Effects of heterogeneous reaction with NO2 on ice nucleation activities of feldspar and Arizona Test Dust.

Mineral dust is an important type of ice nucleating particles in the troposphere; however, the effects of heterogeneous reactions on ice nucleation (IN) activities of mineral dust remain to be elucidated. A droplet-freezing apparatus (Guangzhou Institute of Geochemistry Ice Nucleation Apparatus, GIGINA) was developed in this work to measure IN activities of atmospheric particles in the immersion freezing mode, and its performance was validated by a series of experimental characterizations. This apparatus was then employed to measure IN activities of feldspar and Arizona Test Dust (ATD) particles before and after heterogeneous reaction with NO2 (10±0.5 ppmv) at 40% relative humidity. The surface coverage of nitrate, θ(NO3-), increased to 3.1±0.2 for feldspar after reaction with NO2 for 6 hr, and meanwhile the active site density per unit surface area (ns) at -20°C was reduced from 92±5 to <1.0 cm-2 by about two orders of magnitude; however, no changes in nitrate content or IN activities were observed for further increase in reaction time (up to 24 hr). Both nitrate content and IN activities changed continuously with reaction time (up to 24 hr) for ATD particles; after reaction with NO2 for 24 hr, θ(NO3-) increased to 1.4±0.1 and ns at -20°C was reduced from 20±4 to 9.7±1.9 cm-2 by a factor of ∼2. Our work suggests that heterogeneous reaction with NO2, an abundant reactive nitrogen species in the troposphere, may significantly reduce IN activities of mineral dust in the immersion freezing mode.

Heterogeneous reaction of NO2 with feldspar, three clay minerals and Arizona Test Dust.

Heterogeneous reaction of NO2 with mineral dust aerosol may play important roles in troposphere chemistry, and has been investigated by a number of laboratory studies. However, the influence of mineralogy on this reaction has not been well understood, and its impact on aerosol hygroscopicity is not yet clear. This work investigated heterogeneous reactions of NO2 (∼10 ppmv) with K-feldspar, illite, kaolinite, montmorillonite and Arizona Test Dust (ATD) at room temperature as a function of relative humidity (<1% to 80%) and reaction time (up to 24 hr). Heterogeneous reactivity towards NO2 was low for illite, kaolinite, montmorillonite and ATD, and uptake coefficients of NO2, γ(NO2), were determined to be around or smaller than 1×10-8; K-feldspar exhibited higher reactivity towards NO2, and CaCO3 is most reactive among the nine mineral dust samples considered in this and previous work. After heterogeneous reaction with NO2 for 24 hr, increase in hygroscopicity was nearly insignificant for illite, kaolinite and montmorillonite, and small but significant for K-feldspar; in addition, large increase in hygroscopicity was observed for ATD, although the increase in hygroscopicity was still smaller than CaCO3.

Heterostructures with Built-in Electric Fields for Long-lasting Chemodynamic Therapy.

Sustained signal activation by hydroxyl radicals (⋅OH) has great significance, especially for tumor treatment, but remains challenging. Here, a built-in electric field (BIEF)-driven strategy was proposed for sustainable generation of ⋅OH, thereby achieving long-lasting chemodynamic therapy (LCDT). As a proof of concept, a novel Janus-like Fe@Fe3 O4 -Cu2 O heterogeneous catalyst was designed and synthesized, in which the BIEF induced the transfer of electrons in the Fe core to the surface, reducing ≡Cu2+ to ≡Cu+ , thus achieving continuous Fenton-like reactions and ⋅OH release for over 18 h, which is approximately 12 times longer than that of Fe3 O4 -Cu2 O and 72 times longer than that of Cu2 O nanoparticles. In vitro and in vivo antitumor results indicated that sustained ⋅OH levels led to persistent extracellular regulated protein kinases (ERK) signal activation and irreparable oxidative damage to tumor cells, which promoted irreversible tumor apoptosis. Importantly, this strategy provides ideas for developing long-acting nanoplatforms for various applications.

Hygroscopic properties of sodium and potassium salts as related to saline mineral dusts and sea salt aerosols.

