EP Samples Research Articles

A Model for Determining the Effective Thermal Conductivity of Porous Heterogeneous Materials

In this study, an algebraic equation is shown for determining thermal conductivity coefficient of a porous heterogeneous solid material with two components. This equation was developed based on the porosity of the material, ratio, density and thermal conductivities of its components. This equation was applied to the waste EPS aggregate and samples with cement or gypsum mixed binders. Packaging waste EPSs were collected, decomposed to particles of 0–3 mm diameter and mixed with each binder volumetrically in the ratios of 20 %, 40 %, 60 % and 80 % separately. Thermal conductivity coefficient of the samples was determined by using the hot wire method. The calculated values were 4.41 % to 26.04 % higher than the measured values in the samples with cement, and they were 5.79 % to 15.62 % higher than the measured values in the samples with gypsum. The equation was applied similarly to the samples with expanded clay and cement with pumice aggregates.

Low content Ag-coated poly(acrylonitrile) microspheres and graphene for enhanced microwave absorption performance epoxy composites

Silver nanoparticles was uniformly anchored on the surface of hollow poly(acrylonitrile) microspheres with a facile chemical method using hydrazine hydrate as reductant. Integrating these conducting hollow spheres (PANS@Ag) with chemical reduced graphene oxide (RGO) dispersed in epoxy resin, a lightweight microwave absorber was successfully prepared with enhanced microwave absorption performance. The chemical constitution and surface morphology of as-synthesized RGO and PANS@Ag powders were characterized by XRD, XPS, FE-SEM and SAED, while the electromagnetic properties of these different proportion PANS@Ag-RGO/EP samples were analyzed through vector network analyzer (VNA). The minimum reflection loss (RL) could reach up to −28.1 dB at 8.8 GHz with a layer thickness of 2 mm, and the corresponding effective absorption bandwidth (RL values less than −10 dB) was from 7.9 GHz to 9.8 GHz. However, the dosage of PANS@Ag and RGO was merely 3 wt% and 1 wt%, respectively. As the content of PANS@Ag powders decreased to 1 wt%, the PANS@Ag-RGO/EP samples still retained effective microwave absorption performance and the optimal RL was −14.7 dB. The density of as-prepared absorbers was in the range of 0.49 ∼ 0.87 g cm−3. The low content, low density and enhanced microwave absorption performance endow the hybrid composites with competitive application prospect in stealth technology field.

F44. AN ADD-ON TRIAL WITH N-ACETYL-CYSTEINE (NAC) IN EARLY PSYCHOSIS PATIENTS: TOWARDS BIOMARKER GUIDED TREATMENT

BackgroundOxidative stress, coupled with dysregulation of inflammation, NMDAR and dopamine, is involved in schizophrenia (SZ) pathophysiology. Earlier add-on clinical trials showed in chronic SZ patients that NAC, a precursor of glutathione (GSH), an important cerebral antioxidant, improved negative symptoms, mismatch negativity and local synchronization. We hypothesized that NAC at an earlier stage of illness would have a greater impact.MethodsEarly psychosis patients (EP, less than 5 years of illness, N=63; NAC=32, placebo=31) were supplemented with NAC (2.7g/day, 6 months) in a double-blind randomized placebo-controlled trial. Outcome measures: PANSS and neurocognition (MATRICS Consensus Cognitive Battery; n=36); quantification of medial prefronfal cortex glutathione (GSHmPFC) by 1H-magnetic-resonance-spectroscopy, of white matter diffusion properties estimated by generalized fractional anisotropy (gFA) computed from diffusion spectrum imaging (DSI), of blood cells GSH (GSHBC) and GSH peroxidase activity (GPxBC) at start and end of trialResultsWhile PANSS negative and positive were not affected by NAC, NAC improved Processing Speed (NAC > Placebo; F(1, 30)=5.849, p=.022), favoring 2 of 3 processing speed tasks (Trail Making A, F(1, 30)=4.279, p=.048 & Verbal Fluency, F(1, 30)=5.749, p=.023). GSHmPFC (+23%, p=0.005) and GSHBC (+19%, p=0.05) were increased following NAC treatment. In patients with high-baseline GPxBC (>22.3U/gHb), subgroup explorations revealed an improvement of PANSS positive compared to placebo (p=0.02). The change of PANSS positive correlated negatively with that of GPxBC activity, showing that the improvement paralleled the restoration of redox status. NAC group showed 11% increase in fornix white matter integrity as measured by gFA, correlating with an increase in GSHmPFC over the 6-months period.DiscussionThis is the first clinical trial assessing the impact of NAC treatment in a sample of EP and the potential predictive role of peripheral biomarkers of redox dysregulation. The hypothesis that NAC would be beneficial to negative symptoms in EP was not confirmed in this small sample, most likely in reason of their very low level at baseline. The NAC induced GSHmPFC increase demonstrates its target engagement. NAC improved Processing Speed showing a therapeutic enhancement of cognitive functions. Most importantly, NAC improved fornix integrity, in association with brain GSH elevation, demonstrating for the first time that a redox regulator can enhance structural connectivity. Peripheral redox status allows identifying a subgroup of patients with improved positive symptoms. Future biomarker guided antioxidant interventions in larger EP samples should replicate these findings.

