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This paper presents a 20-Gb/s automatic gain control (AGC) amplifier in a 0.18-μm SiGe BiCMOS for high-speed applications. The proposed AGC amplifier compactly consists of a folded Gilbert variable-gain amplifier (VGA), a post amplifier (PA), a 50-Ω output buffer, and AGC loop including an open-loop peak detector (PD), a RC low-pass filter (LPF), and an error amplifier (EA). The AGC amplifier achieves the broadband characteristic by utilizing inductive peaking and capacitive degeneration as well as fT-doubler techniques to overcome the large parasitic capacitances. The proposed AGC circuits together with a linear VGA exhibits a wide gain control range of 45 dB for the received signal strength indication (RSSI). The measured AGC amplifier achieves a maximum gain of 21 dB and a -3-dB bandwidth (BW) of 20.6 GHz, which can support up to 25.4-Gb/s data rate. For the pseudorandom bit sequence (PRBS) length 231–1 with a bit-error rate (BER) of 10−12 at 20 Gb/s, the measured input dynamic range is 26 dB (20–400mVpp) and the peak-to-peak data jitter is less than 8 ps. The AGC amplifier consumes a power of 160 mW from a 3.3-V supply voltage and occupies an area of 850 μm × 850 μm.

The brain of the domestic pig (Sus scrofa domesticus) has drawn considerable attention due to its high similarities to that of humans. However, the cellular compositions of the pig brain (PB) remain elusive. Here we investigated the single-nucleus transcriptomic profiles of five regions of the PB (frontal lobe, parietal lobe, temporal lobe, occipital lobe, and hypothalamus) and identified 21 cell subpopulations. The cross-species comparison of mouse and pig hypothalamus revealed the shared and specific gene expression patterns at the single-cell resolution. Furthermore, we identified cell types and molecular pathways closely associated with neurological disorders, bridging the gap between gene mutations and pathogenesis. We reported, to our knowledge, the first single-cell atlas of domestic pig cerebral cortex and hypothalamus combined with a comprehensive analysis across species, providing extensive resources for future research regarding neural science, evolutionary developmental biology, and regenerative medicine.

Olfaction, the sense of smell, is a fundamental trait crucial to many species. The olfactory bulb (OB) plays pivotal roles in processing and transmitting odor information from the environment to the brain. The cellular heterogeneity of the mouse OB has been studied using single-cell RNA sequencing. However, the epigenetic landscape of the mOB remains mostly unexplored. Herein, we apply single-cell assay for transposase-accessible chromatin sequencing to profile the genome-wide chromatin accessibility of 9,549 single cells from the mOB. Based on single-cell epigenetic signatures, mOB cells are classified into 21 clusters corresponding to 11 cell types. We identify distinct sets of putative regulatory elements specific to each cell cluster from which putative target genes and enriched potential functions are inferred. In addition, the transcription factor motifs enriched in each cell cluster are determined to indicate the developmental fate of each cell lineage. Our study provides a valuable epigenetic data set for the mOB at single-cell resolution, and the results can enhance our understanding of regulatory circuits and the therapeutic capacity of the OB at the single-cell level.

Purpose To characterize the genetic landscape of patients with suspected retinitis pigmentosa (RP) in the Chinese population. Design Cohort study. Participants A total of 1243 patients of Chinese origin with clinically suspected RP and their available family members (n = 2701) were recruited. Methods All patients and available family members were screened using multigene panel testing (including 586 eye disease-associated genes), followed by clinical variant interpretation. Main Outcome Measures Diagnostic yield, the 17 most commonly implicated genes, age at onset, de novo mutations, and clinical usefulness of genetic testing. Results Overall, 72.08% of patients received a molecular diagnosis, and the 17 top genes covered 75.63% of diagnostic cases. Diagnostic yield was higher among patients in the early-onset subgroup (≤5 years old, 79.58%) than in the childhood or adolescence-onset subgroup (6–16 years old, 73.74%) and late-onset subgroup (≥17 years old, 65.99%). Moreover, different genes associated with different onset ages and subgroups with different onset ages showed a diverse mutation spectrum. Only 11 de novo mutations (3.18%) were identified. Furthermore, 16.84% of the patients who received a molecular diagnosis had refinement of the initial clinical diagnoses, and the remaining 83.16% received definite genetic subtypes of RP. Conclusions This large cohort study provides population-based data of the genome landscape of patients with suspected RP in China. The diagnostic yield was significantly higher than that in previous studies, and the mutation spectrum is completely different with other populations. Genetic testing improves the chance to establish a precise diagnosis, identifies features not previously determined, and allows a more accurate refinement of risk to family members. Our results not only expand the existing genotypic spectrum but also serve as an efficient reference for the design of panel-based genetic diagnostic testing and genetic counseling for patients with suspected RP in China.

