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Recent calls for improvement in undergraduate education within STEM (science, technology, engineering, and mathematics) disciplines are hampered by the methods used to evaluate teaching effectiveness. Faculty members at research universities are commonly assessed and promoted mainly on the basis of research success. To improve the quality of undergraduate teaching across all disciplines, not only STEM fields, requires creating an environment wherein continuous improvement of teaching is valued, assessed, and rewarded at various stages of a faculty member's career. This requires consistent application of policies that reflect well-established best practices for evaluating teaching at the department, college, and university levels. Evidence shows most teaching evaluation practices do not reflect stated policies, even when the policies specifically espouse teaching as a value. Thus, alignment of practice to policy is a major barrier to establishing a culture in which teaching is valued. Situated in the context of current national efforts to improve undergraduate STEM education, including the Association of American Universities Undergraduate STEM Education Initiative, this essay discusses four guiding principles for aligning practice with stated priorities in formal policies: 1) enhancing the role of deans and chairs; 2) effectively using the hiring process; 3) improving communication; and 4) improving the understanding of teaching as a scholarly activity. In addition, three specific examples of efforts to improve the practice of evaluating teaching are presented as examples: 1) Three Bucket Model of merit review at the University of California, Irvine; (2) Evaluation of Teaching Rubric, University of Kansas; and (3) Teaching Quality Framework, University of Colorado, Boulder. These examples provide flexible criteria to holistically evaluate and improve the quality of teaching across the diverse institutions comprising modern higher education.

Surface enhanced Raman scattering (SERS) provides a label free method of analyzing molecules from diverse and complex signals, potentially with single molecule sensitivity. The chemical specificity inherent in the SERS spectrum can identify molecules; however signal variability arising from the diversity of plasmonic environments can limit quantification, particularly at low concentrations. Here we show that digitizing, or counting SERS events, can decrease the limit of detection in flowing solutions enabling quantification of single molecules. By using multivariate curve resolution and establishing a score threshold, each individual spectrum can be classified as containing an event or not. This binary "yes/no" can then be quantified, and a linear region can be established. This method was shown to lower the limit of detection to the lowest physical limit, and lowered the limit of detection by an order of magnitude from the traditional, intensity based LOD calculations. [ABSTRACT FROM AUTHOR]

Fibromyalgia (FM) is a chronic central sensitivity syndrome characterized by augmented pain processing at diffuse body sites and presents as a multimorbid clinical condition. Long COVID (LC) is a heterogenous clinical syndrome that affects 10–20% of individuals following COVID-19 infection. FM and LC share similarities with regard to the pain and other clinical symptoms experienced, thereby posing a challenge for accurate diagnosis. This research explores the feasibility of using surface-enhanced Raman spectroscopy (SERS) combined with soft independent modelling of class analogies (SIMCAs) to develop classification models differentiating LC and FM. Venous blood samples were collected using two supports, dried bloodspot cards (DBS, n = 48 FM and n = 46 LC) and volumetric absorptive micro-sampling tips (VAMS, n = 39 FM and n = 39 LC). A semi-permeable membrane (10 kDa) was used to extract low molecular fraction (LMF) from the blood samples, and Raman spectra were acquired using SERS with gold nanoparticles (AuNPs). Soft independent modelling of class analogy (SIMCA) models developed with spectral data of blood samples collected in VAMS tips showed superior performance with a validation performance of 100% accuracy, sensitivity, and specificity, achieving an excellent classification accuracy of 0.86 area under the curve (AUC). Amide groups, aromatic and acidic amino acids were responsible for the discrimination patterns among FM and LC syndromes, emphasizing the findings from our previous studies. Overall, our results demonstrate the ability of AuNP SERS to identify unique metabolites that can be potentially used as spectral biomarkers to differentiate FM and LC. [ABSTRACT FROM AUTHOR]

It is fairly easy to generate a surface enhanced Raman scattering (SERS) signal. However, there are several issues to be aware of when trying to use these signals in analytical applications. The SERS signal arises from the combination of the number of molecules (N), the polarizability or cross section of the molecule ([sigma]), and the electric field (E) experienced by the molecules. Understanding how these different variables interact to generate the enhanced SERS response is the key to applying SERS accurately. Here, we try to share experiences and some helpful references to assist people interested in applications using SERS., It has been more than 40 years since the realization that Raman signals are enhanced on nanostructured metal surfaces (1). Figure 1 illustrates the advantages of surface enhanced Raman scattering [...]