Synthesis of a phosphorus–nitrogen-containing flame retardant and its application in epoxy resin

In this article, a phosphorus–nitrogen-containing flame retardant (DOPO-T) was successfully synthesized by nucleophilic substitution reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and cyanuric chloride. The chemical structure of DOPO-T was characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance (NMR) and phosphorous-31 NMR, and elemental analysis. DOPO-T was then blended with diglycidyl ether of bisphenol-A to prepare flame-retardant epoxy resins. Thermal properties, flame retardancy, and combustion behavior of the cured epoxy resins were evaluated by differential scanning calorimetry, thermogravimetric analysis, limited oxygen index (LOI) measurement, UL94 vertical burning test, and cone calorimeter test. The results indicated that the glass transition temperature ( Tg) and temperature at 5% weight loss of epoxy resin (EP)/DOPO-T thermosets were gradually decreased with the increasing content of DOPO-T. DOPO-T catalyzed the decomposition of EP matrix in advance. The flame-retardant performance of EP thermosets was significantly enhanced with the addition of DOPO-T. EP/DOPO-T-0.9 sample had an LOI value of 36.2% and achieved UL94 V-1 rating. In addition, the average of heat release rate, peak of heat release rate, average of effective heat of combustion, and total heat release (THR) of EP/DOPO-T-0.9 sample were decreased by 32%, 48%, 23%, and 31%, respectively, compared with the neat EP sample. Impressively, EP/DOPO-T thermosets acquired excellent flame retardancy under low loading of flame retardant.

Mechanical Properties of Alumina Nanofilled Polymeric Composites Cured with DDSA and MNA

Reinforced concrete is widely used in structures. New materials to replace both the steel and the concrete have been studied in many research centres. One of the possibilities for the reinforcement is the partial or total replacement of the steel bars by new composite materials. Nano composites are very promising, and an investigation line was developed to this end by an interdisciplinary team. On this work, the mechanical properties of epoxy resin nanocomposites (EPNCs) filled with α-Al2O3 nanoparticles (NPs) with irregular shape and approximately 100 nm maximum diameter size was investigated. The variable study was the alumina NPs contents: 1, 3 and 5 wt.%. The NPs were previously pretreated with a silane agent (APTES). Two hardeners, 3-dodec-2-enyloxolane-2,5-dione (DDSA) and 8-methyl-3a,4,7,7a-tetrahydro-4,7-methano-2-benzofuran-1,3-dione (MNA), frequently used in epoxy resin embedding tissues, were used simultaneously for this study. Unlike other hardeners, DDSA does not need curing treatment, constituting a novel application and a saving time-energy during the manufacturing process. Considering the mechanical behaviour, it was observed that the EPNCs filled with 5 wt.% of alumina NPs showed the maximum improvement in flexural modulus, around 14 % when compared to the pristine EP sample. No relevant effect was observed on the flexural strength by adding alumina NPs. Additionally, the maximum increase observed for hardness, and Young’s modulus were about 13 % and 28 %, respectively (the maximum increase was observed at 3 wt.%).

