Acoustic holograms can recover wavefront stored acoustic field information and produce high-fidelity complex acoustic fields. Benefiting from the huge spatial information that traditional acoustic elements cannot matc...Acoustic holograms can recover wavefront stored acoustic field information and produce high-fidelity complex acoustic fields. Benefiting from the huge spatial information that traditional acoustic elements cannot match, acoustic holograms pursue the realization of high-resolution complex acoustic fields and gradually tend to high-frequency ultrasound applications. However, conventional continuous phase holograms are limited by three-dimensional(3D) printing size, and the presence of unavoidable small printing errors makes it difficult to achieve acoustic field reconstruction at high frequency accuracy. Here, we present an optimized discrete multi-step phase hologram. It can ensure the reconstruction quality of image with high robustness, and properly lower the requirement for the 3D printing accuracy. Meanwhile, the concept of reconstruction similarity is proposed to refine a measure of acoustic field quality. In addition, the realized complex acoustic field at 20 MHz promotes the application of acoustic holograms at high frequencies and provides a new way to generate high-fidelity acoustic fields.展开更多
Additives in the electrolytes of Li-S batteries aim to increase overall capacity,improve Li ion conductivity,enhance cyclability,and mitigate the shuttle effect,which is one of the major issues of this system.Here,the...Additives in the electrolytes of Li-S batteries aim to increase overall capacity,improve Li ion conductivity,enhance cyclability,and mitigate the shuttle effect,which is one of the major issues of this system.Here,the use of water as an additive in the commonly used electrolyte,1.0 M LiTFSI/1.0%(w/w) LiNO_(3) and a 1:1 mixture of 1,3-dioxolane(DOL) and 1,2-dimethoxyethane(DME) was investigated.We used Co_(2)Mn_(0.5)Al_(0.5)O_(4)(CMA) as an electrocatalyst anchored on an activated carbon(AC) electrode with added sulfur via a melt-diffusion process.The structural analysis of CMA via Rietveld refinement showed interatomic spaces that can promote ionic conductivity,facilitating Li^(+) ion migration.Electrochemical tests determined 1600 ppm as the optimal water concentration,significantly reducing the shuttle effect.Post-mortem XPS analysis focused on the lithium metal anode revealed the formation of Li_(2)O layers in dry samples and LiOH in wet samples.Better capacity was observed in wet samples,which can be attributed to the superior ionic conductivity of LiOH at the electrode/electrolyte interface,surpassing that of Li_(2)O by 12 times.Finally,Operando FTIR experiments provided real-time insights into electrolyte degradation and SEI formation,elucidating the activity mechanisms of water and Li_(2)CO_(3) over the cycles.This work presents results that could aid future advancements in Li-S battery technology,offering possibilities to mitigate its challenges with inexpensive and scalable additives.展开更多
Graphitized carbon foams(GFms)were prepared using mesophase pitch(MP)as a raw material by foaming(450℃),pre-oxidation(320℃),carbonization(1000℃)and graphitization(2800℃).The differences in structure and properties...Graphitized carbon foams(GFms)were prepared using mesophase pitch(MP)as a raw material by foaming(450℃),pre-oxidation(320℃),carbonization(1000℃)and graphitization(2800℃).The differences in structure and properties of GFms prepared from different MP precursors pretreated by ball milling or liquid phase extraction were investigated and compared,and semi-quantitative calculations were conducted on the Raman and FTIR spectra of samples at each preparation stage.Semi-quantitat-ive spectroscopic analysis provided detailed information on the structure and chemical composition changes of the MP and GFm de-rived from it.Combined with microscopic observations,the change from precursor to GFm was analyzed.The results showed that ball milling concentrated the distribution of aromatic molecules in the pitch,which contributed to uniform foaming to give a GFm with a uniform pore distribution and good properties.Liquid phase extraction helped remove light components while retaining large aromatics to form graphitic planes with the largest average size during post-treatment to produce a GFm with the highest degree of graphitization and the fewest open pores,giving the best compression resistance(2.47 MPa),the highest thermal conductivity(64.47 W/(m·K))and the lowest electrical resistance(13.02μΩ·m).Characterization combining semi-quantitative spectroscopic ana-lysis with microscopic observations allowed us to control the preparation of the MP-derived GFms.展开更多
With the modern advancement of treatment approaches in medical science, the application of biomaterials in tissue engineering provides a remarkable opportunity to overcome graft rejection as well as proper wound heali...With the modern advancement of treatment approaches in medical science, the application of biomaterials in tissue engineering provides a remarkable opportunity to overcome graft rejection as well as proper wound healing. In this study, novel hybrid films have been synthesized by incorporation of polyvinyl alcohol (PVA), gelatin, and gelatin with glycerin along with different concentrations of pre-prepared hydroxyapatite (HAP) by solution casting method at room temperature in a biosafety cabinet. Glutaraldehyde has been added as a crosslinker in this whole procedure. Fourier-transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD) have been conducted to observe and compare the structural and chemical stability of the synthesized hybrid film properties. The FTIR results and X-Ray Diffraction analyses confirmed the chemical interactions between HAP, PVA, gelatin, and glycerin have occurred. The crystallinity of HAP also remains in all the prepared hybrid film samples that are observed in XRD. It is expected that these newly synthesized hybrid films could be a better opportunity for various sectors of tissue engineering such as skin, bone, tendon, and cartilage. These synthesized hybrid films can be suitable for wound healing covering. These studies could be a new scope for long-term drug delivery directly on wound sites in diabetic gangrene foot or burn patients as well as cartilage or joint replacement therapy.展开更多
