Simple isotopic product rules valid for absolute and integrated infrared intensities

Microwave spectra of CH¹⁸ OCOOH, CHOC¹⁸ OOH, CHOCO¹⁸ OH, ¹³ CHOCOOH and CHO¹³ COOH are reported and have been used in combination with data on CHOCOOH and CHOCOOD to determine the molecular structure as r(C=O)_ald. = 1.174 ± 0.006 Å, r(C=O)_acid = 1.203 ±0.006 Å, r(C—O) = 1.313 ± 0.010 Å, r(C—C) = 1.535 ± 0.005 Å, r(O—H) = 0.948 ± 0.004 Å, r(C—H) = 1.104 ±0.010 Å, ald. = 123.7 ± 0.4<, 相似文献   

Quaterthiophene-based dimers containing an ethylene bridge: molecular design,synthesis, and optoelectronic properties

Two quaterthiophene-based dimers including an ethylene bridge have been designed and efficiently prepared; experimental and computational studies show a promising potential as semiconducting material with a charge transport of higher dimensionality compared to quaterthiophene.     

混合硅激光工艺带来了先进的光子芯片

采用标准的硅加工工艺,Intel公司和加州大学的研究人员开发出了一种新技术。该技术能在单芯片中结合磷化铟的光发射能力和硅的光路由能力,从而产生一个全新的混合硅激光器。为了能扩展对光子的应用,这项技术着重解决了生产低成本、高带宽的光电子器件的主要障碍。基于可用在晶圆、部分晶圆和模级别的结合方法,该技术能使磷化铟中的发光原型融入硅波导管中,从而产生能驱动其他硅光子器件的连续激光束。整个工艺使用了低温氧等离子体来在所有材料上创建一个相当于25个原子厚的氧化层。     

Periodic schedules for linear precedence constraints

We consider the computation of periodic cyclic schedules for linear precedence constraints graphs: a linear precedence constraint is defined between two tasks and induces an infinite set of usual precedence constraints between their executions such that the difference of iterations is a linear function. The objective function is the minimization of the maximal period of a task.We recall first that this problem may be modelled using linear programming. A polynomial algorithm is then developed to solve it for a particular class of linear precedence graphs called unitary graphs. We also show that a periodic schedule may not exist for unitary graphs. In the general case, a decomposition of the linear precedence graph into unitary components is computed and we assume that a periodic schedule exists for each of these components. Lower bounds on the periods are exhibited and we show that an optimal periodic schedule may not achieve them. The notion of quasi-periodic schedule is then introduced and we prove that this new class of schedules always reaches these bounds.     

Microfluidic multi-analyte gradient generator

A microfluidic device was developed to produce temporal concentration gradients of multiple analytes. Four on-chip pumps delivered pulses of three analytes and buffer to a 14-cm channel where the pulses were mixed to homogeneity. The final concentration of each analyte was dependent on the temporal density of the pulses from each pump. The concentration of each analyte was varied by changing the number of pump cycles from each reservoir while maintaining the total number of pump cycles per unit time to ensure a constant total flow rate in the device. To gauge the independent nature of each pump, sinusoidal waves of fluorescein concentration were produced from each pump with independent frequencies and amplitudes. The resulting fluorescence intensity was compared with a theoretical summation of the waves and the experimental data matched the theoretical waves within 1%, indicating that the pumps were operating independently and outputting the correct frequency and amplitude. The device was used to demonstrate the role of adenosine triphosphate-sensitive K⁺ channels in glucose-stimulated increases in intracellular [Ca²⁺] in islets of Langerhans. Perfusion of single islets of Langerhans with combinations of glucose, diazoxide, and K⁺ resulted in intracellular Ca²⁺ patterns similar to what has been observed using conventional perfusion devices. The system will be useful in other studies with islets of Langerhans, as well as other assays that require the modulation of multiple analytes in time.     

From calcium interaction to calcium electrochemical detection by [(C5H5)Fe(C5H4COCH=CHC6H4NEt2)] and its two novel structurally characterized derivatives

[(C(5)H(5))Fe(C(5)H(4)COCH=CHC(6)H(4)NEt(2))] (1) has been electrochemically evaluated toward different cations in solution. Calcium sensing by this compound and its two new derivatives [(C(5)H(5))Fe(C(5)H(4)CO(CH=CH)(2)C(6)H(4)NMe(2))] (2) and [(C(5)H(5))Fe(C(5)H(4)CH=CHCOCH=CHC(6)H(4)NEt(2))] (3) that exhibit a conjugated link between the ferrocene unit and the nitrogen atom has been thoroughly examined. Compounds 2 and 3 have been structurally characterized by single-crystal X-ray diffraction studies. The three related protonated species [1H][BF(4)] (4), [2H][BF(4)] (5), and [3H][BF(4)] (6) have been isolated in a good yield. NMR experiments clearly established that calcium interaction occurs in the vicinity of the carbonyl group, and mass spectrometry studies confirmed that this interaction, which involves several ligand-Ca(2+) adducts, is complex. A combination of electrochemical and NMR experiments highlighted an original salt influence on the electrochemical calcium sensing result.     

Reverse phase thin-layer chromatographic separation of bromodiphenhydramine and diphenhydramine.

A thin-layer chromatographic system is described for the separation of diphenhydramine and bromodiphenhydramine which is based on a reverse phase paper chromatographic system developed by J. Vecerková (2,3) in 1962. Chromatographic systems for this separation described in the literature and several systems attempted in this laboratory using normal chromatography have not proven successful. The method using reverse phase thin-layer chromatography involves a stationary phase of mineral oil on silica gel G and a mobile phase of ethanol:water:ammonium hydroxide, 28% NH3, (55:43:2). A 10-cm length of run requires about three hours and provides an excellent separation of the two compounds for identification-differentiation purposes.     

General theoretical study of the stepwise coupling methods:: Part I. Determination of the generalised valence force field in the n-order cases and the matrix polynomial expansion of the eigenvector method

In the n-order general cases the Eigenvector Method of Becher and Mattes is shown to have an equivalent form: The Matrix Polynomial Expansion Method which is much simpler for computational procedures and has none of the inconvenience of the previous stepwise coupling methods (e.g., the Fadini's methods, the Eigenvector Method and the Logarithmic Steps Method of Wendling and Mahmoudi). It is also shown that the Eigenvector Method and the Matrix Polynomial Expansion Method correspond to the “closest solution” to the complete uncoupled initial solution, thereby justifying the method and giving application limits.