Deposition of SiCxHyOz thin film on epoxy resin by nanosecond pulsed APPJ for improving the surface insulating performance

Non-thermal plasma surface modification for epoxy resin (EP) to improve the insulation properties has wide application prospects in gas insulated switchgear and gas insulated transmission line. In this paper, a pulsed Ar dual dielectrics atmospheric-pressure plasma jet (APPJ) was used for SiCxHyOz thin film deposition on EP samples. The film deposition was optimized by varying the treatment time while other parameters were kept at constants (treatment distance: 10 mm, precursor flow rate: 0.6 l min−1, maximum instantaneous power: 3.08 kW and single pulse energy: 0.18 mJ). It was found that the maximum value of flashover voltages for negative and positive voltage were improved by 18% and 13% when the deposition time was 3 min, respectively. The flashover voltage reduced as treatment time increased. Moreover, all the surface conductivity, surface charge dissipation rate and surface trap level distribution reached an optimal value when thin film deposition time was 3 min. Other measurements, such as atomic force microscopy and scanning electron microscope for EP surface morphology, Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy for EP surface compositions, optical emission spectra for APPJ deposition process were carried out to better understand the deposition processes and mechanisms. The results indicated that the original organic groups (C–H, C–C, C=O, C=C) were gradually replaced by the Si containing inorganic groups (Si–O–Si and Si–OH). The reduction of C=O in ester group and C=C in p-substituted benzene of the EP samples might be responsible for shallowing the trap level and then enhancing the flashover voltage. However, when the plasma treatment time was longer than 3 min, the significant increase of the surface roughness might increase the trap level depth and then deteriorate the flashover performance.

Preparation and investigation of flame‐retardant epoxy resin modified with a novel halogen‐free flame retardant containing phosphaphenanthrene, triazine‐trione, and organoboron units

ABSTRACTIn this article, a novel flame retardant (coded as BNP) was successfully synthesized through the addition reaction between triglycidyl isocyanurate, 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide and phenylboronic acid. BNP was blended with diglycidyl ether of bisphenol‐A to prepare flame‐retardant epoxy resin (EP). Thermal properties, flame retardancy, and combustion behavior of the cured EP were studied by thermogravimetric analysis, limited oxygen index (LOI) measurement, UL94 vertical burning test, and cone calorimeter test. The results indicated that the flame retardancy and smoke suppressing properties of EP/BNP thermosets were significantly enhanced. The LOI value of EP/BNP‐3 thermoset was increased to 32.5% and the sample achieved UL94 V‐0 rating. Compared with the neat EP sample, the peak of heat release rate, average of heat release rate, total heat release, and total smoke production of EP/BNP thermosets were decreased by 58.2%–66.9%, 27.1%–37.9%, 25.8%–41.8%, and 21.3%–41.7%, respectively. The char yields of EP/BNP thermosets were increased by 46.8%–88.4%. The BNP decomposed to produce free radicals with quenching effect and enhanced the charring ability of EP matrix. The multifunctional groups of BNP with flame retardant effects in both gaseous and condensed phases were responsible for the excellent flame retardancy of the EP/BNP thermosets. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45291.

Surface modification of epoxy resin using He/CF4 atmospheric pressure plasma jet for flashover withstanding characteristics improvement in vacuum

For enhancing the surface electric withstanding strength of insulating materials, epoxy resin (EP) samples are treated by atmospheric pressure plasma jet (APPJ) with different time interval from 0 to 300s. Helium (He) and tetrafluoromethane (CF4) mixtures are used as working gases with the concentration of CF4 ranging 0%-5%, and when CF4 is ∼3%, the APPJ exhibits an optimal steady state. The flashover withstanding characteristics of modified EP in vacuum are greatly improved under appropriate APPJ treatment conditions. The surface properties of EP samples are evaluated by surface roughness, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle. It is considered that both physical and chemical effects lead to the enhancement of flashover strength. The physical effect is reflected in the increase of surface roughness, while the chemical effect is reflected in the graft of fluorine groups.

The characterization of DOPO/MMT nanocompound and its effect on flame retardancy of epoxy resin

A DOPO-MMT nanocompound has been prepared and used to flame-retard epoxy resin (EP) compared with the physical mixture of DOPO and MMT. The structures of nanocompound and EP samples have been characterized by FTIR, XRD, SEM and TEM. Intercalated and exfoliation of MMT layers in DOPO and EP matrix have been observed which means good dispersity. The flame retardancy of EPs has been studied by limiting oxygen index measurements, UL-94 testing, and cone calorimeter test. The DOPO-MMT nanocompound shows better flame retardancy (limiting oxygen index, UL-94, peak of heat release rate, etc.) than the physical mixture of DOPO and MMT. The morphologies of EPs and chars after cone calorimeter test have been studied by SEM. Lighter color and better transparency of EP samples, smoother and less porous structure of chars both prove the DOPO-MMT nanocompound shows better flame retardancy because of the better dispersity of MMT layers in EP matrix.

