Efficacy and Neural Mechanisms of Mindfulness Meditation Among Adults With Internet Gaming Disorder: A Randomized Clinical Trial.

Importance: The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR), recently identified internet gaming disorder (IGD) as a condition warranting more research, and few empirically validated treatments exist. Mindfulness meditation (MM) has multiple health benefits; however, its efficacy in treating IGD and potential neural mechanisms underlying MM treatment of the disorder remain largely unknown. Objective: To explore the efficacy of MM used to treat adults with IGD and to identify neural mechanisms underlying MM. Design, Setting, and Participants: This randomized clinical trial was performed from October 1 to November 30, 2023, at Hangzhou Normal University in Hangzhou, China. Adults (aged ≥18 years) who met at least 6 of the 9 DSM-5-TR proposed criteria for IGD were recruited to receive either MM or progressive muscle relaxation (PMR). Data analysis was performed on December 1, 2023. Intervention: Participants underwent MM training (an 8-session meditation program that focuses on attention and acceptance) and PMR training (an 8-time program for body relaxation) delivered in groups that met 2 times each week for 4 weeks. Main Outcomes and Measures: This per-protocol analysis included only participants who finished the pretest assessment, 8 training sessions, and posttest assessment. The main outcomes were addiction severity (measured with the DSM-5-TR proposed criteria for IGD and with Internet Addiction Test scores), gaming craving (measured with Questionnaire for Gaming Urges scores), and blood oxygen level-dependent signals assessed with cue-craving tasks on fMRI. Behavioral and brain measurements were compared using analysis of variance. Functional connectivity (FC) among identified brain regions was measured to test connectivity changes associated with MM. Results: This study included 64 adults with IGD. A total of 32 participants received MM (mean [SD] age, 20.3 [1.9] years; 17 women [53%]) and 32 received PMR (mean [SD] age, 20.2 [1.5] years; 16 women [50%]). The severity of IGD decreased in the MM group (pretest vs posttest: mean [SD], 7.0 [1.1] vs 3.6 [0.8]; P < .001) and in the PMR group (mean [SD], 7.1 [0.9] vs 6.0 [0.9]; P = .04). The MM group had a greater decrease in IGD severity than the PMR group (mean [SD] score change for the MM group vs the PMR group, -3.6 [0.3] vs -1.1 [0.2]; P < .001). Mindfulness meditation was associated with decreased brain activation in the bilateral lentiform nuclei (r = 0.40; 95% CI, 0.19 to 0.60; P = .02), insula (r = 0.35; 95% CI, 0.09 to 0.60; P = .047), and medial frontal gyrus (MFG; r = 0.43; 95% CI, 0.16 to 0.70; P = .01). Increased MFG-lentiform FC and decreased craving (pretest vs posttest: mean [SD], 58.8 [15.7] vs 33.6 [12.0]; t = -8.66; ƞ2 = 0.30; P < .001) was observed after MM, and changes in MFG-lentiform FC mediated the relationship between increased mindfulness and decreased craving (mediate effect, -0.17; 95% CI, -0.32 to -0.08; P = .03). Conclusions and Relevance: In this study, MM was more effective in decreasing addiction severity and gaming cravings compared with PMR. These findings indicate that MM may be an effective treatment for IGD and may exert its effects by altering frontopallidal pathways. Trial Registration: Chinese Clinical Trial Registry Identifier: ChiCTR2300075869.

Mindfulness Meditation Training Reduces Gaming Cravings by Reshaping the Functional Connectivity Between the Default Mode Network and Executive Control-Related Brain Regions.

BACKGROUND: Internet gaming disorder (IGD) can lead to psychological problems and cause behavioral problems in individuals. Traditional interventions have been ineffective in treating IGD. Meanwhile, mindfulness meditation (MM) is an emerging method that has proven to be effective for treating psychiatric disorders. In this study, MM was used to intervene in IGD and to explore its neural mechanism. METHODS: Eighty participants were recruited through advertisements. Eventually, 61 completed the 1-month training (MM group, n = 31; progressive muscle relaxation [PMR] group, n = 30), including a pretest, 8 training sessions, and a posttest. Regional homogeneity and degree centrality were calculated, and the tests (pre- and post-) and group (MM and PMR) analysis of variance was performed. The overlapping results were obtained as region of interest for functional connectivity (FC) analyses. Behavioral data and neurotransmitter availability maps were correlated with FC. RESULTS: Compared with PMR, MM decreased the severity of addiction and game craving in IGD. Brain imaging results showed that the FC between and within the executive control and default mode networks/reward-related regions were enhanced. Significant negative correlations were observed between FC and dopamine receptor D2, dopamine transporter, and vesicular acetylcholine transporter. Significant positive correlations were observed between FCs and serotonin and aminobutyric acid receptors. CONCLUSIONS: This study confirmed the effectiveness of MM in treating IGD. MM altered the default mode and enhanced top-down control over game cravings. These findings were revealed by the correlations between brain regions and behavioral and biochemical effects. The results show the neural mechanism of MM in reducing IGD and lay the foundation for future research.

