Changes In Poly Research Articles

Physical and Morphological Changes of Poly(tetrafluoroethylene) after Using Non-Thermal Plasma-Treatments.

A commercial formulation of poly(tetrafluoroethylene) (PTFE) sheets were surface modified by using non-thermal air at 40 kHz frequency (DC) and 13.56 MHz radiofrequency (RF) at different durations and powers. In order to assess possible changes of PTFE surface properties, zeta potential (ζ), isoelectric points (IEPs) determinations, contact angle measurements as well as Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) imaging were carried out throughout the experimentation. The overall outcome indicated that ζ-potential and surface energy progressively changed after each treatment, the IEP shifting to lower pH values and the implicit differences, which are produced after each distinct treatment, giving new surface topographies and chemistry. The present approach might serve as a feasible and promising method to alter the surface properties of poly(tetrafluoroethylene).

Strengthening Effects of Zn Addition on an Ultrahigh Ductility Mg-Gd-Zr Magnesium Alloy.

A newly developed Mg-2Gd-0.5Zr-xZn (x = 0.5, 1.0, 2.0, 3.0 wt %) alloy system exhibits significant strengthening by doping with Zn. In order to understand the strengthening mechanism, the microstructure, texture evolution, and mechanical properties of ultrahigh ductility Mg-2Gd-0.5Zr alloys with a Zn addition were systematically investigated. The addition of Zn results in the formation of Mg-Gd-Zn intermetallic compounds along grain boundaries, which encourages grain refinement during hot extrusion via the particle stimulated nucleation (PSN) mechanism. Furthermore, during texture sharpening the pole changes from <201> to <010>, which also occurred in the extruded alloys with Zn addition, which is unfavorable for the basal slip and tensile twinning. Mg-2Gd-0.5Zr-3Zn shows well-balanced strength and ductility with a tensile yield strength (YS) and ultimate tensile strength (UTS) of 285 and 314 MPa, accompanied by a high tensile elongation of 24%. They are superior to those of commercial AZ31. The enhanced strength is attributed to grain refinement, precipitation strengthening, and texture sharpening induced by alloying with Zn. The research result is also of great value to the development of low rare-earth, high strength, and high room temperature ductility magnesium alloy.

A Novel Line-Start Permanent Magnet Synchronous Motor With 6/8 Pole Changing Stator Winding

Line-start permanent magnet synchronous motors (LSPMSMs) have become superior to induction motors in general industrial applications due to their high efficiency, improved power factor, and enhanced torque density. However, the LSPMSM suffers the poor starting torque owing to the existence of the braking and pulsating torque at start-up, which seriously plagues its development. Therefore, this paper presents a novel LSPMSM with 6/8 pole changing stator windings, which can fundamentally improve the starting capability. At the beginning of the starting, the 6-pole stator windings are energized, whereas the rotor permanent magnets are 8 poles, so the braking torque and pulsating torque can be highly decreased. When the motor reaches a certain speed, the stator winding changes to 8 poles to pull into synchronization and stable operation. The design of the 6/8 pole changing winding is presented based on the slot-number phase diagram method. Then, the starting process of the conventional and the proposed pole changing LSPMSMs are analyzed and compared. Through the calculation of impedance parameters and the analysis of magnetic fields at the start-up, the torque components are calculated utilizing the analytical calculation method. Finally, the experiments are carried out to verify the validity and superiority of the proposed design and method.

Study Regarding the Defense Expenditure Analysis in Nato

Abstract Armed conflicts are a reality of the present world. Military power is an active actor in domestic and international relations. Defense must have the financial allocations necessary to sustain a flexible and modern army. The macroeconomic and geostrategic factors, including the change of power poles from the West to the East, the demographic changes and the limited resources are elements that will deeply reconfigure the trends in military expenditure. This is the case in less developed areas of the world where trends will bring instability and will put additional, internal and external pressure on the challenges of defense and security. NATO countries have assumed the 2% of GDP target for defense expenditure, but are making great efforts to reach this level. In 2016, only 4 out of 29 NATO members, or 14% reached the target of 2% of GDP for military expenditure and 20 out of 29 NATO countries spent less in absolute terms in 2016 compared to 2014