Mineral dust, soil, and sea salt aerosols are among the most abundant primary inorganic aerosols in the atmosphere, and their hygroscopicity affects the hydrological cycle and global climate. We investigated the hygroscopic behaviors of six Na- and K-containing salts commonly found in those primary organic aerosols. Their hygroscopic growths as a function of relative humidity (RH) agree well with thermodynamic model prediction. Temperature dependence of deliquescence RH (DRH) values for five of those salts was also investigated, which are comparable to those in literature within 1%-2% RH, most showing negative dependence on temperature. Hygroscopic growth curves of real-world soil and sea salt samples were also measured. The hygroscopic growths of two more-hydroscopic saline soil samples and of sea salt can be predicted by the thermodynamic model based on the measured water-soluble ionic composition. The substantial amounts of water-soluble ions, including Na+ and K+, in saline soil samples imply that even nascent saline soil samples are quite hygroscopic at high-RH (>80%) conditions. For three less-hygroscopic dust samples, however, measurements showed higher water uptake ability than that predicted by the thermodynamic model. The small amount of water taken up by less-hygroscopic dust samples suggests that dust particles might contain thin layers of water even to very low RH. The results of this study provide a comprehensive characterization of the hygroscopicity of Na- and K-containing salts as related to their roles in the hygroscopic behaviors of saline mineral dusts and sea salt aerosols.

Evolution of Digital Health and Exploration of Patented Technologies (2017-2021): Bibliometric Analysis.

BACKGROUND: The significant impact of digital health emerged prominently during the COVID-19 pandemic. Despite this, there is a paucity of bibliometric analyses focusing on technologies within the field of digital health patents. Patents offer a wealth of insights into technologies, commercial prospects, and competitive landscapes, often undisclosed in other publications. Given the rapid evolution of the digital health industry, safeguarding algorithms, software, and advanced surgical devices through patent systems is imperative. The patent system simultaneously acts as a valuable repository of technological knowledge, accessible to researchers. This accessibility facilitates the enhancement of existing technologies and the advancement of medical equipment, ultimately contributing to public health improvement and meeting public demands. OBJECTIVE: The primary objective of this study is to gain a more profound understanding of technology hotspots and development trends within the field of digital health. METHODS: Using a bibliometric analysis methodology, we assessed the global technological output reflected in patents on digital health published between 2017 and 2021. Using Citespace5.1R8 and Excel 2016, we conducted bibliometric visualization and comparative analyses of key metrics, including national contributions, institutional affiliations, inventor profiles, and technology topics. RESULTS: A total of 15,763 digital health patents were identified as published between 2017 and 2021. The China National Intellectual Property Administration secured the top position with 7253 published patents, whereas Koninklijke Philips emerged as the leading institution with 329 patents. Notably, Assaf Govari emerged as the most prolific inventor. Technology hot spots encompassed categories such as "Medical Equipment and Information Systems," "Image Analysis," and "Electrical Diagnosis," classified by Derwent Manual Code. A patent related to the technique of receiving and transmitting data through microchips garnered the highest citation, attributed to the patentee Covidien LP. CONCLUSIONS: The trajectory of digital health patents has been growing since 2017, primarily propelled by China, the United States, and Japan. Applications in health interventions and enhancements in surgical devices represent the predominant scenarios for digital health technology. Algorithms emerged as the pivotal technologies protected by patents, whereas techniques related to data transfer, storage, and exchange in the digital health domain are anticipated to be focal points in forthcoming basic research.

Induction of pancreatic cancer cell apoptosis, invasion, migration, and enhancement of chemotherapy sensitivity of gemcitabine, 5-FU, and oxaliplatin by hnRNP A2/B1 siRNA.