Theoretical investigations on CL-20/ANTA co-crystal explosive via molecular dynamics method.

CONTEXT: The study of CL-20 co-crystal has always been a focal point within the field of energetic material modification. In this study, we employed a combination of density functional theory and molecular dynamics simulations to investigate the properties of hexanitrohexaazaisowurtzitane (CL-20)/3-amino-5-nitro-1,2,4-triazole (ANTA) with different molar ratios ranging from 4:1 to 1:4. Additionally, EXPLO-5 software utilized to predict the detonation properties and products of pure CL-20, ANTA, and CL-20/ANTA systems. The results revealed that there was an interaction between CL-20 and ANTA molecules, which had the potential to form a co-crystal. The most likely molar ratio for co-crystal formation was 1:1, and the main driving forces for co-crystal formation were electrostatic force, dispersion force, and van der Waals force. The co-crystal explosive exhibited moderate sensitivity and excellent mechanical properties. Furthermore, the co-crystal detonation performance at a molar ratio of 1:1 was between that of CL-20 and ANTA, representing a new type of insensitive high-energy material. METHODS: The properties of CL-20/ANTA co-crystal were predicted by molecular dynamics (MD) method under Materials Studio software. For the whole MD simulations, set the temperature at 298 K, and the pressure was 0.0001 GPa. Conducted MD simulation under the NPT ensemble for a total simulation duration of 1 ns. The first 0.5 ns was used for thermodynamic equilibrium, and the last 0.5 ns was used for statistical calculation and analysis. Sampling was recorded every 10 fs during the calculation.

Validation of online mindfulness-enhanced course for stress reduction in teachers.

Background: Mindfulness-based interventions have gained popularity as a means of reducing stress and increasing resilience among the preclinical population. The present study aimed to investigate the effects of an online mindfulness-enhanced course on stress reduction in teachers, especially since online learning and teaching have been frequently applied to respond to emergencies such as COVID-19-relevant school suspension. Methods: The study consisted of two phases. Phase 1 aimed to explore the relationship between teachers' perceived stress and mindfulness traits. In total of 6,252 teachers completed assessments of stress symptoms using the Chinese Perceived Stress Scale (CPSS) and occupational stress sources, as well as mindfulness using the Five Factor Mindfulness Questionnaire (FFMQ). Phase 2 aimed to examine the effectiveness of the online mindfulness-enhanced course. In total of 132 teachers were randomly assigned to either receive a 3-week online mindfulness course specifically designed for stress reduction and emotion regulation (N = 66) or a matched active control group (N = 66) and their pre-training and post-training self-reported states (e.g., perceived stress, mindfulness level, practice time) were measured. Results: The detection rate of Health Risk Stress (≥26 scores) was as high as 61.72%, and a negative association between the score of FFMQ and perceived stress level was found. Importantly, compared to the control group, the mindfulness training group showed a significant decrease in perceived stress and negative emotion, as well as an increase in understanding of the core mechanisms of mindfulness after training. Additionally, individual improvement in FFMQ scores was predicted by practice time. Conclusions: The study showed a high percentage of teachers experiencing stress, and the data supported the reliability and validity of the brief online mindfulness-enhanced course designed to reduce stress and regulate emotion for frontline teachers.

Development and validation of children's mind wandering scales.

