Graphene oxide conjugated with polymers: a study of culture condition to determine whether a bacterial growth stimulant or an antimicrobial agent?

BACKGROUND: The results showed that the deciding factor is the culture medium in which the bacteria and the graphene oxide (GO) are incubated at the initial manipulation step. These findings allow better use of GO and GO-based materials more and be able to clearly apply them in the field of biomedical nanotechnology. RESULTS: To study the use of GO sheets applied in the field of biomedical nanotechnology, this study determines whether GO-based materials [GO, GO-polyoxyalkyleneamine (POAA), and GO-chitosan] stimulate or inhibit bacterial growth in detail. It is found that it depends on whether the bacteria and GO-based materials are incubated with a nutrient at the initial step. This is a critical factor for the fortune of bacteria. GO stimulates bacterial growth and microbial proliferation for Gram-negative and Gram-positive bacteria and might also provide augmented surface attachment for both types of bacteria. When an external barrier that is composed of GO-based materials forms around the surface of the bacteria, it suppresses nutrients that are essential to microbial growth and simultaneously produces oxidative stress, which causes bacteria to die, regardless of whether they have an outer-membrane-Gram-negative-bacteria or lack an outer-membrane-Gram-positive-bacteria, even for high concentrations of biocompatible GO-POAA. The results also show that these GO-based materials are capable of inducing reactive oxygen species (ROS)-dependent oxidative stress on bacteria. Besides, GO-based materials may act as a biofilm, so it is hypothesized that they suppress the toxicity of low-dose chitosan. CONCLUSION: Graphene oxide is not an antimicrobial material but it is a general growth enhancer that can act as a biofilm to enhance bacterial attachment and proliferation. However, GO-based materials are capable of inducing ROS-dependent oxidative stress on bacteria. The applications of GO-based materials can clearly be used in antimicrobial surface coatings, surface-attached stem cells for orthopedics, antifouling for biocides and microbial fuel cells and microbial electro-synthesis.

Synthesis and Characterization of MnIn2S4/Single-Walled Carbon Nanotube Composites as an Anode Material for Lithium-Ion Batteries.

In this study, we synthesized a transition metal sulfide (TMS) with a spinel structure, i.e., MnIn2S4 (MIS), using a two-step hydrothermal and sintering process. In the context of lithium-ion battery (LIB) applications, ternary TMSs are being considered as interesting options for anode materials. This consideration arises from their notable attributes, including high theoretical capacity, excellent cycle stability, and cost-effectiveness. However, dramatic volume changes result in the electrochemical performance being severely limited, so we introduced single-walled carbon nanotubes (SWCNTs) and prepared an MIS/SWCNT composite to enhance the structural stability and electronic conductivity. The synthesized MIS/SWCNT composite exhibits better cycle performance than bare MIS. Undergoing 100 cycles, MIS only yields a reversible capacity of 117 mAh/g at 0.1 A/g. However, the MIS/SWCNT composite exhibits a reversible capacity as high as 536 mAh/g after 100 cycles. Moreover, the MIS/SWCNT composite shows a better rate capability. The current density increases with cycling, and the SWCNT composite exhibits high reversible capacities of 232 and 102 mAh/g at 2 A/g and 5 A/g, respectively. Under the same conditions, pristine MIS can only deliver reversible capacities of 21 and 4 mAh/g. The results indicate that MIS/SWCNT composites are promising anode materials for LIBs.

Cryptococcal granulomas of basal ganglia due to Cryptococcus neoformans in a cat: a case report and literature review.

A 3-year-old spayed female domestic short-haired cat presented with a head turning to the left, circling to the right, seizures, and opisthotonos for approximately one month. Neurological examination revealed a deficit in the postural reaction of the left limbs and visual abnormalities. Forensic computed tomography revealed a hyperattenuating round mass of 1.3 cm diameter with a hypoattenuating center in the right hemisphere. Histopathology showed multifocal granuloma lesions with the major mass mostly affecting the right basal ganglia. Cryptococcus neoformans variety grubii molecular type VNI/ST31 was isolated from the cryptococcal granulomas. This report highlights the epidemiological distribution and differential diagnosis of a feline central nervous system cryptococcosis caused by C. neoformans that occurred in an Asian country.

