Energy and environmental applications of carbon nanotubes

Energy and environment are major global issues inducing environmental pollution problems. Energy generation from conventional fossil fuels has been identified as the main culprit of environmental quality degradation and environmental pollution. In order to address these issues, nanotechnology plays an essential role in revolutionizing the device applications for energy conversion and storage, environmental monitoring, as well as green engineering of environmental friendly materials. Carbon nanotubes and their hybrid nanocomposites have received immense research attention for their potential applications in various fields due to their unique structural, electronic and mechanical properties. Here, we review the applications of carbon nanotubes (1) in energy conversion and storage such as in solar cells, fuel cells, hydrogen storage, lithium ion batteries and electrochemical supercapacitors, (2) in environmental monitoring and wastewater treatment for the detection and removal of gas pollutants, pathogens, dyes, heavy metals and pesticides and (3) in green nanocomposite design. Integration of carbon nanotubes in solar and fuel cells has increased the energy conversion efficiency of these energy conversion applications, which serve as the future sustainable energy sources. Carbon nanotubes doped with metal hydrides show high hydrogen storage capacity of around 6?wt% as a potential hydrogen storage medium. Carbon nanotubes nanocomposites have exhibited high energy capacity in lithium ion batteries and high specific capacitance in electrochemical supercapacitors, in addition to excellent cycle stability. High sensitivity and selectivity towards the detection of environmental pollutants are demonstrated by carbon nanotubes based sensors, as well as the anticipated potentials of carbon nanotubes as adsorbent to remove environmental pollutants, which show high adsorption capacity and good regeneration capability. Carbon nanotubes are employed as reinforcement material in green nanocomposites, which is advantageous in supplying the desired properties, in addition to the biodegradability. This article presents an overview of the advantages imparted by carbon nanotubes in electrochemical devices of energy applications and green nanocomposites, as well as nanosensor and adsorbent for environmental protection.     

Effect of pH on transport of Pb（2＋）,Mn（2＋）,Zn（2＋）and Ni（2＋） through lateritic soil： Column experiments and transport modeling

This study investigated the e ects of pH on the transport of Pb2+, Mn2+, Zn2+ and Ni2+ through lateritic soil columns. Model results by fitting the symmetric breakthrough curves (BTCs) of bromide (Br??) with CXTFIT model suggested that physical non-equilibrium processes were absent in the columns. The heavy metal BTCs were, however, asymmetrical and exhibited a tailing phenomenon, indicating the presence of chemical non-equilibrium processes in the columns. The retardation factors of Pb2+ were the largest of the four metal ions at both pH 4.0 (33.3) and pH 5.0 (35.4). The use of Langmuir isotherm parameters from batch studies with HYDRUS-1D did not predict the BTCs well. Rather the two-site model (TSM) described the heavy metal BTCs better than the equilibrium linear/nonlinear Langmuir model. The fraction of instantaneous sorption sites ( f ) of all four metal ions on the lateritic soil was consistently about 30%–44% of the total sorption sites.     

The power of reflection for would-be leaders: Investigating individual work reflection and its impact on leadership in teams

This paper examines the key role that individual work reflection plays in facilitating individuals' leadership in teams. Consistent with the functional perspective on leadership, we argue that individual work reflection allows individuals to better understand their team's needs, and therefore enact higher levels of task-, relational-, and change-oriented leadership behaviors and be more effective leaders in their teams. We first conducted a series of measure development studies to validate a measure of individual work reflection comprising four dimensions of reflection at work: goals-, methods-, relationships-, and self-focused reflection. Then, across two independent studies assessing individuals in self-managing teams over time, we found support for our theoretical model linking individual work reflection to peer-rated leadership behaviors (Main Studies 1 and 2) and leadership effectiveness (Main Study 2). In further support of our theorizing, Main Study 2 also indicates that individual work reflection shapes leadership behaviors and effectiveness via understanding the team's needs, beyond a wide range of related constructs (e.g., feedback seeking, mindfulness, and rumination), as well as commonly studied predictors of leadership behaviors (i.e., the Big Five). Our theory and empirical findings help advance insights on the role of individual work reflection in improving leadership outcomes in organizations.     

A Century of Plant Species Loss from an Isolated Fragment of Lowland Tropical Rain Forest

An isolated 4-ha fragment of lowland tropical rain forest has been preserved in the Singapore Botanic Gardens since their founding in 1859. The Botanic Gardens'Jungle has recently had enumerated all woody stems 5 cm diameter at breast height (dbh) and larger and the complete vascular plant flora inventoried. This inventory can be compared with the historic record of the flora of the Gardens'Jungle obtained from the extensive collection of herbarium specimens dating back to the 1890s. Of the 448 historically recorded native species, 220 are still present. Ninety-four native species for which there were no historic records and 80 introduced species were also recorded in the recent inventory. The 50.9% loss of plant species richness over approximately the last century has not been distributed uniformly across plant life-form groups. Tree species have been less likely to go extinct than shrubs, climbers, or epiphytes. But half of the tree species present in 1994 were represented by only one or two individuals ≥ 5 cm dbh and larger. Individual longevity may be the major correlate with persistence of plant species in isolated forest fragments. Shade-tolerant understory shrubs (mostly Rubiaceae ) and rattans ( Palmae ) have been particularly prone to extinction. Some species have probably proliferated during the period of isolation. The tree Calophyllum ferrugineum currently constitutes one quarter of all woody stems. A group of climbers has become very common and covers large areas, probably inhibiting tree regeneration. We conclude that tiny fragments will act as refuges for tropical rain-forest plant species for decades, possibly even centuries after isolation but on their own they will not provide a permanent guarantee of the conservation of tropical biodiversity.     