Introduction: Mind wandering is generally considered an endogenous mental state that arises spontaneously, which is one of the most common experiences of consciousness and typically occurs at a significant cost to mental health and behavioral performance. Previous studies have shown that mind wandering appears to be a stable trait and can be assessed reliably in adults. Surprisingly little, however, is known about how to measure the frequency of mind wandering in children, given that children can accurately introspect their experiences. The present studies aimed to develop the Frequency of Children's Mind Wandering Scale (CMWS-F) and the Context of Children's Mind Wandering Scale (CMWS-C) to assess the frequency of mind wandering and contexts in which mind wandering occurs for children aged 8 to 11 years. Methods: The exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were used to develop the CMWS-F and CMWS-C. To further assess the validity of the scales, we compared the scores in CMWS-F/CMWS-C and the frequencies of probe-caught mind wandering in the typical tasks. Results: In study 1a, the EFA (n = 292) and CFA (n = 346) showed that attentional failure and spontaneous thinking were the two main dimensions of CMWS-F. In study 1b, contexts about mind wandering in children could be divided into high-demand and low-demand contexts using EFA (n = 258) and CFA (n = 347). Study 2 showed moderate positive correlations between the frequencies of probe-caught mind wandering in the tasks and the scores in the scales. Discussion: The results showed that scores on the two scales could predict the performance on the experimental tasks and further demonstrated empirical validity of the CMWS-F and CMWS-C scales. Taken together, the results of the current studies provided preliminary evidence for the validity and reliability of CMWS-F and CMWS-C in children, which can be used as a reference to balance its downsides and productive aspects of mind wandering.

Rheological Impact of Particle Size Gradation on GAP Propellant Slurries.

Over the years, widespread interest has been placed on rheological properties to reflect the processability of propellant slurries. Particle gradation technology plays an essential role in the improvement of the processability of propellant slurries. In this article, rheological properties of glycidyl azide polymer (GAP) propellant slurries were measured by dynamic rheological measurements with a rheometer. Submicron-sized (d 50 = 0.221 µm) and micron-sized (d 50 = 33.02 µm) CL-20 particles and ultrafine (d 50 = 2.40 µm) and micron-sized (d 50 = 341.69 µm) AP particles were utilized to investigate the influence of the addition of CL-20 and particle size gradation on rheological properties. The test results demonstrate that the LVE region remains almost invariable while the yield transition process is delayed when the relative content of submicron-sized CL-20 increases from 10 to 20%. The values of G', G″, and |η*| increase with increasing submicron-sized CL-20. Despite this, the value of |η*| can be effectively reduced to about the same value as the slurries with bimodal AP by the size gradation of CL-20. In addition, particle porosity appears to be a suitable parameter to predict trends concerning the rheological properties of the GAP propellant slurries.

Microbial Responses to Various Types of Chemical Regents during On-Line Cleaning of UF Membranes.

Ultrafiltration is widely used to treat various environmental waters, and on-line membrane cleaning with various chemical reagents is frequently employed to sustain the filtration flux. However, the residue of cleaning agents in the ultrafiltration system is unavoidable, which may affect microbiological properties and biofilm formation during the next-round filtration. By investigating the changes in microbial characteristics, and their biofouling behaviors after exposure to HCl, NaOH, NaClO, citric acid (CA), and sodium dodecyl sulfonate (SDS), this study fills a knowledge gap in microbial responses to various types of chemical cleaning agents in an ultrafiltration system. The result shows that HCl, NaOH, and NaClO affect the bacterial properties and subsequent attachment on the membrane surface, while CA and SDS have no obvious influence on microorganisms. Specifically, HCl, NaOH, and NaClO reduce the hydrophobicity and mean size of suspended microorganisms, increase the extracellular polymeric substances (EPS) release, and trigger intracellular reactive oxygen species (ROS) generation, resulting in the death of a large quantity of microorganisms. Due to the self-protecting strategy, plenty of living cells aggregate on the membrane surface and form a cake layer with a stratified structure, causing more severe membrane biofouling.

Interfacial Covalent Bonding Endowing Ti3 C2 -Sb2 S3 Composites High Sodium Storage Performance.