Structural changes in Poly(lactic acid)–zeolite nanocomposites exposed to 60Co gamma rays

ABSTRACTPoly(lactic acid) (PLA) nanocomposites containing 3%, 5% and 7% zeolite used in the present research study were prepared by solution casting. The PLA nanocomposites were structurally characterized by Scanning Electron Microscopy and Fourier-transform infrared spectroscopy. The effects of the gamma radiation at the absorbed doses of 10, 15 and 20 kGy on the structures and thermal properties of the nanocomposites were investigated in a tetrahydrofuran solvent. Thermodecomposition tests and analyses were carried within 30–500°C range at the rate of 10°C min−1 by thermogravimetric analysis (TG). The activation energies for thermal degradation of the nanocomposites were calculated from their TG data by Flynn–Wall–Ozawa method. The G values of the nanocomposites were calculated based on molecular weights which were measured by means of gel permeation chromatography before and after the gamma irradiation. The Ea and molecular weight results showed that addition of zeolite to the PLA affected the radiation resistance of the polymer.

Poly(vinyl Chloride) Photostabilization in the Presence of Schiff Bases Containing a Thiadiazole Moiety.

Five Schiff bases containing a thiadiazole moiety have been used as poly(vinyl chloride) photostabilizers at low concentrations. The efficiency of Schiff bases as photostabilizers was investigated using various techniques, for example, the changes in poly(vinyl chloride) infrared spectra, molecular weight, chain scission quantum yield, and surface morphology were monitored upon irradiation with an ultraviolet light. Evidently, all the additives used inhibited poly(vinyl chloride) photodegradation at a significant level. The most efficient Schiff base exhibited a high level of aromaticity and contained a hydroxyl group. It seems possible that such photostabilization could be due to the direct absorption of ultraviolet radiation by the additives. In addition, Schiff bases could act as radical scavengers and proton transfer facilitators to stabilize the polymeric materials.

The effect of alkylated graphene oxide on the crystal structure of poly(4‐methyl‐1‐pentene) during uniaxial deformation at high temperature

This work discussed the deformation‐induced structure changes of poly(4‐methyl‐1‐pentene)/alkylated graphene oxide (TPX/GO‐ODA) nanocomposites during uniaxial stretching at a certain temperature (80°C). Based on crystalline behaviors of samples during deformation, the strain range could be divided into two regions. Within Region I, the melting temperature of TPX rose with strain; and the figures for TPX/GO‐ODA were volatile; the crystallinity of these two samples showed a similar trend. Within Region II, melting points of two samples did not experience any remarkable changes; the figure for TPX/GO‐ODA was higher than TPX. However, the crystallinity of two samples had a similar pattern; and the figures for nanocomposites showed a moderate increase and reached the plateau region at a greater strain. Wide‐angle X‐ray scattering demonstrated that crystal structure of samples could be destroyed during deformation. Small‐angle X‐ray scattering showed that the spherulitic structure of samples would transform into fibrillar structure. And the fibrillar structure size of TPX/GO‐ODA was smaller than that of TPX according to Guinier approximation. All data revealed that GO‐ODA not only prevented crystal structures from being destroyed within Region I, but also it might restrict rearrangements of molecular chains and crystal fragment within Region II. POLYM. COMPOS., 40:E493–E500, 2019. © 2018 Society of Plastics Engineers

Maximizing the Output Power of Wind-Driven Grid-Connected Cage Induction Generator through Pole Control

In this research, a cage induction generator has been linked to the grid and driven with a wind-turbine to generate electrical power. The cage generator has been used in place of the costly slip-ring generator. The performance characteristics of the cage induction generator have been ameliorated through changing its number of poles to comply with the level of the wind speed to maximize the mechanical power extracted from the wind. Pole changing has been achieved employing pole-amplitude modulation technique resulting in three sets of pole numbers. The results proved the feasibility and effectiveness of the suggested method, as the proposed technique led to driving the generator, and consequently the wind-turbine at speeds close or equal to those satisfying the optimum tip-speed ratio which corresponds to the point of maximum mechanical power.

