Yersinia pestis, forms an enveloping hydrogel whose role is to inhibit interactions with host cells.E. coli, offer a new family of tissue culture materials.Regenerative medicine demands the recreation of complex cell–cell and cell–matrix interactions observed in vivoYersinia pestis, the etiologic agent of the bubonic plague, produces a unique form of CU polymer. After being injected into a warm blooded host via a flea bite,caf1 gene to produce a thick polymeric CU hydrogel coating on the surface of the cell. This efficiently resists cell interactions and, by acting as a kind of anti‐adhesin, inhibits macrophage attacks.4Gram‐negative bacteria often form protein polymers on their surfaces via the chaperone‐usher (CU) pathway,Y. pestis Caf1 protein has been described by a series of elegant papers from Knight and co‐workers who solved the high resolution structures of the chaperone (Caf1M‐Caf1) and also revealed the energetics of the polymer formation.−1. Furthermore the polymers are stable up to 90 °C,14The formation of the FigureModels of Caf1 structureTo imitate fibronectin, we inserted into Caf1 the Arg‐Gly‐Asp‐Ser peptide (RGDS) which has been shown to confer cell adhesion properties similar to the whole fibronectin molecule.caf1, from its own temperature dependent promoter, was revealed by the presence of a flocculent layer (FL) above the cell pellet (CP) after centrifugationThe expression of Of the five mutants, L2RGDS (Loop 2 insertion) did not express Caf1, L5RGDS had the highest yield and thus we constructed a loop 5 Caf1 RGES mutant (L5RGES) as a non‐cell‐adhesive control12Next, to assess Caf1's suitability for cell culture, cell viability was assayed via calcein uptake. When cultured on surfaces coated with Caf1‐RGDS, Caf1‐RGES and Caf1‐WT neither 3T3 fibroblasts nor PC12 cell lines revealed any toxicity within 48 h . However, 3T3 cells proliferated more on fibronectin. Fibronectin is a large protein which contains several other important peptides for cell proliferation such as PHSRN, LDVP and IDAP and so the challenge is to incorporate several different motifs in Caf1 fibers as shown later.FiguresWe then studied cell morphology and adhesion in detail using scanning electron microscopy (SEM). Each cell line was grown on 12 mm glass cover slips pre‐coated with either Caf1WT, L5RGDS, L5RGES, Fibronectin or Collagen IV, incubated for 24 h, fixed and visualized by SEM Figures. Thus CaFigurecaf1 gene which included a FLAG epitope termed caf1‐FLAG. The expression of caf1 encoded by pAH34L is temperature sensitive whilst the expression levels of caf1‐FLAG encoded by pBAD33 can be modulated over a varied range of L‐arabinose concentrations. Analysis of co‐expression of Caf1 mutants was performed by western blot. Since the pBAD33 plasmid carries neither chaperone nor usher protein genes the caf1‐FLAG did not form polymers by itself , NHS‐PEG‐NHS (197 Å), and 4‐arm NHS‐PEG (2 × 197 Å). These can react with any of the eight surface lysines on each Caf1 monomer. The Caf1 hydrogels were characterized using a simple tube‐inversion assay in which non–cross linked solutions would flow down the sides of the plastic reaction vessel. The gelation time was visually estimated  to be within 24 to 27 min for NHS‐PEG‐NHS and 2 to 22 min for 4‐arm PEG‐NHS, depending on the concentration of the cross‐linker. The higher the concentration of these two cross‐linkers the quicker the gelation time. With DTSSP a solid gel was not observed. The increase in gelation rate of 4‐arm PEG‐NHS could be due to the structure of 4‐arm PEG which influences its ability to react with the primary amine groups of Caf1.The Caf1 polymer can also be used to form a hydrogel with possible applications in 3D cell culture. WTCaf1 at a final concentration of 30 mg mLAfter cross‐linking for 30 min, samples were analyzed on a 4–20% gradient gel. The band of approximately 15 kDa corresponding to the Caf1 monomer in the non‐cross linked Caf1 sample (control) was used as a reference for the subsequent analysis. The relative density of the unreacted Caf1 monomer band, in Caf1 samples cross‐linked with the different cross‐linkers at various concentrations, was determined. Since the calculations of the relative density for the high molecular weight bands were more complex, these were considered a single band and referred to as the “Caf1 cross‐linked fraction”. The 4‐arm PEG‐NHS showed the least amount of residual monomer and thus a higher degree of cross linking Caf1 polymers cross‐linked with a short arm length cross‐linker such as DTSSP (12.0 Å) promote a closer contact between the Caf1 fibres. Thus, the images obtained by TEM revealed a compact Caf1 hydrogel which reflects the Caf1 fibres proximity. A different result was obtained for Caf1 polymers cross‐linked with a long spacer NHS‐PEG‐NHS (197 Å), which can better separate the Caf1 fibres. Large Caf1 hydrogel meshes were observed by TEM. When we used the 4‐arm PEG‐NHS where each cross section is also 197 Å the interactions between Caf1 and the 4‐arm PEG‐NHS the structure was more condensed than that produced by NHS‐PEG‐NHS .When using a monomeric form of Caf1 made by circular permutation, cpCaf1,The pore diameters of 4‐arm PEG‐NHS stabilized Caf1 hydrogels were assessed by SEM and ESEM .As shown by Lutolf and Hubbell (2005)For details of the experimental methods used please see the Supporting Information.As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re‐organized for online delivery, but are not copy‐edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors.SupplementaryClick here for additional data file.


Since at this size the surface contribution to the volume becomes predominant, it turns out that the material becomes significantly resistant against particles coarsening with temperature, entailing a significant delay in the anatase to rutile phase transition, prolonging up to 1000 °C in air. A noticeable alteration of the phase stability diagram with lithium insertion is also experienced. Lithium insertion in such nanocrystalline anatase TiO2 converts into a complete solid solution until almost Li1TiO2, a composition at which the tetragonal to orthorhombic transition takes place without the formation of the emblematic and unwished rock salt Li1TiO2 phase. Consequently, excellent reversibility in the electrochemical process is experienced in the whole portion of lithium content.This work sheds light on the exceptional robustness of anatase TiO It is the leading contender material for photocatalysis182 structures, among which 6 are stable under ambient conditions and 5 are high pressure phases. The thermodynamically most stable structure under ambient conditions is the rutile followed by the brookite and the anatase202 towards nano has led to surprising discoveries. One of those regards the size dependency of the phase stability diagram. This was highlighted by Banfield et al. who concluded a size crossover threshold of 14 nm below which the anatase TiO2 becomes in reality the most stable polymorphet al. using calorimetric solid/air surface energy measurements and solution calorimetry, concluding a crossover when the BET surface area becomes greater than 50 m2.g−1, corresponding to a size of 30 nm assuming spherical particles. This crossover in the relative polymorphism stability stems from the five times lower surface enthalpy of the anatase which modifies significantly the total free Gibbs energy of the system when reducing the size232 when going towards the nano2 basically undergoes one first order phase transition at ca. 1.75 V (vs. Li+/Li) involving the coexistence in the grain of an anatase lithium-poor LiαTiO2 phase  and a lithium-rich orthorhombic phase LiβTiO2 26271TiO2 composition, can be reached solely if the particle size is sufficiently reduced. It occurs below 1.5 V through a second biphasic reaction separating the orthorhombic LiβTiO2 and Li1TiO2 for which the structure corresponds to a tetragonal lattice cell similar to the anatase with ca. 3.5% lattice volume expansion26et al.αTiO2 on the one hand and LiβTiO2 on the other hand when the particles are ranging in the nanoscale domain. This phenomenon is driven by a thermodynamic effect resulting from a more favorable minimization of the free enthalpy of the system when the phases are separating rather than the coexistence of two phases in one grain. A similar process has been revealed in other nanocrystalline biphasic materials such as LiFePO4/FePO4 and Li4Ti5O12/Li7Ti5O1231+ when going from 140 to 7 nm TiO22O34TiOca. 