Chemical Analysis Research Articles

Introducing regression discontinuity design to applied linguistics

Abstract This report presents regression discontinuity design (RDD) as a powerful analytical tool for use in applied linguistics showcased through our study of the impact of Japanese government study-abroad (SA) scholarships. RDD enables the estimation of causal effects in scenarios where a true experiment is not feasible by exploiting a naturally occurring cutoff point for treatment assignment. Because RDD may be novel to most readers in applied linguistics, this report provides a detailed step-by-step explanation of the standard RDD procedures our study exemplifies. The results section is crafted to reflect the conventional presentation style of RDD findings. Furthermore, the report’s concluding segment suggests scenarios within SA-related language learning research that could benefit from RDD application by enhancing the nuanced and precise interpretation of data in applied linguistics contexts.

Non‐destructive quantitative analysis of melt inclusions in extraterrestrial samples: Case study of chassignite via nanoscale X‐ray computed tomography

AbstractEstimation of the composition of planetary rocks and minerals is crucial for understanding their formation processes. In this study, we present the application of X‐ray nano‐computed tomography (nano‐XCT) for non‐destructive three‐dimensional (3‐D) phase analysis and estimation of phase abundances in rare Martian meteorite samples, specifically chassignite Northwest Africa (NWA) 2737. We determined the most suitable laser power for minimizing artifacts and maximizing phase contrast. By utilizing nano‐XCT, we successfully identified and segmented primary phases in the bulk meteorite sample. Additionally, we were able to locate and segment crystallized silicate melt inclusions within the meteorite. The phase abundances in bulk NWA 2737 and within melt inclusions calculated using nano‐XCT were in good agreement with previous studies that used thin section calculations, demonstrating the reliability of nano‐XCT as a non‐destructive alternative for estimating bulk phase abundances in rare samples. This study develops a benchmarking protocol and demonstrates the efficacy of nano‐XCT as a non‐destructive technique for generating an overview of phase distribution and assemblages of melt inclusions within rare samples. Future research can benefit from combining non‐destructive 3‐D phase assemblage estimations with non‐destructive 3‐D chemical analysis techniques to achieve a fully non‐destructive parental magma composition estimation of rare cumulate samples.

Using Geochemical Tracers to Determine Seasonal Inputs of Freshwater to a Coastal Estuary: Biscayne Bay, FL

Biscayne Bay is a coastal estuary that historically relied on rainfall and groundwater inputs from the karst Biscayne aquifer. The construction of major canals along the coastline has released point-source freshwater inputs into the bay, detrimentally affecting the Bay’s ecosystem balance. This project investigates the proportional inputs of freshwater between the wet and dry seasons in Deering Estate, adjacent to Biscayne Bay. The objective of this project was accomplished by analyzing the water chemistry of the bay using naturally occurring geochemical tracers. Water sampling occurred from May to August (wet season 2022) and January to March (dry season 2023); at an inland freshwater spring and on Biscayne Bay. Water samples were analyzed for δ18O and δ2H values, and Sr2+/Ca2+ ratios as geochemical tracers. The highest and lowest salinity values observed in the wet and dry seasons, at both the freshwater spring and Biscayne Bay sites, were before and after a major rain event, respectively. The chemical analysis supports that rain is the dominant source of freshwater input into the bay at our sampling location, and the freshwater spring is dominated by groundwater and canal water during the wet season. During the dry season, groundwater and canal water are the dominant source for the sampling location in Biscayne Bay and the dominant source of freshwater input for the freshwater spring. However, all three endmembers contribute seasonally. Understanding freshwater inputs to this crucial estuary will provide important information for current restoration efforts of Biscayne Bay, specifically around the Deering Estate area.

Parotid duct sialolithiasis in three Caspian miniature horses

AbstractThree Caspian miniature horses, exhibiting facial swellings, were examined in Alborz province. Physical examinations denoted sialolithiasis in two patients, and arose suspicion of the same condition in the third patient. The sialoliths were removed using a transcutaneous surgical approach with standing sedation using xylazine (1 mg/kg, intravenously) and local anaesthesia with lidocaine (5–10 mL) in all three patients. In Case 1, multiple pieces of stone were excised from the left parotid duct using a transcutaneous approach. In Case 2, a single oval‐shaped stone (44 g) was excised from the right parotid duct with the same technique as mentioned above. Case 3 presented a 1‐g amorphous stone partially obstructing the right parotid duct, resulting in cyst formation on the right aspect of the face. Chemical analysis identified calcium carbonate as the primary component. Given the distribution of horses in Iran, accurate estimation of the frequency of sialolithiasis is quite challenging, and numerous cases are overlooked.