Image analysis as a useful tool for fast detection of dimensional and structural changes of poly(ethylene terephthalate) containers

The aim of this paper is to present image analysis as a useful technique for fast, reliable and non-destructive detection of dimensional and structural changes in polymers. The possibility of applying image analysis was demonstrated in the case of solvent-induced crystallization of poly(ethylene terephthalate) (PET) containers filled with commonly used organic solvents: chlorobenzene, isophorone, xylene, Espesol, Shellsol A 100, Solvesso 150, propylene glycol, glycerin and water and subjected to the storage stability test at 54 ?C for 14 days (CIPAC 1-MT 46.1.3). In addition, the obtained results were analyzed using one-step analysis of variance (ANOVA) combined with the Duncan?s statistical test (p&lt;0.05). According to the achieved results, three main impacts of the presented paper could be distinguished: 1) dimensional and transparency changes could be precisely followed by image analysis in both following cases: for small changes in water, as well as for significant ones in chlorobenzene; 2) a correlation between the changes in the degree of crystallinity and transparency could be obtained without the continuous material testing by DSC; 3) image analysis is potentially applicable for assessment of other crystalline polymers.

Aggressive Posterior Retinopathy of Prematurity (AP-ROP)

Aggressive retinopathy of prematurity (AP-ROP) has subtle clinical findings that may preclude early diagnosis and treatment. Premature infants with AP-ROP have a progressive clinical course and may benefit from early laser treatment. Although subjective in nature, plus disease, and any posterior pole changes especially at the border of the vascular and avascular retina should be carefully evaluated, keeping AP-ROP in mind in especially high-risk preterm babies.

基于SVM的状态反馈故障诊断技术

本文利用SVM对系统极点进行分类，区分出状态反馈系统无故障和发生故障时分别产生的极点。并利用网格搜寻法寻找最优参数，对极点分类方法进行建模。为了实现对系统极点变化的实时监测，本文给出了一种通过系统状态估算系统极点的新方法。在给出故障诊断模型的基础上，同时对相应的故障设计可靠控制器。最后通过算例验证极点估算方法的正确性和故障诊断的准确性以及可靠控制器的有效性。 In this paper, SVM is used to classify the poles of the system, and the poles generated by the state feedback system without faults and faults are distinguished. And the grid search method is used to find the optimal parameters, and the pole classification method is modeled. In order to realize the real-time monitoring of system pole change, a new method to estimate the system poles by system status is presented. On the basis of the fault diagnosis model, a reliable controller is designed for the corresponding faults. Finally, an example is given to verify the correctness of the pole estimation method, the accuracy of the fault diagnosis and the effectiveness of the reliable controller.

Radical Institutional Economics and Fakery for the 21st Century

The article summarises some results of the discussions about radical institutional economics (RIE) for the 21st century. The discussions took place at the 38th Conference of the Association for Institutional Thought, held in April 2017 (San Francisco, California, US). The contribution of radical institutional economists of the 1990s in the development of institutional thought is presented in the article. The works of William M. Dugger – the founder of RIE – are stressed, as well as the roles of other radical institutionalists such as Edythe Miller, J. Ron Stanfield, Ron Phillips, Dell Champlin, Janice Peterson, Charles Whalen, Doug Brown, Rick Tilman, Louis Junker and Howard Sherman. The reasons for the reintroduction of radical institutional economics onto the agenda in the modern US are considered, among them being the increasing fakery in economies and the growth of inequality in incomes and distribution of economic benefits. The article then suggests a hypothesis that an external factor in the radicalisation of science and public consciousness in Western and other countries is associated with a change in world leaders and poles of growth, and is a turning point in history. It is argued that the power of countries in which the X-matrix dominates is beginning to surpass the influence of countries where the Y-matrix dominates.

