模拟3种有机膦系阻垢剂与方解石(104)面的相互作用

通过pH曲线实验研究了乙二胺四亚甲基膦酸(EDTMP),己二胺四亚甲基膦酸(HDTMP)和二乙烯三胺五亚甲基膦酸(DTPMP)对碳酸钙垢的阻垢性能,在相同的加药浓度下阻垢性能强弱顺序为:DTPMPEDTMPHDTPM。同时采用周期性边界条件下的分子动力学方法,模拟研究了在水分子存在条件下各阻垢剂与方解石(104)面的相互作用,得到了相应的结合能和原子间距离等参数。结果表明:阻垢分子膦酸基团中的双键氧与碳酸钙中的Ca~(2+)形成的强静电相互作用力对吸附起了主导作用,同时膦酸基团中的氢与晶面中的氧形成了氢键,加强了吸附效果。综合考虑各分子在晶面(104)上的吸附效果,其结果与实验相符合;从分子中膦酸基团作用个数也可看出,HDTMP只有一个膦酸基团靠近晶面,因此作用力也是最弱的。     

Improving the initialization speed for long-range NRTK in network solution mode

Initialization speed is one of the most important factors in network real time kinematic (NRTK) performance. Owing to the low correlation among the error s     

提高镇三增输油离心泵保养合格率

针对离心泵故障高的原因寻找方法,通过对操作人员的培训及细化管理,提高了离心泵的保养合格率,降低了故障停机率。     

Effect of different initiators on temperature-sensitive monolithic columns and application in online enrichment of β-sitosterol

Three temperature-sensitive monolithic columns were prepared by atom transfer radical polymerization and oxidation–reduction method using the initiator systems of CCl₄/FeCl₂, BPO/DMA, and APS/TEMED, respectively. The three monoliths were characterized by scanning electron microscopy, nitrogen adsorption, and thermogravimetric analysis. The obtained monolithic columns were used as on-line solid phase extraction sorbent coupled with high-performance liquid chromatography for the enrichment of β-sitosterol. By comparing some influencing factors on the adsorption, the optimum temperature-sensitive monolithic column which was initiated by CCl₄/FeCl₂ was selected for enrichment of β-sitosterol from plant oil. The maximum adsorption capacity of the monolith for β-sitosterol was 10.0031 mg/g. The limit of detection and limit of quantitation were 0.039 and 0.13 mg/mL, respectively. The recovery was in the range of 90.21–98.26%. The results showed that the monolith had better selectivity for β-sitosterol and could be used for enrichment of β-sitosterol in food samples. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47683.     

Functional chemical modification of a porcine acellular dermal matrix with a modified naturally derived polysaccharide crosslinker

Antibacterial and physicochemical properties are generally considered important features of the porcine acellular dermal matrix (pADM). Oxidized 2-hydroxypropyltrimethyl ammonium chloride chitosan (OHTCC) was applied to crosslink with pADM at dosages of 1, 2, 4, 8, and 16%. The properties of the crosslinked pADM (OHTCC-pADM) were evaluated. DSC and TG analysis suggested that crosslinking could promote the thermal stability, the highest T_d, and T_max of OHTCC-pADM (8%) was 80 °C and 325 °C, which has been improved by 15 °C and 13 °C, respectively. While FTIR and AFM tests indicated that the structure integrity of collagen could still be maintained. SEM tests demonstrated the sustained three-dimensional architecture of OHTCC-pADM with appropriate porosity. Moreover, OHTCC-pADM exhibited improved ability to resist collagenase degradation, the degradation rate of 4%-, 8%-OHTCC-pADM was <50%. The tensile strength of OHTCC-pADM proved to be superior compared to pADM. Furthermore, 8%-OHTCC-pADM exhibited nearly 90% antibacterial activity against Escherichia coli, and Staphylococcus aureus. In addition, the results of the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazoliumbromide study showed that the cytocompatibility of OHTCC-pADM decreased with the increasing the amount of OHTCC, but all relative proliferation rates were above 80%. In conclusion, our study revealed that OHTCC stabilized and functionalized pADM while preserving good cytocompatibility. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47633.     

Property of Self-Similarity Between Baseband and Modulated Signals

Mobile Networks and Applications - The increment of communication technologies and the&nbsp;development of signal processing require efficient identification techniques for communication...     

多层圆片级堆叠THz硅微波导结构的制作

基于微电子机械系统(MEMS)工艺,提出一种多层圆片堆叠的THz硅微波导结构及其制作方法。为了验证该结构在制作THz无源器件中的优势,基于6层圆片堆叠的硅微波导结构,设计了一种中心频率365 GHz、带宽80 GHz的功率分配/合成结构,并对其进行了仿真。研究了制作该结构的工艺流程,攻克了工艺过程中的关键技术,包括硅深槽刻蚀技术和多层热压键合技术,并给出了工艺结果。最终实现了多层圆片堆叠功率分配/合成结构的工艺制作和测试。测试结果表明,尽管样品的插入损耗较仿真值增加3 dB左右,考虑到加工误差和夹具损耗等情况,样品主要技术指标与设计值较为一致。