Large Eddy Simulation (LES) is used to study natural circulation flow in a sealed rod bundle with a Rayleigh number (based on height) of approximately 10 11 and a fluid Prandtl number of 0.74. Natural convection boundary layer development is observed on both the heating rods and cooling containment surfaces. The development of the boundary layers is key to the flow and heat transfer characteristics of the system. As the flow descends on the containment surface, the boundary layer gradually develops and transitions from laminar to turbulent flow, with transition occurring close to the bottom-end. Laminar flow at the containment is well represented by a flat plate similarity solution for buoyant flow and the Nusselt number correlation is akin to that for a flat isolated vertical surface. This indicates the boundary layer development on this surface is similar to an isolated vertical surface. On the rods boundary layer development occurs much earlier and is affected by turbulence convected from the containment surface. Laminar flow here compares well against a slender cylinder similarity solution. In the developed region, the Nusselt number correlation has a Rayleigh number dependency similar to that for a rectangular cavity.

Quartz-vein-type wolframite deposits are a primary type of tungsten deposits. Traditionally, F and Cl were considered as important agents in tungsten transportation during ore formation process. However, ore-forming fluids enriched in CO2 were commonly observed in natural fluid inclusions associated with quartz-vein-type wolframite deposits, indicating that carbonate or CO2 could be important for their formation. In this paper, we report experiments of the dissolution and crystallization of huebnerite in the MnWO4-Li2CO3 (or Na2CO3)–H2O system using a hydrothermal diamond-anvil cell (HDAC). The results showed that MnWO4 dissolved in alkali-carbonate aqueous solutions and, in some cases, in associated carbonate melts during heating, and subsequently, huebnerite crystallized into needle and column shaped crystals during cooling. In situ Raman spectra obtained during heating of the experimental charge in the sample chamber of the HDAC showed that WO42− was the only tungsten-bearing ion detected in the carbonate melt or aqueous solution. The dissolution of MnWO4 mainly attributed to the alkaline environment in the alkali-carbonate aqueous solution. Furthermore, the weak alkali condition in the carbonate solutions enhanced the crystallization of huebnerite when the temperature and pressure were decreased. The experimental results indicate that although the crystallization temperature–pressure conditions of huebnerite vary in a wide range, conditions lower than approximately 200 MPa and 450 °C are not favorable for huebnerite crystallization. Our experimental results also suggest that the alkali-carbonate aqueous solution could serve as a medium for the transport of tungsten in the ore-forming process.

