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1.
X-ray emission for Ar11+ ions impacting on various targets in the collisions near the Bohr velocity 下载免费PDF全文
Xian-Ming Zhou 《中国物理 B》2021,30(8):83201-083201
X-ray emission from the collisions of 3 MeV Ar11+ ions with V, Fe, Co, Ni, Cu, and Zn is investigated. Both the x-rays of the target atom and projectile are observed simultaneously. The x-ray yield is extracted from the original count. The inner-shell ionization cross section is estimated by the binary encounter approximation model and compared with the experimental result. The remarkable result is that the Ar K-shell x-ray yield is diminished with the target atomic number increasing, which is completely opposite to the theoretical calculation. That is interpreted by the competitive consumption of the energy loss for the ionization of inner-shell electrons between the projectile and target atom. 相似文献
2.
将一种人工合成的无机聚合物——蒙脱石皂石黏土(smectite,Sm)应用于基质辅助激光解吸电离飞行时间质谱分析(matrix-assisted laser desorption/ionization time of flight mass spectrometry, MALDI-TOF-MS),以检测糖类化合物。 将传统的有机基质2,4,6-三羟基苯乙酮(trihydroxyacetophenone, THAP)与阳离子交换后的皂石黏土混合制备成新型复合基质,应用于糖类化合物的检测。通过比较不同的制样方法,测定不同分子直径的糖类化合物,发现由于受复合基质晶面间距的限制,只有小分子糖类化合物能进入晶面间隙充分接触有机基质并被离子化,从而实现对小分子糖类化合物的选择性检测。 相似文献
3.
利用ANSYS 对低活化铁素体马氏体(RAFM)钢进行非熔化极气体保护焊(TIG 焊)与电子束焊的抗疲劳模拟分析,再利用SDS200 电液伺服疲劳试验机对TIG 焊和电子束焊的两种RAFM 钢试件进行实验。通过施加相同梯度负荷对TIG 焊和电子束焊试件进行焊缝的疲劳性能实验。与实验结果对比分析,结果显示电子束焊优于 TIG 焊,但在一定负载下可以用TIG 焊代替电子束焊。 相似文献
4.
随着化石能源的日益短缺,可再生木质生物质资源的利用越来越受到重视,常压液化技术是生物质资源高效利用的主要方式之一。利用单因素方法,探讨液化温度、复配液化剂二甘醇(DEG)与1,2-丙二醇(PG)的混合比、液固比、催化剂磷酸的用量、反应时间等因素对玉米秸秆液化得率的影响,以便优化其液化工艺;然后采用热重分析仪(TGA)、气相色谱-质谱技术(GC-MS)和核磁共振(NMR)技术对此优化条件下所得生物油的挥发降解特性和主要组成成分进行了检测探讨。分析表明,玉米秸秆液化时优化工艺参数为:液化温度170 ℃,液化剂DEG与PG混合比1∶2,液固比5∶1,H3PO4用量10%,反应时间45 min;此时玉米秸秆液化得率高至99.50%。TGA结果表明,此条件下所得生物油含有80%以上碳数小于25的化合物,热解后最终残炭量约为15%。GC-MS表明,可以检测出此生物油中含有的39种有机物,其中,醇类有机物的含量最多,酚类有机物的含量次之,它们相对含量依次是70.70%和25.63%,其还含有一定量的有机酸(2.80%)、醚类(0.64%)、酯类(0.10%)和酮类(0.13%)等有机物;其组分十分复杂,高含氧量,稳定性较差。1H-和13C-NMR分析表明,不同化学位移δ与生物油中不同类型的质子和碳原子相对应,明确生物油中不同类型H和C的分布,有利于对其分子结构进行深入探讨。这些研究为非木材生物质高效液化条件的选择及液化产物制备化学品和生物燃油给予理论基础与应用支持,促进了生物质资源的有效转化利用及其生物质基产品的开发。 相似文献
5.
为探索油-气-水三相流持气率测量难题,该文开展了脉冲透射式超声传感器持气率测量动态实验研究。首先,利用超声传感器与光纤传感器组合,测取了油-气-水三相流中段塞流、混状流、泡状流的响应信号;其次,提取了超声脉冲信号的最大值序列来反映不同流型时超声传感器响应特性,同时,借助双头光纤传感器与相关测速法,计算得到了流体中气泡弦长序列;最后,结合流型与泡径信息,利用超声传感器测量了不同流型下持气率,并分析了不同流型持气率预测的误差来源,为其他油-气-水三相流持气率测量传感器设计提供了借鉴。 相似文献
6.
