A murine periodontitis model using coaggregation between human pathogens and a predominant mouse oral commensal bacterium

Liu, Mengmeng,Choi, Youngnim Korean Academy of Periodontology 2021 Journal of Periodontal & Implant Science Vol.51 No.-

Purpose: C57BL/6 mice, which are among the most common backgrounds for genetically engineered mice, are resistant to the induction of periodontitis by oral infection with periodontal pathogens. This study aimed to develop a periodontitis model in C57BL/6 mice using coaggregation between human pathogens and the mouse oral commensal Streptococcus danieliae (Sd). Methods: The abilities of Porphyromonas gingivalis ATCC 33277 (Pg33277), P. gingivalis ATCC 49417 (Pg49417), P. gingivalis KUMC-P4 (PgP4), Fusobacterium nucleatum subsp. nucleatum ATCC 25586 (Fnn), and F. nucleatum subsp. animalis KCOM 1280 (Fna) to coaggregate with Sd were tested by a sedimentation assay. The Sd-noncoaggregating Pg33277 and 2 Sd-coaggregating strains, PgP4 and Fna, were chosen for animal experiments. Eighty C57BL/6 mice received oral gavage with Sd once and subsequently received vehicle alone (sham), Fna, Pg33277, PgP4, or Fna+PgP4 6 times at 2-day intervals. Mice were evaluated at 5 or 8 weeks after the first gavage of human strains. Results: Fnn, Fna, and PgP4 efficiently coaggregated with Sd, but Pg33277 and Pg49417 did not. Alveolar bone loss was significantly higher in the PgP4 group at both time points (weeks 5 and 8) and in all experimental groups at week 8 compared with the sham group. The PgP4 group presented greater alveolar bone loss than the other experimental groups at both time points. A higher degree of alveolar bone loss accompanied higher bacterial loads in the oral cavity, the invasion of not only PgP4 but also Sd and Fna, and the serum antibody responses to these bacteria. Conclusions: Periodontitis was successfully induced in C57BL/6 mice by oral infection with a P. gingivalis strain that persists in the oral cavity through coaggregation with a mouse oral commensal bacterium. This new model will be useful for studying the role of human oral bacteria-host interactions in periodontitis using genetically engineered mice.

A murine periodontitis model using coaggregation between human pathogens and a predominant mouse oral commensal bacterium

Mengmeng Liu,최영님 대한치주과학회 2022 Journal of Periodontal & Implant Science Vol.52 No.2

Purpose: C57BL/6 mice, which are among the most common backgrounds for genetically engineered mice, are resistant to the induction of periodontitis by oral infection with periodontal pathogens. This study aimed to develop a periodontitis model in C57BL/6 mice using coaggregation between human pathogens and the mouse oral commensal Streptococcus danieliae (Sd). Methods: The abilities of Porphyromonas gingivalis ATCC 33277 (Pg33277), P. gingivalis ATCC 49417 (Pg49417), P. gingivalis KUMC-P4 (PgP4), Fusobacterium nucleatum subsp. nucleatum ATCC 25586 (Fnn), and F. nucleatum subsp. animalis KCOM 1280 (Fna) to coaggregate with Sd were tested by a sedimentation assay. The Sd-noncoaggregating Pg33277 and 2 Sd-coaggregating strains, PgP4 and Fna, were chosen for animal experiments. Eighty C57BL/6 mice received oral gavage with Sd once and subsequently received vehicle alone (sham), Fna, Pg33277, PgP4, or Fna+PgP4 6 times at 2-day intervals. Mice were evaluated at 5 or 8 weeks after the first gavage of human strains. Results: Fnn, Fna, and PgP4 efficiently coaggregated with Sd, but Pg33277 and Pg49417 did not. Alveolar bone loss was significantly higher in the PgP4 group at both time points (weeks 5 and 8) and in all experimental groups at week 8 compared with the sham group. The PgP4 group presented greater alveolar bone loss than the other experimental groups at both time points. A higher degree of alveolar bone loss accompanied higher bacterial loads in the oral cavity, the invasion of not only PgP4 but also Sd and Fna, and the serum antibody responses to these bacteria. Conclusions: Periodontitis was successfully induced in C57BL/6 mice by oral infection with a P. gingivalis strain that persists in the oral cavity through coaggregation with a mouse oral commensal bacterium. This new model will be useful for studying the role of human oral bacteria-host interactions in periodontitis using genetically engineered mice.

