Large Production Rates Research Articles

Continuous Synthesis of Nanocrystals via Flow Chemistry Technology.

Modern nanotechnologies bring humanity to a new age, and advanced methods for preparing functional nanocrystals are cornerstones. A considerable variety of nanomaterials has been created over the past decades, but few were prepared on the macro scale, even fewer making it to the stage of industrial production. The gap between academic research and engineering production is expected to be filled by flow chemistry technology, which relies on microreactors. Microreaction devices and technologies for synthesizing different kinds of nanocrystals are discussed from an engineering point of view. The advantages of microreactors, the important features of flow chemistry systems, and methods to apply them in the syntheses of salt, oxide, metal, alloy, and quantum dot nanomaterials are summarized. To further exhibit the scaling-up of nanocrystal synthesis, recent reports on using microreactors with gram per hour and larger production rates are highlighted. Finally, an industrial example for preparing 10 tons of CaCO3 nanoparticles per day is introduced, which shows the great potential for flow chemistry processes to transfer lab research to industry.

Mathematical study of spray flash evaporation in a spray-assisted seawater desalination chamber

Spray flash evaporation is a method for the new desalination technology driven by renewable energy. This paper studies the flash evaporation phenomenon of the seawater jet sprayed into a low-pressure chamber. A droplet flash evaporation model has been developed to enable an in-depth understanding of the flash evaporation. This model is capable of predicting the spray flash speed, the evaporated mass rate and the flashing efficiency under different working conditions. Applying this model, the effects of different operating variables on the flash evaporation process are investigated. Results from the developed model reveal a larger Jakob number, Reynolds number and Weber number all lead to the increase of the production rate. The flashing efficiency can attain values larger than 0.9 with the nozzle diameter ranging 5–14 mm when the flash chamber is 150 mm height. The flashing efficiency with nozzle diameter of 5 mm is larger than 0.9 when the flash chamber is 25 mm height. The flow velocity of 10 m/s is recommended for the current case to obtain a large production rate. A flash chamber larger than 500 mm height is needed for complete evaporation considering the presence of dissolved salt in sea water.

Constraining four-fermion operators using rare top decays

New physics can manifest itself by an appreciable increase of the decay rate of top quarks in rare flavour-changing final states. Exploiting the large top quark production rate at the LHC, we bound four-fermion operators contributing to non-resonant t → ℓ+ℓ−j using different signal regions of the latest LHC searches for t → Zj. We also provide prospects for the high-luminosity LHC to test these as well as four-fermion operators contributing to tto boverline{b}j , based on improved analysis strategies of existing searches. We single out all weakly-coupled ultraviolet completions inducing such contact interactions at tree level and translate the previous bounds to the parameter space of specific complete models. Being above the TeV, LHC bounds from rare top decays improve over those from flavour physics, electroweak precision data and other LHC searches in several cases.

System response to gas production from a heterogeneous hydrate accumulation at the UBGH2-6 site of the Ulleung basin in the Korean East Sea

We investigate the feasibility of production from a layered marine gas hydrate reservoir using the properties and conditions corresponding to the UBGH2-6 site of the Ulleung Basin in the Korean East Sea. The work expands and furthers previous investigations in support of a proposed field test. The target system is location in deep water and consists of 13 m of alternating hydrate-bearing sand and soft mud layers and will be produced using a vertical well. We assess production potential during a 14-day field test, examine sensitivity to heterogeneity in permeability, porosity, and initial hydrate saturation, and assess the geomechanical response of the system to short-term production. Producing gas from the system appears to be technically feasible, however, low production rates and relatively large water production rates are expected during the field test. Expected subsidence and reservoir compaction is limited given the current data and the short timeframes of the production test.

