Cindy Delonas

Raman imaging manufacturer WITec (Ulm, Germany) is expanding its headquarters building. The expansion creates more office space for production and quality assurance, laboratories for development and customer demonstrations or sample measurements, larger conference rooms, and greater logistical capability. Completed, the new addition will double the amount of space at WITec’s Ulm location.

“Our headquarters was purpose-built to encourage cross-departmental interaction, from development through shipping, and it's had a very positive effect on the dynamics and performance of ourcompany,” Olaf Hollricher, the co-founder and managing director of research and development at WITec said in a statement, explaining that the expansion “will allow WITec to scale up while adhering to this concept.”

Construction of the WITec’s additional space will continue through 2020, with an anticipated opening toward the end of 2021.

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Raman imaging manufacturer WITec (Ulm, Germany) is expanding its headquarters building.

WITec GmbH Expands Ulm Headquarters Building

Modeling, rather than measuring infrared (IR) and other spectra in order to account for morphological forms that may be encountered for solids as well as substances that incorporate at least one liquid phase, including bulk mixtures, aerosols, thin films on substrates and others, has become the technique of choice, compared to measuring. Timothy J. Johnson and Tanya L. Myers, the 2019 winners of the Applied Spectroscopy William F. Meggers Award, have been exploring novel methods using infrared (IR) and visible reflectance spectroscopies for identification of target chemicals through derivation of the 

 optical constants. For their winning paper, Johnson and Myers created a spectroscopic library of 57 liquids for which they measured the complex refractive index, data that can be used for optical modeling and other purposes. They shared some of the details of their work with 

In a recent paper (1), you and your team discuss your creation of a library of 57 liquids in which you measured the complex optical constants 

(the complex component, proportional to absorption) for your selected library of compounds. These were determined to allow modeling of most optical phenomena in media, and their corresponding interfaces of reflection, refraction, and dispersion. Can you describe how this work is an advancement or benefit for spectroscopists?

	Accurate values of the optical constants are critical for modeling the real-world reflectance spectra of liquids, since liquid species can occur in many forms. The research represented in this paper helps fulfill this need by providing a spectral database of the optical constants that can be used by researchers around the world to better detect and identify (hazardous) chemicals using infrared spectroscopy.

 why specifically it is important for spectroscopists to use the optical constants of 

 to model optical phenomena at interfaces such as reflection, refraction, and dispersion?

	Due to the phenomena of reflection, refraction and absorption, the amplitude and spectral composition of light changes every time light passes between two media with different refractive indices. The refractive index is actually a complex quantity with 

 representing the real component corresponding to dispersion and the complex component 

 corresponding to absorption. The amplitude of 

 in the two media determine how much of the light is reflected/refracted/attenuated at each interface and in each medium. Calculations are necessary to model the phenomena because the geometric form for both solids and liquids are seldom found as a homogenous medium as are gases. Rather, solids and liquids can manifest not only as bulk but also as particles, droplets, spheroids, mists, aerosols, thin layers, thick layers, and so on.  Each one of the forms represents complex geometric interfaces for media of different refractive indices and thus different amounts of reflected light with different spectral content. To move beyond all but the simplest forms such as bulk, physical models are needed to calculate the many effects using

How did you go about selecting your set of 57 liquids for determination of 

	The list of chemicals was actually selected by an ad-hoc group of scientists working for an Intelligence Advanced Research Projects Activity (IARPA) program to improve standoff infrared laser detection of chemicals and chemicals on surfaces. However, we did endeavor to ensure that the list of liquids was “chemically diverse” by including both inorganic and organic species with varying functional groups (alcohols, ketones, amines, sulfur, and phosphorous compounds and others). We also worked to ensure that the list included chemicals of significantly differing physical properties such as viscosity and boiling point. 

How does your approach differ from the literature or other published work? What is it about your approach that makes the calibrated liquid 

 values you obtained more useful or accessible for different applications than previous work or estimations?