4 nm, is reached (SBET ≈ 300 m2.g−1). This translates into an abnormally high temperature for anatase to rutile transformation. We are also exposing a complete vanishing of the miscibility gap upon lithium insertion which transforms the galvanostatic curve from a classic potential/composition plateau into a S-shape profile along the full range of lithium composition, without ending up to the formation of the rock-salt LiTiO2. The relevance of this new feature on the electrochemical performances of the particles and the fundamental and practical outcomes of such findings is herein discussed.In the present study, we reveal the exceptional robustness of the anatase crystal structure when an extremely small particle size, of ca. 80 m2.g−1)372.g−1 (±1 m2.g−1) by analysis of the nitrogen adsorption part using a 6 points method (CBET = 80). Analysis of the desorption part using the Barrett-Joyner-Halenda (B.J.H.) method is reported in hkl = 0.35 nm). This direction corresponds to the low energy facet of the anatase TiO2414F(aq) medium (pH ≈ 6). The XPS spectrum of the Ti 2p core peak is showing, as expected for TiO2, a strict Ti4+ valence state profile with the 2p3/2 and 2p1/2 components at 458.9 eV and 464.6 eV, respectively  ascribed to the (110), (101), (200), (111), (210) (…) reflections of the rutile polymorph. The rutile grows at the expense of the anatase structure. The two phases are coexisting between 630 °C to 790 °C before turning completely into rutile under our experimental conditions. By comparison, the thermal stability of the 4 nm is drastically changed. No phase transition is noticed even at temperatures of as high as 850 °C. Note that this temperature threshold corresponds to the upper limit of the furnace used for this in situ x-ray diffraction study. Whereas the experimental procedure was rigorously the same, such a difference clearly highlights the main implication of the particle size in the thermal stability of the anatase. Nevertheless, a slight contribution of the low amount adsorbed fluoride upon the anatase TiO2 surface cannot be rule out since this latter is reported to also stabilize the energy surface of the anatase; consequently to contribute in the delaying of the anatase-to-rutile transition temperature to a range of 800 °C to 900 °C in air45articles  with thearticles . For thein situ Raman spectroscopy showing that in fact anatase to rutile transition takes place at a temperature of as high as 1000 °C in the 4 nm particles -catalysis for instance in which the anatase polymorph is well-established to exhibit higher catalytic activity than the rutile polymorphA very similar experiment was performed by articles . Rutile ca. 550 °C for the 20 nm particles versus ca. 700 °C for the smaller particles. Interestingly the shape of the exponential also differs; the rise being steeper in the case of the bigger particles. The greater robustness of anatase crystal structure against temperature is ascribed to the deferred process of particles coalescence and grain coarsening. This comes in good agreement with the literature which has hypothesized grain coarsening to be the main factor directing the transition to rutile as a result from the stepwise decrease of surface energy contribution to the total free Gibbs energyThe evolution of crystallite size as a function of temperature for the two samples was calculated by using Williamson-Hall formalism. The evolution is gathered in in situ XRD experiment, we evaluated that the transition towards rutile starts when the crystallite size attains a value of around 32 nm. Interestingly, such value is never reached regardless of the temperature in the case of the 4 nm particles. Anatase is completely transformed to rutile when the sizes of the crystallites reach around 60 nm. These values obtained by in situ x-ray method also corroborate relatively well the set of numbers reported by Banfield et al. based on another approach relying on the expression of the surface energies from monitoring isothermal coarsening kinetics of nano-sized TiO2Based on this 2/TiO2 contacts remain theoretically unchanged and a new solid/solid interface appears between TiO2 and the conducting carbon (KetjenBlack 600). Also note that no binder was used in the electrode formulation to avoid any additional components. 2 of 20 nm and the 4 nm using an intermediate cycling rate of C/20 (ie. one lithium inserted/de-inserted every 20 hours). For the preparation of the composite electrodes, the active material is manually mixed with Ketjen Black 600-type carbon (denoted as KB600) in a mortar . It results in the destruction of the original needles leading to individual spherical nanoparticles well dispersed within the electron percolating carbon network. The lithium insertion/deinsertion process into/from the 20 nm particles features a distinct potential-composition plateau at ca. 1.75 V (vs. Li+/Li) involving the insertion of 0.58 lithium cation at a cutoff potential of 1.5 V (vs. Li+/Li). This plateau corresponds to the well-established bi-phasic reaction separating the quadratic lithium-poor LiαTiO2 phase (S.G. I41/amd) and the orthorhombic lithium-rich LiβTiO2 phase (S.G. Imma). The values of α and β are a function of the particle sizeca. 0.11 and ca. 0.50, respectively. However, when decreasing further the size to 4 nm, there is a drastic modification in the shape and capacity of the galvanostatic discharge/charge curve which is then characterized by a monotonous potential decrease/increase of potential during lithium insertion/deinsertion process. This S-shape galvanostatic curve is typically credited to a solid solution in which the lithium is inserted without long range ordering into the octahedral interstitial sites. Last but not least, this solid solution-like curve also comes with an enhancement in the electrochemical capacity of the material since this latter can host 0.67 Li+ per formula unit at a cutoff potential of 1.5 V (vs. Li+/Li), compared to 0.58 Li+ for the 20 nm sample. Such a difference translates into a gain in gravimetric capacity of around 30 mAh.g−1. ICP-AES determination of the lithium content on the smallest size TiO2 was giving 0.65 lithium-ion per formula unit in excellent agreement with the Coulomb law.The exceptional stability of the anatase crystal structure at extreme nano size is also verified by electrochemical means in a remarkable manner. In this case, the interface becomes different compared to the previous section. Previously, the high robustness of the anatase crystal structure was derived from the low solid/gas surface energy. In the case of a conventional lithium-ion battery configuration, the interfaces become more complex. The predominant one corresponds to a solid/liquid (electrolyte) interface, TiOin situ/in operando x-ray diffraction study and by selected area electron diffraction study. The galvanostatic intermittent titration technique (G.I.T.T.) reported in in situ x-ray diffraction study between TiO2 and Li0.5TiO2 even though the diffraction peaks are relatively broad owing to the nanosize character of the particles. The results are self-consistent with a complete solid solution domain as witnessed by the continuous shift of the (101) diffraction plane towards lower diffraction angles during lithium insertion and the absence of the orthorhombic LiβTiO2 phase appearing at the expense of the quadratic LiαTiO2 . This capacity is slightly greater than the theoretical capacity of TiO2 (337 mAh.g−1) and the experimental capacities on anatase nanorods et al.+  suggests this extra-capacity to arise in part or in whole from an early electrolyte degradation at low potential leading to the formation of a solid electrolyte interphase (SEI) in good agreement with recent observations made on iron-doped TiO2 nanoparticles synthesized by a very close procedure et al.+ . This exrocedure 53.1TiO2. Indeed, for x = 0.9 Li+, the resulting SAED pattern is still indexed with the anatase crystal structure by contrast to the composition of x = 1.1 Li+ for which the diffraction pattern does not match anymore. Along this remarkable extension of the solid solution domain, only the positions of the rings are modified as a result from lattice cell volume evolution during the lithium ion intake. The refinement of the ring position for the different crystal orientations shows upon insertion that both a and c parameters are increasing (2 (Vcell = 132.0 Å3) and the anatase Li0.9TiO2 (Vcell = 159.7 Å3). Such an uncommon value of cell expansion without evident particles fracturing denotes the excellent flexibility of the anatase framework at the nanometric scale. For lithium composition beyond 0.9 Li+, the quadratic symmetry is broken and the SAED patterns can be indexed solely with the orthorhombic LiβTiO2 phase (S.G. Imma). This phase transition is likely driven by stress relaxation since the cell volume shrinks considerably to a more common value of 140.7 Å3. The β value in the literature ranges between 0.5 to 0.7 Li+ 1TiO2 solved first by Cava et al. becomes less stable at nanoscale than the orthorhombic counterpart1TiO2 was always avoided in practice owing to its poor electrical properties. Therefore lithium insertion into the anatase TiO2 was always restricted to the formation of LiβTiO2. Because of the miscibility gap loss, we managed to cycle in the full range of lithium composition. This corresponds to a noticeable gain in capacity of ca. 65 mAh.g−1 and almost 130 mAh.g−1 in comparison to a conventional anatase TiO2 with a value of β of around 0.5 Li+. Nevertheless, although the capacity at potentials lower than 1 V is increasing with the particle decrease, likely due to SEI formation, the elimination of the rocksalt Li1TiO2 structure at nanosize does not pave the way towards the possibility of proceeding in the lithium conversion reaction of the anatase TiO2 yielding to Ti0 embedded in Li2O-based matrix.The selected area electron diffraction patterns for the different lithiated samples provide more local information on the lithiation procedure at nanoscale. The results, gathered in creasing . A disti1TiO2 is transformed at extreme nanosize into a complete solid solution domain until almost the full lithium occupation into the anatase. The kinetically restricted rock-salt structure is no longer stable at nanosize, at which it is replaced