Purge Method Research Articles

Purging frequency and number of purging methods as indicators of severity in bulimia nervosa: Interactive effects with binge eating episodes.

In the Diagnostic and Statistical Manual of Mental Disorders-5, severity of bulimia nervosa (BN) is defined by the frequency of purging behaviour. Previous research suggests the number of purging methods as an alternative rating. The current analysis investigated characteristics (sociodemographic and treatment-related variables, body mass index [BMI], eating disorder-specific and general psychopathology) of persons with BN as a function of purging frequency and number of purging methods in order to examine which approach might be better suited for indicating severity of BN. Two-hundred and sixty-one persons (98.5% female; mean age 25.2years, SD=9.41; mean BMI 22.0kg/m2, SD=3.79) with BN completed self-report questionnaires on eating disorder-specific and general psychopathology at admission to inpatient (n=214) or daypatient (n=47) treatment. Higher severity based on either purging frequency or number of purging methods tended to relate to lower BMI and higher eating disorder-specific and general psychopathology. In addition, binge-eating frequency differentially related to eating disorder-specific and general psychopathology as a function of severity groups. This study partially supports the utility of both purging frequency and the number of purging methods as indicators of severity in persons with BN. However, focussing only on purging behaviours may be short-sighted as it appears necessary to consider the number of binge-eating episodes as well when evaluating severity of BN.

Comprehensive analysis of recovery procedures for SO2-contaminated proton exchange membrane fuel cells

Proton exchange membrane fuel cells (PEMFCs) are critical in transitioning to a low-carbon future, especially in industries like heavy-duty transportation, maritime shipping, and aviation. However, the use of ambient air exposes Pt-based electrocatalysts to air contaminants, leading to performance loss and premature degradation. SO2 appears to be the most crucial air impurity for fuel cell operation due to the formation of strongly adsorbed S-containing species, like elemental S0 on the cathode Pt surface and a lack of self-recovery in pure air. This work evaluates the efficiency of potential cycling from 0.1 to 1.2 V and cathode purging with pure O2 for recovering PEMFC performance after 5 ppm SO2 exposure at 80 °C. Results indicate that SO2 contamination at higher operating current densities causes more pronounced loss in performance and electrochemical area as well as negatively affecting recovery. Both potential cycling and O2 purge methods show recovery efficiencies of up to 95 % for fuel cells contaminated at lower current densities (0.4 A cm-2) and 84 % at higher current densities (1.0 A cm-2). Interestingly, the end of test diagnostics further improved performance, reaching a recovery efficiency of 95-97 %. The findings suggest that while both recovery methods are effective, the O2 purge technique is more practical for field applications due to its simplicity and lack of need for auxiliary equipment. The study employs a segmented cell system to analyze localized performance variations and SO2 contamination impacts.

Optimization of cleaning process in semiconductor gas delivery system by computational fluid dynamics simulation

Purging specialty gas delivery systems in semiconductor industries are essential for ensuring worker safety and complying with stringent environmental regulations. The cleaning process impacts production costs due to the required resources and time. This study introduced and evaluated various purging methods, combining vacuum, vacuum with purge, pressurization, and pressure-gradient purge steps. Considering the density and viscosity of various specialty gases used in semiconductor manufacturing, such as gaseous NH3, HCl, WF6, and SiCl4, were selected as the representative specialty gases for the system. Considering the utilization of the semiconductor industries, ultra-high purity nitrogen was selected to clean all components of the gas delivery system, including gas channels, filters, pressure regulator and diaphragm valves. Efficiency was measured by monitoring residual gas concentration changes during different purge-step configurations, the number of purge configuration, and step durations. The dynamic behavior of specialty gases was analyzed based on geometric factors and chemical properties. Findings indicated that cleaning dead-end zones was particularly challenging and impacting overall system efficiency. Frequent purge with a short step time proved more effective in removing residual chemicals than the present conventional vacuum purge process with a continuous N2 supply. Employing a pressure gradient between the inlet and outlet enhanced cleaning efficiency. These insights provide valuable guidelines for optimizing purging processes to reduce cleaning time and resource consumption in semiconductor manufacturing.

Sulfur isotope analyses using 3× elemental analysis/isotope ratio mass spectrometry: Saving helium and energy while reducing analytical time and costs.