	In the first instance, our methodologies were based largely on the work of Professor John Bertie and colleagues at the University of Alberta as published in the 1990s.  Indeed, some of the software programs to derive the n/k values from the measurement were downloaded from his freeware site. However, we improved these protocols by i) creating and using shorter cells (for the strong absorbers), ii) using multiple-path lengths (up to 10) to account for both strong and weak absorbers and to improve the signal-to-noise, iii) improving data reduction methods that resulted in spectra that are more linear in 

 across different parts of the spectrum by intra-calibrating absorption bands of different strength, and iv) using an improved multi-wavelength approach with a Sellmeier fit to obtain the best scalar value of 

 at the highest wavenumber used in the measurement, and finally v) applying extensive QAQC methods to vet the 

 data. The end product is a set of liquids n/k data that have greatly improved linearity and higher fidelity than previously available. The data are publicly available both at the 

 web site as supplemental material as well as at the NIST chemistry webbook site.

What were some of the main challenges you faced in obtaining 

 values for liquids with high confidence?

	There were a few experimental challenges. In order to obtain linear responses for the very strong absorption bands, it was necessary to prepare liquid cells of very short path length, just a few µm. To achieve such short path lengths, we crushed the cells in a hydraulic press, and many of the cells (literally) cracked under pressure. A second experimental challenge was filling those very same cells: Because the gap between the windows was, for example, only 2 or 3 µm, we implemented a dual syringe technique to fill the cells that involved using the first syringe to inject the liquid and the second, which was connected to the outlet, to simultaneously withdraw the air and pull the liquid through. Filling such cells became quite problematic, especially for the highly viscous species. In addition, after filling the cells, the path length may have also increased, particularly for the short cells; thus, we employed an iterative approach to optimize the calculated path length values by minimizing the differences between measured absorbance values and those calculated using the Beer-Lambert law of absorption.

What would you say is the key benefit to spectroscopic measurements as a result of your work?

	There are two major benefits to the spectroscopy community: First, we provide a publicly available free spectroscopic database of a large (and growing) number of liquids that can be used to model spectra and reduce data for dozens of applications. The data are of very high quality. Second, the data themselves can be used as calibration reference spectra for many applications and instruments. 

Do you plan to continue expanding this work? What are the next steps in your research related to this work?

	We of course hope to continue this work since it would be advantageous to include several hundred species relevant to many other applications, but as a federal laboratory, our research is subject to continued funding from sponsors. Work is also currently under way to expand the wavelength range to include the near-infrared (for example, to 10,000 cm

,  1.0 µm wavelength) as this wavelength range has proven very useful for many (industrial) applications.

		T.L Myers, R.G. Tonkyn, T.O. Danby, M.S. Taubman, B.E. Bernacki, J.C. Birnbaum, S.W. Sharpe, and T.J. Johnson, 

		B.M. DeVetter, T.L. Myers, B.D. Cannon, N.K. Scharko, M.R. Kelly-Gorham, J.F. Corbey, A.L. Schemer-Kohrn, C.T. Resch, D.D. Reilly, and T.J. Johnson, 

		T.L. Myers, C.S. Brauer, Y.-F. Su, T.A. Blake, R.G. Tonkyn, A.B. Ertel, T.J. Johnson and R.L. Richardson, 

 is a senior research scientist at the Pacific Northwest National Laboratory. She received her PhD and MS in chemistry from the University of Chicago. She has more than 25 years of extensive experience with laser-based experiments in chemical physics, including high-resolution IR spectroscopy. She is the author of more than 40 refereed publications.

is a senior research scientist at PNNL who specializes in the THz IR, near-IR, and UV-vis domains. He received his PhD in chemical physics from Washington State University, where he studied crystallographic effects on the Raman and IR spectra of solids. He is the inventor on two U.S. patents, co-author of one book, and the author of more than 75 refereed publications.

Timothy J. Johnson and Tanya L. Myers, the 2019 winners of the Applied Spectroscopy William F. Meggers Award, have been exploring novel methods using infrared (IR) and visible reflectance spectroscopies for identification of target chemicals through derivation of the n and k optical constants. For their winning paper, Johnson and Myers created a spectroscopic library of 57 liquids for which they measured the complex refractive index, data that can be used for optical modeling and other purposes. They shared some of the details of their work with Spectroscopy.

