Direct synthesis of phenanthrenyl triflates from 1-biphenylyl-2-diazo-2-aryl ketones and triflic anhydride.

A strategy for direct synthesis of phenanthrenyl triflates from 1-biphenylyl-2-diazo-2-aryl ketones and triflic anhydride is described. The reaction of 1-biphenylyl-2-diazo-2-aryl ketones with triflic anhydride proceeded smoothly in the presence of 2,6-di-tert-butylpyridine under mild conditions to produce phenanthrenyl triflates in high to excellent yields. The phenanthrenyl triflate products were demonstrated to be utilized as coupling partners in various coupling reactions. The proposed mechanism involves an intramolecular Friedel-Crafts reaction of a vinyl cation intermediate formed in situ.

The mediating role of psychological capital on the relationship between perceived stress and self-directed learning ability in nursing students.

BACKGROUND: As indispensable reserves for the nursing workforce, undergraduate nursing students must possess self-directed learning abilities to consistently update their professional knowledge and adapt to the evolving demands of professional development. The acquisition of self-directed learning abilities can help undergraduate nursing students augment their theoretical knowledge and refine their clinical practice skills, thus fulfilling the demand from patients for high-quality nursing services. Hence, comprehending and investigating the factors that influence the development of self-directed learning abilities in nursing students is of paramount importance for nursing education and advancement of the nursing profession. OBJECTIVES: This study investigated the status of and associations between perceived stress, psychological capital, and self-directed learning abilities among undergraduate nursing students. Additionally, it examines the mediating role of psychological capital in the relationship between perceived stress and self-directed learning abilities. Thus, aiming to provide nursing educators with new directions for enhancing self-directed learning abilities. DESIGN: A cross-sectional descriptive study. METHODS: In February and March 2023, 900 undergraduate nursing students from 10 nursing schools completed an online questionnaire. The questionnaire included measures of perceived stress, psychological capital, and self-directed learning ability. Data were analyzed using SPSS 27.0 and the PROCESS macro tool. RESULTS: The scores for perceived stress, psychological capital, and self-directed learning ability among undergraduate nursing students were 40.07 ± 5.90, 99.89 ± 16.59, and 87.12 ± 9.20, respectively. Self-directed learning abilities were negatively correlated with perceived stress (r = -0.415, p < 0.001) and positively correlated with psychological capital (r = 0.465, p < 0.001). Perceived stress was negatively correlated with psychological capital (r = -0.630, p < 0.001). Psychological capital partially mediated the relationship between perceived stress and self-directed learning abilities among undergraduate nursing students, with a mediation effect of -0.166, accounting for 49.55% of the total effect. CONCLUSION: This study found that undergraduate nursing students perceived high levels of stress, possessed low levels of psychological capital, and had moderate levels of self-directed learning. Perceived stress and psychological capital directly influenced undergraduate nursing students' self-directed learning abilities, and perceived stress indirectly affected self-directed learning abilities through psychological capital. Nursing managers and educators should alleviate the perceived stress of undergraduate nursing students and cultivate their positive psychological capital to enhance self-directed learning abilities.

One-pot synthesis of multisubstituted propenylbenzenes from benzyl chlorides through relay catalysis of palladium.

A strategy for the synthesis of multisubstituted propenylbenzenes using benzyl chlorides as starting materials is described. The palladium-catalyzed allylative dearomatization and the subsequent Wagner-Meerwein rearrangement as well as the olefin isomerization proceeded smoothly under mild conditions to produce propenylation products in good yields with high regioselectivity. Control experiments and cyclic voltammetry analysis suggest that Bu3SnCl, a by-product generated in the first step of allylative dearomatization, plays an essential role in the third step of olefin isomerization in the presence of a Brønsted acid.

Bioleaching performance of vanadium-bearing smelting ash by Acidithiobacillus ferrooxidans for vanadium recovery.

