Mark A. Arnold's research while affiliated with University of Iowa and other places

Publications (153)

Article
Full-text available
Background Conventional home blood glucose measurements require a sample of blood that is obtained by puncturing the skin at the fingertip. To avoid the pain associated with this procedure, there is high demand for medical products that allow glucose monitoring without blood sampling. In this review article, all such products are presented. Method...
Article
The next-generation artificial pancreas is under development with the goal to enhance tight glycemic control for people with type 1 diabetes. Such technology requires the integration of a chemical sensing unit combined with an insulin infusion device controlled by an algorithm capable of autonomous operation. The potential of near-infrared spectros...
Article
Terahertz (THz) time-domain spectroscopy provides a direct and nondestructive method for measuring the dielectric properties of materials directly from the phase delay of coherent electromagnetic radiation propagating through the sample. In cases when crystals are embedded within an inert polymeric pellet, the Landau, Lifshitz, and Looyenga (LLL) e...
Article
Interest in terahertz (THz) optoelectronics is driven by applications such as ultrawideband communication systems, atmospheric monitoring, airport security scanners, and biomedical imaging and sensing. In article number 1900071, Hongtao Ding and co‐workers give an overview of THz bandpass metamaterials, with a focus on the design strategies, fabric...
Article
Development of terahertz (THz) sources, detectors, and optical components has been an active area of research across the globe. The interest in THz optoelectronics is driven by the various applications they have enabled, such as ultrawide‐band communication systems, air‐ and space‐borne astronomy, atmospheric monitoring, small‐scale radar, airport...
Article
Development of terahertz (THz) sources, detectors, and optical components has been an active area of research across the globe. The interest in THz optoelectronics is driven by the various applications they have enabled, such as ultrawide‐band communication systems, air‐ and space‐borne astronomy, atmospheric monitoring, small‐scale radar, airport...
Article
Full-text available
Terahertz (THz) spectroscopy has been put forth as a non-contact, analytical probe to characterize the intermolecular interactions of biologically active molecules, specifically as a way to understand, better develop, and use active pharmaceutical ingredients. An obstacle towards fully utilizing this technique as a probe is the need to couple featu...
Article
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Terahertz (THz) imaging has attracted much attention within the past decade as an emerging nondestructive evaluation technique. In this paper, we present a novel Laser-based Metamaterial Fabrication (LMF) process for high-throughput fabrication of transparent conducting surfaces on dielectric substrates such as glass, quartz and polymers to achieve...
Article
A noninvasive method for detecting episodes of nocturnal hypoglycemia is demonstrated with in vivo measurements made with a rat animal model. Employing spectra collected from the near-infrared combination region of 4000-5000 cm-1, piecewise linear discriminant analysis (PLDA) is used to classify spectra into alarm and non-alarm data classes on the...
Article
Full-text available
A novel application of terahertz time-domain spectroscopy (THz-TDS) is described for the determination of permittivity and polarizability of organic crystals, as exemplified by measurements with the polymorph I form of crystalline aspirin (acetylsalicylic acid). The coherent nature of the THz pulse experiment, coupled with gated-detection, permits...
Article
Molar absorptivity is a fundamental molecular property that quantifies absorption strength as a function of wavelength. Absolute measurements of molar absorptivity demand accounting for all mechanisms of light attenuation, including reflective losses at interfaces associated with the sample. Ideally, such measurements are performed in nonabsorbing...
Article
The production of norovirus virus-like particles (NoV VLPs) displaying NY-ESO-1 cancer testis antigen in Pichia pastoris BG11 Mut(S) has been enhanced through feed-strategy optimization using a near-infrared bioprocess monitor (RTBio® Bioprocess Monitor, ASL Analytical, Inc.), capable of monitoring and controlling the concentrations of glycerol and...