The Marplex Convention was established to prevent the manufacture of unmarked plastic explosives and stipulates that a volatile detection agent must be added at the time of manufacture.However,to-date,laboratory testi...The Marplex Convention was established to prevent the manufacture of unmarked plastic explosives and stipulates that a volatile detection agent must be added at the time of manufacture.However,to-date,laboratory testing remains the internationally accepted practice for identifying and quantifying the taggants stipulated in the Convention.In this project,portable FTIR and Raman instruments were tested for their ability to detect 2,3-dimethyl-2,3-dinitrobutane(DMDNB),the chemical marker incorporated in plastic explosives that are manufactured within Australia.While both FTIR and Raman instruments detected solid DMDNB(98%purity),field analysis of plastic explosives at an Australian Defence establishment showed that both FTIR and Raman spectra were matched the relevant explosive(RDX or PETN),rather than the DMDNB taggant.For all three plastic explosives tested,the concentration of DMDNB was measured by SPME-GC-MS to be between 1.8 and 2%,greater than the minimum 1%concentration stipulated by the Marplex Convention.Additional testing with a plastic explosive analogue confirmed that the minor absorption peaks that would characterize low concentrations of DMDNB were masked by absorption bands from other compounds within the solid.Thus,while both FTIR and Raman spectroscopy are suitable for detection of plastic explosives,neither rely on the presence of DMDNB for detection.It is likely that similar results would be found for other taggants stipulated by the Marplex Convention,given they are also present in concentrations less than 1%.展开更多
基金Project supported by the China Postdoctoral Science Foundation (Grant No.2023M732745)the National Natural Science Foundations of China (Grant Nos.61974110 and 62104177)+1 种基金the Fundamental Research Funds for the Central Universities,China (Grant Nos.QTZX23022 and JBF211103)the Cooperation Program of XDU– Chongqing IC Innovation Research Institute (Grant No.CQ IRI-2022CXY-Z07)。
文摘Acoustic holograms can recover wavefront stored acoustic field information and produce high-fidelity complex acoustic fields. Benefiting from the huge spatial information that traditional acoustic elements cannot match, acoustic holograms pursue the realization of high-resolution complex acoustic fields and gradually tend to high-frequency ultrasound applications. However, conventional continuous phase holograms are limited by three-dimensional(3D) printing size, and the presence of unavoidable small printing errors makes it difficult to achieve acoustic field reconstruction at high frequency accuracy. Here, we present an optimized discrete multi-step phase hologram. It can ensure the reconstruction quality of image with high robustness, and properly lower the requirement for the 3D printing accuracy. Meanwhile, the concept of reconstruction similarity is proposed to refine a measure of acoustic field quality. In addition, the realized complex acoustic field at 20 MHz promotes the application of acoustic holograms at high frequencies and provides a new way to generate high-fidelity acoustic fields.
基金the financial support from the Brazilian funding agencies FAPESP. (2024/01031-1, 2022/022220, 2020/04281-8, 21/14442-1, 17/11986-5)support from FAPESP through the research project Pi (2022/02901-4)+2 种基金CAPES (1740195)CNPq through the research grant (313672/2021-0)support Shell and the strategic importance of the support given by ANP (Brazil’s National Oil, Natural Gas and Biofuels Agency) through the R & D levy regulation。
文摘Additives in the electrolytes of Li-S batteries aim to increase overall capacity,improve Li ion conductivity,enhance cyclability,and mitigate the shuttle effect,which is one of the major issues of this system.Here,the use of water as an additive in the commonly used electrolyte,1.0 M LiTFSI/1.0%(w/w) LiNO_(3) and a 1:1 mixture of 1,3-dioxolane(DOL) and 1,2-dimethoxyethane(DME) was investigated.We used Co_(2)Mn_(0.5)Al_(0.5)O_(4)(CMA) as an electrocatalyst anchored on an activated carbon(AC) electrode with added sulfur via a melt-diffusion process.The structural analysis of CMA via Rietveld refinement showed interatomic spaces that can promote ionic conductivity,facilitating Li^(+) ion migration.Electrochemical tests determined 1600 ppm as the optimal water concentration,significantly reducing the shuttle effect.Post-mortem XPS analysis focused on the lithium metal anode revealed the formation of Li_(2)O layers in dry samples and LiOH in wet samples.Better capacity was observed in wet samples,which can be attributed to the superior ionic conductivity of LiOH at the electrode/electrolyte interface,surpassing that of Li_(2)O by 12 times.Finally,Operando FTIR experiments provided real-time insights into electrolyte degradation and SEI formation,elucidating the activity mechanisms of water and Li_(2)CO_(3) over the cycles.This work presents results that could aid future advancements in Li-S battery technology,offering possibilities to mitigate its challenges with inexpensive and scalable additives.
