The ribosome is responsible for protein synthesis in all living organisms. It is best known to exist around 3.5–3.7 Ga whereat life on Earth inhabited anoxic environment with abundant soluble irons. The RNAs and proteins are the two biopolymers that constitute the ribosome. However, both proteins and RNAs require metal cations to fold and to function. There are four Mg-microcluster (Mg
2+
-μc) structures conserved in core of large subunit, and the 23S ribosomal RNA (rRNA) was shown to catalyze electron transfer in an anoxic environment in the presence of Fe
2+
. The Mg
2+
-μc features two idiosyncratic Mg
2+
ions that are chelated and bridged by a common phosphate group and along with that, the adjacent residues of RNA backbone together forming ten-membered chelation ring(s). Here, we utilized four rRNA fragments of the large subunit 23S rRNA of
Haloarcula marismortui
, that includes the residues that form the four Mg
2+
-μc’s. These four rRNA fragments are shown competent to assemble with Mg
2+
. Our results show that when these rRNA fragments fold or assembly in the presence of Fe
2+
under anoxic conditions, each Fe
2+
-microcluster can catalyze electron transfer. We propose that Fe
2+
-microclusters of the ribosome, which use Fe
2+
as a cofactor to regulate electron transfer, are pivotal and primordial and may be an origin in evolution of the ribosome.
Bullying is a widespread phenomenon, occurring in many countries; however, until recently, knowledge of it was limited due to the lack of access to information. Also, most parents of K-12 students failed to see it as an important issue. Now, it is widely agreed upon that bullying is common and detrimental. Use of media outlets to disseminate this message is helping to gradually chip away at this previously ignored problem. Hence, bullying behavior is difficult to detect immediately and prevent. This study uses a simulation model based on the social impact theory to study the changing roles of a class of 40 students during a semester long period. The students in the class were divided into three roles: the bullies, the victims and the bystanders. The model also defines a new criterion, the ''bullying index,'' designed to shed light on the underlying dynamics of bullying through experimental design. Regression results show that the percentage of students bullied in school lessened significantly when the environment changed. The parental and persuasiveness constants were significant, while the impact of counseling was not, even after intensive counseling. This means that we should separate bullies', bystanders' and victims' education to prevent bullying behaviors.
Hg-based chalcogenides possess diverse structures, large
nonlinear-optical
(NLO) responses, and suitable birefringences, making them potentially
suitable for numerous crucial criteria of practical application as
infrared (IR) NLO crystals. Here, a new pentanary Hg-based sulfide
K2Ba7HgIn4S16 has been
discovered by a high-temperature solid-state method. It crystallizes
in the orthorhombic P21212
space group, and its one-dimensional structure is constructed by {[In2S7]8–}∞ chains
and isolated [HgS4]6– planar quadrilateral
units located bewteeen the chains, representing a novel type of chalcogenide.
K2Ba7HgIn4S16 exhibits
a moderate NLO effect of 0.5 × AGS at 2.1 μm and a high
laser-induced damage threshold of ∼5.8 × AGS, as well
as a band gap of 2.98 eV, demonstrating that K2Ba7HgIn4S16 is a potential IR NLO material. This
work enriches the structural chemistry of chalcogenides and the family
of Hg-based IR NLO chalcogenides.
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