Helium (He) and energy shortages have caused price increases and reduced their availability. Using three combustion reactions per acquisition of carbon and nitrogen isotope ratios saves 50% He and energy during the elemental analysis/isotope ratio mass spectrometry (EA/IRMS). This approach needs to be tested for sulfur isotope (δ34S) analyses. A new method to measure δ34S in three sequential combustion reactions within one EA/IRMS acquisition was developed. The same material or blank samples could be used in the three reactions. After SO2 was used, a N2 purging method was employed to prolong the lifetime of the valves in the EA/IRMS interface. The 3×EA/IRMS was applied to measure δ34S in precious samples, such as Ag2S from acid-volatile and chromium-reducible sulfur extracted with a multiple-port setup. The 3×EA/IRMS-δ34S method was validated with replicate analyses of international reference materials and laboratory standards with a wide range of mineralogical compositions and δ34S values. The method provided a strategic advantage for the δ34S measurements of small precious samples (measured between blanks). The accuracy and precision of the 3×EA/IRMS values effectively matched those obtained using conventional EA/IRMS, with good agreement between the mean ± SD values and the recommended values with their uncertainties. Compared with the conventional EA/IRMS, the proposed method provides accurate and precise δ34S measurements of the sulfate and sulfide samples while saving approximately 50% of He, energy, SO2 reference gas, O2, analysis time, and cost. Notably, 3×EA/IRMS can provide up to three δ34S values unaffected by memory effects.

CLINICAL EFFICACY OF CD34 POSITIVE SELECTION EX‐VIVO PURGING DURING AUTOLOGOUS STEM CELL TRANSPLANTATION IN PERIPHERAL T CELL LYMPHOMA

Background: Autologous stem cell transplantation (ASCT) is the standard treatment for peripheral T-cell lymphomas (PTCLs). Strategies that reduce the relapse rate and treatment-related mortality are essential for successful ASCT. Because in vivo/in vitro purging methods using rituximab are not appropriate for T-cell lymphomas, an ex vivo CD34+ selective purging system using CliniMACS is the most reliable method to reduce autograft tumor cell contamination in these tumors. In the present study, we retrospectively analyzed the clinical outcomes of HDT/ASCT after ex vivo purging via the CD34+ selective method in T-cell NHL patients. Methods: We retrospectively investigated the influence of ex vivo purging with CD34+ selection to maximize the effects of ASCT. Of 67 consecutive PTCL patients, 32 and 35 underwent purged and unpurged ASCT. Results: The purged group had improved overall survival (OS), disease-free survival (DFS), and cumulative incidence of relapse (hazard ratio [HR] = 2.68, p = 0.016; HR = 3.97, p = 0.002; and HR = 3.65, p = 0.004, respectively), compared to the unpurged group. Prognostic factor analysis showed that unpurged ASCT, chromosomal abnormalities at initial diagnosis, high risk, and pre-ASCT disease status were associated with poor survival outcomes. Subgroup analysis demonstrated that purging was most appropriate for International Prognostic Index high-risk patients who underwent upfront ASCT (HR = 3.35 [OS] and = 6.59 [DFS]). In purged ASCT group, NK cell activity and the lymphocyte-to-monocyte ratio known as an independent prognostic factor were increased after ASCT with statistical significance; the lymphocyte-to-monocyte ratio (LMR) was significantly increased after ASCT in the purged group (mean difference = 1.484, 95% CI = 0.407–2.560; p = 0.009). Also, Engraftment was achieved in all patients with no need for unpurged autologous stem cell backup in purged group. There were no engraftment failures or differences in adverse events including of transplant-related viral infections between the two groups. The research was funded by: The research was funded by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF-2020R1G1A1099654). Keywords: Aggressive T-cell non-Hodgkin lymphoma, Stem Cell Transplant No conflicts of interests pertinent to the abstract.

