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SARS-CoV-2 Delta and Omicron are globally relevant variants of concern. Although individuals infected with Delta are at risk of developing severe lung disease, infection with Omicron often causes milder symptoms, especially in vaccinated individuals1,2. The question arises of whether widespread Omicron infections could lead to future cross-variant protection, accelerating the end of the pandemic. Here we show that without vaccination, infection with Omicron induces a limited humoral immune response in mice and humans. Sera from mice overexpressing the human ACE2 receptor and infected with Omicron neutralize only Omicron, but not other variants of concern, whereas broader cross-variant neutralization was observed after WA1 and Delta infections. Unlike WA1 and Delta, Omicron replicates to low levels in the lungs and brains of infected animals, leading to mild disease with reduced expression of pro-inflammatory cytokines and diminished activation of lung-resident T cells. Sera from individuals who were unvaccinated and infected with Omicron show the same limited neutralization of only Omicron itself. By contrast, Omicron breakthrough infections induce overall higher neutralization titres against all variants of concern. Our results demonstrate that Omicron infection enhances pre-existing immunity elicited by vaccines but, on its own, may not confer broad protection against non-Omicron variants in unvaccinated individuals.

Background As of early 2022, the Omicron variants are the predominant circulating lineages globally. Understanding neutralizing antibody responses against Omicron BA.1 and BA.2 after vaccine breakthrough infections will provide insights into BA.2 infectivity and susceptibility to subsequent reinfection. Methods Live virus neutralization assays were used to study immunity against Delta and Omicron BA.1 and BA.2 variants in samples from 86 individuals, 24 unvaccinated (27.9%) and 62 vaccinated (72.1%), who were infected with Delta (n = 42, 48.8%) or BA.1 (n = 44, 51.2%). Among the 62 vaccinated individuals, 39 were unboosted (62.9%), whereas 23 were boosted (37.1%). Results In unvaccinated infections, neutralizing antibodies (nAbs) against the three variants were weak or undetectable, except against Delta for Delta-infected individuals. Both Delta and BA.1 breakthrough infections resulted in strong nAb responses against ancestral wild-type and Delta lineages, but moderate nAb responses against BA.1 and BA.2, with similar titers between unboosted and boosted individuals. Antibody titers against BA.2 were generally higher than those against BA.1 in breakthrough infections. Conclusions These results underscore the decreased immunogenicity of BA.1 compared to BA.2, insufficient neutralizing immunity against BA.2 in unvaccinated individuals, and moderate to strong neutralizing immunity induced against BA.2 in Delta and BA.1 breakthrough infections.

Omicron and its subvariants have rendered most authorized monoclonal antibody-based treatments for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ineffective, highlighting the need for biologics capable of overcoming SARS-CoV-2 evolution. These mostly ineffective antibodies target variable epitopes. Here we describe broad-spectrum SARS-CoV-2 inhibitors developed by tethering the SARS-CoV-2 receptor, angiotensin-converting enzyme 2 (ACE2), to known non-neutralizing antibodies that target highly conserved epitopes in the viral spike protein. These inhibitors, called receptor-blocking conserved non-neutralizing antibodies (ReconnAbs), potently neutralize all SARS-CoV-2 variants of concern (VOCs), including Omicron. Neutralization potency is lost when the linker joining the binding and inhibitory ReconnAb components is severed. In addition, a bi-functional ReconnAb, made by linking ACE2 to a bi-specific antibody targeting two non-overlapping conserved epitopes, defined here, shows sub-nanomolar neutralizing activity against all VOCs, including Omicron and BA.2. Given their conserved targets and modular nature, ReconnAbs have the potential to act as broad-spectrum therapeutics against SARS-CoV-2 and other emerging pandemic diseases.

