Basant Giri

Evaluation of secondary metabolites, antioxidant activity, and color parameters of Nepali wines

Abstract We evaluated the quality of wines produced in Nepal in terms of phenolic, flavonoid, anthocyanin and tannin content, antioxidant capacity, and color parameters using spectrophotometric methods. The total phenolic content, total flavonoid content, and total antioxidant activities in Nepali wines ranged from 85.5 to 960.0 (mean = 360.5 ± 268.7) mg/L GAE, 40.9–551.3 (mean = 188.9 ± 161.5) mg/L QE, and 66.6–905.0 (mean = 332.8 ± 296.5) mg/L AAE, respectively. These parameters were significantly higher in red wines compared to white wines. The phenolic and flavonoid content showed strong correlation with each other as well as with antioxidant activities. Additional parameters measured included various color parameters and carbohydrates. The wine color showed strong correlation with phenol, flavonoid, and antioxidant activity, whereas this correlation was not significant with anthocyanin content. Multivariate analysis was carried out to better describe and discriminate the wine samples. Finally, we compared Nepali wines with wines from other countries.

Status of chemistry lab safety in Nepal.

Chemistry labs can become a dangerous environment for students as the lab exercises involve hazardous chemicals, glassware, and equipment. Approximately one hundred thousand students take chemistry laboratory classes annually in Nepal. We conducted a survey on chemical lab safety issues across Nepal. In this paper, we assess the safety policy and equipment, protocols and procedures followed, and waste disposal in chemistry teaching labs. Significant population of the respondents believed that there is no monitoring of the lab safety in their lab (p<0.001). Even though many labs do not allow food and beverages inside lab and have first aid kits, they lack some basic safety equipment. There is no institutional mechanism to dispose lab waste and chemical waste is disposed haphazardly. Majority of the respondents believed that the safety training should be a part of educational training (p = 0.001) and they would benefit from short course and/or workshop on lab safety (p<0.001).

Introduction to Microfluidics

This first chapter of Laboratory Methods in Microfluidics introduces microfluidics including fundamental features, advantages, and examples of commercial applications. The second part of the chapter includes a brief description of frequently used that may help to explain microfluidic phenomenon and the principles including laminar flow, electrokinetic flow, and separation resolution. Equations are given and described when necessary. In addition, some questions are listed that can be given for students assessment. The references provided at the end of the chapter may be used for further reading material.

Fabrication of a Glass Microfluidic Device

This chapter provides a step-by-step procedure for the fabrication of a microfluidic device using borosilicate glass as a substrate. Background information given at the start of the chapter highlights the advantages of glass substrate over other substrates and outlines the photolithographic method of fabrication. Subsequent topics cover design of the device, chemicals and materials required, and hazards associated with this experiment. The experimental section includes detailed steps for photolithography, chemical wet etching, and bonding procedures. Instructions are also provided for the evaluation of the prepared chip and tips for writing a lab report. Additional notes that may help instructors and students are also given. The included assessment questions can help determine students’ knowledge of the experiment. References at the end of the chapter may be helpful for further reading.

Acid–Base Titrations on Paper

This chapter gives experimental details of acid–base titration on a paper-based analytical device. Titrations including acid–base are widely practiced in classrooms. The experiment given in this chapter does not require glass burettes and pipets for titration. First, a general background of acid–base experiment is given, then topics related to design of the paper microfluidic device, chemicals and materials required, and the hazards associated with this experiment are covered. The experimental section includes a step-by-step procedure for device fabrication using wax printing, solution preparation, and performing titration. Additional notes that may help instructors and students are also highlighted. Assessment questions are included in addition to references at the end of the chapter for further reading.

A Simple Experiment for the Study of Droplet Microfluidics

This chapter describes an experiment to observe and study droplet generation and characterization in a microfluidic device. The chapter starts by giving background information on droplet microfluidics including its applications. The following sections cover topics related to the design of a PDMS microfluidic device, the chemicals and materials required, and the hazards associated with this experiment. The experimental section includes step-by-step procedure for device fabrication, droplet generation, and image quantitation and analysis. Additional notes that may help instructors and students are also highlighted. Assessment questions will be helpful to judge students knowledge on the experiment. References at the end of the chapter may be helpful for further reading.

Protein Immobilization on a Glass Microfluidic Channel

This chapter describes an experiment for immobilizing protein molecules on a glass microfluidic device fabricated on glass substrate. In this experiment, the glass surface is derivatized for covalent attachment of proteins. The chapter begins with a brief introduction of protein immobilization on solid surfaces and methods of attachment and discusses covalent immobilization using (3-aminopropyl)triethoxysilane and glutaraldehyde. The following sections cover topics related to the design of the paper microfluidic device, the chemicals and materials required, and the hazards associated with this experiment. The experimental section includes a step-by-step procedure for glass surface modification, data collection, and image analysis. Additional notes for instructors and students are also highlighted in addition to assessment questions to judge students’ knowledge of this experiment and references for further reading.

Analysis of a Mixture of Paracetamol and 4-Aminophenol in a Paper-Based Microfluidic Device

This chapter describes an electrochemical detection method on a paper device. First, a mixture of paracetamol (PA) and its degradation product 4-aminophenol (4-AP) is chromatographically separated and then detected as analyte on the same device. General information on measuring 4-AP in PA samples and a description of electrochemical detection on paper are provided in the background section. The following sections cover topics related to the design of a paper microfluidic device, the chemicals and materials required, and the hazards associated with this experiment. The experimental section includes a step-by-step procedure for device fabrication and electrochemical measurements. Additional notes that may help instructors and students are also highlighted in addition to assessment questions to determine students’ knowledge and understanding of the experiment. The references at the end of the chapter may be helpful for further reading.

Quantitative Determination of Total Amino Acids in Tea Using Paper Microfluidics and a Smartphone

Tea is the most popular manufactured drink consumed globally. Among the many chemicals present in tea extract are amino acids. This chapter describes a simple method to determine the amount of total free amino acids in tea leaves. The method is based on the ninhydrin test on a paper microfluidic device. The chapter starts with background information on the ninhydrin method and smartphone-based determination of the signal. Subsequent sections cover topics related to the design of a paper microfluidic device, the chemicals and materials required, and the hazards associated with this experiment. The experimental section includes a step-by-step procedure for device fabrication using wax pen and colorimetric determination of amino acids. Additional notes for instructors and students are also highlighted as well as assessment questions. References at the end of the chapter may be helpful for further reading.

Fabrication and Testing of a PDMS Microchip

Polymeric materials are emerging as popular substrates for microfluidic devices. The polydimethylsiloxane (PDMS) is one of the polymers used to make this type of device. This chapter gives experimental details for fabricating PDMS microchips. Instructions are also provided on how to observe laminar flow inside the channel by flowing two dyes and recording using a smartphone. Chemicals and materials required for the experiment and safety issues for the experiment are also provided. Additional notes that may help instructors and students are also highlighted. Assessment questions can help determine students’ knowledge of the experiment. References at the end of the chapter may be helpful for further reading.