Tetramethylethylenediamine Research Articles

Stress, Coping, and Transcendental Meditation: A Proto-Theoretical Model and Pilot Study of Indigenous Peruvian Students in Home Isolation During the COVID-19 Pandemic

ABSTRACT Adverse impacts on children in home isolation during the COVID-19 pandemic have been documented. These impacts include increased loneliness, anxiety, depression, posttraumatic disorder, and heightened risk of psychiatric illness. The present study introduces a proto-theoretical model of stress, psychophysiology, and coping to explain this phenomenon. A focus of the research is on evaluating the model by considering the experience of Aymara and Quechua children in home isolation at a primary and secondary school in Puno, Peru, and the potential role of Transcendental Meditation to enhance the health, coping, and academic achievement of this unique group of school children in such a remote, indigenous Latin American setting. We asked 54 children at Institución Educativa Privada Prescott to quantitatively rate their experience of Transcendental Meditation while in home isolation in terms of physical, cognitive, and emotional health, academic achievement, coping, learning, anxiety, depression, and optimism. Ninety-eight percent of students (53/54) reported that the practice had beneficially affected their health and academic achievement. On a 1–10 scale, average ratings of the impact of Transcendental Meditation on physical health were 7.55, on cognitive health were 7, on emotional health were 7.48, and on academic achievement were 7.85. Scores on coping, learning, anxiety, depression, and optimism were of a similar order of magnitude. Implications for public and health safety in Peru are discussed.

Your brain on art, nature, and meditation: a pilot neuroimaging study.

Exposure to art, nature, or meditation, all transcending human experiences, has beneficial effects on health and wellbeing. Focusing inward or watching art and nature videos elicits positive emotions that can help heal stress-related conditions. In a pilot functional magnetic resonance (fMRI) study, we explored the effect of watching digital art or nature videos compared to contemplating the universal connectedness (also known as transcendental meditation). The instructions were to meditate on the connection to a Universal Soul linked to a sense of expansion and universal connectedness ("one with everything"), which was prompted by a video of the galactic nebula that also controlled for the visual stimuli of the two other conditions. Nine healthy adults (mean age = 29; range = 19-42; 5 women) underwent a block design fMRI scan using a Siemens 3T Prisma scanner. The blocks included (1) nature videos, (2) AI-generated digital art ("machine hallucinations" by Refik Anadol), and (3) videos of NASA Webb-produced images of galactic nebulas. Brain oxygen-level dependent (BOLD) images were processed using FSL Version 6.0 and a general linear model (GLM) tested the contrasts between art, nature, and meditation blocks, using a cluster-corrected p-value of 0.05. Compared to rest, meditation led to BOLD increases in bilateral lateral occipital and fusiform gyri, as well as right postcentral gyrus and hippocampus. Compared to viewing AI-generated digital art, increased BOLD responses during meditation were observed in left parietal and central operculum, and right pre- and postcentral gyri, and compared to nature, in the left parietal operculum, bilateral postcentral and supramarginal gyri, and bilateral lateral occipital cortices. Meditation compared to rest showed brain activation in regions associated with object, sensory, and memory processing. Meditation compared to nature videos led to activity in bilateral sensory and object processing areas, as well as a left sensory integration region (error monitoring), while meditation compared to art showed activity in left sensory integration and right sensorimotor regions. Further studies are needed to delineate the distinct neural signature and therapeutic effects of inner contemplation using human connection to art, nature, or meditative transcendent practices, in the brain and its potential in clinical applications.

Synthesis, crystal structure, characterization and antimicrobial activities of ternary chiral mononuclear Schiff base copper(II) complexes.