Co/ZnO/Nitrogen-Doped Carbon Composite Anode Derived from Metal Organic Frameworks for Lithium Ion Batteries.

Through high-temperature sintering and carbonization, two Co/ZnO nitrogen-doped porous carbon (NC) composites derived from ZIF-8 and ZIF-67 were manufactured for use as anodes for Li ion batteries: composite-type Co/ZnO-NC and core-shell-type Co@ZnO-NC. X-ray diffraction analysis, scanning electron microscopy, and the Brunauer-Emmett-Teller (BET) method were performed to identify the pore distribution and surface morphology of these composites. The findings of the BET method indicated that the specific surface area of Co/ZnO-NC was 350 m2/g, which was twice that of Co@ZnO-NC. Electrochemical measurements revealed that Co@ZnO-NC and Co/ZnO-NC had specific capacities of over 400 mAh g-1 at a current density 0.2 A g-1 after 50 cycles. After 100 cycles, Co/ZnO-NC exhibited a reversible capacity of 411 mAh g-1 at a current density of 0.2 A g-1 and Co@ZnO-NC had a reversible capacity of 246 mAh g-1 at a current density of 0.2 A g-1. The results indicated that Co/ZnO-NC exhibited superior electrochemical performance to Co@ZnO-NC as a potential anode for use in Li ion batteries.

Facile and Green Process to Synthesize a Three-Dimensional Network Few-Layer Graphene/Carbon Nanotube Composite for Electromagnetic Interference Shielding.

We propose an environmentally friendly liquid exfoliation approach and subsequent freeze-drying process for constructing a three-dimensional (3D) carbon-based network by using few-layer graphene (FLG) and carbon nanotubes (CNTs) for electromagnetic interference (EMI) shielding applications. Systematic characterizations-such as X-ray diffraction, scanning electron microscopy, and transmission electron microscopy-as well as Raman characterization and EMI shielding tests were performed. The results indicated that the as-synthesized 3D-FLG/CNT composite obtained through the freeze-drying process exhibited excellent electromagnetic interference shielding. The shielding effect of FLG could be improved from 15 to 22 dB by introducing CNTs. The CNTs inhibited restacking of FLG in the structure. We also compared two drying processes: oven drying and freeze-drying. The freeze-drying technique markedly improved the shielding effect of FLG/CNTs from 22 to 36 dB. The composition-optimized 3D-FLG/CNT composite could be a candidate material for use in EMI shielding.

Industrial Silicon-Wafer-Wastage-Derived Carbon-Enfolded Si/Si-C/C Nanocomposite Anode Material through Plasma-Assisted Discharge Process for Rechargeable Li-Ion Storage.

Silicon is a promising anode material for high-performance Li-ion batteries as a result of its high theoretical specific capacity and elemental abundance. Currently, the commercial application of the Si-based anode is still restricted by its large volume changes during the lithiation cycles and low electrical conductivity. To address these issues, we demonstrate a facile plasma-assisted discharge process to anchor nano-sized Si particles into methanol with quick quenching. After the subsequent sintering process, we obtained a Si/SiC/C composite (M-Si). The unique structure not only allowed for the electrolyte infiltration to enhance lithium ion diffusion during charge and discharge process, but also buffered the volume expansion of silicon particles to enhance the rate capability and cycle stability. The M-Si cell electrochemical results exposed good Li-ion storage performance compared to that of the bare Si used cell (B-Si). The electrode cell consisting of M-Si exhibited remarkable enhanced cyclic stability and sustained the reversible specific capacity of 563 mAhg-1 after 100 cycles, with a coulombic efficiency of 99% at a current density of 0.1C, which is higher than that of the B-Si electrode cell that was used. Hence, the as-prepared Si/SiC/C composite is an efficient anode material for Li-ion battery applications. Moreover, these results indicate that the novel plasma-assisted discharge technique will bring a potential durable methodology to produce novel high-performance electrode materials for future advanced large-scale energy-storage applications.

Corrigendum: An Ethnobotanical Study of Medicinal Plants in Kinmen.

[This corrects the article DOI: 10.3389/fphar.2021.681190.].

