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Purpose: This aimed to compare the effect of family-centered (FC) empowerment model and participatory care model on quality of life (QoL) in children with thalassemia major. Methods: This quasi-experimental pre- post-test study was conducted on three groups, including the FC empowerment, the participatory care model and control. The study samples consisted of thalassemia children who met the inclusion criteria. The samples were randomly divided into three by lot. Data was collected using a demographic questionnaire and the Pediatric Quality of Life Inventory. The control group received routine care only. The intervention program was implemented for four sessions of 45 minutes during two weeks (two sessions per week) in the conference hall of the hospital. The data were analyzed analysis of covariance with the Bonferroni post hoc test. The significance level was set at < 0.05. Results: A significant difference in the means of physical (p=0.002), social (P

A perfect infrared spectrum absorber in a cylindrical groove array perforated in a metallic layer and followed by vanadium dioxide (VO2), a phase-change material, is introduced and analytically investigated. The phase-change material can change from insulator to metallic phase if proper stimuli, such as heat, voltage, and current, are applied, herein the phase change initiated by heating beyond the phase-transition temperature of VO2. The large refractive index variations between two phases enable the manipulation of optical properties. Simulation results reveal that in the metallic phase, the absorption is suppressed to one third, while VO2 works as a transparent medium for impinging light, and perfect absorption is observed in the insulation phase. The process is reversible in a picosecond time scale. Given the structure symmetry, the absorption is irreverent to impinging light polarization. The thermally controlled infrared absorber may have applications in various optical systems, like imaging and sensing, due to its simple and easy fabrication process.

Zinc oxide (ZnO) nanorods (NRs) were obtained by oxidation of Zn thin layers, prepared by thermal evaporation method under electric field, at different times of 2.5, 5, 7.5 and 10 h. The crystal structure of samples was investigated using X-ray diffraction (XRD) measurement, which showed samples had a wurtzite hexagonal structure. In addition, field emission scanning electron microscopy (FESEM) indicated that with an increase in the oxidation time, the NRs diameter increased too. Elemental analysis of samples was performed using energy-dispersive X-ray spectroscopy (EDX) which clearly confirmed the presence of Zn and O with an atomic ratio of 1:1. Further, Raman spectra of samples verified wurtzite hexagonal phase due to high- and low-frequency vibration of E2 modes at room temperature and showed that with an increase in the oxidation time, the lattice defects decreased whereas crystal quality of samples increased. Optical properties of samples were determined by UV spectroscopy and demonstrated that when the oxidation time was added, the band gap energy of ZnO NRs decreased, which was attributed to the increase in crystallite size.

This study deals with an experimental investigation of structural and magnetic properties of LaNi5 and MmNi4.7Al0.3 (Mm consists of 66.6 wt% Ce and 33.3 wt% La) hydrogen storage alloys. LaNi5 and MmNi4.7Al0.3 alloys were prepared by vacuum induction melting method and then hydrogenated under 50 bar hydrogen gas pressure. The structure of the samples, before and after hydrogenation, was probed by X-ray diffraction (XRD) analysis which showed that all the samples have a single phase hexagonal crystal structure (CaCu5-type). Then X-ray fluorescence (XRF) measurement was used to investigate the chemical compound of the as-prepared samples. The study of the magnetic properties of samples indicated that the as-prepared alloys are weakly ferromagnetic or paramagnetic, while the hydrogenation process causes ferromagnetic behavior of samples to intensify. Honda-Arrott plot analysis exhibited that substitution of Al for Ni and Ce for La in the as-prepared samples reduces the magnetic susceptibility from 4.8 × 10−6 to 3.06 × 10−6 emu/gOe. Magnetic anisotropy of the hydrogenated samples in a high magnetic field was studied using the law of approach to saturation. The results indicated that the magnetic anisotropy and anisotropy field increase by the replacement of Ni and La with Al and Ce respectively.

Real-space methods of characterizing high-performance fibers’ inherent morphologies will greatly enhance our understanding of the key structural features within fibers and their impacts on mechanical performance. Here, we report on structure–property correlations of two new classes of commercial DuPont Kevlar fibers, termed “K29 sample test” and “K49 sample test,” as well as conventional K29 and K49 fibers.* Through multifrequency atomic force microscope scans of internal fiber surfaces prepared by a focused ion beam notch technique, we directly capture nano- and microstructural features that define the inherent structures of these fibers. Integrating these findings with X-ray scattering experiments, we relate crystallographic and real-space measurements to each other, highlighting how multiscale structural motifs manifest within fibers. By carrying out tensile tests on single fibers drawn from the same tows, we also glean new insights into the structure–property relationships that dictate the mechanical behavior of these fibers.

