The ever-increasing demand for light weighted hard materials for transportation industries encouraged researchers to develop composites with excellent mechanical properties which can transform it into more economical ...The ever-increasing demand for light weighted hard materials for transportation industries encouraged researchers to develop composites with excellent mechanical properties which can transform it into more economical and eco-friendly.Reinforcing the metals with carbonaceous nanomaterials are progressively in focus due to their excellent capability to inculcate and tailor the properties of MMCs.In the present research,a hybrid nanocomposite of MWCNT-Graphene-AZ31 Mg alloy has been developed by using variable tool rotation speeds with friction stir processing(FSP).Optimized reinforcement ratio of 1.6%vol.MWCNT and 0.3%vol.of graphene have been used with variable tool rotation speeds,whereas other processing parameters are kept constant.The developed specimens were investigated using standard testing equipment for evaluating and comparing the mechanical properties on the basis of the microstructure of the processing regions and their morphological analysis,according to the ASTM standards.The obtained results revealed an improvement of 19.72%in microhardness and 77.5% of compressive strength in comparison with the base metal AZ 31 Magnesium alloy,with a tool rotational speed of 1400rpm.The values of tensile stress and percentage area reduction were recorded as less than that of the base metal matrix,but an increasing trend has been observed in the values of both with the improvement on rotational speeds of the tool.The effectual strengthening mechanisms are analyzed on the bases of SEM images and observed that discussed and found that grain refinement strengthening is the major contributor to the strength of the nanocomposite.展开更多
Cycloalkanes and cyclohexanols find diverse applications,including sustainable aviation fuel,fuel additives,and value-added chemicals.These compounds can be produced via complete or selective hydrodeoxygenation(HDO)of...Cycloalkanes and cyclohexanols find diverse applications,including sustainable aviation fuel,fuel additives,and value-added chemicals.These compounds can be produced via complete or selective hydrodeoxygenation(HDO)of lignin-derived phenolic monomers.In this study,a urea-assisted method was employed to control the size of Ru nanoparticles(NPs)and tune the surfaceactive sites on Ru metal supported on CN_(x).By adjusting the Ru-to-urea molar ratio,both the size of Ru NPs and the metallic-tooxide ratio of Ru were controlled,along with the incorporation of N atoms into the RuO_(2)surface coordination.In the absence of urea,the Ru/CN_(x)(1:0)catalyst,containing 4.8 nm Ru NPs,achieved complete HDO of 4-propyl guaiacol to n-propyl cyclohexane through ring saturation,followed by hydro-demethoxylation of the C–OCH_(3)group,and hydrogenolysis of the–OH group,with a 97.0%yield at an initial H_(2)pressure of 1.5 MPa,200℃,and 20 h in water.The final hydrogenolysis step was inhibited over the urea-assisted catalysts.The Ru/CN_(x)(1:8)catalyst,containing 3.1 nm Ru NPs,achieved a maximum selectivity of 67.6%for n-propyl cyclohexanol,along with complete conversion of 4-propyl guaiacol.Similar trends were observed in the product distribution when upgrading reductive catalytic fractionation bio-oil over Ru/CN_(x)(1:0)and Ru/CN_(x)(1:8).展开更多
Herein,one-pot chemocatalytic conversion of xylose to value-added C_(5)/C_(4) cyclic ethers over a novel ZrO_(2)-doped Ni-Pd catalyst supported on H-βzeolite was demonstrated.Optimized catalyst,namely,Ni_(2) Pd_(0.5)...Herein,one-pot chemocatalytic conversion of xylose to value-added C_(5)/C_(4) cyclic ethers over a novel ZrO_(2)-doped Ni-Pd catalyst supported on H-βzeolite was demonstrated.Optimized catalyst,namely,Ni_(2) Pd_(0.5)Zr_(1)/H-β(25),achieved a high xylose transformation(>99%)with high selectivities toward 2-methyltetrahydrofuran(48.6%)and tetrahydropyran(20.2%)under mild reaction conditions(200℃,1.0 MPa H_(2),and 2 h).Systematic investigation of the physicochemical properties of the catalyst revealed that ZrO_(2) doping induced O vacancies,enhanced H_(2) activation,and improved metal dispersion,thereby promoting hydrogenation and hydrodeoxygenation.In situ diffuse reflectance infrared Fourier transform spectroscopy using furfural and furfuryl alcohol probes confirmed preferential adsorption geometries and electronic interactions at metal-ZrO_(2) interfaces.Time-resolved and feedstock variation studies further elucidated the reaction mechanism and highlighted the roles of key intermediates.The proposed catalyst exhibited excellent recyclability with only a minor decline in performance after multiple xylose conversion cycles.This study provides mechanistic insights and design principles for the development of efficient multifunctional catalysts for biomass valorization.展开更多
