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Understanding complex urban systems necessitates untangling the relationships between diverse urban elements such as population, infrastructure, and socioeconomic activities. Scaling laws are basic but effective rules for evaluating a city's internal growth logic and assessing its efficiency by investigating whether urban indicators scale with population. To date, only limited research has empirically explored the scaling relations between variables of urban mobility in mega-cities at an intra-urban scale of a few meters. Using multiple urban-sensed and human-sensed data, this study proposes a thorough framework for quantifying the scaling laws in a city. To begin, urban mobility networks are built by aggregating population flows using large-scale mobile phone tracking data. To demonstrate the spatiotemporal variability of urban mobility, various network-based mobility measures are proposed. Following that, three different features of urban mobility laws are exposed, explaining spatial agglomeration, spatial hierarchical structures, and the temporal growth process. The scaling correlations between urban indicators pertaining to socioeconomic features and infrastructure and a mobility-population measure are then quantified using multi-sourced urban-sensed data. Applying this framework to the case study of Shenzhen, China revealed (a) spatial travel heterogeneity, hierarchical spatial structures, and mobility growth, and (b) not only a robust sub-linear relationship between infrastructure volume and population, but also a sub-linear relationship for socioeconomic activity. The identified scaling laws, both in terms of mobility measures and urban indicators, provide a multi-faceted portrait of the spatio-temporal variations of urban settings, allowing us to better understand intra-urban developments and, consequently, provide critical policy evaluations and suggestions for improving intra-urban efficiency in the future. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) have received widespread interest for their high atomic efficiency, enriched active sites, excellent catalytic performance, and low cost. However, the agglomeration of single metal atoms and the use of inactive additives for affixing powdery SACs on planar electrodes may reduce the density of active sites, diminish the charge transport to active sites, and thus suppress their performance. Herein, a series of metal–nitrogen–carbon single‐atom aerogels (M‐SAAs, M: Cu, Ni, Au, Ru) are synthesized via a universal strategy, in which the merits of metal organic frameworks and carbon aerogels are perfectly combined to prevent the agglomeration of single metal atoms and overcome the problem of poor electrical conductivity. The as‐prepared M‐SAAs can be directly employed as self‐supporting electrodes for the electrochemical dechlorination of 1,2‐dichloroethane, and outstanding activity and stability are observed. Significantly, the Cu‐SAA with abundant Cu−N4 sites shows an extraordinarily high ethylene production rate of 446 µmol h−1, with a selectivity of 99% and Faradaic efficiency of 64%. Moreover, theoretical calculations are performed to demonstrate the selectivity and activity of different metal active sites. This study provides a new strategy to exploit highly effective SACs and offers an intensive insight into the mechanism of electrochemical dechlorination reactions. [ABSTRACT FROM AUTHOR]

The electrocatalytic nitrogen reduction reaction (e-NRR), an eco-friendly and economical approach to convert nitrogen to ammonia under mild conditions, has received widespread attention in recent years. Defect engineering has been illustrated to be an effective strategy to improve the catalytic activity and selectivity of electrocatalysts via changing the electronic states as well as creating additional active sites for reduction reactions. Thus far, various approaches have been adopted to tune the physical and chemical properties of catalyst materials by means of inducing defects of different types and varying their concentrations or locations in host materials. In this review, the mechanisms and design principles of defective electrocatalysts for the NRR are introduced, and the refined synthesis and characterization techniques of defect engineering are systematically summarized. Based on the recent advances in defect engineering of electrocatalysts for the NRR, the roles of various defect states, such as vacancies and the amorphous phase, in the catalytic enhancement mechanism are comprehensively discussed. Finally, perspectives on the challenges and opportunities in developing new cost-effective and high-efficiency NRR catalysts for practical applications are outlined. [ABSTRACT FROM AUTHOR]

Abstract: A PCR detection based on 16S–23S rDNA internal transcribed spacer (ITS) of Klebsiella pneumoniae was developed in the present study. Nineteen different ITS sequences were amplified from 6 strains of K. pneumoniae by universal primers. By sequencing and alignment of these sequences to the other homologous in GenBank, species-specific primers of K. pneumoniae, Pf/Pr1 and Pf/Pr2, were designed for amplification of the ITS sequence from the operon containing tDNAAla and tDNAIle . Ten type strains and 21 isolates of K. pneumoniae were positive to the PCR detection, and all of the non-K. pneumoniae reference strains (79 strains) were negative. The enrichment was performed in this procedure with a modified growth media to enrich K. pneumoniae from 1.5 CFU/100 g infant formula to about 105 CFU/ml in 900 ml of the media. Combination of the enrichment, with the PCR assay can detect 1.5 CFU/100 g infant formula of K. pneumoniae within 48 h. Furthermore, K. pneumoniae strains KPE050803 and KPE 050830 were identified by this method in 63 infant formula samples. [Copyright &y& Elsevier]

