The composition of sugarcane juices dervied from burnt cane and whole green cane crop

There has been substantial interest within the Australian sugar industry in product diversification as a means to reduce its exposure to fluctuating raw sugar prices and in order to increase its commercial viability. In particular, the industry is looking at fibrous residues from sugarcane harvesting (trash) and from sugarcane milling (bagasse) for cogeneration and the production of biocommodities, as these are complementary to the core process of sugar production. A means of producing surplus residue (biomass) is to process whole sugarcane crop. In this paper, the composition of different juices derived from different harvesting methods, viz. burnt cane with all trash extracted (BE), green cane with half of the trash extracted (GE), and green cane (whole sugarcane crop) with trash unextracted (GU), were investigated and the results and comparison presented. The determination of electrical conductivity, inorganic composition, and organic acids indicate that both GU and GE cane juice contain a higher proportion of soluble inorganic ions and ionisable organic acids, compared to BE cane juice. It is important to note that there are considerably higher levels of Na ions and citric acid, but relatively low P levels in the GU samples. A higher level of reducing sugars was analysed in the GU samples than the BE samples due to the higher proportion of impurities found naturally in sugarcane tops and leaves. The purity of the first expressed juice (FEJ) of GU cane was on average higher than that of FEJ of BE cane. Results also show that GU juices appear to contain higher levels of proteins and polysaccharides, with no significant difference in starch levels.

SNAREing immunity : the role of SNAREs in the immune system

The trafficking of molecules and membranes within cells is a prerequisite for all aspects of cellular immune functions, including the delivery and recycling of cell surface proteins, secretion of immune mediators, ingestion of pathogens and activation of lymphocytes. SNARE (soluble-N-ethylmaleimide-sensitive-factor accessory-protein receptor)-family members mediate membrane fusion during all steps of trafficking, and function in almost all aspects of innate and adaptive immune responses. Here, we provide an overview of the roles of SNAREs in immune cells, offering insight into one level at which precision and tight regulation are instilled on immune responses.

Characterisation of sugarcane juice particles that influence the clarification process

Problems associated with processing whole sugarcane crop can be minimised by removing impurities during the clarification stage. As a first step, it is important to understand the colloidal chemistry of juice particles on a molecular level to assist development strategies for effective clarification performance. This paper presents the composition and surface characteristics of colloidal particles originating from various juice types by using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy (XPS) and zeta potential measurements. The composition and surface characteristics of colloidal juice particles are reported. The results indicate that there are three types of colloidal particles present viz., an aluminosilicate compound, silica and iron oxide, with the latter two being abundant. Proteins, polysaccharides and organic acids were identified on the surface of particles in juice. The overall particle charge varies from –2 mV to –6 mV. In comparison to juice expressed from burnt cane, the zeta potential values were more negative with juice particles originating from whole crop. This in part explains why these juices are difficult to clarify.

Insights to the Clarification of Sugar Cane Juice Expressed from Sugar Cane Stalk and Trash

Processing of juice expressed from green sugar cane containing all the trash (i.e., tops and leaves, the nonstalk component) of the sugar cane plant during sugar manufacture has been reported to lead to poor clarified juice (CJ) quality. Studies of different liming techniques have been conducted to identify which liming technique gives the best clarification performance from juice expressed from green cane containing half of all trash extracted (GE). Results have shown that lime saccharate addition to juice at 76 °C either continuous or batchwise gives satisfactory settling rates of calcium phosphate flocs(50−70 cm/min) and CJ with low turbidity and minimal amounts of mineral constituents. Surprisingly, the addition of phosphoric acid (≤300 mg/kg as P2O5), prior to liming to reduce juice turbidity (≤80%), increased the Mg (≤101%) and Si(≤148%) contents particularly for clarified GE juices. The increase was not proportional with increasing phosphoric acid dose. The nature of the flocs formed, including the zeta potential of the particles by the different liming techniques, has been used to account for the differences in clarification performance. Differences between the qualities of the CJ obtained with GE juice and that of burnt cane juices with all trash extracted (BE) have been discussed to provide further insights into GE processing.