We investigated the effects of inhibiting heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) expression on apoptosis, invasion, migration, and the chemotherapy sensitivity of pancreatic cancer cells to gemcitabine, 5-FU, and oxaliplatin chemotherapy using small interfering RNA (siRNA). Chemically synthesized siRNA hnRNP A2/B1 was transfected into the human pancreatic cancer cell lines SW1990 and BxPC-3. The IC(50) of gemcitabine, 5-FU, and oxaliplatin was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Cell apoptosis and cycle were detected using flow cytometry. The expressions of apoptosis-related genes, p53, Bax, Bcl-2, TRAIL, Survivin, multidrug resistance 1 (MDR1), E-cadherin, and matrix metalloproteinases-2 (MMP-2) were detected using real-time PCR and western blot. Plate colony formation assay, wound scratch assay, invasion, and migration were also examined. Gemcitabine, 5-FU, and oxaliplatin inhibit the proliferation of SW1990 and BxPC-3 cells in a concentration-dependent manner. Inhibition of hnRNP A2/B1 expression significantly reduced the IC(50) of gemcitabine, 5-FU, and oxaliplatin (P<0.01). hnRNP A2/B1 siRNA combined with gemcitabine, 5-FU and oxaliplatin significantly increased (P<0.01) apoptosis of pancreatic cancer cell lines SW1990 and BxPC-3, increased the expression level of Bax mRNA, decreased Bcl-2 mRNA and MDR1 mRNA expression (P<0.01), and induced no change in p53, TRAIL, and Survivin mRNA expression in SW1990. In the western blot analysis, the expression level of Bax protein increased (P<0.01); the expression of both P-glycoprotein (Pg-p) protein and Bcl-2 protein decreased (P<0.01). Silencing hnRNP A2/B1 decreased invasion and migration in the cell line SW1990. Silencing hnRNP A2/B1 in SW1990 also correlated with an increase in E-cadherin expression and a decrease in MMP-2 expression at the same time. Inhibition of hnRNP A2/B1 expression can induce apoptosis in pancreatic cancer cells and improve chemosensitivity to gemcitabine, 5-FU, and oxaliplatin. hnRNP A2/B1 may play a role in invasion and migration in the pancreatic cancer cell line SW1990 through the regulation of E-cadherin and expression of MMP-2.

Emergence of heterogeneous nuclear ribonucleoprotein A2/B1 vs loss of E-cadherin: their reciprocal immunoexpression profiles in human pancreatic cancer.

Pancreatic cancer is one of the most lethal human cancers worldwide. It is important to develop new screening methods or biomarkers related to pancreatic carcinogenesis. In our previous work, we identified heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1 as one of the up-regulated proteins in rat pancreatic cancer by using proteomic analysis. In the current study, we extended our research to investigate the immunoexpression of hnRNP A2/B1 protein in paired tumor/nontumor tissues from 42 patients with primary pancreatic ductal adenocarcinoma and its correlation to E-cadherin expression and clinicopathologic features. The results showed that the frequency of hnRNP A2/B1 expression is 71.4% (30/42), and loss of E-cadherin is 61.9% (26/42) in pancreatic cancer tissue. Emergence of hnRNP A2/B1 (P = .027) and loss of E-cadherin (P = .012) expression were significantly associated with poor differentiation of pancreatic cancer. In addition, E-cadherin loss expression was associated with lymph node metastasis (P = .042). Most importantly, there was an inverse correlation between the emergence of hnRNP A2/B1 and loss of E-cadherin expression in pancreatic cancer (P = .01). Collectively, we demonstrate altered expression profile of hnRNP A2/B1 protein in human pancreatic cancer and its reciprocal correlation to E-cadherin expression. These data indicate that hnRNP A2/B1 overexpression is novel and requires further investigation for its potential application in pancreatic carcinogenesis.

Evaluation of Chinese healthcare organizations' innovative performance in the digital health era.

Background: Healthcare workers' relationship with industry is not merely an agent mediating between consumer and vendor, but they are also inventors of the interventions they exist to deliver. Driven by the background of the digital health era, scientific research and technological (Sci-tech) innovation in the medical field are becoming more and more closely integrated. However, scholars shed little light on Sci-tech relevance to evaluate the innovation performance of healthcare organizations, a distinctive feature of healthcare organizations' innovation in the digital health era. Methods: Academic publications and patents are the manifestations of scientific research outputs and technological innovation outcomes, respectively. The study extracted data from publications and patents of 159 hospitals in China to evaluate their innovation performance. A total of 18 indicators were constructed, four of which were based on text similarity match and represented the Sci-tech relevance. We then applied factor analyses, analytical hierarchy process, and logistic regression to construct an evaluation model. We also examined the relationship between hospitals' innovation performance and their geographical locations. Finally, we implemented a mediation analysis to show the influence of digital health on hospital innovation performance. Results: A total of 16 indicators were involved, four of which represented the Sci-tech including the number of articles matched per patent (NAMP), the number of patents matched per article (NPMA), the proportion of highly matched patents (HMP), and the proportion of highly matched articles (HMA). Indicators of HMP (r = 0.52, P = 2.40 × 10-12), NAMP (r = 0.52, P = 2.54 × 10-12), and NPMA (r = 0.51, P = 5.53 × 10-12) showed a strong positive correlation with hospital innovation performance score. The evaluation model in this study was different from other Chinese existing hospital ranking systems. The regional innovation performance index (RIP) of healthcare organizations is highly correlated with per capita disposable income (r = 0.58) and regional GDP (r = 0.60). There was a positive correlation between digital health innovation performance scores and overall hospital innovation performance scores (r = 0.20). In addition, the hospitals' digital health innovation performance affected the hospital's overall innovation score with the mediation of Sci-tech relevance indicators (NPMA and HMA). The hospitals' digital health innovation performance score showed a significant correlation with the number of healthcare workers (r = 0.44). Conclusion: This study constructed an assessment model with four invented indicators focusing on Sci-tech relevance to provide a novel tool for researchers to evaluate the innovation performance of healthcare organizations in the digital health era. The regions with high RIP were concentrated on the eastern coastal areas with a higher level of economic development. Therefore, the promotion of scientific and technological innovation policies could be carried out in advance in areas with better economic development. The innovations in the digital health field by healthcare workers enhance the Sci-tech relevance in hospitals and boost their innovation performance. The development of digital health in hospitals depends on the input of medical personnel.