Ideological and Political Evaluation of English Courses in Heterogeneous Campuses Based on UAV Network

Mengmeng Liu 한국멀티미디어학회 2023 The journal of multimedia information system Vol.10 No.3

Campus heterogeneity has become prominent with the deeper popularization of higher education, necessitating more focused ideological and political instruction. English classes are crucial because they help students develop their humanistic traits and capacity for intercultural dia-logue. Although it is a realistic strategy, integrating ideological and political education into English instruction depends on scientific assessment of the educational quality. Existing assessment approaches, however, need to be more particular for English courses and flexible enough to accommodate diverse student populations. Traditional questionnaire surveys are only sometimes accurate, timely, or complete. Therefore, based on the unmanned aerial vehicle (UAV) network, this research suggests a novel ideological and political education quality evaluation approach for English courses at varied campuses. A consistency feature extraction method is used to identify the ideological and political fac-tors in English teaching by analyzing the consistency between English courses and ideological and political courses. The analytic hierarchy process determines the indicator weights. Teachers' education roles are quantified based on educational psychology theories. A UAV network is leveraged to collect real-time classroom data adaptively across various campus types—fuzzy comprehensive evaluation aggregates multi-source data for objective and pertinent assessment. Experiments on three campus types and 60 teachers validate the effectiveness. The model achieves over 84% accuracy, significantly higher than conventional questionnaire and fixed sensor methods. The results match expert opinions and offer diagnostic suggestions to improve teaching. The model provides a practical data-driven approach to evaluate and enhance the ideo-logical and political education quality through English courses on heterogeneous campuses.

The mediating role of atrial fibrillation in causal associations between risk factors and stroke: a Mendelian randomization study

Shanmei Qin(Shanmei Qin),Mengmeng Wang(Mengmeng Wang),Dipender Gill(Dipender Gill ),Zhizhong Zhang(Zhizhong Zhang),Xinfeng Liu(Xinfeng Liu) 한국역학회 2024 Epidemiology and Health Vol.46 No.-

Preparation and Investigation of Fe3O4@rGO/CNF Foams for Electromagnetic Interference Shielding

Mengmeng Li,Qiuyu Xu,Wei Jiang,Amjad Farooq,Yirui Qi,Lifang Liu 한국섬유공학회 2023 Fibers and polymers Vol.24 No.2

Herein, Fe3O4nanoparticles and graphene oxide (GO) are compounded first, followed by the addition of cellulose nanofiber(CNF) and l-ascorbic acid, to obtain Fe3O4@reduced graphene oxide (rGO)/CNF foams via the freeze-drying method. Theelectrical conductivity and magnetism of as-prepared foams were improved due to the presence of rGO and Fe3O4,whichis suitable for electromagnetic interference (EMI) shielding material. The results exhibit that Fe3O4@rGO/CNF foams allpossess a porous structure, and the optimized foam shows an EMI shielding effectiveness value of ~ 23 dB in the X-band. The good EMI shielding performance of the Fe3O4@rGO/CNF foam originates from the synergy of its composition andstructure. This work could provide a reference for the design and fabrication of novel EMI shielding materials.

Graphene oxide nanosheets to improve permeability and selectivity of PIM-1 membrane for carbon dioxide separation

Mengmeng Chen,Faizal Soyekwo,Qiugen Zhang,Chuan Hu,Aimei Zhu,Qinglin Liu 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.63 No.-