文摘Graphitized carbon foams(GFms)were prepared using mesophase pitch(MP)as a raw material by foaming(450℃),pre-oxidation(320℃),carbonization(1000℃)and graphitization(2800℃).The differences in structure and properties of GFms prepared from different MP precursors pretreated by ball milling or liquid phase extraction were investigated and compared,and semi-quantitative calculations were conducted on the Raman and FTIR spectra of samples at each preparation stage.Semi-quantitat-ive spectroscopic analysis provided detailed information on the structure and chemical composition changes of the MP and GFm de-rived from it.Combined with microscopic observations,the change from precursor to GFm was analyzed.The results showed that ball milling concentrated the distribution of aromatic molecules in the pitch,which contributed to uniform foaming to give a GFm with a uniform pore distribution and good properties.Liquid phase extraction helped remove light components while retaining large aromatics to form graphitic planes with the largest average size during post-treatment to produce a GFm with the highest degree of graphitization and the fewest open pores,giving the best compression resistance(2.47 MPa),the highest thermal conductivity(64.47 W/(m·K))and the lowest electrical resistance(13.02μΩ·m).Characterization combining semi-quantitative spectroscopic ana-lysis with microscopic observations allowed us to control the preparation of the MP-derived GFms.
文摘With the modern advancement of treatment approaches in medical science, the application of biomaterials in tissue engineering provides a remarkable opportunity to overcome graft rejection as well as proper wound healing. In this study, novel hybrid films have been synthesized by incorporation of polyvinyl alcohol (PVA), gelatin, and gelatin with glycerin along with different concentrations of pre-prepared hydroxyapatite (HAP) by solution casting method at room temperature in a biosafety cabinet. Glutaraldehyde has been added as a crosslinker in this whole procedure. Fourier-transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD) have been conducted to observe and compare the structural and chemical stability of the synthesized hybrid film properties. The FTIR results and X-Ray Diffraction analyses confirmed the chemical interactions between HAP, PVA, gelatin, and glycerin have occurred. The crystallinity of HAP also remains in all the prepared hybrid film samples that are observed in XRD. It is expected that these newly synthesized hybrid films could be a better opportunity for various sectors of tissue engineering such as skin, bone, tendon, and cartilage. These synthesized hybrid films can be suitable for wound healing covering. These studies could be a new scope for long-term drug delivery directly on wound sites in diabetic gangrene foot or burn patients as well as cartilage or joint replacement therapy.
基金funded by the Defence Science Technology Group(DSTG)。
文摘The Marplex Convention was established to prevent the manufacture of unmarked plastic explosives and stipulates that a volatile detection agent must be added at the time of manufacture.However,to-date,laboratory testing remains the internationally accepted practice for identifying and quantifying the taggants stipulated in the Convention.In this project,portable FTIR and Raman instruments were tested for their ability to detect 2,3-dimethyl-2,3-dinitrobutane(DMDNB),the chemical marker incorporated in plastic explosives that are manufactured within Australia.While both FTIR and Raman instruments detected solid DMDNB(98%purity),field analysis of plastic explosives at an Australian Defence establishment showed that both FTIR and Raman spectra were matched the relevant explosive(RDX or PETN),rather than the DMDNB taggant.For all three plastic explosives tested,the concentration of DMDNB was measured by SPME-GC-MS to be between 1.8 and 2%,greater than the minimum 1%concentration stipulated by the Marplex Convention.Additional testing with a plastic explosive analogue confirmed that the minor absorption peaks that would characterize low concentrations of DMDNB were masked by absorption bands from other compounds within the solid.Thus,while both FTIR and Raman spectroscopy are suitable for detection of plastic explosives,neither rely on the presence of DMDNB for detection.It is likely that similar results would be found for other taggants stipulated by the Marplex Convention,given they are also present in concentrations less than 1%.