Influence of oxygen, UV light and reactive dissolved organic matter on the photodemethylation and photoreduction of monomethylmercury in model freshwater

The key factors which affect the abiotic photodemethylation process of monomethylmercury (MMHg) in the freshwaters has remained unclear. Hence, this work aimed to better elucidate the abiotic photodemethylation pathway in a model freshwater. Anoxic and oxic conditions were implemented to investigate the simultaneous photodemethylation to Hg(II) and photoreduction to Hg(0). MMHg freshwater solution was irradiated through exposure to three wavelength ranges of full light (280–800 nm), without short UVB (305–800 nm), and visible light (400–800 nm). The kinetic experiments were performed following dissolved and gaseous Hg species concentrations (i.e., MMHg, iHg(II), Hg(0)). A comparison between two methods of post-irradiation purging and continuous-irradiation purging confirmed MMHg photodecomposition to Hg(0) is mainly induced by a first photodemethylation step to iHg(II) followed by a photoreduction step to Hg(0). Photodemethylation under full light extent normalized to absorbed radiation energy showed a higher rate constant in anoxic conditions at 18.0 ± 2.2 kJ−1 compared to oxic conditions at 4.5 ± 0.4 kJ−1. Moreover, photoreduction also increased up to four-fold under anoxic conditions. Normalized and wavelength-specific photodemethylation (Kpd) and photoreduction (Kpr) rate constants were also calculated for natural sunlight conditions to evaluate the role of each wavelength range. The relative ratio in wavelength-specific KPAR: Klong UVB+ UVA: K short UVB showed higher dependence on UV light for photoreduction at least ten-fold compared to photodemethylation, regardless of redox conditions. Both results using Reactive Oxygen Species (ROS) scavenging methods and Volatile Organic Compounds (VOC) measurements revealed the occurrence and production of low molecular weight (LMW) organic compounds that are as photoreactive intermediates responsible for MMHg photodemethylation and iHg(II) photoreduction in the dominant pathway. This study also supports the role of dissolved oxygen as an inhibitor for the photodemethylation pathways driven by LMW photosensitizers.

Super-conformal TiN thin film deposition by carrier pulse purge atomic layer deposition system: Chamber design optimization with computational fluid dynamics

Owing to the increase in demand for the shrinkage of semiconductor design rules and the advent of the three-dimensional structure of semiconductor devices, atomic layer deposition (ALD) has emerged as an attractive alternative to conventional chemical vapor deposition techniques. Although the development of precursors and characterization of ALD films have been widely studied, few studies have been conducted on the modification of ALD parameters and optimization of the ALD process. In this study, an advanced ALD titanium nitride (TiN) system was designed using a pumping and purging simulationBased on the simulation results, we adopted a carrier pulse purge method, where TiCl4 fed, purge N2, pulse purge N2, purge N2, NH3 fed, purge N2, pulse purge N2, and purge N2 were alternatively injected into the chamber in the ALD cycle. Compared to the conventional purge method, the carrier pulse purge method can reduce the ALD cycle time by 18.27% and yields a high-quality (high step coverage, 98 %) TiN film with lower electrical resistivity and chlorine impurity. This carrier pulse purge method can ultimately lead to improved throughput and productivity in the semiconductor industry by reducing the ALD cycle time.

Studies on the valveless scheme to produce high-frequency detonations with different purge methods

Producing high-frequency detonations is an important topic for pulse detonations which has received considerable attentions. The valveless scheme has been verified to be able to obtain high-frequency detonations more than 100 Hz. This work has been conducted to investigate the possibility to achieve a higher detonation frequency and clarify the limits of stable operations preliminarily for the valveless scheme with different purge methods. Oxygen, ethylene, and nitrogen or liquid water are utilized as oxidizer, fuel, and purge medium in the experiments while two injection configurations are employed. The maximum detonation frequencies of 180 Hz and 330 Hz have been achieved in stable operations for two different injection configurations when nitrogen is used as the purge gas. The ceiling frequency for stable detonations is 300 Hz if nitrogen is replaced by liquid water, which indicates that water vapor is capable to create an efficient buffer zone to ensure stable operations. The results imply that the injection configuration also has a great impact on the ceiling stable detonation frequency. Three operating modes have been observed in this study, i.e., a stable detonation mode, an unstable detonation mode, and a deflagration mode. In the unstable mode, failure of detonation initiation occurs frequently and one interesting phenomenon is that the detonation frequency is reduced by half exactly when insufficient filling happens. The supply pressure ratios of oxidizer to fuel and purge to fuel are obtained for different operating modes when the purge method is changed. Furthermore, the equivalence ratios have been also studied for different operating modes which reveals that the range will change when different purge methods and injection configurations are employed. According to the equivalence ratio and the mass flow rates, an equivalent volume fraction of oxygen is defined and its range for the stable detonation mode is clarified.