Associations between vaccine breakthrough cases and infection by different SARS coronavirus 2 (SARS-CoV-2) variants have remained largely unexplored. Here we analysed SARS-CoV-2 whole-genome sequences and viral loads from 1,373 persons with COVID-19 from the San Francisco Bay Area from 1 February to 30 June 2021, of which 125 (9.1%) were vaccine breakthrough infections. Vaccine breakthrough infections were more commonly associated with circulating antibody-resistant variants carrying ≥1 mutation associated with decreased antibody neutralization (L452R/Q, E484K/Q and/or F490S) than infections in unvaccinated individuals (78% versus 48%, P = 1.96 × 10

Virus-like particle (VLP) and live virus assays were used to investigate neutralizing immunity against Delta and Omicron SARS-CoV-2 variants in 259 samples from 128 vaccinated individuals. Following Delta breakthrough infection, titers against WT rose 57-fold and 3.1-fold compared with uninfected boosted and unboosted individuals, respectively, versus only a 5.8-fold increase and 3.1-fold decrease for Omicron breakthrough infection. Among immunocompetent, unboosted patients, Delta breakthrough infections induced 10.8-fold higher titers against WT compared with Omicron (p= 0.037). Decreased antibody responses in Omicron breakthrough infections relative to Delta were potentially related to a higher proportion of asymptomatic or mild breakthrough infections (55.0% versus 28.6%, respectively), which exhibited 12.3-fold lower titers against WT compared with moderate to severe infections (p= 0.020). Following either Delta or Omicron breakthrough infection, limited variant-specific cross-neutralizing immunity was observed. These results suggest that Omicron breakthrough infections are less immunogenic than Delta, thus providing reduced protection against reinfection or infection from future variants.

Investigating contamination pathways and hydraulic connections in complex hydrological systems will benefit greatly from multi-tracer approaches. The use of non-toxic synthetic DNA tracers is promising, because unlimited numbers of tracers, each with a unique DNA identifier, could be used concurrently and detected at extremely low concentrations. This study aimed to develop multiple synthetic DNA tracers as free molecules and encapsulated within microparticles of biocompatible and biodegradable alginate and chitosan, and to validate their field utility in different systems. Experiments encompassing a wide range of conditions and flow rates (19 cm/day–39 km/day) were conducted in a stream, an alluvial gravel aquifer, a fine coastal sand aquifer, and in lysimeters containing undisturbed silt loam over gravels. The DNA tracers were identifiable in all field conditions investigated, and they were directly detectable in the stream at a distance of at least 1 km. The DNA tracers showed promise at tracking fast-flowing water in the stream, gravel aquifer and permeable soils, but were unsatisfactory at tracking slow-moving groundwater in the fine sand aquifer. In the surface water experiments, the microencapsulated DNA tracers’ concentrations and mass recoveries were 1–3 orders of magnitude greater than those of the free DNA tracers, because encapsulation protected them from environmental stressors and they were more negatively charged. The opposite was observed in the gravel aquifer, probably due to microparticle filtration by the aquifer media. Although these new DNA tracers showed promise in proof-of-concept field validations, further work is needed before they can be used for large-scale investigations.

The reactions which may occur in the organic phase during mononitration of benzene and toluene under heterogeneous conditions used in industry have been studied by mixing the hydrocarbon with a solution of nitrating acid in either m-mononitrotoluene or mononitrobenzene. Both nitration and oxidation reactions are shown to occur. A separate aqueous phase may be formed during reaction, and distribution of nitric acid into this has an important effect on reaction in the organic phase. The rate of nitration is sensitive to the presence of even traces of sulphuric acid. The ratio of mononitrotoluene isomers formed in the organic phase is the same as under heterogeneous conditions.

Diffusion coefficients of toluene and benzene into aqueous mixtures of nitric and sulphuric acids have been measured at 30°C by use of a laminar jet technique. Equations are presented which correlate the data in terms of the acid concentrations and permit extrapolation to acid mixtures of interest for industrial mononitration reactions. The results show the expected dependence on viscosity of the acid phase and are in agreement with values predicted by the Wilke and Chang correlation.

Solubilities of benzene and toluene in mixtures of nitric and sulphuric acids of various compositions have been measured and also distribution coefficients. Correlations are presented to allow distribution coefficients to be predicted in acid mixtures of compositions typically used for aromatic nitration in industry.