Adaptability and Interconnectedness in Latin American Innerburbs: An Assessment of the Public/Private Interface in Informal Settlements

An “Innerburb” is an urban structure that emerged between the 1950s and 1980s, settled in rural areas, and is considered the first periphery of the Latin American city. This structure results from socio-spatial and territorial evolutionary processes, constituting the pinnacle of informal evolution. However, despite offering a comprehensive perspective on the informal problem, innerburbs have been scarcely reviewed in the literature. This article explores the Latin American innerburb by adopting as a method a comparative study of the public/private interface in the cases of San Cosme in Lima, Villa Rodolfo Ricciardelli in Buenos Aires and Vila Heliopolis in São Paulo, evaluating their adaptation and interconnection with the city through morphological indicators, using morphological mapping through satellite images as an analytical tool, and using Space Syntax as a topological approach in the analysis of connectivity and visibility indicators. The objective of the research is the detection of morphological patterns that alter the functioning of the public/private interface in innerburbs. The results show that the existence of impermeable facades, the lack of public spaces and the illegal appropriation in the development of informal practices are transgressive adaptability patterns at the micro-scale that affect the interface, drastically limiting the interconnection between the innerburb and the formal fabric, restricting its morphological openness and affecting the development of socioeconomic activities. As a discussion and conclusion, corrective measures for progressive improvement in innerburbs are established, focusing on the adaptability of housing and road space as a means of interconnection between the innerburb and the city.

Evaluation of long-term properties and life cycle assessment of alkali-activated concrete with varying fiber inclusions

The potential for using alkali-activated concrete (AAC) as a sustainable substitute for Portland cement (PC) concrete is a topic of ongoing research interest. The uncertainties in the raw material composition, the reportedly low tensile strength of AAC, and the lack of relevant standard codes of practice further inhibit wider industrial usage of AACs. Fiber inclusions reportedly enhance the tensile properties of traditional PC concrete. However, there is no long-term data available for fiber-reinforced alkali-activated concrete (FRAAC) mixtures. Hence, the present study is aimed at investigating the long-term mechanical properties of ambient-cured FRAAC with GGBS as the sole precursor. Four different types of fibers, viz., steel (SF), polyvinyl alcohol (PVAF), polypropylene (PPF) and glass (GF) are used in this research as reinforcements in AAC. Tests for compressive strength (fc′), splitting tensile strength (fsp) and flexural strength (fr) are conducted for FRAAC containing varying fiber contents of 0.1–0.3%. The findings demonstrated that fiber additions do not have any noticeable influence on the compressive strength of AAC. However, relative to the plain mix, the fsp and fr of FRAACs were enhanced by up to 32% and 29%, respectively. The formation of the hardened calcium aluminosilicate matrix and evolution of the fiber-matrix bonding over time was evident from the scanning electron microscopy (SEM) images. The related molecular bonds over a period of 7-d to 360-d was identified through mineralogical and chemical analyses. Furthermore, to validate its environmental sustainability, life cycle assessments were conducted. The AACs exhibited at least 43% lesser impacts than PC concrete on the ecosystem. FRAACs had only slightly higher (≤ 7% increase across all fiber types) impacts than plain AAC.

Manufacturing of TiO2, Al2O3 and Y2O3 Ceramic Nanotubes for Application as Electrodes for Printable Electrochemical Sensors

Manufacturing of TiO2, Al2O3 and Y2O3 Ceramic Nanotubes for Application as Electrodes for Printable Electrochemical Sensors

From laboratory to industrial use: Understanding process variation during enzymatic protein hydrolysis with dry film fourier-transform infrared spectroscopy

