Environmental-friendly, flexible silk fibroin-based film as dual-responsive shape memory material.

Bio-based shape memory materials have attracted wide attention due to their biocompatibility, degradability and safety. However, designing and manufacturing wearable bio-based shape memory films with excellent flexibility and toughness is still a challenge. In this work, silk fibroin substrate with a ß-sheet structure was combined with a tri-block shape memory copolymer to prepare a transparent composited shape memory film. The silk fibroin-based film showed a dual-responsive shape memory function, which can respond to both temperature and water stimuli. This film has a sensitive water-responsive shape memory, which starts deforming after exposure to water for 3 s and fully recovers in 30 s. In addition, the composite film shows highly stretchable (>300 %) and could maintain its high tensile properties after 5 cycles of regeneration. The films also exhibited rapid degradation ability. This study provides new insights for the design of dual-responsive shape memory materials by combining biocompatible matrix and multi-block SMP to simultaneously enhance the mechanical properties, which can be used for intelligent packaging, medical supplies, soft actuators and wearable devices.

Promotion of self-directed learning abilities among Chinese medical students through preparing for career calling and enhancing teaching competencies in medical education: a cross-sectional study.

BACKGROUND: Medical students face a heavy burden as they are tasked with acquiring a vast amount of medical knowledge within a limited time frame. Self-directed learning (SDL) has become crucial for efficient and ongoing learning among medical students. However, effective ways to foster SDL ability among Chinese medical students are lacking, and limited studies have identified factors that impact the SDL ability of medical students. This makes it challenging for educators to develop targeted strategies to improve students' SDL ability. This study aims to assess SDL ability among Chinese medical students and examine the effects of career calling and teaching competencies on SDL ability, as well as the possible mechanisms linking them. METHODS: Data were collected from 3614 respondents (effective response rate = 60.11%) using cross-sectional online questionnaires and analyzed using IBM SPSS Statistics 22.0. The questionnaire comprised a Demographic Characteristics Questionnaire, Self-directed Learning Ability Scale (Cronbach's alpha = 0.962), Teaching Competencies Scale, and Career Calling Scale. RESULTS: The average SDL ability score of Chinese medical students was 3.68 ± 0.56, indicating a moderate level of SDL ability. The six factors of the Self-directed Learning Ability Scale-self-reflection, ability to use learning methods, ability to set study plans, ability to set studying objectives, ability to adjust psychological state, and willpower in studying-accounted for 12.90%, 12.89%, 12.39%, 11.94%, 11.34%, and 8.67% of the variance, respectively. Furthermore, career calling was positively associated with SDL learning ability (ß = 0.295, p < 0.001), and SDL learning ability was positively associated with teaching competencies (ß = 0.191, p < 0.01). Simple slope analysis showed that when the level of teaching competencies was higher, the influence of career calling on SDL ability was stronger. CONCLUSIONS: Chinese medical students' SDL ability has room for improvement. Medical students could strengthen their willpower in studying by setting milestones goals with rewards, which could inspire their motivation for the next goals. Teachers should guide students to learn experience to improve students' reflective ability. Educators play a crucial role in bridging the gap between career calling education and SDL ability enhancement, highlighting the significance of optimal teaching competencies. Colleges should focus on strengthening teachers' sense of career calling and teaching competencies.

Gemological characteristics and inclusions of green rutilated quartz from Huanggangliang, Inner Mongolia.

Normally, various minerals exist in quartz as inclusions. In this study, methods such as gem microscopy, polarizing microscopy, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and electron probe microanalysis (EPMA) were used to systematically study the gemological characteristics and inclusions in green rutilated quartz from Inner Mongolia. Results show that the sample appears green due to the chaotic distribution of green inclusions in the shape of hair filaments. Combined with the chemical composition, the inclusions are Ca-Fe-rich amphiboles with compositions very close to those of the end-member ferro-actinolite. According to the principle of amphibole nomenclature, the inclusions are named ferro-actinolite in the subclass of calc-alkaline amphiboles with a few named ferro-hornblende. Results suggested that the inclusions in green rutilated quartz were formed during the late stage of quartz crystallization. This work provides a new theoretical basis for the study of green rutilated quartz in Huanggangliang, Inner Mongolia.