An active ultra-compact plasmonic waveguide composed of a subwavelength slit and perforated in vanadium dioxide (VO 2 ) followed by a metallic layer is proposed and numerically analyzed. Refractive index variation of VO 2 by external stimuli provides a feasible way for tuning the optical properties of the waveguide. Varying the refractive index of VO 2 corresponds with changing the phase of VO 2 to the metallic state (“on” state). Consequently, the entire structure becomes a typical metal–insulator–metal (MIM) waveguide that routes the incident light through the slit. In addition, during the “off” state, the incident light thereby propagates in the slit and VO 2 medium and mitigates rapidly. By adding a MIM waveguide attached to the Fabry–Perot (FP) cavity, spectrally wide stopband and passband filtering features in telecommunication frequency regime are demonstrated. Tailoring the resonance wavelength can be performed through the geometrical parameters. Such active plasmonic waveguides with high transmission, coupling, and compact size can be utilized in future fully integrated all plasmonic chip technology.

In recent years, metal oxide semiconductors have been one of the most remarkable subjects in science and technology. Present research investigates the growth and characterization of Zinc Oxide (ZnO) nanorods (NRs) as one of the metal oxide semiconductors with a broad range of applications. In this work, ZnO NRs preparation includes two steps. In the first step, Zn thin layers were deposited by thermal evaporation method on soda lime glass (SLG) substrate under an electric field of 134 kV/m. The second step contains the oxidation process of the Zn layers under electric fields of 0, 48 and 84 kV/m in air. Then, samples were characterized by X-ray Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDX), Field Emission Scanning Electron Microscopy (FESEM), Raman and UV–Visible Spectroscopy. XRD study showed that all samples were crystallized in a hexagonal wurtzite crystal structure. EDX analysis showed that Zn and O atomic ratio, with a good approximation, are close to the ratio expected for ZnO (1:1). FESEM images illustrated that by applying the electric field, diameter of ZnO NRs decreased. Moreover, Raman spectra indicated a shift towards higher wavenumbers due to decreasing the crystallite size and vice versa. In addition, the results obtained from optical measurement demonstrated a reversed behavior of the samples' band gap energy with crystallite size.

Due to the recent advancements in machine vision, digital pathology has gained significant attention. Histopathology images are distinctly rich in visual information. The tissue glass slide images are utilized for disease diagnosis. Researchers study many methods to process histopathology images and facilitate fast and reliable diagnosis; therefore, the availability of high-quality slides becomes paramount. The quality of the images can be negatively affected when the glass slides are ink-marked by pathologists to delineate regions of interest. As an example, in one of the largest public histopathology datasets, The Cancer Genome Atlas (TCGA), approximately \(12\%\) of the digitized slides are affected by manual delineations through ink markings. To process these open-access slide images and other repositories for the design and validation of new methods, an algorithm to detect the marked regions of the images is essential to avoid confusing tissue pixels with ink-colored pixels for computer methods. In this study, we propose to segment the ink-marked areas of pathology patches through a deep network. A dataset from 79 whole slide images with 4, 305 patches was created and different networks were trained. Finally, the results showed an FPN model with the EffiecentNet-B3 as the backbone was found to be the superior configuration with an F1 score of \(94.53\%\).

Talbot effect in a metallic groove array is observed numerically based on finite element method (FEM) and verified theoretically based on non-paraxial approximation. Grooves in the metallic layer are separated from backside with a narrow gap that is smaller than surface plasmon (SP) penetration depth in metal. At certain circumstances, SPs tunnel through the gap and constructively interfere beneath the metallic layer. In propagation pattern, called Talbot carpet, self-images at certain distances in a periodic row parallel the metallic layer are formed. The distance, called Talbot distance, is coincident with non-paraxial approximation result. To evaluate the periodicity of revivals, new parameters such as R-square, contrast, and image size are introduced. Afterwards, influence of the structural parameters such as groove size, period, and gap thickness on the light intensity is analyzed and proper values for near-infrared wavelength range is determined. We anticipate that our finding reveals better understanding of SP tunneling and paves a way toward utilization of this effect in Talbot effect attributed applications, particularly image processing.

