixer-assisted sampling method greatly simplifies the procedure, increases the media uniformity and stability, and shortens the time in RDC analysis. We believe it could serve as a useful tool in RDC-based NMR analysis.

Impact of Collagen Triple Helix Structure on Melanoma Cell Invadopodia Formation and Matrix Degradation upon BRAF Inhibitor Treatment.

A collagen-rich tumor microenvironment (TME) is associated with worse outcomes in cancer patients and contributes to drug resistance in many cancer types. In melanoma, stiff and fibrillar collagen-abundant tissue is observed after failure of therapeutic treatments with BRAF inhibitors. Increased collagen in the TME can affect properties of the extracellular matrix (ECM), including stiffness, adhesiveness, and interaction of integrins with triple helix forming nanostructures. Decoupling these biochemical and biophysical properties of the ECM can lead to a better understanding of how each of these individual properties affect melanoma cancer behavior and drug efficacy. In addition, as drug treatment can induce cancer cell phenotypic switch, cancer cell responsiveness to the TME can be dynamically changed during therapeutic treatments. To investigate cancer cell phenotype changes and the role of the cancer TME, poly(ethylene glycol) (PEG) hydrogels functionalized with collagen mimetic peptides (CMPs) is utilized, or an interpenetrating network (IPN) of type І collagen within the PEG system to culture various melanoma cell lines in the presence or absence of Vemurafenib (PLX4032) drug treatment is prepared. Additionally, the potential of using CMP functionalized PEG hydrogels, which can provide better tunability is explored, to replace the existing invadopodia assay platform based on fluorescent gelatin.

Imagery-based strategies for memory for associations

ABSTRACT Cued recall of word pairs is improved by asking participants to combine items in an interactive image. Meanwhile, interactive images facilitate serial-recall (Link Method), but even better when each item is imagined alongside a previously learned peg-word (Peg List Method). We asked if a peg system could support memory for pairs, hypothesising it would outperform interactive imagery. Tested with cued recall, five study strategies were manipulated between-subjects, across two experiments: (1) Both words linked to one peg; (2) Each word linked to a different peg; (3) Peg list method but studying as a serial list; (4) Interactive imagery (within-pairs); (5) Link Method. Participants were able to apply peg-list strategies to pairs, as anticipated by mathematical modelling. Error-patterns spoke to mathematical models; peg lists exhibited distance-based confusability, characteristic of positional-coding models, and errors tended to preserve within-pair position, even for inter-item associative strategies, suggesting models of association should incorporate position. However, the peg list strategies came with a speed–accuracy tradeoff and did not challenge the superiority of the interactive imagery strategy. Without extensive practice with peg list strategies, interactive imagery remains superior for associations. Peg strategies may excel instead in tasks that primarily test serial order or with extensive training.

Aqueous Triple-Phase System in Microwell Array for Generating Uniform-Sized DNA Hydrogel Particles.

DNA hydrogels are notable for their biocompatibility and ability to incorporate DNA information and computing properties into self-assembled micrometric structures. These hydrogels are assembled by the thermal gelation of DNA motifs, a process which requires a high salt concentration and yields polydisperse hydrogel particles, thereby limiting their application and physicochemical characterization. In this study, we demonstrate that single, uniform DNA hydrogel particles can form inside aqueous/aqueous two-phase systems (ATPSs) assembled in a microwell array. In this process, uniform dextran droplets are formed in a microwell array inside a microfluidic device. The dextran droplets, which contain DNA motifs, are isolated from each other by an immiscible PEG solution containing magnesium ions and spermine, which enables the DNA hydrogel to undergo gelation. Upon thermal annealing of the device, we observed the formation of an aqueous triple-phase system in which uniform DNA hydrogel particles (the innermost aqueous phase) resided at the interface of the aqueous two-phase system of dextran and PEG. We expect ATPS microdroplet arrays to be used to manufacture other hydrogel microparticles and DNA/dextran/PEG aqueous triple-phase systems to serve as a highly parallel model for artificial cells and membraneless organelles.

