895 research outputs found
Stacked-graphene layers as engineered solid-electrolyte interphase (SEI) grown by chemical vapour deposition for lithium-ion batteries
A multi-layer of stacked-graphene (8 layers of basal planes) grown by chemical vapour deposition (CVD) is introduced as an artificial solid electrolyte interphase (SEI) layer onto a transition metal oxide cathode for lithium-ion batteries. The basal planes are generally regarded as a strong physical barrier that prevents lithium-ion diffusion, although it is believed that a small number of lithium-ions can migrate through the defect sites of the stacked layers. Interestingly, the unique design of the stacked-graphene perpendicular to the basal planes not only effectively suppresses the formation of instable SEI layers, but also achieves a reasonable amount of battery charge capacities. To correctly understand the impact from the stacked design, we further studied the rate kinetics difference between slow cycles (0.125 C→0.250 C→0.400 C→0.125 C) and rapid cycles (C→2 C→3 C→C). We propose that the clap-net like design of the stacked-graphene could enable the effective conducting pathway for electron transport, while protecting the active material inside. The magnetic measurements reveal the efficient Li+ (de)intercalation into graphene-layers. The artificial SEI also renders the electrode/electrolyte interface more stable against dynamic rate changes. The present approach provides a particular advantage in developing high stability battery that can be utilized at various charge rates
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Label free biosensing with carbon nanotube transistors
As electronics reach nanometer size scales, new avenues of integrating biology and electronics become available. For example, nanoscale field-effect transistors have been integrated with single neurons to detect neural activity. Researchers have also used nanoscale materials to build electronic ears and noses. Another exciting development is the use of nanoscale biosensors for the point-of-care detection of disease biomarkers.
This thesis addresses many issues that are relevant for electrical sensing applications in biological environments. As an experimental platform we have used carbon nanotube field-effect transistors for the detection of biological proteins. Using this experimental platform we have probed many of properties that control sensor function, such as surface potentials, the response of field effect transistors to absorbed material, and the mass transport of proteins. Field effect transistor biosensors are a topic of active research, and were first demonstrated in 1962. Despite decades of research, the mass transport of proteins onto a sensor surface has not been quantified experimentally, and theoretical modeling has not been reconciled with some notable experiments. Protein transport is an important issue because signals from low analyte concentrations can take hours to develop. Guided by mass transport modeling we modified our sensors to demonstrate a 2.5 fold improvement in sensor response time. It is easy to imagine a 25 fold improvement in sensor response time using more advanced existing fabrication techniques. This improvement would allow for the detection of low concentrations of analyte on the order of minutes instead of hours, and will open the door point-of-care biosensors
Quantitative Microbiology of the Scalp in Non-Dandruff, Dandruff, and Seborrheic Dermatitis
The composition of the scalp microflora was assessed quantitatively in normal individuals and in patients with dandruff and seborrheic dermatitis, disorders characterized by increasing scalin. Three organisms were constantly found: (1) Pityrosporum, (2) aerobic cocci, and (3) Corynebacterium acnes. Pitrosporum (mainly Pityrosporum ovale) made up 46% of the total microflora in normals, 74% in dandruff, and 83% in seborrheic dermatitis. The geometric mean number of organisms per cm2 in non-dandruff subjects was 5.04 × 105; 9.22 × 105 in dandruff subjects; and 6.45 × 105 in those with seborrheic dermatitis. The cocci were dominantly Baird-Parkertype SII and no quantitative or qualitative change occurred in the scaling disorders. C. acnes comprised 26% of the flora on the normal scalp, 6% in dandruff, and only 1% in seborrheic dermatitis. These results differ significantly from previous reports which describe a much more complex microflora and suggest an etiologic role for microorganisms in dandruff
APC loss in breast cancer leads to doxorubicin resistance via STAT3 activation
Resistance to chemotherapy is one of the leading causes of death from breast cancer. We recently established that loss of Adenomatous Polyposis Coli (APC) in the Mouse Mammary Tumor Virus – Polyoma middle T (MMTV-PyMT) transgenic mouse model results in resistance to cisplatin or doxorubicin-induced apoptosis. Herein, we aim to establish the mechanism that is responsible for APC-mediated chemotherapeutic resistance. Our data demonstrate that MMTV-PyMT;ApcMin/+ cells have increased signal transducer and activator of transcription 3 (STAT3) activation. STAT3 can be constitutively activated in breast cancer, maintains the tumor initiating cell (TIC) population, and upregulates multidrug resistance protein 1 (MDR1). The activation of STAT3 in the MMTV-PyMT;ApcMin/+ model is independent of interleukin 6 (IL-6); however, enhanced EGFR expression in the MMTV-PyMT;ApcMin/+ cells may be responsible for the increased STAT3 activation. Inhibiting STAT3 with a small molecule inhibitor A69 in combination with doxorubicin, but not cisplatin, restores drug sensitivity. A69 also decreases doxorubicin enhanced MDR1 gene expression and the TIC population enhanced by loss of APC. In summary, these results have revealed the molecular mechanisms of APC loss in breast cancer that can guide future treatment plans to counteract chemotherapeutic resistance
Novel M4 Pediatrics Chief Program Utilizing Near-peer Teaching and Mentoring to Enhance Clerkship Curricula
Introduction: Near-peer teachers add many benefits to the academic, clinical performance, and enjoyment of near-peer learners in medical education. This enterprise describes and examines how the Creighton University School of Medicine M4 Pediatrics Chief Program fills a gap in medical education by offering an organized and formal methodology for near-peer teaching. The Creighton University M4 Pediatrics Chief Program utilizes select fourth year medical students to orient, teach basic clinical skills, mentor, and participate in curriculum development for the third year Pediatric clerkship students.