by an orthorhombic Li1TiO2 similar to the previously reported Li0.5TiO2. As a result, an excellent reversibility in the electrochemical processes can be obtained without any electrode formulation optimization in the whole portion of the solid solution domain (until x = 0.9 Li+). Nonetheless the development of an optimized electrode formulation will be required to fully take advantage of this complete solution domain with the aim to fully exploit the theoretical capacity of the anatase TiO2.In this work, we established the high robustness of the anatase crystal structure when going to extreme nano-sizing as a result from the very low energy surface of the anatase which, when the surface prevails to the total volume, affects the established phase stability diagram whether it is solid/air interface and solid/electrolyte interface in a lithium-ion battery. This translates into a delayed process of grain coarsening causing a significantly higher temperature required to onset the anatase to rutile transition. The mechanism of lithium insertion is also strongly modified. The two characteristically reported two-phase insertion processes yielding to the quadratic rock-salt Li4 (titanium (IV) isopropoxide) was added to 300 mL of water under vigorous stirring for 4 hours to ensure complete hydrolysis. The white precipitate was then retrieved by vacuum filtration or centrifugation, washed several times with water followed by ethanol and dried at room temperature overnight. It was then divided into several batches and kept for ageing from several days to 3 months at room temperature (20 °C) in a solution of NH4F(aq) of 0.1 mol.L−1 −1 of titanium isopropoxide (29.3 g) was mixed with an equimolar proportion of acetic acid (6 g) under stirring. The solution was kept under vigorous stirring for 15 min and transferred into 175 mL water for titanium hydrolysis. The solution was kept for 1 hour. 1 mL of nitric acid is then added and the solution peptized at 78 °C for 90 minutes (ramp of 45 min). The solution turns from white to light blue. The solution was then concentrated with a rotavap (50 °C/60 mBar) until 60 g is obtained. The resulting solution is autoclaved at 250 °C for 12 hours in a Parr Teflon vessel (Volume 100 mL)The synthesis of the 4 nm particles was performed as follows: 30 mL Ti(iOPr)2 samples were retrieved from the battery in an Ar-filled glove box, carefully washed with DMC and recovered by centrifugation inside the glove box. The sample was transferred into the microscope column without any air exposure.Titanium isopropoxide and ammonium fluoride were purchased from Aldrich and used as received. Transmission Electron Microscopy (TEM) and Selected Area Electron Diffraction were performed using a high resolution FEG FEI Tecnai F20 S-TWIN with accelerating tension of 200 kV. The simulations of SAED patterns were carried out using Electron Diffraction Software. Lithiated TiOIn situ x-ray diffraction patterns were acquired using a Be-based electrochemical cell suited to a Bruker D8 diffractometer . In situ x-ray diffraction with temperature was performed on a Bruker D8 diffractometer with a Co radiation  equipped with an Anton Parr Chamber HTK from room temperature to 850 °C. Each pattern was recorded in air with a heating rate of 0.08 °C.s−1. Raman measurements were performed using the 514.5 nm line from an argon ion laser and analyzed using a Jobin Yvon T64000 spectrometer equipped with a charge coupled device. An optical microscope was used to focus the incident light as a spot of about 2 μm in diameter on the sample. The temperature dependence of the Raman spectra was measured using a TS1500 Linkam stage from room-temperature to 1100 °C with a heating rate of 10 °C.min−1. XPS measurements were carried out with a Kratos Axis Ultra spectrometer, using a focused monochromatized Al Kα radiation (hυ = 1486.6 eV). The XPS spectrometer was directly connected through a transfer chamber to an argon dry box, in order to avoid moisture/air exposure of the samples. For the Ag 3d5/2 line, the full width at half maximum (FWHM) was 0.58 eV under the recording conditions. The analysed area of the samples was 300 × 700 μm2. Peaks were recorded with a constant pass energy of 20 eV, and 160 eV for the survey spectra. The pressure in the analysis chamber was around 5.10−9 mbar. Short acquisition time spectra were recorded before and after each normal experiment to check that the samples did not suffer from degradation during the measurements. The binding energy scale was calibrated from the hydrocarbon contamination using the C1s peak at 285.0 eV. Core peaks were analysed using a nonlinear Shirley-type background6 in 1:1 EC/DMC). Galvanostatic experiments were performed using a VMP3 galvanostat/potentiostat. For Galvanostatic Intermittent Titration Technique experiments (GITT), the cells were intermittently discharged/charged for 30 minutes at C/20 rate with open circuit voltage periods of 50 hours.All electrochemical tests were performed in two-electrode Swagelok-type cells. For this, the active material was mixed in a mortar with 15% in mass of KB600. The electrochemical cell consisted of around 10 mg of active material separated from a lithium foil by two fiberglass sheets soaked by a LP30 Merck electrolyte .


Hepatocyte nuclear factor-1beta (HNF1β) was initially identified as a liver-specific transcription factor. It is a homeobox transcription factor that functions as a homodimer or heterodimer with HNF1α. HNF1β plays an important role in organogenesis during embryonic stage, especially of the liver, kidney, and pancreas. Mutations in the HNF1β gene cause maturity-onset diabetes of the young type 5 (MODY5), renal cysts, genital malformations, and pancreas atrophy. Recently, it has been shown that the expression of HNF1β is associated with cancer risk in several tumors, including hepatocellular carcinoma, pancreatic carcinoma, renal cancer, ovarian cancer, endometrial cancer, and prostate cancer. HNF1β also regulates the expression of genes associated with stem/progenitor cells, which indicates that HNF1β may play an important role in stem cell regulation. In this review, we discuss some of the current developments about HNF1β and tumor, the relationship between HNF1β and stem/progenitor cells, and the potential pathogenesis of HNF1β in various tumors. Hepatocyte nuclear factors (HNFs) are a group of transcription factors that play important roles in regulating transcription of the liver specific genes. HNFs are expressed predominately in the liver and form a complicated network regulating liver development and hepatocyte differentiation. However, these transcription factors are not restricted to hepatocytes, they are also expressed in many other tissues. Nevertheless, the liver is the only tissue in which a significant number of different HNFs are expressed at the same time . Four maThe HNF1β gene (TCF2) is located on chromosome 17q12 . The firHNF1β has been demonstrated to be associated with the risk of hepatocellular carcinoma (HCC). The HNF1 family plays a dominant role in liver-specific transcription. Hepatocyte differentiation is linked to the expression of liver-specific proteins and that the expression patterns are controlled primarily at their transcription levels. It is suggested that HNF1α and HNF1β may play distinct roles in regulating gene expression in differentiation and maturity of hepatocytes. Studies showed that cultured cells derived from differentiated hepatoma cells express HNF1α, whereas cultured dedifferentiated hepatoma cells express HNF1β instead of HNF1α. Analysis of the expression of HNF1α and HNF1β mRNA HCC tissues by RT-PCR assay showed that the ratio of HNF1α/HNF1β mRNA is closely linked to histological differentiation of HCC . The ratHNF1β is expressed in biliary precursor cells and plays a crucial role in extrahepatic biliary development . BiliaryPancreatic carcinoma is the fourth most common cause of death among cancers. In pancreas, HNF1β is a useful marker to identify clear cell carcinomas, and its overexpression may predict worse survival. Kim et al.  found thColorectal cancer (CRC) is the third and fourth most common cancer in females and males. Studies have indicated that the accumulation of genetic and epigenetic alterations could result in the transformation of normal colonic epithelial cells to adenocarcinomas . SILVA eSeveral studies suggest a role of HNF1β in tumor formation and various kinds of renal disease. Renal cell carcinoma (RCC) accounts for more than 80 % of kidney tumors. Studies found that HNF1β expression was reduced in tumor tissue compared with normal kidney tissue. HNF1β is essential for the maintenance of well-ordered renal tissue growth, and downregulation or loss of expression is correlated with malignant transformation and dedifferentiation. HNF1β is a prognostic factor and a potential tumor suppressor, and could be a potential therapeutic target for RCC . ChromopProstate cancer is one of the most common male malignancies. Recently, a large study has shown that an HNF1β sequence variant confers an increased prostate cancer risk. The first report of HNF1β associated with prostate cancer risk was in a genome-wide association study (GWAS) searching for sequence variants in 1501 Icelandic men with prostate cancer and 11,290 controls, and the variant, rs4430796, in HNF1β at chromosome 17q12 was the earliest loci to be discovered for prostate