Recent research has focused on increasing the evidentiary value of latent fingerprints through chemical analysis. Although researchers have optimized the use of organic and metal matrices for matrix‐assisted laser desorption/ionization‐mass spectrometry imaging (MALDI‐MSI) of latent fingerprints, the use of development powders as matrices has not been fully investigated. Carbon forensic powder (CFP), a common nonporous development technique, was shown to be an efficient one‐step matrix; however, a high‐resolution mass spectrometer was required in the low mass range due to carbon clusters. Titanium oxide (TiO2) is another commonly used development powder, especially for dark nonporous surfaces. Here, forensic TiO2 powder is utilized as a single‐step development and matrix technique for chemical imaging of latent fingerprints without the requirement of a high‐resolution mass spectrometer. All studied compounds were successfully detected when TiO2 was used as the matrix in positive mode, although, generally, the overall ion signals were lower than the previously studied CFP. TiO2 provided quality mass spectrometry (MS) images of endogenous and exogenous latent fingerprint compounds. The subsequent addition of traditional matrices on top of the TiO2 powder was ineffective for universal detection of latent fingerprint compounds. Forensic TiO2 development powder works as an efficient single‐step development and matrix technique for MALDI‐MSI analysis of latent fingerprints in positive mode and does not require a high‐resolution mass spectrometer for analysis. 相似文献
7.
8.
《中国化学快报》2020,31(8):2155-2158
Detection of trace-level hydrogen sulfide (H2S) gas is of great importance whether in industrial production or disease diagnosis. This research presents a novel H2S gas sensor based on integrated resonant dual-microcantilevers which can identify and detect trace-level H2S in real-time. The sensor consists of two integrated resonant microcantilever sensors with different functions. One cantilever sensor can identify H2S by outputting positive frequency shift signals, while the other cantilever sensor will detect H2S as a normally used cantilever sensor with negative frequency shifts. Combined the two cantilever sensors, the proposed gas sensor can distinguish H2S from a variety of common gases, and the detection limit to H2S of the sensor is as sensitive as below 1 ppb. 相似文献
9.
TiO2-based photocatalysis has become a viable technology in various application fields such as (waste)water purification, photovoltaics/artificial photosynthesis, environmentally friendly organic synthesis and remediation of air pollution. Because of the increasing impact of bad air quality worldwide, this review focuses on the use and optimization of TiO2-based photocatalysts for gas phase applications. Over the past years various specific aspects of TiO2 photocatalysis have been reviewed individually. The intent of this review is to offer a broad tutorial on (recent) trends in TiO2 photocatalyst modification for the intensification of photocatalytic air treatment. After briefly introducing the fundamentals of photocatalysis, TiO2 photocatalyst modification is discussed both on a morphological and an electronic level from the perspective of gas phase applications. The main focus is laid on recent developments, but also possible opportunities to the field. This review is intended as a solid introduction for researchers new to the field, as well as a summarizing update for established investigators. 相似文献
10.
Thin film composite (TFC) reverse osmosis (RO) membranes are semipermeable membranes that are utilized in water purification or water desalination systems. Discarding these membranes after end-of-life leads to environmental problems. Reusing old TFC-RO membranes is one way to solve this problem. For this reason, in this study, used TFC-RO membranes were coated with polydimethylsiloxane (PDMS) for CO2/N2 gas separation application. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was utilized to confirm the crosslinking of coated PDMS. The morphology of PDMS/TFC-RO membranes was characterized using scanning electron microscopy (SEM). The parameters that can affect performance of prepared membranes (N2 permeance and CO2/N2 selectivity) are concentration of PDMS solution, coating time, solvent evaporation time and curing temperature and time. Given that the used membranes don't have uniform surfaces, the first step of this study was to investigate the effect of the above mentioned factors on virgin membranes using fractional factorial design (FFD) of experiments. The results obtained showed that PDMS concentration is the most significant factor that has a negative effect on N2 permeance and positive effect on CO2/N2 selectivity. The reported CO2/N2 selectivity of PDMS membranes was 11–12, but this selectivity for prepared PDMS/TFC-RO membranes was in the range of 6.7–22.5. After determining optimum conditions, the gas separation performance of PDMS coated used TFC-RO membrane under these conditions was finally determined. The results showed that the used membranes had a better performance than virgin membranes. 相似文献