RESUMEN

Hematite (α-Fe2O3) emerges as an enticing material for visible-light-driven photocatalysis owing to its remarkable stability, low toxicity, and abundance. However, its inherent shortcomings, such as a short hole diffusion length and high recombination rate, hinder its practical application. Recently, oxygen vacancies (Vo) within hematite have been demonstrated to modulate its photocatalytic attributes. The effects of Vo can be broadly categorized into two opposing aspects: (1) acting as electron donors, enhancing carrier conductivity, and improving photocatalytic performance and (2) acting as surface carrier traps, accelerating excited carrier recombination, and deteriorating performance. Critically, the generation rate, distribution, role, and behavior of Vo significantly differ for synthesis methods due to differences in formation mechanisms and oxygen diffusion. This complexity hampers simplified discussions of Vo, necessitating careful investigation and nuanced discussion tailored to the specific method and conditions employed. Among various approaches, hydrothermal synthesis offers a simple and cost-effective route. Here, we demonstrate a hydrothermal synthesis method for Vo introduction to hematite using a carbon source, where variations in the heating rate have not been previously explored in terms of their influence on Vo generation. The analyses revealed that the concentration of Vo was maximized at a heating rate of 16 °C/min, indicative of a high density of surface defects. With regard to photocatalytic performance, elevated heating rates (16 °C/min) fostered the formation of Vo primarily on the hematite surface. The photocatalytic activity was 7.1 times greater than that of the sample prepared at a low heating rate (2 °C/min). These findings highlight the crucial role of surface defects, as opposed to bulk defects, in promoting hematite photocatalysis. Furthermore, the facile control over Vo concentration achievable via manipulating the heating rate underscores the promising potential of this approach for optimizing hematite photocatalysts.

RESUMEN

Mallotus japonicus is a valuable traditional medicinal plant in East Asia for applications as a gastrointestinal drug. However, the molecular components involved in the biosynthesis of bioactive metabolites have not yet been explored, primarily due to a lack of omics resources. In this study, we established metabolome and transcriptome resources for M. japonicus to capture the diverse metabolite constituents and active transcripts involved in its biosynthesis and regulation. A combination of untargeted metabolite profiling with data-dependent metabolite fragmentation and metabolite annotation through manual curation and feature-based molecular networking established an overall metabospace of M. japonicus represented by 2129 metabolite features. M. japonicus de novo transcriptome assembly showed 96.9% transcriptome completeness, representing 226,250 active transcripts across seven tissues. We identified specialized metabolites biosynthesis in a tissue-specific manner, with a strong correlation between transcripts expression and metabolite accumulations in M. japonicus. The correlation- and network-based integration of metabolome and transcriptome datasets identified candidate genes involved in the biosynthesis of key specialized metabolites of M. japonicus. We further used phylogenetic analysis to identify 13 C-glycosyltransferases and 11 methyltransferases coding candidate genes involved in the biosynthesis of medicinally important bergenin. This study provides comprehensive, high-quality multi-omics resources to further investigate biological properties of specialized metabolites biosynthesis in M. japonicus.

Asunto(s)

RESUMEN

Changes in preference are inherently subjective and internal psychological events. We have identified brain events that presage ultimate (rather than intervening) choices, and signal the finality of a choice. At the first exposure to a pair of faces, caudate activity reflected the face of final choice, even if an initial choice was different. Furthermore, the orbitofrontal cortex and hippocampus exhibited correlations only when the subject had made a choice that would not change.

Asunto(s)

RESUMEN

To survive under changing circumstances, we have to make appropriate decisions on our behavior. For this purpose, the brain should recognize reward information from objects under a given circumstances. Recent experimental and theoretical studies have suggested that primates, including human beings, have at least 2 brain processes that calculate the reward value of objects. One is the process coding a specific reward value of a stimulus or response, depending on direct experience (e.g., classical conditioning and TD learning). The other enables us to predict reward based on the internal model of given circumstances without direct experience (e.g., categorization and inference). To clarify the neuronal correlates of the multiple processes on reward prediction, we have conducted 4 experiments: (1) single-unit recording from the caudate and lateral prefrontal cortex of a monkey, while it performed a memory-guided saccade task with asymmetric reward schedule; (2) human fMRI imaging during random-dot discrimination with asymmetric reward condition; (3) single-unit recording from the monkey dopamine neuron in the random-dot discrimination task with asymmetric reward schedule; and (4) simultaneous single-unit recording from the striatum and lateral prefrontal cortex of monkeys performing a reward inference task. Results suggest that the nigro striatal network and the prefrontal network have different functional roles for reward prediction (value generation). The former applies the model-free method (temporal-difference learning), while the latter uses the model-based method (category-based learning).

Asunto(s)

RESUMEN

AIM: The aim of the present study was to investigate the effects of acute paroxetine administration on brain activity related to motivation. METHODS: Sixteen healthy subjects participated in a randomized, single-blind, no-drug/placebo-controlled, cross-over study. After administration of no drug, placebo or paroxetine (selective serotonin reuptake inhibitor; 20 mg), subjects underwent functional magnetic resonance imaging while performing a monetary incentive delay task. We analyzed the differences in brain activities of the reward anticipation/motor preparation period that are subject to motivational modulation. For this purpose, we subdivided the incentive trials on the basis of whether the reaction times (RT) were slower or faster than the subject's mean RT (slow RT and fast RT trials). RESULTS: No drug and placebo showed robust activation differences in the globus pallidus and putamen for the fast RT trials compared to the slow RT trials, whereas paroxetine showed none. Paroxetine showed significantly lower activations in the globus pallidus, insula, putamen and dorsolateral prefrontal cortex compared to no drug in the fast RT trials. CONCLUSIONS: Paroxetine single acute administration diminished brain activity induced by motivation in healthy subjects. This may partially explain the increased lack of motivation seen in patients with relatively mild symptoms after taking a dose of paroxetine for the first time.