Bisphenol-S bridged penta(anilino)cyclotriphosphazene and its application in epoxy resins: Synthesis, thermal degradation, and flame retardancy

A novel bridged-cyclotriphosphazene flame retardant, named bisphenol-S bridged penta(anilino)cyclotriphosphazene (BPS-BPP), was synthesized and characterized by fourier transform infrared (FTIR), 1H NMR and 31P NMR and mass spectroscopy (MS). Then, BPS-BPP was used to flame retard epoxy resin (EP, diglycidyl ether of bisphenol-A type). The curing behavior and glass-transition temperature (Tg) of EP/BPS-BPP were investigated by differential scanning calorimetry (DSC). The thermogravimetric analysis (TGA) results showed that the incorporation of BPS-BPP improved the thermal stability of EP at high temperature region. Limiting oxygen index (LOI) value of EP sample increased to 29.7% with limited amount of 9 wt% BPS-BPP. The peak of heat release rate (PHRR), total heat release (THR), total smoke production (TSP) values of the same sample, obtained from cone calorimetry, were declined conspicuously, indicating good flame-retardant and smoke suppression efficiency of BPS-BPP. The flame-retardant mechanism of EP/BPS-BPP thermosets was investigated via analyses of gaseous products and char residues. Based on the aforementioned studies, BPS-BPP was demonstrated as an effective flame retardant for EP due to temperature-dependent and bi-phase flame retardant mechanism.

Synthesis of a novel phosphorus-nitrogen type flame retardant composed of maleimide, triazine-trione, and phosphaphenanthrene and its flame retardant effect on epoxy resin

In this paper, a novel phosphorus/nitrogen-containing compound (DMT) constructed by maleimide, phosphaphenanthrene and triazine-trione was successfully synthesized. The chemical structure of DMT was characterized by Fourier transform infrared spectroscopy (FTIR), 1H and 31P nuclear magnetic resonance (NMR). DMT was then blended with diglycidyl ether of bisphenol-A (DGEBA) to prepare a series of flame-retardant epoxy resins. The flame retardancy and combustion behavior were evaluated using limited oxygen index (LOI), vertical burning (UL94) and cone calorimeter test. The results indicated that DMT dramatically enhanced the flame retardancy of epoxy resin. When the phosphorus content was only 1.0%, the EP/DMT-1.0 sample had a LOI value of 35.8%, and achieved UL94 V-0 rating. The combustion parameters disclosed that DMT obviously weakened the heat release intensity. Compared with the neat EP sample, the peak of heat release rate (pk-HRR), average of heat release rate (av-HRR) and total heat release (THR) of EP/DMT-1.25 sample were decreased by 59.4%, 28.2% and 27.4%, respectively. The decreased av-EHC of EP/DMT thermosets indicated that DMT inhibited the gaseous phase combustion due to the gaseous phase quenching effect of phosphorus-containing free radicals derived from the decomposed DOPO group. The condensed phase studies indicated that DMT promoted the charring of EP matrix and formation of phosphorus-containing char layer with compact and intumescent structure. DMT exerted bi-phase flame retardant effect.

Abstract 2781: Novel putative diagnostic methylation biomarkers for prostate cancer identified by whole genome DNA methylation profiling