The distribution of isomers in mononitration of toluene is demonstrated to be dependent upon the properties of the solvents involved. An empirical model has been derived to relate the isomer ratio with the dipole moments and dielectric constants of the solvents. Based on this observation, an investigation into the effect of electric field on the distribution of isomers in continuous mononitration of toluene has been carried out.

Session 1: High Speed Trains (I).- Environmental Noise Reduction of Tokaido Shinkansen and Future Prospect.- Distortion of Compression Wave Propagating through Shinkansen Tunnel.- The Influence of the Train Speed on Vibrations Due to High Speed Trains.- High Speed Train Noise Effects on Wildlife and Domestic Livestock.- Wind Tunnel Tests on the Control of Aeroacoustic Noise from High Speed Train.- Session 2: High Speed Trains (II).- Measures to Counteract Micro-pressure Waves Radiating from Tunnel Exits of DB's New Nuremberg-Ingolstadt High-Speed Line.- Acoustic Assessment of Micro-pressure Waves Radiating from Tunnel Exits of DB High-Speed Lines.- High Speed Railway Noise: Assessment of Mitigation Measures.- Noise Measurement Results of Shinkansen High-Speed Test Train (FASTECH360S,Z).- Noise Sources for High Speed Trains: A Review of Results in the TGV Case.- Session 3: Ground Borne Vibrations (I).- Survey of Metro Excitation Frequencies and Coincidence of Different Modes.- Floating Slab Track above Ground for Turnouts in Tram Lines.- Vehicle/Track Impact Due to Passing the Transition between a Floating Slab and Ballasted Track.- Recent Developments in Operational Rail Noise and Vibration in NSW, Australia.- Experimental Validation of a Numerical Model for Subway Induced Vibrations.- A Numerical Model for Re-radiated Noise in Buildings from Underground Railways.- Session 4: Ground Borne Vibrations (II).- The Influence of the Soil on Track Dynamics and Ground-Borne Vibration.- A User-Friendly Prediction Tool for Railway Induced Ground Vibrations: Emission - Transmission - Immission.- Using the PiP Model for Fast Calculation of Vibration from a Railway Tunnel in a Multi-layered Half-Space.- Structure-Borne Noise and Vibration Control for Chatswood Interchange.- Measurements and Investigations at the Floating-Track-Bed System in the North-South Tunnel in Berlin.- Propagation of Vibrations Due to a Tramway Line.- Session 5: General Rolling Noise Aspects (I).- Railway Noise Statistics by Monitoring Stations - Input for Dutch Prediction Method RMR and Track Access Charging.- Measurement and Modelling of Noise from the Arsta Bridge in Stockholm.- Minimising Noise from Viaducts in the Borough Area of London for the Thameslink Programme.- The New German Prediction Model for Railway Noise "Schall 03 2006" - Potentials of the New Calculation Method for Noise Mitigation of Planned Rail Traffic.- Floating Slab Track Re-engineering: Experience Drawn from a Completely Renovated FST Damaged by Major Flooding in Sao Paulo Metro.- Session 6: General Rolling Noise Aspects (II).- In-Car Noise and Carriage Floor Vibration on Different Track Forms and Curvatures in a Metro System.- Experimental and Theoretical Analysis of Railway Bridge Noise Reduction Using Resilient Rail Fasteners in Burgdorf, Switzerland.- Comparison of Two Metrics for Assessing Human Response to Vibration.- A Study on Source Mechanism in the Interior Noise Problem of High Speed Trains.- Reducing the Noise Emission by Increasing the Damping of the Rail: Results of a Field Test.- Session 7: Cost Benefit Considerations of Noise Abatement.- Railway Noise Abatement: The Case for Retrofitting Freight Vehicles with Composite Brake Blocks.- A Systematic Approach for Arriving at Reasonable Heights and Locations for Noise Barriers Adjacent to Railway Lines.- How Can Infrastructure Manager Influence Noise Generation of Rolling Stock.- Acoustic Effectiveness of Damped Wheels and Impact on Life-Cycle Cost of Different Typologies of Passenger Trains.- Mitigation Measures for Open Lines against Vibration and Ground-Borne Noise: A Swiss Overview.- Session 8: Prediction Tools and Theoretical Models (I).- Preliminary Analysis on Effect of Sleeper Pitch on Rail Corrugation at a Curved Track.- A Hybrid Model for Noise Generation from a Railway Wheel Due to Wheel/Rail Impact.- A Time Domain Model for Wheel/Rail Interaction Aiming to Include Non-linear Contact Stiffness and Tangential Friction.- Optimization of Track Parameters, Considering Their Physical Dispersion, to Minimize Rail Corrugation.- Predicting the Effect of Temperature on the Performance of Elastomer-Based Rail Damping Devices.- Estimation of Sound Transmission through Extruded Panels Using a Coupled Waveguide Finite Element-Boundary Element Method.- Session 9: Prediction Tools and Theoretical Models (II).- Squeal Prediction for a Bogied Vehicle in a Curve.- Synthesis of Noise of Operating Vehicles: Development within SILENCE of a Tool with Listening Features.