Heterogeneous Single Atom Electrocatalysis,Where “Singles” Are “Married”

There is an intensive search for heterogeneous single atom catalysts (SACs) of high activity, efficiency, durability, and selectivity for a wide variety of electrocatalytic conversion and chemical reactions, such as the hydrogen evolution reaction (HER), oxygen evolution/reduction reaction (OER and ORR), CO₂ reduction reaction (CO₂ RR), and nitrogen reduction reaction (NRR). With the downsizing from nanoparticles and clusters to single atoms, there are steady changes in the bond and coordination environment for each and every atom involved. Indeed, the single atoms in these electrocatalysts are not “singles”; they are “married” to the supporting surfaces, and their performance is controlled by the bonding and coordination with the substrate surfaces. Herein, an overview is presented on the brief history leading to the rapid development of SACs and their current status, by focusing on their synthesis, control of composition, strategies to realize single atoms with the desired bonds and coordination, and targeted performance in selected reactions. Their applications in the selected spectrum of energy conversion and chemical reactions are discussed, in relation to their structures at varying length scales down to the atomic level. A particular emphasis is placed on on‐going research activities, together with the future perspectives and particular challenges for SACs.     

Initiation,calcification, and form of larval “archaeogastropod” shells

The coiled shell of gastropods begins as a cap-shaped lens of organic and calcified material that covers the posterior dorsal side of the larva. During development the cap enlarges to cover the larval visceral mass. Marginal growth then produces the characteristic coiled shell. One model of the initiation of shell coiling in “archaeogastropods” requires that the shell remains flexible and uncalcified until after torsion, and that muscle contraction during torsion deforms the shell. We describe early shell calcification and tested this requirement of the model for the patellogastropod limpets Tectura scutum and Lottia digitalis, the trochids Calliostoma ligatum and Margarites pupillus and the abalone Haliotis kamtschatkana. We determined the stage of initial calcification by staining larvae with the fluorescent calcium marker calcein and observing them with bright field, crossed polarizing filter, and fluorescence microscopy. In T. scutum the earliest observable shell was calcified and calcium was sometimes detected even before the initial shell was visible. Larvae of the other species deposited a noncalcified matrix that was subsequently calcified, and in C. ligatum and M. pupillus this initial calcification was distinctly spotty. Shells of both patellogastropods and the abalone were demonstrably rigid prior to torsion while the shells of the trochids were not. These results suggest that shell coiling in patellogastropods and abalone is not initiated by contraction of the larval retractor muscle during torsion; in trochids this mechanism is possible. However, analysis of camera lucida drawings of pre- and post-torsional shells of T. scutum and C. ligatum did not detect shell shape changes during torsion. J. Morphol. 235:77–89, 1998. © 1998 Wiley-Liss, Inc.     

“Right” or “wrong”? insights into the ecology of sidedness in european flounder,Platichthys flesus

Sidedness polymorphism in flatfish has been linked to ecological selection between morphs. However, the alternate hypothesis that morphological differences between right‐ and left‐sided forms may be due to errors during development, as a consequence of disturbed homeostasis, which still remains largely unexplored. Here, we examined the case of Platichthys flesus (flounder), a polymorphic flatfish exhibiting large and clinal variation in the frequency of the left‐sided morph, which is the reversed condition in this generally right‐sided species. An integrated approach consisting of the analyses of shape variation, stomach contents, and skeletal anomalies was used. Morphological differences were observed between morphs, which are in agreement with previous findings in a congeneric species (Platichthys stellatus). In parallel, significant differences in feeding choices were detected, suggesting a coherent association between subtle morphological differences between morphs and their use of trophic resources. Skeletal anomalies and meristic counts did not corroborate the hypothesis that morphometric divergence in reversed individuals may be caused or reinforced by developmental instability. J. Morphol. 2012. © 2011 Wiley Periodicals, Inc.     

