[This corrects the article on p. 1107 in vol. 25, PMID: 42517087.].
A number of meteorites from the desert of Oman, classified as H-chondrites, with known and unknown ages, were studied by using 57Fe Mössbauer spectroscopy to determine their Fe3+-bearing compositions. Mössbauer spectra measured at 78 K were composed of paramagnetic doublets superimposed on magnetic sextets. The doublets are assigned to the silicate minerals olivine and pyroxene and Fe3+ phases. The magnetic sextets in most samples showed the presence of at least three magnetic phases, namely troilite, magnetite and kamacite, which commonly exist in most ordinary chondrites. The relative amounts (area %) of Fe3+ in the known-age meteorites, determined from the Mössbauer spectra, were plotted against their terrestrial ages. The plot was used to estimate the terrestrial ages of meteorites with unknown terrestrial age.
Expro's innovative Octopoda® annulus intervention technology was successfully deployed to remediate sustained casing pressure (SCP) in the B annulus of a gas development well, operated by Petroleum Development Oman (PDO). SCP was detected shortly after cementing the 7 5/8″ production casing, which prevented further drilling and completion operations. The intervention aimed to eliminate SCP by displacing oil-based mud (OBM) from the B annulus with a kill-weight and resin-compatible fluid, followed by resin deployment. A wellhead survey confirmed the correct tool configuration for annulus access, enabling the deployment of a 6.9 mm OD hose to a depth of 65 m. This facilitated the recovery of 14.2 m3 of OBM and its replacement with 1.5 SG calcium bromide (CaBr2) brine, reinstating hydrostatic overbalance and fully removing shut-in casing pressure (SICP). Following OBM removal, a total of 1.7 m3 of resin was circulated through the Octopoda® system and into the annulus, where it was allowed to free-fall to the target treatment depth, establishing a mechanical barrier within the B annulus. The system's ability to access the annulus and mobilize a viscous OBM cap was crucial for subsequent operations. Once the cap was circulated out, highly efficient OBM removal was achieved by leveraging fluid immiscibility and gravity-driven displacement. This process enabled complete OBM removal without the need for the deployed Octopoda® hose to reach the top of cement (TOC). Establishing a circulation path allowed continuous resin deployment, maximizing resin treatment volume while maintaining pressures below the maximum allowable annular surface pressure (MAASP). The annulus intervention Octopoda® system offers significant operational advantages over traditional lubricate-and-bleed methods. The intervention was completed within 14 operational days, allowing PDO to resume drilling and bring the well online without the need for a workover rig. This outcome demonstrates the effectiveness of the annulus intervention Octopoda® system for SCP remediation. The approach offers a replicable methodology for addressing similar integrity challenges, highlighting its value for efficient fluid displacement and resin deployment in complex annular environments.
Precipitation chemistry data provide important information for environmental studies on large-scale element cycling and anthropogenic impacts on our atmosphere, but also for hydrochemical models and groundwater recharge estimations via the Chloride Mass Balance method. Such recharge data play a crucial role in groundwater management, particularly in (semi-)arid areas. Unfortunately, precipitation analyses are often scarce in such regions. This also applies to the Arabian Peninsula, including southern Oman. To overcome this lack of rain chemistry data, we developed a strategy for automatic weekly bulk precipitation sampling, using recently designed automatic rainwater samplers. The integral samples were gathered along an elevation gradient from the Salalah coast to the Dhofar mountains during the Indian Ocean Monsoon seasons 2017 and 2018.Our major ion analyses of the rainwater samples revealed considerable temporal and spatial heterogeneity, in terms of ion proportions and absolute concentrations. Samples from the coast were relatively salty (EC mostly >3000 & mu;S cm- 1) and rich in Na+ and Cl-, reflecting small rain amounts and a sea spray effect. Further inland, solute concentrations were lower, partly due to more precipitation, and ions such as Ca2+ and SO42- gained importance, probably due to calcite and gypsum dust. This pattern reflects the interplay between solute availability (influenced by regional geology, wind direction at different altitudes, and wind speed) and precipitation amounts. Cl-/Br- ratios were fairly uniform and scattered around the seawater value. Combining ion concentrations and rain amounts yielded bulk depositions that showed an erratic pattern along the elevation gradient, i. e., depositions did not decrease steadily in inland direction, as one may assume. This suggests that the occasionally reported approach of collecting a few opportunistic grab samples at a single site is unlikely to yield data that are representative for a larger coastal study area.
Premature unblinding of individual participants is rarely reported in publications, but such unblinding can disrupt vaccine trials by causing worry and drop-out of other participants or “pseudo unblinding,” in which participants or investigators over-interpret certain symptoms as being related to receiving an investigational product. This review summarizes appropriate reasons for unblinding in vaccine trials. Regulatory guidance could be improved by distinguishing guidance for vaccine trials from drug trials, with the recognition that unblinding individual participants in vaccine studies is rarely needed for management of adverse events following immunization.
