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24 pages, 6523 KB

Open AccessReview

A Review of Research on the Intelligent Design of Ferrofluid Seals for Ultra-High Vacuum Applications

by Yingjian Zhen, Yang Si, Shouchun Liu, Wangxu Li, Shuai Wang, Mingyu Song and Zhengui Li

Processes 2026, 14(13), 2171; https://doi.org/10.3390/pr14132171 - 3 Jul 2026

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Ferrofluid sealing is an important non-contact sealing technology for ultra-high vacuum (UHV) equipment, but its reliability is affected by more than pressure-bearing capacity alone. This review shows that carrier-liquid evaporation, material outgassing, thermal degradation, magnetic-field distortion, and liquid-ring instability are the main factors limiting UHV ferrofluid seals. Multiphysics simulation and parametric optimization remain the most mature tools for analyzing magnetic-field distribution, pressure resistance, temperature rise, and structural deformation. Data-driven condition identification improves failure monitoring, whereas physics-informed neural networks, topology optimization, and multi-objective optimization are still emerging methods for low-sample prediction and collaborative design. Future studies should focus on low-vapor-pressure ferrofluids, bake-out compatibility, thermal management, lifetime prediction, and integrated model–data design frameworks. Full article

(This article belongs to the Section Chemical Processes and Systems)

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13 pages, 1689 KB

Open AccessArticle

OMNI: Gas Chromatograph Captures Seven Common PET Radiotracer Analytes in under 5 Minutes

by Camry Vonyae’ A’Keen, Jakub Mroz, Simon Kunta Joseph, Jairo Baquero, Melchor V. Cantorias and Patrick Carberry

Pharmaceuticals 2023, 16(11), 1623; https://doi.org/10.3390/ph16111623 - 17 Nov 2023

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Abstract

A novel gas chromatography method was developed using automatic injections to identify and quantify the amount of residual solvents or analytes in samples of fluorine-18 and carbon-11 radiopharmaceuticals. This approach evaluates seven analytes in less than 5 versus 13 min of acquisition time. The method additionally includes a 3 min bakeout to aid in the removal and carry-over of higher-boiling impurities. Chromatographic parameters such as column temperature, hold time, column pressure, flow rate, and split ratios were adjusted and optimized to analyze radioactive drug samples containing analytes which include methanol, ethanol, acetone, acetonitrile, triethylamine, N,N-dimethylformamide, and dimethyl sulfoxide. The relative standard deviation for each solvent was determined to be no greater than 1.6%. The method limit of detection (LOD) and limit of quantification (LOQ) were between 0.053 and 0.163 and 0.000 (5.791 × 10⁻⁶) and 0.520 mg/mL, respectively. This GC technique, using flame ionization detection (FID), was validated and is currently employed for the routine quality control of all approved IND and RDRC PET radiopharmaceuticals at our center. Full article

(This article belongs to the Topic Pharmaceutical and Biomedical Applications in Separation Techniques: Recent Trends and Developments)

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20 pages, 6364 KB

Open AccessArticle

Analyzing the Bake-Out Effect in Winter for the Enhancement of Indoor Air Quality at New Apartments in UAE

by Naglaa Sami Abdelaziz Mahmoud and Chuloh Jung

Buildings 2023, 13(4), 846; https://doi.org/10.3390/buildings13040846 - 23 Mar 2023

Cited by 12 | Viewed by 6667

Abstract

Indoor air pollution has become a pressing issue in the United Arab Emirates (UAE) due to poor ventilation, inadequate airtightness, and using chemicals in building materials. Accordingly, the UAE is currently experiencing more cases of sick building syndrome (SBS) than any other country. This study aims to assess the effectiveness of the bake-out strategy in reducing indoor air pollutants in a new apartment building in the UAE. The study evaluated a reduction in toluene (C₇H₈), ethylbenzene (C₈H₁₀), xylene (C₈H₁₀), styrene (C₈H₈), and formaldehyde (HCHO) at room temperature and relative humidity. The airtight unit without winter bake-out had higher indoor concentrations of hazardous chemicals than the ventilated units, and the emission of dangerous substances increased with temperature. Moreover, harmful chemicals were only effectively reduced with ventilation times of at least seven days after the heating period. The release rate of contaminants after the bake-out was lower than before. The indoor concentration of hazardous chemicals was lower when bake-out and mechanical ventilation were combined, resulting in a reduction of 92.8% of HCHO. Furthermore, units with a certain amount of ventilation maintained a low indoor pollutant concentration, regardless of whether a bake-out was performed. Full article

