Metal-free graphitic carbon nitride as mechano-catalyst for hydrogen evolution reaction

Graphitic carbon nitride (g-C3N4), as a promising metal-free catalyst for photo-catalytic and electrochemical water splitting, has recently attracted tremendous research interest. However, the underlying catalytic mechanism for the hydrogen evolution reaction (HER) is not fully understood. By using density functional theory calculations, here we have established that the binding free energy of hydrogen atom (ΔGH∗0) on g-C3N4 is very sensitive to mechanical strain, leading to substantial tuning of the HER performance of g-C3N4 at different coverages. The experimentally-observed high HER activity in N-doped graphene supported g-C3N4 (Zheng et al., 2014) is actually attributed to electron-transfer induced strain. A more practical strategy to induce mechanical strain in g-C3N4 is also proposed by doping a bridge carbon atom in g-C3N4 with an isoelectronic silicon atom. The calculated ΔGH∗0 on the Si-doped g-C3N4 is ideal for HER. Our results indicate that g-C3N4 would be an excellent metal-free mechano-catalyst for HER and this finding is expected to guide future experiments to efficiently split water into hydrogen based on the g-C3N4 materials.

Carbon nanodot decorated graphitic carbon nitride: New insights into the enhanced photocatalytic water splitting from ab initio studies

Interfacing carbon nanodots (C-dots) with graphitic carbon nitride (g-C3N4) produces a metal-free system that has recently demonstrated significant enhancement of photo-catalytic performance for water splitting into hydrogen [Science, 2015, 347, 970–974]. However, the underlying photo-catalytic mechanism is not fully established. Herein, we have carried out density functional theory (DFT) calculations to study the interactions between g-C3N4 and trigonal/hexagonal shaped C-dots. We find that hybrid C-dots/g-C3N4 can form a type-II van der Waals heterojunction, leading to significant reduction of band gap. The C-dot decorated g-C3N4 enhances the separation of photogenerated electron and hole pairs and the composite's visible light response. Interestingly, the band alignment of C-dots and g-C3N4 calculated by the hybrid functional method indicates that C-dots act as a spectral sensitizer in hybrid C-dots/g-C3N4 for water splitting. Our results offer new theoretical insights into this metal-free photocatalyst for water splitting.

Thermal conductivity of a new carbon nanotube analog: The diamond nanothread

Based on the non-equilibrium molecular dynamics simulations, we have studied the thermal conductivities of a novel ultra-thin one-dimensional carbon nanomaterial - diamond nanothread (DNT). Unlike single-wall carbon nanotube (CNT), the existence of the Stone-Wales transformations in DNT endows it with richer thermal transport characteristics. There is a transition from wave-dominated to particle-dominated transport region, which depends on the length of poly-benzene rings. However, independent of the transport region, strong length dependence in thermal conductivity is observed in DNTs with different lengths of poly-benzene ring. The distinctive SW characteristic in DNT provides more degrees of freedom to tune the thermal conductivity not found in the homogeneous structure of CNT. Therefore, DNT is an ideal platform to investigate various thermal transport mechanisms at the nanoscale. Its high tunability raises the potential to design DNTs for different applications, such as thermal connection and temperature management.

Protein turnover in malnourished patients with cystic fibrosis: Effects of elemental and nonelemental nutritional supplements

To evaluate the relative efficacy of nonele-mental versus semielemental enteral supplements for nutritional rehabilitation of cystic fibrosis (CF) patients, whole-body protein turnover using the [15N]glycine method was studied in nine malnourished CF patients during enteral feedings, in a block design study compar-ing a semielemental formula (Criticare), a higher protein density but nonelemental formula (Traumacal) (T), and a nonelemental formula that had been modified to become isocaloric and isonitrogenous to the semielemental formula (modified Traumacal, MT). No significant differences in rates of protein synthesis or catabolism were observed comparing the three formulas. However the higher protein density nonelemental formula resulted in higher net protein deposition compared to the other two formulas (T + 0.42 g kg-110 h-1versus 0.33 g kg-110 h-1for Criticare and-0.59 g kg-110 h-1for MT), although this was significant (p < 0.05) for the MT versus T comparison only. This study lends support to the use of less expensive nonelemental formulas for the nutritional management of malnourished patients with CF. © 1990 Raven Press Ltd, New York.