Advancements in processing techniques have facilitated the development of a series of unique high-performance DuPont™ Kevlar® fibers. Directly characterizing interior structures of these fibers is vital for connecting processing variations with resulting mechanical properties. Here we report detailed investigations of processing-internal structure-property relationships among four distinct classes of Kevlar® fibers (K119, K29, KM2+, and K49). We employ a novel focused ion beam (FIB) notch technique to obtain pristine interior fiber planes and measure morphology and transverse stiffness across these surfaces via multifrequency atomic force microscopy (AFM) maps. Combining these observations with tensile tests of single fibers drawn from the same tows, we acquire remarkable insights into structural motifs that strongly correlate with measured mechanical properties. Most notably, we uncover alternating stiffness bands that are especially apparent in low-modulus, non-heat-treated fibers, revealing a unique manifestation of internal structural variations that helps explain the observed trends in material response.

Tribenuron-methyl is commonly used for post emergence control of broad leaf weeds in wheat fields. In order to survey suspicious resistant weeds in wheat fields to this herbicide thirty-eight fields of Kermanshah province were investigated during 2012- 2013. Seeds of suspected resistance of wild mustard were gathered and tested in a randomized complete blocks design experiment with three replications. First, for early detection of herbicide resistance, the suspected population was screened using discriminating dose of tribenuron-methyl. Determining of the resistance degree was conducted by whole plant bioassay tests using dose-response curves. The resistance mechanisms were assayed by molecular methods, especially using the ALS gene cloning by PJET1.2/blunt Vector. For susceptible populations, the concentration required for complete control was 10.4 g ai ha-1 tribenuron-methyl. Also, in screening tests 50% of populations as resistant populations were identified. According to the Beckie and Tardif, it was found that 57.8% of these population did have a very high degree of resistance, 31.5% with high resistance and 10/5% with low resistance degree. GR50 of the resistant weeds was also increased as compared to sensitive weed, which indicates resistance in this province, Thus to control the resistant populations Z15, this amount increased to 1309 g ai ha-1.The results of DNA sequencing showed that mutation by replacing proline amino acid at position Ala122 causes resistance based on target-site mutation.

In this paper, two master and slave chaotic satellites will be synchronized acceptably using two different control methods. The first method is based on the neural networks in which two neural controllers called NARMA-L2 and Predictive controllers will be designed. In the second method a Nonlinear controller is designed by the Feedback linearization approach. The simulation results of the designed controllers have been compared with a performed control method called Active control to verify the effectiveness of the proposed controllers and to show the advantages and disadvantages of each one.

Feature vectors provided by pre-trained deep artificial neural networks have become a dominant source for image representation in recent literature. Their contribution to the performance of image analysis can be improved through finetuning. As an ultimate solution, one might even train a deep network from scratch with the domain-relevant images, a highly desirable option which is generally impeded in pathology by lack of labeled images and the computational expense. In this study, we propose a new network, namely KimiaNet, that employs the topology of the DenseNet with four dense blocks, fine-tuned and trained with histopathology images in different configurations. We used more than 240,000 image patches with 1000x1000 pixels acquired at 20x magnification through our proposed "highcellularity mosaic" approach to enable the usage of weak labels of 7,126 whole slide images of formalin-fixed paraffin-embedded human pathology samples publicly available through the The Cancer Genome Atlas (TCGA) repository. We tested KimiaNet using three public datasets, namely TCGA, endometrial cancer images, and colorectal cancer images by evaluating the performance of search and classification when corresponding features of different networks are used for image representation. As well, we designed and trained multiple convolutional batch-normalized ReLU (CBR) networks. The results show that KimiaNet provides superior results compared to the original DenseNet and smaller CBR networks when used as feature extractor to represent histopathology images.

A circular slit-groove surface plasmon polaritons (SPPs) launcher surrounding a photodetector is employed theoretically to enhance the photocurrent of atypical Si-Ge photodetectors. The slit and grooves are designed such that the SPPs are focused at the center of the absorption layer of the photodetector to result in additional electric current. Fabry–Perot resonance condition accurately calculates the period of the groove, slit-groove distance, photodetector radius, and slit-photodetector distance. The manipulation leads to constructive interference between the incident light impinging from the top and the SPPs propagating toward the photodetector. Simulation result shows that photocurrent increases by approximately 13-fold when the SPPs are introduced.