Buried Bumper Syndrome: A common complication of levodopa intestinal infusion for Parkinson disease

BackgroundPercutaneous endoscopic gastrostomy (PEG) is required for Levodopa/Carbidopa Intestinal Gel (LCIG) delivery in patients with advanced Parkinson's disease (PD) as well as for enteral feeding in a variety of neurological disorders. Buried Bumper Syndrome (BBS) is a serious complication of PEG. The frequency of BBS in patients receiving LCIG treatment has never been reported. ObjectivesTo compare the frequency of BBS in patients on LCIG treatment or on enteral feeding over the past 12 years and identify possible risk factors. MethodsWe reviewed prospectively recorded data from 2009 to 2020 on two case-series: LCIG-treated PD patients and non-PD patients on enteral nutrition. We identified all BBS incidences. Patients’ characteristics, clinical manifestations, BBS management, possible risk factors and outcomes were analyzed. ResultsDuring the 12 years, 35 PD patients underwent PEG insertion for LCIG infusion, and 123 non-PD patients for nutritional support. There were eight cases of BBS in six PD patients (17.1%). Six of them were effectively managed without treatment discontinuation. Of the enteral feeding patients, only one developed BBS (0.8%) (p < 0.001). We identified inappropriate PEG site aftercare, weight gain, early onset PD, longer survival, treatment duration, dementia and PEG system design as potential risk factors for BBS development. ConclusionsBBS occurs more frequently in LCIG patients than in patients receiving enteral feeding. If detected early, it can be successfully managed, and serious sequalae or treatment discontinuation can be avoided. Regular endoscopic follow-up visits of LCIG-treated patients and increased awareness in patients and clinicians are recommended.

PH and redox dual-sensitive drug delivery system constructed based on fluorescent carbon dots.

Herein, a pH and redox dual-responsive drug delivery system (CDs–Pt(iv)–PEG) was developed based on fluorescence carbon dots (CDs). In this system, cisplatin(iv) prodrug (Pt(iv)) was selected as a model drug to reduce toxic side effects. The aldehyde-functionalized monomethoxy polyethylene glycol (mPEG-CHO) was conjugated to CDs–Pt(iv) to form pH sensitive benzoic imine bond. Owing to the slightly acidic tumor extracellular microenvironment (pH 6.8), the benzoic imine bond was then hydrolyzed, leading to charge reversal and decrease in the hydration radius of the drug-carrying, which facilitated in vivo circulation and tumor targeting. Notably, the cytotoxicity of the drug delivery system on cancer cells was comparable to that of cisplatin, while the side effects on normal cells were significantly reduced. In addition, the system realized recognition of cancer cells by the high-contrast fluorescent imaging. In conclusion, the CDs–Pt(iv)–PEG system provided a promising potential for effective delivery of anticancer drugs and cancer cells screening.

Interplay between Glass Formation and Liquid-Liquid Phase Separation Revealed by the Scattering Invariant.

The interplay of the glass transition with liquid-liquid phase separation (LLPS) is a subject of intense debate. We use the scattering invariant Q to probe how approaching the glass transition affects the shape of LLPS boundaries in the temperature/volume fraction plane. Two protein systems featuring kinetic arrest with a lower and an upper critical solution temperature phase behavior, respectively, are studied varying the quench depth. Using Q we noninvasively identify system-dependent differences for the effect of glass formation on the LLPS boundary. The glassy dense phase appears to enter the coexistence region for the albumin-YCl3 system, whereas it follows the equilibrium binodal for the γ-globulin-PEG system.

Exchange rates in India: current account monetarism in a nonlinear context

Abstract The Indian exchange rate system has evolved from a pegged system to the current managed float. The study examines the presence of a long-run equilibrium in the monthly Indian exchange rate (Rs/USD) using a current account monetary model (or flexible price monetary model) while accounting for different nonlinearities over the period January 1993 to January 2014 (pre-inflation targeting period). The nonlinear adjustment to disequilibria is modelled using a nonlinear error correction model (NLECM). The nonlinear current account monetarism (CAM) model includes nonlinear transformations of long-run dynamics in the ECM to account for different nonlinearities: multiple equilibria (cubic polynomial function), nonlinear mean reversion (rational polynomial function), and smooth and gradual regime switches (exponential smooth transition autoregressive (ESTAR) function). The NLECM-ESTAR model outperforms other alternatives based on model and forecast performance measures, implying the existence of nonlinear mean reversion and smooth transition across different periods of overvaluation and undervaluation of the exchange rate. This implies the presence of asymmetric adjustment to the movements from the long-run equilibrium, but the nature of such transitions is smooth and not abrupt. The paper also establishes the uniqueness of the long-run equilibrium. A comparison to the sticky price monetary model could not be made due to stationary exchange rate disequilibrium.