Short-term nutritional supplementation during management of pulmonary exacerbations in cystic fibosis: A controlled study, including effects of protein turnover

Effects of nutritional supplements on minimizing weight loss and abnormalities of protein turnover during pulmonary exacerbations in cystic fibrosis (CF) were studied by controlled trial. Patients received pulmonary therapy and either standard diet (n = 10) or adjunctive enteral supplements (n = 12). Initial protein turnover, measured by [15N]glycine kinetics, showed alterations of protein synthesis (P Syn) and catabolism (P Cat), which correlated with the degree of underweight, and negligible net protein deposition (P Dep). With treatment both groups had significant increases in mean body weight and forced expiratory volume in 1 s, expressed as percent predicted value for height (FEV1) by 3 wk, but a significant correlation between initial underweight and subsequent weight gain was observed only in supplemented patients. Mean P Syn and P Dep increased significantly (p < 0.001) only in the supplemented group. Pulmonary exacerbations in CF have important adverse effects on body-protein metabolism, similar to changes in protein-energy malnutrition and infection. These effects are reversed by short-term nutritional support. Strategic nutritional intervention should thus be considered in management, especially in malnourished patients.

Sustainable me - a pharmacist’s role in reducing the carbon footprint of healthcare delivery

Introduction Climate change has been described as the most significant global health threat of the 21st century. Already, negative impacts on human health and wellbeing are being observed. These impacts present enormous challenges for the healthcare sector and the time has come for healthcare professionals to demonstrate leadership in addressing these challenges. Since any unsustainable organizational practices of healthcare organisations may ultimately have a negative impact on human health, there is an implicit moral obligation for these organisations and the people who work in them, to deliver healthcare more sustainably. If one considers that in 2010 pharmaceuticals comprised 22% of the carbon footprint of the NHS England (equating to 4.4 million tonnes of CO2 emissions) and 3% of England’s total carbon footprint (NHS Sustainable Development Unit, 2012), by reducing the carbon footprint of pharmaceuticals used in their healthcare organisations, pharmacists can have a significant impact on reducing the organisation’s total carbon footprint and ultimately on the public’s health. Aims The engagement of pharmacists with sustainability initiatives in the workplace has been largely unreported in international and national pharmacy journals. This paper aims to highlight the important role that pharmacists can play in helping to reduce the carbon footprint of healthcare delivery. Methods Literature was reviewed to identify areas where pharmacists could influence the more sustainable use of pharmaceuticals in their organisations. Discussion Much of the carbon footprint of pharmaceuticals is embedded carbon from their manufacture and delivery. Through efficient inventory management practices, pharmacists can reduce the number of orders and potentially reduce the number of deliveries required. Pharmacists can also help to reduce the amount of pharmaceutical waste generated. Of the waste that is generated, they can help improve the segregation of waste streams to increase the amount of non-contaminated packaging waste that is recycled and reduce the amount of pharmaceutical waste being incinerated or ending up in landfill. Reference NHS Sustainable Development Unit. (2012). Sustainability in the NHS Health Check 2012. NHS Sustainable Development Unit. Cambridge, UK: NHS Sustainable Devlopment Unit.

The Context-integrity of the global carbon regime: The relevance and impact of the World Trade Organization

In the study of the integrity of the global carbon regime there are a number of institutions that must be considered for their impacts on this system. In particular, the subject matter of this chapter is concerned with the main international institution for trade, the World Trade Organization (the WTO). Otherwise stated, this chapter is concerned with how the institutional integrity of the global carbon regime aligns with the values and policy objectives of the WTO. This is done with a view to consider whether the global carbon regime aligns with these values and objectives in a way demonstrative of context-integrity. This alignment is not a single-sided undertaking and, therefore, it is essential that the underlying values of the WTO themselves align with the global carbon regime. I suggest this is particularly crucial given the importance of the objectives of the climate change regime, and the scientific predictions of the current climate projections.