Multivariable methods applied to FTIR: A powerful technique to highlight architectural changes in poly(lactic acid)

The structural modifications of a commercially available poly(lactid acid) grade were induced through reactive extrusion using a multi-epoxide reactive agent in a pilot plant. The statistical nature of the chemical reactions led to the generation of several types of non-uniform molecular architectures. Even though conventional spectroscopic (NMR) or chromatographic (SEC-static light scattering) techniques are placed at the forefront of the molecular characterization, both methods usually failed in characterizing non-uniform structures. In this study, a promising approach was applied to automatically classify modified PLA samples. It is based on the analysis of FTIR spectral data by means of multivariable methods, including feature extraction and classification algorithms. The fast and accurate results presented in this paper show the potential of the proposed approach.

Novel grid combined with peripheral distortion correction for ultra-widefield image grading of age-related macular degeneration.

PurposeEyes with age-related macular degeneration (AMD) often harbor pathological changes in the retinal periphery and perimacular region. These extramacular changes have not been well classified, but may be phenotypically and functionally relevant. The purpose of this study was to demonstrate a novel grid to systematically study peripheral retinal abnormalities in AMD using geometric distortion-corrected ultra-widefield (UWF) imaging.MethodsThis is a cross-sectional observational case series. Consecutive patients with AMD without any other coexisting vitreoretinal disease and control patients over age 50 without AMD or any other vitreoretinal disease were imaged using Optos 200 Tx. Captured 200° UWF images were corrected for peripheral geometric distortion using Optos transformation software. A newly developed grid to study perimacular and peripheral abnormalities in AMD was then projected onto the images.ResultsPeripheral and perimacular changes such as drusen, retinal pigment epithelium changes and atrophy were found in patients with AMD. The presented grid in conjunction with geometric distortion-corrected UWF images allowed for systematic study of these peripheral changes in AMD.ConclusionWe present a novel grid to study peripheral and posterior pole changes in AMD. The grid is unique in that it adds a perimacular zone, which may be important in characterizing certain phenotypes in AMD. Our UWF images were corrected for geometric peripheral distortion to accurately reflect the anatomical dimensions of the retina. This grid offers a reliable and reproducible foundation for the exploration of peripheral retinal pathology associated with AMD.

Spectroscopic studies of dopant-induced conformational changes in poly (3-hexylthiophene) thin films

Abstract

Concentration-induced discoloration properties of poly(alkoxynaphthalene)s synthesized by solid-state oxidative coupling polymerization

Poly(alkoxynaphthalene)s were synthesized by grinding 2-alkoxynaphthalenes with FeCl3 as the oxidant at room temperature via solid-state oxidative coupling polymerization. Based on the structural characterization and analysis, the condensed structure of 1,4-linked polynaphthalenes is the dominant structure of the polymer, accompanied with the formation of intramolecular coupling. The polymers not only exhibit perfect heat-resistant property, but also show the concentration-induced discoloration property. With the continuously increasing polymer concentrations, the maximum fluorescence bands were observed from the ultraviolet region to 520nm, eventually red shifting to 620nm at the polymer concentration above 0.1mgmL−1. Moreover, the choice of solvent and the extended side-chains can affect the fluorescence spectral changes. In combination with the fluorescence spectral changes of poly(alkoxynaphthalene)s in PMMA films, the concentration-induced discoloration property is mainly dependent on a transition from twisted conformations to planar structures and the formation of polymer aggregates. Moreover, these polymers exhibit obvious enhanced emissions and on/off fluorescent switching which sense THF vapor. It is suggested that poly(alkoxynaphthalene)s are potential materials for fabrication of fluorescence sensors to detect THF efficiently.

Role of cleavage and polyadenylation specificity factor 100: anchoring poly(A) sites and modulating transcription termination.

