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Archive for the ‘chemistry’ category: Page 90

Apr 12, 2023

Rapid alternating polarity brings new life to 189-year-old electrochemical reaction

Posted by in categories: chemistry, materials

Nearly 200 years since its discovery, industry rarely uses the carbon–carbon bond-forming Kolbe reaction – but now US researchers have shown it can sustainably make valuable substances.

Phil Baran’s team at Scripps Research Institute in La Jolla has done away with high voltages and platinum electrodes best established in the Kolbe reaction. In doing so, the researchers have made it much more versatile. ‘The most important feature is the ability to take waste or similarly priced products convert them into extremely high value materials,’ Baran tells Chemistry World.

Apr 12, 2023

Stellar Revelation: AI Discovers the Universe’s First Stars Weren’t Alone

Posted by in categories: chemistry, cosmology, robotics/AI

Using artificial intelligence, an international team analyzed the chemical composition of extremely metal-poor stars, finding that the first stars in the Universe were likely born in groups rather than individually. This method will be applied to future observations to better understand the early Universe.

An international team has used artificial intelligence to analyze the chemical abundances of old stars and found indications that the very first stars in the Universe were born in groups rather than as isolated single stars. Now the team hopes to apply this method to new data from on-going and planned observation surveys to better understand the early days of the Universe.

After the Big Bang, the only elements in the Universe where hydrogen, helium, and lithium. Most of the other elements making up the world we see around us were produced by nuclear reactions in stars. Some elements are formed by nuclear fusion at the core of a star, and others form in the explosive supernova death of a star. Supernovae also play an important role in scattering the elements created by stars, so that they can be incorporated into the next generation of stars, planets, and possibly even living creatures.

Apr 11, 2023

Multiscale quantum algorithms for quantum chemistry

Posted by in categories: chemistry, computing, information science, quantum physics

As quantum advantage has been demonstrated on different quantum computing platforms using Gaussian boson sampling,1–3 quantum computing is moving to the next stage, namely demonstrating quantum advantage in solving practical problems. Two typical problems of this kind are computational-aided material design and drug discovery, in which quantum chemistry plays a critical role in answering questions such as ∼Which one is the best?∼. Many recent efforts have been devoted to the development of advanced quantum algorithms for solving quantum chemistry problems on noisy intermediate-scale quantum (NISQ) devices,2,4–14 while implementing these algorithms for complex problems is limited by available qubit counts, coherence time and gate fidelity. Specifically, without error correction, quantum simulations of quantum chemistry are viable only if low-depth quantum algorithms are implemented to suppress the total error rate. Recent advances in error mitigation techniques enable us to model many-electron problems with a dozen qubits and tens of circuit depths on NISQ devices,9 while such circuit sizes and depths are still a long way from practical applications.

The difference between the available and actually required quantum resources in practical quantum simulations has renewed the interest in divide and conquer (DC) based methods.15–19 Realistic material and (bio)chemistry systems often involve complex environments, such as surfaces and interfaces. To model these systems, the Schrödinger equations are much too complicated to be solvable. It therefore becomes desirable that approximate practical methods of applying quantum mechanics be developed.20 One popular scheme is to divide the complex problem under consideration into as many parts as possible until these become simple enough for an adequate solution, namely the philosophy of DC.21 The DC method is particularly suitable for NISQ devices since the sub-problem for each part can in principle be solved with fewer computational resources.15–18,22–25 One successful application of DC is to estimate the ground-state potential energy surface of a ring containing 10 hydrogen atoms using the density matrix embedding theory (DMET) on a trapped-ion quantum computer, in which a 20-qubit problem is decomposed into ten 2-qubit problems.18

DC often treats all subsystems at the same computational level and estimates physical observables by summing up the corresponding quantities of subsystems, while in practical simulations of complex systems, the particle–particle interactions may exhibit completely different characteristics in and between subsystems. Long-range Coulomb interactions can be well approximated as quasiclassical electrostatic interactions since empirical methods, such as empirical force filed (EFF) approaches,26 are promising to describe these interactions. As the distance between particles decreases, the repulsive exchange interactions from electrons having the same spin become important so that quantum mean-field approaches, such as Hartree–Fock (HF), are necessary to characterize these electronic interactions.

