Biography:

In the past Long Li has collaborated on articles with He Mincai and Jianzhuang Xiao. One of their most recent publications is Injection phototransistors. Which was published in journal Sensors and Actuators A: Physical.

More information about Long Li research including statistics on their citations can be found on their Copernicus Academic profile page.

Long Li's Articles: (90)

Injection phototransistors

AbstractThe photoelectronic characteristics of an injection phototransistor are analysed by the concept of indirect coupling photodetection; the characteristic curves of the device are measured and explaned. The photo-dark-current ratio and the photoelectronic response time of the injection phototransistor are compared with those of a conventional phototransistor, both devices being based on a common illuminated PN junction.

Compressive behaviour of recycled aggregate concrete under impact loading

AbstractThe compressive behaviour of recycled aggregate concrete (RAC) with different recycled coarse aggregate (RCA) replacement percentages was experimentally investigated under quasi-static to high strain rate loading. Quasi-static tests at a strain rate of 10− 5/s were first carried out using a stiff-framed servo-hydraulic machine. Impacting tests at strain rates ranging from 101/s to 102/s were then performed using a 74 mm-diameter Split Hopkinson Pressure Bar (SHPB) facility. The strain rate effects on the failure pattern, compressive strength, initial elastic modulus and peak strain were studied. The results showed that the compressive strength and initial elastic modulus increased with increasing strain rate while the peak strain did not display clear strain rate dependence. At high strain rates the compressive strength decreased with increasing RCA replacement percentage, whereas the dynamic increase factor (DIF) showed a reverse tendency. Furthermore, the dynamic compressive strength of wet RAC was lower than that of naturally dried RAC.

Isotope-ratio-monitoring gas chromatography methods for high-precision isotopic analysis of nanomole quantities of silicate nitrogen

AbstractWe have developed a system for analyzing nanomole-sized quantities of silicate-derived N2 by carrier-gas methods, through combination of a metal high-vacuum extraction line fabricated at Lehigh University and a commercially available continuous-flow, gas chromatography interface (the Finnigan Gas Bench II). This work involves heating of samples to 950–1050 °C (depending on the material being analyzed), with Cu metal and Cu oxide reagents, in evacuated and sealed 6 mm (o.d.) quartz tubes. Uncertainties (expressed as 1σ for ≥ 3 replicate analyses of both internal silicate standards and unknowns) are generally less than 5% for N concentrations and on the order of 0.15‰ δ15N for samples with > 5 ppm N. At current blank levels (minimum overall system blank of 3.8 ± 0.2 nmol N2 with a δ15Nair value of − 7.3 ± 0.4‰, mean ± 1σ), uncertainty in δ15N increases to ∼ 0.6‰ for samples with 1–2 ppm N. Practical minimum sample size, taking into account blanks and other factors affecting N2 transfer, is now ∼ 10 nmol, two orders of magnitude smaller than that previously possible in our laboratory using dual-inlet microvolume methods (∼ 1 μmol). These methods, which can be employed in any laboratory able to undertake continuous flow techniques (with a dynamic-vacuum, isotope ratio mass spectrometer), afford increased spatial resolution in some studies and open up many new avenues of investigation previously impeded by the absence of sufficiently N-rich materials.

Tree-ring width and δ13C records of industrial stress and recovery in Pennsylvania and New Jersey forests: Implications for CO2 uptake by temperate forests

AbstractWe present dendrochronological records of tree-ring width and δ13C values for representative living trees (ages of 70 to 230 years) in Pennsylvania and New Jersey to investigate the ecological responses to industrial pollution and recent management and their effects on carbon storage in the temperate forests. Chestnut oak, red oak and cedar trees consistently show elevated δ13C levels (1.3 to 4.1‰ higher than unpolluted normal values) during the period of intense pollution from ∼ 1900 to ∼ 1970, indicating significant industrially induced physiological stress on the trees. Since ∼ 1970, oak and cedar trees have shown remarkable increase in growth rates and rapid decrease of 0.6 to 2.5‰ in δ13C values, indicating the recovery of trees corresponding to the implementation of the Clean Air Act in the early 1970s. The growth enhancement since 1970 has resulted in an increase in biomass of ∼ 26% in cedar trees and ∼ 66% in oak trees, suggesting that air-cleaning efforts have made a significant contribution to CO2 uptake by the temperate forests, at least in the northeastern USA.