Gestational palmitic acid suppresses embryonic GATA-binding protein 4 signaling and causes congenital heart disease.

Dysregulated maternal fatty acid metabolism increases the risk of congenital heart disease (CHD) in offspring with an unknown mechanism, and the effect of folic acid fortification in preventing CHD is controversial. Using gas chromatography coupled to either a flame ionization detector or mass spectrometer (GC-FID/MS) analysis, we find that the palmitic acid (PA) concentration increases significantly in serum samples of pregnant women bearing children with CHD. Feeding pregnant mice with PA increased CHD risk in offspring and cannot be rescued by folic acid supplementation. We further find that PA promotes methionyl-tRNA synthetase (MARS) expression and protein lysine homocysteinylation (K-Hcy) of GATA4 and results in GATA4 inhibition and abnormal heart development. Targeting K-Hcy modification by either genetic ablation of Mars or using N-acetyl-L-cysteine (NAC) decreases CHD onset in high-PA-diet-fed mice. In summary, our work links maternal malnutrition and MARS/K-Hcy with the onset of CHD and provides a potential strategy in preventing CHD by targeting K-Hcy other than folic acid supplementation.

Induction of pancreatic cancer cell apoptosis and enhancement of gemcitabine sensitivity by RAP80 siRNA.

BACKGROUND: Receptor-associated protein 80 (RAP80) increases substantially in pancreatic cancer. The involvement of RAP80 in the chemoresistance of pancreatic cancer should be elucidated. AIMS: We investigated the effects of inhibiting RAP80 expression on the sensitivity of pancreatic cancer cells to gemcitabine chemotherapy by using small interfering RNA (siRNA). METHODS: Chemically synthesized siRNA RAP80 was transfected into human pancreatic cancer cell lines SW1990 and Capan-2. The IC(50) of gemcitabine was determined by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Cell apoptosis was detected by using flow cytometry. Expression of apoptosis-related genes, Bax, Bcl-2, TRAIL, survivin, and caspase-8 was detected by using reverse transcription-polymerase chain reaction (RT-PCR) and western blot. RESULTS: Gemcitabine inhibits proliferation of SW1990 and Capan-2 cells in a concentration-dependent manner. Inhibition of RAP80 expression significantly reduced the IC(50) of gemcitabine (P < 0.01). RAP80 siRNA combined with gemcitabine significantly increased (P < 0.01) apoptosis of pancreatic cancer cell lines SW1990 and Capan-2, increased expression of Bax mRNA, reduced Bcl-2 mRNA expression (P < 0.01), and slightly increased TRAIL mRNA expression (P < 0.01). Correspondingly, in the RAP80 siRNA combined with gemcitabine group, both Bax and cleaved caspase-8 protein levels were increased (P < 0.01), whereas Bcl-2 protein decreased significantly (P < 0.01). No change in survivin mRNA expression was observed (P < 0.01). CONCLUSION: Inhibition of RAP80 expression can induce apoptosis in pancreatic cancer cells and improve chemosensitivity to gemcitabine.

Efficacy and Mechanism of Trimebutine Maleate Combined with Lactulose in the Treatment of Constipation-Predominant Irritable Bowel Syndrome in the Elderly.