The Renli deposit is the largest known pegmatite-type Ta–Nb deposit in south China. Its rare-metal pegmatites show regular zoning of pegmatite types and rare-metal mineralization assemblages from northeast to southwest. One hundred and forty major outcropping pegmatite dikes throughout the deposit can be approximately divided into four zones outward from the Mufushan batholith: microcline pegmatite zone (P1); microcline–albite pegmatite zone (P2); albite pegmatite zone (P3); and albite–spodumene pegmatite zone (P4). The sizes of the dikes decrease with distance from the batholith, and their rare-metal mineralization type changes as follows: Be → Nb–Ta (–Be) → Li (–Nb–Ta). Field geological characteristics, chronological and Lu–Hf and Sr–Nb–Pb isotopic studies indicate that these rare-metal pegmatites have a close petrogenetic relationship with the Mufushan complex granitic intrusions. However, because of the similarities in geochemical characteristics, magma source properties, and emplacement ages of these different granitic intrusions, identifying the parental rock of rare-metal pegmatites is challenging. Muscovites are common throughout the granitic intrusions and four types of pegmatites in the Renli deposit, and are intimately associated with rare-metal mineralization. The geochemistry of muscovite obtained from granites and pegmatites can be used to demonstrate the parental relationships of rare-metal pegmatites and Mufushan granites, allowing pegmatite evolution trends and the mineralization potential of the Renli deposit to be evaluated. The K/Rb versus Cs, Rb, Li, Nb, and Ta ratios and Ta/Nb versus Li, Ta, and TiO2 ratios in muscovites from the granites and pegmatites show that they form an association with the following sequence of evolution: biotite monzogranite → two-mica monzogranite → microcline pegmatite → microcline–albite pegmatite → albite pegmatite → albite–spodumene pegmatite. The above complete evolution sequence represents the magmatic stage of the deposit and the lepidolite-quartz core in pegmatite with well internal zoning represents the fluid-rich stage of the deposit. The Al4Si–3□–1 exchange vector (where □ represents a vacancy) is shown to have played an important role in the first magmatic stage of the Renli deposit when compositional changes in Li-poor muscovite formed in the magmatic stage involved this substitution. During the late fluid-rich stage formed by highly differentiated magma at the end of the magmatic evolution of the deposit, Li was incorporated into micas by Li3Al–1□–2. Many pegmatite dikes with transitional boundaries can be observed in the outcrops of two-mica monzogranite (RLG2), and geochemical characteristics of muscovite suggest that this monzogranite show the highest differentiation degree in Renli granites, whose average K/Rb and Ta/Nb ratios are close to those of the Renli pegmatites. This indicates that the two-mica monzogranite (RLG2) has the closest petrogenetic relationship with the Renli rare-metal pegmatites. Combined with the data from this and previous studies, the K/Rb ratio, Li and Cs contents of muscovite can be used to distinguish the barren pegmatite and different types (Be, Nb–Ta, or Li type) of rare-metal pegmatites to a certain degree. Therefore, muscovite can indicate the metallogenic type and economic potential in a pegmatite-type rare-metal deposit.

This paper investigates the impulsive stabilization problem of fractional differential systems (FDSs in short). Both the global exponential stability and ultimate boundedness criteria are established using Lyapunov functions, algebraic inequality techniques and boundedness of Mittag-Leffler functions. It is shown that unstable and unbounded FDSs can be stable and bounded respectively under impulsive control. Examples and simulations are also provided to demonstrate the effectiveness of the derived theoretical results.

Highly turbulent natural circulation in an enclosed tall rod bundle is investigated using Large Eddy Simulation (LES). The rod bundle consists of 36 heated rods and an insulated central tubeenclosed by a cooled containment wall. This geometry is directly relevant to nuclear fuel bundles and generic heat exchangers. For nuclear fuel bundles, natural circulation is of importance in accident scenarios. A 60° azimuthally periodic sector of the bundle is modelled. The Rayleigh number based on the height is 7.6 × 10 12 and 1.23 × 10 13 for the two cases studied. The flow, turbulence, and thermal characteristics of the system show strong distinct features in the top, middle, and bottom regions (about 0.2, 0.6, and 0.2 splits), which are strongly influenced by the vertically developing buoyancy-driven boundary layer on the containment surface. The flow in the top region is largely stagnant with strong thermal stratification and weak cross flow. A laminar boundary layer is however formed on the containment wall which later transitions to turbulence. This turns out to be the dominant flow feature in the rod bundle. The velocity profile and heat transfer in this top region are well represented, respectively, by a similarity solution for laminar flow and a well-established Nusselt correlation for an unconfined flat plate. In the middle-height region, the flow can be naturally split into an outer flow and a central flow zone. The former resembles the flow in a simple, rectangular, asymmetrically heated/cooled cavity, and the heat transfer to the containment is well represented by a turbulent natural convection correlation. The central flow zone largely resembles mixed convection in a heated upwards pipe/channel flow, though the entrainment of fluid from the outer zone means that the flow accelerates axially until the middle-height. Irrespective of the differences in the two zones, the near-wall behaviour of the flow and thermal fields on the rods and containment wall shows a strong similarity at different heights as well as between the two zones. They are also shown to be consistent with buoyancy-driven flows in simple geometries. In the bottom region, the flow is dominated by an impinging jet from the containment wall and a resultant cross flow from the outer zone to the inner one.