Anomalous nitrogen isotopes in ultrahigh-pressure metamorphic rocks from the Sulu orogenic belt: Effect of abiotic nitrogen reduction during fluid–rock interaction

Highlights•Nitrogen isotope compositions of metamorphic rocks subducted to >120–200 km.•Anomalously low N isotope composition as low as −15.8‰.•A possible record of abiotic N reduction process in fossil continental hydrothermal system.

Diamond isotope compositions indicate altered igneous oceanic crust dominates deep carbon recycling

Highlights•AOC contains carbonate with extremely variable δ13C values from −24‰ to +11‰.•An input flux of 1.5 × 1012 mol C/yr is contributed by AOC into global trench.•This amount is comparable to C input flux by sediment into global trench.•Recycling of AOC solely well explains C-N isotopic feature of eclogitic diamond.•AOC, rather than sediment, is the key carrier for C recycling into the deep mantle.

Sensitive origami dual-analyte electrochemical immunodevice based on polyaniline/Au-paper electrode and multi-labeled 3D graphene sheets

Highlights•A microfluidic origami multianalyte electrochemical immunodevice was fabricated.•Polyaniline-AuNPs modified paper working electrodes were used as sensor platform.•3DGS were used as matrices to immobilize the redox probes and antibodies.

Complex trajectories of aquatic and terrestrial ecosystem shifts caused by multiple human-induced environmental stresses

AbstractLarge shifts in the isotopic compositions of organic matter (OM) in lake sediments, over the last few hundred years, are commonly interpreted as representing changes in photosynthetic productivity corresponding to eutrophication or in the input of terrestrial OM due to human disturbances. Based on multiple-proxy data (C:N ratio, δ13C and δ15N of OM, δ13C of calcite, lithology and fossil pollen) from a 700-year sediment core at White Lake, New Jersey (USA), we propose a new explanation that relates these large shifts in OM δ13C and δ15N to human-induced changes in aquatic OM producers. Combined records of geochronology, fossil pollen and lithology from White Lake reveal that the upland forest was cleared by European settlers for farmland beginning around 1745 A.D. and has gradually reforested since 1930 after the abandonment of the farmlands. For the pre-agricultural period, OM had relatively constant but extremely low δ13CVPDB (−35.8 to −34.5‰) and δ15NAir (−3.5 to −2.5‰) and high atomic C:N ratios (13.7 to 16.7), indicating a stable anoxic lake environment with prominent microbial producers. Following the human disturbance (since 1745), high OM mass accumulation rates and abundances of the green alga Pediastrum indicate an increase in aquatic photosynthetic productivity due to enhanced nutrient input from disturbed uplands. However, carbonate δ13C remains constant or even decreases during this period, implying that increasing productivity did not elevate the δ13C of dissolved inorganic carbon and thus cannot explain the observed large increase in OM δ13C (7.4‰) and δ15N (5.8‰) over this period. Instead, δ13C, δ15N and C:N ratios of OM and differences in δ13C between calcite and OM suggest that the large increase in OM δ13C and δ15N can be attributed to a human-induced ecological shift in the predominant organic source from anaerobic bacteria to autotrophic phytoplankton. During the post-agricultural period, mass accumulation rates of OM, carbonate and silicate, and the δ13C of OM and calcite all decreased significantly, corresponding to stabilization of the uplands. However, over the last 70 years, an intensifying aquatic stress from the deposition of 15N-enriched industrial pollutants has resulted in a steady increase of 1.9‰ in δ15N. Proxy records for lake (δ13C and δ15N of OM) and upland conditions (pollen and silicates) at White Lake show complex trajectories of the aquatic and terrestrial ecosystems in response to past human disturbances.