Article
Analytical potential of terahertz (THz) spectroscopy is assessed by comparing selectivity for a set of eight environmentally important gases over THz and infrared (IR) optical frequencies. Se-lectivity coefficients are determined over selected spectral regions for acetaldehyde, acetoni-trile, ethanol, water, methanol, ammonia, propionaldehyde, and...
Article
A correlation between Young's modulus, as determined by using nanoindentation atomic force microscopy (AFM), and atomic polarizability is observed for members of a series of cocrystals based on systematic changes to one cocrystal component. Time domain spectroscopy over terahertz frequencies (THz-TDS) is used for the first time to directly measure...
Article
a b s t r a c t Monoclonal antibody production in glycoengineered Pichia pastoris was optimized for high cell density fed-batch fermentations. Results show that antibody productivity was 1.72-fold higher when maintain-ing oxygen-limited conditions compared to methanol-limited conditions during the protein production phase of the bioprocess. Under o...
Article
Near-infrared spectroscopy is considered to be one of the most promising spectroscopic techniques for upstream bioprocess monitoring and control. Traditionally the nature of near-infrared spectroscopy has demanded multivariate calibration models to relate spectral variance to analyte concentrations. The resulting analytical measurements have proven...
Article
Near infrared spectroscopy is demonstrated as a suitable method for monitoring real time cell density and concentrations of glucose and lactate during insect cell cultivation. The utility of this approach is illustrated during the cultivation of Trichoplusia ni BTI-Tn-5B1-4 insect cells in a stirred-tank bioreactor. On-line near infrared measuremen...
Article
Pellets composed of different weight-percent (wt-%) of lactose within a polyethylene (PE) matrix are used to examine how the physical thickness of solid samples impact analytical measurements performed over terahertz (THz) frequencies when using time-domain THz spectroscopy. Results indicate that the thickness of each pellet depends on the mass and...
Article
Chemical imaging is demonstrated by using an innovative near infrared spectrometer that uses a digital micro-mirror array device (DMD) to provide both spatial and spectral resolution. Hadamard transform spectroscopy is used to enhance the signal-to-noise ratio of the measurement compared to single point raster scanning. The concept is demonstrated...
Article
Advances in ultrafast lasers and semiconductor technologies have facilitated access to the terahertz (THz) frequency range for spectroscopic and imaging purposes. THz time-domain spectroscopy (TDS) is commonly used to acquire spectral data having high signal-to-noise ratios (SNRs) over a broad range of THz frequencies. THz-TDS instrumentation is co...
Article
A novel solid-state near-infrared spectrometer is presented based on a digital micro-mirror array device (DMD) that is well designed for Hadamard transform spectroscopy. This spectrometer is designed for the collection of transmission spectra over the C-H first overtone region of the near-infrared spectrum (6500-5500 cm(-1)). A spectral resolution...
Article
A novel strategy is demonstrated to improve the accuracy for determination of polyethylene (PE) density using Raman spectroscopy by optimizing the temperature of sample measurement. Spectral features associated with the conformation change of the polymer induced by temperature may provide valuable information to quantify important polymer propertie...
Article
Background: Movement of the optical interface used to collect noninvasive near-infrared spectra is known to dramatically increase prediction errors for glucose concentration measurements within the interstitial fluid of living rat skin. Prediction errors increase by more than 2.5-fold when the interface is moved before each non-invasive measuremen...
Article
Optimal filter design of two-channel near-infrared filter photometers is investigated for simulated two-component systems consisting of an analyte and a spectrally overlapping interferent. The degree of overlap between the analyte and interferent bands is varied over three levels. The optimal design is obtained for three cases: a source or backgrou...
Article
Background: Noninvasive glucose measurements are possible by analysis of transmitted near-infrared light over the 4000- to 5000-cm(-1) spectral range. Such measurements are highly sensitive to the exact position of the fiber-optic interface on the surface of the skin sample. A critical question is the degree of heterogeneity of the major chemical...
