Analysis of Melamine and Cyanuric Acid by Liquid Chromatography with Diode Array Detection and Tandem Mass Spectrometry

Melamine and cyanuric acid are the compounds that caused the global incidences of kidney related disease to pets and infants in North America and China during the last two years. After a concerted research effort by U.S. laboratories, it was discovered that they were intentionally added in raw ingredients to pet foods or milk to increase nitrogen levels without providing protein. Melamine and cyanuric acid can easily combine by hydrogen bonding and produce a melamine-cyanurate complex that directly caused renal failure to pets and infants who consumed the tainted pet food or milk. Many analytical methods for the determination of melamine and cyanuric acid have been developed. In terms of sensitivity and validity, not all of the methods are useful. In the research described in this thesis, various analytical methods and techniques were explored to find better and easier methods for melamine and cyanuric acid analysis. In the first chapter, methods of enzyme immunoassay (EIA), high-performance liquid chromatography with diode array detection (HPLC-DAD), and ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS-MS) were studied for melamine analysis. The limits of detection (LOD) for EIA and HPLC-DAD were 0.02 and 0.1 µg/mL, respectively. The r2 values between the EIA and HPLC-DAD methods for melamine analysis of the fortified and originally contaminated samples were 0.997 and 0.989. The r2 values for UPLC-MS-MS with HPLC-DAD and with EIA were 0.957 and 0.949, respectively. The commercial melamine EIA kit used in this study proved to be a rapid and inexpensive alternative to the HPLC-DAD method to quantify melamine in pet foods. In the second chapter, pressurized liquid extraction (PLE) was evaluated and compared with typical extraction methods such as polytron and sonication. Recoveries obtained by the PLE method were significantly higher (P=0.05) than those of sonication and polytron methods for dry pet food samples. For the analysis of adulterated pet foods, PLE resulted in the highest melamine content followed by sonication and polytron. PLE provided the best extraction efficiency compared to sonication and polytron. In the third chapter, liquid chromatography with tandem mass spectrometry (LC-MS-MS) was used for determination of melamine and cyanuric acid using an alkaline pH aqueous extraction solvent (0.1 N ammonium hydroxide). When melamine cyanurate complex was fortified, alkaline extraction solvent yielded better recoveries than the acetonitrile/water (50/50) mixture, which is the most commonly used solvent for extracting melamine and cyanuric acid from various sample matrices. Since similar results were obtained from the adulterated pet food samples, it is assumed tht the adulterated samples were contaminated with melamine cyanurate complex rather than free melamine and cyanuric acid. Therefore, the method developed in this study is effective for the accurate determination of melamine and cyanuric acid

Book Review: The Customer Service Solution: Managing Emotions, Trust, and Control to Win Your Customer's Business by Sriram Dasu, Richard B. Chase