Simulation of adaptive power management circuit for hybrid energy harvester and real-time sensing application

Many wireless sensor network (WSN) applications, nowadays, require real-time communication, which demands cautious design consideration to resolve inherent conflicts between energy efficiency and the need to meet Quality of Services (QoS), such as end-to-end delay communications. Numerous innovative solutions are proposed such as Real-time Power-Aware Routing (RPAR) protocol, which dynamically adapts transmission power to meet specified communication delays at low energy cost. Hence, to enable real-time communication with RPAR protocol, an adaptive Power Management Circuit (PMC) using hybrid energy harvester to support WSN real-time communication is proposed. In this paper, a high-level architecture of the proposed PMC is discussed, which consists of Thermal Energy Generator (TEG), and Piezoelectric Energy Harvester (PEG) as energy providers, with low-power Maximum Power Point Tracking (MPPT) feature enabled. Preliminary simulations which analyze and characterize TEG and PEG system are conducted separately to determine the optimal design parameters to support the conventional WSN QoS requirement. Next, both systems will be integrated into a single PMC implementation prior to fabrication and lab characterization.

Electrical Properties of PVA:PVP:PEG based Blend Polymer Electrolytes

This is a novel approach to get polyblend films with improved properties such as ionic conductivity and dielectric strength. Different ratios of PEG (5%, 10%, 15%, 20%, 25%, 30%) are added with optimized PVA: PVP ratio. PVA: PVP: PEG based BPEs are prepared by using solution casting method. The polymer PEG act as a plasticizer and chemically stable in air.The prepared electrolytes are characterized by XRD, FTIR and ionic conductivity studies. The XRD analysis shows amorphous nature of the polyblend electrolytes. Dielectric analysis is carried out for the BPEs. The higher conductivity is obtained for 20% PEG added polyblend electrolytes and it is 9.0x10-9 S/Cm. Thus, PVA: PVP: PEG (40:40:20) system is confirmed as optimized one for further studies to enhance the ionic conductivity

Investigations on the thermal and electrical conductivity of polyethylene glycol-based CuO and ZnO nanofluids

ABSTRACT In this experimental work, three different types of nanofluids were evaluated for their stability using dynamic light scattering and particle morphological study using scanning electron microscopy. The nanofluids used in this study are zinc oxide (ZnO) nanoparticle in water and 5 wt% polyvinylpyrrolidone (PVP) as a dispersant, and ZnO with polyethylene glycol (PEG 600) and CuO with PEG 600 with 5 wt% PVP at different concentration of 0.1, 0.3 and 0.5 wt%. Thermal and electrical conductivities were determined by KD-2 Pro® and PC 700 Eutech®. The result shows better enhancement in the thermal and electrical conductivity in the ZnO+PVP+Water system, followed by the CuO+PVP+PEG and ZnO+PEG systems. The highest percentage enhancement in thermal conductivity found to be 35.5% of ZnO+ PVP+water systems. The thermal conductivity results were compared with a theoretical model and show good agreement with results predicted by the model. The proposed model of Nan et al. (1997) is based on a hypothesis regarding the physical mechanism in heat transfer for nanofluids. This study is expected to form the basis for the development of nanofluid-based technologies with PEG as the primary additive in the upstream oil and gas industry especially in gas hydrates and drilling technology.

Eco-Innovation in Reusing Food By-Products: Separation of Ovalbumin from Salted Egg White Using Aqueous Two-Phase System of PEG 1000/(NH₄)₂SO₄.

For the purpose of reducing pollution and the rational use of salted egg white, which is a byproduct of the manufacturing process of salted egg yolk, an aqueous two-phase system (ATPS) composed of polyethylene glycols (PEG 1000) and (NH4)2SO4 was investigated to selectively separate ovalbumin (OVA) from salted egg white. With the aim of optimizing the selective separation of OVA using ATPS, a response surface method (RSM) experiment was carried out on the basis of a single-factor experiment. The OVA was characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS–PAGE), reversed-phase high-performance liquid chromatography (RP-HPLC), liquid chromatography-nano electrospray ionization mass spectrometry (Nano LC-ESI-MS/MS), and Fourier transform infrared spectroscopy (FT-IR). Under the optimal conditions, the recovery yield of OVA through ATPS (Y) and the purity of OVA (P) could reach 89.25% and 96.28%, respectively. In conclusion, OVA was successfully separated from the salted egg white by PEG/(NH4)2SO4 ATPS.

Should Indonesia adopt a basket currency regime?