The Yichun Ta-Nb deposit, which is located in Jiangxi Province, South China, can be divided into four lithological zones (from bottom upward): two-mica granite, muscovite granite, albite granite, and lepidolite-albite granite zones. It remains controversial whether these distinct vertical zones were formed through late magmatic-hydrothermal metasomatic alteration or fractional crystallization of magma. To investigate the evolution mechanism of rock- and ore-forming fluid in this deposit, we studied fluid and melt inclusions in quartz and lepidolite in these four granite zones. These fluid inclusions are mainly composed of H2O-NaCl, and have homogenization temperatures ranging from 160 °C to 240 °C, with densities between 0.86 and 0.94 g/cm3 and salinities between 0.5 and 6.5 wt% NaCl equivalent. Raman spectroscopic analyses showed that the daughter minerals contained in silicate melt inclusions are mainly quartz, lepidolite, albite, muscovite, microcline, topaz, and sassolite. From the lower to upper granite zones, the albite contents in silicate melt inclusions increase, while the muscovite contents decrease gradually until muscovite is substituted by lepidolite in the lepidolite-albite granite zone. Additionally, the calculated densities of the silicate melt inclusions exhibit decreasing trends from bottom upward. The total homogenization temperatures of silicate melt inclusions, which were observed under external pressures created in the sample chamber of a hydrothermal diamond-anvil cell, decreased from 860 °C in the lower lithological zone to 776 °C in the upper lithological zone, and the initial melting temperatures of solid phases were 570–710 °C. The calculated initial H2O contents of granitic magma showed an increasing trend from the lower (∼2 wt% in the two-mica granite zone) to the upper granitic zones (∼3 wt% in the albite granite zone). All of these features illustrate that the vertical granite zones in the Yichun Ta-Nb deposit formed through the continuous fractional crystallization of the granitic magma. Additionally, the low H2O contents and gradual enrichment of incompatible elements (F, B, Li, Ta, Nb, etc.) in the residual granitic magma favored the formation of a granite-type Ta-Nb deposit.

Ginseng is one of the most widely used natural medicines in the world. Recent studies have suggested Panax ginseng has a wide range of beneficial effects on aging, central nervous system disorders, and neurodegenerative diseases. However, knowledge about the specific bioactive components of ginseng is still limited. This work aimed to screen for the bioactive components in Panax ginseng that act against neurodegenerative diseases, using the target cell-based bioactivity screening method. Firstly, component analysis of Panax ginseng extracts was performed by UPLC-QTOF-MS, and a total of 54 compounds in white ginseng were characterized and identified according to the retention behaviors, accurate MW, MS characteristics, parent nucleus, aglycones, side chains, and literature data. Then target cell-based bioactivity screening method was developed to predict the candidate compounds in ginseng with SH-SY5Y cells. Four ginsenosides, Rg2, Rh1, Ro, and Rd, were observed to be active. The target cell-based bioactivity screening method coupled with UPLC-QTOF-MS technique has suitable sensitivity and it can be used as a screening tool for low content bioactive constituents in natural products.

Laser Raman spectroscopic analyses showed the occurrence of cristobalite, together with carbonic aqueous fluid phases, in the crystal-rich inclusions (CIs) hosted in spodumene in Jiajika pegmatite deposit, China. In these CIs, cristobalite always coexists with zabuyelite, and occasionally with other minerals, including calcite, spodumene, and possibly cookeite. The rare occurrences of cristobalite in plutonic rocks are commonly considered to be resulted from the lack of H2O, which was thought to be the catalyzer for the conversion of cristobalite to quartz. However, this assumption is not supported by our observed coexistence of cristobalite with aqueous fluid in the CIs of Jiajika pegmatite deposit. The results of microthermometric analyses showed that the carbonic aqueous fluids in CIs had salinities of less than 7 wt.% NaCl equivalent, in which the CO2 phase(s) occupied 60–80 vol.% with the bulk CO2 densities of near 0.70 g/cm3. Therefore, the estimated internal pressure of CIs are between 200 and 290 MPa at the initial dissolving temperature of daughter minerals (cristobalite at ~ 400 °C), much lower than the entrapment pressures of at least 440 MPa. The occurrences of cristobalite in CIs could be ascribed to (1) the pressure decrease within CIs from the entrapment pressures of greater than 440 MPa to 200–290 MPa at ~ 400 °C, mainly resulted from the crystallization of zabuyelite, and (2) the extension of the cristobalite stability to low temperatures due to the presence of lithium and H2O in the inclusions. More study is needed for the formation mechanisms of cristobalite in plutonic rocks and the effect of H2O on the conversion of cristobalite to quartz.