cancer , 25. TheHNF1β was identified from large-scale gene expression studies as being a useful marker of ovarian and uterine clear cell carcinomas. Clear cell carcinoma (CCC) of the ovary has the worst prognosis of all of the epithelial ovarian cancers. A study has demonstrated that the expression of HNF1β is significantly upregulated in ovarian CCC cell lines, while non-CCC ovarian cancer cell lines rarely express this protein, also, reduction of HNF1β induced apoptotic cell death in ovarian CCC cell lines . HNF1β wEndometrial cancer is the most common gynecological cancer in developed countries. A genome-wide association study identified single nucleotide polymorphisms in HNF1β associated with endometrial cancer risk in women of European background . SNP rs4The aberrant expression of HNF1β in tumors is associated with epigenetic processes and epigenetic changes. In humans, one of the epigenetic mechanisms that regulate expression of genes is methylation of the clusters of CpG dinucleotides, called CpG islands. A probable mechanism of aberrant up-regulation of HNF1β in ovarian clear cell carcinoma is hypomethylation of the HNF1β CpG island . TerasawThe pathway with which HNF1β is involved in cancer is less understood. HNF1β has been identified as one of the most highly overexpressed genes in ovarian CCC. In ovarian CCC cell lines, one of the most markedly up-regulated genes was osteopontin (OPN), which is probably a direct target gene of HNF1β, since OPN contains functional HNF1β binding sites in the promoter region . It was + cells in human pancreatic cancer Bxpc-3 and Panc-1 cells have the properties of cancer stem cells, with strong tumourigenic ability [HNF1β has been described as a key regulator of biliary development and is partially regulated by Notch signaling . The Not ability . Gene ex ability . Moreove ability .Genes and pathways regulating stem and progenitor cells are increasingly recognized in tumorigenesis. Tumors may often originate from the transformation of normal stem cells, since similar signalling pathways may regulate self-renewal in stem cells and cancer cells. According to the cancer stem cell (CSC) hypothesis, a few CSC with self-renewal and multipotentiality differentiation exist in tumors, and these cells can create heterogeneity in a tumor through abnormal proliferation and differentiation. In HEK293 cells and ovary CCC, HNF1β activates the CD24 gene, a cell surface protein that has recently been identified as a marker of the renal progenitor population in the uninduced metanephric mesenchyme . CD24 isIn liver development, HNF1β is involved in the hepatobiliary specification of hepatoblasts to cholangiocytes, and it is strongly expressed throughout the embryonic and adult biliary epithelium. Immunostaining of patients with advanced alcoholic liver disease showed that ductular reaction cells were positive for HNF1β, whereas HNF1β was not expressed in mature hepatocytes . It is dHNF1β plays an important role in tumorigenesis of various organs. High expression of HNF1β showed worse survival in both pancreatic carcinoma and hepatocelullar carcinoma. HNF1β expression is reduced in renal cell carcinoma compared with normal kidney tissue. HNF1β may functions as a tumor suppressor gene in renal cell carcinoma. In prostate cancer, the studies of HNF1β focus mainly on the single nucleotide polymorphisms. Genome-wide association studies have discovered at least 30 susceptibility loci for prostate cancer. It is demonstrated that HNF1β would be an excellent marker for distinguishing CCCs from other lesions in both the ovary and the endometrium. In ovarian cancer, downregulation of HNF1β may contribute to drug resistance, thus estoration of HNF1β function could be a therapeutic approach. Many genetic and epigenetic alterations of HNF1β gene as well as several genetic networks and signaling pathways that are considered to be involved in the development and progression of tumor. The details of the regulatory pathways and their mechanisms are still under investigation. Studies also showed that HNF1β is closely associated with stem/progenitor cells. However, the potential pathogenic mechanisms of HNF1β in cancer and regulatory mechanisms in stem cells are still less understood. Thus, further study for HNF1β with tumor and stem cell is still needed.


The past two years have witnessed unprecedentedly rapid development of organic–inorganic halide perovskite–based solar cells. The solution–processability and high efficiency make this technology extraordinarily attractive. The intensive investigations have accumulated rich experiences in the perovskite fabrication; while the mechanism of the chemical synthesis still remains unresolved. Here, we set up the chemical equation of the synthesis and elucidate the reactions from both thermodynamic and kinetic perspectives. Our study shows that gaseous products thermodynamically favour the reaction, while the activation energy and “collision” probability synergistically determine the reaction rate. These understandings enable us to finely tune the crystal size for high-quality perovskite film, leading to a record fill factor among similar device structures in the literature. This investigation provides a general strategy to explore the mechanism of perovskite synthesis and benefits the fabrication of high–efficiency perovskite photoactive layer. The recent exploitation of organic–inorganic hybrid perovskite in solar energy conversion arouses new academic curiosity1358AMX3, where A is methylamine, M is metal element and X represents halide element1112132 (M = Pb or Sn) and CH3NH3X (X = Br or I) with a molar ratio of 1:3. The preparation of CH3NH3PbIx3-Clx film through reaction (1) is a typical example2  and CH3NH3X (X = Br or I) with a molar ratio of 1:1, such as the reaction between PbI2 and CH3NH3I for the synthesis of CH3NH3PbI3 (reaction 2)Typically, the perovskite adopts a chemical formula denoted by The reported high–efficiency devices are mostly based on these two reactions163NH3PbIx3−Clx, a precursor solution containing PbCl2 and CH3NH3I with a molar ratio of 1:3 in dimethylformamide (DMF) was prepared (donated as “PbCl2 + 3CH3NH3I system”). The mixed solution was then spin–coated on TiO2 compact layer on an FTO–coated glass. The formation of final perovskite film was achieved by annealing at 100 oC for 45 min. X-ray diffraction (XRD) pattern shows typical (110) and (220) peaks centered at 14.1o and 28.4o  of CH3NH3Cl in the film accounts for negligible chlorine left in the final perovskite193, CH3NH2 or neutral CH3Cl, etc. To obtain a definite answer, we managed to separately collect the acidic or basic gases by filtering through acidic or basic media. Fourier transform infrared spectroscopy (FTIR) is used to characterize the vibrational modes of the collected gases in a gas cell. When the gas product was purged through NaOH powder, the spectrum  and 2 peaks cespectrum  shows pe145 cm−1 . To confin 2 min . It is aCH3NH3Cl . HoweverCH3NH3Cl  and lite10) and 2 peaks ceoC. The rationality behind this experiment is that HCl and CH3NH2 generated from the precursor film are able to enter into the upper pre-formed perovskite film and react with it. As a consequence, the surface of the perovskite film was observed to turn back to yellow. Furthermore, annealing of the yellow sample can again lead to the formation of the perovskite, indicating that the reaction between PbCl2 and CH3NH3I is reversible. In this case, the reaction depicted by (1) can be more precisely described by equation (3):Because of the generation of gaseous products, we also observed that if the reaction was conducted at a reduced pressure, the reaction would speed up because of the fast removal of the gaseous products. This is a typical characteristic of the solid-state reaction involving gaseous product generation. On the other hand, the reaction rate is greatly decreased when the reaction was performed in an enclosed system where the generated gas is retained in the system, indicating that the escape of gaseous product is a driving force for the reaction. To examine the reversibility of the reaction, we place a perovskite film facing a precursor film. The bottom precursor film was then heated up to 100 3NH2 favours the entropy increase and high temperature promotes the forward reaction.Since ΔG = ΔH − T ·ΔS , the reduction of Gibbs free energy induced by the entropy increase becomes increasingly significant as the temperature increases. Apparently, the release of HCl and CHin situ XRD to probe the crystal structure evolution–associated intermediate chemical reactions. The precursor film was firstly pre-dried at 60 oC. XRD measurement displays several sets of diffraction patterns .To explore the reaction pathways, we apply patterns . First, o and 31.37o can be assigned to the diffractions of CH3NH3PbCl3,2 and CH3NH3Cl has also happened along with the ion exchange as in reaction (5). There is also XRD diffraction peak at 14.02o corresponding to CH3NH3PbI3 observed at this stage, indicating the reaction (6).Second, the peaks at 15.53o, 16.64o, 28.42o and 18.03o cannot be assigned to any perovskite or lead halide; these peaks are presumably associated with the complex intermediate phase that composed of Pb halide and the organic species (Pb-complex)The diffractions at 11.38oC, the typical XRD diffraction pattern , (200), (210) and (300) plane with a cubic structure2 and