Antimony sulfide is attracting enormous attention due to its remarkable theoretical capacity as anode for sodium-ion batteries (SIBs). However, it still suffers from poor structural stability and sluggish reaction kinetics. Constructing covalent chemical linkage to anchor antimony sulfide on two-dimension conductive materials is an effective strategy to conquer the challenges. Herein, Ti3 C2 -Sb2 S3 composites are successfully achieved with monodispersed Sb2S3 uniformly pinned on the surface of Ti3 C2 Tx MXene through covalent bonding of Ti-O-Sb and S-Ti. Ti3 C2 Tx MXene serves as both charge storage contributor and flexible conductive buffer to sustain the structural integrity of the electrode. Systematic analysis indicates that construction of efficient interfacial chemical linkage could bridge the physical gap between Sb2S3 nanoparticles and Ti3 C2 Tx MXene, thus promoting the interfacial charge transfer efficiency. Furthermore, the interfacial covalent bonding could also effectively confine Sb2S3 nanoparticles and the corresponding reduced products on the surface of Ti3 C2 Tx MXene. Benefited from the unique structure, Ti3 C2 -Sb2 S3 anode delivers a high reversible capacity of 475 mAh g-1 at 0.2 A g-1 after 300 cycles, even retaining 410 mAh g-1 at 1.0 A g-1 after 500 cycles. This strategy is expected to shed more light on interfacial chemical linkage towards rational design of advanced materials for SIBs.

Effects of a Four-Day Mindfulness Intervention on Teachers' Stress and Affect: A Pilot Study in Eastern China.

Stress is becoming increasingly prevalent among teacher groups, and this is problematic for education. Mindfulness training (MT) is a well-supported way to help various populations cope with and reduce stress. In this study, a 4-day intensive MT program that aimed to increase teachers' emotional health was developed and implemented into the existing post-service education for teachers in eastern China. A total of 161 teachers voluntarily enrolled in the course and were assigned to either the mindfulness group or the waitlist group. Participants completed measures of mindfulness, positive affect, negative affect, and perceived stress before and after the program. The results showed that MT had statistically significant positive effects on mindfulness, negative affect, and stress. The present findings indicate that a 4-day intensive MT program is a promising way to decrease teachers' stress and improve their emotional health. The practical meaning of the short-term intensive MT program for teachers is discussed. It is easier for teachers to enroll such a short-term training program, as it may have higher acceptance and feasibility than an 8-week training program in some areas. Clinical Trial Registration: www.ClinicalTrials.gov, identifier ChiCTR2000029653.

Low-cost 3D porous sea-hedgehog-like NiCo2O4/C as anode for Li-ion battery.

Carbon is effective additive to improve cyclic performances of transition metal oxides for lithium ion battery, while common graphene or carbon nanotube is expensive. In this study, waste of rice husk is used to prepare low cost carbon. A composite of NiCo2O4/carbon is synthesized via hydrothermal method plus calcination. At hydrothermal time of 6 h, the material displays 3-D sea hedgehog-like structure with radial corn cob-shaped nanorod. The NiCo2O4/carbon presents better rate performances, coulombic efficiency and cyclic stability than pristine NiCo2O4, showing stable capacity of 1018 mAhg-1 (52.6% higher than NiCo2O4) after 100 cycles at 0.1 Ag-1. For long-term cycling during 500 cycles at 0.5 Ag-1, the composite anode exhibits a reversible capacity of ∼880 mAhg-1, with high retention of 92.2%. The capacity is still retained ∼715 mAhg-1 even after 1000 cycles at 1 Ag-1.

Characterization and Properties of F2602/GAP/CL-20 Energetic Fibers with High Energy and Low Sensitivity Prepared by the Electrospinning Method.

In this work, three samples of fluoroelastomers/glycidyl azide polymer/hexanitrohexaazaisowurtzitane (F2602/GAP/CL-20) energetic fibers with F2602/GAP:CL-20 ratios of 1:9, 2:8, and 3:7 were prepared by the electrospinning method. The morphologies and structures of the samples were characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The results revealed that F2602/GAP/CL-20 energetic fibers showed a three-dimensional network structure, and four elements C, N, O, and F were observed on the surface. The surface of the fiber F2602/GAP:CL-20 = 1:9 was uniform and smooth. Differential scanning calorimetry was used to analyze the thermal decomposition properties of the samples. The apparent activation energy of the F2602/GAP/CL-20 energetic fiber was 399.86 kJ/mol, indicating high thermal stability. TG-MS analysis results show that the thermal decomposition products of F2602/GAP/CL-20 are mainly C2H6, H2O, N2, and CO2. The results of the energy performance evaluation showed that the standard specific impulse (I sp) of F2602/GAP/CL-20 was 2668.1 N s kg-1, which was remarkably higher than I sp of the state-of-the-art AP/HTPB/Al propellant. In addition, compared to that of CL-20, the friction sensitivity of one F2602/GAP/CL-20 sample decreased by 38%, and the sensitivities of the other two F2602/GAP/CL-20 samples were even less than zero. F2602/GAP/CL-20 fibers also exhibited a higher feature height. Therefore, these kinds of CL-20-based fibers are high-energy materials with very low sensitivity.