Apr 11, 2023

Beyond DNA and RNA: The Expanding Toolbox of Synthetic Genetics

Posted by in categories: bioengineering, biotech/medical, chemistry, evolution, genetics, nanotechnology

The remarkable physicochemical properties of the natural nucleic acids, DNA and RNA, define modern biology at the molecular level and are widely believed to have been central to life’s origins. However, their ability to form repositories of information as well as functional structures such as ligands (aptamers) and catalysts (ribozymes/DNAzymes) is not unique. A range of nonnatural alternatives, collectively termed xeno nucleic acids (XNAs), are also capable of supporting genetic information storage and propagation as well as evolution. This gives rise to a new field of “synthetic genetics,” which seeks to expand the nucleic acid chemical toolbox for applications in both biotechnology and molecular medicine. In this review, we outline XNA polymerase and reverse transcriptase engineering as a key enabling technology and summarize the application of “synthetic genetics” to the development of aptamers, enzymes, and nanostructures.

Copyright © 2019 Cold Spring Harbor Laboratory Press; all rights reserved.

Apr 11, 2023

The origin of life: RNA and protein co-evolution on the ancient Earth

Posted by in categories: biotech/medical, chemistry, evolution, genetics

How life emerged from simple non-life chemicals on the ancient Earth is one of the greatest mysteries in biology. The gene expression system of extant life is based on the interdependence between multiple molecular species (DNA, RNA, and proteins). While DNA is mainly used as genetic material and proteins as functional molecules in modern biology, RNA serves as both genetic material and enzymes (ribozymes). Thus, the evolution of life may have begun with the birth of a ribozyme that replicated itself (the RNA world hypothesis), and proteins and DNA joined later. However, the complete self-replication of ribozymes from monomeric substrates has not yet been demonstrated experimentally, due to their limited activity and stability. In contrast, peptides are more chemically stable and are considered to have existed on the ancient Earth, leading to the hypothesis of RNA-peptide co-evolution from the very beginning. Our group and collaborators recently demonstrated that peptides with both hydrophobic and cationic moieties (e.g., KKVVVVVV) form β-amyloid aggregates that adsorb RNA and enhance RNA synthesis by an artificial RNA polymerase ribozyme and a simple peptide with only seven amino acid types (especially rich in valine and lysine) can fold into the ancient β-barrel conserved in various enzymes, including the core of cellular RNA polymerases. These findings, together with recent reports from other groups, suggest that simple prebiotic peptides could have supported the ancient RNA-based replication system, gradually folded into RNA-binding proteins, and eventually evolved into complex proteins like RNA polymerase.

Keywords: RNA world; ancient proteins; central dogma; origin of life; peptide.

© 2023 Japanese Society of Developmental Biologists.

Apr 11, 2023

A split ribozyme that links detection of a native RNA to orthogonal protein outputs

Posted by in categories: bioengineering, biotech/medical, chemistry

Individual RNA remains a challenging signal to synthetically transduce into different types of cellular information. Here, we describe Ribozyme-ENabled Detection of RNA (RENDR), a plug-and-play strategy that uses cellular transcripts to template the assembly of split ribozymes, triggering splicing reactions that generate orthogonal protein outputs. To identify split ribozymes that require templating for splicing, we use laboratory evolution to evaluate the activities of different split variants of the Tetrahymena thermophila ribozyme. The best design delivers a 93-fold dynamic range of splicing with RENDR controlling fluorescent protein production in response to an RNA input. We further resolve a thermodynamic model to guide RENDR design, show how input signals can be transduced into diverse outputs, demonstrate portability across different bacteria, and use RENDR to detect antibiotic-resistant bacteria. This work shows how transcriptional signals can be monitored in situ and converted into different types of biochemical information using RNA synthetic biology.

© 2023. The Author(s).

Conflict of interest statement.