Production of Z_c(3900) and Z_c(4020) in B_c decay

In the present work, we propose to search the charmonium-like states Z_c(3900) and Z_c(4020) in the B_c decay. In an effective Lagrangian approach, the branching ratios of B_c^+ rightarrow Z_c(3900)^+ pi ^0 and B_c^+rightarrow Z_c (4020)^+ pi ^0 are estimated to be of order of 10^{-4} and 10^{-7}, respectively. The large production rate of Z_c(3900) could provide an important source of the production of Z_c(3900) from the semi-exclusive decay of b-flavored hadrons reported by D0 Collaboration, which can be tested by the exclusive measurements in LHCb.

Two Bulky Conjugated 4′‐(4‐Hydroxyphenyl)‐4,2′:6′,4′′‐terpyridine‐based Layered Complexes: Synthesis, Structure, and Photocatalytic Hydrogen Evolution Activity

Two new layered complexes with the formulas of {[Cu(H2O)(HL)2Cl](NO3)}n (1) and {[Cu(H2O)2(HL)2](NO3)2}n (2) were solvothermally synthesized by the reactions of the bulky conjugated 4′‐(4‐hydroxyphenyl)‐4,2′:6′,4′′‐terpyridine ligand (HL) with different CuII salts, which were further used as photocatalysts to achieve hydrogen production from water splitting. Single‐crystal structural analyses reveal that both complexes feature coplanar (4 4) layers with different connection manners between the HL extended Z‐shaped chains. More interestingly, 1 possessing more negative conduction band potential and higher structural stability exhibits a large hydrogen production rate of 2.43 mmol·g–1·h–1, which is four times higher than that of 2. Thus, the CuII‐based coordination polymers modified by the bulky conjugated organic ligand can become potentially promising non‐Pt photocatalysts for hydrogen production from water splitting.

Consistency of Higgsplosion in localizable QFT

We show that large n-particle production rates derived in the semiclassical Higgsplosion limit of scalar field theoretical models with spontaneous symmetry breaking, are consistent with general principles of localizable quantum field theory.The strict localizability criteria of Jaffe defines quantum fields as operator-valued distributions acting on test functions that are localized in finite regions of space–time. The requirement of finite support of test functions in space–time ensures the causality property of QFT. The corresponding localizable fields need not be tempered distributions, and they fit well into the framework of local quantum field theory.

The false positive effect of residue of sulphur sources on dithiocarbamate analysis based on CS2 measurement

ABSTRACTTurkey plays an important role in the international trade of apricots as it has the largest production rate in the world. Since the sulphurisation process is allowed to be used for different products, the effect of residual sulphur and its compounds (which can be found in products as pesticide residues or additive residues) on the positive detection of carbon disulphide (CS2) still creates a big challenge in international trade. Therefore, the main objective of the present study was to investigate the effects of residues of sulphur or sulphur compounds on dithiocarbamate analysis methods based on CS2 measurement. In this study, apricots were chosen since they contain sulphur residues as a result of the sulphurisation process. Sulphur dioxide and dithiocarbamate analyses were conducted on dried apricots prepared with the sulphurisation process (SA) and without the sulphurisation process (NSA); analysis was by two different accredited laboratories. No of pesticide was applied to either SA or NSA samples. Although some of the NSA samples had <LOQ values, approximately 70 ± 32 mg/kg SO2 and 0.061 ± 0.021 mg/kg dithiocarbamate were detected for NSA samples. On the other hand, for the SA sample group, 927–2915 mg/kg of SO2 and 0.265–0.825 mg/kg of dithiocarbamate were detected. Furthermore, a strong correlation between residual sulphur and dithiocarbamate values was observed. This study showed that the analysis method based on CS2 measurement may lead to false positive results for dithiocarbamates when residues of sulphur or sulphur compounds are found in products as pesticide or additive residues. Therefore, residual sulphur compounds as a result of the sulphurisation process (which is not considered during the evaluation of products) must be taken into account during the evaluation of products for dithiocarbamates.

