Synthesis and characterization of completely soluble and highly thermally stable PANI-DBSA salts

This paper presents synthesis and characterization of soluble polyaniline-dodecylbenzenesulfonic acid (PANI-DBSA) via inverse polymerization. A mixture of chloroform and 2-butanol was used as dispersion medium for the first time. This polymerization pathway leads to the formation of PANI-DBSA salts which are completely soluble in a number of common organic solvents (such as DMSO, DMF, chloroform and in a mixture of toluene) and 2-propanol (so far highest number of solvents for solubility of PANI). The influence of synthesis parameters such as concentration of aniline, benzoyl peroxide and dodecylbenzenesulfonic acid (DBSA) on the yield and other properties of the resulting PANI-DBSA salts was studied. Further characterization of the synthesized materials was done with the help of viscosity measurements, UV–Vis spectroscopy, cyclic voltammetry, XRD and SEM. TGA was used to analyze the thermal properties of synthesized polymer. The synthesized salts were found to be highly stable.     

Prandtl number effect on cooling performance of a heated cylinder in an enclosure filled with nanofluid

Natural convection heat transfer from a heated cylinder contained in a square enclosure filled with water–Cu nanofluid is investigated numerically. The main objective of this study is to explore the influence of pertinent parameters such as Prandtl number (Pr) and diameter (D) of the heated body on the flow and heat transfer performance of nanofluids while Rayleigh number (Ra) and the solid particle volume fraction (?) of nanoparticle are considered fixed. The results obtained from finite element method clearly indicate that heat transfer augmentation is possible using highly viscous nanofluid resulting in the compactness of many industrial devices.     

The NIP Genes in Sugar Beet: Underlying Roles in Silicon Uptake and Growth Improvement

Silicon - Silicon (Si) can stimulate plant growth and stress resistance. This study aimed at elucidating the physiological responses and molecular characterization of different NIP (nodulin 26-like...     

Thermal conductivity variation on natural convection flow of water–alumina nanofluid in an annulus

This work is focused on the numerical modeling of steady laminar natural convection flow in an annulus filled with water–alumina nanofluid. The inner surface of the annulus is heated uniformly by a uniform heat flux q and the outer boundary is kept at a constant temperature T_c. Two thermal conductivity models namely, the Chon et al. model and the Maxwell Garnett model, are used to evaluate the heat transfer enhancement in the annulus. The governing equations are solved numerically subject to appropriate boundary conditions by a penalty finite-element method. A parametric study is conducted and a selective set of graphical results is presented and discussed to illustrate the effects of the presence of nanoparticles, the Prandtl number and the Grashof number on the flow and heat transfer characteristics for both nanofluid models. It is found that significant heat transfer enhancement can be obtained due to the presence of nanoparticles and that this is accentuated by increasing the nanoparticles volume fraction and Prandtl number at moderate and large Grashof number using both models. However, for the Chon et al. model the greatest heat transfer rate is obtained.     

Child's gender and household food insecurity are associated with stunting among young Pakistani children residing in urban squatter settlements

BACKGROUND: The nutritional status of children is a good indicator of the overall well-being of a society and reflects food security as well as existing health-care and environmental conditions. In Pakistan, it is estimated that nearly 40% to 50% of children under the age of five are stunted. Due to greater economic opportunities available to the urban population as compared to the rural, it was believed that economic resources existed in poor urban Pakistani households but that the households lacked the skills and knowledge to translate their resources into good care and feeding practices. OBJECTIVE: This study aimed 1) to assess the prevalent care and feeding practices among children aged 6 to 18 months residing in the squatter settlements of Karachi and 2) to identify care and feeding practices, as well as any other underlying factors, associated with stunting. METHODS: A cross-sectional survey was conducted in eight settlements between October and December 2000. A total of 433 mothers of eligible children were interviewed with the use of structured questionnaires. Final analysis using multiple logistic regression was conducted on 399 mother-child pairs. RESULTS: Female children were nearly three times more likely to be stunted than male children. Households that were food insecure with hunger were also three times more likely than other households to have a stunted child. Lack of maternal formal schooling (adjusted prevalence odds ratio, 2.9; 95% confidence interval, 1.4 to 3.8) and large household size (adjusted prevalence odds ratio, 1.7; 95% confidence interval, 1.0 to 3.8) were also associated with stunting. Even though certain care and feeding practices were significant at the univariate level, they were not significant in the final multivariate analysis and so were excluded from the final model. CONCLUSIONS: In households where food insecurity exists, knowledge of care practices may not be sufficient, and interventions such as food subsidies must precede or accompany educational efforts. Further follow-up is required to explore the effect of gender differences on child care.     