The conservation of allelic DNA methylation and its relationship with imprinting in maize.

Genomic imprinting refers to allele-specific expression of genes depending on parental origin, and it is regulated by epigenetic modifications. Intraspecific allelic variation for imprinting has been detected; however, the intraspecific genome-wide allelic epigenetic variation in maize and its correlation with imprinting variants remain unclear. Here, three reciprocal hybrids were generated by crossing Zea mays inbred lines CAU5, B73, and Mo17 in order to examine the intraspecific conservation of the imprinted genes in the kernel. The majority of imprinted genes exhibited intraspecific conservation, and these genes also exhibited interspecific conservation (rice, sorghum, and Arabidopsis) and were enriched in some specific pathways. By comparing intraspecific allelic DNA methylation in the endosperm, we found that nearly 15% of DNA methylation existed as allelic variants. The intraspecific whole-genome correlation between DNA methylation and imprinted genes indicated that DNA methylation variants play an important role in imprinting variants. Disruption of two conserved imprinted genes using CRISPR/Cas9 editing resulted in a smaller kernel phenotype. Our results shed light on the intraspecific correlation of DNA methylation variants and variation for imprinting in maize, and show that imprinted genes play an important role in kernel development.

Hollow MIL-125 Nanoparticles Loading Doxorubicin Prodrug and 3-Methyladenine for Reversal of Tumor Multidrug Resistance.

Multidrug resistance (MDR) is a key factor in chemotherapy failure and tumor recurrence. The inhibition of drug efflux and autophagy play important roles in MDR therapy. Herein, a multifunctional delivery system (HA-MIL-125@DVMA) was prepared for synergistically reverse tumor MDR. Tumor-targeted hollow MIL-125-Ti nanoparticles were used to load the doxorubicin-vitamin E succinate (DV) prodrug and 3-methyladenine (3-MA) to enhance reverse MDR effects. The pH-sensitive DV can kill tumor cells and inhibit P-gp-mediated drug efflux, and 3-MA can inhibit autophagy. HA-MIL-125@DVMA had uniformly distributed particle size and high drug-load content. The nanoparticles could effectively release the drugs into tumor microenvironment due to the rapid hydrazone bond-breaking under low pH conditions, resulting in a high cumulative release rate. In in vitro cellular experiments, the accumulation of HA-MIL-125@DVMA and HA-MIL-125@DV in MCF-7/ADR cells was significantly higher than that in the control groups. Moreover, the nanoparticles significantly inhibited drug efflux in the cells, ensuring the accumulation of the drugs in cell cytoplasm and causing drug-resistant cells' death. Importantly, HA-MIL-125@DVMA effectively inhibited tumor growth without changes in body weight in tumor-bearing mice. In summary, the combination of the acid-sensitive prodrug DV and autophagy inhibitor 3-MA in a HA-MIL-125 nanocarrier can enhance the antitumor effect and reverse tumor MDR.

Controlling the Fluorescence Behavior of Hydrophobic Pigments by Supramolecular Self-Assembling on Organic Layered Silicate Minerals.