Mitochondrial DNA methylation profiling of the human prefrontal cortex and nucleus accumbens: correlations with aging and drug use.

BACKGROUND: Despite the brain's high demand for energy, research on its epigenetics focuses on nuclear methylation, and much of the mitochondrial DNA methylation remains seldom investigated. With a focus on the nucleus accumbens (NAcc) and the prefrontal cortex (PFC), we aimed to identify the mitochondrial methylation signatures for (1) distinguishing the two brain areas, (2) correlating with aging, and (3) reflecting the influence of illicit drugs on the brain. RESULT: We collected the brain tissue in the NAcc and the PFC from the deceased individuals without (n = 39) and with (n = 14) drug use and used whole-genome bisulfite sequencing to cover cytosine sites in the mitochondrial genome. We first detected differential methylations between the NAcc and the PFC in the nonusers group (P = 3.89 × 10-9). These function-related methylation differences diminished in the drug use group due to the selective alteration in the NAcc. Then, we found the correlation between the methylation levels and the chronological ages in the nonusers group (R2 = 0.34 in the NAcc and 0.37 in the PFC). The epigenetic clocks in illicit drug users, especially in the ketamine users, were accelerated in both brain regions by comparison with the nonusers. Finally, we summarized the effect of the illicit drugs on the methylation, which could significantly differentiate the drug users from the nonusers (AUC = 0.88 in the NAcc, AUC = 0.94 in the PFC). CONCLUSION: The mitochondrial methylations were different between different brain areas, generally accumulated with aging, and sensitive to the effects of illicit drugs. We believed this is the first report to elucidate comprehensively the importance of mitochondrial DNA methylation in human brain.

An Ethnobotanical Study of Medicinal Plants in Kinmen.

Kinmen is an outlying island that has the richest plant resources in Taiwan. The objective of this study was to record the methods that people in Kinmen use medicinal plants and to analyze the cultural characteristics of their use. Field investigations were carried out in various towns and villages in Kinmen, and 80 respondents were included in the survey. The search for respondents was conducted through local elderly people and medicinal plant groups. Semi-structured interviews were conducted with the local people to obtain their knowledge of medicinal plants and how they disseminate this information. Informed consent was obtained prior to the interviews, and the following was determined: plant use value (UV), frequency of citation (FC), and factor of informant consensus (Fic). These parameters were used to quantify the data and measure the agreement among the respondents on using plants to treat different diseases. Finally, the survey results were compared with the representative ethnobotanical literature in neighboring areas to evaluate the similarity between plant usage in Kinmen and neighboring areas as well as to determine whether there are new species or novel usages in the study area. In the Kinmen area, phytotherapy is generally used by elderly people with low educational attainments. According to the survey results, 83 medicinal plants belonging to 48 families were collected. These medicinal plants were mainly distributed in the Compositae, Lamiaceae, and Solanaceae families. Eighteen novel uses that have not been previously documented were found, four of which were related to newly recorded medicinal plant species in the Kinmen area. The results showed that 93.98 and 65.06% of the species collected in the present study were also recorded in literature from Taiwan and Fujian, respectively. This study showed that Kinmen's ethnobotanical knowledge is closely related to the Catalogue of Medicinal Plant Resources in Taiwan, and local people indeed shared similar uses of medicinal species with people in Taiwan and Fujian (46.99%). The results from this study highlighted the importance of traditional medicine in the Kinmen area, where people have a specific understanding of using medicinal plants and communication with people in Taiwan and Fujian Province in China. It was found that Kinmen shares ethnobotanical knowledge with Taiwan and Fujian.

Effect of Polyaniline on Sulfur/Sepiolite Composite Cathode for Lithium-Sulfur Batteries.

Composite materials with a stable network structure consisting of natural sepiolite (Sp) powders (both sieved sepiolite and post-treated sepiolite), sulfur(S), and conductive polymer Polyaniline (PAni) have been successfully synthesized using a simple heat treatment. The morphology of composites illustrates that the sepiolite is composed of many needle-like fibrous clusters. The initial discharge capacity of the post-treated sepiolite/sulfur/PAni composite is about 1230 mA h g-1 at 0.1 C, and it remains at 826 mA h g-1 even after 40 cycles with the corresponding coulombic efficiency above 97%. Such performance is attributed to the specific porous structure, outstanding adsorption characteristics, and excellent ion exchange capability of sepiolite, as well as the excellent conductivity of PAni. In addition, the PAni coating has a pinning effect on sulfur, which influences the consumption of the active mass and enhances the cycling constancy and the coulombic efficiency of the composite material at elevated current rates.