This chapter discusses various polymerization routes for major polyolefins such polyethylenes and polypropylene with emphasis on various catalysts. Ziegler–Natta catalysts as well as newer metallocene catalysts are reviewed. Major industrial polymerization processes are also discussed. This chapter finally describes the most important extrusion methods for polyolefins, which can create a variety of products from processes like melt spinning, film casting, film blowing, injection molding, blow molding, and rotational molding. Melt spinning of polyolefins is described in a great detail.

Background The goal of this research was to measure the age-sex standardized prevalence of pre-diabetes (pre-DM) and diabetes (DM), and the effectiveness of diabetes management (using HbA1C as the indicator) in an urban area in Iran. Methods Using a randomized cluster household survey, we recruited 5900 individuals whose age ranged from 15 to 75 from Kerman for assessing coronary artery disease risk factors (KERCADRS) including diabetes. In 2010 and 2011, all of the participants were interviewed by trained staff for medical history and physical activities, and were then examined for blood pressure and anthropometric measures. Venus blood sample was also collected for fasting plasma glucose and HbA1c. Results The age-sex standardized prevalence of pre-diabetes, diagnosed and undiagnosed was 18.7%, 6.3% and 2.7%, respectively. Diabetes increased by age (from 14.7% in the 15–24 years old group to 28.4% in the 65–75 years old group), particularly after 40 years. Occasional opium users had the highest prevalence of Pre-DM (34.6%). Seventy-nine percent of the depressed and 75.5% of the anxious participants with diagnosed-DM were identified as uncontrolled-DM. More than 60% of diagnosed diabetic cases had impaired HbA1c. Overweight and obesity (adjusted odds ratio (AOR) 1.6) and low physical activity (AOR 1.5) were the most preventable risk factors associated with diabetes. Conclusion Considerable prevalence of diabetes, susceptibility in progressing to diabetes and uncontrolled diabetes among individuals living in Kerman, suggested ineffective prevention and treatment of diabetes in urban areas in Iran. Successful experience regarding primary health-care in rural areas should be expanded to urban settings. 摘要 背景： 这项研究的目的是在伊朗市区调查经过年龄-性别标准化后的糖尿病前期（pre-DM）以及糖尿病（DM）的患病率，并且调查了糖尿病的治疗效果（用HbA1c作指标）。 方法： 使用随机聚类家庭调查法，我们招募了5900名来自克尔曼的受试者，他们的年龄为15至75岁，评估了包括糖尿病在内的冠心病危险因素（Kerman for assessing coronary artery disease risk factors，KERCADRS）。在2010与2011年，所有的参与者都由受过训练的医务人员来接诊，记录他们的医疗史以及体力活动情况，接着进行血压与人体测量学的检查。还要搜集静脉血样用来测定空腹血糖与HbA1c。 结果： 年龄-性别标准化后的糖尿病前期、已诊断的以及未诊断的糖尿病患病率分别为18.7%、6.3%与2.7%。糖尿病患病率随着年龄增长而增加（从15–24岁年龄组的14.7%至65-75岁年龄组的28.4%），特别是40岁以后。偶尔吸食鸦片的人群的Pre-DM患病率最高（34.6%）。在合并已诊断DM的患者中，79%的抑郁症以及75.5%的焦虑症参与者被判定为未控制的DM。60%以上的已诊断糖尿病病例的HbA1c异常。超重与肥胖（校正后的优势比[AOR]为1.6）以及低体力活动（AOR为1.5）是最有可能得到预防的糖尿病相关危险因素。 结论： 生活在克尔曼的人群的糖尿病患病率、容易进展为糖尿病以及未控制的糖尿病患病率相当高，这提示伊朗市区的糖尿病预防与治疗工作效果不佳。应该将农村地区有关初级卫生保健的成功经验扩展到城市环境中。