Abstract BACKGROUND Aberrant patterns of DNA methylation is a typical hallmark of cancer. Several studies have reported DNA hypermethylation of a significant number of genes in various malignancies. This suggests a role of hypermethylation in the initiation and progression of cancer. In this study, we investigated genome-wide alterations in DNA methylation in prostate cancer (PCa). We compared alterations between tumor (Tu) and adjacent epithelial (Ep) tissues in order to identify hypermethylated genes in promoter regions associated with initiation and progression of prostate cancer. METHODS The study included 33 tumor samples including 21 paired Tu and Ep samples from 21 radical prostatectomy patients. Genomic DNA was isolated from FFPE tissue blocks. Genome-wide DNA methylation profiling was performed using the Infinium Illumina 450K array. A mixed linear model, with a random effect for patient, main effect of tissue, and covariate of array batch, was employed to identify probes that differed in methylation between tissue types. Multiple comparison adjustment was performed using the FDR (false discovery rate) method. RESULTS In total, 8791 hypermethylated CpG sites in the promoter regions were identified in Tu versus Ep tissue with FDR adjusted P <0.05. Hypermethylation status of our top-ranked hypermethylated genes (with an estimated mean absolute difference 0.3 or greater) between tumor and epithelial tissue was also observed in publicly available methylation data in PCa. To find out if promoter hypermethylation was associated with the regulation of gene expression, we analyzed gene expression of the 20 top-ranked hypermethylated genes using publicly available mRNA expression data in PCa. Several genes exhibited reduced expression in PCa samples. Similar observation was also noted in in vitro studies as significant (P <0.05) increase in gene expression following 5-Azacytidine treatment was detected only in PCa cell lines but not in normal prostate cell line. CONCLUSIONS This study identified promoter hypermethylation of several genes in PCa. These newly identified hypermethylated genes are potential biomarker candidates for PCa diagnosis. Currently we are evaluating the functional significance of these hypermethylated genes in prostate cancer. This work was supported by R01CA108633 (To AC), 1RC2CA148190 (To AC) U10CA180850-01 (To AC), 1R01CA169368 (To AC) from the National Cancer Institute (NCI), Brain Tumor Funders Collaborative Grant (To AC), Ohio State University Comprehensive Cancer Center Award (To AC). Citation Format: Arup Ratan Chakraborty, Erica Hlavin Bell, Simon Kriste, Vanessa Drendel, Joseph McElRoy, Martin Werner, Anca Grosu, Arnab Chakravarti. Novel putative diagnostic methylation biomarkers for prostate cancer identified by whole genome DNA methylation profiling. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2781.

Polyethyleneimine modified ammonium polyphosphate toward polyamine-hardener for epoxy resin: Thermal stability, flame retardance and smoke suppression

To expand the application of ammonium polyphosphate (APP) in epoxy resin (EP), hyperbranched polyethyleneimines (PEI) were selected to modify it via cation exchange reaction. Then, a highly-efficient flame-retardant hardener with poly-functionalities for EP was successfully prepared and named as PEI-APP. After curing, PEI-APP endowed the EP samples with good flame retardance and smoke suppression performance. Results suggested the total heat release (THR) and total smoke production (TSP) decreased 76.1% and 70.5% respectively. Thermogravimetric analyses (TGA) of the PEI-APP cured EPs displayed a slight improvement in the high temperature region compared with the reference sample (PEI/EP). Dynamic mechanical analysis (DMA) demonstrated that the glass transition temperature (Tg) of PEI-APP/EP also slightly increased compared with PEI/EP. Fourier transform infrared spectra (FTIR) was used to analyse the condensed products of PEI-APP/EP samples at different temperatures to investigate the flame-retardant mechanism. All the aforementioned results distinctly confirmed that PEI-APP did not only act as an effective flame-retardant hardener for EP, but also brought a good thermal stability and improved the smoke suppression to the system. This polyamine hardener provided a new platform for intumescent flame-retardant application in EP.

Tablet Longqing with or without levofloxacin for the treatment of IIIA chronic prostatitis