Preparation and characterisation of composites from starch and sugar cane fibre

The aim of this study was to prepare and characterise composites of Soluble potato starch or hydroxypropylated maize starch with milled sugar cane fibre (i.e., bagasse). Prior to the preparation of the starch-fibre composites, the ‘cast’ and the ‘hot-pressed’ methods were investigated for the preparation of starch films in order to select the preferred preparation method. The physicochemical and mechanical properties of films conditioned at different relative humidities (RHs) were determined through moisture uptake, crystallinity, glass transition temperature (Tg), thermal properties, molecular structure and tensile tests. Hot-pressed starch films have ~5.5% less moisture, twice the crystallinity (~59%), higher Tg and Young’s modulus than cast starch films. The VH-type starch polymorph was observed to be present in the hot-pressed films. The addition of bagasse fibre to both starch types, prepared by hot-pressing, reduced the moisture uptake by up to 30% (cf., cast film) at 58% RH. The addition of 5 wt% fibre increased the tensile strength and Young’s modulus by 16% and 24% respectively. It significantly decreased the tensile strain by ~53%. Fourier Transform infrared (FT-IR) spectroscopy revealed differences in hydrogen bonding capacity between the films with fibre and those without fibre. The results have been explained on the basis of the intrinsic properties of starch and bagasse fibres.

Biological responses of human bone marrow mesenchymal stem cells to Sr-M-Si (M = Zn, Mg) silicate bioceramics

Strontium (Sr), Zinc (Zn), magnesium (Mg), and silicon (Si) are reported to be essential trace elements for the growth and mineralization of bone. We speculated that the combination of these bioactive elements in bioceramics may be effective to regulate the osteogenic property of boneforming cells. In this study, two Sr-containing silicate bioceramics, Sr2ZnSi2O7 (SZS) and Sr2MgSi2O7 (SMS), were prepared. The biological response of human bone marrow mesenchymal stem cells (BMSCs) to the two bioceramics (in the forms of powders and dense ceramic bulks) was systematically studied. In powder form, the effect of powder extracts on the viability and alkaline phosphatase (ALP) activity of BMSCs was investigated. In ceramic disc form, both direct and indirect coculture of BMSCs with ceramic discs were used to investigate their biological response, including attachment, proliferation, ALP activity, and bone-related genes expression. Beta-tricalcium phosphate (b-TCP) and akermanite (Ca2MgSi2O7, CMS) were used as control materials. The results showed that the Sr, Zn, and Si (or Sr, Mg, and Si)-containing ionic products from SZS and SMS powders enhanced ALP activity of BMSCs, compared to those from b-TCP. Both SZS and SMS ceramic discs supported the growth of BMSCs, and most importantly, significantly enhanced the ALP activity and bone-related genes expression of BMSCs as compared to b-TCP. The results suggest that the specific combination of bioactive ions (Sr, Zn, Si, e.g.) in bioceramics is a viable way to improve the biological performance of biomaterials, and the form of materials and surface properties were nonnegligible factors to influence cell response.

Environmental degradation of lignin/poly(hydroxybutyrate) blends

Blends of lignin and poly(hydroxybutyrate) (PHB) were obtained by melt extrusion. They were buried in a garden soil for up to 12 months, and the extent and mechanism of degradation were investigated by gravimetric analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Fourier transform infra-red spectroscopy (FTIR) over the entire range of compositions. The PHB films were disintegrated and lost 45 wt% of mass within 12 months. This value dropped to 12 wt% of mass when only 10 wt% of lignin was present, suggesting that lignin both inhibited and slowed down the rate of PHB degradation. TGA and DSC indicated structural changes, within the lignin/PHB matrix, with burial time, while FTIR results confirmed the fragmentation of the PHB polymer. XPS revealed an accumulation of biofilms on the surface of buried samples, providing evidence of a biodegradation mechanism. Significant surface roughness was observed with PHB films due to microbial attack caused by both loosely and strongly associated micro-organisms. The presence of lignin in the blends may have inhibited the colonisation of the micro-organisms and caused the blends to be more resistant to microbial attack. Analysis suggested that lignin formed strong hydrogen bonds with PHB in the buried samples and it is likely that the rate of breakdown of PHB is reduced, preventing rapid degradation of the blends.