Article
Near-infrared spectroscopy offers the potential for direct in situ analysis in complex biological systems. Chemical selectivity is a critical issue for such measurements given the extent of spectral overlap of overtone and combination spectra. In this work, the chemical basis of selectivity is investigated for a set of multivariate calibration mode...
Article
Noninvasive glucose sensing is an active area of research and development with many different approaches being explored since the 1980s. The promise of this approach is to provide a measure of the blood glucose concentration in a rapid, painless, and cost-effective manner so that people with diabetes can better maintain tight glycemic control, ther...
Article
This paper provides a broad overview of the field of fiber optic chemical sensors. Several different types of fiber optic sensors and probes are described, and references are cited for each category discussed.
Article
Full-text available
The ex vivo removal of urea during hemodialysis treatments is monitored in real time with a noninvasive near-infrared spectrometer. The spectrometer uses a temperature-controlled acousto optical tunable filter (AOFT) in conjunction with a thermoelectrically cooled extended wavelength InGaAs detector to provide spectra with a 20 cm -1 resolution ove...
Article
Selectivity is paramount for the successful implementation of noninvasive spectroscopic sensing for the painless measurement of blood glucose concentrations in people with diabetes. Selectivity issues are explored for different multivariate calibration models based on noninvasive near-infrared spectra collected from an animal model. Noninvasive nea...
Article
Partial least-squares (PLS) calibration models have been generated from a series of near-infrared (near-IR) and Raman spectra acquired separately from sixty different mixed solutions of glucose, lactate, and urea in aqueous phosphate buffer. Independent PLS models were prepared and compared for glucose, lactate, and urea. Near-IR and Raman spectral...
Article
Pure component selectivity analysis (PCSA) was successfully utilized to enhance the robustness of a partial least squares (PLS) model by examining the selectivity of a given component to other components. The samples used in this study were composed of NH4OH, H2O2 and H2O, a popular etchant solution in the electronic industry. Corresponding near-in...
Article
Full-text available
Tight control of blood glucose levels has been shown to dramatically reduce the long-term complications of diabetes. Current invasive technology for monitoring glucose levels is effective but underutilized by people with diabetes because of the pain of repeated finger-sticks, the inconvenience of handling samples of blood, and the cost of reagent s...
Article
We have performed in vivo measurements of near-infrared rat skin absorption in the 4000-5000-cm(-1) spectral range (2.0-2.5-microm wavelength) during a glucose clamp experiment in order to identify the presence of glucose-specific spectral information. Spectra were collected during an initial 3-h period where the animal's blood glucose concentratio...
Article
Full-text available
Optical sensing of glucose would allow more frequent monitoring and tighter glucose control for people with diabetes. The key to a successful optical noninvasive measurement of glucose is the collection of an optical spectrum with a very high signal-to-noise ratio in a spectral region with significant glucose absorption. Unfortunately, the optical...
Article
Optical properties of whole bovine blood are examined under conditions of different glucose loadings. Partial least-squares (PLS) is used to compute calibration models for glucose from spectra collected over the combination spectral region (5000 - 4000 cm- 1) and first overtone - short wavelength spectral regions (9000 - 5400 cm-1). These models ac...
Article
The ability to measure glucose noninvasively in human subjects is a major objective for many research groups. Success will revolutionize the treatment of diabetes by providing a means to improve glycemic control, thereby delaying the onset of the medical complications associated with this disease. This article focuses on the current state of the ar...
Article
Optical properties of whole bovine blood are examined under conditions of different glucose loadings. A strong dependency is established between the scattering properties of the whole blood matrix and the concentration of glucose. This dependency is explained in terms of variations in the refractive index mismatch between the scattering bodies (pre...
Article
Molar absorptivities are measured for water, glucose, alanine, ascorbate, lactate, triacetin, and urea in the near-infrared spectral region at 37 degrees C. Values are based on the Beer-Lambert law and cover the first overtone (1550-1850 nm; 6450-5400 cm(-1)) and combination (2000-2500 nm; 4000-5000 cm(-1)) spectral windows through aqueous media. A...
