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Annual Review of Vision Science Jul 2024Carotenoids, yellow and red pigments found abundantly in nature, play essential roles in various aspects of human physiology. They serve as critical molecules in vision... (Review)
Review
Carotenoids, yellow and red pigments found abundantly in nature, play essential roles in various aspects of human physiology. They serve as critical molecules in vision by functioning as antioxidants and as filters for blue light within the retina. Furthermore, carotenoids are the natural precursors of vitamin A, which is indispensable for the synthesis of retinaldehyde, the visual chromophore, and retinoic acid, a small molecule that regulates gene expression. Insufficient levels of carotenoids and retinoids have been linked to age-related macular degeneration and xerophthalmia, respectively. Nevertheless, the mechanisms by which the eye maintains carotenoid and retinoid homeostasis have remained a mystery. Recent breakthroughs identified the molecular players involved in this process and provided valuable biochemical insights into their functioning. Mutations in the corresponding genes disrupt the homeostasis of carotenoids and retinoids, leading to visual system pathologies. This review aims to consolidate our current understanding of these pathways, including their regulatory principles.
PubMed: 38954771
DOI: 10.1146/annurev-vision-102122-101846 -
Journal of the American Chemical Society Jul 2024In light of recent conflicting reports regarding the hydroformylation catalytic activity derived from cationic Co(II) precatalysts of the form...
In light of recent conflicting reports regarding the hydroformylation catalytic activity derived from cationic Co(II) precatalysts of the form [Co(acac)(bis(phosphine))]BF, the synthetic procedures and characterization of [Co(acac)(dppBz)]BF, , are evaluated. Leveraging calibrated ESI-TOF MS methodologies, substantial quantities of Co(acac)(dppBz), , were observed within samples of . The source of the impurity, , is determined to derive from incomplete protonolysis of the Co(acac) precursor and ligand scrambling occurring during the synthesis of . Revised synthetic procedures using lower temperature conditions and longer reaction times afford analytically pure samples of based on ESI-TOF MS and NMR spectroscopic analysis. Complex is demonstrated to act as a hydroformylation precatalyst for the conversion of 1-hexene to 1-heptanal under relatively mild conditions at 51.7 bar and 140 °C. The presence of impurity is shown to dramatically decrease the catalytic performance derived from .
PubMed: 38954757
DOI: 10.1021/jacs.4c04239 -
PLOS Global Public Health 2024In Kenya, overdose remains a major public health concern with approximately 40% of persons who inject drugs (PWID) reporting personal overdoses. PWID living with HIV...
In Kenya, overdose remains a major public health concern with approximately 40% of persons who inject drugs (PWID) reporting personal overdoses. PWID living with HIV (PWID-LH) are particularly vulnerable to experiencing fatal and non-fatal overdoses because of the surrounding physical, social, economic, and political environments, which are not fully understood in Kenya. Through qualitative inquiry, this study characterizes Kenya's overdose risk environment. Participants were purposively recruited from a larger cohort study from September to December 2018 using the following inclusion criteria: HIV-positive, age ≥18 years, injected drugs in the last year, and completed cohort study visits. Semi-structured interviews explored experiences of personal and observed overdoses, including injection settings, sequence of events (e.g., pre-, during, and post-overdose), safety strategies, and treatment. Interviews were transcribed, translated (Swahili to English), reviewed, and analyzed thematically, applying a risk environment framework. Nearly all participants described personal and/or observed overdose experiences (96%) and heroin was the most frequently reported substance (79%). Overdose precursors included increased consumption, polysubstance use, recent incarceration, and rushed injections. There were also indications of female-specific precursors, including violence and accessing prefilled syringes within occupational settings. Overdose safety strategies included avoiding injecting alone, injecting drugs incrementally, assessing drug quality, and avoiding polysubstance use. Basic first-aid techniques and naloxone use were common treatment strategies; however, naloxone awareness was low (25%). Barriers to treatment included social network abandonment, police discrimination, medical stigma, fatalism/religiosity, medical and transportation costs, and limited access to treatment services. In Kenya, the overdose risk environment highlights the need for comprehensive overdose strategies that address the physical, social, economic, and political environments. Morbidity and mortality from overdose among PWID-LH could be reduced through overdose prevention initiatives that support harm reduction education, naloxone awareness, and access, destigmatization of PWID, and reforming punitive policies that criminalize PWID-LH.
PubMed: 38954694
DOI: 10.1371/journal.pgph.0003435 -
Soft Matter Jul 2024Aluminosilicate hydrogels are often considered to be precursors for the crystallisation of zeolites carried out under hydrothermal conditions. The preparation of...
