Short-Term Rental Regulation and House Sharing Behavior: Evidence From Airbnb.com

The controversial short-term rental (STR) industry and the relevant STR regulation have been in the spotlight in recent years. Despite all the pros and cons of regulating the STR industry, yet it is unclear what the real effects of the STR regulation are. This study seeks to shed light on the questions regarding how the city STR regulation and should be conceived as well as what the outcomes of the regulation implementation are. We employ a comprehensive data set assembled from multiple resources to analyze the effects of the STR regulation from different geographic levels. Indeed, STR regulation turns out to be effective in improving the STR business. Registration requirement would encourage people from affluent neighborhoods to list their properties online. And internal requirements of the listed properties are critical in preventing listings from those non-affluent neighborhoods. At the clause level, the clauses vary in their effects in different types of neighborhoods. The clause specifically requiring listing to achieve certain standards would be more efficient in crowding out the listings with low quality from the STR market. STR regulation would be able to raise the quality of the listings online and standardize the listing process. Consequently, STR regulation would reduce the information-based uncertainties exist in the online STR mediatory platforms. Overall, the results suggest that STR regulation helps release the “lemon problems” in the STR market by encouraging listings with good quality while crowd out the “bad apples” from the platforms by adjusting the STR business in different types of neighborhoods

SabR enhances nikkomycin production via regulating the transcriptional level of sanG, a pathway-specific regulatory gene in Streptomyces ansochromogenes

<p>Abstract</p> <p>Background</p> <p><it>sabR </it>is a pleiotropic regulatory gene which has been shown to positively regulate the nikkomycin biosynthesis and negatively affect the sporulation of <it>Streptomyces ansochromogenes</it>. In this study, we investigate the mechanism of SabR on modulating nikkomycin production in <it>Streptomyces ansochromogenes</it>.</p> <p>Results</p> <p>The transcription start point of <it>sabR </it>was determined by high-resolution S1 nuclease mapping and localized at the nucleotide T at position 37 bp upstream of the potential <it>sabR </it>translation start codon (GTG). Disruption of <it>sabR </it>enhanced its own transcription, but retarded the nikkomycin production. Over-expression of <it>sabR </it>enhanced nikkomycin biosynthesis in <it>Streptomyces ansochromogenes</it>. EMSA analysis showed that SabR bound to the upstream region of <it>sanG</it>, but it did not bind to the upstream region of its encoding gene (<it>sabR</it>), <it>sanF </it>and the intergenic region between <it>sanN </it>and <it>sanO</it>. DNase 1 footprinting assays showed that the SabR-binding site upstream of <it>sanG </it>was 5'-CTTTAAGTCACCTGGCTCATTCGCGTTCGCCCAGCT-3' which was designated as SARE. Deletion of SARE resulted in the delay of nikkomycin production that was similar to that of <it>sabR </it>disruption mutant.</p> <p>Conclusions</p> <p>These results indicated that SabR modulated nikkomycin biosynthesis as an enhancer via interaction with the promoter region of <it>sanG</it>, and expanded our understanding about regulatory cascade in nikkomycin biosynthesis.</p

Investigation into the nature behind the interesting half levitation behavior of claimed superconductor LK-99

A recent article published by Lee et.al. claimed to have successfully achieved superconductivity at room temperature (RT) has become a topical issue. Besides the research paper, Lee and his team provided a demonstration video of LK-99 half levitating (HL) on a magnet. Such interesting HL appearance has drawn tremendous sensation both in academia and the network. However, the true identity of LK-99 still remains unclear, i.e., whether the HL behavior can necessarily indicate the diamagnetism behavior of the sample. Here, we fabricated our own LK-99 samples following the procedures reported by Lee et al. We found quite a few sample pieces showing the typical HL that is similar to those reported. Meanwhile, oxidation during the sample preparation was found to deleterious to acquiring HL in the sample, while furnace cooling or water quenching in the last step revealed little effect. However, our careful observations indicated that those HL pieces are more likely simple ferromagnetic. Then we conducted a comprehensive study on the behavior patterns of typical diamagnetism and ferromagnetic substances interacting with a Nd2Fe14B magnet, and provided instructions to distinguish the characteristics between ferromagnetic and diamagnetic to prevent misunderstanding of LK-99 like levitation behavior

Highly dispersed and ultrafine Co3O4@N-doped carbon catalyst derived from metal-organic framework for efficient oxygen reduction reaction