Industries are continuously looking for dedicated sensor solutions for evaluating the chemical composition of products that can provide valuable insights into process control, process optimization, and product quality. A rapid and robust analytical method, Fourier-Transform Infrared (FTIR) spectroscopy, holds significant potential in this regard as it provides detailed compositional values of food nutrients. The main aim of the present study was to use dry film FTIR spectroscopy as an analytical tool to characterize products from an industrial enzymatic protein hydrolysis process and link this to understand industrial process variations. For this purpose, 463 protein hydrolysate samples were obtained from an industrial enzymatic protein hydrolysis plant. In the same period, systematic variations in process parameters such as raw material composition, enzyme type, and water addition, were performed. All samples were analyzed using dry film FTIR spectroscopy. Two subsets containing 200 and 68 hydrolysate samples were chosen for measuring average molecular weight (AMW) and collagen content respectively, providing reference data for constructing calibration models based on partial least squares regression (PLSR). The percentage of low molecular weight constituents was derived from the molecular weight distribution of size exclusion chromatograms of protein hydrolysates and also used in the modeling. Calibration models for the prediction of AMW, low molecular weight constituents, and collagen content were obtained with a good fit and lower estimation errors. Principal component analysis (PCA) of protein hydrolysates' FTIR spectra effectively differentiated process variations (enzyme types and raw materials) without extensive reference analysis. One-factor analysis of variance (ANOVA) tests was used to observe the impact of process variation on product quality. FTIR proved to be a sensitive method for liquid protein analysis and process control with a significant potential in process optimization approaches. To the authors’ knowledge, this is the first time dry film FTIR spectroscopy has been used to evaluate an industrial bioprocess with designed process variations.

Attention towards chemistry agnostic and explainable battery lifetime prediction

Predicting and monitoring battery life early and across chemistries is a significant challenge due to the plethora of degradation paths, form factors, and electrochemical testing protocols. Existing models typically translate poorly across different electrode, electrolyte, and additive materials, mostly require a fixed number of cycles, and are limited to a single discharge protocol. Here, an attention-based recurrent algorithm for neural analysis (ARCANA) architecture is developed and trained on an ultra-large, proprietary dataset from BASF and a large Li-ion dataset gathered from literature across the globe. ARCANA generalizes well across this diverse set of chemistries, electrolyte formulations, battery designs, and cycling protocols and thus allows for an extraction of data-driven knowledge of the degradation mechanisms. The model’s adaptability is further demonstrated through fine-tuning on Na-ion batteries. ARCANA advances the frontier of large-scale time series models in analytical chemistry beyond textual data and holds the potential to significantly accelerate discovery-oriented battery research endeavors.

Technical and Enviro-economic Analysis of a 0.78 kWp PV System

Aim: To determine the technical, economic and environmental performance analysis of an installed PV backup system. Study Design: To attain this goal, analysis were performed using a freely available PVSyst 6.7.0 software tool. Economic evaluation was performed using respective present worth of individual component prices. Environmental performance comparison is made between the PV system and diesel generator when each is used as an independent backup system. Input in-situ measured data were determined, measured and keyed into the tool. Place and Duration of Study: The system is installed in an institutional building in a tropical climatic zone with coordinates 0.42 N and 35.03 E. The system was studied for a period of one year where data was collected and recorded for techno-enviroeconomic analysis. Methodology: The system consists of four PV modules rated at 0.78 KWp, charge controller and an inverter unit and battery bank, and is utilized as a power backup system to supply electricity whenever power failure occurs, which is frequent and real in Kenya. The techno-enviroeconomic performances analysis of the system were evaluated using the PVSyst software, a freely available design and analytical tool, where input data were measured and recorded at the site. Results: The performance analysis of the system showed that PV array efficiency of 13.24%, FF of 0.68, CF of 21.23%, and PR of 73.63% and generated electrical energy of 1092 kWh/year. The LCOE of PV electricity was 0.059 $/kWh, while total saving of CO2 emission in tons of CO2 was 9.0 tCO2 with LCE value of 331 gCO2/ kWh. Conclusion: Techno- enviroeconomic performance results of the studied PV system show that the system can contribute significantly to the mitigation of CO2 emission. This work also could be helpful for consumers and policy makers in the choice of renewable based or fossil based backup generation systems.

Enhancing workplace spirituality for higher education academicians through human resource practices

