Formamide and the origin of life

The complexity of life boils down to the definition: “self-sustained chemical system capable of undergoing Darwinian evolution” (Joyce, 1994) [1]. The term “self-sustained” implies a set of chemical reactions capable of harnessing energy from the environment, using it to carry out programmed anabolic and catabolic functions. We briefly present our opinion on the general validity of this definition.Running anabolic and catabolic functions entails complex chemical information whose stability, reproducibility and evolution constitute the core of what is dubbed genetics.Life as-we-know-it is made of the intimate interaction of metabolism and genetics, both built around the chemistry of the most common elements of the Universe (hydrogen, oxygen, nitrogen, carbon). Other elements like phosphorus and sulphur play important but ancillary and potentially replaceable roles.The reproducible interaction of metabolic and genetic cycles results in the hypercycles of organization and de-organization of chemical information that we consider living entities. In order to approach the problem of the origin of life it is therefore reasonable to start from the assumption that both metabolism and genetics had a common origin, shared a common chemical frame, were embedded in physical–chemical conditions favourable for the onset of both.The most abundant three-atoms organic compound in interstellar environment is hydrogen cyanide HCN, the most abundant three-atoms inorganic compound is water H₂O. The combination of the two results in the formation of formamide H₂NCOH. We have explored the chemistry of formamide in conditions compatible with the synthesis and the stability of compounds of potential pre-genetic and pre-metabolic interest. We discuss evidence showing (i) that all the compounds necessary for the build-up of nucleic acids are easily obtained abiotically, (ii) that essentially all the steps leading to the spontaneous generation of RNA are abiotically possible, (iii) that the key compounds of extant metabolic cycles are obtained in the same chemical frame, often in the same test tube.How close are these observations to a plausible scenario for the origin of life?     

Water as the fabric of life

Many share the feeling that we are at in the midst of a shift in our perception of water — a shift from the current molecular-level based approach (which focuses on the behaviour of individual or small numbers of molecules) towards a new, systemic view of water. In this new picture, water is perceived as an active substance that responds adaptively to external and internal constraints and signals. These responses can have profound effects on substances immersed in water, and in particular on the functioning of biological constituents, from molecules to living cells. This special volume presents some existing and possible future directions in this trend towards a systemic view of water as an active substance, which plays many essential roles in sustaining life. The work reported here suggests that the notion of water as “life’s solvent” should give way to the new realisation of water as an active “fabric of life”, continuously engaging and interacting with biomolecules in complex and subtle ways.     

Physics and the explanation of life

It is proposed to consider present-day physics as dealing with a special situation, the situation in which the phenomena of life and consciousness play no role. It is pointed out that physical theory has often dealt, in the past, with similarly special situations. Planetary theory neglects all but gravitational forces, macroscopic physics neglects fluctuations due to the atomic structure of matter, nuclear physics disregards weak and gravitational interactions. In some of these cases, physicists were well aware of dealing with special situations, or limiting cases as they are called in the article; in other cases, they were not. It is pointed out that, even if it were true that present-day physics accurately describes the motion of the physical constituents of living bodies, it would not give the whole story. Arguments are adduced, however, to show that the laws of physics, applicable for inanimate matter, will have to be modified when dealing with the more general situation in which life and consciousness play significant roles.The present article is a somewhat revised version of the address presented by the writer at the 1969 AAAS meeting in Boston, Mass.     

Observation of "Stick" and "Handle" intermediates along the fullerene road

The hypothesis that fullerenes grow in a carbon plasma by the addition of C2 units (the "fullerene road") has been widely acclaimed as the most plausible mechanism for formation of larger fullerenes including C60 and C70. Calculations suggest that the association of C2 with fullerenes proceeds through two classes of intermediates, "sticks" and "handles." Here we report the observation of these species using high-resolution ion-mobility measurements for C(n) cations generated by laser vaporization of graphite and laser desorption of C60. Sticks with up to eight-atom chains have also been found.     

Metastability of life

The physical idea of the natural origin of diseases and deaths has been presented. The fundamental microscopical reason is the destruction of any metastable state by thermal activation of a nucleus of a irreversible change. On the basis of this idea the quantitative theory of age dependence of the death probability has been constructed. The obtained simple Death Laws are very accurately fulfilled almost for all known diseases.     

Signs of life

Programmable electronic calculators provide a speedy means of performing scientific calculations, e.g. the evaluation of a given polynomial for many different x values and the performance of iterative procedures for the solution of polynomial equations. Both of these uses appear in variational calculations of the energy of simple quantum mechanical systems such as the perturbed harmonic oscillator. For this system the traditional perturbation method has some drawbacks, end so it is useful to find its energy levels directly by purely numerical methods. The electronic calculator can do this if the relevant Schrödinger differential equation is transformed into a difference equation. The diffusion equation is a partial differential equation, but can be converted to an ordinary differential equation and thence to a pair of difference equations which can be solved on the calculator. This applies even if the diffusion coefficient depends on the concentration, so that the associated ordinary differential equation is non-linear.     

Ccontrolling the Transition Between "Higher" and "Lower" State of OB in Coherent Atomic Medium

We present a new experimental demonstration that the threshold points and shape of OB hysteresis curve in a four-level Rb atomic system inside an optical cavity were controllably changed by optical signals.Tuning the triggering optical signal to two different transitions of the atomic system we found that the OB threshold points shift toward different direction and at the same time the shape of the OB curve is also changed.For a given intensity of probe laser the OB system can be reliably inversed from its lower stable state to upper state under the triggering of a suitably tuned optical pulse signal (we named it up-controlling signal).More interesting, the inversed OB state does not drop to its initial lower stable state after the triggering pulse signal has passed, but moves to the upper branch of the initial OB curve and stably stays there until another optical signal tuned on other atomic transition (named down-controlling signal) coming.The result shows that there is the ability of information storage in the OB system.The experiments are reasonably explained with the change of cavity resonant condition resulting from the enhanced third-order nonlinearity in multilevel atomic system owing to atomic coherence.     

On the concept of "tractor beams"

We demonstrate the existence of a class of optical beams where the nonconservative forces can be locally oriented in a direction opposite to the propagation wave vector. Objects placed in the vicinity of these locations will move toward the source of light. The behavior of these negative forces is discussed for the particular case of nondiffracting rotating scale-invariant vector electromagnetic waves.     

对"胡不归问题"的思考

从前，有一个小伙子在外地当学徒，当他获悉在家乡的年老父亲病危的消息后，便立即启程赶路．由于思念心切，他选择了全是砂砾地带的直线路径．当他气喘吁吁地赶到父亲眼前时，老人刚刚咽了气．小伙子不觉失声痛哭，邻舍劝慰小伙子说，老人在弥留之际还不断喃喃地叨念“胡不归？胡不归？”．对这个古老的传说，引起了人们很多的思索，小伙子要能稍早些到家，就不会出现这种遗憾了．