The Zhawulong ore field hosts lots of rare-element pegmatite dikes and is an important producing area for lithium resources in the Songpan–Ganze orogenic belt (SGOB), east Tibet. This paper aims to evaluate the sources and ore-forming processes for granite and pegmatite in the Zhawulong ore field, as well as the petrogenetic links between these rocks, using petrography, whole-rock major and trace-element analysis, and Sr–Nd–Hf isotope analysis. In this ore field, pegmatites are common as dike swarms that emanate from the external and/or internal contact zone of the Zhawulong granitic pluton and strata of the Triassic Xikang group, showing close spatial relationships. Measured values of K/Rb vs. Zr, Hf, and Cs contents indicate geochemical affinities between granite and pegmatite, which suggests that the pegmatite was generated by processes involving high fractional crystallization from the residual parental magma of the host granite. Additionally, the granite have high (87Sr/86Sr)i values (0.711064 to 0.716105), negative eNd(t) values (−9.6 to −9.1) and eHf(t) values (−32.6 to −2.0), and ancient Nd and Hf model ages (1.2–3.1 Ga), which indicate a continental crustal source. Metasedimentary rocks of the Xikang group are rich in Li (~95 ppm), Rb (~124 ppm), Nb (~15 ppm), and Cs (~17 ppm), and their rare-earth element (REE) patterns show moderate enrichment in light REEs and a negative Eu anomaly (Eu/Eu* = ~0.64), revealing characteristics similar to those of granite. The coeval nature and close spatial relationships between the Zhawulong granite and other syn-orogenic S-type granites indicate that the formation of this granite was related to crustal melting. The petrology and geochemical signatures of the Zhawulong rare-metal-bearing granite–pegmatite imply that it was generated by the partial melting of metasedimentary rocks during the Late Triassic orogeny assembly and was further enriched in Li through processes involving high fractional crystallization.

Purpose Stargardt disease (STGD) is the most frequent cause of hereditary macular dystrophy in childhood. Variants in the ABCA4, ELOVL4, PROM1, BEST1, and PRPH2 genes have been detected in patients with autosomal recessive or dominant STGD. This study was aimed at identifying the novel disease-associated variants in Chinese patients with STGD. Methods Ten Chinese families and two sporadic cases with STGD (n = 32) were enrolled in the study. All subjects underwent genetic analysis with next-generation sequencing (NGS), which was based on a specially customized capture panel targeting exons and untranslated regions (UTRs) of 792 genes related to common hereditary ophthalmopathy. Variants were analyzed to assess possible pathogenicity. Results Fourteen disease-associated variants of ABCA4 were detected in 9 Chinese families with autosomal recessive STGD, including 11 pathogenic variants and 3 likely pathogenic variants. Variant c.4253 + 4C > T in ABCA4 was identified as one de novo variant. Of the 14 distinct variants in ABCA4, 7 novel variants were found. In addition, one known variant of PROM1, c.1117C > T (p.Arg373Cys), was detected in one family and one sporadic case with autosomal dominant STGD, respectively. One novel missense variant of ELOVL4, c.59A > G (p.Asn20Ser), was found in one sporadic case with autosomal dominant STGD. The potential deleterious effects of these novel variants were confirmed through intensive analysis. Conclusion By panel-based NGS, 8 novel disease-associated variants are identified in two genes responsible for STGD, including ABCA4 and ELOVL4. Our results further extend the mutation spectrum of these two genes in Chinese patients with STGD. One ABCA4 c.4253 + 4C > T variant is identified as a de novo splicing variant.

