Fundamental studies on wood/cellulose-plastic composites: effects of composition and cellulose dimension on the properties of cellulose/PP composite

Although wood/cellulose-plastic composites (WPC) of low wood/cellulose content have been more accepted worldwide and are promoted as low-maintenance, high-durability building products, composites containing high wood/cellulose content are not yet developed on an industrial scale. In this study, flow properties, mechanical properties, and water absorption properties of the compounds of cellulose microfiber/polypropylene (PP) and maleic anhydride-grafted polypropylene (MAPP) were investigated to understand effects of the high cellulose content and the dimensions of the cellulose microfiber. The molding processes studied included compression, injection, and extrusion. It was found that fluidity is not only dependent on resin content but also on the dimension of the filler; fluidity of the compound declined with increased fiber length with the same resin content. Dispersion of the composite was monitored by charge-coupled device (CCD) microscope. Increasing the plastic content in the cellulose-plastic formulation improved the strength of mold in addition to the bond development between resin and filler, and the tangle of fibers. The processing mode affected the physicomechanical properties of the cellulosic plastic. Compression-molded samples exhibited the lowest modulus of rupture (MOR) and modulus of elasticity (MOE) and the highest water absorption, while samples that were injection-molded exhibited the highest MOR (70 MPa) and MOE (7 GPa) and low water absorption (2%).     

Effect of nano-SiO2 on properties of wood/polymer/clay nanocomposites

Wood polymer nanocomposites (WPNC) based on nano-SiO₂ were prepared by impregnation of styrene acrylonitrile copolymer (SAN), SiO₂ nanoparticles modified with γ-trimethoxy silyl propyl methacrylate (MSMA), and nanoclay into wood. The structure of modified SiO₂ nanoparticles and WPNC was characterized by Fourier transform infrared spectroscopy (FTIR). XRD analysis showed the delaminated structure of SAN/SiO₂/clay-treated wood composites. The synergistic effect of nano-SiO₂ and nanoclay was investigated. Thermal stability of SiO₂ nanoparticles decreased after modification, while that of wood treated with SAN, SiO₂, and nanoclay improved. Morphological characteristics were examined by scanning electron microscopy (SEM). Mechanical properties, water uptake (%), dimensional stability, hardness, and flammability were found to improve due to incorporation of SiO₂ and nanoclay into wood polymer composites. Maximum improvement in properties was observed in the wood polymer composites containing SiO₂ and nanoclay at the ratio of 1:1.     

Effect of nanofillers on flame retardancy, chemical resistance, antibacterial properties and biodegradation of wood/styrene acrylonitrile co-polymer composites

Wood polymer nanocomposites (WPNCs) based on simul wood (Bombex ceiba, L.) were prepared by impregnation of styrene acrylonitrile copolymer, γ-methacryloyloxy trimethyl silane-modified TiO₂, SiO₂ nanoparticles and nanoclay intercalating mixture through vacuum impregnation. The impact of nanofillers on the physical properties, flame retardancy, water resistance, anti-swelling efficiency and biodegradability of the resultant WPNCs was investigated. Remarkable enhancement in wood properties such as flame retardancy, water resistance and anti-swelling efficiency was achieved with the treatment. The results showed that all the properties were maximum for wood samples treated with SAN/TiO₂ (0.5 %)/SiO₂ (0.5 %)/nanoclay (0.5 %). The presence of TiO₂ nanoparticles in WPNC exhibited antibacterial activity. The resistance to biodegradation was observed by incorporation of nanofillers into wood.     