Objective Hyperglycemia in patients with Diabetic Mellitus (DM) results from the demolition of islet β cells in the pancreas as well as failure in insulin action or poor response to insulin secretion and there are no further methods to treat diabetes apart from insulin injection and oral hypoglycemic medicines. Thus, the main objective of the current research investigates hydro-alcoholic extracts of Prosopis farcta on impact on the Pyruvate kinase (Pk), Phospho fructo kinase (PFK), Gluco kinase (GK) and signaling insulin Phosphotidylinositol 3-Kinase (PI3K), Insulin Receptor Substrate (IRS1), Glucose Transporter type2 (GLUT2) in HepG2 cells. Method By various concentrations (0–10 mg/ml) of the extract (leaf-root – fruit) for 24 and 48 h, HepG2 cells were cultured and treated in this experimental research. MTT test evaluated cell proliferation by ELISA Reader measured the optical density of the colored solution at 570 nm wavelengths. Real-time-PCR method defined the fold changes of genes expression against β-actin. Data were analyzed by ANOVA. Variations with a P-value Results Our results showed cells were treated with various concentrations of extract (leaf-root – fruit) for 24 and 48 h had markedly declined cell viability in HepG2 cell line as compared to controls in a time and dose-dependent methods, an evident deviation is seen between different concentrations of the extracts. Real Time-PCR analysis showed that the expression of glucokinase, phosphofructo and pyruvate kinase were down regulated and expression of IRS1-PI3K-GLUT2 genes were up regulated in compare to control cells (P Conclusion It appears the anti-diabetic impact of the Prosopis farcta plant not to be over the glycolysis path. This acts mechanisms via enhancing the gene expression in the insulin signaling pathway. The plant, thus, may serve to enhance the insulin secretion function through triggering insulin signaling paths and, in turn, inhibiting increased blood glucose impact on diabetic patients. It is, therefore, expected that the various extracts of such plant may have an impact on diabetic patients, type-2 diabetes in particular.

A circular slit-groove surface plasmon polaritons (SPPs) launcher surrounding a photodetector is employed theoretically to enhance the photocurrent of a typical Si-Ge photodetectors operating at telecommunication frequency regime. The slit and grooves are designed such that the SPPs are focused at the center of the absorption layer of the photodetector to result in additional electric current. Phase difference approach is applied to lead constructive interference between the incident light impinging from the top and the SPPs propagating toward the photodetector. Simulation result proves the interference and periodic behavior is observed. Finally the period of the groove, slit-groove distance, and slitphotodetector distance is determined via simulation. Furthermore it was shown that photocurrent increases by approximately 13-fold when the SPPs are introduced.

Introduction: Care for a mentally retarded child induces a lot of problems for the mother and leads her to care giving strain and ignorning her self-care. Spiritual health will co-ordinate all aspects of human life and is necessary for coping with diseases in mother of mentally retarded children. Aim: To evaluate the effects of spiritual self-care training on care giving strain in mothers of mentally retarded children. Materials and Methods: The present study, is a before and after type quasi-experimental research based on which 60 mothers of mentally retarded children who were hospitalized in Elahi Rehabilitation Center in Quchan City, were selected using convenience sampling and were randomly assigned to intervention and control groups. Data was collected by demographic characteristic questionnaire and care giving strain questionnaire that were filled by groups before, immediately and two weeks after spiritual self-care training. Data was analysed using SPSS version 20. Results: According to the results, there was no significant difference between the mean score of care giving strain in intervention and control groups before and immediately after the intervention. However, among the members of the intervention group the score of mother care giving strain decreased an average of 87.21% within two weeks after the intervention, which was statistically significant over time (p=0.001). The score of mothers in the control group increased an average of 5% over time which was not statistically significant (p=0.4). The observed differences between these groups were also statistically significant even after controlling the effects of such intervening factors as marital status, children age and the years of caring for children (p=0.001). Conclusion: Spiritual self-care training can decrease care giving strain in mothers of mentally retarded children. Therefore, strengthening their spiritual beliefs and backgrounds, mothers can greatly reduce the strain caused by care giving problems of mentally retarded children.