The Jiangnan orogenic belt hosts many rare-metal deposits that exhibit close ore-forming ages and similar geological backgrounds and is an important Li–Be–Nb–Ta concentration belt located in eastern China. However, the metallogenic mechanism and regularity of these rare-metal deposits have not yet been reported in detail because of the lack of accurate geochronological data and systematic studies on the sources of metallogenic materials. The giant Renli rare-metal deposit, located at the south margin of the Mufushan batholith in the central Jiangnan orogenic belt, is one of the few high-grade granitic-pegmatite-type Nb–Ta deposits in China. Columbite–tantalite U–Pb dating has been developed as a more robust method when compared with the traditional dating methods to constrain the timing of rare-metal mineralization. Six columbite grains, obtained from the microcline–albite pegmatite of the Renli deposit, exhibit a concordant laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) U–Pb age of 133.0 ± 2.6 Ma, which denotes the Nb–Ta mineralization age. The zircon grains from the columbite-bearing microcline–albite pegmatite subjected to different degrees of alteration by the hydrothermal fluids yield a concordant LA–ICP–MS U–Pb age of 131.2 ± 2.4 Ma, which can be considered to be the age of newly magmatic–hydrothermal growth and recrystallization under the transitional magmatic–hydrothermal conditions observed in case of the Renli deposit. Furthermore, the zircon grains from the host biotite monzogranite yield concordant LA–ICP–MS U–Pb ages of 140.7 ± 0.7 and 140.3 ± 0.7 Ma, whereas the zircon grains from the host two-mica monzogranite yield a concordant LA–ICP–MS U–Pb age of 138.3 ± 0.3 Ma, denoting the intrusion timing of two types of host Mufushan granites of the pegmatite dykes. Finally, the zircon grains from two schist samples of the Lengjiaxi Group yield concordant LA–ICP–MS U–Pb ages of 825.9 ± 5.6 and 834.4 ± 5.3 Ma, constraining the maximum age for the termination of deposition. These ages constitute a clear intrusion-cooling-hydrothermal time series with respect to the Renli deposit. Zircon can retain the original magmatic isotopic composition and is extensively used to trace the petrogenetic processes because it is quickly crystallized from magma. The Mufushan granite and rare-metal pegmatite exhibit consistent negative eHf(t) values (mean eHf(t) values of −7.2 and −7.3, respectively), and their two-stage model ages exhibit similar distribution patterns when compared with that exhibited by the Lengjiaxi Group. Furthermore, the Mufushan granite shows the typical geochemical characteristics of the crustal-derived granite. Thus, the rare-metal pegmatite and host granite of the Renli deposit were concluded to be sourced from the partial melting of the Lengjiaxi Group metasedimentary strata. The compressive torsional nature of the Gajiang fault zone, widespread occurrence of the S-type granite, and absence of basaltic rocks suggest that the central-to-eastern part of the Jiangnan orogenic belt was in a subduction setting during the Early Cretaceous. Thus, this economically important Early Cretaceous (ca. 133–129 Ma) rare-metal metallogenic belt was formed owing to the development of the Jiangnan orogenic belt, and the thick Lengjiaxi Group metasedimentary strata provided the metallogenic material source.

Multidrug-resistant Acinetobacter baumannii becomes an increasing challenge due to the overuse of antibiotics. Combination therapies are considered as effective options to overcome this matter. The present study was to investigate the synergistic activity of meropenem combined with other antibiotics in vitro and in vivo. Checkerboard assay and time-kill assay were performed to study the combination effects in vitro. For the animal model, a murine sepsis model injected with inoculums intraperitoneally was used. Susceptibility test showed that all the twelve strains in this study were resistant to most of the antibiotics except rifampicin. In combination, meropenem plus rifampicin exhibited synergistic activity against six of twelve strains. In the sepsis model, meropenem monotherapy had no therapeutic effect in this model while it can enhance the activity of rifampicin in both survival rate and bacterial clearance from blood. Moreover, combination therapy significantly reduced plasma IL-6 levels compared with rifampicin monotherapy. Pharmacokinetic analysis of rifampicin was also performed in this study. These data above showed that there was synergistic activity between meropenem and rifampicin against multidrug-resistant Acinetobacter baumannii both in vitro and for experimental model of sepsis. It suggested that combining meropenem with rifampicin may be appropriate in treating multidrug-resistant Acinetobacter baumannii infections.

Elemental sulfur, as a transient intermediate compound, by-product, or catalyst, plays significant roles in thermochemical sulfate reduction (TSR) reactions. However, the mechanisms of the reactions in S-H2O-hydrocarbons systems are not clear. To improve our understanding of reaction mechanisms, we conducted a series of experiments between 200 and 340 degrees C for S-H2O-CH4, S-D2O-CH4, and S-CH4-1m ZnBr2 systems in fused silica capillary capsules (FSCCs). After a heating period ranging from 24 to 2160 h (hrs), the quenched samples were analyzed by Raman spectroscopy. Combined with the in situ Raman spectra collected at high temperatures and pressures in the S-H2O and S-H2O-CH4 systems, our results showed that (1) the disproportionation of sulfur in the S-H2O-CH4 system occurred at temperatures above 200 degrees C and produced H2S, SO42-, and possibly trace amount of HSO4-; (2) sulfate (and bisulfate), in the presence of sulfur, can be reduced by methane between 250 and 340 degrees C to produce CO2 and H2S, and these TSR temperatures are much closer to those of the natural system ( 200 degrees C that can be reached by deep drilling for hydrocarbon resources. (C) 2013 Elsevier Ltd. All rights reserved.

