Objective:To evaluate the accuracy of six-dimensional(6D)treatment couches in minimizing setup errors compared with three-dimensional(3D)treatment couches during radiotherapy for lung cancer patients with brain metast...Objective:To evaluate the accuracy of six-dimensional(6D)treatment couches in minimizing setup errors compared with three-dimensional(3D)treatment couches during radiotherapy for lung cancer patients with brain metastases.Methods:A retrospective analysis was conducted on 40 lung cancer patients with brain metastases who received stereotactic radiotherapy(SRS/SRT)for brain metastases.The cohort was divided into two groups based on the availability of treatment units at the time of planning:20 patients were treated using a 3D couch,and 20 patients with a 6D couch.Daily cone-beam computed tomography(CBCT)registration was used to measure residual setup errors in the x,y,and z axes at two key cranial anatomical landmarks,specifically the internal acoustic meatus(IAM)and crista galli(CG),for both groups.The Shapiro-Wilk test was applied to assess the normality of the data,and the Mann-Whitney U test was performed to determine statistical differences between the two groups,with Bonferroni correction for multiple comparisons.Results:Baseline data indicated that the two groups were well-balanced in terms of gender,age,and distribution of pathological types,number of brain metastases,maximum metastases volume,and relative distance between metastases and isocenter(P>0.05).Setup error data in all directions(IAM_x/y/z,CG_x/y/z)did not follow a normal distribution(P<0.05).The Mann-Whitney U test revealed that setup errors in the 6D group were significantly smaller than those in the 3D group across all directions(IAM_x/y/z,CG_x/y/z,all P<0.001).The mean error reduction exceeded 1 mm in all directions,with the most significant difference observed in the CG_X direction:2.2(1.3,3.3)mm in the 3D group versus 0.3(0.2,0.5)mm in the 6D group,representing a difference of 1.9 mm.Conclusion:The six-dimensional(6D)treatment couch effectively minimizes residual setup errors,especially rotational ones,in radiotherapy for lung cancer patients with brain metastases.展开更多
Nanoporous silicon is a promising anode material for high energy density batteries due to its high cycling stability and high tap density compared to other nanostructured anode materials.However,the high cost of synth...Nanoporous silicon is a promising anode material for high energy density batteries due to its high cycling stability and high tap density compared to other nanostructured anode materials.However,the high cost of synthesis and low yield of nanoporous silicon limit its practical application.Here,we develop a scalable,low-cost top-down process of controlled oxidation of Mg2Si in the air,followed by HCl removal of MgO to generate nanoporous silicon without the use of HF.By controlling the synthesis conditions,the oxygen content,grain size and yield of the porous silicon are simultaneously optimized from commercial standpoints.In situ environmental transmission electron microscopy reveals the reaction mechanism;the Mg2Si microparticle reacts with O2 to form MgO and Si,while preventing SiO2 formation.Owing to the low oxygen content and microscale secondary structure,the nanoporous silicon delivers a higher initial reversible capacity and initial Coulombic efficiency compared to commercial Si nanoparticles(3,033 mAh/g vs.2,418 mAh/g,84.3%vs.73.1%).Synthesis is highly scalable,and a yield of 90.4%is achieved for the porous Si nanostructure with the capability to make an excess of 10 g per batch.Our synthetic nanoporous silicon is promising for practical applications in next generation lithium-ion batteries.展开更多
Lithium-ion batteries are approaching their theoretical limit and can no longer keep up with the increasing demands of human society.Lithium-sulfur batteries,with a high theoretical specific energy,are promising candi...Lithium-ion batteries are approaching their theoretical limit and can no longer keep up with the increasing demands of human society.Lithium-sulfur batteries,with a high theoretical specific energy,are promising candidates for next generation energy storage.However,the use of Li metal in Li-S batteries compromises both safety and performance,enabling dendrite formation and causing fast capacity degradation.Previous studies have probed alternative battery systems to replace the metallic Li in Li-S system,such as a Si/Li2S couple,with limited success in performance.Recently,there is a focus on red P as a favorable anode material to host Li.Here,we establish a novel battery scheme by utilizing a P/C nanocomposite anode and pairing it with a Li2S coated carbon nanofiber cathode.We find that red P anode can be compatible in ether-based electrolyte systems and can be successfully coupled to a Li2S cathode.Our proof of concept full-cell displays remarkable specific capacity,rate and cycling performances.We expect our work will provide a useful alternative system and valuable insight in the quest for next generation energy storage devices.展开更多
Double-sided metal-oxide-semiconductor field-effect-transistor processing is demonstrated for the first time on an ultrathin crystalline silicon substrate of 6-20μm in a 100 mm diameter wafer format without a carrier...Double-sided metal-oxide-semiconductor field-effect-transistor processing is demonstrated for the first time on an ultrathin crystalline silicon substrate of 6-20μm in a 100 mm diameter wafer format without a carrier wafer,the thinnest freestanding silicon wafers ever fabricated.The compatibility of the flexible material with conventional semiconductor processing tools is enabled by supporting an interior ultrathin silicon with a surrounding thicker ring of silicon.Currentvoltage characteristics of transistors on ultrathin silicon show performance as expected from bulk silicon,with electron mobility^1500 cm^2 V^−1 second^−1.Mechanical measurements quantify the handleability.展开更多