Apr 11, 2023

Ribozyme-mediated RNA synthesis and replication in a model Hadean microenvironment

Posted by in categories: biological, chemistry, genetics, robotics/AI

Enzyme-catalyzed replication of nucleic acid sequences is a prerequisite for the survival and evolution of biological entities. Before the advent of protein synthesis, genetic information was most likely stored in and replicated by RNA. However, experimental systems for sustained RNA-dependent RNA-replication are difficult to realise, in part due to the high thermodynamic stability of duplex products and the low chemical stability of catalytic RNAs. Using a derivative of a group I intron as a model for an RNA replicase, we show that heated air-water interfaces that are exposed to a plausible CO2-rich atmosphere enable sense and antisense RNA replication as well as template-dependent synthesis and catalysis of a functional ribozyme in a one-pot reaction. Both reactions are driven by autonomous oscillations in salt concentrations and pH, resulting from precipitation of acidified dew droplets, which transiently destabilise RNA duplexes. Our results suggest that an abundant Hadean microenvironment may have promoted both replication and synthesis of functional RNAs.

© 2023. The Author(s).

Conflict of interest statement.

Apr 11, 2023

Catalytic Synthesis of Polyribonucleic Acid on Prebiotic Rock Glasses

Posted by in category: chemistry

Reported here are experiments that show that ribonucleoside triphosphates are converted to polyribonucleic acid when incubated with rock glasses similar to those likely present 4.3−4.4 billion years ago on the Hadean Earth surface, where they were formed by impacts and volcanism. This polyribonucleic acid averages 100–300 nucleotides in length, with a substantial fraction of 3’,-5’-dinucleotide linkages. Chemical analyses, including classical methods that were used to prove the structure of natural RNA, establish a polyribonucleic acid structure for these products. The polyribonucleic acid accumulated and was stable for months, with a synthesis rate of 2 × 10-3 pmoles of triphosphate polymerized each hour per gram of glass (25°C, pH 7.5). These results suggest that polyribonucleotides were available to Hadean environments if triphosphates were. As many proposals are emerging describing how triphosphates might have been made on the Hadean Earth, the process observed here offers an important missing step in models for the prebiotic synthesis of RNA.

Keywords: Impact glasses; Mafic rocks; Nucleoside triphosphates; Origin of life; Prebiotic chemistry; RNA world.

Conflict of interest statement.

Apr 10, 2023

Researchers print fully recyclable electronics that replace toxic chemicals with water

Posted by in categories: chemistry, electronics

The team developed a cyclical process in which the device is rinsed with water, dried in relatively low heat, and printed on again.

In the electronics industry, placing several layers of components on top of each other to develop complex devices is no easy task. And with printed electronics, the task is more complicated.

“If you’re making a peanut butter and jelly sandwich, one layer on either slice of bread is easy,” Aaron Franklin, the Addy Professor of Electrical and Computer Engineering at Duke, said in a statement. “But if you put the jelly down first and then try to spread peanut butter on top of it, forget it, the jelly won’t stay put and will intermix with the peanut butter.

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Apr 10, 2023

Researchers devise new membrane mirrors for large space-based telescopes

Posted by in categories: chemistry, physics, space

Researchers have developed a new way to produce and shape large, high-quality mirrors that are much thinner than the primary mirrors previously used for telescopes deployed in space. The resulting mirrors are flexible enough to be rolled up and stored compactly inside a launch vehicle.

“Launching and deploying space telescopes is a complicated and costly procedure,” said Sebastian Rabien from Max Planck Institute for Extraterrestrial Physics in Germany. “This new approach—which is very different from typical mirror production and polishing procedures—could help solve weight and packaging issues for telescope mirrors, enabling much larger, and thus more sensitive, telescopes to be placed in orbit.”

In the journal Applied Optics, Rabien reports successful fabrication of parabolic membrane mirror prototypes up to 30 cm in diameter. These mirrors, which could be scaled up to the sizes needed in space telescopes, were created by using chemical vapor deposition to grow membrane mirrors on a rotating liquid inside a vacuum chamber. He also developed a method that uses heat to adaptively correct imperfections that might occur after the mirror is unfolded.

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