Sensory and quality parameters of raw and processed Chicory-Hindbeh,a commonly consumed dark leafy green in Lebanon (Cichorium intybus L.) during frozen storage

This work aimed at assessing the effect of heat treatment and frozen storage on the sensory and chemical properties of chicory with the goal of optimizing the heat pretreatment-storage condition to best preserve the chemical and sensory properties of chicory. Raw, boiled (10 min), blanched (90 °C for 60 s) and steamed (for 20 s) chicory samples were produced and stored at −6 °C, −12 °C or −18 °C for 4 months. Chemical analyses (moisture, ash, vitamin C, peroxidase activity, chlorophyll and color) and sensory evaluation (QDA and hedonic evaluation) were conducted. Treatment significantly influenced all chemical variables (p < 0.001), except for moisture; and so did freezing temperatures for a-value (p < 0.001), chlorophyll-a, peroxidase activity, vitamin C and ash (p < 0.01), total chlorophyll, moisture and b-value (p < 0.05). Differences were obtained for age for all chemical variables (p < 0.001). Treatments affected consumers' acceptability of chicory and QDA showed that boiled chicory was significantly more tender, less chewy and crunchy and needed less time to disintegrate than other samples. PCA showed that PC1 and PC2 separated attributes based on type and intensity of treatments, respectively. It is recommended to use blanching at 90 °C for 60 s and freezing at −12 °C or −18 °C to best preserve the quality of chicory.     

Low‐temperature synthesis of nanocrystalline hydroxyapatite: Effect of Mg and Sr content

Nanocrystalline Mg‐ or Sr‐containing hydroxyapatite powders were synthesized through low‐temperature chemical precipitation. The most significant factor for reduction in particle sizes included adjusting the reaction temperature between 0°C and 50°C. Syntheses products were characterized using several analytical tools to determine purity and influence of added amount (up to 15 mol%) of Mg or Sr on the composition and structure. Qualitative analysis by Fourier transform infrared spectroscopy and low intensity, broad X‐ray diffraction peaks indicated the presence of nanocrystalline and/or amorphous hydroxyapatite in all the products. Moreover, a significant decrease in the crystallinity was observed with increasing Mg (up to 2.8 ± 0.3 wt%) and Sr (up to 9.6 ± 1.0 wt%) concentration. N₂ adsorption and scanning electron microscopy characterizations confirmed the nanocrystalline nature of the synthesized products. The synthesized products had nanosized spherical‐like particle morphology with the specific surface area ranging from 89 ± 7 to 150 ± 20 m²/g.     

Engagement Detection Based on Analyzing Micro Body Gestures Using 3D CNN

This paper proposes a novel, efficient and affordable approach to detect the students’ engagement levels in an e-learning environment by using webcams. Our method analyzes spatiotemporal features of e-learners’ micro body gestures, which will be mapped to emotions and appropriate engagement states. The proposed engagement detection model uses a three-dimensional convolutional neural network to analyze both temporal and spatial information across video frames. We follow a transfer learning approach by using the C3D model that was trained on the Sports-1M dataset. The adopted C3D model was used based on two different approaches; as a feature extractor with linear classifiers and a classifier after applying fine-tuning to the pre-trained model. Our model was tested and its performance was evaluated and compared to the existing models. It proved its effectiveness and superiority over the other existing methods with an accuracy of 94%. The results of this work will contribute to the development of smart and interactive e-learning systems with adaptive responses based on users’ engagement levels.     

Immunohistochemical evaluation after Sr-enriched biphasic ceramic implantation in rabbits femoral neck: comparison of seven different bone conditions

Strontium (Sr) has shown effectiveness for stimulating bone remodeling. Nevertheless, the exact therapeutic values are not established yet. Authors hypothesized that local application of Sr-enriched ceramics would enhance bone remodeling in constant osteoporosis of rabbits’ femoral neck bone. Seven different bone conditions were analyzed: ten healthy rabbits composed a control group, while other twenty underwent ovariectomy and were divided into three groups. Bone defect was filled with hydroxyapatite 30% (HAP) and tricalcium phosphate 70% (TCP) granules in 7 rabbits, 5% of Sr-enriched HAP/TCP granules in 7, but sham defect was left unfilled in 6 rabbits. Bone samples were obtained from operated and non-operated legs 12 weeks after surgery and analyzed by histomorphometry and immunohistochemistry (IMH). Mean trabecular bone area in control group was 0.393 mm2, in HAP/TCP – 0.226 mm2, in HAP/TCP/Sr – 0.234 mm2 and after sham surgery – 0.242 mm2. IMH revealed that HAP/TCP/Sr induced most noticeable increase of nuclear factor kappa beta 105 (NFkB 105), osteoprotegerin (OPG), osteocalcin (OC), bone morphogenetic protein 2/4 (BMP 2/4), collagen type 1α (COL-1α), interleukin 1 (IL-1) with comparison to intact leg; NFkB 105 and OPG rather than pure HAP/TCP or sham bone. We concluded that Sr-enriched biomaterials induce higher potential to improve bone regeneration than pure bioceramics in constant osteoporosis of femoral neck bone. Further studies on bigger osteoporotic animals using Sr-substituted orthopedic implants for femoral neck fixation should be performed to confirm valuable role in local treatment of osteoporotic femoral neck fractures in humans.

Open image in new window

     

On Bayesian EWMA control charts under different loss functions

The motivation for this study is to analyze Bayesian exponentially weighted moving average (EWMA) control chart under 3 loss functions namely, SELF, LLF, and PLF. Informative priors (normal and mixture of normal) and non‐informative priors (Uniform and Jefferys) are considered for the analysis. The performance of Bayesian EWMA control chart using posterior and posterior predictive distribution scheme has been evaluated using average run length (ARL) and standard deviation run length (SDRL) as performance measures. Monte Carlo simulations are used to compute the performance measures for different values of smoothing constant. An illustrative example is also presented for practical considerations of Bayesian EWMA control chart.