Redox and acid-base reactions play important roles in the fate of metal contaminants in soils and sediments. The presence of significant amounts of Cr, Pb and other toxic heavy metals in contaminated soils and sediments is of great environmental concern. Oxidation states and dissolution characteristics of the heavy metals can exert negative effects on the natural environment. Atomic force microscopy (AFM) was used to follow the changes in morphology and structure of reaction products of Cr and Pb formed on mineral surfaces. Nitrate salts of Cr(III) and Pb(II) were used to replace the native exchangeable cations on muscovite and smectite surfaces and the metal-mineral systems were then reacted at different pH's and redox conditions.

For Pb, aggregate morphological forms were found at pH 6.1 and 12.4. At pH 6.1, the mean roughness value was 0.70 nm, and at pH 12.4 it was 5.30 nm. The fractal dimensions were 2.03 at pH 6.1 and 2.05 at pH 12.4. For Cr(III), both layered and aggregate morphological forms were found at pH 6.8 and 10.8. The mean roughness values were 0.90 nm at pH 6.8 and 4.3 nm at pH 10.8. Fractal dimensions for both were 2.00. The effect of redox conditions on morphological characteristics was studied on a smectite substrate. The reduced clays were more compacted than oxidized ones and the reduced clay could reduce Cr(VI) to Cr(III), forming new minerals on the surfaces.

A geochemical equilibrium model, MINTEQA2, was used to simulate the experimental conditions and predict possible reaction products. Simulation results agreed well with data from experiments, providing evidence that modeling can provide a useful “reality check” for such studies. Together, MINTEQA2 and AFM can provide important information for evaluating the morphologies and chemical reactivities of metal reaction products formed on phyllosilicate surfaces under varying environmental conditions.

In the 12 km2 catchment area of Syv creek, Denmark, moderate to high concentrations of nitrate (NO3−) occurred in the upper part of the oxidized zone (oxic-I), but dropped within the lower suboxic part (oxic-II), to below the detection limit in the unoxidized zone. Structural Fe2+ in the clay minerals made up 10 to 12% of the Fe in the oxidized zone and increased to approximately 50% in the unoxidized zone. Concurrent with changes in the distribution of structural Fe2+ the clay mineral constituents changed. Vermiculite was typically found in the oxidized zone whereas chlorite was found in the unoxidized zone only. A conversion of illite and chlorite into vermiculite seems to take place. A significant correlation between NO3− and the amount of reduced Fe2+ in the suboxic (oxic-II) zone, indicates that primary structural Fe2+ in the clay minerals is the reductant in a NO3− reduction process.

This report consists of a study of l-ornithine hydrochloride-vermiculite and of benzylammonium hydrochloride-vermiculite complex. The evolution of these organo-vermiculite structures upon heating is studied by X-ray diffraction (XRD) as well as infrared spectroscopy.

After heating vermiculite saturated with 1-ornithine cations, it shows condensation of interlayer ornithine molecules (peptide complexes). The stacking mode, opposing ditrigonal cavities, is not modified between aminoacid complex and peptide complex.

For vermiculite saturated with benzylammonium cations, the stacking sequence changes through heating by changing benzylammonium to NH4+. This transformation implies a sliding of the layers over each other. The ditrigonal surface cavities become face to face, as in the original mica. There are no random translations as in the starting complex.

Adsorptive-type organoclays, where hydrocarbons adsorb directly to the siloxane surfaces, were studied to find new organic cations and to determine the parameters that produce effective sorbents. Organoclays were prepared from hectorite by cation exchange with small, aromatic organic cation salt solutions. Trimefhylphenylammonium (TMPA) chloride was obtained and iodide salts of commercially-unavailable aromatic cations were synthesized and used to prepare organoclays. An aqueous mixture of benzene, toluene, ethylbenzene, and xylenes (BTEX) consistent with the composition of unleaded gasoline was used in sorption isotherms to compare the sorptive properties of the organoclays. Only the TMPA, methylphenylpyridinium (MPPyr), and trimethylammonium indan (Indan) organoclays were effective BTEX sorbents. Organoclays prepared from methylpyridinium (MPyr), trimethylammonium biphenyl (Biphenyl), and trimethylammonium fluorene (Fluorene) were poor sorbents. The MPPyr and TMPA organoclays preferentially sorbed ethylbenzene, whereas the Indan organoclay preferentially sorbed benzene and toluene. Langmuir-type sorption isotherms for the TMPA, MPPyr, and Indan organoclays implied surface adsorption, whereas linear isotherms suggested that partitioning was the sorptive mechanism for the MPyr, Biphenyl, and Fluorene organoclays. Water hydrating the small MPyr cation and the larger bulk of the Biphenyl and Fluorene cations may have blocked BTEX access to the interlayer siloxane surfaces. Although the rather bulky MPPyr and Indan cations produced effective organoclays, compact size and low hydration are organic cation properties that typically yield effective adsorptive-type organoclays.