Article
Partial least squares calibration models are compared for the measurement of glucose, lactate, urea, ascorbate, triacetin, and alanine in aqueous solutions from single-beam spectra collected over the first overtone (6500-5500 cm(-1)) and the combination (5000-4000 cm(-1)) regions of the near-infrared spectrum. Spectra are collected under two sets o...
Article
We have shown previously that large high-quality single protein crystals can be grown by varying temperature in a predetermined fashion such that the solution supersaturation and the rate of crystal growth are maintained at a constant value in batch crystallization systems. Here we have adapted the constant supersaturation control (CSC) methodology...
Article
PC-3 human prostate cancer cells have been cultivated in a rotating wall vessel in which glucose, lactate, and glutamine profiles were monitored noninvasively and in real time by near-infrared (NIR) spectroscopy. The calibration models were based on off-line spectra from tissue culture experiments described previously (Rhiel et al., Biotechnol Bioe...
Article
A novel procedure is proposed as a method to characterize the chemical basis of selectivity for multivariate calibration models. This procedure involves submitting pure component spectra of both the target analyte and suspected interferences to the calibration model in question. The resulting model output is analyzed and interpreted in terms of the...
Article
Optical properties of whole bovine blood are examined under conditions of different glucose loadings. A strong dependency is established between the scattering properties of the whole blood matrix and the concentration of glucose. This dependency is explained in terms of variations in the refractive index mismatch between the scattering bodies (pre...
Article
Full-text available
We describe online optical measurements of urea in the effluent dialysate line during regular hemodialysis treatment of several patients. Monitoring urea removal can provide valuable information about dialysis efficiency. Spectral measurements were performed with a Fourier-transform infrared spectrometer equipped with a flow-through cell. Spectra w...
Article
The transfer of multivariate calibration models is investigated between a primary (A) and two secondary Fourier transform near-infrared (near-IR) spectrometers (B, C). The application studied in this work is the use of bands in the near-IR combination region of 5000-4000 cm(-)(1) to determine physiological levels of glucose in a buffered aqueous ma...
Article
Full-text available
Single-beam spectra were collected over the combination region of the near-infrared spectrum for 80 samples collected from 15 people over a two-week period. Partial least-squares (PLS) regression was used to generate an optimized calibration model for urea. PLS calibration models accurately measure urea in the spent dialysate matrix. Prediction err...
Article
Infrared spectroscopy offers many attractive features for clinical measurements, such as reagent-less, noninvasive, nondestructive, and multicomponent analysis of complex samples. Recent reports have demonstrated the potential utility of infrared and near-infrared spectroscopy for measurements in treated and untreated samples of blood and other spe...
Article
The selectivity and robustness of near-infrared (near-IR) calibration models based on short-scan Fourier transform (FT) infrared interferogram data are explored. The calibration methodology used in this work employs bandpass digital filters to reduce the frequency content of the interferogram data, followed by the use of partial least-squares (PLS)...
Article
A probe-type oxygen sensor was developed utilizing a radioluminescent (RL)-based light source and a ruthenium-based sensing chemistry for monitoring the dissolved oxygen (DO) concentration in a modified version of the NASA-designed high aspect ratio vessel (HARV), a batch rotating wall vessel. This sensor provided the means to monitor the DO concen...
Article
Full-text available
LNCaP prostate cancer cells were grown under four unique cultivation conditions. Two types of bioreactor systems were used to observe the influence of low-shear culture conditions allowing for three-dimensional growth: a) a perfusion rotating wall vessel (RWV) bioreactor; and b) a high aspect ratio vessel (HARV) RWV bioreactor, with periodic medium...