Limits on electroweak instanton-induced processes with multiple boson production

Recently, the CMS collaboration has reported their search for electroweak instanton-like processes with anomalous B + L violation assuming multi-fermion but zero-boson final states. On the other hand, many theoretical studies suggest that anomalous B + L processes may have an observably large production rate only if their final state contains a large number of electroweak gauge bosons. In this paper, we review the state-of-the-art of the predictions of electroweak instanton-induced processes and compare collider signatures of zero- and multi-boson events of anomalous B + L violation at the LHC. An upper limit on the cross-section for the multi-boson process is derived by recasting the CMS analysis.

Field measurements of methylglyoxal using proton transfer reaction time-of-flight mass spectrometry and comparison to the DNPH–HPLC–UV method

Abstract. Methylglyoxal (MGLY) is an important atmospheric α-dicarbonyl species for which photolysis acts as a significant source of peroxy radicals, contributing to the oxidizing capacity of the atmosphere and, as such, the formation of secondary pollutants such as organic aerosols and ozone. However, despite its importance, only a few techniques exhibit time resolutions and detection limits that are suitable for atmospheric measurements. This study presents the first field measurements of MGLY by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) performed during the ChArMEx SOP2 field campaign. This campaign took place at a Mediterranean site characterized by intense biogenic emissions and low levels of anthropogenic trace gases. Concomitant measurements of MGLY were performed using the 2,4-dinitrophenylhydrazine (DNPH) derivatization technique and high performance liquid chromatography (HPLC) with UV detection. PTR-ToF-MS and DNPH–HPLC measurements were compared to determine whether these techniques can perform reliable measurements of MGLY. Ambient time series revealed levels of MGLY ranging from 28 to 365 pptv, with a clear diurnal cycle due to elevated concentrations of primary biogenic species during the daytime, and its oxidation led to large production rates of MGLY. A scatter plot of the PTR-ToF-MS and DNPH–HPLC measurements indicates a reasonable correlation (R2=0.48) but a slope significantly lower than unity (0.58±0.05) and a significant intercept of 88.3±8.0 pptv. A careful investigation of the differences between the two techniques suggests that this disagreement is not due to spectrometric interferences from H3O+(H2O)3 or methyl ethyl ketone (or butanal) detected at m∕z 73.050 and m∕z 73.065, respectively, which are close to the MGLY m∕z of 73.029. The differences are more likely due to uncorrected sampling artifacts such as overestimated collection efficiency or loss of MGLY into the sampling line for the DNPH–HPLC technique or unknown isobaric interfering compounds such as acrylic acid and propanediol for the PTR-ToF-MS. Calculations of MGLY loss rates with respect to OH oxidation and direct photolysis indicate similar contributions for these two loss pathways.

New physics opportunities for long-lived particles at electron-proton colliders

Future electron-proton collider proposals like the LHeC or the FCC-eh can supply ab−1 of collisions with a center-of-mass energy in the TeV range, while maintaining a clean experimental environment more commonly associated with lepton colliders. We point out that this makes e−p colliders ideally suited to probe BSM signatures with final states that look like “hadronic noise” in the high-energy, pile-up-rich environment of pp colliders. We focus on the generic vector boson fusion production mechanism, which is available for all BSM particles with electroweak charges at mass scales far above the reach of most lepton colliders. This is in contrast to previous BSM studies at these machines, which focused on BSM processes with large production rates from the asymmetric initial state. We propose to exploit the unique experimental environment in the search for long-lived particle signals arising from Higgsinos or exotic Higgs decays. At e−p colliders, the soft decay products of long-lived Higgsino can be explicitly reconstructed (“displaced single pion”), and very short lifetimes can be probed. We find that e−p colliders can explore significant regions of BSM parameter space inaccessible to other collider searches, with important implications for the design of such machines.

Enhanced di-Higgs boson production in the complex Higgs singlet model

We consider the Standard Model extended by the addition of a complex scalar singlet, with no assumptions about additional symmetries of the potential. This model provides for resonant di-Higgs production of Higgs particles with different masses. We demonstrate that regions of parameter space allowed by precision electroweak measurements, experimental limits on single Higgs production, and perturbative unitarity allow for large di-Higgs production rates relative to the SM rates. In this scenario, the dominant production mechanism of the new scalar states is di-Higgs production. Results are presented for $\sqrt{S}=13$, $27$ and $100~TeV$.

