Dielectric Spectrometers with Planar Nanofluidic Channels

Disclosed is a method for fabricating nanofluidic channels having a height of from about 1 nm to about 10 nm. Generally, the method includes formation of doped silicon parallel strips in a silicon substrate, formation of a native oxide layer on the substrate, and etching of the native oxide layer at one of the strips to form a channel of a depth of between about 1 nm and about 10 nm. The method also includes bonding a second wafer to the surface, the second wafer including through etched windows to provide probe contacts to two of the parallel strips during use. These parallel strips provide high-frequency transmission lines in the device that can provide broadband dielectric spectroscopy measurement within the nanochannels

Integrated picosecond pulse generator circuit

A picosecond pulse generator apparatus and methodology is disclosed. A pulse generator is provided by forming a transmission line and a switching element on a common semiconductor substrate or semiconductor chip. The transmission line and the switching element can be provided on the common CMOS semiconductor substrate using standard CMOS technology. A voltage is applied to the transmission line to charge the transmission line. An input pulse is applied to the switching device to trigger the switching device to cause the transmission line to discharge an output pulse across a load resistor. The pulse width of the output pulse depends in major part on the length of the transmission line. Additional components can be provided on the common semiconductor substrate or chip to shape the input pulse to the switching device to ensure a fast rise time

Failure mechanism and practical load-carrying capacity calculation method of welded hollow spherical joints connected with circular steel tubes

p. 2679-2691According to the ultimate load-carrying capacity obtained from finite element analysis, data point is designed based on orthogonal method, utilizing F-inspection from mathematical statistics to perform multi-parameter and single-factor significance analysis of compressive load capacity. The result indicates that yield strength of spherical material fy are the critical factor that influence the load carrying capacity of hollow spherical joint, as well as wall thickness t, outer diameter of sphere D and outer diameter of steel tube d. Comparatively destructive experiments on 8 typical full-scale joints made from two different graded material, Q235B and Q345B, were conducted to understand directly the structural behavior and the collapse mechanism of the joint, and also to validate the finite element analysis and parameter study. Finally, the simplified theoretical solution is also derived for the loading-carrying capacity of the joint based on the punching shear failure model, and the basic form for the design equation is obtained. By applying the results from the simplified theoretical solution, finite element analysis and experimental study, and utilizing the theory of mathematic statistics and regression analysis, the practical calculation method is established for the load-carrying capacity of the joints subjected to axial compressive forces. By the check of large amount of experiment data, the calculation result obtained from this formula is consistent with experiment result, and the practical formula has safety reserve meeting the regulation in national codes. The achievements from this study can be applied for direct design , and also provide a reference for the revision of relevant design codes.Xue, W.; Yang, L.; Zhang, Q.; Wang, P. (2009). Failure mechanism and practical load-carrying capacity calculation method of welded hollow spherical joints connected with circular steel tubes. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/660

High Sensitivity Tunable Radio Frequency Sensors

Highly sensitive and tunable RF sensors that provide detection and analysis of single cells and particles are provided. The tunable RF sensors are configured as tunable interferometers, wherein cells or particles to be analyzed are passed through a channel, such as a microfluidic channel, across waveguides corresponding to reference and test branches of the interferometers. A network analyzer coupled to the interferometers can be configured to measure a plurality of scattering parameters, such as transmission scattering coefficients (S.sub.21) of the reference and test branches, to evaluate characteristics of cells passing through the channel. A plurality of tunable interferometers may be employed, each interferometer operating in different frequency bands such that information obtain from the plurality of interferometers may be combined to provide further information

Microwave Dielectric Properties of On-Chip Liquid Films

A microwave characterization method for on-chip liquid film dielectric property measurement is developed. Microstrip-line based on-chip test structures are fabricated to characterize the microwave dielectric properties of various on-chip liquid films: DI water and binary mixtures of DI water with glucose and ethanol. The obtained microwave dielectric properties are presented in Cole-Cole diagrams, which show general frequency dependence similar to that of bulk liquids. Different concentration levels of glucose and ethanol show different microwave dielectric responses. Therefore, on-chip microwave dielectric spectroscopy provides a promising and inexpensive on-chip sensing mechanism for biomedical and chemical applications

Architecture of Heptagonal Metallo-macrocycles via Embedding Metal Nodes Into Its Rigid Backbone

Metal-organic macrocycles have received increasing attention not only due to their versatile applications such as molecular recognition, compounds encapsulation, anti-bacteria and others, but also for their important role in the study of structure-property relationship at nano scale. However, most of the constructions utilize benzene ring as the backbone, which restricts the ligand arm angle in the range of 60, 120 and 180 degrees. Thus, the topologies of most metallo-macrocycles are limited as triangles and hexagons, and explorations of using other backbones with large angles and the construction of metallo-macrocycles with more than six edges are very rare. In this study, we present a novel strategy for self-assembly two giant heptagonal metallo-macrocycles with an inner diameter of 5 nm, by embedding metal nodes into the ligand backbone and regulating the ligand arm angle. By complexing with metal ions, the angle between two arms at the 4,4” position of the central terpyridine (tpy) was extended, resulting in ring expansion of the metallo-macrocycle. This approach enabled the construction of giant and more complex metallo- macrocycles that could not be achieved with traditional benzene ring backbones. The characterization of complex molecules often requires the use of multiple techniques, such as multi-dimensional and multinuclear NMR and multidimensional mass spectrometry analysis. Here, we also utilized transmission electron microscopy (TEM) and ultra-high vacuum (∼E-10 torr) low-temperature (∼77 K) scanning tunneling microscopy (UHV-LT-STM) to characterize complex supramolecules. The resulting metallo-macrocycles formed hierarchical self-assembled nanotube structures at larger densities, which is observed by TEM, while UHV-LT-STM was used for direct visualization of individual complex supramolecules deposited on an Au(111) substrate. Our findings indicate that UHV-LT-STM is an effective methodology for characterizing supramolecules at a single molecule level, providing more details of the molecular structure that is difficult to resolve by the resolution of TEM.https://digitalcommons.odu.edu/gradposters2023_sciences/1005/thumbnail.jp