This research focused on the supramolecular self-assembly of organic fluorescent molecules on organically modified layered silicate minerals to design and prepare layered nanocomposites with excellent fluorescence properties. Aromatic hydrocarbons are hydrophobic and poorly loaded on the hydrophilic surface of layered silicate minerals, but they are easily captured by an organically modified mineral surface. Montmorillonite (MMT) and saponite (SAP), typical 2:1 type layered silicate minerals with different octahedral cations, were modified with the cationic surfactant octadecyl trimethylammonium chloride (OTAC) and loaded with pyrene (an aromatic hydrocarbon dye) with different molar ratios to the cationic surfactant by supramolecular self-assembling to construct fluorescent nanocomposites. The effect of pyrene concentration and the octahedral cation of the 2:1 type layered silicate minerals on photoluminescence properties was investigated. The fluorescence spectra of the nanocomposites prepared under low pyrene concentrations showed two bands at around 400 and 470 nm, corresponding to the monomer and excimer emissions; the band intensity of the excimer shoots up with the increase of pyrene concentration, reflecting different contributions from monomer and dimer species and the formation of radical aggregates. The excellent heat resistance of the layered silicate structure can effectively protect pyrene molecules from external environmental influences.

Structures and Biological Activities of Secondary Metabolites from the Trichoderma genus (Covering 2018-2022).

Trichoderma, a genus with more than 400 species, has a long history of use as an industrial bioreactor, biofertilizer, and biocontrol agent. It is considered a significant source of secondary metabolites (SMs) that possess unique structural features and a wide range of bioactivities. In recent years, numerous secondary metabolites of Trichoderma, including terpenoids, polyketides, peptides, alkaloids, and steroids, have been identified. Most of these SMs displayed antimicrobial, cytotoxic, and antifungal effects. This review focuses on the structural diversity, biological activities, and structure-activity relationships (SARs) of the SMs isolated from Trichoderma covered from 2018 to 2022. This study provides insights into the exploration and utilization of bioactive compounds from Trichoderma species in the agriculture or pharmaceutical industry.

Patient satisfaction with humanistic nursing in Chinese secondary and tertiary public hospitals: a cross-sectional survey.

Background: Humanistic care pertains to the abilities, attitudes, and behaviors central to patient-centered care, contributing to patients' sense of safety and wellbeing. This study aimed to assess the satisfaction of patients with humanistic nursing care in Chinese secondary and tertiary public hospitals. Methods: A national cross-sectional survey was conducted across 30 provinces and 83 hospitals in China. Patient satisfaction with humanistic care was assessed using the Methodist Health Care System Nurse Caring Instrument (NCI), which encompasses 20 items across 12 dimensions. Each item was rated on a 7-point Likert scale, yielding a total score of 140. Multiple linear regression analysis was employed to identify factors associated with patients' satisfaction. Results: Moderate satisfaction (mean score 91.26 ± 13.14) with humanistic nursing care was observed among the 17,593 participants. Factors significantly associated with patient satisfaction included age, hospital type, presence of children, educational attainment, place of residence, family monthly income, and medical insurance type. Conclusion: The study findings highlight the importance of tailored interventions, evidence-based practice guidelines, and patient-centered care in improving patients' satisfaction with humanistic nursing care. Continuous emphasis on nursing education and professional development is crucial for enhancing humanistic care and patient satisfaction.

Block-based teaching method based on cybernetics: a trial with 115 Chinese undergraduate medical students.

BACKGROUND: Class attendance is important for academic performance. Personal interactions between teachers and students are difficult in large classes; the number of medical undergraduate students in China ranges from dozens to over 100. It is important for teachers to control the teaching process to improve student attendance and participation. METHODS: Two classes of fourth-year undergraduate medical students, with each class comprising 115 students, participated in the study. One class, the trial group, was taught by the block-based teaching method based on cybernetics. This study was conducted with three of the courses in the Introduction to Oncology subject, and the trial group's courses included several blocks. Each block had a test paper that the students responded to immediately in class using the Internet. The teacher obtained feedback from the students when the rate of correct responses to block-test questions was less than 90%. The teacher adjusted the teaching in the following blocks according to the feedback information. The other class, the control group, was taught using the traditional lecture-based teaching method. RESULTS: The average attendance in the trial group was 104/115 (90.43%), and that in the control group was 83/115 (72.17%) (p = 0.0003). The teacher adjusted the teaching three times in the radiotherapy course owing to the complex ideas. After feedback, information on chemotherapy for the upper body was adjusted once, as was that on chemotherapy for the lower body, owing to students' attitudes. The average total score of the trial group was 86.06 ± 17.46 and that of the control group was 80.38 ± 6.97 (p = 0.041). Questionnaire I showed that the trial group students' attendance and participation were better than in the control group. Questionnaire II showed that the block-based teaching method based on cybernetics was approved by the students. CONCLUSIONS: The block-based teaching method based on cybernetics used in medical classes with large numbers of Chinese undergraduate students had positive effects.