Hunger and health among undocumented Mexican migrants in a US urban area

OBJECTIVES: To measure the occurrence and correlates of hunger and to evaluate the association between hunger and three health indicators among undocumented Mexican immigrants. DESIGN: Non-probability cross-sectional sample. SETTING: Neighbourhoods within New York City. SUBJECTS: Four hundred and thirty-one undocumented Mexican immigrants living in the USA. RESULTS: Hunger was indicated by approximately 28% of respondents. In a multivariate model, working as a day labourer was associated with hunger (odds ratio (OR) 3.33, 95% confidence interval (CI) 1.83-6.06) while receiving public assistance protected against hunger (OR 0.23, 95% CI 0.06-0.88). In multivariate models, respondents who reported experiencing hunger also reported poorer overall health (OR 1.69, 95% CI 0.95-3.02) and more days of poor mental (P = 0.045) and physical health (P < 0.0001). Greater amount of time lived in the USA was also associated with worse overall health (P = 0.054) and more days of poor mental and physical health (P < 0.01). CONCLUSIONS: The present study shows that food insecurity and hunger may be problems among undocumented migrants living in the USA. Uncertain and unpredictable work schedules and limited access to public assistance may contribute to high levels of hunger, which in turn may also negatively affect mental and physical health. Increasing amount of time lived in the USA is also associated with poorer health indicators. Programmes that provide undocumented migrants with emergency access to resources may reduce food insecurity and lead to improved health outcomes among this vulnerable population.     

Soil and nutrients losses under different crop covers in vertisols of Central India

Purpose

Accelerated erosion removes fertile top soil along with nutrients through runoff and sediments, eventually affecting crop productivity and land degradation. However, scanty information is available on soil and nutrient losses under different crop covers in a vertisol of Central India. Thus, a field experiment was conducted for 4 years (2010–2013) to study the effect of different crop cover combinations on soil and nutrient losses through runoff in a vertisol.

Materials and methods

Very limited information is available on runoff, soil, and nutrient losses under different vegetative covers in a rainfed vertisol. Thus, the hypothesis of the study was to evaluate if different crop cover combinations would have greater impact on reducing soil and nutrient losses compared to control plots in a vertisol.

This experiment consisted of seven treatment combinations of crop covers namely soybean (Glycine max) (CC₁), maize (Zea mays) (CC₂), pigeon pea (Cajanus cajan) (CC₃), soybean (Glycine max)?+?maize (Zea mays) ??1:1 (CC₄), soybean (Glycine ma x))?+?pigeon pea (Cajanus cajan) ?2:1 (CC₅), maize (Zea mays)?+?pigeon pea (Cajanus cajan) ??1:1 (CC₆), and cultivated fallow (CC₇). The plot size was 10?×?5 m with 1% slope, and runoff and soil loss were measured using multi-slot devisor. All treatments were arranged in a randomized block design with three replications.

Results and discussion

Results demonstrated that the runoff and soil loss were significantly (p?<?0.05) higher (289 mm and 3.92 Mg ha^?1) under cultivated fallow than those in cropped plots. Among various crop covers, sole pigeon pea (CC₃) recorded significantly higher runoff and soil loss (257 mm and 3.16 Mg ha^?1) followed by that under sole maize (CC₂) (235 mm and 2.85 Mg ha^?1) and the intercrops were in the order of maize?+?pigeon pea (211 mm and 2.47 Mg ha^?1) followed by soybean?+?maize (202 mm and 2.38 Mg ha^?1), and soybean?+?pigeon pea (195 mm and 2.15 Mg ha^?1). The lowest runoff and soil loss were recorded under soybean sole crop (194 mm and 2.27 Mg ha^?1). The data on nutrient losses indicated that the highest losses of soil organic carbon (SOC) (25.83 kg ha^?1), total nitrogen (N), phosphorus (P), and potassium (K) (7.76, 0.96, 32.5 kg ha^?1) were recorded in cultivated fallow (CC₇) as compared to those from sole and intercrop treatments. However, sole soybean and its intercrops recorded the minimum losses of SOC and total N, P, and K, whereas the maximum losses of nutrients were recorded under pigeon pea (CC₃). The system productivity in terms of soybean grain equivalent yield (SGEY) was higher (p?<?0.05) from maize?+?pigeon pea (3358 kg ha^?1) followed by that for soybean?+?pigeon pea (2191 kg ha^?1) as compared to sole soybean. Therefore, maize?+?pigeon pea (1:1) intercropping is the promising option in reducing runoff, soil-nutrient losses, and enhancing crop productivity in the hot sub-humid eco-region.

