Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 8.720
Filtrar
1.
Drug Des Devel Ther ; 18: 919-929, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38560523

RESUMO

Background: Magnesium sulfate, an intravenous adjuvant, has recently attracted immense attention in multimodal analgesia. Previous studies confirmed the crucial role of magnesium sulfate in postoperative pain and nociceptive hypersensitivity. However, the effect of magnesium sulfate in multimodal analgesia on the quality of recovery (QoR) for elderly patients has not been thoroughly studied. Therefore, the present experiment aimed to investigate the effect of continuous intravenous magnesium sulfate on the quality of postoperative recovery in elderly patients undergoing total knee arthroplasty (TKA). Patients and Methods: In this study, a total of 148 patients scheduled to undergo unilateral total knee arthroplasty were randomized into a magnesium sulfate group (Group M, n=68) and a control group (Group C, n=66) using a double-blind, randomized controlled trial. Before induction of anesthesia, Group M received intravenous magnesium sulfate (40 mg/kg) for 15 min, followed by a continuous infusion (15 mg/kg) until the end of the procedure. In the same manner, Group C received an infusion of the same amount of isotonic saline using the same method as the Group M. Results: Compared with Group C, Group M had significantly better QoR-15 scores on postoperative day 1(POD1) than Group C (P <0.05). Analysis of the dimensions of QoR-15 scores indicated that Group M exhibited notably reduced levels of pain, and higher levels of emotional state and physical comfort than Group C (P <0.05). Furthermore, Group C had significantly higher numerical rating scale (NRS) scores at POD1 than Group M (P <0.05). Conclusion: For elderly patients undergoing knee arthroplasty, magnesium sulfate can be used as an adjuvant in a multimodal analgesic regimen to reduce early postoperative pain and improve the quality of early postoperative recovery.


Assuntos
Artroplastia do Joelho , Sulfato de Magnésio , Humanos , Idoso , Sulfato de Magnésio/uso terapêutico , Estudos Prospectivos , Analgésicos , Dor Pós-Operatória/tratamento farmacológico , Método Duplo-Cego , Analgésicos Opioides
2.
Acta Med Indones ; 56(1): 3-12, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38561891

RESUMO

BACKGROUND: Asthma is a disease characterized by chronic airway inflammation, however one-third of asthmatic cases did not respond adequately. Inhaled magnesium has been proposed as a treatment for unresponsive asthma cases. However, its role remains controversial. This review evaluates the effectiveness and safety of nebulized magnesium compared to standard therapy (Beta Agonist, Anticholinergic, Corticosteroid) in adults with acute asthma attacks. METHODS: The protocol has been registered in PROSPERO. A literature search was conducted through PubMed/MEDLINE, Cochrane, ProQuest, and Google Scholar, and using the keywords "inhaled magnesium" and "asthma". Manual searches were carried out through data portals. Journal articles included are randomized controlled trials. The assessment risk of bias was performed using Version 2 of the Cochrane risk-of-bias tool for randomized trials. RESULTS: There are five articles included in this review. There is no significant difference in readmission rate and oxygen saturation in the magnesium group compared to control (RR 1; 95% CI 0.92 to 1,08; p= 0,96 and MD 1,82; 95% CI -0.89 to 4.53; p= 0.19, respectively). There is a significant reduction of respiratory rate and clinical severity in magnesium (MD -1,72; 95% CI -3,1 to 0.35; p= 0.01, RR 0.29; 95% CI 0.17 to 0.69; p <0.001, respectively). There was a higher risk of side effects in the magnesium group (HR 1.56; 95%CI 1.05 to 2.32; p= 0.03). However, the side effects are relatively mild such as hypotension and nausea. CONCLUSION: Inhaled magnesium improves the outcome of asthmatic patients, especially in lung function, clinical severity, and respiratory rate. Moreover, inhaled magnesium is safe to be given.