Objective: Study on the efficacy and mechanism of trimebutine maleate combined with lactulose in the treatment of constipation-predominant irritable bowel syndrome (IBS-C) in the elderly. Methods: From March 2019 to March 2021, 102 elderly patients with IBS-C were randomly divided into the observation group (51 cases) and the control group (51 cases). The observation group was treated with trimebutine maleate combined with lactulose, while the control group was treated with lactulose. Comparison of the clinical effects of the two groups. Comparison of vasoactive intestinal peptide (VIP) levels, neuropeptide Y (NPY) levels, and quality of life scores before and after treatment between the two groups. Documentation of adverse reactions during treatment. Results: The improvement of clinical symptoms in the observation group was significantly better than that in the control group, and the difference is statistically significant (P < 0.05). The level of VIP after treatment in the observation group was significantly lower than that in the control group and before treatment, and the differences were statistically significant (P < 0.05). The level of NPY after treatment in the observation group was significantly higher than that in the control group and before treatment, and the differences were statistically significant (P < 0.05). The scores of dietary restrictions and health worries in the control group after treatment were significantly higher than those before treatment, and the differences were statistically significant (P < 0.05). The scores of anxious, behavioral conflict, dietary restrictions, health worries, social response, and family relationship in the observation group after treatment were significantly higher than those in the control group and before treatment, and the differences were statistically significant (P < 0.05). There were no serious adverse effects in either group during the treatment period, with some patients experiencing dizziness and dry mouth, which improved after discontinuation of the drug, without special intervention. Conclusion: Trimebutine maleate combined with lactulose can improve clinical symptoms and quality of life in elderly patients with IBS-C, and its mechanism of action may be related to the regulation of the body's VIP and NPY levels.

Scientific research competitiveness in hospitals: A narrative review of major hospital ranking systems in China.

Background and Aims: Several hospital ranking systems have been created in China recently, but there is still a lack of comprehensive analysis of the weight and significance of scientific research in hospital ranking. The present study aimed to identify and analyze the role of scientific research competitiveness in various hospital ranking systems in China. Methods: Over 200 materials published between 2010 and 2020 and related to three mainstream hospital ranking systems in China were reviewed. The methodologies applied in the three ranking systems were analyzed and compared. In addition, the comparative learning and analysis of Top 10 and Top 46-55 hospitals according to the ranking system of China's Best Hospital Rankings was performed for a longitudinal study. Results: The three major hospital rankings had different scientific research capability ranking methodologies and emphases of scientific research evaluation systems. The most commonly used indicators were science citation index (SCI) publications, National Scientific Foundation of China funding, a number of national key laboratories, and a number of academicians. The relative standing of several top hospitals showed slightly different in the three major Chinese hospital ranking systems. For the longitudinal study, we found that the fluctuation of the ranking of the Top 46-55 hospitals was significantly higher than that of the Top 10 hospitals, in which scientific research played a vital role. Conclusion: The proportion of scientific research plays an important role in the hospital ranking systems. The quality and quantity of SCI publications, the key indicators of national projects, and top academic talents are the most important factors used to evaluate the level of hospital scientific research, and thus affect the ranking of hospitals.

Serum MMP-9 and SAA in the Diagnosis of Severe Pneumonia Caused by Radiotherapy of Esophageal Cancer.

OBJECTIVE: To explore the relationship and diagnostic value of serum MMP-9 and SAA in severe pneumonia (sCAP) caused by radiotherapy of esophageal cancer. METHODS: A total of 144 esophageal cancer patients who underwent radiotherapy in our hospital from April 2016 to February 2018 were collected. Among them, 58 patients without radiation pneumonitis (RP) were in the control group, 49 patients with grade 1∼2 RP were in the radiation group, and 37 patients with sCAP were in the severe group. The levels of serum MMP-9 and SAA in every group of patients were detected. The ROC curve was used to determine the diagnostic value of serum MMP-9 and SAA in the diagnosis of RP and sCAP. The correlation between serum MMP-9 and SAA and the patient's lung function indexes was analyzed, and the logistic single-factor and multivariate analyses were performed to analyze the factors of sCAP in esophageal cancer radiotherapy. RESULTS: PaO2, FVC, and FEV1 decreased in RP and sCAP, and PaCO2, white blood cells, serum MMP-9, and SAA levels increased (P < 0.05); serum MMP-9 and SAA were negatively correlated with lung function (P < 0.05); the AUC of serum MMP-9 and SAA in RP was 0.833 and 0.823, respectively, and the AUC of the two combined diagnosis of RP was 0.919. The AUC of serum MMP-9 and SAA in sCAP was 0.809 and 0.797, respectively, and the AUC of both combined diagnosis of sCAP was 0.873; logistics multivariate analysis found that serum MMP-9, serum SAA, double lung V5, and V20 were independent risk factors for sCAP caused by radiotherapy for esophageal cancer (P < 0.05). CONCLUSION: Serum MMP-9 and SAA increase in RP and sCAP and are negatively correlated with lung function in patients with pneumonia. They are independent risk factors for severe pneumonia caused by radiotherapy of esophageal cancer and have good diagnostic value.