The bioleaching process is widely used in the treatment of ores or solid wastes, but little is known about its application in the treatment of vanadium-bearing smelting ash. This study investigated bioleaching of smelting ash with Acidithiobacillus ferrooxidans. The vanadium-bearing smelting ash was first treated with 0.1 M acetate buffer and then leached in the culture of Acidithiobacillus ferrooxidans. Comparison between one-step and two-step leaching process indicated that microbial metabolites could contribute to the bioleaching. The Acidithiobacillus ferrooxidans demonstrated a high vanadium leaching potential, solubilizing 41.9% of vanadium from the smelting ash. The optimal leaching condition was determined, which was 1% pulp density, 10% inoculum volume, an initial pH of 1.8, and 3 Fe2+g/L. The compositional analysis showed that the fraction of reducible, oxidizable, and acid-soluble was transferred into the leaching liquor. Therefore, as the alternative to the chemical/physical process, an efficient bioleaching process was proposed to enhance the recovery of vanadium from the vanadium-bearing smelting ash.

Spirocarbocycle Synthesis from Chloromethylarenes via Transition-Metal-Catalyzed Allylative Dearomatization and Ring Closure Metathesis.

A strategy for the synthesis of spirocarbocycles by using chloromethyl arenes as starting materials is described in this paper. The palladium-catalyzed allylative dearomatization and the subsequent ruthenium-catalyzed ring closure metathesis proceeded smoothly under mild conditions to produce the corresponding spirocarbocycle products with moderate to high yields. Benzene-ring-, naphthalene-ring-, and anthracene-ring-containing substrates can be easily transformed into spirocarbocycles by using the proposed method.

Palladium-Catalyzed Para-C-H Bond Amination of 2-Aryl Chloromethylbenzenes.

Palladium-catalyzed para-C-H bond amination of 2-aryl chloromethylbenzenes is described for the first time. The reactions of 2-aryl chloromethylbenzenes with cyclic amines proceeded smoothly in the presence of Pd(acac)2, tri(2-furyl)phosphine, and NaH in tetrahydrofuran at 40 °C to provide para-C-H bond aminated products in satisfactory to high yields with acceptable regioselectivity in most cases. The electronic property of the substituents linked to the benzene rings did not significantly influence the reactivity of the 2-aryl chloromethylbenzene substrates and the reaction regioselectivity.

Mechanochemical treatment for degradation of ciprofloxacin (CIP) in solutions.

Ciprofloxacin (CIP) is a kind of widely used fluoroquinolone antibiotic, and the widespread presence of CIP in aquatic environment has become a serious issue. Mechanochemical treatment (MCT), as an effective approach to degrade persistent organic pollutants, has many advantages of low cost, simplicity, and being environmentally innocuous. However, little attention has been paid to employing MCT to treat effluents containing CIP. In this study, MCT was introduced to degrade CIP in aquatic solutions. A series of CIP degradation experiments were conducted by a planetary ball mill, and the influences of main parameters on CIP degradation efficiency were investigated. Furthermore, an optimum combination was selected through orthogonal experiments, and CIP degradation efficiency could reach as high as 99% in certain conditions. Besides, the biotoxicity of CIP solution was also studied. MCT exhibits satisfying performance for degrading CIP in solutions, which makes MCT a promising approach to CIP elimination and also encourages further applications in treating effluents containing other organic pollutants.

Investigations of S-nZVI/AC composites for hexavalent chromium (Cr(VI)) elimination: synthesis and application.

Sulfidated nano zero-valent iron supported by activated carbon (S-nZVI/AC) composites were synthesized via liquid phase reduction method, and then they were used for Cr(VI) elimination. Characterization results showed that Fe0 was the main component, besides, iron oxides and iron sulfides were also detected. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results showed that S-nZVI nanoparticles were homogeneously distributed on the surfaces of AC. The influences of S/Fe ratio, C/Fe ratio, pH value, reaction temperature and co-existed ions (Cl-, SO42-, PO43- and NO3-) on Cr(VI) removal performances were investigated. Furthermore, the corresponding mechanisms were also discussed. The S-nZVI/AC composites exhibited good aging-resistance performances that Cr(VI) removal efficiency still maintained at 83.1% after being sealed in water for seven days, and they also had satisfying cycling stabilities that Cr(VI) removal efficiency only decreased less than 10% after four cycles. The good performances of S-nZVI/AC composites for Cr(VI) removal are attributed to the protection effect of iron sulfides and immobilization effect of AC, making S-nZVI/AC as a promising candidate for Cr(VI) elimination in effluents.