3D-printing of highly uniform CaSiO3 ceramic scaffolds : preparation, characterization and in vivo osteogenesis

Calcium silicate (CaSiO3, CS) ceramics have received significant attention for application in bone regeneration due to their excellent in vitro apatite-mineralization ability; however, how to prepare porous CS scaffolds with a controllable pore structure for bone tissue engineering still remains a challenge. Conventional methods could not efficiently control the pore structure and mechanical strength of CS scaffolds, resulting in unstable in vivo osteogenesis. The aim of this study is to set out to solve these problems by applying a modified 3D-printing method to prepare highly uniform CS scaffolds with controllable pore structure and improved mechanical strength. The in vivo osteogenesis of the prepared 3D-printed CS scaffolds was further investigated by implanting them in the femur defects of rats. The results show that the CS scaffolds prepared by the modified 3D-printing method have uniform scaffold morphology. The pore size and pore structure of CS scaffolds can be efficiently adjusted. The compressive strength of 3D-printed CS scaffolds is around 120 times that of conventional polyurethane templated CS scaffolds. 3D-Printed CS scaffolds possess excellent apatite-mineralization ability in simulated body fluids. Micro-CT analysis has shown that 3D-printed CS scaffolds play an important role in assisting the regeneration of bone defects in vivo. The healing level of bone defects implanted by 3D-printed CS scaffolds is obviously higher than that of 3D-printed b-tricalcium phosphate (b-TCP) scaffolds at both 4 and 8 weeks. Hematoxylin and eosin (H&E) staining shows that 3D-printed CS scaffolds induce higher quality of the newly formed bone than 3D-printed b-TCP scaffolds. Immunohistochemical analyses have further shown that stronger expression of human type I collagen (COL1) and alkaline phosphate (ALP) in the bone matrix occurs in the 3D-printed CS scaffolds than in the 3D-printed b-TCP scaffolds. Considering these important advantages, such as controllable structure architecture, significant improvement in mechanical strength, excellent in vivo osteogenesis and since there is no need for second-time sintering, it is indicated that the prepared 3D-printed CS scaffolds are a promising material for application in bone regeneration.

Compressive behaviour of nanocrystalline Mg-5Al alloys

Magnesium alloys are attracting increasing research interests due to their low density, high specific strength, good machinability and availability as compared to other structural materials. However, the deformation and failure mechanisms of nanocrystalline (nc) Mg alloys have not been well understood. In this work, the deformation behaviour of nc Mg-5Al alloys was investigated using compression test, with focus on the effects of grain size. The average grain size of the Mg- Al alloy was changed from 13 to 50 nm via mechanical milling. The results showed that grain size had a significant influence on the yield stress and ductility of the Mg alloys, and the materials exhibited increased strain rate sensitivity with a decrease in grain size. The deformation mechanisms were also strongly dependent on the grain sizes.

Preparation, characterization and in vitro angiogenic capacity of cobalt substituted β-tricalcium phosphate ceramics