- IMAGINE Rail Noise Sources - A Practical Methodology.- Optimization of a Wheel Damper for Freight Wagons Using FEM Simulation.- Session 10: Grinding, Corrugation and Roughness (I).- Types of Rail Roughness and the Selection of Vibration Isolation Measures.- Rail Roughness Monitoring in the Netherlands.- Rail Roughness Level Assessment Based on High-Frequency Wheel- Immission.- Using the PiP Model for Fast Calculation of Vibration from a Railway Tunnel in a Multi-layered Half-Space.- Structure-Borne Noise and Vibration Control for Chatswood Interchange.- Measurements and Investigations at the Floating-Track-Bed System in the North-South Tunnel in Berlin.- Propagation of Vibrations Due to a Tramway Line.- Session 5: General Rolling Noise Aspects (I).- Railway Noise Statistics by Monitoring Stations - Input for Dutch Prediction Method RMR and Track Access Charging.- Measurement and Modelling of Noise from the Arsta Bridge in Stockholm.- Minimising Noise from Viaducts in the Borough Area of London for the Thameslink Programme.- The New German Prediction Model for Railway Noise "Schall 03 2006" - Potentials of the New Calculation Method for Noise Mitigation of Planned Rail Traffic.- Floating Slab Track Re-engineering: Experience Drawn from a Completely Renovated FST Damaged by Major Flooding in Sao Paulo Metro.- Session 6: General Rolling Noise Aspects (II).- In-Car Noise and Carriage Floor Vibration on Different Track Forms and Curvatures in a Metro System.- Experimental and Theoretical Analysis of Railway Bridge Noise Reduction Using Resilient Rail Fasteners in Burgdorf, Switzerland.- Comparison of Two Metrics for Assessing Human Response to Vibration.- A Study on Source Mechanism in the Interior Noise Problem of High Speed Trains.- Reducing the Noise Emission by Increasing the Damping of the Rail: Results of a Field Test.- Session 7: Cost Benefit Considerations of Noise Abatement.- Railway Noise Abatement: The Case for Retrofitting Freight Vehicles with Composite Brake Blocks.- A Systematic Approach for Arriving at Reasonable Heights and Locations for Noise Barriers Adjacent to Railway Lines.- How Can Infrastructure Manager Influence Noise Generation of Rolling Stock.- Acoustic Effectiveness of Damped Wheels and Impact on Life-Cycle Cost of Different Typologies of Passenger Trains.- Mitigation Measures for Open Lines against Vibration and Ground-Borne Noise: A Swiss Overview.- Session 8: Prediction Tools and Theoretical Models (I).- Preliminary Analysis on Effect of Sleeper Pitch on Rail Corrugation at a Curved Track.- A Hybrid Model for Noise Generation from a Railway Wheel Due to Wheel/Rail Impact.- A Time Domain Model for Wheel/Rail Interaction Aiming to Include Non-linear Contact Stiffness and Tangential Friction.- Optimization of Track Parameters, Considering Their Physical Dispersion, to Minimize Rail Corrugation.- Predicting the Effect of Temperature on the Performance of Elastomer-Based Rail Damping Devices.- Estimation of Sound Transmission through Extruded Panels Using a Coupled Waveguide Finite Element-Boundary Element Method.- Session 9: Prediction Tools and Theoretical Models (II).- Squeal Prediction for a Bogied Vehicle in a Curve.- Synthesis of Noise of Operating Vehicles: Development within SILENCE of a Tool with Listening Features.- IMAGINE Rail Noise Sources - A Practical Methodology.- Optimization of a Wheel Damper for Freight Wagons Using FEM Simulation.- Session 10: Grinding, Corrugation and Roughness (I).- Types of Rail Roughness and the Selection of Vibration Isolation Measures.- Rail Roughness Monitoring in the Netherlands.- Rail Roughness Level Assessment Based on High-Frequency Wheel-Rail Contact Force Measurements.- Session 11: Grinding, Corrugation and Roughness (II).- Testing the New Acoustic Rail Roughness Measurement Standard.- Practical Implementations and Benefits of Highly Accurate Rail Roughness Measurements.- Session 12: New Noise Reduction Technologies (I).- New Rail Dampers at the Railway Link Roosendaal-Vlissingen Tested within the Dutch Innovation Program.- Theoretical Study on Noise Reduction of Rail Component by Use of Rail Absorber.- Reducing Wheel-Rail Interaction Forces and Roughness Growth by Application of Rail Dampers.- Session 13: New Noise Reduction Technologies (II).- Mitigation of Wheel Squeal and Flanging Noise on the Australian Rail Network.- How to Avoid Squeal Noise on Railways State of the Art and Practical Experience.- Noise Reduction Measures at Freight Train Locomotives "Blue Tiger".- Noise Reduction at Urban Hot-Spots by Vehicle Noise Control.- Poster Session.- Directivity of Railway Rolling Noise.- Complex Eigenvalue Analysis of Railway Curve Squeal.- Wave Propagation in Railway Tracks at High Frequencies.- Stability and Transient Analysis in the Modelling of Railway Disc Brake Squeal.- Large-Scale Fatigue Test of Stone Wool Based Anti-vibration Mats.