Continuous SiC fiber reinforced copper matrix composites were fabricated at three different temperatures by fiber-coating method (FCM) with or without Ni interlayers. Ni and Cu coatings were prepared by electroplating, respectively. The tensile strengths at room temperature were established for the composites. The fracture surfaces, fiber surfaces, SiC f /Ni/Cu interface and phase composition were analyzed by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD). The results indicate that the tensile strengths of the composites with Ni interlayers prepared below 700 °C changed little in comparison with those of the composites without Ni interlayers, while those of the composites with Ni interlayers prepared at 800 °C were drastically degraded. The great degradation was caused mainly by two reasons. One is that Ni resulted in serious degradation of the strength of SiC fibers (Ni not only induced the graphitization of carbon coatings of SiC fibers, but also reacted with interior SiC to form Ni silicides and graphite), the other is that extensive interfacial reaction between Ni and SiC fiber reduced the interfacial bonding strength due to the microcracks generated in the matrix near the interface.

The interfacial bonding strength of SiC fiber reinforced copper matrix composites is extremely weak. Using Ti or other metallic elements such as Fe, Ni, Mo can improve the fiber/matrix bonding strength because these elements can form carbides or an interdiffusion zone between the fiber and the matrix though a heat treatment. In this paper, a TiC reaction layer or Ni interlayer is introduced as a binder, and thermal residual stresses (TRS) in the SiC fiber, TiC or Ni interlayers, and matrix are simulated by means of finite element method. The results indicate that the matrix undergoes significant plastic deformation when the composite is cooled to room temperature from the bonding temperature, and the residual plastic strains are highest around the interlayers and decrease as distance from the interlayer increases; the values and distributions of hoop stresses and Von Mises stresses in the matrix are nearly identical when different interlayers are used , while the magnitudes of these stresses are significantly different in different kinds of interlayers. The distribution characteristics of axial residual stresses in the matrix change when different interlayers are used, and Ni is superior to TiC as the axial stresses greatly decrease near the axial end of the composite.

Three groups of SiC f /Ti/Cu composites were prepared under conditions of 650 °C + 105 min (sample 1#), 750 °C + 85 min (sample 2#) and 840 °C + 50 min (sample 3#), respectively, by foil-fiber-foil method (FFF), and their room temperature tensile strengths were established. The aim is to model the reactive bonding states between Ti and SiC fiber and between Ti and Cu when Ti is used as interfacial adhesion promoters in SiC f /Cu–matrix composites. The fracture surfaces, SiC f /Ti interfaces and Ti/Cu interfaces were investigated by scanning electron microscopy (SEM), optical microscopy and energy dispersive spectroscopy (EDS). The tensile tests show that the tensile strengths of samples 1# and 2# are not obviously enhanced due to the weak bonding strength between SiC fiber and Ti, while those of sample 3# are achieved above 90% of ROM (the rule of mixtures) strength because of excellent bonding between SiC fiber and Ti. However, there are distinct Ti/Cu interfacial reaction zones after the three processes, which are approximately 5.4, 9.0 and 13.3 μm thick, respectively. The Ti/Cu interfacial reaction products are mainly distributed in four layers. In samples 1# and 2#, the products are predicted to be Cu 4 Ti, Cu 3 Ti 2 , CuTi and CuTi 2 according to their chemical compositions determined by EDS, while in sample 3#, the products are Cu 4 Ti, Cu 4 Ti 3 , CuTi and CuTi 2 . Additionally, the relationships between the thickness of Ti interlayer and its reaction with C and Cu are also discussed, and an optimal thickness of Ti is introduced.