[CuL1-4(tmen)] is a sequence of four ternary mononuclear Schiff base copper(II) complexes that are derived from L-valine, suitable 5'-substituted-2'-hydroxyacetophenones (where the substituents are -Cl for L1, -Me for L2, -OMe for L3, and -H for L4), and tmen (where tmen-N,N,N',N' tetramethyl ethylenediamine). Without isolating the Schiff base ligand or producing any other intermediate products, all of the complexes were synthesised. These compounds were identified using elemental analysis, molar conductance, UV-Vis, FTIR, EPR, VSM-RT, and CD spectra. Single crystal XRD was used to characterise the structure of Complex 1. The crystalline structure exhibits a distorted square pyramidal shape wherein the Schiff base forms an axial bond with the Cu(II) ion through the ONO-donor, while the chelating ligand tmen exhibits both an equatorial and an axial mode of binding through the NN-donor atoms. Hydrogen bonding and non-covalent CH(methyl)π(phenyl) interaction are two intriguing aspects of compound 1's packing diagram. By calculating the minimum inhibitory concentration (MIC) against harmful bacteria, the synthesised complexes' antimicrobial activity was assessed. According to the bioactivity experiments, the microorganisms employed in this investigation were susceptible to the antibacterial and antifungal properties of copper(II) complexes 1-4. According to the bioactivity experiments, the microorganisms employed in this investigation were susceptible to the antibacterial and antifungal properties of copper(II) complexes 1-4.

Randomized Trial: A Pilot Study Investigating the Effects of Transcendental Meditation and Yoga Through Retinal Microcirculation in Cardiac Rehabilitation

Background/Objectives: Cardiovascular diseases are a leading cause of death, and psychosocial stress is considered a contributing factor to these issues. With the rising number of heart surgeries, proper rehabilitation post-surgery is essential. Previous studies have demonstrated the positive impact of yoga and transcendental meditation on the cardiovascular system. This pilot study aimed to investigate the effects of yoga and transcendental meditation on retinal microcirculation in cardiac patients before (admission), after (discharge), and following (3 weeks after discharge) rehabilitation. Methods: This study examined changes in retinal microcirculation in three rehabilitation groups of patients after heart surgery. The control group received standard exercise therapy, while the meditation group incorporated 20 min of meditation, and the yoga group incorporated 20 min of yoga practice, twice per day for the duration of four weeks of rehabilitation. Retinal images were captured using a non-mydriatic digital retinal camera (Canon CR-2, Canon Medical Systems Europe B.V., Netherlands), and the microcirculation parameters central retinal artery equivalent, central retinal vein equivalent, and artery-to-vein ratio were analyzed using MONA REVA software ((version 2.1.1), VITO, Mol, Belgium). Repeated measures ANOVA was performed to evaluate differences between the three groups in the course of rehabilitation. Results: None of the parameters revealed significant differences in retinal microcirculation between the three rehabilitation groups. Conclusions: The study evaluating changes in retinal microcirculation, as an indicator of central circulation in cardiac patients undergoing rehabilitation, did not observe any significant changes. As yoga and meditation are underestimated approaches in cardiac rehabilitation, this pilot study acts as a basis for providing preliminary information for future studies to encourage the research community to fill the gap in this area.

Cost-effectiveness of Transcendental Meditation (TM) for treating Post-Traumatic Stress Disorder (PTSD).

A recent trial found that Transcendental Meditation (TM) was an effective non-trauma focused treatment for veterans with Post-Traumatic Stress Disorder (PTSD). The objective of this analysis was to examine the cost-effectiveness of TM for PTSD based on the trial results. Between 2013-2017, 203 veterans with PTSD were randomized to either TM, Prolonged Exposure (PE), or to a PTSD health education (HE) control. Each group received 12 treatment sessions over 12 weeks. Results indicated that TM was non-inferior to PE for improving PTSD outcomes and both TM and PE were superior to HE, as hypothesized. The proportion of participants with a clinically significant improvement on the CAPS (≥10 point reduction) were TM = 61%, PE = 42%, and HE = 32%. A Markov model was developed to estimate the cost-effectiveness of TM, using the trial effectiveness data. Intervention costs, health care costs, and health utility values associated with response and non-response were derived from scientific literature. Costs were viewed from an organizational perspective and a 5-year time horizon (20 3-month cycles). One-way and probabilistic sensitivity analyses were conducted. TM was the dominant treatment strategy over both PE and HE in the cost-effectiveness analysis. TM cost an estimated $1504/12 sessions while PE and HE cost $2,822 and $492, respectively. The higher health care costs associated with non-response to therapy offset intervention cost differences. Findings were robust to variability. In summary, using data from a recent RCT, TM was found to both improve health outcomes and reduce total costs in this analysis. Based on these results, further effectiveness trials and wider adoption of TM should be considered.

What are the effects of transcendental meditation for people who are at high risk of, or already have, cardiovascular disease (CVD)?

What are the effects of transcendental meditation for people who are at high risk of, or already have, cardiovascular disease (CVD)?