Exchange rate regime is a system in which a country manages its currency about other currencies and the foreign exchange market. Currently, there are two major types of exchange rate regimes, i.e., free-float system and pegged system. Many countries, including Indonesia, adopted the free-float system since it is believed as the best regime for absorbing external economic shocks. However, some economists argued that a moderate exchange rate regime, such as currency basket system, is a better approach for achieving the government's goals. The research aims to provide an arrangement for optimal basket weights of Indonesian currency basket to minimise GDP volatility as well as exchange rate volatility. We develop an optimisation model in the extension of Yoshino et al. (2017) by adding five currencies in the basket. We found that the weight currencies in the free-float regime would reflect the trade intensities of the respective countries. Further, the government should monitor the change of exchange rates of currencies in the foreign reserves and change the weight accordingly. In addition, we also found that, whether the government implementing basket currency regime or free-float regime, it will make no significant differential effect on GDP gap volatility.

Effective or Manipulated Crawling Pegged? Examining the Efficiency of China’s Foreign Exchange Markets

ABSTRACTThrough data on the balance of payments, this article examines the performance of the crawling peg system in China’s foreign exchange markets. We are interested in whether the exchange rates are steered by the market fundamentals or manipulation. We investigate the changes in market efficiency for the RMB against 12 major currencies in the past decade. Our findings reveal that even with a small floating band in China’s foreign exchange markets, if the market allows the exchange rate to adjust according to the price mechanism, then market efficiency does improve significantly. When the RMB was pegged to the USD at 6.83 during the global financial crisis, there was a severe market failure. That also occurred in 2014, when the China government began to depreciate the RMB to stimulate exports.

An Ethylenediamine‐based Switch to Render the Polyzwitterion Cationic at Tumorous pH for Effective Tumor Accumulation of Coated Nanomaterials

AbstractPolyzwitterions are employed as coating polymers for biomaterials to induce an antifouling property on the surface. Fine‐tuning the betaine structure switches the antifouling property to be interactive with anionic tissue constituents in response to a tumorous pH gradient. The ethylenediamine moiety in the carboxybetaine enabled stepwise protonation and initiated the di‐protonation process around tumorous pH (6.5). The net charge of the developed polyzwitterion (PGlu(DET‐Car)) was thus neutral at pH 7.4 for antifouling, but was cationic at pH 6.5 for interaction with anionic constituents. Quantum dots coated with PGlu(DET‐Car) exhibited comparable stealth and enhanced tumor accumulation relative to the PEG system. The present study provides a novel design of smart switchable polyzwitterion based on a precise control of the net charge.

An Ethylenediamine‐based Switch to Render the Polyzwitterion Cationic at Tumorous pH for Effective Tumor Accumulation of Coated Nanomaterials

Polyzwitterions are employed as coating polymers for biomaterials to induce an antifouling property on the surface. Fine-tuning the betaine structure switches the antifouling property to be interactive with anionic tissue constituents in response to a tumorous pH gradient. The ethylenediamine moiety in the carboxybetaine enabled stepwise protonation and initiated the di-protonation process around tumorous pH (6.5). The net charge of the developed polyzwitterion (PGlu(DET-Car)) was thus neutral at pH 7.4 for antifouling, but was cationic at pH 6.5 for interaction with anionic constituents. Quantum dots coated with PGlu(DET-Car) exhibited comparable stealth and enhanced tumor accumulation relative to the PEG system. The present study provides a novel design of smart switchable polyzwitterion based on a precise control of the net charge.

Optimization of polyol production via liquefaction from Acacia mangium and analysis of the polyols by traditional methods and two-dimensional correlation spectroscopy

Abstract The aim was to optimize the liquefaction conditions of Acacia mangium wood flour with polyethylene glycol (PEG#400) as the solvent in the presence of sulfuric acid as a catalyst under atmospheric pressure. Reaction time (30–180 min), temperature (130–170°C), and the solvent ratio (PEG/glycerol=0–25%) were varied to obtain the lowest residue content. The resulting polyol was characterized by their hydroxyl number (OHN), acid number (AN), viscosity, molecular weight (Mw), thermogravimetric analysis, Fourier transform infrared (FT-IR) and two-dimensional correlation spectroscopy (2D-COS). The OHN was lowered, AN and Mw were elevated as a function of increasing the reaction temperature and the time. Introducing glycerol in the PEG system markedly increased the OHN, AN and viscosity of the liquefied wood. The optimum condition was 80/20% ratio of PEG/glycerol at 150°C in 150 min leading to a 75% liquefaction yield. The 1730 cm−1 band was indicative for the esters in the liquefied product. The 2D-COS analysis showed that lignin is easily liquefied at high temperatures and a decreasing amount of PEG, and that the presence of glycerol significantly enhanced the 1730 cm−1 band.