Photoreactive olefinic species are incorporated into am etal-organic framework (MOF), [Zn(bdc)(3-F-spy)] (1). Single crystals of 1 are shown to undergo three types of photomechanical macroscopic deformation upon illumination by UV light. To demonstrate the practical potential of this system, the inclusion of 1 in aP VA (polyvinyl alcohol) composite membrane,b ye xploiting hydrogen-bonding interactions,i sp resented. Using this composite membrane,t he amplification of mechanical stress to achieve macroscopic actuation behavior is demonstrated. These results pave the way for the generation of MOF-based soft photoactuators that produce clearly defined mechanical responses upon irradiation with light. Such systems are anticipated to have considerable potential in photomechanical energy harvesting and conversion systems.Actuation materials that effectively convert external controllable stimuli into mechanical energy have recently attracted attention in the fields of soft robotics, [1] biomedicine, [2] biomimetic systems, [3] and molecular machines, [4] with synthetic materials having the potential to undergo intended deformations involving twisting,b ending,s wimming,a nd elongation/contraction. [5] Va rious types of smart actuation driven by external physical or chemical stimuli (for example, heat, [6] electricity, [7] magnetism, [8] humidity, [9] or light [10] )have been extensively investigated and developed. Thedesign and fabrication of as mart actuation that can achieve multiple desired deformations and perform target functions are essential prerequisites. [4,11] Accordingly,t he manipulation and deformation of actuation associated with rapid and precise response is of great relevance to both fundamental research and practical applications toward the prompt and Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.
The factors driving the composition of gut microbiota are still only partly understood but appear to include environmental, cultural, and genetic factors. In order to obtain more insight into the relative importance of these factors, we analyzed the microbiome composition in subjects of Tibetan or Han descent living at different altitudes. DNA was isolated from stool samples. Using polymerase chain reaction methodology, the 16S rRNA V1–V3 regions were amplified and the sequence information was analyzed by principal coordinates analysis and Lefse analyses. Contrasting the Tibetan and Han populations both living at the 3600 m altitude, we found that the Tibetan microbiome is characterized by a relative abundance of Prevotella whereas the Han stool was enriched in Bacteroides. Comparing the microbiome of Han stool obtained from populations living at different altitudes revealed a more energy efficient flora in samples from those living at higher altitude relative to their lower-altitude counterparts. Comparison of the stool microbiome of Tibetan herders living at 4800 m to rural Tibetans living at 3600 m altitude shows that the former have a flora enriched in butyrate-producing bacteria, possibly in response to the harsher environment that these herders face. Thus, the study shows that both altitude and genetic/cultural background have a significant influence on microbiome composition, and it represents the first attempt to compare stool microbiota of Tibetan and Han populations in relation to altitude.
Bactrian camels serve as an important means of transportation in the cold desert regions of China and Mongolia. Here we present a 2.01 Gb draft genome sequence from both a wild and a domestic bactrian camel. We estimate the camel genome to be 2.38 Gb, containing 20,821 protein-coding genes. Our phylogenomics analysis reveals that camels shared common ancestors with other even-toed ungulates about 55–60 million years ago. Rapidly evolving genes in the camel lineage are significantly enriched in metabolic pathways, and these changes may underlie the insulin resistance typically observed in these animals. We estimate the genome-wide heterozygosity rates in both wild and domestic camels to be 1.0 × 10−3. However, genomic regions with significantly lower heterozygosity are found in the domestic camel, and olfactory receptors are enriched in these regions. Our comparative genomics analyses may also shed light on the genetic basis of the camel's remarkable salt tolerance and unusual immune system.
Developing epidermal electronics for physiological signal monitoring, including human biopotential (electroencephalogram [EEG], [1,2] electrocardiogram [ECG], [3-6] and electromyogram [EMG] [7-9]) and vibration (pulsation [10,11] and voice [12,13]) signals, is of great importance for next-generation wearable medicine, human-computer interaction, and smart robot applications. In general, most reported flexible electronics exploit plastic or elastic matrices (PET, PI, PDMS, Ecoflex, parylene, etc.) with
One coordination polymer [Zn2(L)2(bpe)2(H2O)2] (1) (L = 4,4'-((1,2-phenylenebis(methylene))bis(oxy))dibenzoic acid; bpe = (E)-1,2-di(pyridin-4-yl)ethene) was prepared and structurally determined. Compound 1 has a chain structure in which its pair of bpe ligands is arranged in a head-to-tail manner with their C=C bonds being close enough for a [2 + 2] cycloaddition reaction. Upon exposure to UV light, compound 1 undergoes a single-crystal-to-single-crystal (SCSC) [2 + 2] photodimerization to generate one 2D coordination polymer [Zn(L)(rctt-tpcb)0.5(H2O)] (1a) (rctt (regio cis, trans, trans)-tpcb = tetrakis(4-pyridyl)cyclobutane). The tpcb ligands in the crystals of 1a show an intriguing in situ thermal isomerisation. The nanospheres of 1 can be obtained by recrystallization in DMSO/alcohol. The nanospheres of 1a can also be readily produced from the corresponding nanospheres of 1 by the photocyclodimerization method. Compared with those of 1a, the nanospheres of 1 display highly selective sensing of Fe(3+) ions over mixed metal ions through fluorescence quenching. Moreover, the nanospheres of 1a can rapidly adsorb CR (congo red), MB (methylene blue) or RhB (rhodamine B) over MO (methyl orange) from aqueous solutions. This work offers a new photoinduced post-synthetic method for the synthesis of multifunctional MOFs, which show luminescence sensing of Fe(3+) ions and dye adsorption properties.
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