Assuntos
Antiasmáticos , Asma , Adulto , Humanos , Magnésio/uso terapêutico , Antiasmáticos/efeitos adversos , Asma/tratamento farmacológico , Hospitalização , Quimioterapia Combinada
3.
Cureus ; 16(3): e55301, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38562367

RESUMO

Dermatofibrosarcoma protuberans (DFSP) is a rare, locally aggressive soft tissue sarcoma of the skin. DFSP typically presents as an asymptomatic, firm plaque in its earliest stage, gradually enlarging over months to years. This case report delineates a singular instance involving a 66-year-old female patient previously diagnosed with and treated for DFSP. The individual presented with a recurrent history of hospital admissions, manifesting symptoms of loose stools, generalised weakness, and diminished appetite. Investigations revealed persistent hypomagnesemia. The patient was treated with magnesium correction. Eventually, all complaints were resolved, and the patient was discharged satisfactorily. This case report aims to elucidate an exceptional correlation between DFSP and hypomagnesemia, characterised as its paraneoplastic syndrome (PNS). This study intends to comprehensively outline the clinical manifestations, diagnostic approaches, and therapeutic interventions pertaining to this distinct association.

4.
Cureus ; 16(3): e55502, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38571856

RESUMO

Guided bone regeneration (GBR) plays a crucial role in the augmentation of alveolar bone, especially in cases of dental implants. The main principle behind using membranes in guided tissue regeneration (GTR) is to prevent epithelial downgrowth as well as connective tissue on the root surface. However, the membranes lack some major properties, such as osteogenic and antimicrobial properties. Magnesium (Mg) is one of the biodegradable materials that is gaining interest because of its favourable mechanical properties and biocompatibility. It also possesses pro-osteogenic properties and significant inhibition of biofilm formation and maturation. These features have attracted increasing interest in using magnesium oxide nanoparticles in GBR membrane applications. This systematic review assesses the osteogenic potential of magnesium oxide nanoparticles in periodontal bone regeneration. The literature search used PubMed, PubMed Central, Medline, and Cochrane databases to examine systematic reviews published till March 2023. Seven articles were included based on the selection criteria. We included all in vitro and in vivo clinical studies based on the osteogenic potential of magnesium oxide nanoparticles in periodontal bone regeneration. The seven studies provided evidence that magnesium oxide nanoparticles, when incorporated in any substrate, showed higher osteogenic potential in terms of higher alkaline phosphatase levels, bone volume fraction, and bone mineral density. The optimum concentration of magnesium oxide can be an ideal additive to various substrates to promote bone regeneration. Because most of the studies were conducted on calvarial defects, further studies should focus only on bone regeneration related to periodontal regeneration.

5.
Clin Kidney J ; 17(4): sfae046, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38572502

RESUMO

Background: The association between hypo- and/or hypermagnesaemia and cardiovascular (CV) outcomes or mortality has shown conflicting results in chronic kidney disease (CKD) and has been conducted on total magnesium (tMg) levels. Thus, the objectives of the present study were to (i) describe the serum ionized Mg (iMg) concentration in patients at various CKD stages, (ii) measure the correlation between iMg and tMg concentrations, (iii) identify their associated factors and (iv) determine whether serum tMg and/or iMg concentrations are associated with major adverse cardiovascular events (MACE) and mortality before kidney replacement therapy in CKD patients. Methods: Chronic Kidney Disease-Renal Epidemiology and Information Network (CKD-REIN) is a prospective cohort of CKD patients with an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2. Baseline iMg and tMg serum concentrations were centrally measured. Adjusted cause-specific Cox proportional hazard models were used to estimate hazard ratios (HRs) for first MACE and for mortality. Results: Of the 2419 included patients, median age was 68 years, and the mean eGFR was 34.8 mL/min/1.73 m2. Concentrations of serum iMg and tMg were strongly correlated (r = 0.89, P < .001) and were independently associated with eGFR. The adjusted HR [95% confidence interval (CI)] for MACE associated with the baseline serum tMg level was 1.27 (0.95; 1.69) for patients in Tertile 1 and 1.56 (1.18; 2.06) for patients in Tertile 3, relative to patients in Tertile 2. The HR (95% CI) of death according to serum tMg concentration was increased in Tertile 3 [1.48 (1.11; 1.97)]. The adjusted risk for MACE and mortality (all-cause or CV) associated with the baseline serum iMg level was not significantly different between tertiles. Conclusions: Our analysis of a large cohort of patients with moderate-to-advanced CKD demonstrated that individuals with higher serum tMg concentrations, although still within the normal range, had a greater likelihood of MACE and mortality. However, serum iMg levels were not associated with these outcomes.