Divalent cobalt ions (Co2+) have been shown to possess the capacity to induce angiogenesis by activating hypoxia inducible factor-1α (HIF-1α) and subsequently inducing the production of vascular endothelial growth factor (VEGF). However, there are few reports about Co-containing biomaterials for inducing in vitro angiogenesis. The aim of the present work was to prepare Co-containing β-tricalcium phosphate (Co-TCP) ceramics with different contents of calcium substituted by cobalt (0, 2, 5 mol%) and to investigate the effect of Co substitution on their physicochemical and biological properties. Co-TCP powders were synthesized by a chemistry precipitation method and Co-TCP ceramics were prepared by sintering the powder compacts. The effect of Co substitution on phase transition and the sintering property of the β-TCP ceramics was investigated. The proliferation and VEGF expression of human bone marrow mesenchymal stem cells (HBMSCs) cultured with both powder extracts and ceramic discs of Co-TCP was further evaluated. The in vitro angiogenesis was evaluated by the tube-like structure formation of human umbilical vein endothelial cells (HUVECs) cultured on ECMatrix™ in the presence of powder extracts. The results showed that Co substitution suppressed the phase transition from β- to α-TCP. Both the powder extracts and ceramic discs of Co-TCP had generally good cytocompatibility to support HBMSC growth. Importantly, the incorporation of Co into β-TCP greatly stimulated VEGF expression of HBMSCs and Co-TCP showed a significant enhancement of network structure formation of HUVECs compared with pure TCP. Our results suggested that the incorporation of Co into bioceramics is a potential viable way to enhance angiogenic properties of biomaterials. Co-TCP bioceramics may be used for bone tissue regeneration with improved angiogenic capacity.

Characterisation of sugarcane juice particles that influence the clarification process

Problems associated with processing whole sugarcane crop can be minimised by removing impurities during the clarification stage. As a first step, it is important to understand the colloidal chemistry of juice particles on a molecular level to assist development of strategies for effective clarification performance. This paper presents the composition and surface characteristics of colloidal particles originating from various juice types by using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy(XPS) and zeta potential measurements. The composition and surface characteristics of colloidal juice particles are reported. The results indicate that there are three types of colloidal particles present, viz. an aluminosilicatecompound, silica and iron oxide, with the latter two being abundant. Proteins, polysaccharides and organic acids were identified on the surface of particles in juice. The overall particle charge varies from -2 mV to -6 mV. In comparison to juice expressed from burnt cane, the zeta potential values were more negative with juice particles originating from whole crop. This in part explains why these juices are difficult to clarify.

Self-assembled hyperbranched polymer - gold nanoparticle hybrids : understanding the effect of polymer coverage on assembly size and SERS performance

In the past few years, remarkable progress has been made in unveiling novel and unique optical properties of strongly coupled plasmonic nanostructures. However, application of such plasmonic nanostructures in biomedicine remains challenging due to the lack of facile and robust assembly methods for producing stable nanostructures. Previous attempts to achieve plasmonic nano-assemblies using molecular ligands were limited due to the lack of flexibility that could be exercised in forming them. Here, we report the utilization of tailor-made hyperbranched polymers (HBP) as linkers to assemble gold nanoparticles (NPs) into nano-assemblies. The ease and flexibility in tuning the particle size and number of branch ends of a HBP makes it an ideal candidate as a linker, as opposed to DNA, small organic molecules and linear or dendrimeric polymers. We report a strong correlation of polymer (HBP) concentration with the size of the hybrid nano-assemblies and “hot-spot” density. We have shown that such solutions of stable HBP-gold nano-assemblies can be barcoded with various Raman tags to provide improved surface-enhanced Raman scattering (SERS) compared with non-aggregated NP systems. These Raman barcoded hybrid nano-assemblies, with further optimization of NP shape, size and “hot-spot” density, may find application as diagnostic tools in nanomedicine.

Selective reductions using visible light photocatalysts of supported gold nanoparticles