Numerical investigation of the efficiency of emission reduction and heat extraction in a sedimentary geothermal reservoir: a case study of the Daming geothermal field in China.

The utilization of geothermal energy is clean and has great potential worldwide, and it is important to utilize geothermal energy in a sustainable manner. Mathematical modeling studies of geothermal reservoirs are important as they evaluate and quantify the complex multi-physical effects in geothermal reservoirs. However, previous modeling efforts lack the study focusing on the emission reduction efficiency and the deformation at geothermal wellbores caused by geothermal water extraction/circulation. Emission efficiency is rather relevant in geothermal projects introduced in areas characterized by elevated air pollution where the utilization of geothermal energy is as an alternative to burning fossil fuels. Deformation at geothermal wellbores is also relevant as significant deformation caused by water extraction can lead to geothermal wellbore instability and can consequently decrease the effectiveness of the heat extraction process in geothermal wells. In this study, the efficiency of emission reduction and heat extraction in a sedimentary geothermal reservoir in Daming County, China, are numerically investigated based on a coupled multi-physical model. Relationships between the efficiency of emission reduction and heat extraction, deformation at geothermal well locations, and geothermal field parameters including well spacing, heat production rate, re-injection temperature, rock stiffness, and geothermal well placement patterns are analyzed. Results show that, although large heat production rates and low re-injection temperatures can lead to decreased heat production in the last 8years of heat extraction, they still improve the overall heat production capacity and emission reduction capacity. Also, the emission reduction capacity is positively correlated with the heat production capacity. Deformation at geothermal wellbore locations is alleviated by smaller well spacing, lower heat production rates, and smaller numbers of injectors in the well pattern, and by placing wells at locations with higher rock stiffness. Compared with the reference case with coal burning for heating purposes, the yearly emission reduction capacity can reach 1 × 107kg by switching to the direct utilization of geothermal energy in Daming field.

Neutral meson production in Cu+Au collisions at 200 GeV

Strongly interacting quark-gluon plasma (sQGP) was discovered in central heavy ion collisions at RHIC energies. Jet quenching is one of the sQGP evidence observed in particle yields suppression related to yields measured in elementary nucleon-nucleon collisions. System of Cu+Au collisions is characterized by special nuclear overlap geometry different to other large systems (such as Au+Au). Study of such collision systems will help to estimate sQGP properties with higher accuracy. Neutral mesons such as π0 give a good opportunity for studying sQGP effects especially jet quenching due to their large production rate. This paper presents results on neutral pion invariant differential spectra and nuclear modification factors measured with PHENIX experiment.

Silicon Nanoparticles/Carbon Composites as Anodes for High-performance Lithium-ion Batteries

Silicon has emerged as the most promising anode candidate for next-generation lithium-ion batteries (LIBs) owing to its high theoretical specific capacity of 3579 mAh/g combined with a relatively low working potential and its natural abundance. However, the practical application of pristine Si in anodes is seriously hindered by its low intrinsic electrical conductivity and the large volume variation during charging and discharging. The resulting mechanical stress causes rapid pulverization of the silicon, and isolation and disconnection of the active materials from the current collector. These failure events mostly cause a rapid degeneration of the Si electrodes. In this study, Si nanoparticles (Si-NPs) were synthesized in a hot-wall reactor using monosilane as precursor. This process enables producing high purity Si NPs with a large production rate of up to 1 kg/h. Particle size, morphology, and crystallinity of the Si-NPs can be tuned towards optimized properties for battery applications by adjusting the synthesis parameters. In order to overcome the above mentioned failure scenarios of Si-NP-based anodes, Si/carbon nanocomposites such as Si-CNT, Si/graphene, Si-CNT/porous carbon, and Si-CNT/graphene composites have been developed to improve mechanical as well as electrical properties. As a highly promising product, the Si-CNT/ graphene nano-heterostructure demonstrates a high reversible initial capacity of 1665 mAh/g and very stable cycling performance over 500 cycles with a capacity decay of only 0.02% per cycle. Besides, the composite exhibits also a high-rate capability of 755 mAh/g (45.3% retention) at 10 C. These superior results imply that Si/carbon nano-heterostructures can be used for the development of high-performance lithium-ion batteries for durable and high-rate uses.

