Molecular basis of Arginine and Lysine DNA sequence-dependent thermo-stability modulation

We have used a variety of theoretical and experimental techniques to study the role of four basic amino acids–Arginine, Lysine, Ornithine and L-2,4-Diaminobutyric acid–on the structure, flexibility and sequence-dependent stability of DNA. We found that the presence of organic ions stabilizes the duplexes and significantly reduces the difference in stability between AT- and GC-rich duplexes with respect to the control conditions. This suggests that these amino acids, ingredients of the primordial soup during abiogenesis, could have helped to equalize the stability of AT- and GC-rich DNA oligomers, facilitating a general non-catalysed self-replication of DNA. Experiments and simulations demonstrate that organic ions have an effect that goes beyond the general electrostatic screening, involving specific interactions along the grooves of the double helix. We conclude that organic ions, largely ignored in the DNA world, should be reconsidered as crucial structural elements far from mimics of small inorganic cations.

Reading M87's DNA: A Double Helix Revealing a Large-scale Helical Magnetic Field

We present unprecedented high-fidelity radio images of the M87 jet. We analyzed Jansky Very Large Array broadband full-polarization radio data from 4 to 18 GHz. The observations were taken with the most extended configuration (A configuration), which allows the study of the emission of the jet up to kiloparsec scales with a linear resolution of ∼10 pc. The high sensitivity and resolution of our data allow us to resolve the jet width. We confirm a double-helix morphology of the jet material between ∼300 pc and ∼1 kpc. We found a gradient of the polarization degree with a minimum at the projected axis and maxima at the jet edges and a gradient in the Faraday depth with opposite signs at the jet edges. We also found that the behavior of the polarization properties along the wide range of frequencies is consistent with internal Faraday depolarization. All of these characteristics strongly support the presence of a helical magnetic field in the M87 jet up to 1 kpc from the central black hole, although the jet is most likely particle-dominated at these large scales. Therefore, we propose a plausible scenario in which the helical configuration of the magnetic field has been maintained to large scales thanks to the presence of Kelvin–Helmholtz instabilities.

Visualization in the Ranque-Hilsch vortex tube using high-speed video recording

Visualisation via video recording was carryed out in a Ranque-Hilsch vortex tube with a square cross-section. Video files were captured at recording speeds from 1000 to 10 000 frames per second. The best video files were obtained at a shooting frequency of 7600 frames per second with an input pressure of 1 bar. The video confirmed the presence of a double helix in the flow core in the second section of the tube. The video files showed the presence of a circulation zone between the flow core and the periphery, which is constantly changing over time. It can be clearly seen the angle at which the particles move in the peripheral flow.

Degenerate topological line surface phonons in quasi-1D double helix crystal SnIP

Degenerate points/lines in the band structures of crystals have become a staple of the growing number of topological materials. The bulk-boundary correspondence provides a relation between bulk topology and surface states. While line degeneracies of bulk excitations have been extensively characterised, line degeneracies of surface states are not well understood. We show that SnIP, a quasi-one-dimensional van der Waals material with a double helix crystal structure, exhibits topological nodal rings/lines in both the bulk phonon modes and their corresponding surface states. Using a combination of first-principles calculations, symmetry-based indicator theories and Zak phase analysis, we find that two neighbouring bulk nodal rings form doubly degenerate lines in their drumhead-like surface states, which are protected by the combination of time-reversal symmetry $${{{\mathcal{T}}}}$$ T and glide mirror symmetry $${\bar{M}}_{y}$$ M ¯ y . Our results indicate that surface degeneracies can be generically protected by symmetries such as $${{{\mathcal{T}}}}{\bar{M}}_{y}$$ T M ¯ y , and phonons provide an ideal platform to explore such degeneracies.