Objective To investigate the safety and efficacy of Tab Longqing and levefloxacin alone or combined to treat ⅢA prostatitis. Methods Between June 2012 and July 2013, a randomized, parallel, double blind with dummy, positive and placebo controlled multi-center clinical trial was designed. 337 patients were enrolled in this study. All of them were diagnosed as ⅢA prostatitis. And the NIH-CPSI scores showed moderate to severe degree in all cases. The EPS or urine post EPS samples showed the number of WBCs were more than 10/hp. No additional medications were given to those patients before initiating the study. Patients were randomized to 4 groups with 1∶1∶1∶1 ratio, including Tab Longqing group (group Q, Tab Longqing with dummy levofloxacin; n=84); Combined group (group C, Tab Longqing combined with Tab levofloxacin; n=84); Tab levofloxacin group(group L, levofloxacin with dummy Longqing; n=85) and placebo controlled group(group P, both dummy; n=84). There was no significant differences of patients' characters among those groups(P>0.05). NIH-CPSI pain score were measured pretreatment, 4 weeks or 8 weeks post-treatment. The WBCs in EPS or urine post EPS samples were also evaluated at the same time point. Results 337 patients were enrolled in the study with 273 cases into Per-protocol set, including 69 cases in group Q, 67 cases in group C, 68 cases in group L and 69 cases in group P. Before study, the baseline of pain scores was 11.04±2.95, 10.81±2.67, 9.66±2.51, 9.49±2.76 in each group, which didn't show the statistical difference (P<0.05). Four weeks after the study, the pain score was 6.52±2.68, 5.88±2.91, 7.22±2.86 and 7.14±3.03 in every group. It seemed that the Tab Longqing group and the combined group were better than the levofloxacin group and placebo group(P<0.05). There is no difference between Tab Longqing group and the combined group, or between levofloxacin group and placebo group. Eight weeks after the study, the pain score was 3.99±2.30, 4.61±2.33, 6.13±3.27 and 6.51±2.81 in every group, which were better than those at four weeks. The statistical results were similar to those at four weeks. However, Tab Longqing group seemed to be superior to other group. Conclusions To ⅢA prostatitis, Tab Longqing alone is efficacy and safe, which need not to be combined with levofloxacin. Key words: Prostatitis, chronic; Clinical trial; Tablet Longqing; Levofloxacin

Synthesis of a phosphorus/nitrogen-containing compound based on maleimide and cyclotriphosphazene and its flame-retardant mechanism on epoxy resin

In this paper, hexa(4-maleimido-phenoxyl)-cyclotriphosphazene (HMCP) was successfully synthesized by nucleophilic substitution reaction between N-(4-hydroxyphenyl) maleimide (HPM) and hexachlorocyclotriphosphazene (HCCP). The chemical structure of HMCP was characterized by Fourier transform infrared spectroscopy (FTIR), 1H and 31P nuclear magnetic resonance (NMR) and elemental analysis (EA). HMCP was then blended with diglycidyl ether of bisphenol-A (DGEBA) to prepare flame retardant epoxy resins. The flame-retardant properties of the epoxy resins were evaluated using limited oxygen index (LOI) measurement, UL94 test and cone calorimeter test. The fire properties indicated that HMCP exhibited high flame-retardant efficiency on the epoxy resin loaded with low phosphorus content. For example, the EP/HMCP-1.25 sample had a LOI value of 36.5%, and achieved UL94 V-0 rating. Compared with the neat EP sample, the peak of heat release rate (pk-HRR) and average of heat release rate (av-HRR) of the EP/HMCP-1.25 sample were decreased by 71% and 32.2%, respectively. The flame-retardant effect of HMCP in condensed and gaseous phase was studied respectively using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), TGA, chemical composition and morphology analysis of the char residues. HMCP decomposed to form phosphorus-containing compounds which promoted the carbonization of EP matrix in condensed phase, and release PO2 and phenoxyl free radicals with quenching effect to gaseous phase. The char layers with high oxidation resistance exhibited intumescent structures with more sealed surfaces, which served as protective char layers. The combined action of barrier effect and quenching effect endowed epoxy resin with excellent flame retardancy.

Testing of Energy Absorption Capability of Sandwich Structures Based on Metal Foams for Design of Protective Helmets

Purpose of this study is investigation of energy absorption capability of the sandwich structures composed of combination of polystyrene and metal foam element and their suitability as new structure for design of protective helmets. Two types of the metal foams were experimentally tested and evaluated: Alporas (Shinko Wire Ltd., Japan) and Aluhab (Aluinvent Plc., Hungary). Samples of the sandwich structure are composed of two layers: bottom expanded polystyrene (EPS 200S) layer and upper metal foam layer which are glued together. Prepared samples are tested using a drop tower experiment to measure sample response (acceleration, reaction force) at different strain rates and energies. From acceleration/time history the Head Injury Criterion (HIC) is calculated as significant parameters in terms of protective helmets. Moreover, measured and derived characteristics are compared with pure EPS samples to obtain comparison of deformation behaviour between conventional structure for protective helmets and designed sandwich structures.