The ability to enhance the Raman signal from low concentrations of molecules using nanoparticles has made surface-enhanced Raman scattering (SERS) an attractive approach for trace detection in diverse applications in medicine, energy and the environment (1). Understanding SERS has improved significantly since the initial discovery in the 1970s (2,3). The detection and imaging, via tip-enhanced Raman scattering (TERS), of individual molecules suggests the ultimate in detection sensitivity (4-7). Particularly, recognizing how the energy from the excitation laser is concentrated by the nanoparticles through localized surface plasmon resonances has helped foster understanding of the appropriate experimental conditions to use for SERS measurements. Hot spots are important for generating the largest enhancements (8). In addition to enhancing the local electric field, other effects can occur on the surface of nanoparticles and impact the observed signals. Considering how the excitation laser intensity is concentrated and confined into small regions, it is important to consider the incident laser power. When performing SERS experiments, the excitation laser power needs to be kept at a level that enables detection but avoids damaging the sample., Generally, surface-enhanced Raman spectroscopy (SERS) practitioners often recommend the laser power be kept below 1 mW in a diffraction limited laser spot. The spot size in a microscope objective can [...]

Thin films of noble metals deposited by physical vapor deposition (PVD) are a simple substrate commonly used in surface-enhanced spectroscopies. The morphology and gap spacing of these plasmonic substrates are key factors in the Raman enhancements observed from molecules in the optical near field. The nanometer gaps between nanostructured features of the substrate are associated with the strongest fields and the greatest enhancement of light-driven processes (scattering, absorption, fluorescence) that occur near the surface. Results shown here illustrate that chemical adsorbates and solvents interacting with the substrate can induce changes in the atomic, nanoscale, and mesoscale morphology of the plasmonic substrate, possibly leading to in situ species that play a role in the enhancement mechanisms associated with plasmonic nanostructures. In this work, we report on the morphology changes induced by functionalizing nano-island films (NIF) of silver and gold (film thickness = 4-30 nm) in thiol solutions (thiophenol and 1-hexanethiol). The adsorbate-substrate interaction is hypothesized to cause aggregation or annealing-like surface rearrangements. NIF substrates of thickness, The enhancement of Raman scattering from molecules on the surface of plasmonic nanostructures (so-called surface-enhanced Raman scattering, or SERS) has been studied extensively for trace detection of analytes in a [...]

Benjamin Franklin was a preeminent proponent of the new colonial and Continental paper monetary system in 18th-century America. He established a network of printers, designing and printing money notes at the same time. Franklin recognized the necessity of paper money in breaking American dependence on the British trading system, and he helped print Continental money to finance the American War of Independence. We use a unique combination of nondistractive, microdestructive, and advanced atomic-level imaging methods, including Raman, Infrared, electron energy loss spectroscopy, X-ray diffraction, X-ray fluorescence, and aberration-corrected scanning transmission electron microscopy, to analyze pre-Federal American paper money from the Rare Books and Special Collections of the Hesburgh Library at the University of Notre Dame. We investigate and compare the chemical compositions of the paper fibers, the inks, and fillers made of special crystals in the bills printed by Franklin’s printing network, other colonial printers, and counterfeit money. Our results reveal previously unknown ways that Franklin developed to safeguard printed money notes against counterfeiting. Franklin used natural graphite pigments to print money and developed durable “money paper” with colored fibers and translucent muscovite fillers, along with his own unique designs of “nature-printed” patterns and paper watermarks. These features and inventions made pre-Federal American paper currency an archetype for developing paper money for centuries to come. Our multiscale analysis also provides essential information for the preservation of historical paper money. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering (SERS) has become a powerful technique for trace analysis of biomolecules. The use of SERS-tags has evolved into clinical diagnostics; the enhancement of the intrinsic signal of biomolecules on SERS active materials shows tremendous promise for the analysis of biomolecules and potential biomedical assays. The detection of the de novo signal from a wide range of biomolecules has been reported to date. In this review, we examine different classes of biomolecules for the signals observed and experimental details that enable their detection. In particular, we survey nucleic acids, amino acids, peptides, proteins, metabolites, and pathogens. The signals observed show that the interaction of the biomolecule with the enhancing nanostructure has a significant influence on the observed spectrum. Additional experiments demonstrate that internal standards can correct for intensity fluctuations and provide quantitative analysis. Experimental methods that control the interaction at the surface are providing for reproducible SERS signals. Results suggest that combining advances in methodology with the development of libraries for SERS spectra may enable the characterization of biomolecules complementary to other existing methods.