Coupled Schrödinger equations as a model of interchain torsional excitation transport in the DNA model

In this report we consider two weakly coupled Schrödinger equations as a model of interchain energy transport in the DNA double-helix. We employ a reduction of the Yakushevich-type model that considers the torsional dynamics of the DNA. In previous works, only small amplitude excitations and stationary dynamics were investigated, whereas we focus on the nonstationary dynamics of the double helix. In this report we consider two weakly coupled Schrödinger equations as a reduced model of interchain energy transport in the DNA double-helix torsional model. We employ a reduction of the Yakushevich-type model that considers the torsional dynamics of the DNA as effective chains of pendula. In previous works, only small amplitude excitations and stationary dynamics were investigated, whereas we focus on the nonstationary dynamics of the double helix. We consider the system to be a model of two weakly interacting DNA strands. Assuming that initially only one of the chains is excited in the form of a breather, we demonstrate the existence of an invariant that allows us to reduce the order of the problem and examine the system of the phase plane. The analysis demonstrates the utility of an analytical tool for predicting the periodic interchain excitation transitions of its localisation on one of the chains. The technique also takes into account the spreading of the excitations over time.

The History and Challenges of Women in Genetics: A Focus on Non-Western Women

“Women in much of the world lack support for fundamental functions of a human life.” This truthful portrait was pointed out by Martha Nussbaum in her book “Introduction: Feminism & International Development.” Throughout history, gender inequality has been persistent in many aspects of life, including health and empowerment. Unfortunately, this inequality has not been excluded from the field of science. Perpetual assumption that women’s absence or restriction to secondary roles in various disciplines is an acceptable law of nature misrepresents women’s contribution to science and maintains hurdles for participation in the future. According to a recent UNESCO’s report, women make up only 30% of researchers worldwide. But despite all the obstacles, women made major contributions with discoveries that shaped the progress in many scientific fields. In the field of genetics, Rosalind Franklin is an example of unwittingly compromised women’s scientific achievements. Franklin was an expert in X-ray crystallography; her data, especially the “photo 51,” was critical to James Watson and Francis Crick along with their own data to publish the discovery of the double helix DNA structure in 1953. Her contribution was acknowledged posthumously in Watson’s memoir in 1968. Barbara McClintock was a 20th century American cytogeneticist who remains up to date the only woman receiving an unshared Nobel prize in Physiology or Medicine. McClintock dedicated her work to cytogenetics and discovered the phenomenon of mobile genes. Her research was initially subjected to skepticism in the 1950s. It was not until the late 1960s that the community realized the significance of McClintock’s discovery. The history of science is occupied with a myriad of similar tales of such inspiring women that, after tremendous struggles, thrived and achieved breakthroughs in their respective fields. It is prominent our limited knowledge of women’s experience and struggle in science in non-western world. Addressing the stories of this outstanding minority is critical to expand the understanding of the gender disparity factors embedded in diverse cultures. In this article, we attempt to put the spotlight on some fascinating non-western women and their significant contributions to the field of genetics.

Research on Knowledge Creation and Knowledge Diffusion Mechanism of Industry University Research Cooperation Model —Take the Tobacco Industry ASAN Example

Knowledge creation is an important basis of national innovation strategy, and industry university research cooperation is an important way of knowledge creation. Exploring the knowledge diffusion mechanism of different industry university research cooperation modes is conducive to knowledge creation. A good knowledge creation mechanism can improve the level of knowledge creation. Taking the tobacco industry as an example, this paper improves the knowledge creation level of the tobacco industry by establishing the knowledge creation mechanism of the tobacco industry, so as to solve the technical bottleneck of the tobacco industry and increase the number of innovative products in the tobacco industry. Through combing the research of scholars, it is found that the research on the promotion of knowledge creation by industry university research cooperation mode is relatively rich, but the research from the perspective of the relationship between knowledge diffusion mechanism and knowledge creation mechanism is slightly insufficient. In order to improve the knowledge creation level of industry university research cooperation, this paper obtains the knowledge creation mechanism of different industry university research cooperation modes by using SECI knowledge creation model. Innovatively put forward the "double helix" relationship between knowledge creation and knowledge diffusion in industry university research cooperation, that is, the knowledge diffusion mechanism in different industry university research cooperation modes will affect the level of knowledge creation, which provides a theoretical basis for the main subject of industry university research cooperation to find a way to improve the level of industry university research cooperation.