Palladium-Catalyzed Tail-to-Tail Reductive Dimerization of Terminal Alkynes to 2,3-Dibranched Butadienes.

The palladium-catalyzed tail-to-tail reductive dimerization of terminal alkynes is described for the first time. Aromatic terminal alkynes bearing diverse and sensitive functional groups as well as aliphatic terminal alkynes are efficiently transformed to 2,3-dibranched butadienes. The key to achieve a selective tail-to-tail reductive dimerization reaction is to control appropriately the acidity of the reaction solution, which is accomplished by a combined use of pivalic acid and para-toluenesulfonic acid. The tail-to-tail reductive dimerization reaction is proposed to proceed via a cationic alkenyl palladium intermediate under acidic conditions.

Palladium-Catalyzed Three-Component Coupling Reaction via Benzylpalladium Intermediate.

Transition-metal catalyzed multi-component reactions have captured the attention of researchers in organic synthesis and drug synthesis due to their advantages of simple operation, easy availability of raw materials and without separation of intermediates. Among the multi-component reactions, the three-component processes have been developed into effective organic procedures. This personal account reviews our and other group's studies on the development of three-component coupling reaction for the rapid construction of two new chemical bonds simultaneously via benzylpalladium intermediates. Catalyst-switched three-component reactions of benzyl halides, activated olefins, and allyltributylstannane were successfully conducted to produce the corresponding benzylallylation products. Activation and conversion of carbon monoxide and carbon dioxide via π-benzylpalladium intermediates provide access to a wide range of unsaturated ketones and esters with excellent functional group tolerance. Meanwhile, other methods to produce benzylpalladium intermediates, including Heck insertion of alkenes into arylpalladium complexes, the oxidative addition of benzyl carbonate to palladium complexes and palladium-carbene migratory insertion, were also highlighted.

Chiral Indolizidine Synthesis through the Ir-Catalyzed Asymmetric Hydrogenation of Cyclic Pyridinium Salts.

The Ir-catalyzed asymmetric hydrogenation of cyclic pyridinium salts is presented as a new strategy for the convenient and efficient synthesis of chiral indolizidines. The asymmetric hydrogenation of cyclic pyridinium salts derived from 2-(2-acylphenyl)pyridines proceeded smoothly in the presence of [Ir(cod)Cl]2 and (R)-DM-SegPhos to provide the desired chiral 7,8-benzoindolizidines 6 in high to excellent yields with moderate enantioselectivity (up to 86:14 er) and excellent diastereoselectivity (>20:1 dr). The enantiomeric purity of 6j was increased to 92:8 through recrystallization.

Improved heterodyne system using double-passed acousto-optic frequency shifters for measuring the frequency response of photodetectors in ultrasonic applications.

The improved heterodyne system is presented to measure the frequency response of photodetectors (PDs) with bandwidth about 100 MHz utilized in ultrasonic applications. In order to eliminate the periodic oscillation following the frequency tuning of the acousto-optic frequency shifters (AOFSs) in the measurement results, the AOFSs' double-passed scheme in Michelson interferometer is used. Compared with the AOFSs' single-passed configuration in Mach-Zehnder interferometer, the double-passed scheme can avoid additional optical alignment during the process of the frequency tuning and then reduce its induced measurement uncertainty. With two double-passed AOFSs connected in parallel, the experimental setup is designed to demonstrate the feasibility of the improved heterodyne system in the frequency range from 500 kHz to 135 MHz. Experimental results with measurement uncertainty are provided and discussed.

Copper-Catalyzed One-Pot Synthesis of 1,3-Enynes from 2-Chloro-N-(quinolin-8-yl)acetamides and Terminal Alkynes.