Polymers of intrinsic microporosity (PIMs) have attracted increasing interest in gas separation membranes due to their high permeability. However, the moderate selectivity limits their wide applications in CO2 separation. Herein we report a facile strategy to improve simultaneously the permeability and CO2 selectivity of PIMs membrane using the prepared PIM-1/graphene oxide (GO) nanosheets mixed matrix membrane. The GO nanosheets improves the hydrophilicity and surface roughness of PIM-1 membrane whereas the uniform assembly of GO nanosheets in the PIM-1 matrix creates the hydrophilic/hydrophobic microphase segregation in the membrane. The as-prepared mixed matrix membrane is also very porous and has a pore size of about 0.78 nm. The combination of these properties significantly contributes to the enhancement of the gas separation performance of PIM-1 membrane, with the resultant membrane exhibiting an exceptionally high CO2 permeability of up to 6169 barrer as well as a high CO2/N2 selectivity of 123.5, which is more than 7 times that of the pure PIM-1 membrane. The developed PIM-1/GO mixed matrix membrane should have a wide application in the CO2 separation.

Wideband Tri-band Filter Design using Stepped-impedance Stub Resonators

Mengmeng Cui,Yun Liu,Shengjun Xue,Jin Wang 보안공학연구지원센터 2013 International Journal of Hybrid Information Techno Vol.6 No.5

Sustained electron tunneling at unbiased metal-insulator-semiconductor triboelectric contacts

Liu, Jun,Miao, Mengmeng,Jiang, Keren,Khan, Faheem,Goswami, Ankur,McGee, Ryan,Li, Zhi,Nguyen, Lan,Hu, Zhiyu,Lee, Jungchul,Cadien, Ken,Thundat, Thomas Elsevier 2018 Nano energy Vol.48 No.-

<P><B>Abstract</B></P> <P>Generating sufficient current density for powering electronic devices remains as one of the critical challenges of mechanical energy harvesting techniques based on piezo and triboelectricity, mainly due to the high impedance of the insulating material systems. Here we report on producing sustainable tunneling current using an unbiased, triboelectrically charged metal-insulator-semiconductor (MIS) point contact system, consisting of p-type silicon, silicon oxide and a metal tip. The native thin oxide (~ 1.6 nm) on the silicon surface provides a natural pathway for quantum mechanical tunneling of the triboelectrically generated electrons into the silicon substrate. Lateral back and forth sliding motion of the tip, irrespective of the direction of motion, generates a constant direct current (d.c.) with very high current density. The measured current shows an exponential decay with the thickness of oxide layer deposited with atomic layer deposition (ALD), confirming the quantum mechanical tunneling mechanism. It is proposed that the contact potential difference enhanced by triboelectric charging provides potential difference between metal point contact and the substrate. With single metallic micro probe sliding on a moderately doped p-type silicon, an open circuit voltage (<I>V</I> <SUB>oc</SUB>) of 300–400 mV and a short-circuit direct current (<I>I</I> <SUB>sc</SUB>) of 3–5 μA (a corresponding high current density, <I>J</I>, in the order of 1–10 A/m<SUP>2</SUP>) have been observed. It is predicted from conductive-atomic force microscopy (C-AFM) experiment that the theoretical <I>J</I> can be as high as 10<SUP>4</SUP> A/m<SUP>2</SUP>. This new concept has the potential as a green energy harvesting technique where a broad range of material candidates and device configurations could be used.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Quantum mechanical tunneling at triboelectrically charged interface through ultrathin oxide layer is demonstrated. </LI> <LI> Tribo-tunneling is found to be a universal phenomenon in MIS frictional contact system. </LI> <LI> High current density <I>J</I> of 5 A/m<SUP>2</SUP> is experimentally measured in doped silicon materials at macroscale. </LI> <LI> Ultrahigh C-AFM <I>J</I> of 10<SUP>4</SUP> A/m<SUP>2</SUP> is observed due to the nano-size probe-induced high electric field. </LI> <LI> This method can be used as cost-effective triboelectric DC current generator, due to easily available silicon wafers with native oxide. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Tectono-magmatic evolution of the Mesozoic granodiorite and their diorite enclaves in Shulan Area, Jilin, China

Mengmeng Li,Jingdang Liu,Tianyi Liang,Chen Li,Dejun Bao 한국지질과학협의회 2022 Geosciences Journal Vol.26 No.1