Article
Four-channel Kromoscopic analysis is demonstrated for in vitro measurement of glucose in cow blood in the spectral range of the first overtone of CH stretching vibrations and also the short wavelength near infrared region. The sample set included 48 blood samples with glucose concentration randomly distributed in the range 4.55 -37.60 mM. Solid glu...
Article
A compact, flow-through oxygen sensor device based on luminescence quenching was used to monitor dissolved oxygen levels during mammalian cell growth on the STS-93 mission of the Columbia space shuttle. Excitation of an oxygen-sensitive ruthenium complex was provided by a radioluminescent light source (0.9 mm in diameter, 2.5 mm long), and the inte...
Article
The ability to quantify lysozyme is demonstrated for a series of aqueous samples with different degrees of scattering. Near-infrared spectra are collected for two sets of lysozyme/scattering solutions. In both sets of samples, the solutions are composed of lysozyme dissolved in acetate buffer with suspended monodisperse latex microspheres of polyst...
Article
Calibration standardization methodology for near-infrared (near-IR) spectroscopy is described for updating a partial least-squares calibration model to take into account changes in instrumental response. The guided model reoptimization (GMR) algorithm uses a transfer set of eight samples to characterize the new response and a database of previously...
Article
The ability of Kromoscopy to measure glucose selectively is demonstrated in solutions composed glucose, urea, triacetin, bovine serum albumin (BSA), cholesterol, and hemoglobin (Hb). Kromoscopic measurements are made with a four-channel instrument designed for measuring light between 1500 and 1900 nm. The channels are configured to respond to four...
Article
An adaptive calibration procedure is used to build selective multivariate calibration models for the measurement of glucose, lactate, glutamine, and ammonia in undiluted serum-based cell culture media. This adaptive procedure removes metabolism-induced covariance between these analytes in a series of calibration samples collected during the cultiva...
Article
The selectivity of a four-channel Kromoscopic analysis is demonstrated for the measurement of glucose in separate binary and tertiary matrices. A novel virtual search procedure is used to identify three different sets of four, overlapping transmission filters. The first filter set includes filters centered at 900, 1300, 1410, and 1538 nm and is sel...
Article
Large, high-quality protein crystals are required for the structural determination of proteins via X-ray diffraction. In this article, we propose a technique to facilitate the production of such crystals and validate its feasibility through simulations. An analytical method for protein aqueous solution based on a Fourier transform infrared (FTIR) s...
Article
Adenosine produces analgesia in the spinal cord and can be formed extracellularly through enzymatic conversion of adenine nucleotides. A transverse push–pull microprobe was developed and characterized to sample extracellular adenosine concentrations of the dorsal horn of the rat spinal cord. Samples collected via this sampling technique reveal that...
Article
Near-infrared spectroscopy is proposed as a method for providing real-time urea concentrations during hemodialysis treatments. The feasibility of such noninvasive urea measurements is evaluated in undiluted dialysate fluid. Near-infrared spectra were collected from calibration solutions of urea prepared in dialysate fluid. Spectra were collected ov...
Article
Kromoscopy involves the transmission of a broad band of electromagnetic radiation through the sample of interest. The transmitted light is collected and divided evenly into four detector channels with complementary bandpass functions. This optical configuration provides high signal-to-noise ratios that are ideal for analytical measurements. The mol...
Article
Proteins possess strong absorption features in the combination range (5000-4000 cm(-1)) of the near infrared (NIR) spectrum. These features can be used for quantitative analysis. Partial least squares (PLS) regression was used to analyze NIR spectra of lysozyme with the leave-one-out, full cross-validation method. A strategy for spectral range opti...
Article
Fourier transform near-infrared interferogram data are used to determine the physiological levels of glucose in a synthetic biological matrix consisting of varying levels of bovine serum albumin and triacetin in a pH 7.4 phosphate buffer. Finite impulse response (FIR) digital filters are applied to short segments of the interferogram data, and the...
