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13 March 2023

Design of Oscillatory Networks through Post-Translational Control of Network Components

Many essential functions in biological systems, including cell cycle progression and circadian rhythm regulation, are governed by the periodic behaviors of specific molecules. These periodic behaviors arise from the precise arrangement of components in biomolecular networks that generate oscillatory output signals. The dynamic properties of individual components of these networks, such as maturation delays and degradation rates, often play a key role in determining the network's oscillatory behavior. In this study, we explored the post-translational modulation of network components as a means to generate genetic circuits with oscillatory behaviors and perturb the oscillation features. Specifically, we used the NanoDeg platform—A bifunctional molecule consisting of a target-specific nanobody and a degron tag—to control the degradation rates of the circuit’s components and predicted the effect of NanoDeg-mediated post-translational depletion of a key circuit component on the behavior of a series of proto-oscillating network topologies. We modeled the behavior of two main classes of oscillators, namely relaxation oscillator topologies (the activator-repressor and the Goodwin oscillator) and ring oscillator topologies (repressilators). We identified two main mechanisms by which non-oscillating networks could be induced to oscillate through post-translational modulation of network components: an increase in the separation of timescales of network components and mitigation of the leaky expression of network components. These results are in agreement with previous findings describing the effect of timescale separation and mitigation of leaky expression on oscillatory behaviors. This work thus validates the use of tools to control protein degradation rates as a strategy to modulate existing oscillatory signals and construct oscillatory networks. In addition, this study provides the design rules to implement such an approach based on the control of protein degradation rates using the NanoDeg platform, which does not require genetic manipulation of the network components and can be adapted to virtually any cellular protein. This work also establishes a framework to explore the use of tools for post-translational perturbations of biomolecular networks and generates desired behaviors of the network output.

Keywords: Genetic oscillators; Protein degradation; Post-translational regulation; Nanobody; Synthetic genetic networks


13 March 2023

Review on Multi-Functional Separator for Li-S Batteries

Because lithium-ion batteries cannot meet increasing demand for power density, lithium metal batteries are expected as the next generation of rechargeable batteries. As one of lithium metal batteries, lithium-sulfur (Li-S) batteries have attracted extensive attention because of their ultrahigh power density (2600 Wh kg−1) and low cost of sulfur. In order to overcome problems of active material loss, volume expansion and dendritic growth of Li metal in Li-S batteries, researchers have adopted several methods such as adding electrolyte additives, electrode modification and separator modification. Among them, separator modification shows significant advantages in inhibiting the shuttle effect of lithium polysulfides. This paper reviews research progress of inhibiting the shuttle effect of Li-S batteries by the means of the separator modification in recent years, including direct design of new type of separator and physical/chemical modification of separator surface. Through extensive reading and summarizing of the research results of the separator modification of Li-S batteries, we give the possible development direction of Li-S batteries at the end of the paper.

Keywords: Li-S batteries; Functional separator; Shuttle effect


07 March 2023

Pulsed Ultraviolet C as a Potential Treatment for COVID-19

Currently, low dose radiotherapy (LDRT) is being tested for treating life-threatening pneumonia in COVID-19 patients. Despite the debates over the clinical use of LDRT, some clinical trials have been completed, and most are still ongoing. Ultraviolet C (UVC) irradiation has been proven to be highly efficient in inactivating the coronaviruses, yet is considerably safer than LDRT. This makes UVC an excellent candidate for treating COVID-19 infection, especially in case of severe pneumonia as well as the post COVID-19 pulmonary fibrosis. However, the major challenge in using UVC is its delivery to the lungs, the target organ of COVID-19, due to its low penetrability through biological tissues. We propose to overcome this challenge (i) by using pulsed UVC technologies which dramatically increase the penetrability of UVC through matter, and (ii) by integrating the pulsed UVC technologies into a laser bronchoscope, thus allowing UVC irradiation to reach deeper into the lungs. Although the exact characteristics of such a treatment should yet to be experimentally defined, this approach might be much safer and not less efficient than LDRT.