Metastatic brain tumors undergo profound metabolic-epigenetic reprogramming driven by the unique constraints of the brain microenvironment.Hypoxia-inducible factor-1α(HIF1α)enhances glycolytic flux,lactate accumulat...Metastatic brain tumors undergo profound metabolic-epigenetic reprogramming driven by the unique constraints of the brain microenvironment.Hypoxia-inducible factor-1α(HIF1α)enhances glycolytic flux,lactate accumulation,and histone lactylation,collectively supporting metastatic colonization and immune evasion.Key metabolites including acetyl-CoA,S-adenosylmethionine(SAM),α-ketoglutarate(α-KG),fumarate,and 2-hydroxyglutarate(2-HG)-directly modify chromatin states by regulating histone acetyltransferases,DNA/histone methyltransferases,andα-KG dependent dioxygenases such as Ten-Eleven Translocation(TET)enzymes and lysine demethylases(KDMs).These metabolic shifts result in aberrant DNA methylation,histone lysine residue at position 27 on Histone H3(H3K27)trimethylation,and depletion of 5-hydroxymethylcytosine(5hmC),all of which are hallmark epigenetic alterations in brain metastasis and primary Central Nervous System(CNS)tumors.Additionally,the blood-brain barrier(BBB)and blood-tumor barrier(BTB)impose nutrient restrictions and induce metabolic dependency on glutamine,acetate,and lactate shuttling,thereby reshaping epigenetic enzyme activity.We synthesize current mechanistic evidence showing how metabolic pressures in the brain microenvironment remodel the epigenome to promote tumor plasticity,stemness,and therapeutic resistance.Understanding these coupled pathways reveals vulnerable nodes such as HIF1αsignaling,α-KG-dependent demethylation,and lactate-driven epigenetic remodeling that may be exploited for targeted treatment of metastatic brain tumors.The present review aims to provide in-depth insights into epigenetic regulation,including chromatin and histone modifications as well as noncoding RNAs and metabolic reprogramming,highlighting how the two interplay in the development and progression of metastatic brain tumors and their therapeutic potential.展开更多
文摘The ever-increasing demand for light weighted hard materials for transportation industries encouraged researchers to develop composites with excellent mechanical properties which can transform it into more economical and eco-friendly.Reinforcing the metals with carbonaceous nanomaterials are progressively in focus due to their excellent capability to inculcate and tailor the properties of MMCs.In the present research,a hybrid nanocomposite of MWCNT-Graphene-AZ31 Mg alloy has been developed by using variable tool rotation speeds with friction stir processing(FSP).Optimized reinforcement ratio of 1.6%vol.MWCNT and 0.3%vol.of graphene have been used with variable tool rotation speeds,whereas other processing parameters are kept constant.The developed specimens were investigated using standard testing equipment for evaluating and comparing the mechanical properties on the basis of the microstructure of the processing regions and their morphological analysis,according to the ASTM standards.The obtained results revealed an improvement of 19.72%in microhardness and 77.5% of compressive strength in comparison with the base metal AZ 31 Magnesium alloy,with a tool rotational speed of 1400rpm.The values of tensile stress and percentage area reduction were recorded as less than that of the base metal matrix,but an increasing trend has been observed in the values of both with the improvement on rotational speeds of the tool.The effectual strengthening mechanisms are analyzed on the bases of SEM images and observed that discussed and found that grain refinement strengthening is the major contributor to the strength of the nanocomposite.