Evaluation of adsorption characteristic of GG-g-polyacrylic acid P(AA)/CoFe2O4 for the metamorfin hydrochloride (MF) and diclofenac sodium(DCF)

ABSTRACT The removal of contaminants from the water system is so significant for the better human life. Adsorption method is proven to be best method for the decontamination of waste water. Adsorbent based on biohydrogel is widely used for this purpose so biooriginated adsorbent named GG-g- P(AA)/CoFe2O4 (30 mg)-GGAACF-3 was synthesised and utilised for the combine removal of metformin hydrochloride (MF) and diclofenac sodium (DCF). GG-g- P(AA)/CoFe2O4 (30 mg)-GGAACF-3 prepared using free radical initiator ammonium persulphate(APS), cross-linked using crosslinking agent N, N’- methylenebisacrylamide (MBA) and accelerator using tetramethyl ethylenediamine (TEMED). The GGAACF-3 exhibited high removal efficiency for DCF than MF. The highest removal efficiency for DCF and MF found to 82.17% and 69.26% at adsorbent dose 40 mg, neutral pH, room temperature (20°C) and contact time 24 h, respectively. Adsorption of both drugs followed the Langmuir adsorption isotherm and Pseudo- 2nd-order model kinetic model which indicated about homogeneous adsorption of both drugs on the surface of GGAACF-3 and chemisorption, respectively. The maximum adsorption capacity (qe) for MF and DCF determined to 123.60 mg/g and 120.7729 mg/g, respectively.

WORKPLACE SPIRITUALITY: SHAPING THE FUTURE OF THE MODERN ORGANISATIONS

Creating and maintaining a healthy organization has become a significant challenge for leaders in today’s volatile and competitive business landscape. A crucial component of a healthy organization is the mental well-being of employees. In particular, teaching is a highly stressful profession that exposes educators to the risk of burnout. To mitigate this, techniques that engage higher mental functions—such as transcendental meditation and prayer—have been incorporated into stress and burnout prevention programs. Spirituality in education plays a key role in enhancing the quality of teaching and learning, though it is influenced by various personal, social, religious, and cultural factors. This study explores the relationship between workplace spirituality, meditation, and teacher performance. It evaluates the impact of wellness and spirituality on teachers' work performance. Data were collected from 375 teachers in the Hubli-Dharwad region, revealing that spirituality has a positive influence on work performance. A workplace that supports both wellness and spirituality fosters a more conducive environment for effective work.

Hidden Boron Catalysis: A Cautionary Tale on TMEDA Inhibition.

Hidden boron catalysis plagues catalyzed hydroboration reactions, with the "catalyst" acting to mediate the decomposition of HBpin/HBcat to BH3 which is the actual (hidden) catalyst. N,N,N',N'-Tetramethylethylenediamine (TMEDA) has been used to identify hidden boron catalysis through trapping/inhibition. Kinetic analyses showed that TMEDA inhibition is only applicable below 60 °C and that other amine traps are likewise ineffective. Awareness of this temperature limitation reveals widespread hidden catalysis in previous methods and should limit future false negative tests.

Sodium Alkyl(trimethylsilyl)amides: Substituent- and Solvent-dependent Solution Structures and Reactivities.

The preparation of sodium isopropyl(trimethylsilyl)amide (NaPTA), sodium (1-phenylethyl)(trimethylsilyl)amide (NaPETA), sodium tert-butyl(trimethylsilyl)amide (NaBTA), and isotopologues [15N]NaPTA and [15N]NaBTA are described. Solution structural studies using a combination of 29Si NMR spectroscopy, the Method of Continuous Variations, and density functional theory computations provided insights into aggregation and solvation in a range of solvents including toluene, N,N-dimethylethylamine, triethylamine, MTBE, THF, 1,2-dimethoxyethane (DME), diglyme, N,N,N',N'-tetramethylethylenediamine (TMEDA), N,N,N',N'-tetramethylcyclohexanediamine (TMCDA), N,N,N',N″,N″-pentamethyldiethylenetriamine (PMDTA). 12-crown-4, 15-crown-5, and 18-crown-6 revealed solvent- and substituent-dependent dimer-monomer mixtures with affiliated solvation numbers. Complexation of the three crown ethers documented both crown and substituent dependencies. Qualitative studies of reactivity showed a variety of reactions of NaPETA. Aminolysis of methyl benzoate with dialkylamines mediated by NaPTA afforded high yields of benzamides. Quantitative rate studies of aminolysis of methyl benzoate by NaPTA revealed a 47,000-fold range of rates. Detailed rate studies in toluene and THF showed dimer-based mechanisms. The role of primary- and secondary-shell solvation by THF is discussed, including nuances of methods used to separate the two contributions. PMDTA-solvated NaPTA monomer reacts as a monomer whereas bis-diglyme solvated monomer reacts as a dimer. Rate studies exploring the structure-reactivity correlations of the three crown ethers show mono- and bis-crown-based pathways in which 15-crown-5─the crown ether often said to be of choice for sodium─was decidedly inferior as an accelerant.