Conclusions

Study results highlight the need for maintenance of suitable vegetative cover as of great significance to diffusing the erosive energy of heavy rains and also safe guarding the soil resource from degradation by water erosion in vertisols.

     

Efficacy of nano-hydroxyapatite prepared by an aqueous solution combustion technique in healing bone defects of goat

The present study was undertaken to evaluate porous hydroxyapatite (HAp), the powder of which was prepared by a novel aqueous solution combustion technique, as a bone substitute in healing bone defects in vivo, as assessed by radiologic and histopathologic methods, oxytetracycline labeling, and angiogenic features in Bengal goat. Bone defects were created in the diaphysis of the radius and either not filled (group I) or filled with a HAp strut (group II). The radiologic study in group II showed the presence of unabsorbed implants which acted as a scaffold for new bone growth across the defect, and the quality of healing of the bone defect was almost indistinguishable from the control group, in which the defect was more or less similar, although the newly formed bony tissue was more organized when HAp was used. Histologic methods showed complete normal ossification with development of Haversian canals and well-defined osteoblasts at the periphery in group II, whereas the control group had moderate fibro-collagenization and an adequate amount of marrow material, fat cells, and blood vessels. An oxytetracycline labeling study showed moderate activity of new bone formation with crossing-over of new bone trabeculae along with the presence of resorption cavities in group II, whereas in the control group, the process of new bone formation was active from both ends and the defect site appeared as a homogenous non-fluoroscent area. Angiograms of the animals in the control group showed uniform angiogenesis in the defect site with establishment of trans-transplant angiogenesis, whereas in group II there was complete trans-transplant shunting of blood vessel communication. Porous HAp ceramic prepared by an aqueous combustion technique promoted bone formation over the defect, confirming their biologic osteoconductive property.     

Evaluation of Differential Pore-Volume Distribution (DPVD) Patterns of Porous Clinoptilolite Fractions

Analysis of differential pore-volume distribution (DPVD) patterns of a commercial Clinoptilolite has been conducted experimentally using an analyzer by measuring the N₂ adsorption isotherm. The commercial material was fractionated by sieving through sequential sieves: <125 µ (Z8; fine), 125–250 µ (Z9; medium), and >250 µ (Z10; coarse). The DPVD of the fractions were calculated from the hysteresis loop according to the adsorption and desorption curves of Dollimore-Heal (DH) model. The adsorption cycle had produced dissimilar differential pore volume distribution patterns. For the 10-nm pore width, fine and medium fractions had a maximum pore volume up to 0.0016 cm³/g nm, while the coarse fraction had a little greater value up to 0.002 cm³/g nm. Moreover, the medium fraction had too many hills and valleys in the DPVD. However, the desorption cycle–based DH analysis did not show any marked variation in the DPVD pattern.     

Induction,purification and partial characterization of vitellogenin in an Indian major carp Catla catla (Ham.)

Vitellogenin was purified from the serum of 17‐β estradiol (E₂)‐induced juvenile Catla catla using a simple two‐step purification procedure i.e. selective chemical precipitation followed by gel filtration chromatography. Purified protein migrated as single band in a native gradient PAGE which indicated the purity of the sample. The molecular weight of the native catla vitellogenin (~440 kDa) was determined using gel filtration chromatography. In SDS‐PAGE under reducing conditions catla vitellogenin dissociated into three major sub units at 115 kDa, 102 kDa and 73 kDa along with a few faint bands. Confirmation of purified protein as catla vitellogenin was supported by multiple physiological evidences, e.g. absence in male as well as juvenile sera and presence in matured female fish, ability to be synthesized upon estradiol injection in immature fish and certain unique biochemical properties like high molecular weight, phospholipoglycoprotein nature of the molecule. Western blot analysis showed that polyclonal antibody raised against purified protein detected vitellogenin in the sera of catla and in a few species selected from Cyprinidae family. These antisera were used to detect vitellogenin in liver tissue of hormone‐induced catla using immunohistochemistry and its applicability in other immunoassays is discussed.