The structure and budget of turbulent kinetic energy in front of a wall-mounted cylinder

We investigate the flow and turbulence structure in front of a cylinder mounted on a flat plate by a combined study using highly resolved large-eddy simulation and particle image velocimetry. The Reynolds number based on the bulk velocity and cylinder diameter is $Re_{D}=39\,000$. As the cylinder is placed in an open channel, we take special care to simulate open-channel flow as the inflow condition, including secondary flows that match the inflow in the experiment. Due to the high numerical resolution, subgrid contributions to the Reynolds stresses are negligible and the modelled dissipation plays a minor role in major parts of the flow field. The accordance of the experimental and numerical results is good. The shear in the approach flow creates a vertical pressure gradient, inducing a downflow in the cylinder front. This downflow, when deflected in the upstream direction at the bottom plate, gives rise to a so-called horseshoe vortex system. The most upstream point of flow reversal at the wall is found to be a stagnation point which appears as a sink instead of a separation point in the symmetry plane in front of the cylinder. The wall shear stress is largest between the main (horseshoe) vortex and the cylinder, and seems to be mainly governed by the strong downflow in front of the cylinder as turbulent stresses are small in this region. Due to a strong acceleration along the streamlines, a region of relatively small turbulent kinetic energy is found between the horseshoe vortex and the cylinder. When passing under the horseshoe vortex, the upstream-directed jet formed by the deflected downflow undergoes a deceleration which gives rise to a strong production of turbulent kinetic energy. We find that pressure transport of turbulent kinetic energy is important for the initiation of the large production rates by increasing the turbulence level in the upstream jet near the wall. The distribution of the dissipation of turbulent kinetic energy is similar to that of the turbulent kinetic energy. Large values of dissipation occur around the centre of the horseshoe vortex and near the wall in the region where the jet decelerates. While the small scales are nearly isotropic in the horseshoe vortex centre, they are anistotropic near the wall. This can be explained by a vertical flapping of the upstream-directed jet. The distribution and level of dissipation, turbulent and pressure transport of turbulent kinetic energy are of crucial interest to turbulence modelling in the Reynolds-averaged context. To the best of our knowledge, this is the first time that these terms have been documented in this kind of flow.

Moisture statistics in free convective boundary layers growing into linearly stratified atmospheres

We use dimensional analysis and direct numerical simulations to characterize specific humidity statistics in the equilibrium (quasi‐steady) entrainment regime of cloud‐free convective boundary layers that grow into linearly stratified free atmospheres. The first three moments and the mean vertical flux are studied for arbitrary combinations of free‐atmosphere lapse‐rates and surface fluxes of buoyancy and specific humidity. First, we find the combination of these parameters that distinguishes between the entrainment‐drying regime and the surface‐moistening regime. We also provide a zero‐order model describing both regimes. Second, we parametrize the variances in the mixed layer and in the entrainment zone separately, based on convective and entrainment‐zone scales, respectively. We show that the large variances in the entrainment zone are not only due to large production rates, but also due to low dissipation rates. Third, we provide the skewness for any regime between the pure drying limit and the pure moistening limit. The variation of the skewness indicates that knowing the sign of the skewness near the surface is often insufficient to distinguish between drying and moistening regimes, in contrast to previous conjectures. In a more general context, this paper further supports the applicability of direct numerical simulations to investigate the atmospheric boundary layer, as inferred from the degree of Reynolds number similarity observed in the results and from the consistency of the derived parametrizations with field measurements.