Optimization of parameters for the preparation of AlN powder/thin films by tris(N,N,N’,N’-tetramethylethylenediamine) al(III) chloride precursor

The single source precursor tris(N,N,N’,N’-tetramethylethylenediamine)Al(III)Cl3 has been synthesized by the reaction of N,N,N’,N’-tetramethylethylenediamine (TMEDA) with AlCl3 in 3:1 molar ratio in ethanol. The precursor is stable for long periods of time and cleanly generated aluminum nitride upon pyrolysis. The pyrolysis process was optimized by varying parameters such as temperature, pressure, and the flow rate of gases (N2 and Ar). Thin films of AlN were prepared by spin coating the precursor onto Si(100) and quartz substrates followed by pyrolysis under optimized CVD conditions obtained from bulk pyrolysis. Pyrolyzed powders and films were characterized with a variety of techniques. X-ray diffraction (XRD) showed 8.5 nm grain size with a dominant 220 orientation. UV-Vis spectroscopy indicated a band gap for the AlN films of ∼5.7 eV, which is close to bulk AlN (6.1 eV). FESEM showed a smooth and homogeneous film surface and EDAX showed a 1.4:1 ratio of Al:N, respectively.

Self-Sacrificed Additive in Preparing PbI2 Film Enables the Oriented Growth of Perovskite Crystals for Improved Solar Cell Performance.

Due to the limitation of the diffusion kinetics of organic amine salts on the PbI2 layer in the two-step method, prepared perovskite particles are small in size, have many defects, and are randomly oriented, and the cell efficiency and stability are difficult to guarantee due to PbI2 residues. Here, we added a volatile additive, N,N,N',N'-tetramethylethylenediamine (TMEDA), to the PbI2 precursor solution and formed preaggregated atomic clusters with PbI2 through TMEDA, which reduced the Gibbs free energy of nucleation to obtain a porous PbI2 layer, and finally obtained a perovskite film with large particles, few defects, ideal crystal plane orientation, and no additive residues. The results show that the photoelectric conversion efficiency of the optimized device is increased by 1.68% (from 21.68% to 23.36%), and the unpackaged optimized device still maintains the maximum efficiency of 77% after being placed in the air for 1200 h. This study provides an effective way to fabricate efficient and stable perovskite solar cells by promoting the nucleation-induced crystallization orientation by volatile additives.

Spirituality and Transcendental meditation practitioners’ experiences in South Africa and Ghana

ABSTRACT Spirituality involves being in harmony with the cosmos or nature and a willingness to engage in good works for the sake of mankind; for instance, love for one another, care for the environment, and the production and protection of the common good for society. Spirituality could also be defined as the connectedness with nature or the cosmos, seeing beyond the circumstances of one’s limitation and the suffering one encounters (transcendence) and understanding one purpose and meaning of one existence. In an African context, spirituality is experienced by many people as being in touch with one’s spirit which is an indication of integration of the body with the spirit and without this spiritual aspect of the essence of oneself, it becomes natural to see and feel problem. When one is permanently established on the platform of the Transcendental Being, life is lived in eternal freedom and enjoyment of blissfulness throughout the day. In this vein, the self silently witnesses daily activity. This is the essence of TM practice where practitioners experience spiritual upliftment. Though much research has been done on TM globally, the spiritual lived experiences of the practitioners have not been adequately explored, especially in South Africa and Ghana. Therefore, the study sought to explore the spiritual lived experiences of TM practitioners in South Africa and Ghana. The study adopted the constructivist paradigm through the lens of phenomenology. In all, 28 participants took part in the study − 14 participants from South Africa and another 14 from Ghana. Open-ended questionnaires and semi-structured interviews were used to collect data for the study. Husserl’s transcendental phenomenological data analysis was used to analyze and synthesize the descriptions of the spiritual lived experiences of the TM practitioners. The results suggest that TM act as a catalyst for the spiritual growth of the participants from both countries and that they experienced spiritual upliftment with the practice of TM. However, two participants both females were of the view that TM has nothing to do with their spirituality. It is the recommendation of this study that people who seek a spiritual path to discover their purpose and meaning in life explore this technique although there are other paths toward spiritual enlightenment. For instance, Christian’s contemplations player and Sufism.