(This article belongs to the Special Issue Healthy, Digital and Sustainable Buildings and Cities)

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12 pages, 5533 KB

Open AccessArticle

The Initial Oxidation of HfNiSn Half-Heusler Alloy by Oxygen and Water Vapor

by Oshrat Appel, Shai Cohen, Ofer Beeri, Yaniv Gelbstein and Shimon Zalkind

Materials 2021, 14(14), 3942; https://doi.org/10.3390/ma14143942 - 14 Jul 2021

Cited by 6 | Viewed by 2596

Abstract

The MNiSn (M = Ti, Zr, Hf) n-type semiconductor half-Heusler alloys are leading candidates for the use as highly efficient waste heat recovery devices at elevated temperatures. For practical applications, it is crucial to consider also the environmental stability of the alloys at working conditions, and therefore it is required to characterize and understand their oxidation behavior. This work is focused on studying the surface composition and the initial oxidation of HfNiSn alloy by oxygen and water vapor at room temperature and at 1000 K by utilizing X-ray photoelectron spectroscopy. During heating in vacuum, Sn segregated to the surface, creating a sub-nanometer overlayer. Exposing the surface to both oxygen and water vapor resulted mainly in Hf oxidation to HfO₂ and only minor oxidation of Sn, in accordance with the oxide formation enthalpy of the components. The alloy was more susceptible to oxidation by water vapor compared to oxygen. Long exposure of HfNiSn and ZrNiSn samples to moderate water vapor pressure and temperature, during system bakeout, resulted also in a formation of a thin SnO₂ overlayer. Some comparison to the oxidation of TiNiSn and ZrNiSn, previously reported, is given. Full article

(This article belongs to the Special Issue Surfaces of Metals and Alloys – Phenomena, Processes and Their Characterization)

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16 pages, 7664 KB

Open AccessArticle

Bake-Out Strategy Considering Energy Consumption for Improvement of Indoor Air Quality in Floor Heating Environments

by Seonghyun Park and Janghoo Seo

Int. J. Environ. Res. Public Health 2018, 15(12), 2720; https://doi.org/10.3390/ijerph15122720 - 3 Dec 2018

Cited by 3 | Viewed by 3681

Abstract

Improved quality of life has led to a growing demand for better indoor air quality (IAQ). Buildings are becoming more airtight and insulated in order to minimize energy consumption. The importance of both energy conservation and IAQ improvement has been recognized and addressed by many studies. Bake-out is the process of using indoor heating to remove volatile compounds present in building materials and furnishings so that they can be vented out into the atmosphere. Indiscriminate use of heating to increase the surface temperature of materials during this process can result in significant loss of energy. Therefore, energy-efficient bake-out should be performed by considering both the floor temperature and the emission amount of pollutants. This study aims to investigate an effective and economical bake-out implementation strategy via experimentation and computational fluid dynamics analysis. The results showed weak direct correlation between the heating energy consumption and the amount of pollutants emitted. The study also highlights the passive option of installing sorptive building materials for improving IAQ economically. Full article

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9 pages, 4573 KB

Open AccessArticle

Optimum Installation of Sorptive Building Materials Using Contribution Ratio of Pollution Source for Improvement of Indoor Air Quality

by Seonghyun Park and Janghoo Seo

Int. J. Environ. Res. Public Health 2016, 13(4), 396; https://doi.org/10.3390/ijerph13040396 - 1 Apr 2016

Cited by 6 | Viewed by 4146

Abstract

Reinforcing the insulation and airtightness of buildings and the use of building materials containing new chemical substances have caused indoor air quality problems. Use of sorptive building materials along with removal of pollutants, constant ventilation, bake-out, etc. are gaining attention in Korea and Japan as methods for improving such indoor air quality problems. On the other hand, sorptive building materials are considered a passive method of reducing the concentration of pollutants, and their application should be reviewed in the early stages. Thus, in this research, activated carbon was prepared as a sorptive building material. Then, computational fluid dynamics (CFD) was conducted, and a method for optimal installation of sorptive building materials was derived according to the indoor environment using the contribution ratio of pollution source (CRP) index. The results show that a method for optimal installation of sorptive building materials can be derived by predicting the contribution ratio of pollutant sources according to the CRP index. Full article

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