Abstract: Enterobacter sakazakii is an emerging pathogen that causes meningitis, bacteremia, sepsis, and necrotizing enterocolitis in neonates and children. Powdered milk-based infant formulas have been associated with the E. sakazakii-related outbreaks in premature or other immunocompromised infants. In this study, we developed two real time PCR assays using TaqMan and SYBR Green to identify the pathogen after selective enrichment in mLST and BHI. The accuracy of two detections was tested by 35 strains of E. sakazakii and 88 non-E. sakazakii bacterial strains. The results showed that all of these E. sakazakii strains were positive reaction to the detections and all of the non-E. sakazakii strains were negative. The newly developed assays enable us to detect 1.1 CFU/100 g infant formula. And both of the assays can be accomplished within 2 business days. Compared to the traditional detection, the real time PCR procedures are quicker and simpler. In this study, we also developed a new method to design the primers, which can support multiple real time PCR with one pair of primers in SYBR Green detection. The detection methods are more sensitive and effective based on Two-Tm-Value of PCR. [Copyright &y& Elsevier]

Metallic phthalocyanines (MePcs) have shown their potential as catalysts for CO 2 reduction reactions (CO 2 RR). However, their low conductivity, easy agglomeration, and poor stability enslave the further progress of their CO 2 RR applications. Herein, an integrated heterogeneous molecular catalyst through anchoring CoPc molecules on 3D nitrogen-doped vertical graphene arrays (NVG) on carbon cloth (CC) is reported. The CoPc-NVG/CC electrodes exhibit superior performance for reducing CO 2 to CO with a Faradic efficiency of above 97.5% over a wide potential range (99% at an optimal potential), a very high turnover frequency of 35800 h -1 , and decent stability. It is revealed that NVG interacts with CoPc to form highly efficient channels for electron transfer from NVG to CoPc, facilitating the Co(II)/Co(I) redox of CO 2 reduction. The strong coupling effect between NVG and CoPc molecules not only endows CoPc with high intrinsic activity for CO 2 RR, but also enhances the stability of electrocatalysts under high potentials. This work paves an efficient approach for developing high-performance heterogeneous catalysts by using rationally designed 3D integrated graphene arrays to host molecular metallic phthalocyanines so as to ameliorate their electronic structures and engineer stable active sites., (© 2022 Wiley-VCH GmbH.)

Photothermal desalination is a promising approach for seawater purification by harvesting solar energy. Titanium carbide (Ti 3 C 2 T x MXene) membranes have been regarded as potential materials for photothermal desalination by virtue of their excellent light-to-heat conversion. However, achieving a well-balanced synergy between high evaporation rate and good salt resistance remains a significant challenge due to their limited solar absorption and inferior stability. Herein, we report a self-assembled flexible porphyrin-Ti 3 C 2 T x MXene Janus membrane (Janus PMX membrane) for dual-functional enabled photothermal desalination. The self-assembly of porphyrin on MXene not only effectively creates a favorable hydrophobic surface but also simultaneously enables efficient solar utilization. The significant interactions and charge redistribution between MXene and porphyrin lead to a stable hydrophobic/hydrophilic Janus structure with synergistically enhanced photothermal conversion. As a result, the Janus PMX membrane demonstrates highly efficient water pumping, heat localization, vapor generation, and salt resistance during photothermal desalination. This work presents an effective and facile strategy toward advancing a well-performing MXene membrane for efficient seawater desalination.

NaAlH 4 has been widely regarded as a potential hydrogen storage material due to its favorable thermodynamics and high energy density. The high activation energy barrier and high dehydrogenation temperature, however, significantly hinder its practical application. In this paper, CeO 2 hollow nanotubes (HNTs) prepared by a simple electrospinning technique are adopted as functional scaffolds to support NaAlH 4 nanoparticles (NPs) towards advanced hydrogen storage performance. The nanoconfined NaAlH 4 inside CeO 2 HNTs, synthesized via the infiltration of molten NaAlH 4 into the CeO 2 HNTs under high hydrogen pressure, exhibited significantly improved dehydrogenation properties compared with both bulk and ball-milled CeO 2 HNTs-catalyzed NaAlH 4 . The onset dehydrogenation temperature of the NaAlH 4 @CeO 2 composite was reduced to below 100 °C, with only one main dehydrogenation peak appearing at 130 °C, which is 120 °C and 50 °C lower than for its bulk counterpart and for the ball-milled CeO 2 HNTs-catalyzed NaAlH 4 , respectively. Moreover, ∼5.09 wt% hydrogen could be released within 30 min at 180 °C, while only 1.6 wt% hydrogen was desorbed from the ball-milled NaAlH 4 under the same conditions. This significant improvement is mainly attributed to the synergistic effects contributed by the CeO 2 HNTs, which could act as not only a structural scaffold to fabricate and confine the NaAlH 4 NPs, but also as an effective catalyst to enhance the hydrogen storage performance of NaAlH 4 .