The Mesozoic granodiorite and their diorite enclaves in the Shulan area have been investigated to understand the petrographic characteristics and elemental geochemistry and to further interpret the petrogenesis and paleotectonic environment. The petrography, mineral component, zircon U-Pb age, and major and trace element contents of 9 granodiorite host rock samples and 9 diorite enclave samples were analyzed. Results show host rock and the enclave both present of medium-fine subhedral and porphyritic. The main rock-forming minerals of host rocks are plagioclase (57–60%), quartz (25–30%), and K-feldspar (6–13%), whereas the main rock-forming minerals of enclaves are plagioclase (65–83%), amphibole (3–20%), and biotite (5–25%). Zircon U-Pb dating results show that the weighted-mean 206Pb/238U ages of the granodiorite host rock and the diorite enclave are 168.1 ± 1.6 Ma and 181.0 ± 1.0 Ma, respectively. The SiO2 contents of the host rocks and enclaves are 61.95–64.86% and 51.12–59.32%, respectively. Their K2O/Na2O ratios are 0.51–1.24 and 0.41–1.02; aluminum saturation index A/CNK [Al2O3/(CaO + Na2O + K2O) molar ratio] are between 0.80–1.14 and 0.70–0.98 and A/NK [Al2O3/(Na2O + K2O) molar ratio] are 1.48–1.97 and 1.47–2.11, indicating a medium-high-K calc-alkaline series and a metaluminous series. The chondrite-normalized rare earth element (REE) patterns of both host rock and enclave samples show a right-dip model, but the Eu ratios of the host rock samples show weak negative anomalies, whereas the Eu ratios of the enclave samples show distinctive negative anomalies. The δEu [δEu = EuN/sqrt(SmN × GdN)] averages of both host rock and enclave samples are 0.75 and 0.63, respectively. The primary mantle normalized trace element patterns shows the enrichment of Rb, Th, U, La, Zr, Hf and Li and the depletion of Nb and Sm in the granodiorite host rocks, whereas enriched Rb, U, La, Pr, Nd, Zr, Hf, and Li and depleting Ba, Nb, Sr, Sm, and Eu are presented in the diorite enclaves. The REE, trace element patterns and the other geochemical indices indicate both granodiorite and diorite were derived from partial melting of pre-existent basaltic materials with a minor contribution of mantle materials. Host rocks and enclaves were formed in the same subduction-related paleotectonic environment, but in different stages of magma evolution. The subduction triggered the delamination of the lithosphere, causing upwelling of the asthenosphere and partial melting of the crust, forming the magmatic precursors of both kinds of rocks.

Characterization of Volatile Compounds in Donkey Meat by Gas Chromatography–Ion Mobility Spectrometry (GC–IMS) Combined with Chemometrics

Mengmeng Li,Mengqi Sun,Wei Ren,Limin Man,Wenqiong Chai,Guiqin Liu,Mingxia Zhu,Changfa Wang 한국축산식품학회 2024 한국축산식품학회지 Vol.44 No.1

Volatile compounds (VOCs) are an important factor affecting meat quality. However, the characteristic VOCs in different parts of donkey meat remain unknown. Accordingly, this study represents a preliminary investigation of VOCs to differentiate between different cuts of donkey meat by using headspace–gas chromatography–ion mobility spectrometry (HS–GC–IMS) combined with chemometrics analysis. The results showed that the 31 VOCs identified in donkey meat, ketones, alcohols, aldehydes, and esters were the predominant categories. A total of 10 VOCs with relative odor activity values ≥1 were found to be characteristic of donkey meat, including pentanone, hexanal, nonanal, octanal, and 3-methylbutanal. The VOC profiles in different parts of donkey meat were well differentiated using three- and two-dimensional fingerprint maps. Nine differential VOCs that represent potential markers to discriminate different parts of donkey meat were identified by chemometrics analysis. These include 2-butanone, 2- pentanone, and 2-heptanone. Thus, the VOC profiles in donkey meat and specific VOCs in different parts of donkey meat were revealed by HS–GC–IMS combined with chemometrics, whcih provided a basis and method of investigating the characteristic VOCs and quality control of donkey meat.