Aluminosilicate hydrogels are often considered to be precursors for the crystallisation of zeolites carried out under hydrothermal conditions. The preparation of mechanically homogeneous aluminosilicate gels enables the study of these materials through bulk rheology and observation of the aging dynamics until the precipitation of crystalline zeolites. The first part of this study deals with the establishment of ternary state diagrams, in order to identify the range of chemical formulations that enable preparation of single-phase homogeneous gels. Then, by studying the viscoelastic moduli during the gelation reaction, and by yielding the gel under large deformation, we propose an empirical law considering the partial order of reaction on each chemical element, to predict the gelation time according to the chemical formulation. The scaling behavior of the elastic properties of this colloidal gel shows a transition from a strong link behavior to a weak link regime. Long term aging results in the shrinkage of the gel, accompanied by syneresis of interstitial liquid at the surface. Zeolites precipitate through crystallisation by a particle attachment mechanism, when thermodynamic equilibrium is reached. The stoichiometry of the precipitated zeolites is not only consistent with the concentration of the remaining species in the supernatant but, surprisingly, it is also very close to the partial order of the reaction of the chemical elements involved in the determination of the critical gel point. This indicates a strong correlation between the morphology of the soft amorphous gel network that is formed at an early age and those of the final solid precipitated crystals.
PubMed: 38954470
DOI: 10.1039/d4sm00181h -
Environmental Science and Pollution... Jul 2024A novel 3D nitrogen-doped porous carbon supported Fe-Cu bimetallic nanoparticles composite (Fe-Cu-N-PC) was prepared via direct pyrolysis by employing black liquor...
A novel 3D nitrogen-doped porous carbon supported Fe-Cu bimetallic nanoparticles composite derived from lignin: an efficient peroxymonosulfate activator for naphthalene degradation.
A novel 3D nitrogen-doped porous carbon supported Fe-Cu bimetallic nanoparticles composite (Fe-Cu-N-PC) was prepared via direct pyrolysis by employing black liquor lignin as a main precursor, and it was utilized as a novel catalyst for PMS activation in degrading naphthalene. Under the optimum experimental conditions, the naphthalene degradation rate was up to 93.2% within 60 min in the Fe-Cu-N-PC/PMS system. The porous carbon framework of Fe-Cu-N-PC could facilitate the quick molecule diffusion of reactants towards the inner bimetallic nanoparticles and enriched naphthalene molecules from the solution by a specific adsorption, which increased the odds of contact between naphthalene and reactive oxygen species and improved the reaction efficiency. The quenching reaction proved that the non-free radical pathway dominated by O was the main way in naphthalene degradation, while the free radical pathway involving SO and ·OH only played a secondary role. Moreover, owing to its high magnetization performance, Fe-Cu-N-PC could be magnetically recovered and maintained excellent naphthalene degradation rate after four degradation cycles. This research will offer a theoretical basis for the construction of facile, efficient, and green technologies to remediate persistent organic pollutants in the environment.
PubMed: 38954339
DOI: 10.1007/s11356-024-34147-3 -
Bulletin of Experimental Biology and... Jul 2024The features of the participation of Smad3 in the functioning of neural stem cells (NSC), neuronal committed precursors (NCP), and neuroglial elements were studied in...
The features of the participation of Smad3 in the functioning of neural stem cells (NSC), neuronal committed precursors (NCP), and neuroglial elements were studied in vitro. It was found that this intracellular signaling molecule enhances the clonogenic and proliferative activities of NCP and inhibits specialization of neuronal precursors. At the same time, Smad3 does not participate in the realization of the growth potential of NSC. With regard to the secretory function (production of neurotrophic growth factors) of neuroglial cells, the stimulating role of Smad3-mediated signaling was shown. These results indicate the promise of studying the possibility of using Smad3 as a fundamentally new target for neuroregenerative agents.
PubMed: 38954301
DOI: 10.1007/s10517-024-06126-8 -
Brazilian Journal of Microbiology :... Jul 2024Microorganisms are known to be a promising source of biopigments because they are easy to obtain, can be produced on a commercial scale, and are environmentally...
Microorganisms are known to be a promising source of biopigments because they are easy to obtain, can be produced on a commercial scale, and are environmentally friendly. Therefore, the aim of this work was to characterize a brown pigment (BP) produced by HM053 in NFbHPN-lactate medium. The BP was extracted from the pellet (BPP) or supernatant (BPS), in the presence (BPPTrp, BPSTrp) or absence (BPPw, BPSw) of tryptophan (Trp). The UV-vis results were similar among all BP samples and compared with commercial melanin used as a standard, and the maximum absorption was observed around 200-220 nm. FTIR spectra showed that BP and commercial melanin had slight differences, with a small band between 3000-2840 cm, related to C-H in the CH and CH aliphatic groups, which is not observed in the commercial melanin. Between BPP and BPS showed a different structure with bands in the region 1230-1070 cm related to groups C-O. The thermogravimetric curves for BPSw and BPSTrp showed similar behavior, with 4 stages of mass loss. The similarity between BPPw and BPPTrp with 2 stages of mass loss was also observed. Scanning electron microscopy results showed morphological differences between BPP and BPS, where BPP had a physical structure more homogeneous and a regular flat surface, while the BPS physical structure did not seem homogeneous and the surface was uneven with some spherical structures as commercial melanin.