Keywords: UVC; Coronavirus 2 (SARS‑CoV‑2); COVID-19; Fibrosis; Optic fibers; Laser bronchoscope


03 March 2023

Spatial Characteristics and Influencing Factors of Migration in Kanagawa, Japan

In the context of “Tokyo centralization”, population migration has become an important factor affecting Kanagawa's economic growth, living standards, and employment status. On the other hand, with the development of the declining birth rate and aging society, migration for any purpose has an impact on social development. The government has released many policies to attract people from other cities to Kanagawa. This study analyzes the factors influencing the spatial pattern of population migration in Kanagawa based on the current spatial characteristics of population migration in Kanagawa from 2016~2020 and previous population migra-tion research theories. the influencing factors are analyzed empirically by selecting a total of 9 economic, social, and environmental indicators that may affect the spatial pattern of population migration in Kanagawa. The result showed that, when only the economic factor was considered, gross prefectural product, job opportunities, and consumer price index significantly influenced migration; When only environmental factors are considered, the number of pollution complaints successfully handled had a significant positive effect on population migration; When only the social environment is considered, the level of education becomes the main consid-eration for people. Furthermore, when the economic factors, environmental factors, and social factors are analyzed together, the gross prefectural domestic product, job opportunities, consumer price index, and the number of pollution complaints successfully handled all have an impact on migration in Kanagawa and the gross prefectural product is the common influencing factor.

Keywords: Kanagawa; Population migration; Spatial characteristics; Influencing factors


03 March 2023

SnS2 Quantum Dots Decorated MoS2 Nanosheets Enabling Efficient Photocatalytic H2 Evolution in CO2 Saturated Water

SnS2/MoS2 heterojunction nanocomposite was prepared by a one-step hydrothermal synthesis method. The nanocomposite exhibited much improved photocatalytic hydrogen evolution performance in CO2 saturated solution compared with pure MoS2 and SnS2 samples. The improved photocatalytic activity was attributed to the S-scheme heterojunction structure between SnS2 quantum dots and MoS2 nanosheets which facilitate electron-hole separation both in MoS2 and SnS2. In the S-scheme structure, the strong reduction ability of SnS2 quantum dots was well maintained for the improved H2 evolution. In situ DRIFT studies allowed us to suggest reaction pathways from CO2 and H2O to photocatalytic H2, CO, and CH4 generation.

Keywords: Photocatalysis; H2 evolution; CO2 hydrogenation; S-scheme


03 March 2023

Evaluating Different UAS Flight Methods for 3D Model Generation and Printing of a Tornado Destroyed Cultural Heritage: Caddo House in Texas

In recent years, the use of Unmanned Aerial Systems (UAS) to obtain imagery for photogrammetry has become commonplace. Using these data to develop 3D products has also grown significantly in both research and commercial applications. This study aims to find a relatively simple and low cost UAS flight method as a means to obtain data to produce a 3D model suitable for 3D printing. The study subject chosen to assess different flight methods was the Caddo House at Caddo Mounds State Historical Site located near Alto, Cherokee County, Texas, USA. To collect images for analysis, a DJI Phantom 4 Pro UAS was used with Pix4DCapture mission control app. Two main missions were carried out, one being a pre-defined double-grid flight, and the other being an orbital free-flight method. The findings of this study indicate that if the goal is to create a true-to-life 3D model of an object using UAS, the best method would be a curated orbital free-flight method. If there is time constraint and the subject is sufficiently large and not considerably irregular, a double-grid mission with sufficient forward and side overlap can produce desirable results, but with a slight loss of fine details. The 3D model developed from the curated orbital flight method was successfully printed with a customer grade FDM 3D printer.

Keywords: UAS; Orthomosaic; Cultural Heritage; 3D Model; 3D Printing


16 February 2023

Increasing Nutritional Value of Cyanobacteria by Engineering Valine, Phenylalanine, and Fatty Acid Production

In 2020, the United Nations estimated that 2.37 billion people globally were without food or unable to eat a healthy balanced diet. The number of people with insufficient nutrition has increased in the short term due to COVID-19 pandemic and longer-term climate change is leading to shifts in arable land and water availability leading to a continued need to develop scalable sources of nutrition. One of the options that can yield high food mass per square foot of land use is the high-density culture of microalgae or other photosynthetic microorganisms. While photosynthetic microorganisms may provide high amounts of biomass with a small land footprint, the nutritional value of unmodified microorganisms may be limited. This mini-review presents the base nutritional value in terms of macro- and micronutrients of several cyanobacteria (Nostoc, Anabaena, Spirulina) in relation to established human nutritional requirements as a starting point for better utilization of cyanobacteria as nutritional supplements. It also discusses synthetic biology approaches that have been implemented in different organisms to increase the production of L-valine, L-phenylalanine, and fatty acids demonstrating some common genetic engineering design approaches and some approaches that are organism-specific.