Optical Modeling and Detection of Infrared and Other Spectra

	The 67th Conference on Mass Spectrometry and Allied Topics is set to take place June 2–6 at the Georgia World Congress Center in Atlanta, Georgia.

	On Sunday, four tutorial lectures will be given, in two sessions, both starting at 5:00 pm. Tutorial Session I will be chaired by Susan Richardson of the University of South Carolina. Stephen Blanksby of Queensland University of Technology. Gavin Reid of the University of Melbourne will present the first lecture, on lipodomics. At 5:45 pm, Enrico Davoli of the Mario Negri Institute will present the second tutorial, on targeted imaging.

	Erin Baker of North Carolina University will chair Tutorial Session II from 5:00 pm to 6:30 pm. "Native Mass Spectrometry" is the topic of the first tutorial, presented by Michal Sharon of the Weizmann Institute. Following that talk, "Data-Independent Acquisition" will be presented by Birgit Schilling of The Buck Institute.

	The tutorials are followed by the conference opening plenary lecture at 6:45 pm. Mark Z. Jacobson of Stanford University will present a talk titled "Transitioning the World Energy for All Purposes to Stable Electricity Powered by 100% Wind, Water, and Sunlight."

	A welcome reception will follow the plenary lecture, taking place from 7:45 pm until 9:00 pm in the Poster and Exhibit Hall.

	Jefferey Shabanowitz will receive the Al Yergey Mass Spectrometry Scientist Award Monday at 4:45 pm. The award recognizes dedication and significant contributions to mass spectrometry-based science by "unsung heroes." Shabanowitz played a major role in the development of peptide sequence analysis by tandem mass spectrometry.

	The John B. Fenn Award for a Distinguished Contribution in Mass Spectrometry will then be presented to John R. Yates III of The Scripps Research Institute. The award recognizes Yates for his development of automated, large-scale interpretation of peptide tandem mass spectral data. His SEQUEST algorithm laid a critical foundation for the field of proteomics and has enhanced the accuracy and effectiveness of mass spectrometry for understanding important biological and clinical questions. Yates will then give an award lecture.

	The Biemann Medal will be awarded to Sarah Trimpin of Wayne State University at 4:45 p.m. The Biemann Medal is awarded to an individual early in his or her career to recognize significant achievement in basic or applied mass spectrometry. Trimpin's award is for unusual observation of highly charged protein ions in an atmospheric pressure MALDI experiment that led to her discovery that ionization occurs simply bypassing compounds through the inlet of a mass spectrometer.

	On Thursday, Lilly D'Angelo of Global Food & Beverage Technology Associates will give a plenary lecture at 4:45 p.m. titled "Chemistry of Food and Soft Drinks."

	A closing event at the Georgia Aquarium gets under way at 6:30 pm on Thursday. Tickets must be purchased in advance by noon Monday. The ticket cost is $40 per person and includes a dinner buffet, open until 8:00 pm, with dessert and a cash bar available until the close of the event, at 9:30 pm. Tickets also include one drink per ticket for soda, beer, or wine.

	The 68th Annual ASMS Conference will be held May 31–June 4 in Houston, Texas. For more information, visit 

We present a brief preview of this year’s ASMS conference, taking place June 2–6, 2019, in Atlanta, Georgia.

Preview of the 67th Conference on Mass Spectrometry and Allied Topics

Advanced techniques in tissue engineering hold promise to those who suffer from damage to or degeneration of joint cartilage. But some challenges exist for tissue engineers to gain a better understanding of the development of these constructs and their mechanical properties. Nancy Pleshko, a professor of Bioengineering at Temple University (Philadelphia, Pennsylvania) has been studying the use of Fourier-transform–infrared imaging spectroscopy (FT-IRIS) as well as near-infrared (NIR) spectroscopy to explore the ways in which these techniques can aid in the development of replacement tissue. We spoke to her about her research and findings.

In a recent paper about tissue engineering and its ability to repair defects in articular cartilage (1) you discussed the use of FT-IRIS to study the distribution of water and extracellular matrix produced in engineered constructs such as those that are created for cartilage repair. Why is this an important study, and how might it help patients with osteoarthritis?  