CH3NH3PbCl3, accompanied by the growth of the diffraction peaks of CH3NH3PbI3  and (8) as indicated in o, 16.64o, and 18.03o gradually disappears as a result of the consumption of Pb for the formation of perovskite at elevated temperature (Another notable observation from the XRD pattern is that the (100) and (200) diffraction peaks downshift continuously during the annealing at 100 oC , which cperature .Ea) of the reaction. To obtain Ea, we first of all explore a parameter that can quantify the reaction rate. Considering the nature of the solid-state reaction, the gas release speed is associated with the reaction rate. If we assume that the overall reaction is described by reaction (9) below, a complete transformation to the perovskite leads to a weight loss of 17.9% as the gaseous products escape. This complete transformation to a pure-iodide based perovskite is reasonable since prolonged heating often results in undetectable chlorine content, both observed in our investigations and in the literatureThe kinetic factor that influences the reaction rate is usually reflected by the activation energy  of reaction (9), the precursor solution was pre-dried at 80  mixture . Subseques 15.2% , which iRr) against time (t) to determine the order of the reaction. The constant reaction rate as a function of time (Rr = k (k is the rate constant of the forward reaction). The natural logarithm form of Arrhenius equation can be expressed by formula (10).We thus plot the reaction rate  −1/T plot , (5) and (6) are nearly instantaneously occurred after drying at 60 oC. The calculated Ea represents required energy for the conversion of Pb-complex, CH3NH3PbCl3 (reaction d), CH3NH3PbI3−xClx (reaction e), to CH3NH3PbI3.where 1/T plot  we can c3NH3PbI3 displays zero-order reaction characteristics.Since the conversion towards final all-iodide perovskite is reversible and involves gaseous products generation, the increase in reactant would increase the distance for the gases diffusion out of the film. Furthermore, the increased diffusion length would increase the back reaction. An overall result is that the reaction rate did not show increment along with the increase of reactant amount. This is the reason why the formation of CH2 and CH3NH3I as the precursors, the reaction between PbI2 and CH3NH3I is conducted in a 1:1 ratio to generate CH3NH3PbI3 without chlorine doping (denoted as “PbI2 + CH3NH3I system”). The electronic properties of the two kinds of perovskites and their film formability are quite different2622 and CH3NH3I at 60 oC, the yielded light yellow powder was heated at elevated temperature to facilitate the reaction. The weight loss of the reaction was found to be 10.2% (Different from the perovskite synthesis using PbClbe 10.2% . From thRr (at constant temperature of 110 oC) against t to determine the order of the reaction  – 1/T plot (2 + 3CH3NH3I system (69 kJ mol−1). For the analysis of Ea, we characterized the dried mixtures of the two systems. It was found that the “PbCl2 + 3CH3NH3I” system forms poor crystallized product while the “PbI2 + CH3NH3I” system forms better crystallized material according the XRD characterization , the PCE can reach 12.26%, with a short-circuit current density (Jsc) of 19.66 mA cm−2, an open-circuit voltage (Voc) of 1.00 V, and a fill factor (FF) of 0.62. The average PCEs and standard deviations based on over twenty devices of each set are summarized in 2 and CH3NH3I as the precursors (device 2) leads to a PCE of 4.29%, with Jsc of 13.14 mA cm−2, Voc of 0.82 V and FF of 0.40. When using the mixture of lead precursors with CH3NH3I:PbCl2:PbI2 of 1.5:0.25:0.75 (device 3), 2.0:0.5:0.5 (device 4) and 2.5:0.75:0.25 (device 5), the PCEs are 13.78%, 15.00% and 13.05%, respectively. In the device fabrication, we found that to maintain 1:3 ratio between PbCl2 and CH3NH3I and 1:1 ratio between PbI2 and CH3NH3I in the precursor is crucial for the high–quality photoactive films.The photocurrent density-voltage responses of the devices  and the 3, 4, 5) with films prepared by using mixed PbCl2 and PbI2 sources are larger than that of the two devices fabricated using only PbCl2 or PbI2 as the lead precursor. The FF for the optimal device reaches 0.72 (device 4). FF is a parameter that reflects the quality of the device and is associated with the total resistance of the devices. The FFs of the devices based on the planar heterojunction , 1:0:1 , 1.5:0.25:0.75 (device 3), 2:0.5:0.5 (device 4) and 2.5:0.75:0.25 (device 5). The total concentration of lead salt in each solution was kept at 0.88 M.All materials were purchased from commercial suppliers and used as received unless stated otherwise. CH−1 was washed by sonication with deionized water, ethanol and acetone and then treated with oxygen plasma for two minutes. A compact layer of TiO2 was deposited on the FTO substrate by spin-coating the titanium precursor (0.24 M titanium isopropoxide and 0.12 M HCl in ethanol) at 5000 r.p.m. for 60 s following by calcination on a hotplate at 500 oC for 40 min. Subsequently, the perovskite solution was spin-coated on the cooled TiO2/FTO substrate in a nitrogen-filled glovebox at 3000 r.p.m. for 60 s. It was annealed on a hotplate at 100 oC for the reaction and crystallization of the perovskite. The optimized annealing time for the above-mentioned five precursors is 45 min, 10 min, 15 min, 23 min and 33 min, respectively. Then, the HTM, spiro-OMeTAD, was deposited by spin coating a solution  and 26.3 μL lithium-bis(trifluoromethanesulfonyl)imide (Li-TSFI) stock solution (520 mg mL-1 in acetonitrile) in 1 mL chlorobenzene) at 5000 r.p.m. for 60 s. After oxidizing the HTM layer in air for 15 h, the cell was completed by thermally evaporating a 100 nm-thick silver layer.FTO-coated glass with sheet resistance of 14 Ω sq−1. 25 μL perovksite solution containing CH3NH3I and PbCl2 of a molar concentration of 2.64 M and 0.88 M (mass percentage 42%) was held at 80 oC in a ceramic crucible for 150 min until the weight kept unchanged. A weight loss of 56% meant that DMF nearly totally evaporated. Then the remaining solid was heated from 80 oC to 180 oC at a rate of 5 oC min−1 during which CH3NH3PbIx3-Clx formed in the reaction  solution was held at 60 oC until the solvent DMF was totally evaporated. Mass loss of 60% meant that one DMF molecule is possibly binding with one Pb atom in the remaining solid. Then the yielded light yellow solid was heated from 60 oC to 110 oC and held at 110 oC till the complete reaction , the readily spin-coated perovskite film on TiO2/FTO substrate was transferred from a glovebox into an XRD characterization cell which was filled with nitrogen. The temperature of the characterization cell was held at 60 oC at first and then increased to 100 oC and kept for 50 min until the complete formation of CH3NH3PbI3. During this annealing stage, in situ XRD characterization  was performed from 10 degree to 50 degree (2θ) at a speed of 5 degree/min at a condition of 40 kV and 80 mA. The characterization process was repeated every ten minutes to monitor the phase change during the annealing stage.For the −1 from 10 degree to 70 degree (2θ)  .−1. Two probes mounted on the micropositioners were put in touch with the FTO and the silver electrodes, respectively. A scanning voltage from −0.2 V to 1.2 V was applied across the two electrodes at a step of 0.05 V and the corresponding current was recorded. All the cells had an active area of 0.12 cm2 defined by the silver electrode.The J-V characterization of the solar cells was conducted in a nitrogen-filled glovebox under the luminescence of AM 1.5 G solar-simulated light with an intensity of 100 mW cmThe incident photon current efficiency (IPCE) of the cells was characterized in air under the luminescence of monochromatic light from 300 nm to 800 nm in a DC mode without bias light. The output current of the cell was record at each wavelength. With the incident light powder known, the conversion efficiency from incident photons to the output charges was thus calculated for the whole spectrum.Rr) of the PbCl2 + 3CH3NH3I system was derived by taking a derivative on the weight of the reactant as a function of time at an isothermal temperature of 150 oC. The calculated reaction rate was 0.004 mg min−1 and gradually decreased to 0.003 mg min−1 after 150 min which could be considered as constant. It should be noted that the amount of the reactant is significantly larger than that in the device fabrication, so the required time for completing the reaction becomes much longer. On the other hand, with the generation of product in a solid-state reaction, the diffusion time of reactants becomes longer and longer, the apparent reaction rate thus becomes slower and slower.The reaction rate  – 1/T plot (k represents the reaction rate constant and T is thermodynamic temperature). Since the reaction between CH3NH3I and PbCl2 is a zero order one, then we can write A is the pre-exponential factor and R is the universal gas constant) based on Arrhenius equation. The reaction rate was calculated within a temperature range from 120 oC to 150 oC. For the reaction of the PbI2 + CH3NH3I system, we can write that W respresents the weight of the reactant since this is a first-order reaction. The data for plotting ln(k) – 1/T is in the temperature range between 70 oC and 100 oC.The activation energy of the above two reaction systems was calculated from the fitted slope of ln.