In this study, we investigated the effect of tensile properties of poly(ethylene naphthalate) (PEN) yarns on the ballistic performance of woven and nonwoven soft and composite armors. The results of ballistic tests of PEN armors were compared with Kevlar 49 armors as a reference. Based on these results, the Cunniff's equation was revised by removing the fiber elongation at break to predict the relationship between tensile properties and ballistic performances of PEN fibers. The calculations showed that by increasing tenacity of PEN fibers from 8.5 g/den (commercial product) to 12.5 g/den (strongest up to date PEN fibers produced by a novel melt spinning process discovered by our research group), the weight ratio of PEN to Kevlar 49 decreased from 1.8 to 1.35 with the same ballistic performance. Contrary to the results of the soft armors, composite armors made of high modulus PEN woven fabric showed a 17% lower ballistic resistance compared to the composite armor made of low modulus PEN woven fabric. The results of ballistic tests indicated that high tenacity PEN fibers produced in this research could have potential in soft and composite armors, and high velocity impact applications or improve performance of PEN in its current applications. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

In this work, the effects of a phosphate containing stabilizer on the mechanical, morphological and thermal properties of a compatibilized high density polyethylene (HDPE)/ethylene vinyl acetate (EVA) blend containing an ammonium quaternary salts modified montmorillonite were studied from both statistical and experimental aspects. According to the results obtained from simultaneous implementation of analysis of variance (ANOVA) and mean effect assessment, the formulations designed based on the optimized coupling of stabilizer into organoclay/compatibilizer system exhibited the highest tensile properties among the prepared samples. From experimental point of view, the d -spacing measurements and microscopy observations through X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively, revealed that the stabilizer not only favored the penetration of the polymeric chains between the silicate layers but also contributed to provide finer dispersion of the minor phase in the matrix. Thermal characterizations using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed that the stabilizer could play a role in prevention of the organic modifier of the nanoclay to undergo thermo-oxidative degradation by hindering the SN 2 nucleophilic substitution reactions between alkyl ammonium chains and oxygen molecules. This, we believe, is responsible for the properties enhancement, since the protective role of stabilizer might inhibit the formation of destructive degradation products which could collapse the organoclay tactoids and also deactivate the anhydride groups of the compatibilizer.

Today's strict environmental laws pose significant challenges for coating's formulators to look for eco-friendly products. Powder coatings, particularly polyester/epoxy blends have demonstrated their ability as alternatives to traditional solvent-borne coatings. Recently, the use of nanoparticles such as nano-CaCO 3 (nCaCO 3 ) has been suggested as a beneficial strategy towards powder coating application with improved properties. Here, we study the effect of nCaCO 3 on morphology, cure behavior, adhesion and hardness of polyester/epoxy systems. The nanoparticles shape, size and dispersion state were investigated through X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) methods. Furthermore, isothermal cure characterization of the neat and filled systems was performed using a torque rheometer. The most important finding based on the rheological studies was the catalytic effect of nCaCO 3 on cure reaction of polyester/epoxy, leading to the shorter curing time. Moreover, the kinetic analyses of rheograms revealed a marked decrease in the activation energy of the cure process upon raising nCaCO 3 content. Interestingly, pull-off adhesion and hardness tests showed that the hardness and adhesion strength were dramatically increased by the addition of nCaCO 3 into the polyester/epoxy system compared to pure blend resin. Therefore, considering the strong competition in powder coating market, the use of nCaCO 3 as a commercial and inexpensive nanofiller is necessary not only to reduce the dwell time which has benefits in terms of the energy consumption and economics, but also to improve the performance of final polyester/epoxy coating.

In this work, the effect of quaternary ammonium salt containing nanoclay content (1–5 wt%) on phase morphology, rheology, cure kinetics, and mechanical properties of the vinyl ester resin (VER)-based nanocomposites was studied. The morphological characterization including d-spacing measurement, microscopy observation and phase-height image processing were performed on the prepared nanocomposites using small angel X-ray scattering (SAXS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). According to the results obtained from these techniques, it was concluded that an intercalated morphology existed for all the nanocomposites. The kinetic analyses of the isothermal curing followed by storage modulus obtained from the rheometry experiments are shown to be an affective rheological characteristic to investigate the cure behavior of VER/clay nanocomposites. In addition, the most important finding regarding the effect of nanoclay on the cross-linking behavior of VER systems lays on the chemisorption and physisorption of the reacting monomers and initiator molecules on the nanoclay platelets surface which is found to be responsible for the retardation of the cure reaction caused by organoclay. Eventually, the mechanical characterizations were performed through the tensile, flexural and impact analysis tests. In this case, a considerable improvement of the bulk mechanical responses such as tensile and flexural strengths and also the corresponding moduli were observed for the nanocomposites. Copyright © 2011 John Wiley & Sons, Ltd.

chinese acad sci, ningbo inst mat technol & engn, ningbo 315201, zhejiang, peoples r china.