Ionic liquid-based ultrasonic-assisted extraction coupled with HPLC to analyze isoquercitrin, trifolin and afzelin in Amygdalus persica L. flowers.

This study aimed to establish a method for the simultaneous determination of isoquercitrin, trifolin and afzelin in A. persica flowers by high performance liquid chromatography (HPLC) with ionic liquid as extractant and ultrasonic-assisted extraction. The effects of ionic liquid concentration, solid-liquid ratio, number of crushing mesh, ultrasonic time, extraction temperature, and ultrasonic power on the extraction yield of three target compounds were investigated using the extraction yield of target analytes as the index. According to the results of single factor experiment, the Box-Behnken design-response surface methodology (BBD) was used to optimize the extraction method and compared with the traditional extraction method. The results showed that, calibration curves had excellent linearity (R2 > 0.9990) within the test ranges. In combination with other validation data, this method demonstrated good reliability and sensitivity, and can be conveniently used for the quantification of isoquercitrin, trifolin and afzelinin A. persica flowers. And the contents of isoquercitrin, trifolin and afzelin were 64.08, 20.55 and 75.63 µg/g, respectively. The optimal process obtained by BBD was as follows: ionic liquid concentration was 1.0 mol/L, solid-liquid ratio was 1:40 g/ml, mesh sieve was 50 mesh, ultrasonic time was 40 min, extraction temperature was 50 °C, and ultrasonic power was 400 W. Under the optimal conditions, the theoretical predicted total extraction yield of the three target compounds was 159.77 µg/g, which was close to the actual extraction value (160.26 µg/g, n = 3), this result indicating that the optimal process parameters obtained by response surface methodology analysis were accurate and reliable. The method was simple, accurate and rapid for determination the contents of three active ingredients in A. persica flowers.

Vacancy-Enhanced Self-Reduction of Eu in Pyrophosphate Phosphor.

The self-reduction mechanism in pyrophosphate phosphors is currently explained through nonequivalent substitution for charge compensation. Nevertheless, the impact of oxygen vacancies on the self-reduction enhancement requires further investigation. Herein, heterovalent Ba1-xZn1-yP2O7:xEu2+/3+, yMg phosphors with rigid structures were prepared through conventional solid-phase technology in air. The cation substitution strategy leads to different chemistry electronegativity and adjustable crystal field environments and creates vacancy defects. Crystal structure and component analysis indicate the gradual phase segregation change from BaZnP2O7 to BaMgP2O7 with increasing Mg2+ content. The CIE coordinates that are tuned from (0.514, 0.334) to (0.326, 0.152) and realize color-tunable emission from red-orange to blue-violet can be used as multicolor functional materials. Besides, the phosphor demonstrates its maximum Sa of 0.4725% K-1 (498 K) and Sr of 1.376% K-1 (423 K). These results demonstrate that the phosphors have the potential for contactless optical temperature measurement and anticounterfeiting. This work not only investigates the self-reduction of the Eu3+ → Eu2+ phenomenon but also provides a supplementary explanation and data support to complete the effect of the oxygen vacancy on self-reduction.

Characterization of Genes That Exhibit Genotype-Dependent Allele-Specific Expression and Its Implications for the Development of Maize Kernel.

