The economic potential of bagasse cogeneration as CDM projects in Indonesia

Surplus bagasse in Indonesian sugar mills is potential for grid-connected electricity-generating projects under Clean Development Mechanism (CDM) scheme. In addition, it is further perceived to considerably support the efforts to address prevailing crises in domestic sugar industry and power generation sector. This paper aims at analyzing the economic potential of bagasse cogeneration as CDM projects in Indonesia with the main deliverables of total emission reductions per year and Certified Emission Reduction (CER) earnings. The analysis was made by following the applicable methodologies and based on publicly available data from official and other sources on the websites. The results show that with the electricity displacement potential at 260,253 MWh, Indonesia could generate Greenhouse Gas (GHG) emission reductions as much as 240,774 (large scale) or 198,177 tCO₂ (small scale) per annum from the recently-employed low efficiency cogeneration leading to the earnings of about US$1.36 or 1.12 million, respectively. Out of 6 regional grids where the electricity from the project activities can be grid-connected, the primary emission reductions potentials are encountered in Java-Bali and Southern Sumatera grids. Additionally, various barriers in technical, institutional, financial, and other aspects have been identified as the justifications to pass the additionality test.     

Injectable Hydrogels with In Situ Double Network Formation Enhance Retention of Transplanted Stem Cells

Stem cell transplantation via direct injection is a minimally invasive strategy being explored for treatment of a variety of injuries and diseases. Injectable hydrogels with shear moduli <50 Pa can mechanically protect cells during the injection process; however, these weak gels typically biodegrade within 1–2 weeks, which may be too fast for many therapeutic applications. To address this limitation, an injectable hydrogel is designed that undergoes two different physical crosslinking mechanisms. The first crosslinking step occurs ex vivo through peptide‐based molecular recognition to encapsulate cells within a weak gel that provides mechanical protection from injection forces. The second crosslinking step occurs in situ to form a reinforcing network that significantly retards material biodegradation and prolongs cell retention time. Human adipose‐derived stem cells are transplanted into the subcutaneous space of a murine model using hand‐injection through a 28‐gauge syringe needle. Cells delivered within the double‐network hydrogel are significantly protected from mechanical damage and have significantly enhanced in vivo cell retention rates compared to delivery within saline and single network hydrogels. These results demonstrate that in situ formation of a reinforcing network within an already existing hydrogel can greatly improve transplanted cell retention, thereby enhancing potential regenerative medicine therapies.     

Electrocatalysis for dioxygen reduction by a μ-oxo decavanadium complex in alkaline medium and its application to a cathode catalyst in air batteries

The redox behavior of a decavanadium complex [(V=O)₁₀(μ₂-O)₉(μ₃-O)₃(C₅H₇O₂)₆] (1) was studied using cyclic voltammetry under acidic and basic conditions. The reduction potential of V(V) was found at less positive potentials for higher pH electrolyte solutions. The oxygen reduction at complex 1 immobilized on a modified electrode was examined using cyclic voltammetry and rotating ring-disk electrode techniques in the 1 M KOH solutions. On the basis of measurements using a rotating disk electrode (RDE), the complex 1 was found to be highly active for the direct four-electron reduction of dioxygen at −0.2 V versus saturated calomel electrode (SCE). The complex 1 as a reduction catalyst of O₂ with a high selectivity was demonstrated using rotating ring-disk voltammograms in alkaline solutions. The application of complex 1 as an oxygen reduction catalyst at the cathode of zinc–air cell was also examined. The zinc–air cell with the modified electrode showed a stable discharge potential at approximately 1 V with discharge capacity of 80 mAh g⁻¹ which was about five times larger than that obtained with the commonly used manganese dioxide catalyst.     

A computational study of the role of chlorine in the partial oxidation of methane by MgO and Li/MgO

We investigate the surface defect chemistry of MgO and Li/MgO paying special attention to the effects of added chloride ions on the active sites in the materials when used as partial oxidation catalysts. We calculate that chloride ions will segregate to the surface of these materials and will be preferentially sited at low coordinate sites. The [LiCl] defect cluster is also calculated to be bound, both of which effects will have a major influence on catalytic properties. From our calculations we also comment on the siting and selectivities of the active sites in MgO and Li/MgO.     