Porous nylon-6 fibers are obtained from Lewis acid-base complexation of gallium trichloride (GaCl3) and nylon-6 using electrospinning followed by GaCl3 removal. DSC and FTIR results reveal that the electrospun fibers, prior to GaCl3 removal, are amorphous with no hydrogen bonds present between nylon-6 chains. GaCl3 being a Lewis acid interacts with the Lewis base sites (CdO groups) on the nylon-6 chains, thereby preventing the chains to crystallize via intermolecular hydrogen bonding. Subsequent removal of GaCl3 from the as-spun fibers by soaking the electrospun web in water for 24 h leads to the formation of pores throughout the fibers. While the average fiber diameter remains effectively the same after salt removal, the average surface area increases by more than a factor of 6 for the regenerated fibers. The dual use of a metal salt (Lewis acid) to (a) facilitate fiber formation by temporary removal of polymer interchain interactions and (b) act as a porogen provides a facile approach to obtain porous fibers via electrospinning.

This chapter covers recent developments in the production of well established high performance fibers such as Kevlar, PBO, Spectra and Dyneema fibers and depicts a new super strong M5. The latter fibers have the modulus of 330GPa and tenacity of 5GPa. DuPont de Nemours is currently developing commercial M5 fibers and yarns. A very interesting monomer namely, 2,5‐dihydroxyterephthalic is used for making poly{2,6‐diimidazo[4,5‐b:4′,5′‐e]pyridinylene‐1,4‐(2,5‐dihydroxy)phenylene} (PIPD). The unique feature of the polymer is that the two hydroxyl groups (on terephthalic acid) can form intermolecular hydrogen bonds and therefore fibrillation, that is often a problem for aramid fibers, is practically eliminated. As a result, M5 fibers have the highest compressive strength among synthetic fibers. Exploratory evaluation of the UV stability of M5 indicated excellent performance in that field. The mechanical properties of the new fiber make it competitive with carbon fiber in most applications ‐ in light, slender, ...

A nylon 6,6 complex with GaCl 3 in nitromethane (4–5 wt% nylon 6,6) was prepared at 50–70 °C over 24 h for the purpose of disrupting the interchain hydrogen bonding between nylon 6,6 chains, resulting in amorphous nylon 6,6, and increasing the draw ratio for improving the performance of nylon 6,6 fibers. After drawing, complexed films and fibers were soaked in water to remove GaCl 3 and regenerate pure nylon 6,6 films and fibers. FTIR, SEM, DSC, TGA, and mechanical properties were used for characterization of the regenerated nylon 6,6 films and fibers. The amorphous complexed nylon 6,6 can be stretched to high draw ratios at low strain rates, due to the absence of hydrogen bonding and crystallinity in these complexed samples. Draw ratios of 7–13 can be achieved for complexed fibers, under low strain rate stretching. This study indicates that nylon 6,6 fibers made from the GaCl 3 complexed state, using a high molecular weight polymer, can reach initial moduli up to 13 GPa, compared to initial moduli of 6 GPa for commercial nylon 6,6 fibers. Lewis acid–base complexation of polyamides provides a way to temporarily suppress hydrogen bonding, potentially increasing orientation while drawing, and following regeneration of hydrogen bonding in the drawn state, to impart higher performance to their fibers.

In the present study, the morphology and mechanical properties of nylon-6 nanofibers were investigated as a function of molecular weight (30,000, 50,000, and 63,000 g/mol) and electrospinning process conditions (solution concentration, voltage, tip-to-collector distance, and flow rate). Scanning electron micrographs (SEM) of nylon-6 nanofibers showed that the diameter of the electrospun fiber increased with increasing molecular weight and solution concentration. An increase in molecular weight increases the density of chain entanglements (in solution) at the same polymer concentration; hence, the minimum concentration to produce nanofibers was lower for the highest molecular weight nylon-6. The morphology of electrospun fibers also depended on tip-to-collector distance and applied voltage concentration of polymer solution as observed from the SEM images. Trends in fiber diameter and diameter distribution are discussed for each processing variable. Mechanical properties of electrospun nonwoven mats showed an increase in tensile strength and modulus as a function of increasing molecular weight. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008