Internet Gaming Disorder Increases Mind-Wandering in Young Adults.

As a primary symptom defining Internet gaming disorder (IGD), preoccupation indicates a mind state in which gamers think about a gaming activity so much that other things appear less important and/or interesting to them. Previous studies have examined the negative impacts of IGD on both cognitive and affective functions, yet no study has investigated the influence of IGD on daily mind state changes that interfere with ongoing tasks. The current study hypothesized that more IGD symptoms lead to a higher frequency of mind state shift in terms of mind-wandering. As social anxiety is related to both IGD and mind-wandering, we further hypothesized that social anxiety would partially contribute to the relationship. Survey data were collected from 632 young adults who were divided into two groups based on whether they reported playing games or not. In the player group, the number of IGD symptoms present was positively related to mind-wandering (r = 0.269, p < 0.001) and social anxiety (r = 0.235, p < 0.001), with the latter two showing a positive correlation in both players (r = 0.37, p < 0.001) and non-players (r = 0.57, p < 0.001). A mediation analysis for the players showed a partial mediation effect of social anxiety on the relationship between IGD and mind-wandering (mediation effect: PM = 0.292, p < 0.001), and the model was replicated in an independent sample. This study suggests that excessive gaming behavior may increase mind-wandering and a shift towards such a non-productive mind state could exert long-term detrimental effects in adolescents and young adults.

Production of activated carbons from four wastes via one-step activation and their applications in Pb2+ adsorption: Insight of ash content.

Natural biomass is a renewable source for precursors of porous carbon. Four agriculture wastes of corn cob (CC), wheat bran (WB), rice husk (RH), and soybean shell (SS) were applied to produce activated carbons (ACs) via one-step activation by sodium hydroxide. The effects of ash contents and NaOH dosage ratio (1-5) on surface area for ACs were investigated. Owing to ash etching, the high ash precursor (like RH) exhibited less alkali consumption and larger surface area than low ash one (like CC). All four ACs expressed developed pore structure and outstanding surface area of ∼2500 m2g-1. During adsorption of lead ions in simulated wastewater, RH-based AC revealed superior capture capacity of 492 ± 15 mgg-1. One-step activation had the potential to deliver savings around 1/3 of energy consumption, enabling the cost performance of high ash RH-based AC reaching 194 ± 12 g Pb2+$-1, 76% larger than low ash CC-based AC. High ash biomass is a promising candidate to obtain eco-friendly carbon products.

Nanometer Ammonium Perchlorate and Ammonium Nitrate Prepared with 2D Network Structure via Rapid Freezing Technology.

Nanometer (nano) ammonium perchlorate (AP) and ammonium nitrate (AN) were prepared with 2D network structures by the ultra-low temperature spray method. Scanning electron microscopy (SEM), X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis/infrared spectrometry (TG-IR) were employed to probe the micron structure, crystal phase, and thermal decomposition of nano AP and nano AN. SEM images revealed that the sizes of nano AP and AN were in the nanometer scale (<100 nm) in one dimension. XRD patterns showed that the crystal phases of nano AP and AN were in accordance with those of raw AP and raw AN, respectively. DSC traces indicated that the thermal decomposition process of AP depended on its particle size, while the thermolysis of AN was independent of the particle size of AN. TG-IR analyses illustrated that the decomposition products of nano AP were NO2, N2O, HCl and H2O, with a small amount of NOCl, and the main decomposition products of nano AN were N2O and H2O, with a small amount of NH3. The results of mechanical sensitivity tests indicated that nano AP was more sensitive than raw AP and both nano AN and raw AN were very insensitive to impact and friction stimuli.

Electrospinning Preparation of NC/GAP/Submicron-HNS Energetic Composite Fiber and its Properties.