Quantification of N and C cycling during aerobic composting, including automated direct measurement of N2, N2O, NO, NH3, CO2 and CH4 emissions

Closing the carbon (C) and nitrogen (N) balance has yet to be achieved in aerobic bioprocess due to current methodological drawbacks in the frequency of sampling and detection and the challenge in direct measurement of instantaneous N2 emission. To address this issue, a novel system was developed enabling simultaneous and online determination of gaseous C and N species (N2, N2O, NO, NH3, CO2 and CH4) from aerobic composting at a high frequency of 120 times·d−1. A helium‑oxygen gas mixture was used to replace the air in the system to enable direct measurement of N2 emission, and three different gas exchange methods were assessed in their ability to minimize atmospheric background N2: 1) the N2-free gas purging method; 2) one cycle of the evacuation-refilling procedure; 3) one cycle of evacuating and refilling followed by N2-free gas purging. Method 3 was demonstrated as an optimum N2-removal method, and background N2 concentrations decreased to ~66 μmol·mol−1 within 11.6 h. During the N2-free gas purging period, low temperature incubation at 15 °C reduced CO2, CH4, NO, N2O and NH3 losses by 80.5 %, 41-fold, 10-fold, 11,403-fold and 61.4 %, respectively, compared with incubation at 30 °C. Therefore, a fast and low-perturbation N2 removal method was developed, namely the evacuating/refilling-low temperature purging method. Notably, all C and N gases exhibited large within-day variations during the peak emission period, which can be addressed by high-frequency measurement. Based on the developed method, up to 97.8 % of gaseous C and 95.6 % of gaseous N losses were quantified over a 43-day compost incubation, with N2 emission accounting (on average) for 5.8 % of the initial total N. This system for high frequency measurement of multiple gases (including N2) provides a novel tool for obtaining a deeper understanding of C and N turnover and more accurate estimation of reactive N and greenhouse gas emissions during composting.

Produced Water Deoxygenation via Nitrogen Purging Scheme– Parametric Study – Part 2

In this following up paper, we present our findings by examining a pilot scale gasification column and applying nitrogen purging for samples of produced water grafted with different polyacrylamide concentrations (100 – 500 ppm). Upon applying a semi-batch, counter-current scheme for a series of experiments on packed gas-lift column, zero ppm level of dissolved oxygen (DO) was reached within less than 1 minute of nitrogen purging from the start time applied for solutions with viscosity less than 10 mPa.s and using the inline measuring scheme. However, zero ppm DO level was not reachable when purging produced water (PW) samples grafted with fresh polyacrylamide with a viscosity higher than 10 mPa.s. Nonetheless, the residues of DO were detected by offline measuring after examining the higher viscosity samples in the shallow limit (less than 0.4 ppm DO) and reached zero ppm when applying the inline measuring scheme. Two operation mode schemes, circulation, and once-through, were applied. Upon investigating the once-through contact scheme, the adopted nitrogen purging method was effective in reaching zero ppm level in less than 2 minutes, which is an excellent result compared with other well-known treatment techniques.

An Easy and Reliable Method for the Mitigation of Deuterated Chloroform Decomposition to Stabilise Susceptible NMR Samples

Highly reactive decomposition products of deuterated chloroform can deteriorate samples dissolved in this commonly used solvent for nuclear magnetic resonance (NMR) spectroscopy. Samples for metabolomics studies often contain a complex mixture of sensitive substances such as phospholipids, peptides, unsaturated fatty acids or vitamins. If these react with decomposition products (of chloroform), abnormal NMR spectra could result, e.g., signal shifts depending on pH, attenuation of signals over time due to chemical changes of analytes or new signals from reaction products. Such irreproducibly influenced spectra are especially problematic for non-targeted analysis methods using automated chemometrical data evaluation. To prevent these artefacts, chlorine, phosgene and hydrochloric acid need to be eliminated from deuterated chloroform before its use. Since the common stabilisation methods have proven to be insufficient for sensitive NMR samples, another purging method has been tested: Mitigation is easily and reliably achieved by washing the deuterated chloroform with concentrated disodium carbonate solution and subsequent desiccation with oven-dried disodium carbonate.