Biochemical, hydrological and mechanical behaviors of high food waste content MSW landfill: Liquid-gas interactions observed from a large-scale experiment

The high food waste content (HFWC) MSW at a landfill has the characteristics of rapid hydrolysis process, large leachate production rate and fast gas generation. The liquid-gas interactions at HFWC-MSW landfills are prominent and complex, and still remain significant challenges. This paper focuses on the liquid-gas interactions of HFWC-MSW observed from a large-scale bioreactor landfill experiment (5m×5m×7.5m). Based on the connected and quantitative analyses on the experimental observations, the following findings were obtained: (1) The high leachate level observed at Chinese landfills was attributed to the combined contribution from the great quantity of self-released leachate, waste compression and gas entrapped underwater. The contribution from gas entrapped underwater was estimated to be 21–28% of the total leachate level. (2) The gas entrapped underwater resulted in a reduction of hydraulic conductivity, decreasing by one order with an increase in gas content from 13% to 21%. (3) The “breakthrough value” in the gas accumulation zone was up to 11kPa greater than the pore liquid pressure. The increase of the breakthrough value was associated with the decrease of void porosity induced by surcharge loading. (4) The self-released leachate from HFWC-MSW was estimated to contribute to over 30% of the leachate production at landfills in Southern China. The drainage of leachate with a high organic loading in the rapid hydrolysis stage would lead to a loss of landfill gas (LFG) potential of 13%. Based on the above findings, an improved method considering the quantity of self-released leachate was proposed for the prediction of leachate production at HFWC-MSW landfills. In addition, a three-dimensional drainage system was proposed to drawdown the high leachate level and hence to improve the slope stability of a landfill, reduce the hydraulic head on a bottom liner and increase the collection efficiency for LFG.

Searching for Axionlike Particles with Ultraperipheral Heavy-Ion Collisions.

We show that ultraperipheral heavy-ion collisions at the Large Hadron Collider (LHC) can be used to search for axionlike particles with mass below 100GeV. The Z^{4} enhanced photon-photon luminosity from the ions provides a large exclusive production rate, with a signature of a resonant pair of back-to-back photons and no other activity in the detector. In addition, we present both new and updated limits from recasting multiphoton searches at LEP II and the LHC, which are more stringent than those currently in the literature for the mass range 100MeV to 100GeV.

Inline coating of silicon nanoparticles in a plasma reactor: Reactor design, simulation and experiment

Gas-phase synthesis of nanoparticles (NPs) in hot plasmas is a promising approach to produce pure, highly specific, and complex nanomaterials at large production rates. Post-processing of the material by particle coating, embedding, or surface functionalization is often required to adjust the materials’ properties with respect to their utilization in functional structures. Due to the high surface-to-volume ratio, the nanoparticles’ surface properties strongly influence the processing and thus their applicability. We report on a scalable and continuous gas-phase synthesis process of silicon nanoparticles by a high-temperature single-step plasma process with subsequent inline coating. Our process requires a two-stage supply of process gases: First, silicon nanoparticles (Si-NPs) are formed from the gaseous precursor monosilane (SiH4) after its decomposition in the plasma zone. Secondly, the coating agent ethylene (C2H4) is mixed with the hot, particle-laden gas flow downstream of the plasma zone via a specifically-designed coating nozzle. To facilitate a homogeneous intermixing of C2H4 and the nanoparticle-laden gas stream, fluid dynamics simulations were performed to design and optimize the geometry of the coating nozzle. The process conditions can be varied to tune the decomposition process of gaseous C2H4 in respect to coating the Si-NP surface. As a result, we are able to tune the composition of the nanoparticles. Product characterization by X-ray diffraction, Raman, FTIR and X-ray photoelectron spectroscopy revealed that either SiC, or silicon with a carbon-like or a polyethylene-like shell is produced respectively, with increasing distance of the coating nozzle from the plasma. For all process conditions, spherical, coated particles with a highly-crystalline silicon core were observed as indicated by TEM measurements.