基金supported by the Bio&Medical Technology Development Program of the National Research Foundation(NRF)funded by the Ministry of Science and ICT(MSIT),Republic of Korea(2022M3A9F3017700)Additional support from the the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Ministry of Trade,Industry&Energy,Republic of Korea is also acknowledged(RS-2024-00436868)the 10 C synchrotron beamline of the Pohang Acceleration Laboratory(PAL,Republic of Korea)under contact no.2024-3rd-10C-051。
文摘Cycloalkanes and cyclohexanols find diverse applications,including sustainable aviation fuel,fuel additives,and value-added chemicals.These compounds can be produced via complete or selective hydrodeoxygenation(HDO)of lignin-derived phenolic monomers.In this study,a urea-assisted method was employed to control the size of Ru nanoparticles(NPs)and tune the surfaceactive sites on Ru metal supported on CN_(x).By adjusting the Ru-to-urea molar ratio,both the size of Ru NPs and the metallic-tooxide ratio of Ru were controlled,along with the incorporation of N atoms into the RuO_(2)surface coordination.In the absence of urea,the Ru/CN_(x)(1:0)catalyst,containing 4.8 nm Ru NPs,achieved complete HDO of 4-propyl guaiacol to n-propyl cyclohexane through ring saturation,followed by hydro-demethoxylation of the C–OCH_(3)group,and hydrogenolysis of the–OH group,with a 97.0%yield at an initial H_(2)pressure of 1.5 MPa,200℃,and 20 h in water.The final hydrogenolysis step was inhibited over the urea-assisted catalysts.The Ru/CN_(x)(1:8)catalyst,containing 3.1 nm Ru NPs,achieved a maximum selectivity of 67.6%for n-propyl cyclohexanol,along with complete conversion of 4-propyl guaiacol.Similar trends were observed in the product distribution when upgrading reductive catalytic fractionation bio-oil over Ru/CN_(x)(1:0)and Ru/CN_(x)(1:8).
基金supported by the Bio&Medical Technology Development Program(no.RS-2022-NR067354)established by the National Research Foundation(NRF)funded by the Korean Ministry of Science and ICT(MSIT)+2 种基金an NRF grant funded by the Korean MSIT(no.RS-2023-00261322)Additional support from the Korea Institute of Energy Technology Evaluation and Planning(KETEP)the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea(RS-2024-00469587)was also appreciated。
文摘Herein,one-pot chemocatalytic conversion of xylose to value-added C_(5)/C_(4) cyclic ethers over a novel ZrO_(2)-doped Ni-Pd catalyst supported on H-βzeolite was demonstrated.Optimized catalyst,namely,Ni_(2) Pd_(0.5)Zr_(1)/H-β(25),achieved a high xylose transformation(>99%)with high selectivities toward 2-methyltetrahydrofuran(48.6%)and tetrahydropyran(20.2%)under mild reaction conditions(200℃,1.0 MPa H_(2),and 2 h).Systematic investigation of the physicochemical properties of the catalyst revealed that ZrO_(2) doping induced O vacancies,enhanced H_(2) activation,and improved metal dispersion,thereby promoting hydrogenation and hydrodeoxygenation.In situ diffuse reflectance infrared Fourier transform spectroscopy using furfural and furfuryl alcohol probes confirmed preferential adsorption geometries and electronic interactions at metal-ZrO_(2) interfaces.Time-resolved and feedstock variation studies further elucidated the reaction mechanism and highlighted the roles of key intermediates.The proposed catalyst exhibited excellent recyclability with only a minor decline in performance after multiple xylose conversion cycles.This study provides mechanistic insights and design principles for the development of efficient multifunctional catalysts for biomass valorization.
文摘Metastatic brain tumors undergo profound metabolic-epigenetic reprogramming driven by the unique constraints of the brain microenvironment.Hypoxia-inducible factor-1α(HIF1α)enhances glycolytic flux,lactate accumulation,and histone lactylation,collectively supporting metastatic colonization and immune evasion.Key metabolites including acetyl-CoA,S-adenosylmethionine(SAM),α-ketoglutarate(α-KG),fumarate,and 2-hydroxyglutarate(2-HG)-directly modify chromatin states by regulating histone acetyltransferases,DNA/histone methyltransferases,andα-KG dependent dioxygenases such as Ten-Eleven Translocation(TET)enzymes and lysine demethylases(KDMs).These metabolic shifts result in aberrant DNA methylation,histone lysine residue at position 27 on Histone H3(H3K27)trimethylation,and depletion of 5-hydroxymethylcytosine(5hmC),all of which are hallmark epigenetic alterations in brain metastasis and primary Central Nervous System(CNS)tumors.Additionally,the blood-brain barrier(BBB)and blood-tumor barrier(BTB)impose nutrient restrictions and induce metabolic dependency on glutamine,acetate,and lactate shuttling,thereby reshaping epigenetic enzyme activity.We synthesize current mechanistic evidence showing how metabolic pressures in the brain microenvironment remodel the epigenome to promote tumor plasticity,stemness,and therapeutic resistance.Understanding these coupled pathways reveals vulnerable nodes such as HIF1αsignaling,α-KG-dependent demethylation,and lactate-driven epigenetic remodeling that may be exploited for targeted treatment of metastatic brain tumors.The present review aims to provide in-depth insights into epigenetic regulation,including chromatin and histone modifications as well as noncoding RNAs and metabolic reprogramming,highlighting how the two interplay in the development and progression of metastatic brain tumors and their therapeutic potential.