Heterosis or hybrid vigor refers to the superior phenotypic traits of hybrids relative to their parental inbred lines. An imbalance between the expression levels of two parental alleles in the F1 hybrid has been suggested as a mechanism of heterosis. Here, based on genome-wide allele-specific expression analysis using RNA sequencing technology, 1689 genes exhibiting genotype-dependent allele-specific expression (genotype-dependent ASEGs) were identified in the embryos, and 1390 genotype-dependent ASEGs in the endosperm, of three maize F1 hybrids. Of these ASEGs, most were consistent in different tissues from one hybrid cross, but nearly 50% showed allele-specific expression from some genotypes but not others. These genotype-dependent ASEGs were mostly enriched in metabolic pathways of substances and energy, including the tricarboxylic acid cycle, aerobic respiration, and energy derivation by oxidation of organic compounds and ADP binding. Mutation and overexpression of one ASEG affected kernel size, which indicates that these genotype-dependent ASEGs may make important contributions to kernel development. Finally, the allele-specific methylation pattern on genotype-dependent ASEGs indicated that DNA methylation plays a potential role in the regulation of allelic expression for some ASEGs. In this study, a detailed analysis of genotype-dependent ASEGs in the embryo and endosperm of three different maize F1 hybrids will provide an index of genes for future research on the genetic and molecular mechanism of heterosis.

Anti-IAV indole-diterpenoids from the marine-derived fungus Penicillium citrinum.

A new indole-diterpenoid, penijanthine E (1), and a known analogue (2), were obtained from the PDB culture of the marine-derived fungus Penicillium citrinum ZSS-9. The absolute configuration of 1 was elucidated by calculated TDDFT ECD and DP4plus calculations. The absolute configuration of 2 was confirmed by single-crystal X-ray diffraction analysis and TDDFT ECD calculations. Compounds 1 and 2 showed antiviral activity against influenza A virus (IAV) of A/WSN/33(H1N1) and A/PR/8/34(H1N1) strains with IC50 values ranging from 12.6 to 46.8 µM.

Peimine Inhibits MCF-7 Breast Cancer Cell Growth by Modulating Inflammasome Activation: Critical Roles of MAPK and NF-κB Signaling.

OBJECTIVE: Peimine (PM) is a bioactive compound obtained from Fritillaria. It has been documented that PM exhibits potent antitumor properties against multiple cancers. However, the antitumor properties of PM in breast cancer and its associated mechanisms have not been clarified. METHODS: Proliferation and apoptosis of MCF-7 and MCF-10A cells were detected by CCK8, colony formation, and flow cytometry assays. Cytotoxicity was measured by Lactate dehydrogenase (LDH) leakage assay. The level of IL-1ß and IL-18 were detected with ELISA kits. Western blotting and real-time Polymerase Chain Reaction were performed to analyze the expression of proteins and genes related to the NLRP3 inflammasome pathway and Endoplasmic reticulum stress. RESULTS: The doses of PM (5, 10, and 20 µM) inhibited cell viability significantly, apoptotic induction, and inflammasome activation in breast cancer cells in vitro. Inflammasome components were decreased, including the apoptosisassociated speck like protein containing a CARD (ASC) and NOD-like receptor pyrindomain-containing protein3 (NLRP3), as well as the inhibition of caspase-1 and interleukin-1ß activation. Moreover, inflammasome inhibitors suppressed cell growth and induced apoptosis, implying that PM suppresses the growth of breast cancer cells through regulating inflammasome. Mechanistically, PM inhibited the activity of inflammasome by alleviating endoplasmic reticulum (ER) stress and by down-regulating the expression of multiple proteins in transcription factor nuclear factor- κB (NF-κB) and mitogen-activated protein kinases (MAPKs) signaling pathways. CONCLUSION: These findings show that PM suppresses the growth of breast cancer cells by inhibiting inflammasome activation, to a certain extent, by primarily acting on the MAPK/NF-κB pathway's inactivation-dependent mechanisms.

Bioactive cytochalasans from the desert soil-derived fungus Chaetomium madrasense 375 obtained via a chemical engineering strategy.