High Capacity Prismatic Type Layered Electrode with Anionic Redox Activity as an Efficient Cathode Material and PVdF/SiO2 Composite Membrane for a Sodium Ion Battery.

A prismatic type layered Na2/3Ni1/3Mn2/3O2 cathode material for a sodium ion battery is prepared via two different methods viz., the solid state and sol-gel method with dissimilar surface morphology and a single phase crystal structure. It shows tremendous electrochemical chattels when studied as a cathode for a sodium-ion battery of an initial specific discharge capacity of 244 mAh g-1 with decent columbic efficiency of 98% up to 250 cycles, between the voltage range from 1.8 to 4.5 V (Na+/Na) at 0.1 C under room temperature. It is much higher than its theoretical value of 173 mAh g-1 and also than in the earlier reports (228 m Ah g-1). The full cell containing this material exhibits 800 mAh g-1 at 0.1 C and withstands until 1000 cycles with the discharge capacity of 164 mAh g-1. The surpassing capacity was expected by the anionic (oxygen) redox process, which elucidates the higher capacity based on the charge compensation phenomenon.

Superior Ionic Transferring Polymer with Silicon Dioxide Composite Membrane via Phase Inversion Method Designed for High Performance Sodium-Ion Battery.

Superior sodium-ion-conducting polymer poly(vinyledene fluoride)-silicon dioxide (PVdF-SiO2) composite separator membrane was prepared via simple phase inversion method, which is a suitable alternative conventional polypropylene membrane. Basically, PVdF is the promising for use as high porous polymer electrolyte membrane due to its high dielectric constant ( = 8.4). In this work, we prepared a composite membrane using PVdF-SiO2 via phase inversion method. This work was systematically studied towards the morphology, porosity, and electrochemical properties of as prepared membrane. The electrolyte uptake capability of separator membrane tested with 1 M NaPF6 electrolyte solution and temperature-dependent ionic conduction test were performed at various temperatures. This membrane exhibits higher ionic conductivity of 4.7 × 10-2 S cm-1 at room temperature. The physical properties were analyzed by X-ray diffraction, FT-IR, and FE-SEM micrographs analyses. The electrochemical performances with impedance analysis carried for prepared membrane with the as-prepared sodium P2-type cathode material. The material showed an initial discharge capacity of 178 mAh g-1 at 0.1 C between 2 and 4 V with 98% columbic efficiency and 81% capacity retention after 50 cycles upon using the as-prepared PVdF-SiO2 composite separator membrane.

Ethnobotanical Survey of Natural Galactagogues Prescribed in Traditional Chinese Medicine Pharmacies in Taiwan.

Natural medicinal materials have been used to promote breast milk secretion. Here, we investigated the natural medicinal materials prescribed in traditional Chinese medicine (TCM) pharmacies across Taiwan to induce lactation. We collected medicinal materials from 87 TCM pharmacies, identified them in the prescriptions, and analyzed their drug contents. We examined their botanical origins, biological classifications, traditional usage, and modern pharmacological properties. We used the TCM Inheritance Support System to identify core medicinal materials in galactogenous prescriptions. We collected 81 medicinal materials from 90 galactogenous prescriptions. Leguminosae accounted for 12%, whereas Apiaceae accounted for 7% of all materials examined. The primary medicinal plant parts used were roots and seeds. Nineteen frequently used medicinal materials had a relative frequency of citation of greater than or equal to 0.2. According to their efficacy, 58% were warm, 54% were sweet, and 63% were tonifying; 74% of the frequently used medicinal materials have been showed efficacy against breast cancer. The primary core medicinal material was Angelica sinensis (Oliv.) Diels, whereas the secondary core medicinal materials were Tetrapanax papyrifer (Hook.) K. Koch and Hedysarum polybotrys Hand.-Mazz. Most galactogenous prescriptions consisted of multiple materials from Leguminosae and Apiaceae. The mechanisms underlying galactogenous efficacy warrant further investigations.