Direct electrochemical formation of nanostructured amorphous Co(OH)2 on gold electrodes with enhanced activity for the oxygen evolution reaction.

The oxides of cobalt have recently been shown to be highly effective electrocatalysts for the oxygen evolution reaction (OER) under alkaline conditions. In general species such as Co3O4 and CoOOH have been investigated that often require an elevated temperature step during their synthesis to create crystalline materials. In this work we investigate the rapid and direct electrochemical formation of amorphous nanostructured Co(OH)2 on gold electrodes under room temperture conditions which is a highly active precursor for the OER. During the OER some conversion to crystalline Co3O4 occurs at the surface, but the bulk of the material remains amorphous. It is found that the underlying gold electrode is crucial to the materials enhanced performance and provides higher current density than can be achieved using carbon, palladium or copper support electrodes. This catalyst exhibits excellent activity with a current density of 10 mA cm-2 at an overpotential of 360 mV with a high turnover frequency of 2.1 s-1 in 1 M NaOH. A Tafel slope of 56 mV dec-1 at low overpotentials and a slope of 122 mV dec-1 at high overpotentials is consistent with the dual barrier model for the electrocatalytic evolution of oxygen. Significantly, the catalyst maintains excellent activity for up to 24 hr of continuous operation and this approach offers a facile way to create a highly effective and stable material.

Room temperature gas sensing properties of ultrathin carbon nanotubes by surfactant-free dip coating

Large-scale production of reliable carbon nanotubes (CNTs) based gas sensors involves the development of scalable and reliable processes for the fabrication of films with controlled morphology. Here, we report for the first time on highly scalable, ultrathin CNT films, to be employed as conductometric sensors for NO2 and NH3 detection at room temperature. The sensing films are produced by dip coating using dissolved CNTs in chlorosulfonic acid as a working solution. This surfactant-free approach does not require any post-treatment for the removal of dispersants or any CNTs functionalization, thus promising high quality CNTs for better sensitivity and low production costs. The effect of CNT film thickness and defect density on the gas sensing properties has been investigated. Detection limits of 1 ppm for NO2 and 7 ppm for NH3 have been achieved at room temperature. The experimental results reveal that defect density and film thickness can be controlled to optimize the sensing response. Gas desorption has been accelerated by continuous in-situ UV irradiation.

Ethical values and the global carbon integrity system

There are many excellent books on climate justice and ethics, and their theorizing is a crucial and natural step in moving towards a justified response to this urgent problem. However, the purpose of this book lies elsewhere; it explores how ethical values can and should work in driving and structuring the global carbon integrity system.

Turnover intentions of employees with informal eldercare responsibilities: The role of core self-evaluations and supervisor support

As longevity increases, so does the need for care of older relatives by working family members. This research examined the interactive effect of core self-evaluations and supervisor support on turnover intentions in two samples of employees with informal caregiving responsibilities. Data were obtained from 57 employees from Australia (Study 1) and 66 employees from the United States and India (Study 2). Results of Study 1 revealed a resource compensation effect, that is, an inverse relationship between core self-evaluations and turnover intentions when supervisor care support was low. Results of Study 2 extended these findings by demonstrating resource boosting effects. Specifically, there was an inverse relationship between core self-evaluations and subsequent turnover intentions for those with high supervisor work and care support. In addition, employees' satisfaction and emotional exhaustion from their work mediated the inverse relationship between core self-evaluations and subsequent turnover intentions when supervisor work support and care support were high. Overall, these findings highlight the importance of employee- and supervisor-focused intervention strategies in organizations to support informal caregivers.