We report the selective catalytic cleavage of the HIV coat protein gp120, a B cell superantigen, by IgM antibodies (Abs) from uninfected humans and mice that had not been previously exposed to gp120. The rate of IgM-catalyzed gp120 cleavage was greater than of other polypeptide substrates, including the bacterial superantigen protein A. The kinetic parameters of gp120 cleavage varied over a broad range depending on the source of the IgMs, and turnover numbers as great as 2.1/min were observed, suggesting that different Abs possess distinct gp120 recognition properties. IgG Abs failed to cleave gp120 detectably. The Fab fragment of a monoclonal IgM cleaved gp120, suggesting that the catalytic activity belongs to the antibody combining site. The electrophoretic profile of gp120 incubated with a monoclonal human IgM suggested hydrolysis at several sites. One of the cleavage sites was identified as the Lys(432)-Ala(433) peptide bond, located within the region thought to be the Ab-recognizable superantigenic determinant. A covalently reactive peptide analog (CRA) corresponding to gp120 residues 421-431 with a C-terminal amidino phosphonate diester mimetic of the Lys(432)-Ala(433) bond was employed to probe IgM nucleophilic reactivity. The peptidyl CRA inhibited the IgM-catalyzed cleavage of gp120 and formed covalent IgM adducts at levels exceeding a control hapten CRA devoid of the peptide sequence. These observations suggest that IgMs can selectively cleave gp120 by a nucleophilic mechanism and raise the possibility of their role as defense enzymes.

