Renewable energy and sustainable development are widely discussed and highly debated topics. The current and majority opinion is that for sustainable development renewable energy is a necessity and ...plenty of it is available, which can be harvested economically and in environment friendly way. There are also dissenters who feel strongly that fossil fuels are far from exhausted, can be used with clean technologies, which are already developed, while technical problems for renewable energy are far from solved and they are very often more damaging to the environment and society than envisaged. The phenomena of global warming and carbon dioxide build-up are also inseparably entangled with sustainability and energy. Most analyses take a short-term view, hardly ever beyond 2050 or 2100. We certainly expect the society to survive and remain viable well beyond these dates and therefore need to explore what such long-term sustainability may imply. So it seems appropriate to consider a much longer time span and in order to keep the discussion from becoming speculative, certain restrictions need to be imposed. Therefore, a concept of sustainability steady state is proposed. Rough analysis presented here based on data that are commonly accepted, and mass and energy conservation principle with second law, seem to indicate that irrespective of correlation between carbon dioxide build-up and global warming, renewable energy, specifically direct solar energy will have to be adopted. This will of course have to be aided by judicious amount of indirect solar energy like wind energy and particularly bio-energy. Renewable sources, while having orders of magnitude greater energy content than human society may use up, are not particularly easy to harness, allowing only a small part to be finally harvestable. There are tough technical, environmental and societal problems, all quite significant, that have to be solved and restrictions on its transmission and location of usage have to be followed. It will also require development of “wasteless technology” and recovery and recycle of materials, particularly those which are difficult to win from natural sources and may be in short supply. Thus, in the long run, “renewable energy” will become inevitable, but even this will require a great deal of effort and planning and will not come easy.
Graphical abstract
Reciprocating motion is a widely existing form of mechanical motion in natural environment. In this work we reported a case-encapsulated triboelectric nanogenerator (cTENG) based on sliding ...electrification to convert reciprocating motion into electric energy. Patterned with multiple sets of grating electrodes and lubricated with polytetrafluoroethylene (PTFE) nanoparticles, the cTENG exported an average effective output power of 12.2 mW over 140 kΩ external load at a sliding velocity of 1 m/s, in corresponding to a power density of 1.36 W/m2. The sliding motion can be induced by direct-applied forces as well as inertia forces, enabling the applicability of the cTENG in addressing ambient vibration motions that feature large amplitude and low frequency. The cTENG was demonstrated to effectively harvest energy from human body motions and wavy water surface, indicating promising prospects of the cTENG in applications such as portable and stand-alone self-powered electronics.
In a phase 3 trial involving more than 15,000 participants, two doses of NVX-CoV2373, a recombinant SARS-CoV-2 nanoparticle vaccine, administered 21 days apart had a vaccine efficacy of 89.7%. ...Reactogenicity was generally mild and transient, and adverse events were infrequent and of low grade.
Recently, commercial graphite and other carbon‐based materials have shown promising properties as the anode for potassium‐ion batteries. A fundamental problem related to those carbon electrodes, ...significant volume expansion, and structural instability/collapsing caused by cyclic K‐ion intercalation, remains unsolved and severely limits further development and applications of K‐ion batteries. Here, a multiwalled hierarchical carbon nanotube (HCNT) is reported to address the issue, and a reversible specific capacity of 232 mAh g−1, excellent rate capability, and cycling stability for 500 cycles are achieved. The key structure of the HCNTs consists of an inner CNT with dense‐stacked graphitic walls and a loose‐stacked outer CNT with more disordered walls, and individual HCNTs are further interconnected into a hyperporous bulk sponge with huge macropore volume, high conductivity, and tunable modulus. It is discovered that the inner dense‐CNT serves as a robust skeleton, and collectively, the outer loose‐CNT is beneficial for K‐ion accommodation; meanwhile the hyperporous sponge facilitates reaction kinetics and offers stable surface capacitive behavior. The hierarchical carbon nanotube structure has great potential in developing high‐performance and stable‐structure electrodes for next generation K and other metal‐ion batteries.
A hierarchical carbon nanotube (HCNT) consists of two coaxial, seamless arranged parts, including a dense‐stacked inner CNT and a loose‐stacked outer CNT. Those HCNTs are interconnected into a hyperporous bulk sponge with a huge macropore volume, high conductivity, and tunable modulus. Such unique materials have potential applications as high‐performance freestanding anodes for K‐ion batteries with excellent specific capacity and cycling stability.