Article
Digital Fourier filtering is used to produce a temperature-insensitive univariate calibration model for measuring lysozyme in aqueous solutions. Absorbance spectra over the 5000-4000 cm-1 spectral range are collected for lysozyme standards maintained at 14 degrees C. These spectra are used to compute the calibration model while a set of spectra col...
Article
Near-infrared (NIR) spectroscopy has been evaluated for monitor- ing the acid-catalyzed hydrolysis (thinning) of starch. In practice, the extent of starch hydrolysis is measured inuidity units, which correspond to a physical property of the hydrolyzed starch mate- rial. NIR spectra of samples taken periodically during a series of starch-thinning re...
Article
Noninvasive blood glucose measurements are characterized in human subjects. A series of first overtone transmission spectra are collected across the tongues of five human subjects with type 1 diabetes. The noninvasive human spectra are collected by an experimental protocol that is designed to minimize chance correlations with blood glucose levels....
Article
Full-text available
This study was undertaken to quantitate the impact of increasing sample complexity on near-infrared spectroscopic (NIRS) mea- surements of small molecules in aqueous solutions with varying numbers of components. Samples with 2, 6, or 10 varying com- ponents were investigated. Within the 10-component samples, three analytes were quanti® ed with erro...
Article
A series of potential indicator dyes is evaluated for use in the development of optical sensors for measuring sulfur dioxide in gaseous samples. Rhodamine B isothiocyanate is selected on the basis of relative sensitivity to dynamic quenching by sulfur dioxide and oxygen. A solid-state fluorometer is described for monitoring the sulfur dioxide induc...
Article
Six putative measurement sites were evaluated for noninvasive sensing of blood glucose by first-overtone near-infrared spectroscopy. The cheek, lower lip, upper lip, nasal septum, tongue, and webbing tissue between the thumb and forefinger were examined. These sites were evaluated on the basis of their chemical and physical properties as they perta...
Article
Near-infrared single-beam spectra are used to build partial least-squares (PLS) calibration models for the determination of glucose in biological matrices. Two different data sets of the same sample constituents are used in this investigation. The glucose samples consist of an aqueous matrix of varied concentrations of bovine serum albumin (BSA) an...
Article
Nonlinear model building techniques are applied to near-infrared spectra to predict glucose concentrations in samples containing an aqueous matrix of varied concentrations of bovine serum albumin (BSA) and triacetin. The triacetin is used to model triglycerides in human blood, and the BSA is used to model blood proteins. The non-linear model buildi...
Article
A flow injection method is described for the selective measurement of chromium(VI) in aqueous solutions. This method is based on the dynamic quenching of ruthenium(II) fluorescence. The detection limit is 0.43 ppm and 40 samples can be analyzed per hour. Selectivity is demonstrated over ferrous, nickel, cupric and zinc cations and no effect is obse...
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This paper reviews the concepts associated with chemical sensors. The important concepts are exempli®ed by a discussion of oxygen sensors.
Article
Partial least-squares (PLS) regression analysis was used to build calibration models for three unique spectral data sets of glucose in water. Spectra in the first data set were collected with a 2.0 mm optical pathlength. For these data, the measured root-mean-square (rms) noise of 100% lines over the 5975-5850 cm-1 spectral range was 4.5 micro-abso...
Article
An improved genetic algorithm (GA)-based wavelength selection procedure is developed to optimize both the near-infrared wavelengths used and the number of latent variables employed in building partial least-squares (PLS) calibration models. This GA-based wavelength selection algorithm is applied to the determination of glucose in two different biol...
Article
Full-text available
A solid-state, diffuse reflectance-based fiberoptic sensor is described for quantifying ammonia. This sensor is constructed by immobilizing chlorophenol red, a weak acid chromophoric indicator dye, in a microporous polypropylene membrane. A flow-injection analysis system is used to carry a 10-μL aliquot of the sample across the treated membrane. Am...