	TTissue engineering strategies are being investigated for repair of tissues that are challenging to regenerate naturally, such as articular cartilage. Osteoarthritis is a disease that results in degeneration of joint (articular) cartilage, resulting in pain and mobility loss for millions. Development of engineered constructs could be a solution for tissue repair, but the compositional properties of the native cartilage should ideally be duplicated in the engineered tissues. The primary tissue components are extracellular matrix, including collagen and proteoglycans, and water. Thus, we need to know the relative amount and distribution of these components in both native tissue and engineered constructs.

What are the advantages of using FT-IRIS over more traditional techniques that allow a visual comparison between native cartilage and engineered cartilage? You reported spatial resolution of 25 

m  to permit visualization of matrix and water throughout the tissue. What would be the ideal spatial resolution for this work?  

	There are several advantages of using this technique. First, FT–IRIS permits quantification of compositional information without the addition of external contrast agents. Different protein components, or mineral, if present, and water, can be evaluated in one unstained tissue section. This saves a significant amount of tissue preparation time and preserves the rest of the tissue for additional studies. Further, many other techniques can’t be used to visualize water distribution, so this is certainly an advantage of this modality. The ideal spatial resolution would vary, depending on the question of interest. In cartilage, for example, spatial resolution in the 10–25 mm range is acceptable, as this can be related to variations in different zones of cartilage. However, it could be desirable to have better spatial resolution if there is a question of what specifically a cell is producing. Then one may want to investigate this at a better resolution, which could theoretically be done with attenuated total reflection (ATR) spectral imaging.

What challenges did you face in developing this method? Did you encounter problems with sample preparation and cryosectioning 80-

m sections of native and engineered cartilage?

	The primary challenge was optimizing the sample thickness to enable collection of data from the same sample in both the mid-IR and NIR spectral regions. The sample had to be thick enough to obtain a reasonable NIR signal, but not so thick that the mid-IR absorbances were off scale. Investigation of mid-IR absorbances related to collagen and proteoglycan that have small absorptivity coefficients enabled us to achieve this goal. But, protein absorbances that are typically investigated in the mid-IR, such as the amide I absorbance, would not be feasible in an 80-mm tissue section.

Another recent paper of yours describes how NIR spectroscopy may be an alternative to destructive biochemical and mechanical methods for the evaluation of hyaluronic acid (HA) (2). What makes NIR a good technique for evaluating HA? 

	In that study, we used an NIR fiber optic to investigate hyaluronic acid–based  developing engineered cartilage tissues. Typically, engineered tissues have to be harvested for implantation at an optimal timepoint, and determination of that timepoint is challenging. In particular, if, for example, you’re growing six constructs, you may harvest one, and perform a biochemical analysis to assess the composition, and whether or not the construct is ready to implant. However, the variation in composition among constructs can be high, even if grown in the exact same conditions. So, relying on the outcome from one construct to reflect the composition of another in the same batch isn’t always accurate. Thus, collection of NIR fiber optic data that reflect compositional data of an individual construct is an ideal solution.

What results have you achieved so far, and what differences, if any, can you observe between native and engineered cartilage using FT-IR imaging and NIR? 

	So far, we have successfully developed multivariate models based on NIR fiber optic data to predict compositional properties of developing engineered cartilage. We have also used FT-IR imaging data to help us understand how the fiber optic data change based on distribution of various components in the tissues, and how sensitive the fiber optic data are to these variations. The combination of the two different sampling modalities enables us to more fully understand the tissue development, and how to optimize our data collection and processing.

	The next steps for us are going to be very exciting! We will grow engineered cartilage in the laboratory, identify optimal constructs based on our NIR fiber optic data, and then harvest them to implant in a preclinical model. Further, we will use the same fiber optic sampling to assess how the engineered construct composition changes once it is implanted in vivo. If these experiments are successful, it will be a major step towards improved ability to select ideal constructs for tissue repair. 

		J.P. Karchner, W. Querido, S. Kandel, and N. Pleshko, 

		F. Yousefi, M. Kim, S.Y. Nahri, R. L. Mauck, and N. Pleshko, 

(1,2) (2018). doi:10.1089/ten.tea.2017.0035

Author | Cindy Delonas

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