These compounds’ apparent chemical simplicity has made their prebiotic availability assumed, however, although the kinetic behavior and thermochemical properties of TAA and analogous esters have been preliminarily explored in other contexts, the geochemical relevance of these compounds merits further evaluation. Therefore, the chemical behavior of the simplest thiolated acetic acid derivatives, TAA and methylthioacetate (MTA) were explored here. Using laboratory measurements, literature data, and thermochemical models, we examine the plausibility of the accumulation of these compounds in various geological settings. Due to the high free energy change of their hydrolysis and corresponding low equilibrium constants, it is unlikely that these species could have accumulated abiotically to any significant extant.Thioesters and thioacetic acid (TAA) have been invoked as key reagents for the origin of life as activated forms of acetate analogous to acetyl-CoA. These species could have served as high-energy group-transfer reagents and allowed carbon insertions to form higher molecular weight compounds such as pyruvate. The apparent antiquity of the Wood-Ljungdahl CO The abiotic chemistry of thioesters and their possible occurrence in natural HT environments is then discussed in the context of prebiotic chemistry.2S·9 H2O (98%), NaHS·x H2O, MTA and TAA  were purchased from Sigma-Aldrich and used without further purification. D2O (99.9%) was purchased from Wako. Water (18.2 MΩ at 25 °C) was obtained from a Milli-Q Integral 3 Water Purification system.Acetic acid (99.99%), sodium methanethiolate (95%), Na2O/D2O to give a final concentration of 0.36 M or 0.036 M before the solution was placed into an NMR tube under air. A 0.1 M sodium carbonate buffer was used for pH 10 reactions and a 0.1 M sodium phosphate buffer was used for pH 7 reactions. 0.1 M phosphoric acid was used to adjust the pH of reactions conducted at pH 2.5. The natural pH of a 0.36 M aqueous TAA solution was measured as 2.5, increasing to ~3.8 after complete hydrolysis.In a typical experiment, TAA or MTA were mixed with 4:1 H1H NMR experiments were conducted in 5 mm outer diameter borosilicate and constricted NMR tubes (Norell Standard series) using a Bruker Avance III spectrometer. Temperature was held constant during measurements within +/−0.1 °C using a variable temperature unit. The pH of the reactions was monitored by placing aliquots of the reaction mixtures on Sigma-Aldrich Hydrion Brilliant disposable pH sticks, which are accurate to +/−0.1 pH unit. pH was further measured using a Mettler Toledo HM-25R pH meter. Reported pH values were not adjusted for the presence of D2O, which may introduce an inaccuracy of up to ~0.4 pH units at 25 °CNMR analysis was begun within 10 minutes of preparing the mixtures. −1 were omitted from energy calculations for consistency with the harmonic approximation used for calculation of thermochemical propertiesDensity Functional Theory (DFT) calculations were performed using the Jaguar 8.9 software package purchased from Schroedinger, Inc.3COOH or AcOH) and H2S or CH3SH , 64.2 ± 19.9 kJ mol−1 (pH 7) and 62.9 ± 22.7 kJ mol−1 (pH 10) for TAA. For comparison, Cefola et al.−1 between 70 and 90 °C at pH 12.5. Our measured values for MTA between 30 and 100 °C at pH 2.5, 7 and 10 are 62.8 ± 3.2 kJ mol−1, 42.3 ± 14.9 kJ mol−1 and 101.2 ± 16.4 kJ mol−1, respectively.Acetic acid was the only observable product of TAA degradation by 2S and CH3SH are pH-dependent. At 25 °C the pKa of acetic acid is 4.75, those of H2S are ~7 and >19 ± 2, and that of CH3SH ~10.43328The speciation of acetic acid, Ha of the sulfhydryl group of TAA is 3.7, rendering it less electrophilic above this pH value, and because S2− is a poor leaving group. Under the alkaline (~pH 10), cooler (~40 °C) conditions often favored for origin of life models for off-axis serpentinizing environments, TAA has a half-life of a few years, while that of MTA is a few hours.TAA is relatively unstable under acidic conditions, while MTA is least stable in base, which is explicable by the fact that the pKIt is worth noting that the dielectric constant of water drops by ~20–30% between the lowest and highest temperature points explored here for each compound and set of pH valuesDFT calculations at the B3LYP/6-31G* level were used to obtain Gibbs energies of formation for aqueous TAA, MTA, and their hydrolysis products. These values were then used to calculate the ΔG of hydrolysis for each species between 0 and 300 °C. The change in protonation state of the reactants and products with changing pH was also considered. The results of these calculations are shown in −1 −1 −1 −1 for TAA at 0 °C and pH 2.5 gives an equilibrium constant for TAA synthesis from acetic acid and H2S of ~1.3 × 10−10, strongly favoring hydrolysis. At higher temperatures the equilibrium constant is somewhat higher: at 300 °C it is ~7.3 × 10−6  at can be no larger than ~2.8 × 10−10 M−1 hr−1, and were it that high, it would not have been detectable during the time course of our experiments.where kThe linearity of the Arrhenius plots presented in Modern submarine HT systems are diverse, displaying extreme variability in the composition of their effluent depending on their host mineralogies and hydrodynamics, which have been studied extensively  can be significant in high temperature fluids, these are precipitated rapidly upon cooling due to the formation of metal sulfides2Sulfide concentrations in vent fluids are likely governed by concentrations of soluble metal species such as Ni and Fe, among others2 systems, which may contain large amounts of CH4, may inherently limit the production of higher hydrocarbons due to equilibria such as those obtained in Equation 3With regard to the propensity of HT vent chemistry to produce organics beyond the simple hydrocarbons which may be produced in trace amounts in such systems−1 eq values of ~1.2 × 1012, 4.4 × 109 and 4.0 × 107 at 25, 100 and 200 °C, respectively.The estimated ΔrG′° for this reaction is −68.9 ± 14.2 kJ mol2/reduced Fe systems are limited in their ability to supply H2 or reduced C 3)2+ to serve as a reducing agent, even though high concentrations of C species might allow for escape from the kinetic limitations of forming higher C-species.Likewise, high COIf the upper mantle had already largely reached its modern oxidation state by 4.35 Ga, as appears to be true from recent measurements of rare earth elements in zircons1255Nevertheless, high- and low-end estimates for the concentrations of some species can be broadly constrained. Sulfide concentrations in the bulk Archaen ocean (~4-2.5 Ga) have been suggested to have been in the low mM rangeunderestimated in any environment.For the sake of subsequent calculations, we will assume a generous 20 mM sulfide concentration for vent fluid or the bulk ocean, acknowledging that this value may be overestimated by orders of magnitude depending on the exact geochemical setting under consideration. Due to metal sulfide solubility product constraints, these values are unlikely to be 2S concentrations, MTA concentrations similarly by CH3SH concentrations. Except under strongly acidic conditions, TAA is generally more stable than MTA, but TAA is undoubtedly more plausible simply due to the likely much higher abundance of H2S, which is more abundant than CH3SH in modern HT vent fluids by a factor of 1000 or more  and mineral or other types of catalysis (which in principle would only speed the time to equilibration), nevertheless the equilibria cannot be high due to the factors discussed above.Given the second order rate and yield dependencies of condensation reactions, which typically decline inversely as a function of reactant concentrations, these concentrations are very low for the sake of performing more complex organic chemistry in HT environments. In our study, even examining the behavior of TAA or MTA concentrated far beyond what is plausible in natural marine environments, we note that only the predicted hydrolysis products are observed by NMR.3SH (8 mM) in the presence of 350 mM CO. This is ~500 times and ~3700 times the highest CH3SH and CO concentrations respectively measured to date in a natural vent fluidHuber and WächtershäuserReduced carbon species in modern HT vent fluids have not been measured outside of the mM range , and it 2 released by serpentinization reactions and one-C species can be constrained. C-C bond forming reactions are most kinetically favorable from formate/CO and as would be expected the equilibrium between CO and formate, a simple hydration, is obtained rapidly, while that between CO2 and CH4 is notThe redox equilibrium between H3SH and MTA were prepared from very high concentrations of reagents. Huber and Wächtershäuser’s3SH, CO, and NiSO4 or various metal sulfides was proposed to proceed through MTA as an intermediate. However, the conditions of the experiment are of questionable geochemical relevance: for example, 160 mM Na2S was employed, which is much higher than that observed in any extant natural system  and CH3SH (~10.4) with acetic acid (~4.8) at 25 °C, one would expect the Keq for TAA to be significantly higher than for MTA, which is concordant with our DFT calculations. For reference the pKa’s of ethane thiol (~10.6) and butane thiol (~10.5) are fairly close to those reported for CoASH (~9.6–10)eq values, and the abundances of higher thiols can reasonably be expected to be much lower.The effect of pH on the equilibrium constants for TAA derivatives may be attributable to pK2+ and Mg2+. It is not clear that a high, neutral or low pH environment bulk ocean is necessarily preferable for the origin of life, though in scenarios which invoke TAA or MTA, each has significant consequences.While the pH of vent fluids has probably always been locally