For the past few decades, improving quality of services has been recognized as a critical issue in many countries, especially in developed economies. Operations Management (hereafter OM), the field which has been mainly concerned with quality improvement, has been leveraging concepts from the old total quality management programs to new six sigma programs.  The focus has been on metrics such as speed of service, errors, and other process variables.  Despite growing evidence of the economic value of delivering memorable customer experiences, there has been very little research in OM on how to design service processes that influence customer’s perceptions during a service. The book “Customer Service Solution: Managing Emotions, Trust, and Control to Win Your Customers’ Business” offers very well organized and systemic approaches to design service operations that impact the experience. This book not only presents fundamental psychological principles that have a bearing on perceptions but also gives methods for designing service processes that are in accordance with these concepts. Examples from the industries such as e-commerce, sports, healthcare, hospitality, and financial services, ground these concepts and make them accessible to a wide audience. This book is written by two reseachers in service operations management, Sriram Dasu (Associate Professor) and Richard B. Chase (Justin Dart Professor Emeritus) at Marshall School of Business (University of Southern California, USC), and is the first book that systematically studies the dynamics of customer psychology in service operations. The book contains eight chapters. The first chapter begins by emphasizing how implicit outcomes in a service encounter are important. Service organizations have been focusing on improving explicit outcomes, and explicit outcomes are significant because they are measurable and they secure specific levels of the qualities in the service. However, the authors argue that explicit outcomes cannot solely guarantee the satisfaction of customers. The first chapter lays out a framework for shaping the implicit or psychological outcomes.  They identify six factors that shape consumer’s perceptions:  emotions, trust, control, sequence, duration, and attribution. Deeper descriptions of these six factors constitute the subsequent chapters. Chapter 2 and 3 contain discussions of what is important (customer’s emotions) and why it is important (for customer’s trust). Chapter 2 introduce the concept of ‘emotional intelligence,’ a capability of perceiving, assessing, and controlling emotion, and outline techniques for systematically deal with emotions. The authors emphasize the importance of designing customized emotional theme and offer various management tools to assess emotions customer experience at each stage of service. Chapter 3 illustrates the authors’ in-depth insight about the fundamental issue (information asymmetry and bounded rationality) about customer’s trust. This chapter provides several principles and techniques to build trust. In chapter 4, the authors claim that service providers need to maximize customer perceptions of being in control. This chapter identifies the types of control and how and when to share control based on required knowledge and significance of the service. Chapter 5 and 6 covers two traditional concepts of OM, sequencing service delivery and perceptions of time. Chapter 5 introduces a way to organize the sequence of events in order to enhance the experience during and after the service. Based on the finding of behavioral scientists they argue that memories are collection of snapshot and not movies.  Hence it is important to identify moments that matter.  The authors discuss the types of moments during a service that will impact the perception of customers. They conclude with a number of methods to design the sequence. In chapter 6, they remind us that what matters is perceived time not actual amount of time passed. Depending on whether the customers are waiting or engaged, the time is wasted or results in value. Providers may want to dilate the perception of value-added time while shrinking the perceptions of wasted.  They present factors that influence duration judgments and discuss how to frame service encounters in order for good times to be remembered and for bad time to be forgotten. Chapter 7 covers the issue about how customers make attributions of the outcomes when a service encounter is completed. Building on previous chapters, the authors propose methods for structuring the service encounters to enhance customers’ positive reactions instead of the negative.  Overall evaluation of the service, analysis of the cause of the outcomes – good or bad, and assignment of credit or blame are all subjective. Once again the authors present a range of theories that influence how subjects attribute blame or credit. They close the chapter with a collection of principles for managing attribution. Chapter 8 wraps up the book by presenting approaches for organizations to implement their ideas. They present two projects, “Improving the experience of online computer purchases” and “Improving interactions between nurses and chronic care patients” as examples of implementation plans. Overall, this book is very well written and all the chapters are constructed and linked in a sophisticated manner. It gradually translates fundamental concepts of behavioral sciences and social psychology to service system design principles. One of the interesting parts of this book is that there are many examples that were carefully selected to clarify the concepts and to make the readers reflect on their own experience. Therefore, once the readers get the idea they stick. This book is accessible and useful to both scholarly audience and practitioners. To scholars, the book provides great potential for the new avenue for study in multiple areas such as OM, Management Science, Marketing, and etc

Intrinsic Diophantine approximation on circles and spheres

We study Lagrange spectra arising from intrinsic Diophantine approximation of circles and spheres. More precisely, we consider three circles embedded in $\mathbb{R}^2$ or $\mathbb{R}^3$ and three spheres embedded in $\mathbb{R}^3$ or $\mathbb{R}^4$. We present a unified framework to connect the Lagrange spectra of these six spaces with the spectra of $\mathbb{R}$ and $\mathbb{C}$. Thanks to prior work of Asmus L.~Schmidt on the spectra of $\mathbb{R}$ and $\mathbb{C}$, we obtain as a corollary, for each of the six spectra, the smallest accumulation point and the initial discrete part leading up to it completely.Comment: 28 pages, 9 figure

BIRP: Bitcoin Information Retrieval Prediction Model Based on Multimodal Pattern Matching

Financial time series have historically been assumed to be a martingale process under the Random Walk hypothesis. Instead of making investment decisions using the raw prices alone, various multimodal pattern matching algorithms have been developed to help detect subtly hidden repeatable patterns within the financial market. Many of the chart-based pattern matching tools only retrieve similar past chart (PC) patterns given the current chart (CC) pattern, and leaves the entire interpretive and predictive analysis, thus ultimately the final investment decision, to the investors. In this paper, we propose an approach of ranking similar PC movements given the CC information and show that exploiting this as additional features improves the directional prediction capacity of our model. We apply our ranking and directional prediction modeling methodologies on Bitcoin due to its highly volatile prices that make it challenging to predict its future movements.Comment: 5 pages, 2 figures, KDD 2023 Machine Learning in Finance worksho