Nitrogen geochemistry as a tracer of fluid flow in a hydrothermal vent complex in the Karoo Basin, South Africa

AbstractWe have investigated the N geochemistry of minerals and rocks from contact metamorphic aureoles and hydrothermal vent complexes (HVC) in the Karoo Basin in South Africa. The HVC formed during phreatic eruptions associated with rapid devolatilization and pressure build-up in contact aureoles around early Jurassic sill intrusions. By combining outcrop data from a HVC and core data from contact aureoles, we investigate the relationship between light element release during metamorphism and vertical fluid migration. Sandstone and breccia from the HVC contain early-diagenetic ammonium NH4+-bearing feldspar (buddingtonite) and illite. Ammonium occupies up to 95% of the A site in feldspar, corresponding to concentrations up to 5.2 wt% N. Bulk-rock N isotope data for rocks from inside and outside the hydrothermal vent complex fall into two distinct groups. Background samples have δ15Nair between +1.5‰ and +4.9‰, whereas minerals from the vent complex have δ15N in the range +7.5 to +10.6‰. The N geochemistry of contact metamorphic shale from the lower stratigraphic units of the Karoo Basin shows that the vitrinite reflectance and δ15N values are positively correlated. Shale with reflectivity values >4%Ro are enriched in 15N, with δ15N values between +6‰ and +14‰, implying the release of isotopically light N into metamorphic fluids (probably as N2). We suggest that the relatively high δ15N values of the early-diagenetic buddingtonite in the HVC reflect exchange of buddingtonite with N-bearing fluids ascending from greater depth after their release during contact metamorphism and dehydration. We present a qualitative model whereby hydrothermal vent complexes represent fluid flow structures after their formation, focusing N-bearing metamorphic fluids sourced in deeper levels of the basin. The release of organic N from sediments at depth in volcanic basins could play a role in the geochemical cycle of N, becoming particularly important during periods of intense volcanic activity.

Ammonium stability and nitrogen isotope fractionations for NH4+–NH3(aq)–NH3(gas) systems at 20–70 °C and pH of 2–13: Applications to habitability and nitrogen cycling in low-temperature hydrothermal systems

AbstractAmmonium/ammonia is an essential nutrient and energy source to support life in oceanic and terrestrial hydrothermal systems. Thus the stability of ammonium is crucial to determine the habitability or ecological structure in hydrothermal environments, but still not well understood. To date, the lack of constraints on nitrogen isotope fractionations between ammonium and ammonia has limited the application of nitrogen isotopes to trace (bio)geochemical processes in such environments. In this study, we carried out laboratory experiments to (1) examine the stability of ammonium in an ammonium sulfate solution under temperature conditions from 20 to 70 °C and pH from 2.1 to 12.6 and (2) determine nitrogen isotope fractionation between ammonium and ammonia.Our experimental results show that ammonium is stable under the experimental temperatures when pH is less than 6. In experiments with starting pH greater than 8, significant ammonium was lost as a result of dissociation of ammonium and degassing of ammonia product. Nitrogen concentrations in the fluids decreased by more than 50% in the first two hours, indicating extremely fast effusion rates of ammonia. This implies that ammonium at high pH fluids (e.g., Lost City Hydrothermal Vents, Oman ophiolite hyperalkaline springs) may not be stable. Habitable environments may be more favorable at the leading edge of a pH gradient toward more acidic conditions, where the fluid can efficiently trap any ammonia transferred from a high pH vent. Although modeling shows that high temperature, low pH hydrothermal vents (e.g., Rainbow hydrothermal vent) may have the capability to retain ammonium, their high temperatures may limit habitability. The habitable zone associated with such a hydrothermal vent is likely at the lower front of a temperature gradient. In contrast, modeling of ammonium in deep terrestrial systems, suggests that saline fracture waters in crystalline rocks such as described in the Canadian Shield and in the Witwatersrand Basin, South Africa may also provide habitable environments for life.The nitrogen isotope results of remaining ammonium from the partial dissociation experiments fit well with a batch equilibrium model, indicating equilibrium nitrogen isotope fractionations have been reached between ammonium and its dissociation product aqueous ammonia. Modeling yielded nitrogen isotope fractionations between ammonium and aqueous ammonia were 45.4‰ at 23 °C, 37.7‰ at 50 °C, and 33.5‰ at 70 °C, respectively. A relationship between nitrogen equilibrium isotope fractionation and temperature is determined for the experimental temperature range as:103·lnαNH4+-NH3(aq)=25.94×103T-42.25Integrated with three previous theoretical estimates on nitrogen isotope equilibrium fractionations between ammonium and gaseous ammonia, we achieved three possible temperature-dependent nitrogen isotope equilibrium fractionation between aqueous ammonia and gaseous ammonia:(1)103·lnαNH3(aq)-NH3(gas)=13.73×103T-30.76(2)103·lnαNH3(aq)-NH3(gas)=13.54×103T-30.51(3)103·lnαNH3(aq)-NH3(gas)=12.88×103T-36.00These calibrations provide a new tool to contribute to the study of nitrogen cycling under low temperature subsurface conditions.