The success of the insect sterile technique (IST) in managing insect pests raised the hypothesis that a similar approach could be employed to control weed populations. Here, we investigated the feasibility of employing irradiated sterile pollen as a means to disrupt seed production in dioecious weeds, specifically focusing on Palmer amaranth (Amaranthus palmeri S. Watson). Our goal was to determine the optimal irradiation dose that strikes a balance between inducing sterility and preserving competitiveness, as excessive doses could result in pollen mortality, while low doses may retain fertility. Plants were grown in a greenhouse during the summer of 2020 and spring of 2021. Once they reached the flowering stage, male and female individuals were isolated. Mature pollen samples were collected and exposed to varying dosages (0, 100, 200, 300, 400, and 500 Gy) of gamma rays. These irradiated and non-irradiated pollen samples were used in pollen viability assessments and hand-pollination experiments. In the hand-pollination study conducted in 2020, we employed six pollination treatments using different irradiation doses. The results showed that 300 Gy was the most effective dose, resulting in a maximum reduction of 30% in seed set compared with open pollination when irradiated pollen had prior access to the stigma through artificial pollination before open pollination. In 2021, to simulate real field conditions, three additional treatments were introduced into the study, further confirming the effectiveness of the optimal 300 Gy dose. Our findings indicate that the sterile pollen technique (SPT) using irradiated pollen can be a valuable approach for reducing weed seed production. SPT also holds potential for broad-spectrum weed control by mixing sterile pollen from multiple weed species in a single application. Additionally, it could aid in managing herbicide-resistant weeds that have survived in-season control efforts. This research contributes to the development of novel and sustainable weed management strategies.

Healthcare services have evolved with advances in science, technology and societal needs. Despite being around for two decades, 'X-ray at Home' has seen limited adoption. Understanding its enablers and disablers can lead to insights to develop an accessible healthcare service ecosystem. Healthcare organisations have adopted design thinking to develop new products but healthcare service design is still in its introductory phase. This qualitative study describes the current state of home X-ray services in Mumbai and proposes touchpoints for raising awareness, acceptance and patient experience.

B supergiants (BSGs) lie on the cool end of line-driven wind regime, such that the study of their atmospheres can help us to understand the physics of line-driven winds. So far key features of their spectra, especially in the UV region, could not be reproduced consistently with atmosphere models. This represents a significant gap in our knowledge of their physical properties and behavior, which is particularly striking for BSGs on the cool side of the Bi-Stability Jump (cooler than B1). To address this problem, we analysed a sample of Galactic cool BSGs, with sufficient UV and optical coverage. None of our targets are detected in X-rays with only upper limits existing for some of them.

Laser–plasma accelerators (LPAs) have great potential to realize a compact X-ray free-electron laser (FEL), which is limited by the beam properties currently. Two-color high-intensity X-ray FEL provides a powerful tool for probing ultrafast dynamic systems. In this paper, we present a simple and feasible method to generate a two-color X-ray FEL pulse based on an LPA beam. In this scheme, time-dependent mismatch along the bunch is generated and manipulated by the designed lattice system, enabling FEL lasing at different wavelength within two undulator sections. The time separation between the two pulses can be precisely adjusted by varying the time-delay chicane. Numerical simulations show that two-color soft X-ray FELs with gigawatt-level peak power and femtosecond duration can be generated, which confirm the validity and feasibility of the scheme.

The design and the early commissioning of the ELI-Beamlines laser facility’s 30 J, 30 fs, 10 Hz HAPLS (High-repetition-rate Advanced Petawatt Laser System) beam transport (BT) system to the P3 target chamber are described in detail. It is the world’s first and with 54 m length, the longest distance high average power petawatt (PW) BT system ever built. It connects the HAPLS pulse compressor via the injector periscope with the 4.5 m diameter P3 target chamber of the plasma physics group in hall E3. It is the largest target chamber of the facility and was connected first to the BT system. The major engineering challenges are the required high vibration stability mirror support structures, the high pointing stability optomechanics as well as the required levels for chemical and particle cleanliness of the vacuum vessels to preserve the high laser damage threshold of the dielectrically coated high-power mirrors. A first commissioning experiment at low pulse energy shows the full functionality of the BT system to P3 and the novel experimental infrastructure.

A 1178 J near diffraction limited 527 nm laser is realized in a complete closed-loop adaptive optics (AO) controlled off-axis multi-pass amplification laser system. Generated from a fiber laser and amplified by the pre-amplifier and the main amplifier, a 1053 nm laser beam with the energy of 1900 J is obtained and converted into a 527 nm laser beam by a KDP crystal with 62% conversion efficiency, 1178 J and beam quality of 7.93 times the diffraction limit (DL). By using a complete closed-loop AO configuration, the static and dynamic wavefront distortions of the laser system are measured and compensated. After correction, the diameter of the circle enclosing 80% energy is improved remarkably from 7.93DL to 1.29DL. The focal spot is highly concentrated and the 1178 J, 527 nm near diffraction limited laser is achieved.

IXPE is a NASA/ASI Small Explorer Mission. It will probe the X-ray polarization properties of celestial sources. In particular, for Accretion-powered Millisecond Pulsars (AMPs), IXPE can provide us with unique information on their geometry. These information together with pulse shape modelling will strongly boost the achievable sensitivity on measuring the AMPs mass and the radius. As a case-study, we simulated an observation of SAXJ1808.4-3658 and studied the accuracy that can be achieved in the measured time-dependent Stokes profiles. From these data we estimated how well IXPE will be able to constraint NS geometrical parameters, such as the inclination and hot-spot co-latitude angles.