6.
Heliyon ; 10(7): e28913, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38596064

RESUMO

Magnesium phosphate cement (MPC) is a high-performance repairing material suitable for the interfacial disease of slab track. In this study, the early properties of MPC were optimized using central composite design (CCD) approach based on response surface methodology (RSM). Three factors with five levels and three responses were considered. The significance of the factors and their interactions were verified by using analysis of variance (ANOVA). The result show that the mass ratio of water-to-binder (W/b) affects fluidity, while the mass ratio of magnesia-to-phosphate (M/P) and borax-to-magnesia (B/M) impact the setting time of MPC. Higher W/b results in higher fluidity, while an increase in M/P reduces the setting time by increasing the neutralization reaction. Borax addition retards the reaction, prolonging the setting time. The three factors significantly affect the early compressive strength of MPC. At M/P = 3.5, the interweaving of MgO and K-struvite (MKP) forms a dense network structure, enhancing the strength. Borax and W/b interact to affect compressive strength, with borax retarding MKP crystal growth and higher W/b reducing compactness. Combined with microscopic property test, the strength generation mechanism of MPC with optimized mixing ratio was revealed, And the feasibility of field application of MPC was verified by strength test.

7.
World J Orthop ; 15(3): 215-229, 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38596190

RESUMO

BACKGROUND: In recent years, the use of Magnesium alloy implants have gained renewed popularity, especially after the first commercially available Conformité Européenne approved Magnesium implant became available (MAGNEZIX® CS, Syntellix) in 2013. AIM: To document our clinical and radiographical outcomes using magnesium implants in treating peri-articular elbow fractures. METHODS: Our paper was based on a retrospective case series design. Intra-operatively, a standardized surgical technique was utilized for insertion of the magnesium implants. Post - operatively, clinic visits were standardized and physical exam findings, functional scores, and radiographs were obtained at each visit. All complications were recorded. RESULTS: Five patients with 6 fractures were recruited (2 coronoid, 3 radial head and 1 capitellum). The mean patient age and length of follow up was 54.6 years and 11 months respectively. All fractures healed, and none exhibited loss of reduction or complications requiring revision surgery. No patient developed synovitis of the elbow joint or suffered electrolytic reactions when titanium implants were used concurrently. CONCLUSION: Although there is still a paucity of literature available on the subject and further studies are required, magnesium implants appear to be a feasible tool for fixation of peri-articular elbow fractures with promising results in our series.

8.
Mitochondrion ; : 101877, 2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38599304

RESUMO

Mitochondrial Ca2+ uptake is essential in regulating bioenergetics, cell death, and cytosolic Ca2+ transients. Mitochondrial Calcium Uniporter (MCU) mediates the mitochondrial Ca2+ uptake. Though MCU regulation by MICUs is unequivocally established, there needs to be more knowledge of whether divalent cations regulate MCU. Here, we set out to understand the mitochondrial matrix Mg2+-dependent regulation of MCU activity. We showed that decreased matrix [Mg2+] is associated with increased MCU activity and significantly prompted mitochondrial permeability transition pore opening. Our findings support the critical role of mMg2+ in regulating MCU activity.

9.
Environ Res ; : 118894, 2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38599449

RESUMO

Microplastics, an invisible threat, are emerging as serious pollutants that continuously affect health by interrupting/contaminating the human cycle, mainly involving food, water, and air. Such serious scenarios raised the demand for developing efficient sensing systems to detect them at an early stage efficiently and selectively. In this direction, the proposed research reports an electrochemical hexamethylenetetramine (HMT) sensing utilizing a sensing platform fabricated using chitosan-magnesium oxide nanosheets (CHIT-MgO NS) nanocomposite. HMT is considered as a hazardous microplastic, which is used as an additive in plastic manufacturers and has been selected as a target analyte. To fabricate sensing electrodes, a facile co-precipitation technique was employed to synthesize MgO NS, which was further mixed with 1% CHIT solution to form a CHIT_MgO NS composite. Such prepared nanocomposite solution was then dropped cast to an indium tin oxide (ITO) to fabricate CHIT_MgO NS/ITO sensing electrode to detect HMT electrochemically using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. To determine the limit of detection (LOD) and sensitivity, DPV was performed. The resulting calibrated curve for HMT, ranging from 0.5 µM to 4.0 µM, exhibited a sensitivity of 12.908 µA (µM)-1 cm-2 with a detection limit of 0.03 µM and a limit of quantitation (LOQ) of 0.10 µM. Further, the CHIT_MgO NS/ITO modified electrode was applied to analyze HMT in various real samples, including river water, drain water, packaged water, and tertiary processed food. The results demonstrated the method's high sensitivity and suggested its potential applications in the field of microplastic surveillance, with a focus on health management.