Freestanding composite structures with embedded transition metal dichalcogenides (TMDCs) as the active material are highly attractive in the development of advanced electrodes for energy storage ...devices. Most 3D electrodes consist of a bilayer design involving a core–shell combination. To further enhance the gravimetric and areal capacities, a 3D trilayer design is proposed that has MoSe2 as the TMDC sandwiched in‐between an inner carbon nanotube (CNT) core and an outer carbon layer to form a CNT/MoSe2/C framework. The CNT core creates interconnected pathways for the e−/Na+ conduction, while the conductive inert carbon layer not only protects the corrosive environment between the electrolyte and MoSe2 but also is fully tunable for an optimized Na+ storage. This unique heterostructure is synthesized via a solvothermal‐carbonization approach. Due to annealing under a confined structural configuration, MoSe2 interlayer spaces are expanded to facilitate a faster Na+ diffusion. It is shown that an ≈3 nm thick carbon layer yielded an optimized anode for a sodium‐ion battery. The 3D porosity of the heterostructure remains intact after an intense densification process to produce a high areal capacity of 4.0 mAh cm−2 and a high mass loading of 13.9 mg cm−2 with a gravimetric capacity of 347 mAh g−1 at 500 mA g−1 after 500 cycles.
A 3D trilayer heterostructure (3D CNT/MoSe2/C) (CNT: carbon nanotube) is fabricated in which expanded MoSe2 is sandwiched in‐between the carbon nanotube and the carbon layer with a tunable thickness of outer carbon layer. The 3D CNT/MoSe2/C heterostructures are highly porous and can be densified by compaction. Representative CNT/MoSe2/C present adequately high mass loading, high areal capacity, and excellent cyclic stability for sodium‐ion batteries.
Osteoarthritis (OA) is the most prevalent and debilitating joint disease, and there are currently no effective disease-modifying treatments available. Multiple risk factors for OA, such as aging, ...result in progressive damage and loss of articular cartilage. Autonomous circadian clocks have been identified in mouse cartilage, and environmental disruption of circadian rhythms in mice predisposes animals to OA-like damage. However, the contribution of the cartilage clock mechanisms to the maintenance of tissue homeostasis is still unclear. Here, we have shown that expression of the core clock transcription factor BMAL1 is disrupted in human OA cartilage and in aged mouse cartilage. Furthermore, targeted Bmal1 ablation in mouse chondrocytes abolished their circadian rhythm and caused progressive degeneration of articular cartilage. We determined that BMAL1 directs the circadian expression of many genes implicated in cartilage homeostasis, including those involved in catabolic, anabolic, and apoptotic pathways. Loss of BMAL1 reduced the levels of phosphorylated SMAD2/3 (p-SMAD2/3) and NFATC2 and decreased expression of the major matrix-related genes Sox9, Acan, and Col2a1, but increased p-SMAD1/5 levels. Together, these results define a regulatory mechanism that links chondrocyte BMAL1 to the maintenance and repair of cartilage and suggest that circadian rhythm disruption is a risk factor for joint diseases such as OA.
The human oropharynx is a reservoir for many potential pathogens, including streptococcal species that cause endocarditis. Although oropharyngeal microbes have been well described, viral communities ...are essentially uncharacterized. We conducted a metagenomic study to determine the composition of oropharyngeal DNA viral communities (both phage and eukaryotic viruses) in healthy individuals and to evaluate oropharyngeal swabs as a rapid method for viral detection. Viral DNA was extracted from 19 pooled oropharyngeal swabs and sequenced. Viral communities consisted almost exclusively of phage, and complete genomes of several phage were recovered, including Escherichia coli phage T3, Propionibacterium acnes phage PA6, and Streptococcus mitis phage SM1. Phage relative abundances changed dramatically depending on whether samples were chloroform treated or filtered to remove microbial contamination. pblA and pblB genes of phage SM1 were detected in the metagenomes. pblA and pblB mediate the attachment of S. mitis to platelets and play a significant role in S. mitis virulence in the endocardium, but have never previously been detected in the oral cavity. These genes were also identified in salivary metagenomes from three individuals at three time points and in individual saliva samples by PCR. Additionally, we demonstrate that phage SM1 can be induced by commonly ingested substances. Our results indicate that the oral cavity is a reservoir for pblA and pblB genes and for phage SM1 itself. Further studies will determine the association between pblA and pblB genes in the oral cavity and the risk of endocarditis.
Neutron stars are not only of astrophysical interest, but are also of great interest to nuclear physicists because their attributes can be used to determine the properties of the dense matter in ...their cores. One of the most informative approaches for determining the equation of state (EoS) of this dense matter is to measure both a star's equatorial circumferential radius Re and its gravitational mass M. Here we report estimates of the mass and radius of the isolated 205.53 Hz millisecond pulsar PSR J0030+0451 obtained using a Bayesian inference approach to analyze its energy-dependent thermal X-ray waveform, which was observed using the Neutron Star Interior Composition Explorer (NICER). This approach is thought to be less subject to systematic errors than other approaches for estimating neutron star radii. We explored a variety of emission patterns on the stellar surface. Our best-fit model has three oval, uniform-temperature emitting spots and provides an excellent description of the pulse waveform observed using NICER. The radius and mass estimates given by this model are km and (68%). The independent analysis reported in the companion paper by Riley et al. explores different emitting spot models, but finds spot shapes and locations and estimates of Re and M that are consistent with those found in this work. We show that our measurements of Re and M for PSR J0030+0451 improve the astrophysical constraints on the EoS of cold, catalyzed matter above nuclear saturation density.
PDF
