GRB 081029: A Gamma-Ray Burst with a Multi-Component Afterglow

We present an analysis of the unusual optical light curve of the gamma-ray burst GRB 081029, a long-soft burst with a redshift of z = 3.8479. We combine X-ray and optical observations from the Swift X-Ray Telescope and the Swift UltraViolet/Optical Telescope with ground-based optical and infrared data obtained using the REM, ROTSE, and CTIO 1.3-m telescopes to construct a detailed data set extending from 86 s to approximately 100,000 s after the BAT trigger. Our data cover a wide energy range, from 10 keV to 0.77 eV (1.24 to 16,000 Angstrom). The X-ray afterglow shows a shallow initial decay followed by a rapid decay starting at about 18,000 s. The optical and infrared afterglow, however, shows an uncharacteristic rise at about 3000 s that does not correspond to any feature in the X-ray light curve. Our data are not consistent with synchrotron radiation from a jet interacting with an external medium, a two-component jet, or continuous energy injection from the central engine. We find that the optical light curves can be broadly explained by a collision between two ejecta shells within a two-component jet. A growing number of gamma-ray burst afterglows are consistent with complex jets, which suggests that some (or all) gamma-ray burst jets are complex and will require detailed modelling to fully understand them.Comment: ApJ, in press; 29 pages, 8 figure

Lipoprotein(a) Genotype Influences the Clinical Diagnosis of Familial Hypercholesterolemia

Background Evidence suggests that LPA risk genotypes are a possible contributor to the clinical diagnosis of familial hypercholesterolemia (FH). This study aimed at determining the prevalence of LPA risk variants in adult individuals with FH enrolled in the Italian LIPIGEN (Lipid Transport Disorders Italian Genetic Network) study, with (FH/M+) or without (FH/M-) a causative genetic variant. Methods and ResultsAn lp(a) [lipoprotein(a)] genetic score was calculated by summing the number risk-increasing alleles inherited at rs3798220 and rs10455872 variants. Overall, in the 4.6% of 1695 patients with clinically diagnosed FH, the phenotype was not explained by a monogenic or polygenic cause but by genotype associated with high lp(a) levels. Among 765 subjects with FH/M- and 930 subjects with FH/M+, 133 (17.4%) and 95 (10.2%) were characterized by 1 copy of either rs10455872 or rs3798220 or 2 copies of either rs10455872 or rs3798220 (lp(a) score >= 1). Subjects with FH/M- also had lower mean levels of pretreatment low-density lipoprotein cholesterol than individuals with FH/M+ (t test for difference in means between FH/M- and FH/M+ groups <0.0001); however, subjects with FH/M- and lp(a) score >= 1 had higher mean (SD) pretreatment low-density lipoprotein cholesterol levels (223.47 [50.40] mg/dL) compared with subjects with FH/M- and lp(a) score=0 (219.38 [54.54] mg/dL for), although not statistically significant. The adjustment of low-density lipoprotein cholesterol levels based on lp(a) concentration reduced from 68% to 42% the proportion of subjects with low-density lipoprotein cholesterol level >= 190 mg/dL (or from 68% to 50%, considering a more conservative formula). ConclusionsOur study supports the importance of measuring lp(a) to perform the diagnosis of FH appropriately and to exclude that the observed phenotype is driven by elevated levels of lp(a) before performing the genetic test for FH

Heavy element production in a compact object merger observed by JWST

The mergers of binary compact objects such as neutron stars and black holes are of central interest to several areas of astrophysics, including as the progenitors of gamma-ray bursts (GRBs) 1, sources of high-frequency gravitational waves (GWs) 2 and likely production sites for heavy-element nucleosynthesis by means of rapid neutron capture (the r-process) 3. Here we present observations of the exceptionally bright GRB 230307A. We show that GRB 230307A belongs to the class of long-duration GRBs associated with compact object mergers 4–6 and contains a kilonova similar to AT2017gfo, associated with the GW merger GW170817 (refs. 7–12). We obtained James Webb Space Telescope (JWST) mid-infrared imaging and spectroscopy 29 and 61 days after the burst. The spectroscopy shows an emission line at 2.15 microns, which we interpret as tellurium (atomic mass A = 130) and a very red source, emitting most of its light in the mid-infrared owing to the production of lanthanides. These observations demonstrate that nucleosynthesis in GRBs can create r-process elements across a broad atomic mass range and play a central role in heavy-element nucleosynthesis across the Universe

High Surface Area ZnO-Nanorods Catalyze the Clean Thermal Methane Oxidation to CO2