Treatment of methylene blue-containing wastewater using microorganisms supported on granular activated carbon under packed column operation

We studied the feasibility of using biological granular activated carbon-packed column in treating methylene blue-containing wastewater. The granular activated carbon with immobilized microbes was packed into a column and fed with 3 liter methylene blue-containing wastewater daily. With initial 1350 mg/l of methylene blue and 1550 mg/l of chemical oxygen demand, it was observed that the colour and chemical oxygen demand removal efficiencies were 99 and 78%, respectively. The high treatment performance of the system could be due to the simultaneous adsorption and biodegradation processes and advantages of immobilized microbes compare to suspended cell system.     

Determination of Polycyclic Aromatic Hydrocarbons in Rougan, a Traditional Chinese Barbecued Food, by Capillary Gas Chromatography

Several polycyclic aromatic hydrocarbons (PAHs), including those which are carcinogenic, have been detected in rougan, a traditional Chinese barbecued pork dish. The food samples were cleaned up by caustic digestion, solvent extraction, liquid-liquid partition, and column chromatography. The determination was carried out using capillary gas-chromatography with a flame ionization detector. A 25-m HP-1 capillary column was used. Fluorene, phenanthrene, anthracene, benzo[a]anthracene, chrysene and benzo[k]fluoranthene were detected in three of the five samples within the range of 3-17 ng/g. Fluoranthene and pyrene were detected in only two of the samples at similar levels. Two potent carcinogenic compounds, benzo[a]pyrene and benzo[b,j,k]fluoranthene, were not detected in any of the samples. No detectable PAHs have been found in meat cooked without the direct contact of food with flame and smoke. In barbecuing over an open charcoal fire, animal fat and juices dripping onto the open fire probably enhanced the formation of PAHs.     

吸烟与非吸烟肺癌患者中P53基因突变的检测

P53基因定位于人类第17号染色体的短臂,野生型P53基因是肿瘤抑制基因。这一基因正成为研究人类肿瘤DNA的主要目标。作者运用聚合酶链反应－单链构象多态性技术（PCR－SSCP）,研究了45例石蜡包埋的肺癌组织标本中肿瘤抑制基因P53基因突变,结果发现在P53基因的第5～8外显子中共检测到19例P53基因突变的样本,检出率为42.2％,并且发现吸烟的肺癌患者中P53基因突变的检出频率明显高于非吸烟的肺癌患者。     

Occurrence and suitability of pharmaceuticals and personal care products as molecular markers for raw wastewater contamination in surface water and groundwater

This study aimed to provide the first and comprehensive data on the occurrence of 17 target pharmaceuticals and personal care products (PPCPs) in urban water environment in Singapore. Meanwhile, this study also verified the suitability of these PPCPs as specific markers of raw wastewater contamination in receiving water bodies in highly urbanized areas where both surface water and groundwater are not impacted by the discharge of treated wastewater effluents. Analytical results of wastewater showed that among 17 target PPCPs examined, only 5 PPCPs were detected in 100 % of raw wastewater samples, including acetaminophen (ACT), carbamazepine (CBZ), caffeine (CF), diethyltoluamide (DEET), and salicylic acid (SA). Similarly, these PPCPs were found in most surface water and groundwater. Interestingly, the three PPCPs (ACT, CBZ, and SA) were only detected in surface water and groundwater in the sampling sites close to relatively older sewer systems, while they were absent in background samples that were collected from the catchment with no known wastewater sources. This suggests that ACT, CBZ, and SA can be used as specific molecular markers of raw wastewater in surface water and groundwater. This study also confirmed that CF and DEET were not really associated with wastewater sources, thus cannot serve well as specific molecular markers of wastewater contamination in receiving water bodies. To the best knowledge of the authors, the use of ACT and SA as specific molecular markers of raw wastewater contamination in urban surface waters and groundwater was first reported. Further studies on the use of ACT, CBZ, and SA along with other chemical/microbial markers are recommended to identify and differentiate contamination sources of surface waters/groundwater.     

Advanced Aerogels from Wool Waste Fibers for Oil Spill Cleaning Applications

Journal of Polymers and the Environment - Oil spills causes severe degradation to marine ecosystems and poses long term health effects on many animals on the food chain, including humans. A...     

UVA-irradiated dual photoanodes and dual cathodes photocatalytic fuel cell: mechanisms and Reactive Red 120 degradation pathways

Environmental Science and Pollution Research - To enhance dye removal and energy recovery efficiencies in single-pair electrode photocatalytic fuel cell (PFC-AC), dual cathodes PFC (PFC-ACC) and...