By using Monte Carlo simulation, adsorption of both end-adsorbed and middle-adsorbed symmetric triblock copolymers from a non-selective solvent on an impenetrable surface has been studied. Influences of the adsorption energy, the bulk concentration, the chain composition and the chain length on the adsorption behavior including the surface coverage, the adsorption amount and the layer thickness are presented. It is shown that the total surface coverage for both end-adsorbed and middle-adsorbed copolymers increases monotonically as the bulk concentration increases. The higher the adsorption energy and the more the attractive segments, the higher the total surface coverage is exhibited. Surface coverage θ decreases with increasing the length of the non-attractive segments, but the product of θ and the proportion of the non-attractive segments in a triblock copolymer chain is nearly independent of the chain length. The adsorption amount increases almost monotonically with the bulk concentration. The logarithm of the adsorption amount is a linear function of the reciprocal of the reduced temperature. When the adsorption energy is large, the adsorption amount exhibits a maximum as the composition of the attractive segment increases. The adsorption isotherms of copolymers with different length of the non-attractive segments can be mapped onto a single curve under certain energy indicating that copolymers with different chain length have the same adsorption amount. The adsorption layer thickness for the end-adsorbed copolymers decreases as the energy and the number of adsorbing segments increases. The longer non-attractive segments, the larger adsorbed layer thickness is found. The tails mainly governs the adsorption layer thickness.

Monte Carlo simulations for the adsorption of symmetric triblock copolymers from a nonselective solvent at a solid–liquid interface have been performed on a lattice model. In simulations, triblock copolymer molecules are modeled as self-avoiding linear chains composed of m segments of A and n segments of B arranged as A m /2 B n A m /2 . Either segment A or segment B is attractive, while the other is non-attractive to the surface. The microstructure of the adsorbed layers, including the segment-density profiles and the size distribution of loops, tails and trains are presented. The effect of the adsorption energy, the bulk concentration, the chain composition, as well as the chain length on various adsorption properties has been studied. The results have shown that the size distribution of various configurations is dependent of the adsorption energy, the chain composition and the chain length. The mean length of the loops, trains and tails is insensitive to the bulk concentration. The mean length of the trains increases and that of the tails decreases as the adsorption energy and the length of the attractive segments increase. The mean length of the loops for the end-adsorbed copolymers appears a maximum and that for middle-adsorbed copolymers appears a minimum as the length of attractive segments increases. The length of the non-attractive segments affects mostly the size distribution of the tails. The longer the chain is, the larger the tail appears. The mean length of the tails and loops increases linearly as the length of the non-attractive segments increases, but that of the trains approximately is unchanged.

A new and rapid heat-treatment process for fabricating lead zirconate titanate, Pb(Zr 0.52 Ti 0.48 )O 3 (PZT), ferroelectric thin films has been developed. The main equipment of this heat-treatment process is termed caterpillar furnace. The furnace is divided into three parts, including preheating, heating and cooling. This process offers several advantages over conventional thermal annealing, including rapid heat-treatment process (< 10 min every layer film), pure film structure and better reproducibility. The precursor solution was synthesized by mixing and reacting lead acetate trihydrate, titanium isopropoxide, tetrabutyl zirconate, acetylacetone and 2-methoxyethanol. The precursor was investigated by DSC-TG, and the PZT thin film was investigated by XRD. XRD analysis shows that the thin films possess single-phase perovskite-type structure. A dielectric constant and loss tangent of thin film were measured about 231 and 0.02 at 10 kHz, respectively. The capacitance-voltage (C-V) and hysteresis loops of PZT films showed that the films possess fine ferroelectric properties.

By using sol-gel method, ferroelectric Pb(Zr 0.5 Ti 0.5 )O 3 (PZT) thin film with PbTiO 3 (PT) buffer layers are deposited on Pt/Ti/SiO 2 /Si substrates to investigate the effect of PT buffer layers on the microstructure and properties of PZT thin films. PT layers are served as interfacial layers between Pt and PZT thin films. After annealing at 600°C for 1 h, the thickness of PZT/PT multilayer film is about 650nm. The microstructure of the thin films has been investigated by X-ray diffraction (XRD). Dielectric properties and leakage current are determined by HP4284A LCR meter and Keithley 6517A picoameter. Experiment results show that PT buffer layer is helpful to decrease the annealing temperature of PZT thin film. After annealed at 600°C, PZT/PT multilayer thin films can get perovskite structure, while PZT thin films without PT buffer layer annealed at 600 °C, a second phase appears. PT buffer layer can also improve the dielectric properties of PZT thin film. The dielectric constant and the dielectric loss of PZT/PT multilayer thin films are lower than those of the pure PZT thin films.