Characteristics of urethral and epididymal semen collected from domestic cats—A retrospective study of 214 cases

This study was designed to describe and compare basic semen characteristics and sperm motility parameters obtained via computer-assisted sperm analysis (CASA) in feline semen collected from the urethra and epididymis, on the basis of large, unselected population of domestic cats. The semen collected from 214 males was subjected for routine semen assessment and CASA evaluation. Semen collected by urethral catheterization (CT) and by epididymal slicing (EP) has comparable characteristics according to total sperm count (47.7 ± 42.1 and 52.9 ± 45.0), subjective motility (71.1 ± 17.0 and 69.3 ± 13.9), viability (74.9 ± 13.4 and 76.7 ± 10.6), and morphology (52.6 ± 19.0 and 47.2 ± 17.4). The study of a large feline population confirmed a high incidence of teratospermy in cats, which negatively affects sperm motility parameters assessed by CASA. A lack of a correlation between CT and EP semen for total sperm count and viability, as well as occasional gross differences between the morphology of CT and EP semen of the same cat suggests that many factors may affect sperm cells, and the fertility and/or infertility of patients should not be assessed after examining only one sample. Additionally, technical problems with assessment of EP samples (understated results) suggest that CT semen is more appropriate for an analysis by CASA than EP.

Influence of electrolessly silver-plated multi-walled carbon nanotubes on thermal conductivity of epoxy matrix nanocomposites

In this work, multi-walled carbon nanotubes (MWCNTs) were electrolessly Ag-plated in order to investigate the effect of plating time on the thermal conductivity of Ag-plated MWCNTs-reinforced epoxy matrix composites. MWCNT surfaces were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS). The thermal conductivity of Ag-plated MWCNT-reinforced epoxy nanocomposites was measured using the thermal equilibrium method with ASTM D5470. From the results, it was found that the thermal conductivity of the composites enhanced with increasing plating time. In particular the Ag-10/EP sample showed more than 150% enhancement of the thermal conductivity compared to the as-received CNTs/EP sample. These results were attributed to the high contents of Ag particles and the increase of the interfacial adhesion between the Ag-CNTs and EP matrix in the composites.

Effect of curing on activation energy and dielectric properties of carbon black–epoxy composites at different temperatures

The effect of curing on activation energy and dielectric properties of carbon black–epoxy (CB–EP) composites has been reported at different temperatures and frequencies. The activation energy was found to be higher for the room temperature cured CB–EP samples as compared with the thermally cured CB–EP samples. Curing behavior of epoxy nanocomposites prove that epoxide molecules contribute to the curing reaction and reacted with them to form a cross-linked network. Dielectric constants of thermally cured CB–EP samples were higher than the room temperature cured samples. The results showed that activation energy, decreased with an increase in the concentration of carbon black in the composite, which may be due to an increase of polarization energy and/or charge carrier density leading to a decrease of the domain boundary potential of carbon black aggregates into the epoxy matrix. At room temperature, the electrical conductivity is due to electron tunneling and hopping. Dielectric constant of the CB–EP composite increase with increase in temperature and decreases with an increase in frequency from 0.5kHz to 10kHz for both room temperature cured and thermally cured specimens. The peak height of the dielectric constant curve of both cured samples decreases with increasing frequency.

Flame retardancy and thermal degradation behaviors of epoxy resins containing bisphenol a bis (diphenyl phosphate) oligomer

AbstractBisphenol A bis(diphenyl phosphate) oligomer (BBO) as flame retardant was synthesized, whose structure was characterized by IR and NMR. In all, 20% weight mixture polyphosphoric acid (APP) and BBO was doped into epoxy resins (EPs) to get 26.0% of limiting oxygen index and UL 94 V‐0. The degradation behavior of EP‐containing BBO/APP was studied by thermogravimetry, differential thermogravimetry, scanning electron microscopy, and cone calorimeter. The activation energies for the decomposition of EP samples are obtained using the method of Kissinger. The experimental results exhibited that for EP‐containing BBO/APP, compared with EP, initial decomposition temperature, maximum temperature at the peak position (Tm), and the activation energy for the decomposition are decreased, whereas the maximum weight loss rate (Rmax), char yields, and the inherent thermal stability are increased. Meanwhile, heat release, smoke production, and CO yield and CO2 yield of EP‐containing BBO/APP are much decreased compared with those of EP. The thermal degradation mechanism of EP‐containing BBO/APP has been proposed. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers