基于iPLS的血清胆固醇、甘油三酯近红外定量分析

为了建立血清样品胆固醇、甘油三酯近红外分析最优模型,利用近红外透射光谱技术结合间隔偏最小二乘法（iPLS）建立预测模型。结果表明,胆固醇最优建模波段是1700—1798nm,最优预测模型的相关系数Rp、预测均方差RMSEP分别为0.984、0.198mmol/L;甘油三酯最优建模波段是1654-1746nm,最优预测模型的Rp、RMSEP分别为0.967、0.157mmol/L。采用iPLS建立血清胆固醇、甘油三酯定量分析模型,不仅可以提高模型的预测精度,而且模型更加简洁、数据运算量也更少,优选出的特征谱区还可为设计小型专用近红外分析仪器提供依据。     

光声光谱技术在多组分气体浓度探测中的应用

CO和CH_4气体作为判断变压器运行状态的故障气体,对其浓度的探测在变压器维护中具有重要意义.为了准确探测变压器运行过程中产生的CH_4和CO气体浓度,本文利用光声光谱技术,设计了一套基于宽带光源的多组分气体探测系统,和共振型光声系统相比,该系统中所用的非共振型光声池体积小,易加工,池内各处信号强度相同,降低了对声学信号探测器的安装要求.系统的性能通过对CO和CH_4气体的探测进行评估.首先,从理论上分析了信号强度与调制频率呈反比,然后根据宽带光声系统在不同调制频率下的响应,确定系统的最佳调制频率为22 Hz.在最佳调制频率下,根据温度与待测气体光声信号的关系,对光声信号进行温度补偿,消除温度变化对光声信号的影响,进一步提高了系统的稳定性.最后,通过不同浓度的CH_4和CO气体对系统进行标定.实验表明,温度补偿前后,光声信号随温度的漂移分别为0.023 23V/℃和8.383 48×10~(-5) V/℃,通过对不同浓度CH_4和CO气体的探测,系统的线性度分别达到0.995和0.998 4.在一个大气压下,积分时间为1s时,宽带光声探测系统对CO和CH_4气体的探测极限浓度能够达到1μL/L.该系统成本低,线性度好,探测灵敏度符合国标对变压器维护过程中CO和CH_4气体的探测要求.     

二维表面浮雕结构的矢量衍射分析

利用等效介质理论,通过严格的耦合波理论计算和分析了二维表面浮雕结构的反射效率与各种因素的关系,给出了不同情况下的变化曲线;同时计算出了该结构在正入射情况下的等效折射率系数。明确提出：不管是对称的还是非对称的二维表面浮雕结构,方位角和极化角的变化对其反射率的影响都不明显;从而得出二维表了雕结构可以实现消偏振、减反的特性。分析了该结构的带宽限制,给出了在给定结构下受限的带宽;同时对浮雕高度加工误差对反射率的影响作了分析,对实际工作有一定的指导意义。     

Spectroscopic Studies of the Stability of Doped Polythiophenes Under Air

Abstract

The stability of the doped state of conductive polythiophenes under air was investigated by the use of Infrared (IR) and UV-visible (UV) spectroscopies. Poly(3-methyl thiophene) doped with BF₃-ethyl ether (BFEE). shows higher stability due to its stereoregularity-chain structure. While the doped polythiophene (PT) degrades easily under the moisture.     

基于硒化锌薄膜法的食源性致病菌原位红外光谱检测

食源性致病菌是引发和威胁公众健康的主要因素之一.由于食源性致病菌种类繁多,常规检测方法复杂耗时要求高,因此迫切需要一种更加快速精确的致病菌检测技术.在传统红外光谱检测致病菌的流程中,如经典的溴化钾压片法,除了压片本身的操作之外通常还需对样品进行冷冻干燥(约需2 d)等耗时前处理过程,因而不利于高通量快速检测.本研究利用...     

Real-time quantification of Staphylococcusaureus in liquid medium using infrared thermography

We previously showed that infrared thermography (IRT) could be used to quantify viable Escherichiacoli, a representative gram-negative bacterium, in liquid growth media. Here, we evaluated the ability of IRT to enumerate a viable representative gram-positive organism, Staphylococcusaureus. We found that the energy content (EC) of the media was strongly positively correlated (r = 0.999) to measured viable counts of S.aureus ranging from 85 colony-forming units (CFU)/ml to ∼4 × 10⁸ CFU/ml. The EC of S.aureus was ∼2-fold higher than that of E.coli at comparable cell concentrations suggesting that IRT may be used to distinguish genera.     

Preparation of a novel infrared low-emissive coating from the Cu powder modified by the polyethylene wax

Cu powder was coated with polyethylene wax via the flux-capping method in hope to avoid the oxidation of it, so the increment of the infrared emissivity of the coating can be greatly reduced. The prepared product was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The infrared emissivity of the prepared material was measured by Infrared Emissometer. The influence parameters that will affect the emissivity of the coating were systematically investigated, such as the content of coated Cu powder, coating fineness, coating thickness and aging process. The results indicated that the infrared emissivity value of the coating was reduced after Cu powder was coated with polyethylene wax. The polyethylene wax/Cu composites presented a homogenous sheet structure when the content of Cu powder increased to 30 wt.%, and it has a lower emissivity. The infrared emissivity of the coating increases rapidly as thickness increases and becomes steady above thickness of 70 μm. The composite coating exhibits lower emissivity value and excellent physical properties at coated Cu content of 20 wt.%. The emissivity of the coating that was prepared from the modification of the Cu powder was decreased with the decrement of the grinding fineness and increased with the aging time. The emissivity of the coating that was prepared from the modification of the Cu powder is always lower than that of the coating that only composed of the Cu powder with the increment of the aging time. Therefore, it can be concluded that the anti-oxidation of Cu powder is greatly improved after it was modified by polyethylene wax, which results in a novel coating with long-run low emissivity.     

Analysis of Urinary Calculi Containing Triamterene. Presence of A Glucuronic Metabolite.

Abstract

Urinary calculi containing triamterene were described since 1979. We have studied calculi, obtained from an anuric patient, by surgery. This paper describes the advanced techniques that were used, such as infrared spectroscopy, nuclear magnetic resonance, mass spectrometry associated with thin-layer chromatography or gas chromatography, to show the presence of unusual compounds. Six metabolites are found, among them pure triamterene (96%), hydroxy-triamterene, and a particular metabolite containing glucuronic acid.     

Probing defect species on real surfaces from the analysis of the spectral profile of admolecules

The analysis of changes in the vibrational spectrum of infrared active molecules adsorbed on a ionic surface containing point or extended defects can be an efficient method to determine the nature and density of surface defects. We study the infrared response of ammonia molecules deposited on a ionic surface of MgO containing charge vacancies and dipolar defects in various concentrations and distributions and show significant changes assigned to the defects signature. A Monte Carlo approach is used to randomly deposit the probe molecules on the surface displaying random or regularly arranged defects at low temperature.