PurposeThis study investigates how human resource training and development (HRTD) shapes workplace spirituality in higher education. It delves into key factors impacting spirituality among academics, such as colleague support and e-learning initiatives. Through analytical tools like percentage analysis and Garret ranking, it divides workplace spirituality in academia, exploring the HR strategies that induce it.Design/methodology/approach(a) Type of research – Descriptive research (b) Area of research – The present study is taken up by the academicians as a respondent in selected colleges in Salem district. (c) Sampling technique – Simple random method was adopted. (d) Sources of data collection – The study comprises mixed data method that both types of data were adopted. (i) Primary data – Researcher conducted data by selecting a representative sample of the teaching faculties from various institutions employed in higher education in Salem. (ii) Secondary data – It is mostly gathered through content found on websites. (e) Method of data collection – Structured questionnaires were employed in this research to acquire the data needed for the investigation. Every item it is rated through five-point scale of with 1 denoting “Strongly Agree” to “Strongly Disagree,” this includes questions about the job, coworkers, seniors and training. (f) Research tools used – Descriptive statistics, Friedman test and Garret ranking.FindingsFindings highlight the significance of encouraging colleagues, workplace development and online learning in fostering workplace spirituality. Faculty encouragement emerges as the most impactful HR practice, while development initiatives improve the reputation of training for new aspects. Notably, online training significantly affects workplace spirituality, increasing the influence of cultural training.Research limitations/implicationsImplications for future research arise, suggesting potential models for studying workplace spirituality in academia and sparking curiosity about the connection between HR practices and spirituality.Practical implicationsFrom a practical viewpoint, the study offers actionable insights for authorities to improve workplace spirituality by supporting colleagues and emphasizing growth strategies. It outlines clear steps for organizations to create more spiritually enriching work environments.Social implicationsSocially, the study advocates for healthier work cultures that impact society's perspective on work–life balance and employee well-being. It promotes positive work environments that benefit both individuals and society.Originality/valueThis paper's originality lies in its focus on how HRTD contributes to workplace spirituality in higher education. It emphasizes supporting colleagues, fostering growth and utilizing e-learning, offering unique insights into spirituality at work. The methodology, using structured questionnaires and statistical analysis among faculty, provides a distinct approach to studying this area.

Holding the harasser responsible: Implications of identifying sexual harassment that includes abuse of power and quid pro quo elements as sexual corruption

AbstractThis article argues that a perpetrator‐based definition of sexual harassment that highlights corrupt aspects of sexual harassment may contribute to a shift in focus from the experience of the harassed, to the actions of the harasser. This argument is based on an analysis of testimonies of sexual harassment from the #metoo call by the Swedish police in 2017, which reference abuse of power and quid pro quo elements. By introducing the recently developed analytical framework of ‘sexual corruption’, we show how a perpetrator‐based definition of sexual harassment may contribute to attributing responsibility to harassers. Identifying sexual harassment that includes the abuse of power and quid pro quo elements as corruption centers on the role of the abuse of power and, thus, the responsibility of the person abusing their position of power. Moreover, this shift bypasses discussions of whether or not the situation was experienced as ‘unwelcome’ by the harassed, the severity of the act, and questions of coercion and consent. Identifying instances of sexual harassment that include the abuse of power and quid pro quo elements as corruption also closes off attempts to portray it in terms of ‘jokes’ or banter, which is common in the police context. The article contributes with analytical tools that enable a shift from tracing the experience of the harassed to centering on the actions and responsibility of the harasser.

Static and dynamic strength properties of highly structured clay-rich diatomite in Shengzhou, China

Diatomite is a widespread geological substance found in coastal and lake areas worldwide. Although diatomites are increasingly used in geotechnical engineering construction, a significant knowledge gap exists regarding their mechanical responses to static and dynamic loadings, particularly in high-speed railway projects. This study investigates the static and dynamic behaviors of diatomites through extensive experiments, considering both natural and remolded states. It focuses on representative diatomite specimens obtained from the Shengzhou region in China, an area intersected by the Hang-Shao-Tai high-speed railway. The results of uniaxial compression and undrained triaxial shear tests show that the structural degradation of diatomite significantly impacts its stress-strain responses, failure patterns, and mechanical parameters under static and dynamic loading conditions. The structural effects of natural diatomite tend to degrade as the confining pressure level increases, resulting in corresponding changes in its mechanical parameters. Undrained triaxial shear tests conducted on natural diatomite reveal that the inclinations of the shear band closely correspond to those predicted by the Mohr-Coulomb solution. Additionally, we present a modified hyperbolic-type model to evaluate the damping ratio of diatomites. Furthermore, a power-law model based on Hardin's formula was used to predict the maximum shear modulus of diatomites under varying stress levels and void ratios. Microstructural and chemical analyses were conducted using scanning electron microscopy and X-ray diffraction to gain insights into the observed structural effects at the microscale.