Development of nanocomposite hydrogel using citrate-containing amorphous calcium phosphate and gelatin methacrylate.

Nanocomposite hydrogels are suitable in bone tissue engineering due to their resemblance with the extracellular matrix, ability to match complex geometries, and ability to provide a framework for cell attachment and proliferation. The nanocomposite hydrogel comprises organic and inorganic counterparts. Gelatin methacrylate (GELMA) is an extensively used organic biomaterial in tissue engineering due to its excellent biocompatibility, biodegradability, and bioactivity. The photo-crosslinking of GELMA presents a challenge when aiming to create thicker nanocomposite hydrogels due to opacity induced by fillers, which obstructs the penetration of ultraviolet (UV) light. Therefore, using a chemical crosslinking approach, we have developed nanocomposite GELMA hydrogel in this study by incorporating citrate-containing amorphous calcium phosphate (ACP_CIT). Ammonium persulfate (APS) and Tetramethylethylenediamine (TEMED) were deployed to crosslink the methacrylate group of GELMA. The oscillatory shear tests have confirmed that crosslinking enhances both storage (G') and loss modulus (G″) of GELMA. Subsequently, incorporation of ACP_CIT in GELMA hydrogel shows further enhancement in G' and G″ values. In vitro analysis of the developed hydrogels revealed that chemical crosslinking and incorporation of ACP_CIT do not compromise the cytocompatibility of the GELMA. Hence, for developing nanocomposite GELMA hydrogels employing APS/TEMED crosslinking emerges as a promising alternative to photo-crosslinking.

Mental Health and Meditation in a Post-Pandemic Perú: A Normative Study of Upper Primary School Children

In a post-pandemic Perú, problems associated with the mental health of children have been highlighted and effective methods of intervention have been discussed. This study sought to examine: 1) current levels of depression, anxiety, and stress in Perúvian school children; 2) how these levels compare to other children in Latin America and elsewhere; 3) whether these levels are different when covaried for school, age, gender, and grade level; and 4) whether there are any indications that depression, anxiety, or stress are lower when Perúvian school children practice Transcendental Meditation. For a group of 809 children from two schools using the DASS-21, findings indicate depression M = 6.79, anxiety M = 6.31, and stress M = 7.37. These data indicate somewhat elevated levels when compared to other pre-pandemic adolescents in Australia, Chile, China, and Malaysia, but were lower when compared to a group of similar-aged children at another school in China. Preliminary results also suggest lower levels of depression, anxiety, and stress can be observed in children who practice Transcendental Meditation as part of the school curriculum. School, age, gender, and grade level did not predict these differences, although girls had higher levels than boys, a finding consistent with other research.

Visible‐Light‐Promoted Cascade Radical Cyclization for Difluorochroman‐4‐ones via Electron Donor‐Acceptor Complexes

The research of electron donor‐acceptor complex has developed fast in the field of photochemistry. Herein, the green and efficient metal‐free visible‐light‐promoted synthesis of difluorochroman‐4‐ones has been achieved with 2‐(allyloxy)arylaldehyde and bromodifluoroacetamide, which is driven by noncovalent interactions between 2‐(allyloxy)arylaldehyde/N,N,N',N'‐tetramethylethylene diamine (TMEDA) and bromodifluoroacetamide/TMEDA. By precisely optimizing the electron donor and reaction solvent, a wide range of structurally diverse difluorochroman‐4‐ones, including aryl amide, aliphatic amide and ester groups, were obtained in up to 76% yields. This strategy offers the benefits of simple operation, good yields, high atomic economy and broad applicability, providing an essential complement to traditional approaches for the preparation of chroman‐4‐one skeletons without any transition metals, photocatalysts or oxidants.