In this work, novel three-dimensional nitrocellulose/glycidyl azide polymer/submicron-2,2', 4,4', 6,6'-hexanitro-stilbene (NC/GAP/submicron-HNS) composite fibers were prepared by the electrospinning method. As-prepared NC/GAP/submicron-HNS fibers were continuous and possessed a large specific surface area. The structure of fibers was characterized by energy-dispersive X-ray, X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy (IR). The results showed that HNS submicron particles were uniformly loaded on the surface of NC/GAP fibers and incorporated with it. Thermal analyses were performed. Such NC/GAP/submicron-HNS fibers showed a low activation energy of 204 kJ·mol-1 and large rate constant of 1.74 s-1, indicating high reactivity and fast reaction rate. The result of TG-IR analysis revealed that the main decomposition products of NC/GAP/submicron-HNS were CO2, CO, H2O, N2O, few NO, and fragments such as -CH2O- and -CH-, which were low-signature gases. An evaluation on the energy performance disclosed that the standard specific impulse (I sp) of NC/GAP/submicron-HNS fibers was 2032 N·s·kg-1, which was higher than 2014 N·s·kg-1 of NC/GAP. This meant the addition of HNS submicron particles to the NC/GAP fiber was favorable to the improvement of energy performance. Additionally, introduction of submicron-HNS made the energetic fibers becoming very insensitive to impact action. It was expected that as-prepared NC/GAP/submicron-HNS membranes were promising materials applied for solid rocket propellant.

Thermal Behavior and Decomposition Mechanism of Ammonium Perchlorate and Ammonium Nitrate in the Presence of Nanometer Triaminoguanidine Nitrate.

Nanometer triaminoguanidine nitrate (TAGN) with mean size of 218.7 nm was fabricated, and its structures were characterized by scanning electron microscopy, X-ray diffraction, IR, and X-ray photoelectron spectroscopy analyses. As an energetic accelerator for thermal decomposition of ammonium perchlorate (AP) and ammonium nitrate (AN), 10% nano TAGN blended with AP and AN, and samples "[90% AP + 10% (nano TAGN)]" and "[90% AN + 10% (nano TAGN)]" were obtained, respectively. Differential scanning calorimetry (DSC) analyses were employed to investigate the decomposition kinetics and thermodynamics of the samples. The results indicated that [90% AP + 10% (nano TAGN)] presented a higher activation energy (152.34 kJ mol-1) than pure AP (117.21 kJ mol-1) and [90% AN + 10% (nano TAGN)] possessed a lower activation energy (147.51 kJ mol-1) than pure AN (161.40 kJ mol-1). All activation free energies (ΔG ≠) were positive values. This means that activation of the molecules was not a spontaneous process. The decomposition peak temperature of AP decreased from 478.5 °C (for pure AP) to 287.2 °C (for [90% AP + 10% (nano TAGN)]). The decomposition peak of AN also advanced via doping with nano TAGN. Using DSC-IR analysis, the decomposition products of nano TAGN, pure AP, [90% AP + 10% (nano TAGN)], pure AN, and [90% AN + 10% (nano TAGN)] were investigated, and their decomposition mechanisms were proposed. The key factors, i.e., the formation of hydrazine in the decomposition of nano TAGN, were speculated, which substantially promoted the consumption of HNO3, HClO4, and their decomposition products in kinetics. Additionally, the energy performances of AP- and AN-based propellants doping with TAGN were evaluated. It is disclosed that the introduction of TAGN would not result in improvement in the energy performance of propellants, but due to its energetic property and high hydrogen content, proper introduction of TAGN will not reduce the energy performance of propellants in a large degree compared with the introduction of inert catalysts.

An Electrospun Preparation of the NC/GAP/Nano-LLM-105 Nanofiber and Its Properties.

In this work, an energetic composite fiber, in which 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) nanoparticles intimately incorporated with a nitrocellulose/glycidyl azide polymer (NC/GAP) fiber, was prepared by the electrospinning method. The morphology and structure of the nanofiber was characterized by scanning electron microscopy (SEM), energy dispersive X-Ray (EDX), fourier transform infrared spectroscopy (IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET). The nanofibers possessed a three-dimensional (3D) net structure and a large specific surface area. Thermal analysis, energetic performance, and sensitivities were investigated, and they were compared with NC/GAP and LLM-105 nanoparticles. The NC/GAP/nano-LLM-105 nanofibers show higher decomposition rates and lower decomposition temperatures. The NC/GAP/nano-LLM-105 decomposed to CO2, CO, H2O, N2O, and a few NO, -CH2O-, and -CH- fragments, in the thermal-infrared spectrometry online (TG-IR) measurement. The NC/GAP/nano-LLM-105 nanofibers demonstrated a higher standard specific impulse (Isp), a higher combustion chamber temperature (Tc), and a higher specialty height (H50). The introduction of nano-LLM-105 in the NC/GAP matrix results in an improvement in energetic performance and safety.

