Despite the various synthesis methods to obtain carbon dots (CDs), the bottom‐up methods are still the most widely administrated route to afford large‐scale and low‐cost synthesis. However, as CDs are developed with increasing reports involved in producing many CDs, the structure and property features have changed enormously compared with the first generation of CDs, raising classification concerns. To this end, a new classification of CDs, named carbonized polymer dots (CPDs), is summarized according to the analysis of structure and property features. Here, CPDs are revealed as an emerging class of CDs with distinctive polymer/carbon hybrid structures and properties. Furthermore, deep insights into the effects of synthesis on the structure/property features of CDs are provided. Herein, the synthesis methods of CDs are also summarized in detail, and the effects of synthesis conditions of the bottom‐up methods in terms of the structures and properties of CPDs are discussed and analyzed comprehensively. Insights into formation process and nucleation mechanism of CPDs are also offered. Finally, a perspective of the future development of CDs is proposed with critical insights into facilitating their potential in various application fields.

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Hydrothermal/solvothermal treatments have been widely used to prepare carbonized polymer dots (CPDs) through the condensation and carbonization of small molecules and/or polymers. However, the basic scientific issues, such as the nucleation and growth process, morphology and size control, yield increase, and photoluminescence (PL) mechanism have not been well investigated. In this work, enlightened by the principle of soap-free emulsion polymerization, CPDs with ultrahigh yields (ca. 85 %) were obtained by hydrothermal addition polymerization and carbonization (HAPC) of monomers. The unprecedented initiator-induced addition polymerization was exploited to synthesize CPDs for the first time. As expected in typical emulsion polymerization processes, the developed HAPC method can produce CPDs with designed sizes by systematically regulating the HAPC parameter, uncovering an unprecedented strategy for regulating the size of CPDs. In addition, the obtained CPDs were provided with high photoluminescence quantum yields (PLQY) up to 45.58 %, while the relationship between the photoluminescence (PL) mechanism and chemical structure was investigated. The viscosity parameter was first adopted to measure the polymer property of CPDs. Moreover, the ultrahigh yield and low-cost CPDs elicited the high-performance CPDs/PVA nanocomposite (PVA=poly(vinyl alcohol)) with fluorescence and room-temperature phosphorescence dual-mode emission, demonstrating potential for advanced anti-counterfeit applications.

It is well known that plasmons in bulk metals cannot be excited by direct photoabsorption, that is, by coupling of volume plasmons to light. Here we demonstrate that the situation in nanoclusters of the same metals is entirely different. We have carried out a photodepletion measurement for Na(20) and Na(92) and identified a broad volume plasmon absorption peak centered slightly above 4 eV, revealing the possibility of optical excitation of volume-type collective electronic modes in a metallic system. The observed phenomenon is related to different selection rules for finite systems.

Recently, the room-temperature phosphorescence (RTP) properties of carbon dots (CDs) have attracted significant interest. However, the regulation of RTP emission faces great challenges because of untunable emissive lifetime and wavelength. Here, ultrahigh-yield acrylamide-based N-doped carbonized polymer dots (AN-CPDs) with ultralong RTP lifetime are synthesized by a one-step hydrothermal addition polymerization and carbonization strategy. The RTP lifetime and wavelength of the proposed AN-CPDs can be regulated by changing the carbonization degree. Thus, the AN-CPDs’ RTP lifetimes are in the range of 61.4–466.5 ms, while the RTP emission wavelengths vary from 485 to 558 nm. Further experiment and theoretical calculation proved that RTP can be attributed to the polymer/carbon hybrid structure and nitrous functional groups as the molecular state related emission centers. Supramolecular cross-linking in the aggregated state is vital for the RTP emission of the AN-CPDs by restricting the nonradiative transition of the triplet excitons. AN-CPDs of different RTP lifetimes can be applied to time-resolved multistage information encryption and multistage anticounterfeiting. This work facilitates the optical regulation and application potential of CDs and provides profound insights into the effect of the polymer/carbon hybrid structure on the properties of CDs.

The response of (H2O)(n=3-18) clusters to an electric field is studied by beam deflection. All clusters deflect uniformly, behaving as polarizable particles. The effective polarizabilities exceed the electronic component and increase as the clusters are cooled, revealing a large permanent dipole contribution. The results resolve a discrepancy concerning the polarity of water clusters and show that all species access conformations with moments exceeding 1 D. The data show no evidence for a freezing transition down to approximately 120 K, but suggest a shift in the conformer arrangement at n=8-9.

Streptococcus thermophilus strain ND03 is a Chinese commercial dairy starter used for the manufacture of yogurt. It was isolated from naturally fermented yak milk in Qinghai, China. We present here the complete genome sequence of ND03 and compare it to three other published genomes of Streptococcus thermophilus strains.Streptococcus thermophilus strain ND03 was isolated from naturally fermented yak milk in Qinghai, China (10). It has many excellent processing properties, such as flavor, acidity, viscosity, and water holding. This strain has been implemented in the industrial production of dairy starter cultures by Inner Mongolia Yili Industrial Group Company, Ltd., the largest dairy corporation in China.Whole-genome sequencing of S. thermophilus strain ND03 was performed with a combined strategy of 454 sequencing (9) and Solexa paired-end sequencing technology (1). Genomic libraries containing 3-kb inserts were constructed, and 124,126 paired-end reads and 28,120 singleend reads were generated using the GS FLX system, giving 20.5-fold coverage of the genome. The majority (93.5%) of reads were assembled into seven large scaffolds, including 86 nonredundant contigs, using the 454 Newbler assembler (454 Life Sciences, Branford, CT). A total of 5,647,930 reads (2.5-kb library) were generated to reach a depth of 163-fold coverage with an Illumina Solexa GA IIx (Illumina, San Diego, CA) and mapped to the scaffolds using BurrowsWheeler alignment (BWA) (7). The gaps between scaffolds were filled by sequencing PCR products using an ABI 3730 capillary sequencer. The genome analysis was performed as described previously (4, 5).The complete genome sequence of ND03 contains a circular 1,831,957-bp chromosome with a GC content of 39.1%. There are 2,038 genes in total, including 1,919 coding genes, five rRNA operons, and 56 tRNAs in the ND03 genome.Comparison of the LMG18311 (2), CNRZ1066 (2), LMD-9 (8), and ND03 genomes revealed that they were highly similar, with the exception of 73 encoding genes that are uniquely present in ND03 but not in the other three strains. Some of the unique genes formed six large insertion islands that were comprised by transposase, glutamate decarboxylase, acetyltransferase, glycosyltransferase, polysaccharide biosynthesis protein, and the exopolysaccharide (EPS) biosynthesis gene cluster.Similar to other dairy bacteria, S. thermophilus is able to synthesize EPSs that lead to an improvement in the viscosity and texture of yogurt (3). The ND03 genome carries a unique 23.4-kb EPS gene cluster (STND_1010 to STND_1035), which contains 10 EPS-related genes and six intact or truncated insertions (IS). Four of the EPS-related genes in the cluster, epsA, epsB, epsC, and epsD, were conserved between all four genomes in comparisons. These genes are involved in the regulation, polymerization, and chain length determination and export of the EPS. The remaining six genes (epsE, epsF, epsG, epsI, epsJ, and epsP) in the EPS gene cluster were uniquely present in ND03 and regarded as the key enzymes to determin...

Lactobacillus casei Zhang is a new probiotic bacterium isolated from koumiss collected in Inner Mongolia, China. Here, we report the main genome features of L. casei Zhang and the identification of several predicted proteins implicated in interactions with the host.