Primary multiple sulfur isotopic compositions of pyrite in 2.7 Ga shales from the Joy Lake sequence (Superior Province) show felsic volcanic array-like signature

AbstractMultiple sulfur isotopes provide a powerful tool to study photochemical and biological processes controlling the Archean sulfur cycle and infer related atmospheric and marine environments. However, our understanding of early Earth’s environment remains limited by the availability of well-preserved geological samples, as most Archean sedimentary rocks have experienced some degree of metamorphic alteration. To evaluate sulfur isotopic behavior during post-depositional processes and elucidate the sulfur cycle at 2.7 Ga, we use high-resolution in situ analytical techniques (EPMA and SIMS) to determine elemental compositions and multiple sulfur isotopic compositions of large diagenetic pyrite nodules and fine-grained secondary pyrite disseminated in quartz veins (formed during a lower greenschist metamorphic event) in shales from the 2.7 Ga Joy Lake sequence in the southwest Superior Province. Results show that trace metals and sulfur in the secondary pyrite were derived from both metamorphic fluid and pre-existing diagenetic pyrite. Diagenetic pyrite nodules could have been partially dissolved by metamorphic fluid. But the surviving nodules show elemental and isotopic features different from those of the deduced metamorphic fluid endmember, suggesting the nodules were not geochemically altered by metamorphism, and thus preserve primary isotopic signatures acquired during diagenesis. The sulfur isotopic ratios of pyrite nodules show strong variations, with decreasing δ34S values and increasing Δ33S values from cores to rims. This negative Δ33S–δ34S relationship is different from the commonly observed ‘Archean reference line’ defined by most Archean pyrite data, but similar to the ‘felsic volcanic array’. Our observation provides a first possible case from 2.7 Ga, the age of peak crustal growth in the Archean, to support the hypothesis that photochemical pathways could be different under conditions of intense volcanic emission. This study also shows that high-resolution SIMS and EPMA analyses are a robust method for distinguishing primary geochemical signatures from post-depositional alteration, and thus may be used to evaluate the sulfur cycle in Archean sedimentary rocks with low-grade metamorphic overprints.

Study on the enthalpy of solution and enthalpy of dilution for the ionic liquid [C3mim][Val] (1-propyl-3-methylimidazolium valine)

AbstractA new amino acid ionic liquid (AAIL) [C3mim][Val] (1-propyl-3-methylimidazolium valine) was prepared by the neutralization method. Using the solution-reaction isoperibol calorimeter, molar solution enthalpies of the ionic liquid [C3mim][Val] with known amounts of water and with different concentrations in molality were measured at T = 298.15 K. In terms of standard addition method (SAM) and Archer’s method, the standard molar enthalpy of solution for [C3mim][Val] without water, ΔsHm∘ = (−55.7 ± 0.4) kJ · mol−1, was obtained. The hydration enthalpy of the cation [C3mim]+, ΔH+ ([C3mim]+) = −226 kJ · mol−1, was estimated in terms of Glasser’s theory. Using the RD496-III heat conduction microcalorimeter, the molar enthalpies of dilution, ΔDHm(mi → mf), of aqueous [C3mim][Val] with various values of molality were measured. The values of ΔDHm(mi → mf) were fitted to Pitzer’s ion-interaction model and the values of apparent relative molar enthalpy, φL, calculated using Pitzer’s ion-interaction model.