Effect of Fiber and Insect Powder Addition on Selected Organoleptic and Nutritional Characteristics of Gluten-Free Bread

A wide range of gluten-free bakery products are already available on the market. However, they often have a low proportion of fiber and inferior sensory properties when compared to classic baked goods. The aim of this work was to evaluate the influence of the addition of different types of fiber and insect powder on selected organoleptic and nutritional properties of gluten-free pieces of bread and to reformulate a recipe for gluten-free bread. Twenty experimental samples were prepared with different types and percentages of fiber, either alone or in combination. Sensory analysis, instrumental texture analysis, and chemical analyses, including predicted glycemic index, were carried out. A total of 16 of the 24 fiber-enriched samples received an average or slightly above-average rating. The samples containing the fiber mixture without insect powder and the sample containing 9% flaxseed performed best in the overall evaluation. The combination of different types of plant fibers simultaneously with the incorporation of insect powder in a low concentration appears to be advantageous, both from the viewpoint of sensory acceptability and also from the viewpoint of the potential for increasing the polyphenol content and antioxidant capacity. This study lists the sensorially acceptable range of fiber concentrations, which can be a guide for the bakery industry.

Co-liquefaction of α-cellulose and phycocyanin: A preliminary study

Hydrothermal liquefaction (HTL) is an efficient technology for converting biomass to platform compounds. It has great potential for reducing the dependence on fossil fuels. The HTL of waste biomass has been extensively studied in recent years due to both its environmental and economic benefits. However, most woody waste contains a large amount of cellulose, and it is difficult to be sufficiently decomposed to valuable chemicals. Phycocyanin, a key component of algae, is easily degraded under high-temperature liquefaction conditions. In this work, focusing on bio-oil generation properties, the co-liquefaction characteristics and synergistic mechanisms of α-cellulose and phycocyanin were explored. The findings revealed a maximum bio-oil yield of 33.1 wt% under the optimal conditions (300 °C for 40 min), with a notable positive synergistic effect of 13.5 wt%. Chemical composition analysis indicated distinct compositional differences between the bio-oils derived from individual and dual feedstock. The amounts of pyridine and pyrimidine compounds increased due to the enhanced co-liquefaction. The results also highlighted the influence of temperature on the degree of conversion and product distribution. Finally, preliminary chemical reaction pathway was elucidated, underscoring the potential of integrating microalgae and woody biomass for enhanced bio-oil production.

AN ANALYSIS OF MICRO-NUTRIENTS COMPOSITION OF COCOYAM (COLOCASIAE ESCULENTA) AND SWEET POTATO (IPOMOEA BATATAS L) LEAVES IN MELON SOUP

The study ascertained the micro-nutrient composition of cocoyam and sweet potato leaves in melon soups. The study was conducted to identify vitamins and mineral composition in three types of melon soups. The instrument adopted for the study was laboratory analysis of food nutrients using official methods of Association of Official Analytical Chemists. The data for micro nutrients were collected in triplicates from the melon soups in the food analysis laboratory, raw triplicate values of each micro nutrient in the soups were collected and analyzed using ±SD and ANOVA statistics to test the hypotheses 1 – 4. The findings revealed that cocoyam and sweet potato leaves melon soups are as rich as fluted pumpkin leaf melon soup in micro nutrients, such as vitamin A (Iµ) 16.03: 16.80 while fluted pumpkin 19.88; vitamin C (mg) 26.30: 36.89 while fluted pumpkin 28.46; folic acid (mg) 33.44: 40.64 while fluted pumpkin 46.73 among others. For minerals- Na (mg) 29.80: 26.16 while fluted pumpkin 34.19; Fe (mg) 1.41: 1.60 while fluted pumpkin 1.24 K (mg) 36.08: 46.46 while fluted pumpkin 34.57; Ca (mg) 11.19: 8.10 while fluted pumpkin 5.88; Mg (mg) 4.62: 3.53 while fluted pumpkin 2.63 among others. The study also showed that there was a significant difference between the mean values of the micro-nutrients analysis. The study recommended that, the consumption of cocoyam and sweet potato leaves should be encouraged by families in the country, as well be made available in the open market same way the popular vegetables are sold such as fluted pumpkin (Ugu) leaf.

Enhancing Sensitivity and Selectivity in Pesticide Detection: A Review of Cutting-Edge Techniques.