Advances in instrumentation and data analysis suggest that surface enhanced Raman scattering (SERS) is a powerful tool to characterize complex samples. Since the initial experiments and subsequent realization that Raman [...]

Undergraduate students are not being taught science, technology, engineering and mathematics (STEM) subjects as well as they need to be (1). Too often, faculty members talk at students rather than [...]

In order to facilitate nanoparticle-enhanced Raman imaging of complicated biological specimens, we have examined the use of higher order modes with radial and azimuthal polarizations focused onto a Au nanoparticle atomic force microscope (AFM) tip utilizing a backscattering reflection configuration. When comparing the Raman intensity profiles with the observed sample topography, the radial-polarized configuration demonstrates enhanced spatial resolution. This enhanced resolution results from the direction of the induced electron oscillation in the metal nanoparticle oriented by the electromagnetic field at the laser focus. The electric field component along the direction of laser propagation, attendant to the radial polarization, creates an enhanced field along the z-axis and normal to the sample. Substantial enhancement is observed utilizing an intermediate numerical aperture objective (NA = 0.7), necessary for backscattering measurements. The azimuthal polarization, similar to linear polarization, results in an enhanced field predominantly parallel to the sample, resulting in imaging artifacts. The Raman intensity profiles observed as the exciting laser polarization is switched between either a radially polarized or an azimuthally polarized state illustrate these imaging artifacts. Because azimuthal polarization arises readily from changes in the incident polarization onto the mode converter, the results presented here aid in identifying such artifacts when analyzing nanoparticle-enhanced Raman spectroscopic images. Due to the power law decay of the enhanced field, an enhancement orientation normal to the sample enables contrast between structures smaller than the tip dimensions as the apex of the nanoparticle tip, where the enhancement is strongest, passes over the sample. These effects are demonstrated using both carbon nanotube and fixed biological samples. 10.1021/ac901789w

We report on the potential-dependent behavior of the zwitterionic molecule p-aminobenzoic acid (PABA) at a Ag(111) electrode surface. Infrared--visible sum frequency generation spectroscopy (SFG) in tandem with electrochemical capacitance and CV measurements are used to study the effects of applied potential on the adsorption and orientation of PABA. Changes in the SFG signal indicate that PABA changes orientation in response to the charge on the electrode surface, orienting one way positive of the potential of zero charge (pzc) and oppositely negative of the pzc. At positive potentials, a phase change is observed associated with the formation of a condensed layer. PABA is observed to remain on the surface at all potentials examined. These results show that the orientation of small molecules with large dipoles, like zwitterions, can be controlled by applied potential.

Infrared--visible sum frequency generation spectroscopy is used to investigate the corrosion inhibitor benzotriazole (BTAH) adsorbed on Cu(100) and Cu(111) in acidic solution. Potential-dependent in situ spectra indicate that the adsorbed molecule is the benzotriazole anion (BT[A.sup.-]) at all potentials investigated. The Cu(100) surface is shown to form an ordered adlayer at all potentials probed, while the Cu(111) face is shown to be disordered at negative potentials, but to order with applied positive potential. The ordered adlayer is shown to consist of the BT[A.sup.-] in two configurations, one coordinated to the surface and [Cu.sup.+] ions in solution and the other coordinated only to the surface. The BT[A.sup.-] coordinated to [Cu.sup.+] is shown to be more stable with respect to [Cl.sup.-] addition than BT[A.sup.-] coordinated to only the surface. This study demonstrates the viability of using sum frequency generation to study corrosion inhibition in situ.