Visible-Light-Induced Domino Perfluoroalkylation/Cyclization to Access Perfluoroalkylated Quinazolinones by an EDA Complex.

The electron donor-acceptor (EDA) complexes have been extensively studied, which formed an electronically excited state, obviating the need for an exogenous photocatalyst. Herein, we report a mild and efficient strategy for photoinduced radical domino perfluoroalkylation/cyclization using N,N,N',N'-tetramethylethane-1,2-diamine (TMEDA) as an electron donor. This protocol could be well expanded to access various polycyclic quinazolinones containing perfluoroalkyl groups, exhibiting photocatalyst-free, good functional group tolerance, and environmentally friendly features.

Dual Photoreactive Ternary Ruthenium(II) Terpyridyl Complexes: A Comparative Study on Visible-Light-Induced Single-Step Dissociation of Bidentate Ligands and Generation of Singlet Oxygen.

The versatile and tunable ligand-exchange dynamics in ruthenium(II)-polypyridyl complexes imposed by the modulation of the steric and electronic effects of the coordinated ligands provide an unlimited scope for developing phototherapeutic agents. The photorelease of a bidentate ligand from the Ru-center is better suited for potent Ru(II)-based photocytotoxic agents with two available labile sites for cross-linking with biological targets augmented with possible phototriggered 1O2 generation. Herein, we introduced a phenyl-terpyridine (ptpy) ligand in the octahedral Ru(II) core of [Ru(ptpy)(L-L)Cl]+ to induce structural distortion for the possible photorelease of electronically distinct bidentate ligands (L-L). For a systematic study, we designed four Ru(II) polypyridyl complexes: [Ru(ptpy)(L-L)Cl](PF6), ([1]-[4]), where L-L = 1,2-bis(phenylthio)ethane (SPH) [1], N,N,N',N'-tetramethylethylenediamine (TMEN) [2], N1,N2-diphenylethane-1,2-diimine (BPEDI) [3], and bis[2-(diphenylphosphino)phenyl]ether (DPE-Phos) [4]. The detailed photochemical studies suggest a single-step dissociation of L-L from the bis-thioether (SPH) complex [1] and diamine (TMEN) complex [2], while no photosubstitution was observed for [3] and [4]. Complex [1] and [2] demonstrated a dual role, involving both photosubstitution and 1O2 generation, while [3] and [4] solely exhibited poor to moderate 1O2 production. The interplay of excited states leading to these behaviors was rationalized from the lifetimes of the 3MLCT excited states by using transient absorption spectroscopy, suggesting intricate relaxation dynamics and 1O2 generation upon excitation. Therefore, the photolabile complexes [1] and [2] could potentially act as dual photoreactive agents via the phototriggered release of L-L (PACT) and/or 1O2-mediated PDT mechanisms, while [4] primarily can be utilized as a PDT agent.

Transcendental Meditation Enriches Nurses' Authentic Presence Through Caring for Self and Others.

Purpose of Study: Given the enormity of the most recent challenges to clinician well-being, intensified by the pandemic, we decided to explore the influence of Transcendental Meditation® (TM)® on the well-being of clinical nurses. The purpose of our study was to use qualitative analysis to enhance our understanding of the experiences of clinical nurses who practiced TM, as viewed through the lens of our conceptual model and Watson's holistic unitary caring science theory. Design and Method: This qualitative study involved a thematic analysis of clinical nurses' written descriptions following the completion of the TM program during the COVID-19 pandemic. Findings: The nurse participants shared their experiences with the practice of TM as creating present moment focus, leading to enhanced self-care, and development of authentic presence with others. The overall theme uncovered in the analysis is that authentic presence is veritas (truth) in knowing, being, doing, and becoming. Conclusions: The findings were congruent with Watson's unitary caring science theory and provided illumination of the holistic value of TM as a self-care strategy for supporting nurses' well-being with the goal of retaining nurses in practice. When nurses care for themselves, they are more likely and able to care for others, thus helping them to enjoy their nursing careers.

Understanding the synergistic effect in green propellants 2-azido-N,N-dimethylethanamine and tetramethylethylenediamine: From drop test to gas-phase autoignition

Understanding the synergistic effect in green propellants 2-azido-N,N-dimethylethanamine and tetramethylethylenediamine: From drop test to gas-phase autoignition