Structural Design of Three-Dimensional Graphene/Nano Filler (Al2O3, BN, or TiO2) Resins and Their Application to Electrically Conductive Adhesives.

In this study, we designed a three-dimensional structure of electrically conductive adhesives (ECAs) by adding three different kinds of nano filler, including BN, TiO2, and Al2O3 particles, into a few-layered graphene (FLG)/polymer composite to avoid FLG aggregation. Three different lateral sizes of FLG (FLG3, FLG8, and FLG20) were obtained from graphite (G3, G8, and G20) by a green, facile, low-cost, and scalable jet cavitation process. The corresponding characterizations, such as Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM), verified the successful preparation of graphene flakes. Based on the results of four-point probe measurements, FLG20 demonstrated the lowest sheet resistance value of ~0.021 Ω/■. The optimized ECAs' composition was a 60% solid content of FLG20 with the addition 2 wt.% of Al2O3. The sheet resistance value was as low as 51.8 Ω/■, which was a reduction of 73% compared to that of pristine FLG/polymer. These results indicate that this method not only paves the way for the cheaper and safer production of graphene, but also holds great potential for applications in energy-related technologies.

Carbon Loaded Nano-Designed Spherically High Symmetric Lithium Iron Orthosilicate Cathode Materials for Lithium Secondary Batteries.

In the present study, Li2FeSiO4 (LFS) cathode material has been prepared via a modified polyol method. The stabilizing nature of polyol solvent was greatly influenced to reduce the particle size (~50 nm) and for coating the carbon on the surface of the as-mentioned materials (~10 nm). As-prepared nano-sized Li2FeSiO4 material deliver initial discharge capacity of 186 mAh·g-1 at 1C with the coulombic efficiency of 99% and sustain up to 100 cycles with only 7 mAh·g-1 is the difference of discharge capacity from its 1st cycle to 100th cycle. The rate performance illustrates the discharge capacity 280 mAh·g-1 for lower C-rate (C/20) and 95 mAh·g-1 for higher C-rate (2C).

Risk of Cancer after Lower Urinary Tract Infection: A Population-Based Cohort Study.

To investigate the association among lower urinary tract infection (UTI), the type and timing of antibiotic usage, and the subsequent risk of developing cancers, especially genitourinary cancers (GUC), in Taiwan. This retrospective population-based cohort study was conducted using 2009⁻2013 data from the Longitudinal Health Insurance Database. This study enrolled patients who were diagnosed with a UTI between 2010 and 2012. A 1:2 propensity score-matched control population without UTI served as the control group. Multivariate analysis with a multiple Cox regression model was applied to analyze the data. A total of 38,084 patients with UTI were included in the study group, and 76,168 participants without UTI were included in the control group. The result showed a higher hazard ratio of any cancer in both sexes with UTI (for males, adjusted hazard ratio (aHR) = 1.32; 95% confidence interval (CI) = 1.12⁻1.54; for females, aHR = 1.21; 95% CI = 1.08⁻1.35). Patients with UTI had a higher probability of developing new GUC than those without UTI. Moreover, the genital organs, kidney, and urinary bladder of men were significantly more affected than those of women with prior UTI. Furthermore, antibiotic treatment for more than 7 days associated the incidence of bladder cancer in men (7⁻13 days, aHR = 1.23, 95% CI = 0.50⁻3.02; >14 days, aHR = 2.73, CI = 1.32⁻5.64). In conclusion, UTI is significantly related to GUC and may serve as an early sign of GUC, especially in the male genital organs, prostate, kidney, and urinary bladder. During UTI treatment, physicians should cautiously prescribe antibiotics to patients.

Impacts of AURKA Genetic Polymorphism on Urothelial Cell Carcinoma Development.