Kinetics and thermodynamics of metal‐binding to histone deacetylase 8

Histone deacetylase 8 (HDAC8) was originally classified as a Zn(II)‐dependent deacetylase on the basis of Zn(II)‐dependent HDAC8 activity in vitro and illumination of a Zn(II) bound to the active site. However, in vitro measurements demonstrated that HDAC8 has higher activity with a bound Fe(II) than Zn(II), although Fe(II)‐HDAC8 rapidly loses activity under aerobic conditions. These data suggest that in the cell HDAC8 could be activated by either Zn(II) or Fe(II). Here we detail the kinetics, thermodynamics, and selectivity of Zn(II) and Fe(II) binding to HDAC8. To this end, we have developed a fluorescence anisotropy assay using fluorescein‐labeled suberoylanilide hydroxamic acid (fl‐SAHA). fl‐SAHA binds specifically to metal‐bound HDAC8 with affinities comparable to SAHA. To measure the metal affinity of HDAC, metal binding was coupled to fl‐SAHA and assayed from the observed change in anisotropy. The metal KD values for HDAC8 are significantly different, ranging from picomolar to micromolar for Zn(II) and Fe(II), respectively. Unexpectedly, the Fe(II) and Zn(II) dissociation rate constants from HDAC8 are comparable, koff ∼0.0006 s−1, suggesting that the apparent association rate constant for Fe(II) is slow (∼3 × 103 M−1 s−1). Furthermore, monovalent cations (K+ or Na+) that bind to HDAC8 decrease the dissociation rate constant of Zn(II) by ≥100‐fold for K+ and ≥10‐fold for Na+, suggesting a possible mechanism for regulating metal exchange in vivo. The HDAC8 metal affinities are comparable to the readily exchangeable Zn(II) and Fe(II) concentrations in cells, consistent with either or both metal cofactors activating HDAC8.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110703/1/pro2623.pd

TB201: Comparison of the Efficacy of Sodium Acid Sulfate and Citric Acid Treatments in Reducing Acrylamide Formation in French Fries

Two acidulant food additives, sodium acid sulfate (SAS) and citric acid, were investigated for their effectiveness in reducing acrylamide formation in french fries. Acrylamide concentration was determined by gas chromatography-mass spectrometry (GC-MS) after cleanup of french fry extracts by passage through a C-18 column and derivitization by bromination. At a frying temperature of 180°C, both acidulants appeared ineffective, possibly due to the rapid rate of acrylamide formation, which surpassed the capacity of the acidulants to protonate acrylamide intermediates. At the lowest frying temperature tested (160°C), 3% SAS and 3% citric acid significantly (P \u3c 0.05) inhibited acrylamide formation as compared to the control. However, 3% SAS appeared to inhibit acrylamide formation more effectively than citric acid at 160°C, as well as at frying temperatures of 170 and 180°C. Our results indicate that acrylamide formation during frying can be reduced by treatment of potatoes with 3% SAS or citric acid, but SAS, a stronger acid with a lower pKa, is the more effective acidulant.https://digitalcommons.library.umaine.edu/aes_techbulletin/1006/thumbnail.jp

Development of a Catalytic Combustor with Thin-Honeycomb Substrate

Extended Abstract To obtain the most stable H2 yields in reforming systems, it is important to maintain a steady reaction temperature for catalytic reforming. When some parts of the catalytic combustor have hot spots with higher local temperatures, the combustor durability maybe affected or the reforming catalyst would be damaged, resulting in NOx generation Recently, many morphological studies on small-sized catalytic combustors, which are called microchannel catalytic combustors The objective this study is to optimize the catalytic combustor using a thin-honeycomb ceramic substrate, which is capable of providing a dimethyl ether (DME) reformer with a heat source required for endothermic reforming process. The catalytic combustor can also maintain a uniform temperature distribution about 500℃. The catalytic combustor was set the type of a fixed-bed flow reactor under atmospheric pressure. Pt/ γ -Al2O3 catalyst was coated on the cordierite substrate (600 cpsi). The experimental variables are the composition of multi-catalyst blocks, flow distributor, space velocity, excess air ratio, exit cross-section ratio of the burner, and type of fuel. From the results, it was found that the space velocity was selected at the range of 18,000-27,000 h -1 for stable combustion (RMSE(root mean square energy) <10). For the catalytic combustor using C3H8 as fuel, the design combination for the best performance with temperature uniformity and with no exhaust pollutants was the optimized Tshaped and SiC foam distributor, 3 catalyst blocks(lean coating on the front catalyst and rich coating on the rear of catalyst blocks), and 50% minimum cross-section ratio of the combustor outlet. For the catalytic combustor fueled with DME, the temperature variation on the surface of the catalytic combustor could be maintained within 17.6℃ compared to the reference temperature