Interfacial electron transfer constitutes the key step in the conversion of solar energy into electricity and fuels. Required for fast and efficient charge separation, strong donor−acceptor interaction is typically achieved through covalent chemical bonding…or not. Experiences with donor−acceptor molecular diads and triads, conjugated polymers, and DNA, leads to the expectation that a covalent bonding is […]
Testosterone is the primary male sex hormone and, in men, it plays a key role in the development of male reproductive tissues such as the testis and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair. Testosterone increases in heterosexual men after having […]
Extended and refined by Bloch and others during the 1930s, Bloch’s theory, known as the band theory of solids, accounts very well for the conducting behaviour of materials. When atoms are joined together into a crystal, each of the individual quantum states of the atoms joins with the corresponding states in other (identical) atoms in […]
We’ve known for decades there was a time when mammoths, saber-tooth cats, and other big mammals walked the Earth like it was no big deal. We also know that at some point of the Ice Age, a mass extinction made them disappear, leaving their fossils and their descendants as the only proof of their existence […]
Topological insulators are electronic materials that have a bulk band gap like an ordinary insulator but have conducting states on their edge or surface. The conducting surface is not what makes topological insulators unique, but the fact that it is protected due to the combination of spin-orbit interactions and time-reversal symmetry. Researchers are chasing efficient […]
Reference contains the following statement: “Ashtekar’s formulation of general relativity taught us to think of gravitational theories as theories of connections, on a bare manifold with no metric structure. […] The idea that general relativity has its deepest formulation as a connection theory suggested immediately a new approach to the unification of general relativity with […]
For centuries, metals were employed in optical applications only as mirrors and gratings. New vistas opened up in the late 1970s and early 1980s with the discovery of surface-enhanced Raman scattering and the use of surface plasmon (collective electronic oscillations at the surface of metals) resonances for sensing. However, it was not until the 1990s […]
When we talk about nucleic acids we generally think of DNA and RNA that code for proteins, and when we talk about brain cells we tend to think of neurons and their nerve impulse transmission. However, it is not news that the functions of both non-coding genetic material and non-transmitting cells in the brain are […]
Over geologic time scales, seawater transforms the basalt of the ocean floor by chemical attack. At the end of this alteration process, the basalt turns partly into clays and partly into dissolved salts in sea water. Lithium, a chemical element initially contained in basalt, will then be distributed between clay and seawater. This separation has […]
Syphilis is a sexually transmitted disease caused by a spirochete, a bacterium, Treponema pallidum subspecies pallidum . The main route of infection is by sexual contact but is also transmitted from the mother to the newborn in what is known as congenital syphilis. If syphilis is left untreated for years the treponema may invade the […]