10.
Am J Clin Nutr ; 2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38599521

RESUMO

BACKGROUND: Hypomagnesemia is commonly observed in individuals with diabetes, but how diabetes medications alter magnesium (Mg) status remains unclear. OBJECTIVE: We aimed to 1) examine the association between diabetes medication and hypomagnesemia and 2) evaluate whether serum Mg mediates the association between diabetes medication and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) in a prospective cohort. METHODS: Adults from the Boston Puerto Rican Health Study were included (n=1106). Multivariable logistic regression models were used to estimate odds ratio (OR) and 95% confidence interval (CI) for cross-sectional association between diabetes medication and hypomagnesemia (serum Mg < 0.75 mmol/L). Longitudinal mediation analysis was performed to evaluate the direct and indirect (via serum Mg) associations between diabetes medication and 4-year (y) HOMA-IR in 341 participants with baseline hemoglobin A1c (HbA1c) ≥ 6.5%. RESULTS: Mean age at baseline was 59.0±7.6 y, with 28.0% male and 45.8% with hypomagnesemia. Use of metformin [OR (95% CI) = 3.72 (2.53, 5.48)], sulfonylureas [OR (95% CI) = 1.68 (1.00, 2.83)], and glitazones [OR (95% CI) = 2.09 (1.10, 3.95)], but not insulin, was associated with higher odds of hypomagnesemia. Use of multiple diabetes medications and longer duration of use were associated with higher odds of hypomagnesemia. Serum Mg partially mediated the association between metformin and HOMA-IR [indirect association: ß (95% CI) = 1.11 (0.15, 2.07)], which weakened the direct association [ß (95% CI) = -5.16 (-9.02, -1.30)] by 22% [total association: ß (95% CI) = -4.05 (-7.59, -0.51)]. Similarly, serum Mg mediated 17% of the association between sulfonylureas and elevated HOMA-IR. However, the mediation by serum Mg was weak for insulin and glitazones. CONCLUSIONS: Diabetes medication, especially metformin, was associated with elevated odds of hypomagnesemia, which may weaken the association between metformin and lowering of HOMA-IR. The causal inference needs to be confirmed in further studies.

11.
Artigo em Inglês | MEDLINE | ID: mdl-38602634

RESUMO

Nanoparticles, particularly magnesium oxide nanoparticles (MgO-NPs), are increasingly utilized in various fields, yet their potential impact on cellular systems remains a topic of concern. This study aimed to comprehensively investigate the molecular mechanisms underlying MgO-NP-induced cellular impairment in Saccharomyces cerevisiae, with a focus on cell wall integrity, endoplasmic reticulum (ER) stress response, mitochondrial function, lipid metabolism, autophagy, and epigenetic alterations. MgO-NPs were synthesized through a chemical reduction method, characterized for morphology, size distribution, and elemental composition. Concentration-dependent toxicity assays were conducted to evaluate the inhibitory effect on yeast growth, accompanied by propidium iodide (PI) staining to assess membrane damage. Intracellular reactive oxygen species (ROS) accumulation was measured, and chitin synthesis, indicative of cell wall perturbation, was examined along with the expression of chitin synthesis genes. Mitochondrial function was assessed through Psd1 localization, and ER structure was analyzed using dsRed-HDEL marker. The unfolded protein response (UPR) pathway activation was monitored, and lipid droplet formation and autophagy induction were investigated. Results demonstrated a dose-dependent inhibition of yeast growth by MgO-NPs, with concomitant membrane damage and ROS accumulation. Cell wall perturbation was evidenced by increased chitin synthesis and upregulation of chitin synthesis genes. MgO-NPs impaired mitochondrial function, disrupted ER structure, and activated the UPR pathway. Lipid droplet formation and autophagy were induced, indicating cellular stress responses. Additionally, MgO-NPs exhibited differential cytotoxicity on histone mutant strains, implicating specific histone residues in cellular response to nanoparticle stress. Immunoblotting revealed alterations in histone posttranslational modifications, particularly enhanced methylation of H3K4me. This study provides comprehensive insights into the multifaceted effects of MgO-NPs on S. cerevisiae, elucidating key molecular pathways involved in nanoparticle-induced cellular impairment. Understanding these mechanisms is crucial for assessing nanoparticle toxicity and developing strategies for safer nanoparticle applications.