The chemical engineering of natural extracts has emerged as an effective strategy for the production of diverse libraries of chemicals, making it integral to drug discovery. A chemical engineering strategy based on the epoxidation and ring-opening reactions was used to prepare diversity-enhanced extracts of Chaetomium madrasense 375. Eleven unnatural cytochalasan derivatives (1-11) with unique functional groups, such as amine and isoxazole, were isolated and characterized from these chemically engineered extracts of C. madrasense 375. The identification of these new structures was accomplished through comprehensive spectroscopic analysis, supplemented by synthetic considerations. Notably, compounds 5 and 13-16 displayed potent phytotoxic effects on Arabidopsis thaliana, while compounds 1, 2, 5, 10, and 12 demonstrated inhibitory activities on LPS-induced NO production in RAW264.7 cells. Among them, compound 1 was found to be able to inhibit the upregulated expression of the inducible nitric oxide synthase (iNOS) protein induced by LPS, while also decreasing the production of pro-inflammatory cytokines (IL-6) and influencing the phosphorylation of p38, ERK1/2, and JNK at 100 µM. Our findings demonstrate that the chemical engineering of natural product extracts can be an efficient technique for the generation of novel bioactive molecules.

Conservation Study of Imprinted Genes in Maize Triparental Heterozygotic Kernels.

Genomic imprinting is a classic epigenetic phenomenon related to the uniparental expression of genes. Imprinting variability exists in seeds and can contribute to observed parent-of-origin effects on seed development. Here, we conducted allelic expression of the embryo and endosperm from four crosses at 11 days after pollination (DAP). First, the F1 progeny of B73(♀) × Mo17(♂) and the inducer line CAU5 were used as parents to obtain reciprocal crosses of BM-C/C-BM. Additionally, the F1 progeny of Mo17(♀) × B73(♂) and CAU5 were used as parents to obtain reciprocal crosses of MB-C/C-MB. In total, 192 and 181 imprinted genes were identified in the BM-C/C-BM and MB-C/C-MB crosses, respectively. Then, by comparing the allelic expression of these imprinted genes in the reciprocal crosses of B73 and CAU5 (BC/CB), fifty-one Mo17-added non-conserved genes were identified as exhibiting imprinting variability. Fifty-one B73-added non-conserved genes were also identified by comparing the allelic expression of imprinted genes identified in BM-C/C-BM, MB-C/C-MB and MC/CM crosses. Specific Gene Ontology (GO) terms were not enriched in B73-added/Mo17-added non-conserved genes. Interestingly, the imprinting status of these genes was less conserved across other species. The cis-element distribution, tissue expression and subcellular location were similar between the B73-added/Mo17-added conserved and B73-added/Mo17-added non-conserved imprinted genes. Finally, genotypic and phenotypic analysis of one non-conserved gene showed that the mutation and overexpression of this gene may affect embryo and kernel size, which indicates that these non-conserved genes may also play an important role in kernel development. The findings of this study will be helpful for elucidating the imprinting mechanism of genes involved in maize kernel development.

Chaetoglobosin E inhibits tumor growth and promotes the anti-tumor efficacy of cytotoxic drugs in esophageal squamous cell carcinoma by targeting PLK1.