Transmission of a Novel Imprinting Center Deletion Associated With Prader-Willi Syndrome Through Three Generations of a Chinese Family: Case Presentation, Differential Diagnosis, and a Lesson Worth Thinking About.

Prader-Willi syndrome (PWS) is a complex genetic syndrome caused by the loss of function of genes in 15q11-q13 that are subject to regulation by genomic imprinting and expressed from the paternal allele only. The main clinical features of PWS patients are hypotonia during the neonatal and infantile stages, accompanied by delayed neuropsychomotor development, hyperphagia, obesity, hypogonadism, short stature, small hands and feet, mental disabilities, and behavioral problems. However, PWS has a clinical overlap with other disorders, especially those with other gene variations or chromosomal imbalances but sharing part of the similar clinical manifestations with PWS, which are sometimes referred to as Prader-Willi syndrome-like (PWS-like) disorders. Furthermore, it is worth mentioning that significant obesity as a consequence of hyperphagia in PWS usually develops between the ages of 1 and 6 years, which makes early diagnosis difficult. Thus, PWS is often not clinically recognized in infants and, on the other hand, may be wrongly suspected in obese and intellectually disabled patients. Therefore, an accurate investigation is necessary to differentiate classical PWS from PWS-like phenotypes, which is imperative for further treatment. For PWS, it is usually sporadic, and very rare family history and affected siblings have been described. Here, we report the clinical and molecular findings in a three-generation family with a novel 550-kb microdeletion affecting the chromosome 15 imprinting center (IC). Overall, the present study finds that the symptoms of our patient are somewhat different from those of typical PWS cases diagnosed and given treatment in our hospital. The familial occurrence and clinical features were challenging to our diagnostic strategy. The microdeletion included a region within the complex small nuclear ribonucleoprotein polypeptide protein N (SNRPN) gene locus encompassing the PWS IC and was identified by using a variety of techniques. Haplotype studies suggest that the IC microdeletion was vertically transmitted from an unaffected paternal grandmother to an unaffected father and then caused PWS in two sibling grandchildren when the IC microdeletion was inherited paternally. Based on the results of our study, preimplantation genetic diagnosis (PGD) was applied successfully to exclude imprinting deficiency in preimplantation embryos before transfer into the mother's uterus. Our study may be especially instructive regarding accurate diagnosis, differential diagnosis, genetic counseling, and PGD for familial PWS patients.

Compilation and evaluation of gas phase diffusion coefficients of halogenated organic compounds.

Organic halogens are of great environmental and climatic concern. In this work, we have compiled their gas phase diffusivities (pressure-normalized diffusion coefficients) in a variety of bath gases experimentally measured by previous studies. It is found that diffusivities estimated using Fuller's semi-empirical method agree very well with measured values for organic halogens. In addition, we find that at a given temperature and pressure, different molecules exhibit very similar mean free paths in the same bath gas, and then propose a method to estimate mean free paths in different bath gases. For example, the pressure-normalized mean free paths are estimated to be 90, 350, 90, 80, 120 nm atm in air (and N2/O2), He, argon, CO2 and CH4, respectively, with estimated errors of around ±25%. A generic method, which requires less input parameter than Fuller's method, is proposed to calculate gas phase diffusivities. We find that gas phase diffusivities in He (and air as well) calculated using our method show fairly good agreement with those measured experimentally and estimated using Fuller's method. Our method is particularly useful for the estimation of gas phase diffusivities when the trace gas contains atoms whose diffusion volumes are not known.