Since its first fabrication by exfoliation in 2014, phosphorene has been the focus of rapidly expanding research activities. The number of phosphorene publications has been increasing at a rate exceeding that of other two-dimensional materials. This tremendous level of excitement arises from the unique properties of phosphorene, including its puckered layer structure. With its widely tunable band gap, strong in-plane anisotropy, and high carrier mobility, phosphorene is at the center of numerous fundamental studies and applications spanning from electronic, optoelectronic, and spintronic devices to sensors, actuators, and thermoelectrics to energy conversion, and storage devices. Here, we review the most significant recent studies in the field of phosphorene research and technology. Our focus is on the synthesis and layer number determination, anisotropic properties, tuning of the band gap and related properties, strain engineering, and applications in electronics, thermoelectrics, and energy storage. The current needs and likely future research directions for phosphorene are also discussed. , there has been a quest for new two-dimensional (2D) materials aimed at fully exploring new fundamental phenomena stemming from quantum confinement and size effects. This quest has spurred new areas of research with rapid growth from both theoretical and experimental fronts aimed at technological advancements. Among recently discovered 2D materials, phosphorene is one of the most intriguing due to its exotic properties and numerous foreseeable applications.2 This review discusses recent advances in phosphorene research with special emphasis on: (i) fabrication and techniques for rapid identification of the number of layers; (ii) anisotropic behavior; (iii) band gap and property tuning; (iv) strain engineering and mechanical properties; (v) devices and applications; and (vi) future directions.2D materials composed of a single-atom-thick or a singlepolyhedral-thick layer can be grouped into diverse categories.

bla TEM-1 expression results in penicillin resistance, whereas expression of many bla TEM-1 descendants, called extended-spectrum ␤-lactamases (ESBLs), results simultaneously in resistance to penicillins and extendedspectrum cephalosporins. Despite the expanded resistance phenotypes conferred by many ESBLs, bla TEM-1 is still the most abundant bla TEM allele in many microbial populations. This study examines the fitness effects of the two amino acid substitutions, R164S and E240K, that have occurred repeatedly among ESBL bla TEM-1 descendants. Using a single-nucleotide polymorphism-specific real-time quantitative PCR method, we analyzed the fitness of strains expressing bla TEM-1 , bla TEM-10 , and bla TEM-12 . Our results show that bacteria expressing the ancestral bla TEM-1 allele have a fitness advantage over those expressing either bla TEM-10 or bla TEM-12 when exposed to ampicillin. This observation, combined with the fact that penicillins are the most prevalent antimicrobials prescribed worldwide, may explain why bla TEM-1 has persisted as the most frequently encountered bla TEM allele in bacterial populations.

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Accumulation of carnitine was studied in immortalized rat brain capillary endothelial cells RBE4, as an in vitro model of blood‐brain barrier. Both uptake and efflux phenomena were found independent on [Na+] gradient. A quick acylation of carnitine in RBE4 cells was observed, especially leading to formation of long‐chain acylcarnitines (46%), while 38% of the accumulated compound was found in the form of free carnitine. Exposure of basolateral membrane to carnitine‐free medium induced a quick efflux, leaving, however, about 50% of accumulated carnitine inside the cells. The process of accumulation was found to be sensitive to butyrobetaine and cysteine, but not to choline or Hemicholinium‐3, pointing to sterical demands of a transporter responsible for carnitine uptake.

SUMMARYAccumulation of carnitine was studied in immortalized rat brain capillary endothelial cells R B E~, as an in vitro model of blood-brain barrier. Both uptake and efflux phenomena were found independent on "a+] gradient. A quick acylation of carnitine in RBE4 cells was observed, especially leading to formation of long-chain acylcarnitines (46%), while 38% of the accumulated compound was found in the form of free carnitine. Exposure of basolateral membrane to carnitine-free medium induced a quick efflux, leaving, however, about 50% of accumulated carnitine inside the Cells. The Process of accumulation was found to be sensitive to butyrobetaine and cysteine, but not to choline or Hemicholinium-3, pointing to sterical demands of a transporter responsible for carnitine uptake.

We passaged cells expressing TEM-1 and TEM-12 from a single plasmid through either ampicillin or ceftazidime. We found that the combined effects of recombination and selection removed the bla TEM-1 allele from the bacterial population when it was passaged through ceftazidime or the bla TEM-12 allele when cultures were passaged through ampicillin.The overall abundance of bla TEM alleles in bacterial populations has caused multiple bla TEM alleles to coexist in single strains of bacteria (1, 4-7, 9-11, 15, 16), which has created the opportunity for recombination to occur among bla TEM alleles. The occurrence of recombination between two bla TEM alleles on a single plasmid strongly resembles gene conversion (14) and will cause the fragment between the recombination sites to be removed if the alleles are oriented in the same direction (3). This will typically result in the removal of one bla TEM allele from the plasmid while the remaining allele will usually be a chimera (Fig. 1). The potential for the removal of one bla TEM allele from a plasmid creates a situation in which closely related alleles may compete directly for retention in bacterial plasmids. While the bla TEM allele that is left on a plasmid following recombination is random, subsequent selection is not. Therefore, the combined effects of recombination and selection could result in the presence of a single allele on each copy of the plasmid and the removal of one of the alleles entirely from the population.To experimentally investigate whether allelic competition occurs in an environment with potential for both recombination and selection, we cloned the two bla TEM alleles bla TEM-1 and bla TEM-12 into the pAC3 vector (2) in the same orientation (Fig. 1A), validated the construction by sequencing, and expressed them from wild-type E. coli K-12. We passaged these bacteria through L broth containing either 32 g/ml ampicillin or 4 g/ml ceftazidime. Every 24 h, the saturated cultures were diluted 100 times in fresh broth, and the remaining bacteria were used to isolate plasmid for quantitative PCR (qPCR) analysis.Each 25-l qPCR reaction mixture contained 10 6 to 10 7 copies (60 pg of DNA) of the plasmid, 1ϫ Brilliant master mixture (Stratagene, La Jolla, CA), 200 nmol of each molecular beacon probe (Biosearch Technologies), and 900 nmol of each primer (Table 1). To measure the ratio between the origin of replication (Ori) and TEM alleles, recombination markers, and TET amplicons (Fig. 1), real-time PCR with TaqMan probes was performed. Each 25-l qPCR reaction mixture contained 10 6 to 10 7 copies of the plasmid DNA, 1ϫ Brilliant multiplex master mixture (Stratagene, La Jolla, CA), 200 nmol of each TaqMan probe (Biosearch Technologies), and appropriate concentrations of each primer (Table 1). The specificity of all primers and probes for the appropriate sequence was verified. Real-time PCR experiments were performed on a Stratagene Mx3000 multiplex qPCR system, with the quantitative PCR setting. The cycling conditions were either 1 cycle of 10 min at 95°C, ...

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