Urothelial cell carcinoma (UCC) is the most common primary malignancy of the urinary system and the second-most common type of renal cell carcinoma. Aurora kinase A (AURKA), a serine/threonine kinase, has a critical role in centrosome duplication, spindle assembly checkpoint, and cytokinesis. Here, we determined the correlation between UCC susceptibility and AURKA polymorphisms. We used real-time polymerase chain reaction to compare the genotype distributions and allelic frequencies of four single-nucleotide polymorphisms (SNPs) of AURKA, namely rs1047972, rs2273535, rs2064863, and rs6024836, between 431 UCC cases and 862 healthy controls. Logistic regression models demonstrated that the G allele of rs2064863, a genetic polymorphism of AURKA, exhibited a significant protective effect against UCC among the 862 nonsmokers. Moreover, patients with rs2064863 G allele exhibited a slightly lower risk of lymph node metastasis and those with rs6024836 G allele exhibited a lower risk of distant metastases. Our study suggested that several variants of AURKA SNPs rs2064863 and rs6024836 may serve as critical predictors for the clinical status of UCC.

Facile and Green Synthesis of Graphene-Based Conductive Adhesives via Liquid Exfoliation Process.

In this study, we report a facile and green process to synthesize high-quality and few-layer graphene (FLG) derived from graphite via a liquid exfoliation process. The corresponding characterizations of FLG, such as scanning electron microscopy (SEM), transmission electron microscope (TEM), atomic force microscopy (AFM) and Raman spectroscopy, were carried out. The results of SEM show that the lateral size of as-synthesized FLG is 1⁻5 µm. The results of TEM and AFM indicate more than 80% of graphene layers is <10 layers. The most surprising thing is that D/G ratio of graphite and FLG are 0.15 and 0.19, respectively. The result of the similar D/G ratio demonstrates that little structural defects were created via the liquid exfoliation process. Electronic conductivity tests and resistance of composite film, in terms of different contents of graphite/polyvinylidene difluoride (PVDF) and FLG/PVDF, were carried out. Dramatically, the FLG/PVDF composite demonstrates superior performance compared to the graphite/PVDF composite at the same ratio. In addition, the post-sintering process plays an important role in improving electronic conductivity by 85%. The composition-optimized FLG/PVDF thin film exhibits 81.9 S·cm-1. These results indicate that the developed FLG/PVDF composite adhesives could be a potential candidate for conductive adhesive applications.

Investigation of length heteroplasmy in mitochondrial DNA control region by massively parallel sequencing.

Accurate sequencing of the control region of the mitochondrial genome is notoriously difficult due to the presence of polycytosine bases, termed C-tracts. The precise number of bases that constitute a C-tract and the bases beyond the poly cytosines may not be accurately defined when analyzing Sanger sequencing data separated by capillary electrophoresis. Massively parallel sequencing has the potential to resolve such poor definition and provides the opportunity to discover variants due to length heteroplasmy. In this study, the control region of mitochondrial genomes from 20 samples was sequenced using both standard Sanger methods with separation by capillary electrophoresis and also using massively parallel DNA sequencing technology. After comparison of the two sets of generated sequence, with the exception of the C-tracts where length heteroplasmy was observed, all sequences were concordant. Sequences of three segments 16184-16193, 303-315 and 568-573 with C-tracts in HVI, II and III can be clearly defined from the massively parallel sequencing data using the program SEQ Mapper. Multiple sequence variants were observed in the length of C-tracts longer than 7 bases. Our report illustrates the accurate designation of all the length variants leading to heteroplasmy in the control region of the mitochondrial genome that can be determined by SEQ Mapper based on data generated by massively parallel DNA sequencing.

Efficient two-photon luminescence for cellular imaging using biocompatible nitrogen-doped graphene quantum dots conjugated with polymers.

Nitrogen-doped graphene quantum dot (N-GQD) nanomaterials conjugated with polyethylenimine (PEI)-polystyrene sulfonate (PSS)-anti-epidermal growth factor receptor (AbEGFR) antibody (N-GQD-PEI-PSS-AbEGFR) demonstrated impressive two-photon properties and stability, signifying that they can serve as an effective two-photon contrast agent in two-photon bioimaging. Furthermore, they provided high intensity, brightness, and signal-to-noise ratios at an ultra-low two-photon excitation (TPE) power level in an observation extending to a deep, three-dimensional depth.