A method for the chemo-, regio-, and stereoselective one-pot synthesis of 1,3-enynes is described. The reaction of 2-chloro-N-(quinolin-8-yl)acetamides with terminal alkynes proceeds smoothly in the presence of a copper catalyst at room temperature to produce (E)-1,3-enynes in satisfactory to excellent yields. The mechanism study reveals that the cross-dimerization of internal alkynes generated in situ with terminal alkynes proceeds via allene intermediates. The directing group 8-aminoquinoline plays a key role in the current selective synthesis of (E)-1,3-enynes.

Relationship between neuroticism and sleep quality among asthma patients: the mediation effect of mindfulness.

OBJECTIVE: The aims of this study were to investigate the prevalence of sleep disturbance; to validate the associations between neuroticism, mindfulness, and sleep quality; and to further examine whether mindfulness mediates the relationship between neuroticism and sleep quality among asthma patients. METHODS: This study was conducted with 193 asthma patients from outpatient clinics. They completed questionnaires including the neuroticism subscale of the Big Five Inventory (BFI), the Pittsburgh Sleep Quality Index (PSQI), and the Mindful Attention Awareness Scale (MAAS). Structural equation model was used to analyze the relationships among neuroticism, mindfulness, and sleep quality, with mindfulness as a mediator. RESULTS: The mean global PSQI score was 7.57 (SD = 3.25), and 69.9% of asthma patients reported poor sleep quality (cutoff score > 5). Structural equation model analysis showed that neuroticism was significantly associated with global PSQI scores (ß = 0.198, P = 0.006), and mindfulness (ß = - 0.408, P < 0.001), respectively; mindfulness was associated with global PSQI scores (ß = - 0.250, P = 0.006). Furthermore, mindfulness mediated the relationship between neuroticism and global PSQI scores, in which the mediation effect was 0.102 (- 0.408 × - 0.250), and the bootstrapped 95% CI did not include zero (0.032, 0.208, P = 0.021). CONCLUSIONS: Sleep disturbance is a serious health concern among asthma patients. This study illuminated the latent mediating mechanism of mindfulness on neuroticism and sleep quality, and implied that intervention and prevention programs on mindfulness might be beneficial in improving sleep quality in asthma patients.

Conditional effects of mindfulness on sleep quality among clinical nurses: the moderating roles of extraversion and neuroticism.

The present study aimed to examine the potential moderating role of personality traits in the psychological mechanisms by which mindfulness can lead to better sleep quality. A total of 172 oncology nurses participated in this study, and completed self-reported measures, including the Mindful Attention Awareness Scale (MAAS), Pittsburgh Sleep Quality Index (PSQI), and 44-item Big Five Inventory (BFI-44). Results showed that mindfulness was correlated with the global PSQI score (r = -0.281, p < 0.01).Trait extraversion and neuroticism moderated the mindfulness-sleep relationship. The simple slope analysis indicated that the negative relationship between mindfulness and the global PSQI score was only significant at higher levels of extraversion (ß = -0.419, p < 0.001) and lower levels of neuroticism (ß = -0.344, p = 0.001). Additionally, the Johnson-Neyman technique revealed that, within a specific region (extraversion values above 21.93 and/or neuroticism values below 23.78), mindfulness was significantly associated with the global PSQI score; beyond the value regions, the significant association was lost. It suggests that mindfulness might play a protective role against sleep disturbance only among certain oncology nurses. The findings are valuable for identifying those who are more vulnerable to sleep dysfunction and may aid in targeted intervention planning.

Gender differences in latent classes of sleep quality in community-dwelling adults based on the Pittsburgh sleep quality index.