Asunto(s)

RESUMEN

Ulva compressa L. is a heterothallic macroalga considered to be in the early evolutionary stage between isogamy and anisogamy. Two genetic lines of this species, each consisting of gametophytes with opposite mating types, were collected on the coasts of Ehime and Iwate prefectures: MGEC-1 (mt(+) ) and MGEC-2 (mt(-) ) from Ehime, and MGEC-5 (mt(+) ) and MGEC-6 (mt(-) ) from Iwate. Their relative gamete sizes (i.e., cell volumes) do not correspond to their mating types: MGEC-6 (19.8 µm(3) ) > MGEC-1 (18.6 µm(3) ) > MGEC-5 (17.0 µm(3) ) > MGEC-2 (10.1 µm(3) ). The pattern of organelle inheritance is an important sexual characteristic in many eukaryotes. We therefore investigated the relationship between gamete size and the inheritance of chloroplast DNA (cpDNA). Polymorphisms between the cpDNA of the two lines were used as markers. We found a 24 bp insertion between psbF and psbL, and the substitution of a StyI site (from CCAAGG to TCAAGG) in the intergenic region between petD and accD. Two interline crosses (MGEC-1 × MGEC-6 and MGEC-2 × MGEC-5) produced 42 and 38 zygotes, respectively. PCR and PCR-RFLP analyses showed that the cpDNA of the mt(+) gametes was consistently inherited in both crosses. The cpDNA is inherited from one parent only, and it depends not on gamete size but on being mt(+) . The cpDNA was observed during crossing and in the zygotes 6 h after mating. In 6% of the zygotes, the cpDNA derived from the mt(-) gametes disappeared 3-4 h after mating. Preferential digestion of the cpDNA in the zygote's mt(-) gamete may form the basis for uniparental inheritance of cpDNA.

RESUMEN

TiO(2) has been widely used in pharmaceutical products, and it also has been used as a photocatalyst. In this study, the influence of photocatalytic activity on the stability of solid-state mequitazine, an H(1)-blocker, was investigated. The photo-degradation of mequitazine with TiO(2) occurred under irradiation with both light sources. The degree of degradation of mequitazine with anatase was higher than that of rutile. The degradation was significantly enhanced with increasing relative humidity. The relationship between the apparent degradation rate constant and water vapor pressure could be clearly described by a simple power law. The major photo-degradation products of mequitazine, resulting from photocatalytic activity of TiO(2), were mequitazine-S-oxide and mequitazine-sulphone. A remarkable degradation of mequitadine occurred with addition of TiO(2), and its photocatalytic activity was controlled by water vapor pressure. The photo-degradation of mequitazine with TiO(2) is a different process from mequitazine without TiO(2), because mequitazine-S-oxide and mequitazine-sulphone are not formed with normal photo-degradation of mequitazine.

Asunto(s)

RESUMEN

To characterize the photocatalytic activity of TiO2 via solid-state reaction, the relationship between the physicochemical properties and photocatalytic activity of TiO2 was investigated and estimated from the results of photodegradation of nisoldipine. The photodegradation of nisoldipine was significantly enhanced by addition of TiO2. Two degradation products, nitroso-phenylpyridine derivative and nitro-phenylpyridine derivative, were formed. The degree of photocatalytic activity of TiO2 was quite different between the various types of TiO2 investigated, even when the crystalline phase was the same. As a result of the investigations into the relationship between the photocatalytic activity and physicochemical properties of TiO2, it was found that for the rutile form the photocatalytic activity has good correlation with specific surface area of TiO2, but poor correlation with water loss on drying of TiO2. However, for the anatase form, the photocatalytic activity has good correlation with water loss on drying of TiO2, but poor correlation with specific surface area. Moreover, it was found that the crystallinity of TiO2 has a moderate correlation with the photocatalytic activity of both crystal forms of TiO2. These results suggest that a degree of photocatalytic activity of TiO2 depends on the various physicochemical properties of each type of TiO2 investigated.

Asunto(s)

RESUMEN

Human glia maturation factor-gamma (hGMFG) was recently identified as a gene that is homologous to glia maturation factor-beta (GMFB). In this study, we determined the organization of the 9.5-kb hGMFG gene and characterized its promoter activity. The 5'-flanking region of the first exon has putative elements for binding transcription factors Sp-1, GATA-1, AML-1a, Lyf-1 and Ets-1, but there were no TATA or CAAT boxes within a 226-bp sequence upstream from the initiation codon. Primer extension analysis and 5'RACE (rapid amplification of cDNA 5' ends) identified multiple transcription initiation sites within the region -84 to -70 nucleotides from the first ATG codon in a Kozak consensus sequence. A core promoter region was determined by transfecting a series of deletion constructs with a dual luciferase reporter system into rat astrocyte-derived ACT-57 cells. We found that 226 bp of the core promoter region exhibited bidirectional promoter activity.

Asunto(s)