CPSF100 is a core component of the cleavage and polyadenylation specificity factor (CPSF) complex for 3'-end formation of mRNA, but it still has no clear functional assignment. CPSF100 was reported to play a role in RNA silencing and promote flowering in Arabidopsis. However, the molecular mechanisms underlying these phenomena are not fully understood. Our genetics analyses indicate that plants with a hypomorphic mutant of CPSF100 (esp5) show defects in embryogenesis, reduced seed production or altered root morphology. To unravel this puzzle, we employed a poly(A) tag sequencing protocol and uncovered a different poly(A) profile in esp5. This transcriptome-wide analysis revealed alternative polyadenylation of thousands of genes, most of which result in transcriptional read-through in protein-coding genes. AtCPSF100 also affects poly(A) signal recognition on the far-upstream elements; in particular it prefers less U-rich sequences. Importantly, AtCPSF100 was found to exert its functions through the change of poly(A) sites on genes encoding binding proteins, such as nucleotide-binding, RNA-binding and poly(U)-binding proteins. In addition, through its interaction with RNA Polymerase II C-terminal domain (CTD) and affecting the expression level of CTD phosphatase-like 3 (CPL3), AtCPSF100 is shown to potentially ensure transcriptional termination by dephosphorylation of Ser2 on the CTD. These data suggest a key role for CPSF100 in locating poly(A) sites and affecting transcription termination.

Structural Changes in Poly(trimethylene adipate) and Poly(trimethylene succinate) During Melt Crystallization Studied Using In Situ Infrared Spectroscopy.

This paper investigates the structural changes occurring in poly(trimethylene adipate) (PTAd) and poly(trimethylene succinate) (PTSu) during melt crystallization using differential scanning calorimetry (DSC) and in situ Fourier transform infrared (FT-IR) spectroscopy. Cooling thermograms revealed that PTAd had a faster crystallization rate than PTSu. Infrared (IR) bands of the two polyesters were assigned by correlating with the IR bands of polymers containing the trimethylene and the diacid segments. The bands at 1478, 1459, 1393, and 1364 cm-1 in PTAd and 1475, 1459, 1393, and 1361 cm-1 in PTSu were designated to the CH2 of the trimethylene segment. Changes in the IR band absorbance intensities of the CH2 and the C-O-C groups were monitored with time during melt crystallization. Structural changes of the trimethylene and diacid segments of PTAd occurred synchronously, while in PTSu the two segments changed sequentially. Normalized band intensities showed a time lag between the trimethylene and succinic acid segments. The acid segment showed a faster change compared to the trimethylene segment. Fourier transform infrared spectroscopy is shown to be a useful technique to study conformational changes during crystallization in polymers.

Evaluation of interfacial region of microphase-separated SEBS using modulated differential scanning calorimetry and dynamic mechanical thermal analysis

The continuous structural changes of Poly(styrene-b-ethylene-butylene-b-styrene) [SEBS] due to the effect of temperature are hard to evaluate using conventional differential scanning calorimetry (DSC). This paper presents an accurate and simple way to evaluate microstructural and glass transitions of SEBS using modulated differential scanning calorimetry (MDSC). The weak crystalline nature of –(CH2-CH2)–n in the ethylene-butylene (EB) block melted around 36 °C. The premature molecular moment and Tg of the styrene block were at 62 °C and 96 °C, respectively. The interfacial region at high temperature was explained with respect to order-order transition (OOT) at 144 °C and a prominent Order-Disorder Transition (ODT) at around 202 °C. Dynamic mechanical thermal analysis (DMTA) and dynamic mechanical rheological testing (DMRT) measurements also revealed that the Tg of the PS transition were consistent at around 96 °C.

Reprocessability of PHB in extrusion: ATR-FTIR, tensile tests and thermal studies

Abstract Mechanical recycling of biodegradable plastics has to be encouraged, since the consumption of energy and raw materials can be reduced towards a sustainable development in plastics materials. In this study, the evolution of thermal and mechanical properties, as well as structural changes of poly(hydroxybutyrate) (PHB) up to three extrusion cycles were investigated. Results indicated a significant reduction in mechanical properties already at the second extrusion cycle, with a reduction above 50% in the third cycle. An increase in the crystallinity index was observed due to chemicrystallization process during degradation by chain scission. On the other hand, significant changes in the chemical structure or in thermal stability of PHB cannot be detected by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA), respectively.