The Seventeenth Data Release of the Sloan Digital Sky Surveys: Complete Release of MaNGA, MaStar and APOGEE-2 Data

This paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which reached its goal of surveying over 10,000 nearby galaxies. The complete release of the MaNGA Stellar Library (MaStar) accompanies this data, providing observations of almost 30,000 stars through the MaNGA instrument during bright time. DR17 also contains the complete release of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) survey which publicly releases infra-red spectra of over 650,000 stars. The main sample from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), as well as the sub-survey Time Domain Spectroscopic Survey (TDSS) data were fully released in DR16. New single-fiber optical spectroscopy released in DR17 is from the SPectroscipic IDentification of ERosita Survey (SPIDERS) sub-survey and the eBOSS-RM program. Along with the primary data sets, DR17 includes 25 new or updated Value Added Catalogs (VACs). This paper concludes the release of SDSS-IV survey data. SDSS continues into its fifth phase with observations already underway for the Milky Way Mapper (MWM), Local Volume Mapper (LVM) and Black Hole Mapper (BHM) surveys

Yarrowia lipolytica Extracellular Lipase Lip2 as Biocatalyst for the Ring-Opening Polymerization of ε-Caprolactone

Yarrowia lipolytica (YL) is a “non-conventional” yeast that is capable of producing important metabolites. One of the most important products that is secreted by this microorganism is lipase, a ubiquitous enzyme that has considerable industrial potential and can be used as a biocatalyst in the pharmaceutical, food, and environmental industries. In this work, Yarrowia lipolytica lipase (YLL) was immobilized on Lewatit and Amberlite beads and is used in the enzymatic ring-opening polymerization (ROP) of cyclic esters in the presence of different organic solvents. YLL immobilized on Amberlite XAD7HP had the higher protein adsorption (96%) and a lipolytic activity of 35 U/g. Lewatit VPOC K2629 has the higher lipolytic activity (805 U/g) and 92% of protein adsorption. The highest molecular weight (Mn 10,685 Da) was achieved at 90 °C using YLL that was immobilized on Lewatit 1026 with decane as solvent after 60 h and 100% of monomer conversion

Chemo-Enzymatic Syntheses of Polyester-Urethanes

9 páginas.-- Editores: H. N. Cheng y Richard A. Gross.The enzymatic synthesis of α-ω-telechelic polycaprolactone diols (HOPCLOH) and triblock copolymers was studied. Synthesis of α-ω-telechelic PCL diols was achieved by enzymatic ring opening polymerization with Yarrowia lipolytica lipase immobilized on a macroporous resin Lewatit VP OC 1026, and using diethylene glycol and poly(ethylene glycol) as initiators. Biodegradable linear polyester-urethanes were prepared from synthesized PCL diols and hexamethylenediisocyanate (HDI). Depending on the length of PCL in HOPCLOH, the polymers were amorphous or semicrystalline. Measured mechanical properties strongly depend upon the degree of crystallinity of HOPCLOH.Peer reviewe

Enzymatic ring-opening polymerization of ε-caprolactone by Yarrowia lipolytica lipase in ionic liquids

12 páginas, 17 figuras, 1 esquema, 2 tablas.Yarrowia lipolytica (YLL), Candida rugosa (CRL), and porcine pancreatic lipase (PPL) were employed successfully as catalysts in the enzymatic ring-opening polymerization (ROP) of ε-caprolactone in the presence of 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1-butylpyridinium tetrafluoroborate ([BuPy][BF4]), 1-butylpyridinium trifluoroacetate ([BuPy][CF3COO]), 1-ethyl-3-methylimidazolium nitrate ([EMIM][NO3]) ionic liquids. Poly(ε-caprolactone)s (PCLs) with molecular weights (Mn) in the range of 300–9000 Da were obtained. 1H- and 13C-NMR analyses on PCLs formed by YLL, CRL, and PPL showed asymmetric telechelic -hydroxy-ω-carboxylic acid end groups. Differences between CP-MAS and MAS spectra are observed and discussed in terms of morphology. MALDI-TOF spectra show the formation of at least seven species. Differential scanning calorimetry (DSC) and Wide Angle X-Ray Scattering (WAXS) results demonstrate the high degree of crystallinity present in all the polyesters.Contract grant sponsor: Consejo Nacional de Ciencia y Tecnología (CONACyT); contract grant number: SEP-2004- C01-47173E. Contract grant sponsor: Consejo de Ciencia y Tecnología del Estado de Guanajuato (CONCYTEG). Contract grant sponsor: Universidad de Guanajuatato.Peer reviewe

Synthesis, characterization and hydrolytic degradation of polyester-urethanes obtained by lipase biocatalysis