Mechanochemical fabrication and properties of CL-20/RDX nano co/mixed crystals.

By milling 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) together, a nano CL-20/RDX co/mixed crystal explosive with a mean particle size of 141.6 nm is prepared from the raw materials, and the co/mixed crystals are characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) and thermal-infrared spectrometry online (DSC-IR) technology; furthermore, the impact, friction and thermal sensitivity of the samples are tested. The results show that after milling, the morphology of the co/mixed crystal explosive is near-spherical, and the particle size reveals a normal distribution. The milled sample showed the same molecular structure and surface elements as the raw materials, but the XRD test shows that CL-20/RDX has a new crystal phase and the Raman and IR spectra gave a supplementary confirmation for the existence of a cocrystal phase in the milled sample. The activation energy of the thermal decomposition of CL-20/RDX is 206.49 kJ mol-1 higher than that of raw RDX. DSC-IR analysis showed that the thermolysis of CL-20/RDX produces a large amount of CO2 and N2O and a small amount of H2O, NO2 and NO. The mechanical sensitivity of CL-20/RDX is very low. In impact sensitivity tests with a 5 kg hammer, the special height (H 50) is 51.43 cm, which is higher than the values of 36.43 cm for raw CL-20 and 9.78 cm for raw RDX. In the friction sensitivity tests, the explosion probability (P) is 56%; however, the thermal sensitivity of CL-20/RDX is higher than that of the raw materials, with its 5 s burst point being only 243.51 °C.

Synthesis, thermolysis, and sensitivities of HMX/NC energetic nanocomposites.

1,3,5,7-Tetranittro-1,3,5,7-tetrazocane/nitrocellulose (HMX/NC) nanocomposites were successfully synthesized by an improved sol-gel-supercritical method. NC nanoparticles with a size of ∼30nm were cross-linked to form a network structure, and HMX nanoparticles were imbedded in the nano-NC matrix. The key factors, i.e., the selection of catalyst and solvent, were probed. No phase transformation of the HMX occurred before or after fabrication, and the molecular structures of the HMX and NC did not change. Thermal analyses were performed, and the kinetic and thermodynamic parameters, such as activation energy (EK), per-exponent factor (lnAK), rate constant (k), activation heat (ΔH(≠)), activation free energy (ΔG(≠)), activation entropy (ΔS(≠)), critical temperature of thermal explosion (Tb), and critical heating rate of thermal explosion (dT/dt)Tb, were calculated. The results indicate that HMX/NC presented a much lower activation energy (165.03kJ/mol) than raw HMX (282.5kJ/mol) or raw NC (175.51kJ/mol). The chemical potential (ΔG(≠)) for the thermal decomposition of HMX/NC has a positive value, which means that the activation of the molecules would not proceed spontaneously. The significantly lower ΔH(≠) value of HMX/NC, which represents the heat needed to be absorbed by an explosive molecule to change it from its initial state to an activated state, implies that the molecules of HMX/NC are much easier to be activated than those of raw HMX. Similarly, the HMX/NC presented a much lower Tb (168.2°C) than raw HMX (283.2°C). From the results of the sensitivity tests, the impact and friction sensitivities of HMX/NC were significantly decreased compared with those of raw HMX, but the thermal sensitivity was distinctly higher. The activation of the particles under external stimulation was simulated, and the mechanism was found to be crucial. Combining the thermodynamic parameters, the mechanism as determined from the results of the sensitivity tests was discussed in detail.

Children with positive attitudes towards mind-wandering provide invalid subjective reports of mind-wandering during an experimental task.

This study investigated mind-wandering (MW) in children during a laboratory task, and explored the influence of children's attitudes towards MW on the accuracy of their subjective reports. Children's MW experiences were probed during the adapted Sustained-Attention-to-Response-Task (SART), and their attitudes was measured by a questionnaire, according to which children were divided into positive or negative group. Results showed that (1) MW in children was basically identical to MW in adults which was associated with poor performance, increased behavioural variability, and a prospective bias; (2) reliable correlations between behavioural correlates and MW frequency were observed in negative group, but not in positive group; and (3) positive group reported more MW than negative group, while no behavioural correlate was significantly different between the two groups. We concluded that (1) overall, children could accurately introspect their MW experiences during SART; and (2) children with positive attitudes provided invalid subjective reports of MW.