Keywords: Nutrition; L-valine; L-phenylalanine; Fatty acid; Photosynthetic microbe


07 February 2023

Production of Highly Modified C30-carotenoids with Singlet Oxygen-quenching Activities, 5-glucosyl-5,6-dihydro-4,4’-diapolycopen-4’-oic Acid, and Its Three Intermediates Using Genes from Planococcus maritimus Strain iso-3

Planococcus maritimus strain iso-3 was previously isolated from intertidal sediment in the North Sea and was found to produce a highly modified C30-carotenoid, methyl-5-glucosyl-5,6-dihydro-4,4’-diapolycopenoate, as the final product. In this study, we analyzed the function of the carotenoid terminal oxidase crtP (renamed cruO) and aldehyde dehydrogenase aldH genes in P. maritimus strain iso-3 and elucidated the carotenoid biosynthetic pathway for this strain at the gene level. We produced four novel C30-carotenoids with potent singlet oxygen-quenching activities, 5-glucosyl-5,6-dihydro-4,4’-diapolycopen-4’-oic acid and its three intermediates, which were obtained using E. coli cells carrying the cruO (and aldH) gene(s) in addition to the known P. maritimus carotenogenic genes.

Keywords: C30-carotenoids; Marine bacterium; Planococcus; Diapolycopenoic acid; Singlet oxygen-quenching activity


07 February 2023

Plasmon Enhanced Nickel(II) Catalyst for Photocatalytic Lignin Model Cleavage

Photocatalytic-induced cleaving of the ether C–O bond in model lignin compounds was studied with a closely-coupled compo-site material consisting of Ni(OH)2 and gold nanoparticles (NPs) on a zirconia support (Au/ZrO2–Ni(OH)2). The three important ether bond types consisting of α-O-4, β-O-4, and 4-O-5 linkages can all be cleaved using this catalyst at reaction temperatures 40, 85 and 95 °C when under low-flux visible light irradiation. The Au NPs action as a light-harvesting antenna provided light-generated hot electrons that reduced Ni2+ to Ni0. The Ni0 was the active catalytic site where reductive cleavage of ether C–O bonds occurred while it was oxidized to Ni2+ to complete the catalysis cycle. The plasmonic antenna system with supported Ni(OH)2 exhibited better ability for the catalytic reductive ether cleavages under visible light irradiation compared to photocata-lysts of Au NPs and Ni2+ ions immobilized on alumina fibers.

Keywords: Lignin model cleavage; Photocatalysis; LSPR effect; Mild conditions


30 January 2023

Metal-Free Lewis Pair Catalysts for a One-Pot Terpolymerization of Propylene Oxide, ʟ-Lactide and CO2

Multiblock and di-/tri-block copolymers are successfully synthesized for the first time via the metal-free terpolymerization of propylene oxide (PO), ʟ-lactide (LA) and CO2 in one-pot/one-step and one-pot/two-step protocols respectively. Firstly, triethyl borane (TEB) and bis(triphenylphosphine)iminium chloride (PPNCl) Lewis pair is employed in the ring-opening polymerization of LA, wherein the catalytic efficiency is significantly correlated to the TEB/PPNCl feed ratio. Next, a series of TEB/base pairs are selected to synthesize the PO/LA/CO2 terpolymer (PPCLA) in one-pot/one-step strategy. In PPCLA synthesis, LA exhibits the fastest reaction rate but severe transesterification is almost unavoidable, resulting in low molecular weight products. In order to prepare high-molecular-weight terpolymers, a one-pot/two-step methodology has to be applied. By this method, the copolymerization of PO/CO2 proceeds first to form poly(propylene carbonate) (PPC) macroinitiators, which triggers the polymerization of LA to polylactide (PLA), leading to PLA-PPC or PLA-PPC-PLA block copolymers. The synthesized PLA-PPC-PLA block copolymers display improved thermal stability compared with PPC.

Keywords: Metal-free catalysis; CO2 utilization; Biodegradable; Multiblock copolymer; Polylactide; Polycarbonate