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We investigated the stability, ordering, and composition of mixed self-assembled monolayers (SAMs) on nanoporous gold surfaces formed by dealloying silver–gold leaf. We characterized surface featur...

Drop-casting is frequently used to deliver a sample for surface-enhanced Raman spectroscopy (SERS) and can result in inhomogeneous sample distribution during solvent evaporation. While soaking can provide better analyte homogeneity, it may require more sample than is available. Failure to optically sample analyte-rich substrate locations can compromise measurement outcomes. We developed and tested 3D printed SERS substrate holders that provided spatial registry of the dried sample droplet center for subsequent optical measurements. We found that deliberate and controlled spatial offsets (0–900 µm) between the analyte drop center and the laser excitation prevented signal intensity drops of as much as ∼3× and improved reproducibility. Thus, the use of offset-controlled 3D printed holders provided a quick and inexpensive way to improve the reliability of SERS measurements when using the convenient and popular choice of sample drop-casting.

Background subtraction is a general problem in spectroscopy often addressed with application-specific techniques, or methods that introduce a variety of implementation barriers such as having to specify peak-free regions of the spectrum. An iterative dual-tree complex wavelet transform-based background subtraction method (DTCWT-IA) was recently developed for the analysis of ultrafast electron diffraction patterns. The method was designed to require minimal user intervention, to support streamlined analysis of many diffraction patterns with complex overlapping peaks and time-varying backgrounds, and is implemented in an open-source computer program. We examined the performance of DTCWT-IA for the analysis of spectra acquired by a range of optical spectroscopies including ultraviolet–visible spectroscopy (UV–Vis), X-ray photoelectron spectroscopy (XPS), and surface-enhanced Raman spectroscopy (SERS). A key benefit of the method is that the user need not specify regions of the spectrum where no peaks are expected to occur. SER spectra were used to investigate the robustness of DTCWT-IA to signal-to-noise levels in the spectrum and to user operation, specifically to two of the algorithm parameter settings: decomposition level and iteration number. The single, general DTCWT-IA implementation performs well in comparison to the different conventional approaches to background subtraction for UV–Vis, XPS, and SERS, while requiring minimal input. The method thus holds the same potential for optical spectroscopy as for ultrafast electron diffraction, namely streamlined analysis of spectra with complex distributions of peaks and varying signal levels, thus supporting real-time spectral analysis or the analysis of data acquired from different sources.

Nanopores are nanofluidic channels formed through thin membranes that can deliver standout single-molecule and single-particle sensing capabilities. Analytical targets include small molecules and nanoparticles, and the DNA, protein, and glycan biopolymers underpinning genomics, proteomics, and glycomics. Detection—notably even in the simplest implementation, resistive-pulse sensing—does not inherently require sample labeling and, thus, offers the potential for general sensing utility combined with the prospective benefits of reduced sample processing requirements. A key pursuit for biopolymer sensing is the characterization of monomer sequence. This review article will provide an overview of the use of nanopores for general chemical sensing and –omics-related applications, writ-large. The broad analyte scope provides fertile ground for a discussion of principles governing nanopore sensing and considerations useful for guiding nanopore development. For nanopores to be effective in the face of broad analyte scope, stringent requirements on analytical performance must be met within the particular analyte class without sacrificing the operational flexibility necessary to be responsive across classes presenting very different physical and chemical challenges. These sample-driven challenges provide a unifying framework for discussing aspects of nanopore fabrication, properties, and integration; sensing paradigms, performance, and prospects; fundamental electrokinetic and interfacial phenomena; and practical challenges facing the use and further development of nanopore devices.

A nanopore can be fairly-but uncharitably-described as simply a nanofluidic channel through a thin membrane. Even this simple structural description holds utility and underpins a range of applications. Yet significant excitement for nanopore science is more readily ignited by the role of nanopores as enabling tools for biomedical science. Nanopore techniques offer single-molecule sensing without the need for chemical labelling, since in most nanopore implementations, matter is its own label through its size, charge, and chemical functionality. Nanopores have achieved considerable prominence for single-molecule DNA sequencing. The predominance of this application, though, can overshadow their established use for nanoparticle characterization and burgeoning use for protein analysis, among other application areas. Analyte scope continues to be expanded, and with increasing analyte complexity, success will increasingly hinge on control over nanopore surface chemistry to tune the nanopore, itself, and to moderate analyte transport. Carbohydrates are emerging as the latest high-profile target of nanopore science. Their tremendous chemical and structural complexity means that they challenge conventional chemical analysis methods and thus present a compelling target for unique nanopore characterization capabilities. Furthermore, they offer molecular diversity for probing nanopore operation and sensing mechanisms. This article thus focuses on two roles of chemistry in nanopore science: its use to provide exquisite control over nanopore performance, and how analyte properties can place stringent demands on nanopore chemistry. Expanding the horizons of nanopore science requires increasing consideration of the role of chemistry and increasing sophistication in the realm of chemical control over this nanoscale milieu.