文摘Objective:To evaluate the accuracy of six-dimensional(6D)treatment couches in minimizing setup errors compared with three-dimensional(3D)treatment couches during radiotherapy for lung cancer patients with brain metastases.Methods:A retrospective analysis was conducted on 40 lung cancer patients with brain metastases who received stereotactic radiotherapy(SRS/SRT)for brain metastases.The cohort was divided into two groups based on the availability of treatment units at the time of planning:20 patients were treated using a 3D couch,and 20 patients with a 6D couch.Daily cone-beam computed tomography(CBCT)registration was used to measure residual setup errors in the x,y,and z axes at two key cranial anatomical landmarks,specifically the internal acoustic meatus(IAM)and crista galli(CG),for both groups.The Shapiro-Wilk test was applied to assess the normality of the data,and the Mann-Whitney U test was performed to determine statistical differences between the two groups,with Bonferroni correction for multiple comparisons.Results:Baseline data indicated that the two groups were well-balanced in terms of gender,age,and distribution of pathological types,number of brain metastases,maximum metastases volume,and relative distance between metastases and isocenter(P>0.05).Setup error data in all directions(IAM_x/y/z,CG_x/y/z)did not follow a normal distribution(P<0.05).The Mann-Whitney U test revealed that setup errors in the 6D group were significantly smaller than those in the 3D group across all directions(IAM_x/y/z,CG_x/y/z,all P<0.001).The mean error reduction exceeded 1 mm in all directions,with the most significant difference observed in the CG_X direction:2.2(1.3,3.3)mm in the 3D group versus 0.3(0.2,0.5)mm in the 6D group,representing a difference of 1.9 mm.Conclusion:The six-dimensional(6D)treatment couch effectively minimizes residual setup errors,especially rotational ones,in radiotherapy for lung cancer patients with brain metastases.
基金This work was supported by Samsung SDI.Part of this work was performed at the Stanford Nano Shared Facilities(SNSF)Stanford Nanofabrication Facility(SNF).
文摘Nanoporous silicon is a promising anode material for high energy density batteries due to its high cycling stability and high tap density compared to other nanostructured anode materials.However,the high cost of synthesis and low yield of nanoporous silicon limit its practical application.Here,we develop a scalable,low-cost top-down process of controlled oxidation of Mg2Si in the air,followed by HCl removal of MgO to generate nanoporous silicon without the use of HF.By controlling the synthesis conditions,the oxygen content,grain size and yield of the porous silicon are simultaneously optimized from commercial standpoints.In situ environmental transmission electron microscopy reveals the reaction mechanism;the Mg2Si microparticle reacts with O2 to form MgO and Si,while preventing SiO2 formation.Owing to the low oxygen content and microscale secondary structure,the nanoporous silicon delivers a higher initial reversible capacity and initial Coulombic efficiency compared to commercial Si nanoparticles(3,033 mAh/g vs.2,418 mAh/g,84.3%vs.73.1%).Synthesis is highly scalable,and a yield of 90.4%is achieved for the porous Si nanostructure with the capability to make an excess of 10 g per batch.Our synthetic nanoporous silicon is promising for practical applications in next generation lithium-ion batteries.
文摘Lithium-ion batteries are approaching their theoretical limit and can no longer keep up with the increasing demands of human society.Lithium-sulfur batteries,with a high theoretical specific energy,are promising candidates for next generation energy storage.However,the use of Li metal in Li-S batteries compromises both safety and performance,enabling dendrite formation and causing fast capacity degradation.Previous studies have probed alternative battery systems to replace the metallic Li in Li-S system,such as a Si/Li2S couple,with limited success in performance.Recently,there is a focus on red P as a favorable anode material to host Li.Here,we establish a novel battery scheme by utilizing a P/C nanocomposite anode and pairing it with a Li2S coated carbon nanofiber cathode.We find that red P anode can be compatible in ether-based electrolyte systems and can be successfully coupled to a Li2S cathode.Our proof of concept full-cell displays remarkable specific capacity,rate and cycling performances.We expect our work will provide a useful alternative system and valuable insight in the quest for next generation energy storage devices.
基金This work was performed at the Stanford Nano Shared Facilities and at the Stanford Nanofabrication Facility.R.A.L.thank the Fannie and John Hertz Foundation,the National Science Foundation Graduate Research Fellowship Program,and the Stanford Graduate Fellowship Program.
文摘Double-sided metal-oxide-semiconductor field-effect-transistor processing is demonstrated for the first time on an ultrathin crystalline silicon substrate of 6-20μm in a 100 mm diameter wafer format without a carrier wafer,the thinnest freestanding silicon wafers ever fabricated.The compatibility of the flexible material with conventional semiconductor processing tools is enabled by supporting an interior ultrathin silicon with a surrounding thicker ring of silicon.Currentvoltage characteristics of transistors on ultrathin silicon show performance as expected from bulk silicon,with electron mobility^1500 cm^2 V^−1 second^−1.Mechanical measurements quantify the handleability.