Regular ArticleA Schiff base/quaternary ammonium salt bifunctional graphene oxide as an efficient adsorbent for removal of Th(IV)/U(VI)

AbstractA novel approach for facile covalent functionalization of graphene oxide (GO) was proposed in the present study in order to effectively avoid necessary anhydrous conditions and the usage of harsh reagents during the chemical functionalization of GO. Herein, a GO derivative that was functionalized with a primary amine derivative bearing a positively charged quaternary ammonium group, GO-S, was synthesized through a Schiff base condensation reaction between the amine groups of the primary amine derivative and the aldehyde groups of GO. The introduction of the quaternary ammonium groups can prevent GO from stacking and improve the dispersibility of GO after modification. The formation of imine bonds (NCH) between the primary amine and GO has been confirmed by Fourier transform infrared and X-ray photoelectron spectroscopy. The GO-S demonstrated good dispersion stability in aqueous medium and also exhibited better adsorption performance than GO for Th(IV) and U(VI), with a maximum thorium adsorption capacity of 2.22 mmol/g and a maximum uranium adsorption capacity of 0.83 mmol/g, suggesting a great potential for the application of graphene oxide-based materials for facilitating the removal of Th(IV) and U(VI) from nuclear waste solutions.

Control of the growth mode of epitaxial c-axis YBa2Cu3O7−δ thin films by vicinal (0 0 1) SrTiO3 substrates

AbstractC-axis YBa2Cu3O7−δ (YBCO) thin films have been grown epitaxially in the step-flow mode with the increase of vicinal angle of the SrTiO3 substrates by pulsed laser deposition. However surface hollows/cracks occurred with increasing angle, which disrupted the smoothness of the film surfaces. By reducing the oxygenate pressure during the tetragonal–orthogonal structural phase transition, the YBCO films with smooth surface was formed, but the films are superconducting at 60 K. These films have good metallic property hence they can be employed as electrodes for ferroelectric heterostructures.

Review articleLymphatic system identification, pathophysiology and therapy in the cardiovascular diseases

Highlights•The new identification techniques have enhanced our current understanding of LVs.•The LVs play an important role in pathophysiological mechanisms of AS and MI.•Inducing lymphangiogenesis can bring therapeutically benefits for AS and MI.•Drug delivery and therapeutic potential of the LVs deserve increasing attention.

CommunicationsStructural Analysis and Optimization of the Covalent Association between SpyCatcher and a Peptide Tag☆

Highlights•SpyTag/SpyCatcher provides a unique covalent peptide-tagging system.•The crystal structure of SpyTag/SpyCatcher was determined at 2.1 Å resolution.•The structure predicts that the N- and C-termini of SpyCatcher are dispensable.•Biochemical experiments confirm the structural predictions.•The results lead to an optimized SpyTag/SpyCatcher system.

Ectopic distal location of the papilla of vater in congenital biliary dilatation: Implications for pathogenesis☆

AbstractBackground/Purpose: This study investigates the relationship between the location of the papilla of Vater and the length of the common channel in patients with congenital biliary dilatation (CBD). Methods: Cholangiograms from 121 CBD patients and 13 normal controls were the subjects for this study. A length index defined as the length of the common channel divided by the height of the second lumbar vertebra was used for standardization. Results: In the controls, the papilla of Vater was located in the middle of the descending or second part of the duodenum in all cases. In 39 (32.2%) of the 121 CBD patients papilla of Vater was located in the descending duodenum (group I), and in 82 (67.8%) it was distal to the descending duodenum (group II). The average length index of the common channel in group II was significantly longer than in group I (1.123 ± 0.374 v 0.660 ± 0.246; P < .001). Findings for the common bile duct were similar. Conclusions: There is a significantly higher incidence of ectopic distal location of the papilla of Vater in CBD patients than in controls. The more distal the location of the papilla of Vater, the longer the common bile duct and the common channel. J Pediatr Surg 36:1617-1622. Copyright © 2001 by W.B. Saunders Company.