Nanopores are a prominent enabling tool for single-molecule applications such as DNA sequencing, protein profiling, and glycomics, and the construction of ionic circuit elements. Silicon nitride (SiNx) is a leading scaffold for these

Polysaccharides have key biological functions and can be harnessed for therapeutic roles, such as the anticoagulant heparin. Their complexity—e.g., >100 monosaccharides with variety in linkage and branching structure—significantly complicates analysis compared to other biopolymers such as DNA and proteins. More, and improved, analysis tools have been called for, and here we demonstrate that solid-state silicon nitride nanopore sensors and tuned sensing conditions can be used to reliably detect native polysaccharides and enzymatic digestion products, differentiate between different polysaccharides in straightforward assays, provide new experimental insights into nanopore electrokinetics, and uncover polysaccharide properties. We show that nanopore sensing allows us to easily differentiate between a clinical heparin sample and one spiked with the contaminant that caused deaths in 2008 when its presence went undetected by conventional assays. The work reported here lays a foundation to further explore polysaccharide characterization and develop assays using thin-film solid-state nanopore sensors., The complexity of polysaccharides significantly complicates their analysis in comparison to other biopolymers. Here, the authors demonstrate that solid-state silicon nitride nanopore sensors can be used to reliably detect native polysaccharides and to perform a simple quality assurance assay on a polysaccharide therapeutic, heparin.

To evaluate the effects of cigarette smoking on some of the circulatory and ventilatory responses to exercise, a group of young male subjects, 18 smokers and 14 nonsmokers, was studied. Exercise consisted of a standard 5-min bicycle ergometer test that achieved a mean O2 uptake of 1.44 liters/ min in the 5th min of exercise. There was no difference between smokers and nonsmokers in the O2 uptake achieved during subsequent maximal exercise. Pulmonary function studies performed on the two groups revealed normal results for each group. There was an oxygen debt accumulation among smokers that was significantly greater ( P < 0.001) and this debt represented a greater per cent of the total O2 uptake. The heart rate at rest and 3 min after exercise in smokers was significantly faster ( P < 0.02). These differences do not appear to be related to ventilatory factors and may, therefore, be due to either circulatory or metabolic differences in the two groups. Submitted on August 17, 1962

1. 1. Fourteen infusions of potassium phosphate to 12 digitalized individuals with persistent ventricular ectopic rhythms resulted in a transient depression of the ectopic focus in 12 experiments. In one there was no effect and in another the ventricular premature beats increased in number during the infusion. In 4 additional patients the ventricular ectopic beats first appeared during or after the infusion. 2. 2. Depression of A-V conduction with resultant slowing of the ventricular rate was observed during 11 of the 18 infusions. 3. 3. The parallel depression of A-V conduction and the ectopic ventricular foci suggests that the effect of potassium is one of myocardial depression. Furthermore, the short-lived beneficial effect of potassium suggests that the mechanism may be due to a transient elevation of the extracellular level of the cation.

A case of atrial parasystole is reported. The parasystolic rhythm was intermittent in character and began each time with an atrial premature beat exhibiting a constant relation to the preceding sinus beat.

A case of dissociation within the A-V node with wandering of the upper nodal pacemaker and “double” nodal tachycardia is reported.

Excerpt The Family Nurse Practitioner Program at the Indiana University Schools of Medicine and Nursing is one of seven new programs designed to train registered nurses to assume greater responsibi...

Differences have been found in the cardiopulmonary responses to exercise between young male cigarette somkers and nonsmokers. The present study was undertaken in an attempt to determine the cause of such differences. Since smokers carry a chronically elevated carboxyhemoglobin level (>4%), carbon monoxide was inhaled by nonsmokers to raise their carboxyhemoglobin level to the range seen in a control group of smokers. This maneuver caused the development in nonsmokers of an increased oxygen debt with exercise and a reduced pulmonary diffusing capacity at rest. The changes after carbon monoxide inhalation were similar to those found when comparing smokers to nonsmokers. The pathogenesis of these changes are unknown, but support carbon monoxide as a possible etiologic factor accounting for the less efficient exercise and poorer pulmonary function performance of smokers compared to nonsmokers.