PubMed: 38954221
DOI: 10.1007/s42770-024-01433-8 -
Nano-micro Letters Jul 2024The impedance matching of absorbers is a vital factor affecting their microwave absorption (MA) properties. In this work, we controllably synthesized Material of...
The impedance matching of absorbers is a vital factor affecting their microwave absorption (MA) properties. In this work, we controllably synthesized Material of Institute Lavoisier 88C (MIL-88C) with varying aspect ratios (AR) as a precursor by regulating oil bath conditions, followed by one-step thermal decomposition to obtain carbon-coated iron-based composites. Modifying the precursor MIL-88C (Fe) preparation conditions, such as the molar ratio between metal ions and organic ligands (M/O), oil bath temperature, and oil bath time, influenced the phases, graphitization degree, and AR of the derivatives, enabling low filler loading, achieving well-matched impedance, and ensuring outstanding MA properties. The MOF-derivatives 2 (MD)/polyvinylidene Difluoride (PVDF), MD/PVDF, and MD/PVDF absorbers all exhibited excellent MA properties with optimal filler loadings below 20 wt% and as low as 5 wt%. The MD/PVDF (5 wt%) achieved a maximum effective absorption bandwidth (EAB) of 5.52 GHz (1.90 mm). The MD/PVDF (10 wt%) possessed a minimum reflection loss (RL) value of - 67.4 at 12.56 GHz (2.13 mm). A symmetric gradient honeycomb structure (SGHS) was constructed utilizing the high-frequency structure simulator (HFSS) to further extend the EAB, achieving an EAB of 14.6 GHz and a RL of - 59.0 dB. This research offers a viable inspiration to creating structures or materials with high-efficiency MA properties.
PubMed: 38954048
DOI: 10.1007/s40820-024-01435-z -
The Journal of Physical Chemistry. A Jul 2024The ultraviolet (UV) photodissociation dynamics of the 1-methylallyl (1-MA) radical were studied using the high- Rydberg atom time-of-flight (HRTOF) technique in the...
The ultraviolet (UV) photodissociation dynamics of the 1-methylallyl (1-MA) radical were studied using the high- Rydberg atom time-of-flight (HRTOF) technique in the wavelength region of 226-244 nm. The 1-MA radicals were produced by 193 nm photodissociation of the 3-chloro-1-butene and 1-chloro-2-butene precursor. The 1 + 1 REMPI spectrum of 1-MA agrees with the previous UV absorption spectrum in this wavelength region. Quantum chemistry calculations show that the UV absorption is mainly attributed to the 3 Rydberg state (perpendicular to the allyl plane). The H atom photofragment yield (PFY) spectrum of 1-MA from 3-chloro-1-butene displays a broad peak around 230 nm, while that from 1-chloro-2-butene peaks at ∼236 nm. The translational energy distributions of the H atom loss product channel, ()'s, show a bimodal distribution indicating two dissociation pathways in 1-MA. The major pathway is isotropic in product angular distribution with β ∼ 0 and has a low fraction of average translational energy in the total excess energy, ⟨⟩, in the range of 0.13-0.17; this pathway corresponds to unimolecular dissociation of 1-MA after internal conversion to form 1,3-butadiene + H. The minor pathway is anisotropic with β ∼ -0.23 and has a large ⟨⟩ of ∼0.62-0.72. This fast pathway suggests a direct dissociation of the methyl H atom on a repulsive excited state surface or the repulsive part of the ground state surface to form 1,3-butadiene + H. The fast/slow pathway branching ratio is in the range of 0.03-0.08.
PubMed: 38953902
DOI: 10.1021/acs.jpca.4c02535 -
Inorganic Chemistry Jul 2024Exfoliation of graphite and the discovery of the unique properties of graphene─graphite's single layer─have raised significant attention to layered compounds as...
Exfoliation of graphite and the discovery of the unique properties of graphene─graphite's single layer─have raised significant attention to layered compounds as potential precursors to 2D materials with applications in optoelectronics, spintronics, sensors, and solar cells. In this work, a new orthorhombic polymorph of yttrium bromide, 16-YBr was synthesized from yttrium and CBr in a laser-heated diamond anvil cell at 45 GPa and 3000 K. The structure of 16-YBr was solved and refined using in situ synchrotron single-crystal X-ray diffraction. At high pressure, it can be described as a 3D framework of YBr polyhedra, but upon decompression below 15 GPa, the structure motif changes to layered, with layers comprising edge-sharing YBr polyhedra weakly bonded by van der Waals interactions. The layered 16-YBr material can be recovered to ambient conditions, and according to Perdew-Burke-Ernzerhof-density functional theory calculations, it exhibits semiconductor properties with a band gap that is highly sensitive to pressure. This polymorph possesses a low exfoliation energy of 0.30 J/m. Our results expand the list of layered trivalent rare-earth metal halides and provide insights into how high pressure alters their structural motifs and physical properties.
PubMed: 38953784
DOI: 10.1021/acs.inorgchem.4c00813