The B cell superantigenic site of the HIV protein gp120 (gp120SAg) is important in viral entry into host cells and gp120SAg binding IgG in the preimmune repertoire reduce the risk of infection. Like the gp120SAg binding function, the innate catalytic function of antibody (Ab) variable domains is subject to deterioration during B cell maturation, and gp120SAg binding Abs are not produced appreciably following infection. We report the selection of catalytic single chain Fv (scFv) and light chain (L chain) clones from the Ab repertoire of patients with lupus, a condition involving increased production of gp120SAg binding Abs. The Ab fragments were isolated by covalent phage selection using electrophilic gp120 analogs. Several selected fragments cleaved gp120 via a nucleophilic mechanism coordinated with noncovalent recognition of gp120(421–433), determined by electrophoretic assays. Certain clones neutralized HIV infection in cultured peripheral blood mononuclear cells (low μg/ml potency), including two scFv clones that neutralized primary clade B, C and D strains. In contrast to lupus patients, studies on polyclonal IgG and IgA from HIV infected patients did not support the presence of an amplified Ab response to gp120SAg. IgAs from a minority of infected subjects with no progression to AIDS 5.5 years following seroconversion displayed increased gp120 hydrolysis compared to rapid progressors (P

Most processes for the solvent extraction of metals involve chemical complex formation between a metal containing ion and an extractant. This is essential both for transfer of the metal to the organic phase and also, in some cases, for the specificity of the extraction. Since a chemical reaction is involved, the rate of transfer between the two phases will depend upon both the rates of the actual transport processes in the two phases and the kinetics of the chemical reaction(s). A knowledge of the overall rate of transfer is obviously important in plant design. However, interest in a full understanding of the rate determining processes has only developed this last decade. Prior to that, most data for design purposes were generated by relatively simple laboratory or pilot plant experiments, usually interpreted in terms of mass transfer alone as with the simpler and already established industrial extraction processes, thus ignoring any possible contribution from a chemical kinetic resistance.

The last decade has seen the application of solvent extraction in the minerals processing field develop rapidly and on a large scale. In the main, previously developed classes of contactor have been employed, although selection between them has been influenced by characteristics of hydrometallurgical applications not necessarily met in other industrial processes using solvent extraction. These include: (a) The very scale of the hydrometallurgical applications, which can involve volumetric throughputs much in excess of other industrial uses of the technique. (b) The fact that the processes involve complex formation between the metal and the extractant, thus possibly introducing a significant chemical kinetic resistance into the mass transfer process. (c) The fact that maintenance of one phase as the continuous (i.e. aqueous in organic or organic in aqueous dispersion) may have significant practical advantage in terms of phase separation rate, losses of reagent by entrainment, contamination of product by entrainment, etc. (d) The probability of fluctuations in feed quality, both in terms of concentrations of the various metals and of solids in suspension, due to variations in the ore being processed and the performance of up-stream units such as clarifiers.

Tramway traffic may produce vibrations propagating in soil leading to vibration annoyance for people living or working in neighbouring buildings. Thus vibration is an important parameter to be considered when planning new lines and dynamic performance evaluation of tramway tracks is necessary to validate or modify the existing means that reduce vibrations. This paper presents experimental and theoretical investigations of vibrations caused by tramway passages in Nantes, France. It focuses on the control of ground-borne vibrations for the whole system, taking into account important elements such as the dynamic vehicle characteristics, the track and the soil behaviour. A complete track-soil-ground model is proposed to predict ground-borne vibrations, so as to estimate a trouble gauge concerning - for example - the impact of a future tramway line.

The European Integrated project SILENCE is dedicated to the reduction of railway and road noise in urban areas. Within this context, SNCF and LMA collaborate in the sub-project B in order to develop a pass-by sound simulation software. This global modelling tool will support parametric studies on the reduction of the noise of a train or a car pass-by, by providing standard indicators (time signature, sound pressure level) and sound samples. It will be used to determine the best combination of optimised sources, developed by manufacturers, in order to reduce the global pass-by noise. In the software, each simulation is based upon the definition of the acoustic sources and the pass-by scenario. Each physical acoustic source on the vehicle is represented by one or several point sources. These point sources radiate either pure tones or broadband noise. A dedicated algorithm is used to simulate each type in an efficient way to reduce the computation time. The characteristics of the sources are obtained either from numerical models, or from standstill and pass-by antenna measurements (carried out in the SILENCE project). As a large source such as a cooling system can not be modelled by several point sources located at close positions, a radiation pattern is allocated to the point source. Dedicated studies are in progress to measure the radiation pattern of classical sources on a train (two series of measurements on a 1:14 scale-model and on a train).