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Space and laboratory discovery of HC₃ S.

ABSTRACT: We report the detection in TMC-1 of the protonated form of C₃S. The discovery of the cation HC₃S⁺ was carried through the observation of four harmonically related lines in the Q band using the Yebes 40m radiotelescope, and is supported by accurate ab initio calculations and laboratory measurements of its rotational spectrum. We derive a column density N(HC₃S⁺) = (2.0 ± 0.5) × 10¹¹ cm^-2, which translates to an abundance ratio C₃S/HC₃S⁺ of 65 ± 20. This ratio is comparable to the CS/HCS⁺ ratio (35 ± 8) and is a factor of about ten larger than the C₃O/HC₃O⁺ ratio previously found in the same source. However, the abundance ratio HC₃O⁺/HC₃S⁺ is 1.0 ± 0.5, while C₃O/C₃S is just ~ 0.11. We also searched for protonated C₂S in TMC-1, based on ab initio calculations of its spectroscopic parameters, and derive a 3σ upper limit of N(HC₂S⁺)≤ 9×10¹¹ cm^-2 and a C₂S/HC₂S⁺ ≥ 60. The observational results are compared with a state-of-the-art gas-phase chemical model and conclude that HC₃S⁺ is mostly formed through several pathways: proton transfer to C₃S, reaction of S⁺ with c-C₃H₂, and reaction between neutral atomic sulfur and the ion C₃H⁺ ₃.

SUBMITTER: Cernicharo J

PROVIDER: S-EPMC7610522 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:"Nanomedicine" is the application of purposely designed nano-scale materials for improved therapeutic and diagnostic outcomes, which cannot be otherwise achieved using conventional delivery approaches. While "translation" in drug development commonly encompasses the steps from discovery to human clinical trials, a different set of translational steps is required in nanomedicine. Although significant development effort has been focused on nanomedicine, the translation from laboratory formulations up to large scale production has been one of the major challenges to the success of such nano-therapeutics. In particular, scale-up significantly alters momentum and mass transfer rates, which leads to different regimes for the formation of nanomedicines. Therefore, unlike the conventional definition of translational medicine, a key component of "bench-to-bedside" translational research in nanomedicine is the scale-up of the synthesis and processing of the nano-formulation to achieve precise control of the nanoscale properties. This consistency requires reproducibility of size, polydispersity and drug efficacy. METHODS:Here we demonstrate that Flash NanoPrecipitation (FNP) offers a scalable and continuous technique to scale up the production rate of nanoparticles from a laboratory scale to a pilot scale. FNP is a continuous, stabilizer-directed rapid precipitation process. Lumefantrine, an anti-malaria drug, was chosen as a representative drug that was processed into 200 nm nanoparticles with enhanced bioavailability and dissolution kinetics. Three scales of mixers, including a small-scale confined impinging jet mixer, a mid-scale multi-inlet vortex mixer (MIVM) and a large-scale multi-inlet vortex mixer, were utilized in the formulation. The production rate of nanoparticles was varied from a few milligrams in a laboratory batch mode to around 1 kg/day in a continuous large-scale mode, with the size and polydispersity similar at all scales. RESULTS:Nanoparticles of 200 nm were made at all three scales of mixers by operating at equivalent Reynolds numbers (dynamic similarity) in each mixer. Powder X-ray diffraction and differential scanning calorimetry demonstrated that the drugs were encapsulated in an amorphous form across all production rates. Next, scalable and continuous spray drying was applied to obtain dried powders for long-term storage stability. For dissolution kinetics, spray dried samples produced by the large-scale MIVM showed 100% release in less than 2 h in both fasted and fed state intestinal fluids, similar to small-batch low-temperature lyophilization. CONCLUSIONS:These results validate the successful translation of a nanoparticle formulation from the discovery scale to the clinical scale. Coupling nanoparticle production using FNP processing with spray drying offers a continuous nanofabrication platform to scale up nanoparticle synthesis and processing into solid dosage forms.

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Space and laboratory discovery of HC3 S.

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Space and laboratory discovery of HC₃ S.