From spent Mg/Al layered double hydroxide to porous carbon materials

Adsorption has been considered as an efficient method for the treatment of dye effluents, but properdisposal of the spent adsorbents is still a challenge. This work attempts to provide a facile methodto reutilize the spent Mg/Al layered double hydroxide (Mg/Al-LDH) after the adsorption of orange II(OII). Herein, the spent hybrid was carbonized under the protection of nitrogen, and then washedwith acid to obtain porous carbon materials. Thermogravimetric analysis results suggested that thecarbonization could be well achieved above 600◦C, as mass loss of the spent hybrid gradually stabilized. Therefore, the carbonization process was carried out at 600, 800, and 1000 ◦C, respectively. Scanning electron microscope showed that the obtained carbon materials possessed a crooked flaky morphology. Nitrogen adsorption–desorption results showed that the carbon materials had large BET surface area and pore volume, e.g., 1426 m2/g and 1.67 cm3/g for the sample carbonized at 800 ◦C. Moreover, the pore structure and surface chemistry compositions were tunable, as they were sensitive to the temperature. Toluene adsorption results demonstrated that the carbon materials had high efficiency in toluene removal. This work provided a facile approach for synthesizing porous carbon materials using spent Mg/Al-LDH.

Reducing age bias and turnover intentions by enhancing intergenerational contact quality in the workplace: The role of opportunities for generativity and development

Based on socio-emotional selectivity and self-categorization theories, we developed and tested a model on how the interplay between employee age and opportunities for generativity and development predicts age bias and turnover intentions via intergenerational contact quality in the workplace. We hypothesized indirect effects of opportunities for generativity on outcomes through intergenerational contact quality among older workers only, whereas we expected that the indirect effects of opportunities for development are stronger for young compared with older workers. Data came from 321 employees in Belgium who responded to an online questionnaire. Results showed that age moderated the relationships of opportunities for generativity and development with intergenerational contact quality consistent with the expected patterns. Furthermore, age moderated the indirect effects of opportunities for generativity and development on age bias through intergenerational contact quality, but not on turnover intentions. Implications for future research and practical suggestions for managing intergenerational contact at work are discussed.

Carbon-based silicon nanohybrid anode materials for rechargeable lithium ion batteries

Silicon has demonstrated great potential as anode materials for next-generation high-energy density rechargeable lithium ion batteries. However, its poor mechanical integrity needs to be improved to achieve the required cycling stability. Nano-structured silicon has been used to prevent the mechanical failure caused by large volume expansion of silicon. Unfortunately, pristine silicon nanostructures still suffer from quick capacity decay due to several reasons, such as formation of solid electrolyte interphase, poor electrical contact and agglomeration of nanostructures. Recently, increasing attention has been paid to exploring the possibilities of hybridization with carbonaceous nanostructures to solve these problems. In this review, the recent advances in the design of carbon-silicon nanohybrid anodes and existing challenges for the development of high-performance lithium battery anodes are briefly discussed.

Synthesis and applications of carbon nanomaterials for energy generation and storage

The world is facing an energy crisis due to exponential population growth and limited availability of fossil fuels. Over the last 20 years, carbon, one of the most abundant materials found on earth, and its allotrope forms such as fullerenes, carbon nanotubes and graphene have been proposed as sources of energy generation and storage because of their extraordinary properties and ease of production. Various approaches for the synthesis and incorporation of carbon nanomaterials in organic photovoltaics and supercapacitors have been reviewed and discussed in this work, highlighting their benefits as compared to other materials commonly used in these devices. The use of fullerenes, carbon nanotubes and graphene in organic photovoltaics and supercapacitors is described in detail, explaining how their remarkable properties can enhance the efficiency of solar cells and energy storage in supercapacitors. Fullerenes, carbon nanotubes and graphene have all been included in solar cells with interesting results, although a number of problems are still to be overcome in order to achieve high efficiency and stability. However, the flexibility and the low cost of these materials provide the opportunity for many applications such as wearable and disposable electronics or mobile charging. The application of carbon nanotubes and graphene to supercapacitors is also discussed and reviewed in this work. Carbon nanotubes, in combination with graphene, can create a more porous film with extraordinary capacitive performance, paving the way to many practical applications from mobile phones to electric cars. In conclusion, we show that carbon nanomaterials, developed by inexpensive synthesis and process methods such as printing and roll-to-roll techniques, are ideal for the development of flexible devices for energy generation and storage – the key to the portable electronics of the future.