Article
Near-infrared calibration models are described for the measurement of total protein, albumin protein, globulin protein, triglycerides, cholesterol, urea, glucose, and lactate. Spectra are collected in triplicate over the 5000–4000 cm−1 spectral range with a 2.5 mm optical path length for 242 undiluted human serum samples. Calibration models are gen...
Article
Full-text available
A novel method is introduced for developing calibration models for the spectroscopic measurement of chemical concentrations in an aqueous environment. To demonstrate this matrix-enhanced calibration procedure, we developed calibration models to quantitate glucose and glutamine concentrations in an insect cell culture medium that is a complex mixtur...
Article
Spectroscopic methods are gaining in popularity in biotechnology because of their ability to deliver rapid, noninvasive measurements of the concentrations of multiple chemical species. Such measurements are particularly necessary for the implementation of control schemes for cell culture bioreactors. One of the major challenges to the development o...
Article
The validity of published reports claiming to have successfully measured in vivo blood glucose from noninvasive near-infrared spectra collected in a time-dependent manner is challenged on the basis of results obtained from a phantom glucose spectral data set. An in vitro model is used to simulate noninvasive human near-IR spectra. The phantom gluco...
Article
In vivo spectra from human subjects can be simulated with a phantom composed of different layers of water, fat and muscle tissue. All three components are necessary to simulate in vivo spectra collected over the combination spectral region (5000–4000 cm−1). Muscle tissue is not required, however, to accurately simulate overtone spectra (6600–5400 c...
Article
A multivariate calibration method is described in which Fourier transform near-infrared interferogram data are used to determine clinically relevant levels of glucose in an aqueous matrix of bovine serum albumin (BSA) and triacetin. BSA and triacetin are used to model the protein and triglycerides in blood, respectively, and are present in levels s...
Article
An absorbance based flow-through fiber-optic probe is developed for measurements of ammonia in neurochemical samples. The probe is constructed by trapping a small volume of an internal indicator solution between two sets of optical fibers. This indicator solution is separated from a flowing sample stream by a microporous gas permeable membrane. The...
Article
Full-text available
Multivariate calibration models are generated for glucose, glutamine, and asparagine on the basis of partial least-squares regression analysis of near-infrared single-beam spectra covering the 5000- 4000-cm-1(2000-2500-nm) spectral range. Models are constructed with both raw and digitally Fourier-filtered single-beam spectra. Model performance is e...
Article
Full-text available
Multivariate calibration models are developed that allow quantitative analysis of short segments of Fourier transform infrared (FT-IR) interferogram data. Before the interferogram segments are submitted to partial least-squares (PLS) regression analysis, a bandpass digital filter is applied to isolate a narrow range of frequencies that correspond t...
Article
A mathematical model is derived from the Stern±Volmer equation as a practical calibration function for various optical oxygen sensors based on quenching of ruthenium ¯uorescence. The model is simple and ¯exible, and is ideal for computing oxygen partial pressure from 0 to 760 Torr in gaseous samples, and 0 to 200 Torr in aqueous samples. Feasibilit...
Article
The purpose of this study was to develop non-invasive techniques to monitor the composition of cell culture media in insect cell bioreactors. Such a monitor could be used in conjunction with a fed-batch feeding scheme to ensure that cells are maintained in an optimal environment for growth and protein production. Glucose and glutamine concentration...
Article
A self-powered radioluminescent (RL) light source is evaluated as a means of supplying incident radiation for optical chemical sensors. The light source consists of 147Pm (a β-emitting radionuclide) and ZnS:Ag phosphor. Blue light (450 nm) is produced following the excitation of ZnS:Ag from β particles released by the 147Pm. The utility of this sou...

Citations

... CGM devices are minimally invasive techniques based on an implanted needle [6,7]. The article [8] identified 34 non-invasive and 31 minimally invasive glucose monitoring products, and it reviewed their regulatory, technological, and consumer features. Optical glucose measurement devices are emerging and promising techniques. ...