13.
Chemistry ; : e202400418, 2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38593253

RESUMO

Zerovalent magnesium (Mg(0)) nanoparticles are prepared in the liquid phase (THF) by reduction of MgBr2 either with lithium naphthalenide ([LiNaph]) or lithium biphenyl ([LiBP]). [LiBP]-driven reduction results in smaller Mg(0) nanoparticles (10.3±1.7 nm) than [LiNaph]-driven reduction (28.5±4 nm). The as-prepared Mg(0) nanoparticles are monocrystalline (d101 = 245±5 pm) for both types of reduction. Their reactivity is probed by liquid-phase reaction (THF, toluene) in suspension near room temperature (20-120 °C) with 1-bromoadamantane (AdBr), chlortriphenylsilane (Ph3SiCl), trichlorphenylsilane (PhSiCl3), 9H-carbazole (Hcbz), 7-azaindole (Hai), 1,8-diaminonaphthalene (H4nda) and N,N'-bis(α-pyridyl)-2,6-diaminopyridine (H4tpda) as exemplary starting materials. The reactions result in the formation of 1,1'-biadamantane (1), [MgCl2(thf)2]×Ph6Si2 (2), [Mg9(thf)14Cl18] (3), [Mg(cbz)2(thf)3] (4), [Mg4O(ai)6]×1.5 C7H8 (5), [Mg4(H2nda)4(thf)4] (6) and [Mg3(tpda)3] (7) with 40-80 % yield. 1 and 2 show the reactivity of Mg(0) nanoparticles for C-C and Si-Si coupling reactions with sterically demanding starting materials. 3-7 represent new coordination compounds using sterically demanding N-H-acidic amines as starting materials. The formation of multinuclear Mg2+ complexes with multidentate ligands illustrates the potential of the oxidative approach to obtain novel compounds with Mg(0) nanoparticles in the liquid phase.

14.
Anal Bioanal Chem ; 2024 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-38594392

RESUMO

Messenger RNA (mRNA) vaccines represent a landmark in vaccinology, especially with their success in COVID-19 vaccines, which have shown great promise for future vaccine development and disease prevention. As a platform technology, synthetic mRNA can be produced with high fidelity using in vitro transcription (IVT). Magnesium plays a vital role in the IVT process, facilitating the phosphodiester bond formation between adjacent nucleotides and ensuring accurate transcription to produce high-quality mRNA. The development of the IVT process has prompted key inquiries about in-process characterization of magnesium ion (Mg++) consumption, relating to the RNA polymerase (RNAP) activation, fed-batch mode production yield, and mRNA quality. Hence, it becomes crucial to monitor the free Mg++ concentration throughout the IVT process. However, no free Mg++ analysis method has been reported for complex IVT reactions. Here we report a robust capillary zone electrophoresis (CZE) method with indirect UV detection. The assay allows accurate quantitation of free Mg++ for the complex IVT reaction where it is essential to preserve IVT samples in their native-like state during analysis to avoid dissociation of bound Mg complexes. By applying this CZE method, the relationships between free Mg++ concentration, the mRNA yield, and dsRNA impurity level were investigated. Such mechanistic understanding facilitates informed decisions regarding the quantity and timing of feeding starting materials to increase the yield. Furthermore, this approach can serve as a platform method for analyzing the free Mg++ in complex sample matrices where preserving the native-like state of Mg++ binding is key for accurate quantitation.