The primary goal of our review was to systematically explore and compare the state-of-the-art methodologies employed in the detection of pesticides, a critical component of global food safety initiatives. New approach methods in the fields of luminescent nanosensors, chromatography, terahertz spectroscopy, and Raman spectroscopy are discussed as precise, rapid, and versatile strategies for pesticide detection in food items and agroecological samples. Luminescent nanosensors emerge as powerful tools, noted for their portability and unparalleled sensitivity and real-time monitoring capabilities. Liquid and gas chromatography coupled to spectroscopic detectors, stalwarts in the analytical chemistry field, are lauded for their precision, wide applicability, and validation in diverse regulatory environments. Terahertz spectroscopy offers unique advantages such as noninvasive testing, profound penetration depth, and bulk sample handling. Meanwhile, Raman spectroscopy stands out with its nondestructive nature, its ability to detect even trace amounts of pesticides, and its minimal requirement for sample preparation. While acknowledging the maturity and robustness of these techniques, our review underscores the importance of persistent innovation. These methodologies' significance extends beyond their present functions, highlighting their adaptability to meet ever-evolving challenges. Environ Toxicol Chem 2024;00:1-17. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Multipoint monitor of beer fermentation

This short communication is devoted to a fully-mechanized flow analysis system for the control of beer fermentation process. The developed system is based on microsolenoid flow controlling devices (valves and pumps) and a flow-through optoelectronic detector. All these components are powered and controlled by a Adruino-compatible microprocessor platform that creates an integrated, compact, and robust analytical tool. Multiplication of sample aspiration ports of the analytical system allows for simultaneous monitoring of several independently performed fermentation processes, as well as a single process at the different places of fermentation tank. To demonstrate its practical utility, the developed system has been applied for online and real-time monitoring of yeast propagation and distribution in beer worts in the course of various fermentation processes. Potentially, this flow analysis system can be easily expanded to the form of multianalyte monitor equipped with optoelectronic sensors and biosensors for the determination of other parameters and analytes.

Testing non-destructive spectrometric methods for the identification and distinction of archaeological pine wood tar and birch bark tar

Archaeological findings prove the appearance and use of birch bark tar since the Middle Palaeolithic. The production and use of birch bark tar and pine wood tar has overlapped since at least the late Neolithic, but probably for much longer. The reliable chemical identification of such archaeological tar residues can offer valuable insights into, for example, ancient technical complexity, trade and culture. In this context, the scarcity of these mainly organic residue findings in the archaeological record bears the need for non-destructive analytical tools. However, there is currently no systematic proposed way for this purpose. We aim here to verify the organic nature and test the reliability of the identification of archaeological pine wood tar and birch bark tar with a combination of SEM-EDS, FTIR microspectroscopy in reflectance mode and XRD. We examined a set of experimental adhesive replicas of pine tar and birch tar in pristine form, but also after a three-year-long weathering experiment. Additionally, we studied a set of archaeological samples, consisting of Mesolithic bone/antler points with adhering hafting residues, form the Dutch North Sea. This research shows that degradation negatively influences the reliable verification and identification of the organic residue constituents significantly. SEM-EDS as a starting point of analysis verifies the residue’s organic nature, but it cannot be used to identify birch or pine tar. XRD can identify crystalline additives in the adhesive mixture, like ochre and wax, as well as phases related to the artefact’s environment of burial and provenance. Micro-FTIR is also capable of verifying the organic matter of the residue constituents. The differentiation of birch and pine tars is hindered by vibrational modes occurring in neighbouring wavenumbers for both tars, and by the limited research on degradation markers indicative of thermal treatment to prove tar production. Until reference collections also account for degradation and include a wide variety of adhesives, results of FTIR collected in reflectance mode are best treated with some caution.

Dams trigger exponential population declines of migratory fish.

The impact of dams on global migratory fish stocks is a major challenge and remains seriously underestimated. China has initiated a dozen fish rescue programs for the dams on the Yangtze River, focusing on five flagship species-Chinese sturgeon, Chinese paddlefish, Yangtze sturgeon, Chinese sucker, and Coreius guichenoti. Despite 40 years of effort, these five fishes are on the verge of extinction. Here, we propose an analytical tool that includes a framework of fish migration taxonomy and six life cycle models, the concepts of invalid stock and the dam impact coefficient, and a simplified population model. We then clarify the migration patterns and life cycles of these fishes and show that the Yangtze dams have severely disrupted the life cycle integrity of these species, causing seven types of invalid stocks and their exponential population declines. Last, we discuss six scientific misjudgments underpinning the fish rescue programs and recommend reforms to China's fish rescue strategy.