Evolution of surgical paediatrics in China

AbstractPediatric surgery of China was established in 1950. Being isolated from the world, China’s first-generation pediatric surgeons were mainly self-taught. The technology of pediatric surgery of China practically followed Gross, and the aim of pediatric surgery was similar to that of BAPS, “not to seek a monopoly.” Since 1980, after the scientific exchange with Western countries, the clinical results of common pediatric surgical diseases have reached the acceptable level of the world. China is a huge country with poor transportation, one-child family planning, and Chinese traditional medicine, which made certain peculiarities in the practice of paediatric surgery.

Original articleLaparoscopic excision of choledochal cyst and Roux-en-Y hepaticojejunostomy in symptomatic neonates

AbstractPurposeCholedochal cysts require surgical excision, preferably before the onset of cholangitis. Recently, it has become feasible to accomplish the excision laparoscopically in adults and older children. Yet, whether laparoscopic excision of choledochal cyst can be performed safely in symptomatic neonates with choledochal cyst is unclear. We herewith reviewed our experience of laparoscopic excision of choledochal cysts in neonates.MethodsWe managed 9 neonates with choledochal cysts between April 2003 and February 2007. The choledochal cysts were excised laparoscopically. The Roux-en-Y hepaticojejunostomy was fashioned extracorporeally by exteriorizing the jejunum through the extended umbilical port site. End-to-side anastomosis between the common hepatic duct stump and Roux loop was carried out intracorporeally. The patients were followed up for an average of 26 months.ResultsThe patients presented with jaundice, pale stool, and deranged liver function tests. The diagnosis was confirmed with ultrasonography postnatally. The median operation time was 3.6 hours. There was no operative complication and no conversion. The blood loss was minimal. The recovery was uneventful, and the median hospital stay was 6 days. The liver function tests normalized 3 to 16 weeks postoperatively. No complication was detected at the follow-up visits.ConclusionsOur preliminary results show that laparoscopic excision of choledochal cyst and Roux-en-Y hepaticojejunostomy in neonates is both feasible and safe. It curtails further complication of the cysts and reverses the derangement of liver function. In addition, the laparoscopic approach minimizes surgical trauma.

Original articleThe effect of laparoscopic excision vs open excision in children with choledochal cyst: a midterm follow-up study☆☆☆

AbstractPurposeCyst excision with hepaticojejunostomy has been the classic procedure for treating choledochal cysts. Recently, laparoscopic treatment of the disease has gained popularity worldwide. The aim of this study is to evaluate whether laparoscopic management of choledochal cysts is as feasible and safe as conventional open surgery in children with this disease.MethodsA retrospective study comparing the laparoscopic and the open procedures was performed in 77 consecutive patients with choledochal cyst in our hospital. Thirty-nine patients operated on between June 2001 and September 2003 were in the laparoscopic group, whereas 38 patients in the open group were operated on between February 1999 and May 2001.ResultsPatient demographics were similar between the 2 groups. The duration of operation was significantly longer in the laparoscopic group than in the open group (median, 230 vs 190 minutes; P < .001). In contrast, the durations of delayed oral feeding and hospital stay postoperatively were significantly shorter in the laparoscopic group (median, 4 vs 5 days [P < .01] and median, 5 vs 7 days [P < .01], respectively.) There were no differences in the early and late complication rates between the 2 groups.ConclusionsLaparoscopic treatment of choledochal cyst in children is feasible and safe. For experienced centers, this procedure can be recommended.

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