Methods: Third year students (n=43) in their Pediatrics clerkship from September 2020 to February 2021 completed surveys at the end of the clerkship to assess the quality and effectiveness of the M4 Pediatrics Chief Program.
Results: Students rated effectiveness of the Chiefs most highly as clerkship guides (4.29, SD=0.79), teachers (4.21, SD=0.92), and mentors (4.19, SD=0.75). Near-peer perspectives, education, provision of pertinent content, serving as a clerkship resource, and being a source of encouragement were the most beneficial aspects of the program. Students reported strong agreement all clerkships should have an M4 Chief Program (4.53, SD=0.88).
Discussion: Because of the positive reviews by the third years students, the M4 Pediatrics Chief Program is now a permanent part of the Pediatric Clerkship. Additionally, other third year clerkships at Creighton University School of Medicine are adopting this model. Finally, the M4 students acting as the chiefs gain valuable leadership and educational skills.
Conclusion: Based on positive perceptions of the “M4 Chief Program”, the authors recommend other medical schools consider initiating similar programs within their third year clerkships.https://digitalcommons.unmc.edu/chri_forum/1037/thumbnail.jp
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Measurement of high carrier mobility in graphene in an aqueous electrolyte environment
Graphene is a promising material for applications in aqueous electrolyte environments. To explore the impact of such environments on graphene's electrical properties, we performed Hall bar measurements on electrolyte-gated graphene. Assuming a Drude model, we find that the room temperature carrier mobility in water-gated, SiO₂-supported graphene reaches 7000 cm²/Vs, comparable to the best dry SiO₂-supported graphene devices. Our results show that the electrical performance of graphene is robust, even in the presence of dissolved ions that introduce an additional mechanism for Coulomb scattering
Complete Genome Sequence of Paraclostridium bifermentans DSM 14991
The complete genome sequence of Paraclostridium bifermentans was obtained by assembly of Illumina and Oxford Nanopore (ONT) reads. The sequence will enable study into the organism’s ability to biohydrogenate unsaturated acyl chains in the transformation of C20 polyunsaturated fatty acids (PUFAs) into the corresponding bioactive non-methylene-interrupted fatty acids (NMIFAs)
Negligible‐Pb‐Waste and Upscalable Perovskite Deposition Technology for High‐Operational‐Stability Perovskite Solar Modules
An upscalable perovskite film deposition method combining raster ultrasonic spray coating and chemical vapor deposition is reported. This method overcomes the coating size limitation of the existing stationary spray, single‐pass spray, and spin‐coating methods. In contrast with the spin‐coating method (>90% Pb waste), negligible Pb waste during PbI2 deposition makes this method more environmentally friendly. Outstanding film uniformity across the entire area of 5 cm × 5 cm is confirmed by both large‐area compatible characterization methods (electroluminescence and scattered light imaging) and local characterization methods (atomic force microscopy, scanning electron microscopy, photoluminescence mapping, UV–vis, and X‐ray diffraction measurements on multiple sample locations), resulting in low solar cell performance decrease upon increasing device area. With the FAPb(I0.85Br0.15)3 (FA = formamidinium) perovskite layer deposited by this method, champion solar modules show a power conversion efficiency of 14.7% on an active area of 12.0 cm2 and an outstanding shelf stability (only 3.6% relative power conversion efficiency decay after 3600 h aging). Under continuous operation (1 sun light illumination, maximum power point condition, dry N2 atmosphere with <5% relative humidity, no encapsulation), the devices show high light‐soaking stability corresponding to an average T80 lifetime of 535 h on the small‐area solar cells and 388 h on the solar module
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