controlled, the pH of the prebiotic oceans remains uncertain. The best geochemists have been able to infer is a minimum pH for the oceans, which is on the order of 5–6Acidic oceans do not seem to be preponderant on icy worlds in our solar system where measurement has been possible, for example on Enceladus, as inferred from mass spectrometry of plume ejecta2S to give TAA2S with ACN, thioacetamide, is also unlikely to accumulate in most environments, degrading principally to TAA under basic conditions, and acetamide under acidic onesIt is beyond the scope of this paper to examine every conceivable reaction mechanism which could lead to thioesters in hydrothermal environments. There are other routes by which TAA derivatives could be reasonably abiotically synthesized. For example the sulfhydrolysis of acetonitrile (ACN) with Het al.The addition of thiols to aldehydes followed by oxidation could also yield thioesters. However, this ignores the problem of thiol concentration already discussed and would require the presence of significant concentrations of aldehydes which are unlikely to be stable to the temperature and redox conditions prevailing in HT environments , it is unlikely such compounds could have contributed to the origin or maintenance of such assemblages, except possibly in certain specialized environments as discussed below. TAA and MTA differ significantly in terms of their stability and reactivity as a function of pH and temperature, though both are implausible prebiotic reagents for different reasons in different contexts.i.e., that life originally depended on specific environmental chemical pathways, which it gradually coopted.The variety of schemes in which TAA and MTA are implicated prompted this investigation. The large free energy changes for the hydrolysis of TAA and MTA have contributed to the notion of their potential utility as acetyl-CoA analogues in prebiotic chemistry672572626a priori reason on the basis of the kinetics of hydrolysis for blanket skepticism or rejection of theories that invoke thioesters as molecules of prebiotic importanceIn examining the kinetics of thioester exchange reactions, Whitesides and coworkers concluded that there was no In considering the plausibility of the existence of any given species, and its possible concentrations, it is useful to adopt a systems-based analysis. The sources and sinks of species are crucial considerations, as are the temporal dynamics of material transport, and chemical kinetics and equilibria in geological settings.It is difficult to categorically state that some species could have been present in any given concentration in any given environment on the primitive Earth, especially since there may have existed gradients of environmental parameters where many combinations of pH, temperature, and speciation could have been juxtaposed for variable amounts of timeThe instabilities and difficulty of synthesis of various organic compounds have been used previously to argue against the likelihood of various compounds’ accumulation and involvement in the origin of life in certain settings2.A number of extant organisms carry out reactions which initially fix CO via the Wood-Ljungdahl pathway, ultimately yielding acetyl-CoA. However, while these CoA analogs could conceivably be generated in very low steady-states abiotically, they may be unlikely feedstocks for the origin of life or primitive biology. In this study, we reacted extremely high concentrations of TAA or MTA, and found that there are no products aside from the hydrolytic ones, thus there may be relatively few reactions by which acetate equivalents could be donated by TAA or its derivatives, aside from acetyl group transfer .


The mammalian T cell receptor (TCR) orchestrates immunity by responding to many billions of different ligands that it has never encountered before and cannot adapt to at the protein sequence level. This remarkable receptor exists in two main heterodimeric isoforms: αβ TCR and γδ TCR. The αβ TCR is expressed on the majority of peripheral T cells. Most αβ T cells recognize peptides, derived from degraded proteins, presented at the cell surface in molecular cradles called major histocompatibility complex (MHC) molecules. Recent reports have described other αβ T cell subsets. These ‘unconventional’ T cells bear TCRs that are capable of recognizing lipid ligands presented in the context of the MHC-like CD1 protein family or bacterial metabolites bound to the MHC-related protein 1 (MR1). γδ T cells constitute a minority of the T cell pool in human blood, but can represent up to half of total T cells in tissues such as the gut and skin. The identity of the preferred ligands for γδ T cells remains obscure, but it is now known that this receptor can also functionally engage CD1-lipid, or immunoglobulin (Ig) superfamily proteins called butyrophilins in the presence of pyrophosphate intermediates of bacterial lipid biosynthesis. Interactions between TCRs and these ligands allow the host to discriminate between self and non-self and co-ordinate an attack on the latter. Here, we describe how cells of the T lymphocyte lineage and their antigen receptors are generated and discuss the various modes of antigen recognition by these extraordinarily versatile receptors. Immune surveillance by T lymphocytes is critical for the immune integrity of all jawed vertebrates and is imposed through an intricate armoury of functions that eliminate pathogen-infected and neoplastic cells. The T cell pool consists of several functionally and phenotypically heterogeneous subpopulations. T cells are broadly classified as αβ or γδ according to the somatically rearranged T cell receptor (TCR) they express at their surface.-reactive (GEM) T cells. iNK T and GEM T cells are dedicated to recognition of glycolipids in the context of CD1d and CD1b, respectively αβ T cells are by far the most abundant and the best-characterized circulating T cells. Most αβ T cells recognize peptides from degraded proteins bound to major histocompatibility complex (MHC) molecules at the cell surface. These peptide-MHC (pMHC)-recognizing T cells were the first to be described γδ T cells are also grouped as being ‘unconventional’, as they are not MHC-restricted and do not appear to recognize peptide antigens. One to 10% of circulating T cells express a γδ TCR, but this fraction is considerably higher in epithelial tissues. These tissues form the main portal of entry for pathogens, suggesting an important role of γδ T cells as early immune sentinels. Murine knock-out studies have demonstrated that γδ T cells have a clear role in pathogen clearance and tumour surveillance Despite the functional and phenotypical differences between subsets, all T cells arise from the same precursors and share their early differentiation history. Thymic progenitor cells seed the thymus from the fetal liver or adult bone marrow. In the thymus, these progenitors enter a complex differentiation programme which leads to irreversible acquisition of T cell identity and expression of clonally distributed, variegated TCRs. In this review, we describe the mechanisms through which MHC-restricted and MHC-independent TCRs are generated and discuss recognition of antigen by distinct T cell subsets. We also re-examine recent findings on the more ‘unconventional’ subsets.tra), discrete variable (V) and junctional (J) gene segments are recombined and juxtaposed to a constant (C) segment (trb) is similar, but includes an additional diversity (D) segment and one of two C segments can be appended to the rearranged TCR-β chain  NK T cells are selected on CD1d-expressing CD4mhc locus was first described more than half a century ago as the set of genes which determine the outcome of tissue transplantation in congenic mice. It is now clear that the products of the mhc have evolved to allow T cells to perform highly specific functions which are crucial to adaptive immunity and host defence as a whole. The mhc locus is the most gene-dense and the most polymorphic region known to date, with more than 12 000 different alleles already described in humans mhc ensures diversity in peptide presentation at the population level.The cardinal feature of αβ T cells is the recognition of peptides derived from self and foreign proteins in the context of self-MHC molecules. The 2 microglobulin (β2m) protein  and MHC class II (MHC-II). There are three classical human MHC-I genes . These genes encode a membrane-spanning α-chain associated with the non-polymorphic β protein . Polymor protein  37. The 1α2 binding cleft , it was shown that the selection of MHC-specific TCRs was strictly governed by the T cell co-receptors CD4 and CD8. CD4 and CD8 act as antigen co-receptors by binding to invariant regions of the MHC-II and MHC-I, respectively, at sites distinct from the TCR docking platform . The cytmhc locus is an example of extreme polymorphism. The vast majority of polymorphic residues in MHC proteins cluster around the peptide-binding cleft to suggest that this diversity is upheld to expand the variety of peptides that can be displayed to the immune system As described above, the It is becoming apparent that effective immune cover requires that each TCR must allow the T cell that bears it to respond to a large array of different peptide ligands The transfer of TCR genes into recipient host T cells followed by the adoptive transfer of these cells to patients allows the passive transfer of immunity The list of unconventional T cells that do not recognize pMHC ligands is growing steadily, further demonstrating the versatility of the TCR. Recent discoveries have highlighted the existence of αβ T cells that recognize non-peptide ligands. Approximately 10% of all αβ T cells are now thought to recognize lipid antigens. A further 10% of human αβ T cells