Enhanced photocatalytic activity of Pt deposited on titania nanotube arrays for the hydrogen production with glycerol as a sacrificial agent

Photocatalytic activity of Pt-loaded TiO₂ nanotube arrays (Pt-TNTA) in the presence of glycerol as a sacrificial agent to produce H₂ has been studied. The effects of Pt loading and the methods by which it is deposited on TNTA (chemical reduction and photo-assisted deposition) were carefully examined. Intermediate products were also identified in order to scrutinise the reaction pathways of hydrogen generation in this particular system. FESEM imaging confirmed the formation of nantotubular structures of TiO₂ with average inner diameter of 80 nm, wall thickness of 20 nm, and length of approximately 2.5 μm. The generated nanotube arrays were of anatase structure with crystallite size within the range of 22–30 nm. Pt was successfully deposited on the surface of TNTA, as corroborated by EDX spectra, elemental mapping and TEM analysis. Band gap narrowing upon Pt loading was implied by UV–Vis DRS analysis, resulting in a band gap value of 2.93 eV, notably lower than a typical value of 3.2 eV associated with anatase. The photocatalyst sample with Pt deposited via a photo-assisted deposition method (Pt-TNTA-PDC) evidently outperformed its bare TNTA counterpart in producing hydrogen by 4.7 times, while that with Pt deposited by chemical reduction could improve H₂ production by 3.8 times. During photocatalytic operations, glycerol served an important purpose in suppressing electron-hole recombination by providing holes an oxidative target which is less energy-demanding than water. It is proposed that glycerol underwent dehydrogenation and decarbonylation processes producing ethylene glycol, followed by dehydration and oxidation towards acetic acid, before transforming into H₂ and CO₂, eventually. We suggest that Pt plays a role not only in the enhancement of H₂ photoproduction, but also in governing the direction of reactions, hence the intermediates and final products.     

Photocatalytic hydrogen production from glycerol–water mixture over Pt‐N‐TiO2 nanotube photocatalyst

The effects of several modifications on TiO₂ P25 in producing hydrogen from glycerol–water mixture have been investigated. Prior to further modification, TiO₂ underwent hydrothermal treatment at 130°C for several hours to obtain nanotube shape. TiO₂ nanotubes (TiNT) was then doped with platinum (Pt) and nitrogen (N) by employing photo‐deposition and impregnation method, respectively. SEM and XRD results showed that Pt‐N‐TiNT was successfully obtained as pure anatase crystal structure. The effects of glycerol content to photocatalytic activity of hydrogen production have also been studied, result in 50%v of glycerol as the optimum concentration correspond to the stoichiometric volume ratio of glycerol reforming. The results of photo‐production test showed that TiNT (nanotube) could enhance hydrogen generation by two times compared with unmodified P25 (nanoparticle). Meanwhile, simultaneous modification of TiNT by Pt and N dopants (Pt‐N‐TiNT) lead to activity improvement up to 13 times compared with P25. The output of this study may contribute toward finding an alternative pathway to produce H₂ from renewable resources. Copyright © 2012 John Wiley & Sons, Ltd.     

Impact of Sludge Floc Size and Water Composition on Dewaterability

In order to observe the impact of different water compositions on sludge dewaterability, assessments of floc sizes using a particle size analyzer and of sludge dewaterability based on the capillary suction time (CST) test were carried out. Synthetic raw water had small floc sizes, and synthetic domestic wastewater had both larger median floc sizes and a better correlation between sludge dewaterability and median floc sizes. The floc size distribution results showed that synthetic raw water is associated with a narrow particle size distribution. In comparison, synthetic domestic wastewater produced a wider distribution. However, the CST values were similar for both waters. Compared to synthetic wastewater, natural wastewater had the largest distribution with generally larger particle sizes.     

User satisfaction with business-to-employee portals: conceptualization and scale development

The purpose of this paper is to develop and validate the business-to-employee portal user satisfaction (B2EPUS) measure. Five sequential stages of scale development were undertaken to achieve this purpose: conceptual model development, item generation, content validation, exploratory study, and confirmatory study. Confirmatory factor analysis confirmed the five dimensions of the B2EPUS, namely Usefulness, Confidentiality, Ease of Use, Convenience of Access, and Portal Design as the dimensions of the construct. Competing model analysis indicates that the second-order factor model is the better fitting for the B2EPUS construct. The theoretical and practical implications of the study as well as directions for future research are discussed in the concluding sections of this paper.