The enzymatic synthesis of ¿¿¿-telechelic polycaprolactone diols (HOPCLOH) and block copolymers was studied. Synthesis of ¿¿¿-telechelic PCL diols was carried out by enzymatic ring opening polymerization with Yarrowia lipolytica lipase immobilized on Lewatit VP OC K2629 and Amberlyst 15, and using ethylene glycol, diethylene glycol and polyethylene glycol as initiators. Biodegradable linear polyester-urethanes were prepared from synthesized PCL diols and hexamethylenediisocyanate (HDI). Polyester-urethanes degradation was studied using thermogravimetric analysis (TGA) and hydrolysis (alkaline, acidic and neutral). It was found that content of ether linkages influences the thermal stability and hydrolytic degradation behavior of the analyzed polyurethanes. Hydrolytic degradation proceeds faster in alkaline media, in agreement with the expected susceptibility of ester COO¿ bonds to degradation in the polyester urethanes.Peer Reviewe

Bio-Catalysis for the Functionalization of Cellulose Nanocrystals

In this work, the chemical modification of cellulose nanocrystals (NCs) using an enzyme as a catalyst has been performed by a “grafting from” reaction, in order to covalently functionalize the external surface of NCs with both poly(L-lactic acid) (PLLA) and poly(ε-caprolactone) (PCL) by ring-opening polymerization. Firstly, cellulose nanocrystals were prepared from commercial cellulose microcrystals by acid hydrolysis and then functionalized by using Yarrowia lipolytica lipase immobilized on Lewatit resin as a catalyst. To confirm the success of the grafting reactions, H-NMR has been performed as well as FT-IR and Raman spectroscopy. Moreover, thermogravimetric analysis has been used to determine the amount of polymeric chains grafted onto the surface of cellulose nanocrystals. Furthermore, the crystalline nature of the polymeric chains grafted onto the cellulose surface has been studied by DSC, X-ray scattering, as well as SAXS analysis. To our knowledge, it is the first time that a biocatalyst approach has been used to obtain biopolymeric functionalized cellulose nanocrystals.This research was funded by the Ministerio de Ciencia e Innovación (PID2021-123753NB-C31; PID2020-119047RB-I00)

Semi-Continuous Heterophase Polymerization to Synthesize Poly(methacrylic acid)-Based Nanocomposites for Drug Delivery

The design of nanocomposites with the potential for drug delivery is a topic of great interest. In this work, the synthesis of nanocomposites of poly(methacrylic acid) (PMAA) grafted onto carbon nanotubes (CNTs) functionalized with poly(amidoamine) (PAMAM) dendrimer by semicontinuous heterophase polymerization SHP, at three different methacrylic acid (MAA) dosing rates, is reported. SHP is a polymerization technique poorly used to prepare nanocomposites containing CNTs and has the potential to produce more ordered alkyl methacrylic polymer chains, which could favor the obtaining of a homogenous nanocomposite. For the nanocomposites synthesized, a lowest addition rate monomer-starved condition was reached. Analysis by X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) demonstrate that functionalized CNTs are grafted onto the PMAA matrix. The ability of prepared nanocomposites to deliver hydrocortisone was evaluated by ultraviolet-visible spectroscopy (UV-Vis). The hydrocortisone release profiles of pure PMAA and of their nanocomposites prepared at the lowest monomer fed rate were fitted with Higuchi and Korsmeyer–Peppas models, successfully. Functionalized CNTs have a crucial role to induce an effective release of hydrocortisone from the prepared nanocomposites

Synthesis of Poly(methacrylic acid-co-butyl acrylate) Grafted onto Functionalized Carbon Nanotube Nanocomposites for Drug Delivery

Design of a smart drug delivery system is a topic of current interest. Under this perspective, polymer nanocomposites (PNs) of butyl acrylate (BA), methacrylic acid (MAA), and functionalized carbon nanotubes (CNTsf) were synthesized by in situ emulsion polymerization (IEP). Carbon nanotubes were synthesized by chemical vapor deposition (CVD) and purified with steam. Purified CNTs were analyzed by FE-SEM and HR-TEM. CNTsf contain acyl chloride groups attached to their surface. Purified and functionalized CNTs were studied by FT-IR and Raman spectroscopies. The synthesized nanocomposites were studied by XPS, 13C-NMR, and DSC. Anhydride groups link CNTsf to MAA–BA polymeric chains. The potentiality of the prepared nanocomposites, and of their pure polymer matrices to deliver hydrocortisone, was evaluated in vitro by UV–VIS spectroscopy. The relationship between the chemical structure of the synthesized nanocomposites, or their pure polymeric matrices, and their ability to release hydrocortisone was studied by FT-IR spectroscopy. The hydrocortisone release profile of some of the studied nanocomposites is driven by a change in the inter-associated to self-associated hydrogen bonds balance. The CNTsf used to prepare the studied nanocomposites act as hydrocortisone reservoirs