This study investigated the latent classes of sleep quality based on the Pittsburgh Sleep Quality index (PSQI) in Chinese adults, and analyzed whether these latent classes differed between men and women. A total of 982 adults (age: 18-59 years) participated in the questionnaire survey, and the PSQI was used to assess sleep quality. Two latent classes of sleep quality were found in men, and the cut-off value of PSQI for predicting the poor sleep quality group was 6. Four latent classes were found in women, which were named 'good sleep', 'daytime dysfunction', 'inadequate sleep', and 'poor sleep', respectively. In women, the optimal cut-off values of the PSQI for predicting the poor and good sleep quality groups were 9 and 6, respectively. Women who were not included in the 'poor sleep' group but had a score not less than 2 in the 'sleep duration' or 'daytime dysfunction' dimensions of PSQI were classified into the 'inadequate sleep' group or the 'daytime dysfunction' group. The findings may benefit the identification of sleep problems and assist in more effective alleviation of these issues.

Direct Carbohydroxylation of Arylalkenes with Allylic Alcohols: Cooperative Catalysis of Copper, Silver, and a Brønsted Acid.

The cooperative catalysis of copper, silver, and Brønsted acid is presented as a new strategy for olefin functionalization. The catalytic direct carbohydroxylation of arylalkenes with allylic alcohols provided a straightforward and efficient approach for preparing 4,5-unsaturated alcohols. Synthetically useful functional groups, such as Cl, Br, carbonyl, and chloromethyl, remained intact during the functionalization reaction.

Influence of the frequency response of the photodetector on the heterodyne interferometer-based sound pressure standards in water.

The heterodyne interferometer has been used to realize the sound pressure unit directly and absolutely for underwater acoustics and ultrasound, which is considered as the primary standard of the hydrophone calibration instead of the reciprocity method. The widely used demodulation methods are the zero-crossing method and the arctangent method. Recent studies show that the frequency response of the utilized photodetector (PD) in the heterodyne interferometer also significantly influences the results of the sound pressure realization using the two demodulation methods, especially for the high-intensity focused ultrasound application, which is investigated in this paper. Simulations are performed to obtain general conclusions using different types of low-pass filters to simulate the nonideal frequency responses of the PD. Also, experimental results of the frequency response of the utilized PD are then used to analyze the induced relative error of the demodulated acoustic particle velocity so as to evaluate the related measurement uncertainty of the sound pressure realization. The simulation method is useful to choose the required PDs and evaluate the related measurement uncertainty induced by their frequency responses for the optical sound pressure standards and other optical measurement applications.

Unsupported Nanoporous Gold Catalyst for Chemoselective Hydrogenation Reactions under Low Pressure: Effect of Residual Silver on the Reaction.

For the first time, H-H dissociation on an unsupported nanoporous gold (AuNPore) surface is reported for chemoselective hydrogenation of C≡C, C═C, C═N, and C═O bonds under mild conditions (8 atm H2 pressure, 90 °C). Silver doping in AuNPore, which was inevitable for its preparation through a process of dealloying of Au-Ag alloy, exhibited a remarkable difference in catalytic activity between two catalysts, Au>99Ag1NPore and Au90Ag10NPore.The former was more active and the latter less active in H2 hydrogenation, while the reverse tendency was observed for O2 oxidation. This marked contrast between H2 reduction and O2 oxidation is discussed. Further, Au>99Ag1NPore showed a high chemoselectivity toward reduction of terminal alkynes in the presence of internal alkynes which was not achieved using supported gold nanoparticle catalysts and other previously known methods. Reductive amination, which has great significance in synthesis of amines due to its atom-economical nature, was also realized using Au>99Ag1NPore, and the Au>99Ag1NPore/H2 system showed a preference for the reduction of aldehydes in the presence of imines. In addition to this high chemoselectivity, easy recovery and high reusability of AuNPore make it a promising heterogeneous catalyst for hydrogenation reactions.

Isoquinolone synthesis through S(N)Ar reaction of 2-halobenzonitriles with ketones followed by cyclization.

An efficient method for the synthesis of isoquinolones through base KO(t)Bu-promoted S(N)Ar reaction of 2-halobenzonitriles with ketones followed by Lewis acid Cu(OAc)2-catalyzed cyclization is described. Isoquinolone derivatives were obtained in satisfactory to good yields.