Preliminary Observations on the Nature,Taxonomic Composition,Distribution, Behaviour and Nutrient Requirements of the “Unusual” Algal “Jellies” of Oguta Lake in Southeastern Nigeria

Preliminary observations were made between October 1982 and May 1983 on the nature, taxonomic composition, spatial distribution, buoyancy behaviour and nutrient requirements of some unusual planktonic algal “jellies” in Oguta Lake in Southeastern Nigeria. These “jellies” are macroscopic, blue-green algal masses whose excessive mucilage of high consistency acts as substrata for other epiphytic components viz. diatoms and green algae. They are more abundant in the lentic areas of the lake, undergo diurnal vertical movements and have their growth enhanced by spikes of nitrogen and phosphorus salts into their aquatic medium. The effects of these “jellies” on the ecology and general water use of the lake are discussed. Speculations on the reasons for their occurrence are given and possible control measures outlined.     

Teilhard de Chardin,human evolution and “Piltdown Man”

Pierre Teilhard de Chardin was a French Jesuit paleontologist, priest, and philosopher. In the figures published in articles in 1943 and 1951, he attempted to draw a “plausible schematic reconstruction of the natural connections between fossil men” and a “phyletic composition of the human group”. I draw attention to Teilhard's reference to Eoanthropus (“Piltdown Man”) in small print in his figure that was first printed in 1943. Most suspiciously, there is no reference to this (supposedly important) genus in the associated text, nor is there any reference whatsoever to “Piltdown Man” in the article published in 1951. Even as early as January 1913, Teilhard may have been aware that “Piltdown Man” was a hoax or joke, artificially associating a human cranium with a modified orangutan mandible. A new suspect is Edgar Willett (rather than Charles Dawson). Teilhard may have been an advisory accomplice in a joke that went seriously wrong.     

“Inflammatory” Cytokines

If cytokines are constitutively expressed by and act on neurons in normal adult brain, then we may have to modify our current view that they are predominantly inflammatory mediators. We critically reviewed the literature to determine whether we could find experimental basis for such a modification. We focused on two "proinflammatory" cytokines, interleukin (IL)-1 and tumor necrosis factor-alpha (TNFalpha) because they have been most thoroughly investigated in shaping our current thinking. Evidence, although equivocal, indicates that the genes coding for these cytokines and their accessory proteins are expressed by neurons, in addition to glial cells, in normal brain. Their expression is region- and cell type-specific. Furthermore, bioactive cytokines have been extracted from various regions of normal brain. The cytokines' receptors selectively are present on all neural cell types, rendering them responsive to cytokine signaling. Blocking their action modifies multiple neural "housekeeping" functions. For example, blocking IL-1 or TNFalpha by several independent means alters regulation of sleep. This indicates that these cytokines likely modulate in the brain behavior of a normal organism. In addition, these cytokines are likely involved in synaptic plasticity, neural transmission, and Ca2+ signaling. Thus, the evidence strongly suggests that these cytokines perform neural functions in normal brain. We therefore propose that they should be thought of as neuromodulators in addition to inflammatory mediators.     

Hierarchically Porous,Ultrathick, “Breathable” Wood‐Derived Cathode for Lithium‐Oxygen Batteries

In this work, a hierarchically porous and ultrathick “breathable” wood‐based cathode for high‐performance Li‐O₂ batteries is developed. The 3D carbon matrix obtained from the carbonized and activated wood (denoted as CA‐wood) serves as a superconductive current collector and an ideal porous host for accommodating catalysts. The ruthenium (Ru) nanoparticles are uniformly anchored on the porous wall of the aligned microchannels (denoted as CA‐wood/Ru). The aligned open microchannels inside the carbon matrix contribute to unimpeded oxygen gas diffusion. Moreover, the hierarchical pores on the microchannel walls can be facilely impregnated by electrolyte, forming a continuous supply of electrolyte. As a result, numerous ideal triphase active sites are formed where electrolyte, oxygen, and catalyst accumulate on the porous walls of microchannels. Benefiting from the numerous well‐balanced triple‐phase active sites, the assembled Li‐O₂ battery with the CA‐wood/Ru cathode (thickness: ≈700 µm) shows a high specific area capacity of 8.58 mA h cm^?2 at 0.1 mA cm^?2. Moreover, the areal capacity can be further increased to 56.0 mA h cm^?2 by using an ultrathick CA‐wood/Ru cathode with a thickness of ≈3.4 mm. The facile ultrathick wood‐based cathodes can be applied to other cathodes to achieve a super high areal capacity without sacrificing the electrochemical performance.