appear to recognize bacterial metabolites.Many human αβ T cells have been identified recently that respond to non-peptide antigens presented by MHC class I-related molecules from the CD1 protein family CD1d–lipid complexes bind to TCRs that are expressed by the innate-like NK T cells GEM T cells recognize mycobacteria-derived (glyco)lipids in the context of CD1b, a molecule which has the potential to accommodate the largest and most diverse lipid ligands among the CD1 protein family Contrary to CD1b–d, CD1a can bind lipids lacking a polar headgroup. These hydrophobic lipid antigens are then not recognized directly by the TCR, but rather allow CD1a to adapt to a TCR-activating conformation et al. It has been shown recently that MAIT cells recognize intermediates in the riboflavin biosynthesis pathway bound to the MHC-like molecule MR1 trg and trd loci is programmed developmentally and different γδ T cells carrying distinct TCR-γ and TCR-δ rearrangements arise in successive waves that colonize different tissues during embryonic development Surprisingly little is known about human γδ T cells or the ligands they recognize. Unlike αβ T cells, γδ T cells exhibit strict tissue-specific localization, which is determined by the identity of the rearranged TCR. This is because gene rearrangement at the +Vδ2+ T cells have been shown to recognize small pyrophosphate intermediates of the lipid biosynthetic pathway used by some bacteria +Vδ2+ T cells by an MHC-like molecule. Recently the candidate for a pyrophosphate antigen-presenting molecule has been narrowed down to butyrophilin 3A1 (BTN3A1), an immunoglobulin-like molecule encoded in the MHC I locus. Crystallographic studies revealed that pyrophosphate antigens can be bound either in a shallow extracellular pocket of BTN3A1 and presented directly to T cells Most progress with γδ TCRs has been made with the predominant subset of γδ T cells found in human peripheral blood that express a TCR made from the Vγ9 and Vδ2 genes. Vγ9et al. Similarly to ‘unconventional’ αβ TCRs, γδ TCRs can mediate recognition of lipids in the context of CD1d EPCR is not the only example of a γδ TCR ligand recognized in a cellular stress context. It has been known for some time that a portion of human γδ T cells can bind MHC class I polypeptide-related sequence (MIC) A It has been known for several decades that the vast majority of TCRs recognize MHC-bound peptides. Recent developments have highlighted the astonishing versatility of this receptor . Indeed,


Although various studies to provide insight into dipole moment behaviour, such as phase transition, order and disorder states, have been reported, macroscopic spontaneous polarization has been mainly discussed so far. Here, visualization of the electric dipole arrangement in layered ferroelectrics Bi2SiO5 by means of combined analysis of maximum entropy charge density and electrostatic potential distribution analysis based on synchrotron radiation X-ray powder diffraction data is reported. It was found that the hierarchical dipole orders, the weak-ferroelectric and ferroelectric configurations, were observed in the Bi2O2 and the SiO3 layers, respectively, and the ferrielectric configuration was realised by the interlayer interaction. This discovery provides a new method to visualize the local polarization in ferroelectric materials.Electric dipole engineering is now an emerging technology for high electron-mobility transistors, ferroelectric random access memory and multiferroic devices  Recently, electrostatic potential (EP) analysis based on electron charge density (ECD) using the maximum entropy method (MEM) has been developed for the characterization of specific features originating from the electrostatic field/force on the microscopic scale  has attracted much attention as an alternative to the traditional lead-based ferroelectric materials with a phase-transition temperature (Tc) of 673 K. BSO has an Aurivillius-like structure consisting of the [Bi2O2]2+ layer and [SiO3]2− layer  of 14.5 µC cm−2 along the SiO3 chain (c-axis) was predicted by first-principles calculations, while those along the a- and b-axes, Pa and Pb, are estimated to be small, 0.1 µC cm−2 and 0 µC cm−2, respectively  Å to reduce absorption effects caused by the heavy atom (Bi) in the sample. The diffraction data were collected for 45 min on an image plate installed in the large Debye–Scherrer camera.Synchrotron radiation X-ray powder diffraction measurements of BSO were performed at BL02B2 beamline at SPring-8 with a large Debye–Scherrer camera to obtain high counting statics for accurate structure analysis ] is composed of the nucleus charge [Unuc(r)] and the electron charge [Uele(r)] components. In this study, ECD and EP were visualized using the OpenDx program provided by IBM Visualization Data Explorer. The procedure for the polarization calculations is described in the supporting information.Determination of the precise structure was carried out by Rietveld refinement. Details of the process and the results are described in the 3.4 square pyramids in the Bi2O2 layer and the SiO3 tetrahedra in the SiO3 layer . The projected values of the polarization along the a- and c-axis, Pa and Pc, in the SiO3 layer are 1.4 (1) µC cm−2 and 27.3 (1) µC cm−2, respectively. It should be noted that Pb is zero due to the inversion symmetry operation along the b-axis. On the other hand, the Bi2O2 layer has a small but distinct polarization value in spite of the antiferroelectric order: the projections of the polarization in the Bi2O2 layers were −1.8 (1) µC cm−2 for Pa and −3.8 (1) µC cm−2 for Pc. This originates from the asymmetric distortion of the Bi2O2 pyramids, meaning that the Bi–O dipoles with antiparallel configuration do not fully cancel out the polarization in the layer: this is regarded as the weak-ferroelectric configuration, as shown in Fig. 2(c)2O2 layer aligns in the antiparallel direction to the polarization in the SiO3 layer, the distortion in the Bi2O2 layer is suggested to be induced by the large polarization of the SiO3 layer for reducing the electrostatic energy in the crystal. The individual dipole moment [26.8 (3) µC cm−2 and 27.0 (4) µC cm−2] of Bi–O is comparably large with that of the SiO3 fragment [27.3 (1) µC cm−2], although the net value is as small as 4.2 (1) µC cm−2 owing to the antiparallel configuration of the Bi–O dipoles.The SiOPa and Pc of BSO were estimated to be 0.3 (2) µC cm−2 and 23.5 (1) µC cm−2, respectively. Pb was zero because of the symmetry operation of the crystal structure. The value of Pa is roughly consistent with that predicted by theoretical calculation (0.1 µC cm−2) and that determined by P versus E measurements (0.8 µC cm−2)  µC cm−2]. The result shows that the ECD/EP analysis using precise X-ray diffraction data can derive the local electric dipole moment in the crystal as well as in the polarization values from small amounts (less than 0.1 mg) of powder samples, and values are consistent with those predicted by the complete picture based on the Berry-phase theory. It should be noted that the values of polarization based on the point charge model, where the electron charge of atoms was assigned to each atomic position obtained by Rietveld analysis, largely deviated from any other results of theoretical prediction, PversusE measurements and the ECD/EP analysis; this result shows that the use of the ECD distribution is essential for estimation of accurate values of polarization. The method of ECD/EP analysis is, therefore, useful for characterization and design of newly synthesized dielectric materials, and thus for the development of emerging dielectric materials.The total 2O2 and the SiO3 layer, respectively. Next, the antiparallel arrangement between the net small dipoles in the Bi2O2 layer and the large dipoles in the SiO3 layers reduces the interlayer electrostatic interaction; this configuration is regarded as an interlayer ferrielectric ordering. In addition, the neighbouring Bi2O2 and SiO3 layers form a pair, namely, the dimerization of the layers . In this distortion the dipoles in the neighbouring layer being aligned in the antiparallel configuration become close to reduce the electrostatic energy. In actual fact, the cohesive energy of the low-temperature ‘ferroelectric’ phase is lower than that of the high-temperature paraelectric phase by 23.1 meV in Bi2SiO5  and the ferroelectric configuration are realised in the BiFigs. 2c and S3a.3 layer, and large polarization is stabilized by the antiparallel configuration with the Bi2O2 layer.The ECD/EP analysis can visualize the properties of covalency and polarization in the crystal using a tiny amount of powder sample. In addition, the method demonstrates its ability to visualize local polarization which cannot be detected by the macroscopic measurements in principle. In the case of BSO, for instance, a large dipole moment should be induced at the SiO4.2SiO5: the weak ferroelectricity in the Bi2O2 layer, the ferroelectric order in the SiO3 layer, and the ferrielectric order between the Bi2O2 and SiO3 layers. The results suggest that ECD/EP analysis is a useful method to visualize the local polarization based on X-ray powder diffraction experiment.In summary, we have discovered a new approach to the visualization of the local electric dipole moments and their orders in a crystal by means of the combined analysis of ECD using MEM and EP distribution analysis based on synchrotron radiation X-ray powder diffraction data. Application of this method revealed hierarchical dipole ordering in Bi10.1107/S2052252514008008/ro5001sup1.pdfDetermination of the local and the total polarization values and precise structural parameters; covalency revealed by MEM charge density distribution analysis; fragments determined by electrostatic potential boundary. DOI: