Mechanistic investigation of the influence of defects on armchair unburned carbon for PbCl2 adsorption.

As the largest consumer of coal energy, coal-fired power plants emit large amounts of PbCl2 each year, which is of wide concern due to its high toxicity, global migration, and accumulation. Unburned carbon is considered a promising adsorbent for effective PbCl2 removal. However, there is a problem that the current unburned carbon model cannot show the structure of carbon defects on the actual unburned carbon surface. Therefore, it is important to construct defective unburned carbon models with practical significance. In addition, the adsorption mechanism of PbCl2 by an unburned model is not studied deeply enough and the reaction mechanism is not clear yet. This has seriously affected the development of effective adsorbents. To reveal the adsorption mechanism of PbCl2 on unburned carbon, the adsorption mechanism of PbCl2 on defective unburned carbon surfaces was analyzed by using the density flooding theory to investigate the adsorption process of PbCl2 on different unburned carbon models. This will provide theoretical guidance for the design and development of adsorbents for the removal of PbCl2 from coal-fired power plants.

Ultrafast and Sensitive Self-Powered Photodetector Based on Graphene/Pentacene Single Crystal Heterostructure with Weak Light Detection Capacity.

Organic materials exhibit efficient light absorption and low-temperature, large-scale processability, and have stimulated enormous research efforts for next-generation optoelectronics. While, high-performance organic devices with fast speed and high responsivity still face intractable challenges, due to their intrinsic limitations including finite carrier mobility and high exciton binding energy. Here an ultrafast and highly sensitive broadband phototransistor is demonstrated by integrating high-quality pentacene single crystal with monolayer graphene. Encouragingly, the -3 dB bandwidth can reach up to 26 kHz, which is a record-speed for such sensitized organic phototransistors. Enormous absorption, long exciton diffusion length of pentacene crystal, and efficient interfacial charge transfer enable a high responsivity of >105  A W-1  and specific detectivity of >1011  Jones. Moreover, self-powered weak-light detection is realized using a simple asymmetric configuration, and the obvious zero-bias photoresponses can be displayed even under 750 nW cm-2  light intensity. Excellent response speed and photoresponsivity enable high-speed image sensor capability in UV-Vis ranges.  The results offer a practical strategy for constructing high-performance self-powered organic hybrid photodetectors, with strong applicability in wireless, weak-light detection, and video-frame-rate imaging applications.

Highly Sensitive and Ultrafast Organic Phototransistor Based on Rubrene Single Crystals.

Rubrene single crystals have received a lot of attention for their great potential in electronic and wearable nanoelectronics due to their high carrier mobility and excellent flexibility. While they exhibited remarkable electrical performances, their intrinsic potential as photon detectors has not been fully exploited. Here, we fabricate a sensitive and ultrafast organic phototransistor based on rubrene single crystals. The device covers the ultraviolet to visible range (275-532 nm), and the responsivity and detectivity can reach up to ∼4000 A W-1 and 1011 jones at 532 nm, respectively. Furthermore, the response times are highly gate-tunable down to sub-90 µs, and the cutoff frequency is ∼4 kHz, which is one of the fastest organic material-based phototransistors reported so far. Equally important is that the fabricated device exhibits stable light detection ability even after 8 months, indicating great long-term stability and excellent environmental robustness. The results suggest that the high-quality rubrene single crystal may be a promising material for future flexible optoelectronics with its intrinsic mechanical flexibility.

Details of the topological state transition induced by gradually increased disorder in photonic Chern insulators.

Using two well-defined empirical parameters, we numerically investigate the details of the disorder-induced topological state transition (TST) in photonic Chern insulators composed of two-dimensional magnetic photonic crystals (MPCs). The TST undergoes a gradual process, accompanied with some interesting phenomena as the disorder of rod positions in MPCs increases gradually. This kind of TST is determined by the competition among the topologically protected edge state, disorder-induced wave localizations and bulk states in the system. More interestingly, the disorder-induced wave localizations almost have no influence on the one-way propagation of the original photonic topological states (PTSs), and the unidirectional nature of the PTSs at the edge area can survive even when the bulk states arise at stronger disorders. Our results provide detailed demonstrations for the deep understanding of fundamental physics underlying topology and disorder and are also of practical significance in device fabrication with PTSs.

Obestatin and cardiovascular health.

Obestatin, encoded by the same gene as ghrelin, was first described as a physiological opponent of ghrelin through an interaction with the orphan receptor GPR39. However, the effects of obestatin were not totally contrary to the effects of ghrelin in cardiovascular regulations based on the recent studies. We summarize here the current evidences surrounding the cardiovascular actions of obestatin, and the possible implications of obestatin as a therapeutic agent in common conditions such as hypertension and heart failure.

Recognizing nucleosides with transverse electronic transport via perpendicular direction of base planes for DNA sequencing.

Putting the four DNA nucleosides in the middle of gold [111] nanoelectrodes with base planes parallel to the electrode surface layer, we study the transverse electronic transport properties of four nucleosides along the direction of electrodes. First, the optimal distance of the electrodes is released. The results show that the optimal electrode distance to study transverse electronic transport characteristics of DNA nucleosides is about 0.68 nm. Second, we theoretically calculate the conductance and current of the four nucleosides via perpendicular direction of base planes in the bias range of [-2, 2] V by exploiting the first principle theory. According to the calculated results, we propose three methods to recognize the nucleoside type in practice application.

High-resolution separation of graphene oxide by capillary electrophoresis.

Separation and purification of graphene oxide (GO) prepared from chemical oxidation of flake graphite and ultrasonication by capillary electrophoresis (CE) was demonstrated. CE showed the ability to provide high-resolution separations of GO fractionations with baseline separation. The GO fractionations after CE were collected for Raman spectroscopy, atomic force microscopy, and transmission electron microscopy characterizations. GO nanoparticles (unexfoliated GO) or stacked GO sheets migrated toward the anode, while the thin-layer GO sheets migrated toward the cathode. Therefore, CE has to be performed twice with a reversed electric field to achieve a full separation of GO. This separation method was suggested to be based on the surface charge of the GO sheets, and a separation model was proposed. This study might be valuable for fabrication of GO or graphene micro- or nanodevices with controlled thickness.

Controlled synthesis of Pt nanoparticles array through electroreduction of cisplatin bound at nucleobases terminated surface and application into H2O2 sensing.

Fabrication of sub-monolayer array of Pt nanoparticles (PtNPs) assembled at nucleobases terminated layers and their application into H(2)O(2) and glucose sensing were reported. To prepare such a PtNPs assembly, 3-mercaptopropionic acid (MPA), Zr(4+), nucleotide-5'-monophosphate (NTMP including guanosine, adenosine, cytidine, uridine-5'-monophosphate, and abbreviations were GMP, AMP, CMP, UMP, respectively) were adsorbed onto Au substrate sequentially to form nucleobases terminated surface and Zr(4+) acted as binder to link carboxylic and phosphoric groups (NTMP/Zr(4+)/MPA/Au). Complexation of cisplatin, cis-Pt(NH(3))(2)Cl(2), with terminated nucleobases and following electrochemical reduction of surface-bound cisplatin gave PtNPs attached surface. Different PtNPs coverage or particle density was obtained depending on the NTMP used and decreased in the order: PtNPs/GMP/Zr(4+)/MPA/Au>PtNPs/AMP/Zr(4+)/MPA/Au>PtNPs/CMP/Zr(4+)/MPA/Au>PtNPs/UMP/Zr(4+)/MPA/Au. The surface loading of Pt was between 160 and 16 ng/cm(2). The as prepared PtNPs can be used as electrocatalysts for H(2)O(2) sensing (detection limit of H(2)O(2)<100 nM) and the sensitivity increased with decreasing PtNPs density. After adsorption of glucose oxidase, the modified electrode can be used as enzymatic electrode for glucose sensing and a detection limit of 38.5 µM was achieved. This study provided an example of fabricating PtNP arrays utilising surface complexation of cisplatin with nucleobases. The advantage of this method is that the NP density can be controlled through changing nucleobases or Pt complexes used to obtain suitable kinetics of the complexation reactions. Additionally, the PtNPs sub-monolayer as prepared has high sensitivity for H(2)O(2) sensing even at a very low loading of Pt.

Effects of Metal Ions on Conductivity and Structure of Single DNA Molecule in Different Environmental Conditions.

We design a novel nano-gap electrode to measure the current of DNA molecule, by which the current-voltage characteristics of individual native DNA, Ag-DNA and Ni-DNA molecules are obtained, respectively. The results show that the voltage gap of Ag- and Ni-DNA is higher than that of native DNA, and the conductance is lower than native DNA in neutral environment. The structure transition from B- to Z-DNA is observed in the presence of high concentrations of nickel ions and Ag-DNA appears chaos state by STM image and U-V spectra characterization. But in alkaline environment, the conductance of Ni-DNA rises and the voltage gap decreases with the increasing of nickel ion concentration denotes that the conductive ability of Ni-DNA is higher than that of native DNA.

[Preparation of DNA silver nanowire and its Raman spectra].

Silver nanoparticles were synthesized by the method of combining heating with UV irradiation. In the authors' work, the shape and size of nanograins which carry positive electrical charges are uniform and their average diameter is 7.8 nm. Based on the electrostatic self-assembly characteristics of DNA, silver nanoparticles were equally assembled on predefined aligned calf thymus DNA to form DNA silver nanowires. The diameter of the wires is about 30 nm and the length is 2 microm. The Raman spectra indicate that the silver nanoparticles mainly attach to the backbone chain of DNA and affect the vibration properties of deoxyribose and base. The intensity of the peaks at 782 and 1 098 cm(-1) assigned to stretch vibration of phosphoric skeleton decreases sharply and the band at 782 cm(-1) shifts to 791 cm(-1). The bands of deoxyribose C-O stretch vibration at 1 011 and 1 050 cm(-1) shift to 1 030 and 1 064 cm(-1) respectively. The characteristic peaks of bases at 1 372, 1 334, 1 304 and 728 cm(-1) shift to 1 368, 1 320, 1 294 and 731 cm(-1), respectively.

Study on the Electric Conductivity of Ag-Doped DNA in Transverse Direction.

In this article, we reported a novel experiment results on Ag-doped DNA conductor in transverse direction. I-V characteristics were measured and the relative conductances were calculated for different silver ions concentrations. With the increase of the concentration of silver ions, the conductive ability of DNA risen rapidly, the relative conductance of DNA enhanced about three magnitudes and reached a stable value when Ag(+) concentration was up to 0.005 mM. In addition, Raman spectra were carried out to analyse and confirm conduction mechanism.

Raman spectra of single cell from gastrointestinal cancer patients.

AIM: To explore the difference between cancer cells and normal cells, we investigated the Raman spectra of single cells from gastrointestinal cancer patients. METHODS: All samples were obtained from 30 diagnosed as gastrointestinal cancer patients. The flesh tumor specimen is located in the center of tumor tissue, while the normal ones were 5 cm away from the outside tumor section. The imprint was put under the micros-cope and a single cell was chosen for Raman measurement. All spectra were collected at confocal Raman micro-spectroscopy (British Renishaw) with NIR 780 nm laser. RESULTS: We measured the Raman spectra of several cells from gastrointestinal cancer patients. The result shows that there exists the strong line at 1 002 /cm with less half-width assigned to the phenylalanine in several cells. The Raman lines of white cell were lower and less, while those of red cell were not only higher in intensity and more abundant, but also had a particular C-N breathing stretching band of pyrrole ring at 1 620-1 540 /cm. The line at 1 084 /cm assigned to phosphate backbone of DNA became obviously weaker in cancer cell. The Raman spectra of stomach cancer cells were similar to those of normal cells, but the Raman intensity of cancer cells was much lower than that of normal cells, and even some lines disappear. The lines of enteric cancer cells became weaker than spectra above and many lines disappeared, and the cancer cells in different position had different fluorescence intensity. CONCLUSION: The Raman spectra of several cells from cancer patients show that the structural changes of cancer cells happen and many bonds rupture so that the biological function of cells are lost. The results indicate that Raman spectra can offer the experiment basis for the cancer diagnosis and treatment.

[Raman spectra of cell from breast cancer patients].

Raman spectra of normal and cancer cell from breast cancer patients a represented. It is reported that all of the Ramanlines become weak. The intensities of Raman lines 782 and 1 084 cm(-1) of DNA phosphate group and 1 155 and 1 262 cm(-1) of deoxyribosephosphate decrease. The spectral lines 812 cm(-1) of A-type DNA and 979 and 668 cm(-1) disappear, and the 905 cm(-1) peak is shifted to lower frequency by 6 cm(-1). This means that the phosphate backbone of DNA is destroyed to a certain extent and the fissiparity of cancer cell can't be controlled effectively. In addition, the authors found a kind of Raman line 960 cm(-1) concerning calcificationand sclerosis of cancer cell. The results indicate that Raman spectra may offer the experiment basis for the cancer diagnosis and treatment.

Temperature-dependent Raman spectra of collagen and DNA.

Raman spectra of collagen and DNA were discussed at different temperatures. The temperature-dependence of Raman intensity was obtained in the region from -150 to 200 degrees C. Four denaturation points at 0, 40, 68 and 90 degrees C of collagen and two peaks at 38 and 82 degrees C for DNA were obtained. The wavenumbers of many vibrational modes were found to increase for lower temperature, but the peak at 1302 cm(-1) of collagen and the peak at 1101 cm(-1) of DNA showed the opposite trend. In all of the vibrational modes of DNA, the bases showed the most sensitive to different temperatures and there is a pronounced shift of bands at 70 degrees C, the starting point of denaturation.

[Resonance Raman spectra of single red-cell from human blood].

Resonance Raman spectra of single red-cell from human blood are presented by different laser sources. It is reported that there is 1002 cm(-1) line of insensitive conformation of phenylalanine aromatic ring stretching and 1620 cm(-1) line of C-N breathing stretching band of pyrrole ring, which cause strong and sharp resonance lines when excited by 782 nm laser source. They are weaker and the intensity of other lines of high wave number is large and clear when excited by 514 nm laser source. But the intensity of lines of low wave number is strong and clear when excited by 782 nm laser source. At the same time, the authors got Raman spectra lines at different times after taking blood under the same laser source. When using 782 nm laser source, there is no difference except for 1601 cm(-1). There are a lot of weakened lines and lines shifting about 4-10 cm(-1) toward low wave number. The results indicate that Raman spectra may offer the experimental basis for studying structure, function and variability of single red-cell.

[Temperature dependence of collagen by Raman spectra].

Raman spectra of collagen I at different temperature were obtained. There was no change at 1003 cm(-1) line, 1302 cm(-1) line moved to a higher wave number, but other lines moved to lower wave number when temperature increased. In addition, the authors observed the temperature dependence of Raman intensity and four denaturation points at 0, 40, 68 and 90 degrees C respectively. The points at 40 and 68 degrees C are in agreement with the experimental data by DSC and SHG. The point at 0 degrees C might be frozen transition; the point at 90 degrees C might be related to the damage of secondary structure. When heated to 150 degrees C, the Raman intensity of all bands decreased rapidly and many lines disappeared.