15.
Eur J Nutr ; 2024 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-38597977

RESUMO

BACKGROUND: Consistent evidence shows that magnesium (Mg) intake is associated with lower blood pressure (BP), and that lower BP is associated with improved cerebral health. However, recent findings indicate that the positive effect of dietary Mg intake on cerebral health is not mediated by a decrease in BP. As Mg's anti-inflammatory action is a plausible alternative mechanism, the objective of this study was to investigate the associations between Mg intake and inflammation to determine whether it mediates any neuroprotective effect. METHODS: Participants from the UK Biobank (n = 5775, aged 40-73 years, 54.7% female) were assessed for dietary magnesium using an online food questionnaire, brain and white matter lesion (WML) volumes were segmented with FreeSurfer software, and inflammation markers including high-sensitivity C-reactive protein (hs-CRP), leukocyte, erythrocyte count, and Glycoprotein acetylation (GlycA) were measured using specific laboratory techniques such as immunoturbidimetry, automated cell counting, and nuclear magnetic resonance. Hierarchical linear regression models were performed to investigate the association between dietary Mg, and inflammatory markers and between dietary Mg, brain and WMLs volumes. Mediation analysis was performed to test a possible mediation role of inflammation on the association between dietary Mg and brain and WMLs volumes. RESULTS: Higher dietary Mg intake was associated with lower inflammation: hs-CRP level (- 0.0497%; 95% confidence interval [CI] - 0.0497%,  - 0.0199%) leukocytes count (- 0.0015%; 95%CI - 0.00151%,  - 0.0011%), and GlycA (- 0.0519%; 95%CI - 0.1298%,  - 0.0129%). Moreover, higher dietary Mg intake was associated with larger grey matter volume (0.010%; 95%CI 0.004%, 0.017%), white matter volume (0.012%; 95%CI 0.003,  0.022) and right hippocampal volume (0.002%; 95%CI 0.0007, -0.0025%). Lower hs-CRP levels mediated the positive association between higher dietary Mg intake and larger grey matter volume. CONCLUSIONS: The anti-inflammatory effects of dietary Mg intake in the general population, appears to mediate its neuroprotective effect.

16.
Sci Rep ; 14(1): 8223, 2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38589386

RESUMO

Supercapacitors have emerged as highly efficient energy storage devices, relying on electrochemical processes. The performance of these devices can be influenced by several factors, with key considerations including the selection of electrode materials and the type of electrolyte utilized. Transition metal oxide electrodes are commonly used in supercapacitors, as they greatly influence the electrochemical performance of these devices. Nonetheless, ferrites' low energy density poses a limitation. Hence, it is crucial to create electrode materials featuring unique and distinct structures, while also exploring the ideal electrolyte types, to enhance the electrochemical performance of supercapacitors incorporating magnesium ferrites (MF). In this study, we effectively prepared magnesium ferrites (MgFe2O4) supported on activated carbon (AC) derived from orange peels (OP) using a simple hydrothermal method. The resulting blends underwent comprehensive characterization employing various methods, including FTIR, XRD, TEM, SEM, EDX, and mapping analysis. Moreover, the electrochemical performance of MgFe2O4@AC composites was evaluated using GCD and CV techniques. Remarkably, the MF45-AC electrode material showed exceptional electrochemical behavior, demonstrating a specific capacitance of 870 F·g-1 within current density of 1.0 A g-1 and potential windows spanning from 0 to 0.5 V. Additionally, the prepared electrodes displayed exceptional cycling stability, with AC, MF, and MF45-AC retaining 89.6%, 94.2%, and 95.1% of their initial specific capacitance, respectively, even after 5000 cycles. These findings underscore the potential of MF-AC composites as superior electrode materials for supercapacitors. The development of such composites, combined with tailored electrolyte concentrations, holds significant promise for advancing the electrochemical performance and energy density of supercapacitor devices.

17.
Materials (Basel) ; 17(3)2024 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-38591406

RESUMO

This article provides a detailed review of the types of magnesium wheels available in the industry and the current methods of the wheels' production. The past several years have seen a significant development of magnesium-based lightweight alloys employed as a structural material for modern light vehicles. Magnesium alloys are characterized by their low density while maintaining good mechanical properties. The use of these alloys in the industry enables vehicles' weight reduction while increasing their technical parameters. The first part of the article presents the unique properties of magnesium alloys that determine the application of this material for lightweight vehicle wheels. The advantages of using magnesium wheels over aluminum wheels are also presented. Next, a classification of the types of magnesium wheels was made in regard to their construction, applications, and manufacturing methods. At present, magnesium wheels by construction can be classified according to their geometry as single parts or assembled parts. In reference to geometry, wheels can have different shapes: classic, multi-spoke, with holes, or with frames. Depending on the geometry used, magnesium wheels can have different parameters, such as their mounting hole spacing, wheel diameters, or rim width. Considering the applications in various industries, main distinctions can be made between magnesium wheels for automobiles, motorcycles, bicycles, and wheelchairs. Magnesium wheels can also be categorized in regards to the manufacturing methods: casting, machining, forging, and hybrid manufacturing. The second part of the article focuses on the analysis of magnesium alloy wheel-manufacturing technologies used in the industry and developed by research centers. This article discusses these manufacturing technologies in detail and indicates prospective directions for further development.