932-937Electrocatalysts are composed of transition metal/metal oxide and N-doped carbon can overcome the sluggish kinetics of oxygen reduction reactio. Herein, the Co3O4/ketjen black (KB)@MOF-derived with uniformly dispersed and ultrafine Co3O4 nanoparticles (1-5 nm) are synthesized by a facile in-situ method and subsequent mild pyrolysis process. It exhibits enhanced activity with onset potential of 0.96 V (vs. RHE) and a half-wave potential of 0.86 V (vs. RHE) in 0.1 M KOH solution, the excellent durability with E1/2 a small negative shift of 10 mV after 5000 continuous cycles and good methanol-tolerance property. The ultrahigh catalytic performance of Co3O4/KB@MOF-derived can be ascribed to the small particle size range of 1-5 nm of Co3O4, as well as the strong interaction between the in-situ formed N-Co3O4 active sites and substrate under the mild calcination temperature. Above all, these indicate that the as-prepared Co3O4/KB@MOF-derived may be a good alternative to commercial Pt-based catalysts

Efficacy and safety of a combination of miglitol, metformin and insulin aspart in the treatment of type 2 diabetes

Purpose: To study the clinical effect of combining insulin aspart with different drugs in the treatment oftype 2 diabetes mellitus (T2DM).Methods: Two hundred and thirty-seven T2DM patients admitted to the Endocrinology Department of the Second Affiliated Hospital of Kunming Medical University from March to September 2018 were selected as subjects in this study. Miglitol and metformin were used in combination with insulin aspart in the treatment of T2DM. In addition, data on the effectiveness and safety of different treatment options,such as patient’s weight, waist circumference, blood glucose indicators, indices of heart, liver and kidney functions, and incidence of complications were recorded and compared between the two groups.Results: The use of a combination of miglitol and insulin aspart produced an excellent hypoglycaemic effect, and it significantly reduced the incidence of sensory neuropathy in the eyes and distal limbs (p &lt; 0.05). The use of combination of metformin and insulin aspart effectively protected the heart and kidney, and prevented hypoglycaemia (p &lt; 0.05).Conclusion: These results suggest that treatment with a combination of miglitol and insulin aspart is suitable for patients with T2DM whose blood sugar levels are out of control, while combined treatment with metformin and insulin aspart is more suited for patients who desire to reduce blood sugar and blood lipids through weight loss, and patients with cardiac and renal insufficiency

CeO2 Nanowires Inserted into Reduced Graphene Oxide as Active Electrocatalyst for Oxygen Reduction Reaction

Fabrication of an interconnected and conductive nano-architecture is a prospective strategy to design a high-performance and low cost electrocatalyst for oxygen reduction reaction (ORR). Herein, a novel nano-architecture assembled by graphene nanosheets and CeO2 nanowires (NWs) with a hierarchical structure was developed by a facile hydrothermal process using ethanol/water as solvents without any organic additives. In this framework, graphene oxide (GO) was reduced to graphene and chemical bonding formed between the GO and CeO2 NWs in a hydrothermal process. The imbedded CeO2 NWs could prevent the restacking of the graphene sheets and improved the electrical conductivity of the hybrid catalyst. The effect of different ratios of GO to CeO2 NWs in the hybrid were studied. The GO3-CeO2 NWs composite exhibited better catalytic performance with slow attenuation and high limiting current density 3.55 and 1.99 times higher than CeO2 NWs and pure GO. The onset potential of GO3-CeO2 NWs is 0.13 V and 0.05 V positive shift from that of CeO2 NWs and pure GO, respectively, suggesting that the GO3-CeO2 NWs hybrid had an excellent stability and activity for ORR. It was found that CeO2 NWs served not only as an effective catalyst but also as an “oxygen buffer” to relieve oxygen insufficiency for ORR

Sulfonated microporous polymer membranes with fast and selective ion transport for electrochemical energy conversion and storage

Membranes with fast and selective transport of protons and cations are required for a wide range of electrochemical energy conversion and storage devices, such as proton-exchange membrane (PEM) fuel cells and redox flow batteries. Here we report a new approach to designing solution-processable ion-selective polymer membranes with both intrinsic microporosity and ion-conductive functionality. This was achieved by synthesizing polymers with rigid and contorted backbones, which incorporate hydrophobic fluorinated and hydrophilic sulfonic acid functional groups, to produce membranes with negatively-charged subnanometer-sized confined ionic channels. The facilitated transport of protons and cations through these membranes, as well as high selectivity towards nanometer-sized redox-active molecules, enable efficient and stable operation of an aqueous alkaline quinone redox flow battery and a hydrogen PEM fuel cell. This membrane design strategy paves the way for producing a new-generation of ion-exchange membranes for electrochemical energy conversion and storage applications