Background: Currently, there is no satisfactory treatment available for esophageal squamous cell carcinoma (ESCC), and thus, there is a pressing need to develop effective drugs. Chaetoglobosin E, a cytochalasan alkaloid derived from metabolites of Chaetomium madrasense 375, is a chaetoglobosin with intense anti-tumor activity. Therefore, revealing its anti-tumor mechanism for the application of cytochalasans is crucial. Methods: The cytotoxic effect of chaetoglobosin E and cisplatin on esophageal cancer KYSE-30, KYSE-150, and TE-1 cells was detected using cell viability or colony formation assays. The cell cycle, apoptosis, autophagy, invasion, and metastasis were assayed by flow cytometry or western blot. The potential target of chaetoglobosin E was assayed by RNA sequencing (RNA-seq) and large loop prediction software analysis and was assessed by western blot and real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). The effect of its target on cell pyroptosis was assayed using overexpression and silence experiments. Results: Chaetoglobosin E significantly inhibited the proliferation of KYSE-30, KYSE-150, and TE-1 cells, especially KYSE-30 cells. Our results showed that chaetoglobosin E induced the G2/M phase arrest of KYSE-30 cells, followed by the down-regulation of cyclinB1, CDC2, and p-CDC2, and up-regulation of p21. Moreover, chaetoglobosin E also decreased the anti-apoptotic protein expression of Bcl-2, increased apoptotic expression of Bax, increased autophagy protein expressions of beclin1 and LC3, decreased invasion and metastasis protein expression of E-cadherin, and increased expression of vimentin. The RNA-seq and large loop prediction software analysis results indicated that its potential target might be polo-like kinase 1 (PLK1). Moreover, results also showed that chaetoglobosin E can reverse the PLK1 overexpression plasmid-induced up-regulation of the PLK1 protein. Furthermore, we found that chaetoglobosin E induced pyroptosis via the activation of the gasdermin E (GSDME) protein. Further studies showed that the high expression of PLK1 inactivated the GSDME protein, while the knockdown of PLK1 expression activated the GSDME protein, indicating that chaetoglobosin E induced cell pyroptosis by inhibiting PLK1. Conclusions: This study suggested that chaetoglobosin E may be a novel lead compound to the treatment of ESCC patients by targeting PLK1, and elucidated for the first time that PLK1 was involved in a new pyroptosis mechanism.

Water characterization and structural attribution of different colored opals.

The structure type and water content of opal will affect its stability and value. When the structure is Opal-A type, its value is higher. When the water content is high, its stability will decrease. The structural attribution and water distribution of pink, yellow, green, blue and purple opal have been investigated by several methodologies like powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transform near infrared spectroscopy (FT-NIR). The results show that all the opal samples are CT type, among which the green sample has the highest crystallinity. The water contents of the opals range from 3.06 to 8.78%. The distribution and quantity of molecular water (H2Omol) and silanols (H2OSiOH) are calculated semi-quantitatively according to intensity of 4500 cm-1 and 5200 cm-1 peaks in the near infrared region, and it is found that the water in all the samples is basically composed of molecular water. The precipitation mechanism for opal formation results in different structural types, and the difference in structural composition leads to different water contents. This work provides a theoretical basis for the future study of the opal metallogenic environment.

Study of the mechanism of color change of prehnite after heat treatment.

The most common color of prehnite is green, while yellow prehnite is rare and precious. Heat treatment is usually an effective way to improve the color of gemstones, but whether heat treatment can improve the color of prehnite remains to be explored. In this paper, yellow-green prehnite samples were heat-treated under oxidizing and reducing atmospheres, and the composition, structure and chromogenic mechanism of the prehnite samples before and after the heat treatment were analyzed and summarized by means of X-ray Fluorescence Spectroscopy (XRF), X-ray diffractomer (XRD), in situ high temperature XRD, Fourier Transform Infrared Spectroscopy (FTIR), Micro-Raman Spectroscopy, UV-Vis Spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results show that the change of the relative content and occupation position of Fe2+ and Fe3+ is the main reason for the color change of yellow-green prehnite. When the yellow-green prehnite is heated to 800 °C, in an oxidizing atmosphere, some of the Fe2+ is oxidized to Fe3+, the content of Fe3+ increases, and the color becomes brownish yellow; in a reducing atmosphere, some of the Fe3+ is reduced to Fe2+, the content of Fe2+ increases, and the color becomes grayish white. The UV-Vis absorption spectra of the oxidized and reduced samples at this temperature further showed that the absorption broadband at 520-700 nm caused by the charge transfer between Fe2+ and Fe3+ disappeared, resulting in a great change in the color of the prehnite. Our experimental model provides ideas and experimental data for the further study of prehnite heat treatment.