Novel Micro flow Sensor for Air Purge Method to Monitor the State of Charge of Lead Acid Battery

The foremost aim of the present research study is to measure specific gravity of lead-acid batteries and further know batterys state-of-charge (SoC). In this article, air purge method is used to monitor the status of a battery; back differential pressure is measured using MPX4006 DP MEMS pressure sensor. In air purge method, it is essential to adjust the rate of bubbles in acid. This can be achieved by controlling the compressors speed or controlling the air flow by controllers. When air purge tubes are inserted through a batterys cap, it is difficult to observe bubbles produced in the acid as the battery is nontransparent. If the bubble rate is too slow, the system lowers the output signal and hence stops working. During the calibration of the instrument, air flow measurement through the pipe is of prime importance. In this method, FS1012 MEMS gas flow sensor is used to monitor the discharged air flow. FS1012 is based on the thermo-transfer principle. Compared to the resistive technique, this flow sensor consists of a thermopile for air flow sensing whose signal-noise ratio is exceptional. The output of the sensor is exponential; signal conditioning circuit has been designed to get linear output 0 to 3.3 V standard range. The amplified output of signal conditioning circuit is monitored using TM4C123GXL arm controller. FS1020 is first time proposed to monitor the air flow of a small air purge probe used to monitor the state of charge of a lead-acid battery. FS1020 ensures an ideal flow of the air bubbler system, which improves the performance of the battery charge monitoring system. Conventional flow sensors for example, rotameter cannot be used for very low flow measurement; they are costlier as well as bulky. The minimum flow required to produce sufficient bubbles in acid is 0.50 liter per minute (LPM) which is measured by FS 1012.

Influence of pore volume and surface area on benzene adsorption capacity of activated carbons in indoor environments

Activated carbon is one of the most commonly used porous materials for capturing gaseous pollutants from indoor air. To investigate the adsorption behavior of activated carbon in an indoor environment, the benzene adsorption capacities of 11 commercial activated carbons were measured in the concentration range of 0.05–6 ppmv (parts per million by volume). The method of purging using clean air was used to measure the amount of benzene desorbed from the saturated activated carbons when the concentration decreased to zero. During the experiment, the temperature was 24 ± 2 °C and relative humidity was 45 ± 5%. The specific pore volumes and specific surface areas of the activated carbons were characterized, and their influence on the adsorption and reversible adsorption capacities was analyzed. The results showed that the benzene adsorption capacity has the strongest correlation with the pore volume in the pore width range of 0.6–0.9 nm, while the reversible adsorption capacity has the strongest correlation with the surface area for pore widths larger than 1 nm. Considering the strong correlation between the pore characteristics of the activated carbons and their adsorption behavior for benzene, it may be feasible to predict the adsorption equilibrium of activated carbons at low concentrations using the pore characteristics and empirical correlations.

Effect on high frequency resistance behavior of proton exchange membrane fuel cell during storage process

The high frequency resistance (HFR) is used to characterize the water content in the proton exchange membrane fuel cell (PEMFC), and the change of cell HFR during the storage process after gas purge with different storage and purge conditions is studied in this paper. The repeatability of the experiment is verified firstly. Then, the changes of cell HFR with different storage conditions include cell temperature, environment temperature, initial cell HFR are analyzed. Finally, the effect of purge conditions in the preparation stage on the cell HFR is studied by change the purge flow rate, purge gas type, purge methods. The results show that the cell HFR is affected by both the storage conditions and the purge operation conditions. The time for the PEMFC to reach the maximum HFR increases with the decrease of the environment temperature and the increase of the initial cell temperature. The final stable HFR value decreases with the increases of the environment temperature.

Using Freshwater Heads to Analyze Flow Directions in Saline Aquifers of the Pingtung Plain, Taiwan

The hydraulic head is the most important parameter for the study of groundwater. However, a head measured from observation wells containing groundwater of variable density should be corrected to a reference density (e.g., a freshwater head). Some previous case studies have used unknown density hydraulic heads for calibrating flow models. Errors arising from the use of observed hydraulic head data of unknown density are, therefore, likely one of the most overlooked issues in flow simulations of seawater intrusion. Here, we present a case study that uses the freshwater head, instead of the observed hydraulic head, to analyze the flow paths of saline groundwater in the coastal region of the Pingtung Plain, Taiwan. Out of a total of 134 observation wells within the Pingtung Plain, 19 wells have been determined to be saline, with Electric Conductivity (EC) values higher than 1500 μS/cm during 2012. The misuse of observed hydraulic heads causes misinterpretation of the flow direction of saline groundwater. For such saline aquifers, the determination of a freshwater head requires density information obtained from an observation well. Instead of the purging and sampling method, we recommend EC logging using a month interval. Our research indicates that EC values within an observation well within saline aquifers vary not only vertically but also by season.