18.
Materials (Basel) ; 17(3)2024 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-38591444

RESUMO

A new composite with a core-shell structure based on magnesium hydride and finely dispersed aluminum powder with an aluminum oxide shell was mechanically synthesized. We used magnesium chips to produce magnesium hydride and aluminum wire after exploitation to produce nano-sized aluminum powder. The beginning of the hydrogen release from the composite occurred at the temperature of 117 °C. The maximum desorption temperature from the MgH2-EEWAl composite (10 wt.%) was 336 °C, compared to pure magnesium hydride-417 °C. The mass content of hydrogen in the composite was 5.5 wt.%. The positive effect of the aluminum powder produced by the electric explosion of wires method on reducing the activation energy of desorption was demonstrated. The composite's desorption activation energy was found to be 109 ± 1 kJ/mol, while pure magnesium hydride had an activation energy of 161 ± 2 kJ/mol. The results obtained make it possible to expand the possibility of using magnesium and aluminum waste for hydrogen energy.

19.
Chemistry ; : e202401005, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38622992

RESUMO

In this contribution, we present "Birch-type", and other reductions of simple arenes by the potassium salt of an anionic magnesium dinitrogen complex, [{K(TCHPNON)Mg}2(µ-N2)] (TCHPNON = 4,5-bis(2,4,6-tricyclohexylanilido)-2,7-diethyl-9,9-dimethyl-xanthene), which acts as a masked dimagnesium(I) diradical in these reactions. This reagent is non-hazardous, easy-to-handle, and readily provides access to 1,4-cyclohexadiene reduction products under relatively mild reaction conditions. This system works effectively to reduce benzene, naphthalene and anthracene through magnesium-bound "Birch-type" reduction intermediates. Cyclohexadiene products can be subsequently released from the magnesium centres by protonolysis with methanol. In contrast, the reduction of substituted arenes is less selective and involves competing reaction pathways. For toluene and 1,3,5-triphenylbenzene, the structural authentication of "Birch-type" reduction intermediates is conclusive, although the formation of corresponding 1,4-cyclohexadiene derivatives was low yielding. Reduction of anisole did not yield an isolable "Birch-type" intermediate, but instead gave a C-O activation product. Treating triphenylphosphine with [{K(TCHPNON)Mg}2(µ-N2)] resulted in the extrusion of both biphenyl and dinitrogen to afford a magnesium(II) phosphanide [{K(TCHPNON)Mg(µ-PPh2)}2]. Reduction of fluorobenzene proceeded via C‒F activation of the arene, and isolation of the magnesium(II) fluoride [{K(TCHPNON)Mg(µ-F)}2]. Finally, the two-electron reduction of 1,3,5,7-cyclooctatetraene (COT) with [{K(TCHPNON)Mg}2(µ-N2)] yielded a complex, [{K(TCHPNON)Mg}2(µ-COT)], incorporating the aromatic dianion (COT2-).

20.
Int J Biol Macromol ; 267(Pt 1): 131471, 2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38599419

RESUMO

The conversion of glucose into fructose can transform cellulose into high-value chemicals. This study introduces an innovative synthesis method for creating an MgO-based ordered mesoporous carbon (MgO@OMC) catalyst, aimed at the efficient isomerization of glucose into fructose. Throughout the synthesis process, lignin serves as the exclusive carbon precursor, while Mg2+ functions as both a crosslinking agent and a metallic active center. This enables a one-step synthesis of MgO@OMC via a solvent-induced evaporation self-assembly (EISA) method. The synthesized MgO@OMCs exhibit an impeccable 2D hexagonal ordered mesoporous structure, in addition to a substantial specific surface area (378.2 m2/g) and small MgO nanoparticles (1.52 nm). Furthermore, this catalyst was shown active, selective, and reusable in the isomerization of glucose to fructose. It yields 41 % fructose with a selectivity of up to 89.3 % at a significant glucose loading of 7 wt% in aqueous solution over MgO0.5@OMC-600. This performance closely rivals the current maximum glucose isomerization yield achieved with solid base catalysts. Additionally, the catalyst retains a fructose selectivity above 60 % even after 4 cycles, a feature attributable to its extended ordered mesoporous structure and the spatial confinement effect of the OMCs, bestowing it with high catalytic efficiency.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...