Background: In a conventional P-median model, demanding points are likely assigned to the closest supplying facilities, but this method exhibits evident limitations in real cases., Methods: This paper proposed a modified P-median model in which exact and approximate strategies are used. The first strategy aims to enumerate all of the possible combinations of P facilities, and the second strategy adopts simulated annealing to allocate resources considering capacity constraint and spatial compactness constraint. These strategies allow us to choose optimal locations by applying visual analytics, which is rarely employed in location allocation planning., Results: This model is applied to a case study in Henan Province, China, where three optimal healthcare centers are selected from candidate cities. First, the weighting factor in spatial compactness constraint is visually evaluated to obtain a plausible spatial pattern. Second, three optimal healthcare centers, namely, Zhengzhou, Xinxiang, and Nanyang, are identified in a hybrid transportation network by performing visual analytics. Third, alternative healthcare centers are obtained in a road network and compared with the above solution to understand the impacts of transportation network types., Conclusions: The optimal healthcare centers are visually detected by employing an improved P-median model, which considers both geographic accessibility and service quality. The optimal solutions are obtained in two transportation networks, which suggest high-speed railways and highways play a significant role respectively.

Pathogen detection is critical to the process of generating and testing powdered infant formula (PIF). An obstacle associated with PIF microbial surveillance is that most current procedures are time-consuming and labor-intensive. We have developed a rapid, DNA microarray-based detection technique to identify 10 different pathogenic bacteria associated with PIF contamination based on the 16S-23S rRNA gene internal transcribed spacer (ITS) sequences and wzy (O antigen polymerase) gene. Using this procedure, Enterobacter sakazakii, Salmonella enterica, Klebsiella pneumoniae, Klebsiella oxytoca, Serratia marcescens, Acinetobacter baumannii, Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli O157 were identified. One hundred eighty-five strains were used to validate the microarray assay (including 134 target pathogen strains and 51 closely related bacteria). Twenty-seven probes reproducibly detected multiple pathogens with high specificity and sensitivity (0.100 ng genomic DNA or 10(4) CFU/ml). Twenty-one real PIF samples were tested by the microarray with 100% accuracy. The data presented reveal that the designed oligonucleotide microarray is a promising method for basic microbiology, clinical diagnosis, food safety, and epidemiological surveillance.

The 16S-23S rRNA gene internal transcribed spacer (ITS) regions of Klebsiella spp., including Klebsiella pneumoniae subsp. pneumoniae, Klebsiella pneumoniae subsp. ozaenae, Klebsiella pneumoniae subsp. rhinoscleromatis, Klebsiella oxytoca, Klebsiella planticola, Klebsiella terrigena, and Klebsiella ornithinolytica, were characterized, and the feasibility of using ITS sequences to discriminate Klebsiella species and subspecies was explored. A total of 336 ITS sequences from 21 representative strains and 11 clinical isolates of Klebsiella were sequenced and analyzed. Three distinct ITS types-ITS(none) (without tRNA genes), ITS(glu) [with a tRNA(Glu (UUC)) gene], and ITS(ile+ala) [with tRNA(Ile (GAU)) and tRNA(Ala (UGC)) genes]-were detected in all species except for K. pneumoniae subsp. rhinoscleromatis, which has only ITS(glu) and ITS(ile+ala). The presence of ITS(none) in Enterobacteriaceae had never been reported before. Both the length and the sequence of each ITS type are highly conserved within the species, with identity levels from 0.961 to 1.000 for ITS(none), from 0.967 to 1.000 for ITS(glu), and from 0.968 to 1.000 for ITS(ile+ala). Interspecies sequence identities range from 0.775 to 0.989 for ITS(none), from 0.798 to 0.997 for ITS(glu), and from 0.712 to 0.985 for ITS(ile+ala). Regions with significant interspecies variations but low intraspecies polymorphisms were identified; these may be targeted in the design of probes for the identification of Klebsiella to the species level. Phylogenetic analysis based on ITS regions reveals the relationships among Klebsiella species similarly to that based on 16S rRNA genes.