Disordered eating symptoms in Austrian men of different ages in the context of fitness centers

PurposeTo assess eating behavior and associated factors in male fitness-center attendees.MethodsAn anonymous questionnaire was administered to male fitness center members of Innsbruck (Austria), aged 18–80 years to assess socio-demographic features, weight history, sports activity, eating behavior including disordered eating based on the Eating Disorder Examination Questionnaire (EDE-Q) and DSM-5 key symptoms for eating disorders (anorexia nervosa, binge eating, bulimia nervosa, purging disorder) and body image. Three age groups (younger—middle-aged—older men) were compared regarding the variables described above.ResultsA total of 307 men included displayed high rates of disordered eating as described by EDE-Q cutoff scores (5–11%) as well as by DSM-5 eating disorder symptoms (10%). While EDE-Q cutoff scores did not differentiate between the groups, the prevalences of DSM-5 eating disorder symptoms yielded significant differences indicating a clear decrease with increasing age. Binge eating and bulimic symptoms with excessive exercising as the purging method were the most often reported symptoms.ConclusionAlthough described as typically female, disordered eating does occur in male fitness-gym attendees across all ages. The older the men, the less prevalent are the symptoms. Awareness of disordered eating and possible negative effects need to be addressed for attendees and trainers of the gym.Level of evidenceV—descriptive survey study.

Flow analysis of a front opening unified pod (FOUP) subjected to different fan filter unit (FFU) coverage area in mini-environment

Moisture contamination control has been adopted in many wafer handling and storage processes. In portable wafer carriers called front opening unified pods (FOUPs), the current industry-accepted methods of moisture control are gas purging and laminar air curtain (LAC). Both typically use purified clean dry air (CDA). In this study, we investigated five different methods of FOUP moisture control: conventional and diffuser-based purging, LAC, and combinations of each purging method with LAC. Two different scenarios of 100% and 75% FFU coverage area were examined. The FOUP was empty and its internal volume was exposed to a mock-up mini-environment (ME)–a process confinement device used in semiconductor fabs. Also, the LAC was mounted inside the ME above the FOUP opening. Smoke flow visualization, particle image velocimetry (PIV) and humidity measurement were performed in the FOUP median plane. Streamline flow patterns were obtained from the PIV results that can significantly enhance the evaluation of the moisture removal performance of different case studies. The findings showed that the combination of diffuser purge and LAC was the most resistant against external lateral moist air flow wherein it yielded the lowest average humidity. The findings could be beneficial for reducing waste and increasing product quality in semiconductor manufacturing. This can lead to significant reductions in energy usage and drastically reduce manufacturing costs.

Analysis of Cyanide Compounds in Foods by the Purge Method Using a Midget Impinger

Cyanogenic glycosides in loquat (Eriobotrya japonica) seeds, which are used in so-called health foods, pose a public concern in Japan due to their potential health risks. Several pretreatment methods, such as the steam distillation and Conway microdiffusion methods, have been established for the determination of cyanogenic glycoside concentrations in foods. However, these methods are time-consuming and have extremely low throughput. Therefore, we developed a simple and rapid method, called the purge method, to analyze cyanide compounds in seed-derived food products. Under this method, the aqueous extract of cyanogenic glycosides is treated with β-glucosidase in a midget impinger, after which the liberated cyanide is purged into an absorbing solution. The concentration of cyanide in the adsorbent is then quantified using 4-pyridinecarboxylic acid-pyrazolone reagent. A single-laboratory method validation study was performed using amygdalin at a concentration of 10 ppm as cyanide ion. The validation parameter results (trueness, 83.9%; repeatability, 1.18%; intermediate precision, 4.67%) indicated that the developed method was suitable, precise and accurate. The purge method was used to analyze cyanide concentrations in commercially available food samples. Of the 10 samples tested (loquat seed powder, apricot kernel powder, and plum seed powder), three samples were found to contain cyanogenic glycosides at concentrations of >10 ppm as hydrogen cyanide, with the highest concentration detected being 861 ppm. These results clearly demonstrated the applicability of our method in determining cyanogenic glycosides in seed-derived food samples.