Photocatalytic synthesis using visible light is a desirable chemical process because of its potential to utilize sunlight. Supported gold nanoparticles (Au-NPs) were found to be efficient photocatalysts and the effects of the supports were identified including CeO2, TiO2, ZrO2, Al2O3, and zeolite Y. In particular Au/CeO2 exhibited the high catalytic activity to reduce nitroaromatics to azo compounds, hydrogenate azobenzene to hydroazobenzene, reduce ketones to alcohols, and deoxygenate epoxides to alkenes at ambient temperatures, under irradiation of visible light (or simulated sunlight). The reac-tive efficiency depends on two primary factors: one is the light adsorption of catalysts and another is the driving ability of catalysts corresponding to the reactants. The light absorption by Au-NPs is due to surface plasmon resonance effect or inter-band electron transition; this is related to the reduction ability of the photocatalysts. Irradiation with shorter wavelengths can excite the conduction electrons in Au-NPs to higher energy levels and as a result, induce reduction with more negative reduction potentials. It is known when irradiated with light the Au-NPs can abstract hydrogen from isopropanol forming Au-H species on the Au-NP surface. Hence, we proposed that the active Au-H species will react with the N=O, N=N, C=O double bonds or epoxide bonds, which are weakened by the interaction with the excited electrons in the Au-NPs, and yield the final reductive products. The reacting power of the Au-H species depends on the energy of the excited electrons in Au-NPs: the higher the electronic energy, the stronger the reduction ability of the Au-H species. This finding demonstrates that we can tune the reduction ability of the photocatalysts by manipulating the irradiation wavelength.

Nagelschmidtite bioceramics with osteostimulation properties : material chemistry activating osteogenic genes and WNT signalling pathway of human bone marrow stromal cells

Bioactive materials with osteostimulation properties are of great importance to promote osteogenic differentiation of human bone marrow stromal cells (hBMSCs) for potential bone regeneration. We have recently synthesized nagelschmidtite (NAGEL, Ca7Si2P2O16) ceramic powders which showed excellent apatite-mineralization ability. The aim of this study was to investigate the interaction of hBMSCs with NAGEL bioceramic bulks and their ionic extracts, and to explore the osteostimulation properties of NAGEL bioceramics and the possible molecular mechanism. The cell attachment, proliferation, bone-related gene expression (ALP, OPN and OCN) and WNT signalling pathways (WNT3a, FZD6, AXIN2 and CTNNB) of hBMSCs cultured on NAGEL bioceramic disks were systematically studied. We further investigated the biological effects of ionic products from NAGEL powders on cell proliferation and osteogenic differentiation of hBMSCs by culturing cells with NAGEL extracts. Furthermore, the effect of NAGEL bioceramics on the osteogenic differentiation in hBMSCs was also investigated with the addition of cardamonin, a WNT inhibitor. The results showed that NAGEL bioceramic disks supported the attachment and proliferation of hBMSCs, and significantly enhanced the bone-related gene expression and WNT signalling pathway of hBMSCs, compared to conventional beta-tricalcium phosphate (β-TCP) bioceramic disks and blank controls. The ionic products from NAGEL powders also significantly promoted the proliferation, bone and WNT-related gene expression of hBMSCs. It was also identified that NAGEL bioceramics could bypass the action of the WNT inhibitor (10 μM) to stimulate the selected osteogenic genes in hBMSCs. Our results suggest that NAGEL bioceramics possess excellent in vitro osteostimulation properties. The possible mechanism for the osteostimulation may be directly related to the released Si, Ca and P-containing ionic products from NAGEL bioceramics which activate bone-related gene expression and WNT signalling pathway of hBMSCs. The present study suggests that NAGEL bioceramics are a potential bone regeneration material with significant osteostimulation capacity.

Synthesis and characterisation of nanoscale magnesium oxide powders and their application in thick films of Bi2Sr2CaCu2O8

Nanoscale MgO powder was synthesized from magnesite ore by a wet chemical method. Acid dissolution was used to obtain a solution from which magnesium containing complexes were precipitated by either oxalic acid or ammonium hydroxide, The transformation of precipitates to the oxide was monitored by thermal analysis and XRD and the transformed powders were studied by electron microscopy. The MgO powders were added as dopants to Bi2SrCa2CuO8 powders and high temperature superconductor thick films were deposited on silver. Addition of suitable MgO powder resulted in increase of critical current density, J(c), from 8,900 Acm(-2) to 13,900 Acm(-2) measured at 77 K and 0 T. The effect of MgO addition was evaluated by XRD, electron microscopy and critical current density measurements. (C) 1998 Elsevier Science B.V.