Performance Improvement of Condensation Reduction and Removal in Heat Recovery Ventilators Using Purge Methods

In this study, several purge and ventilation methods are proposed to reduce and remove condensation in a heat recovery ventilator for commercial and household buildings. The effects of the airflow rate, duration of ventilation, purge interval, and return air temperature on the quantities of condensation and condensation removal in the heat recovery ventilator are analyzed. The increase in the air flow rate and return air temperature increases the condensation removal rate owing to the enhanced evaporation of the condensate. Furthermore, the reductions in the duration of ventilation and purge interval decreased the accumulation of condensate on the heat exchanger element. Based on the experimental results, optimum ventilation and purge strategies are proposed according to the outdoor temperature. The operation of the heat recovery ventilator with the proposed ventilation and purge strategies shows at least a 33% and up to an 80% reduction in the quantity of condensate compared with a given operation method. Accordingly, the proposed operation strategies can significantly reduce the growth of microorganisms and fungi and also increase the efficiency of a heat recovery ventilator. However, further investigation on the detailed performance according to the outdoor humidity and overall energy analysis is necessary to supplement the limitations of this study.

Automotive Cold Start of a PEMFC System by Using a Methanol Solution as Antifreeze

Proton exchange membrane fuel cell vehicles are highly competitive due to their zero emissions, high efficiency and power density, quick response, low refuelling time and great autonomy. However, the lack of a sufficient hydrogen infrastructure and their required startup ability and durability at extreme winter conditions are limiting factors in their commercialisation. At subzero temperatures, the produced water during operation as well as the remained water in the cells after shutdown will freeze, hindering the cold start and causing several damages (e.g. cracks, pinholes, catalyst delamination or loss of electrochemical surface area). Commonly, the fuel cell system is purged with dried gases during shutdown to avoid that it freezes during the cold storage. Even though the dry gas purge methods have been extensively studied, thus reducing the degradation due to F/T cycles, there are still remaining unsolved issues, especially at very low temperatures. An alternative method that can mitigate this degradation and hence lower the temperature is the use of an antifreeze solution during the cold storage. Yet, it has been only tested in a single cell1. These results were quite promising, as the use of the antifreeze strongly diminished the degradation because of subzero temperatures and it was possible starting at -10°C. But they showed fairly poor cold start ability, since the residual methanol decreased the power density during the cold start. Therefore, the use of an antifreeze solution for a cold start should be further investigated in a stack.The aim of this study is to prove the cold start capability of a PEMFC system by using a methanol solution as antifreeze. For that, several cold starts at -10°C were carried out with a 4 kW commercial stack, a 25 vol% methanol solution to ensure no ice formation at -10°C and following next test protocol. A conditioning test and a polarization curve were conducted at room temperature. Then, the shutdown procedure, which involved soaking the stack with the methanol solution, was carried out before cooling down the system to -10°C. Following the cold storage, the antifreeze was removed from the stack and the cold start test was run. Finally, another polarization curve at room temperature was carried out. The cold start system ability with the antifreeze was compared with previous cold starts, which only used a dry gas purge method.All cold starts with antifreeze were successfully, thus proving the cold start capability of the PEMFC system by using the methanol solution. Indeed, they did not take longer than with the dry gas purge method. During the cold start the current generation did not decrease, which shows that the produced water did not freeze. Moreover, polarisation curves corroborated no performance losses after every cold start. These results are in concordance with those obtained at single cell level, as in both cases the antifreeze avoided ice formation during the cold storage. This significantly improvement with regard to the above results obtained with a single cell, is due to the ability of the stack to generate much more heat power and to minimize thermal losses, warming up the stack faster than a single cell.The obtained results allow confirming that a self-start of an automotive PEMFC system at subzero temperatures by using antifreeze solution is possible. This alternative method avoids ice formation during the cold storage, which reduces the degradation due to freezing and enables starting at lower temperatures. The decline in degradation increases the stack lifetime, thus can be achieved the strict automotive sector demands. The advantages of the antifreeze for automotive cold start can be used for others mobile applications too, such as trucks, trains, maritime or aircraft. In the future, cold starts with the antifreeze should be further investigated, and at temperatures down to -40°C.1. F. Knorr, D. Garcia, J. Schirmer, P. Gazdizcki, and KA. Friedrich. Appl. Energy, 238, 1 (2019).