ZnO nanostructures were synthesized by a combination of non-aqueous and aqueous sol-gel techniques to obtain morphologically different ZnO nanostructures, nanorods, and nanopyramids, featuring oxygen vacancies-rich exposed lattice faces and exhibiting different catalytic properties and activity. In particular, ZnO nanorods with high surface area (36 m2/g) were obtained through a rapid, scalable, and convenient procedure. The materials were tested for complete methane oxidation as an important benchmark reaction that is sensitive to surface area and to the availability of oxygen vacancies. Simple ZnO nanorods derived from nanosized quantum dots showed the best catalytic performance that compared well to that of several literature-reported perovskites, mixed metal oxides, and single-metal oxides in terms of T50 (576 °C) and T90 (659 °C) temperatures. Such a result was attributed to their high surface-to-volume ratio enhancing the availability of catalytically active sites such as oxygen vacancies whose abundance further increased following catalytic application at high temperatures. The latter effect allowed us to maintain a nearly stable catalytic performance with over 90% conversion for 12 h at 700 °C despite sintering. This research shows that ZnO-based nanomaterials with a high surface area are viable alternatives to oxides of commonly applied (but of potentially limited availability) transition metals (La, Mn, Co, Ni) for the complete combustion of methane when working at moderate temperatures (600–700 °C)

High Surface Area ZnO-Nanorods Catalyze the Clean Thermal Methane Oxidation to CO₂

ZnO nanostructures were synthesized by a combination of non-aqueous and aqueous sol-gel techniques to obtain morphologically different ZnO nanostructures, nanorods, and nanopyramids, featuring oxygen vacancies-rich exposed lattice faces and exhibiting different catalytic properties and activity. In particular, ZnO nanorods with high surface area (36 m2/g) were obtained through a rapid, scalable, and convenient procedure. The materials were tested for complete methane oxidation as an important benchmark reaction that is sensitive to surface area and to the availability of oxygen vacancies. Simple ZnO nanorods derived from nanosized quantum dots showed the best catalytic performance that compared well to that of several literature-reported perovskites, mixed metal oxides, and single-metal oxides in terms of T50 (576 °C) and T90 (659 °C) temperatures. Such a result was attributed to their high surface-to-volume ratio enhancing the availability of catalytically active sites such as oxygen vacancies whose abundance further increased following catalytic application at high temperatures. The latter effect allowed us to maintain a nearly stable catalytic performance with over 90% conversion for 12 h at 700 °C despite sintering. This research shows that ZnO-based nanomaterials with a high surface area are viable alternatives to oxides of commonly applied (but of potentially limited availability) transition metals (La, Mn, Co, Ni) for the complete combustion of methane when working at moderate temperatures (600–700 °C)

Catalytic Strategies for the Cycloaddition of Pure, Diluted, and Waste CO₂ to Epoxides under Ambient Conditions

Cyclic organic carbonates represent a relevant class of chemicals that can be prepared from CO₂ by cycloaddition to epoxides. The application of efficient catalysts is crucial in allowing the cycloaddition reaction to proceed under very mild conditions of temperature, pressure, and CO₂ concentration, thus resulting in a sustainable and carbon-balanced approach to CO₂ conversion. This is particularly the case if impure waste CO₂ could be employed as a feedstock. In this Review, we have critically analyzed the burgeoning literature on the cycloaddition of CO₂ to epoxides with the aim to provide state-of-the-art knowledge on the catalysts that can convert CO₂ to carbonates under ambient conditions. These have been systematically organized in families of compounds and critically scrutinized in terms of catalytic activity, availability and mechanistic features. Finally, we provide an overview on the catalytic systems able to function using diluted and impure CO₂ as a feedstock

Super-Stable Metal–Organic Framework (MOF)/Luciferase Paper-Sensing Platform for Rapid ATP Detection

Adenosine triphosphate (ATP) determination has been used for many decades to assess microbial contamination for hygiene monitoring in different locations and workplace environments. Highly sophisticated methods have been reported, yet commercially available kits rely on a luciferase–luciferin system and require storage and shipping at controlled temperatures (+4 or −20 °C). The applicability of these systems is limited by the need for a secure cold chain, which is not always applicable, especially in remote areas or low-resource settings. In this scenario, easy-to-handle and portable sensors would be highly valuable. Prompted by this need, we developed a bioluminescence paper biosensor for ATP monitoring in which a new luciferase mutant was combined with a metal–organic framework (MOF); i.e., zeolitic imidazolate framework-8 (ZIF-8). A paper biosensor was developed, ZIF-8@Luc paper sensor, and interfaced with different portable light detectors, including a silicon photomultiplier (SiPM) and smartphones. The use of ZIF-8 not only provided a five-fold increase in the bioluminescence signal, but also significantly improved the stability of the sensor, both at +4 and +28 °C. The ATP content in complex biological matrices was analyzed with the ZIF-8@Luc paper sensor, enabling detection down to 7 × 10−12 moles of ATP and 8 × 10−13 moles in bacterial lysates and urine samples, respectively. The ZIF-8@Luc sensor could, therefore, be applied in many fields in which ATP monitoring is required such as the control of microbial contamination

Revisiting the Potential of Group VI Inorganic Precatalysts for the Ethenolysis of Fatty Acids through a Mechanochemical Approach

The utilization of biobased feedstocks to prepare useful compounds is a pivotal trend in current chemical research. Among a varied portfolio of naturally available starting materials, fatty acids are abundant, versatile substrates with multiple applications. In this context, the ethenolysis of unsaturated fatty acid esters such as methyl oleate is an atom-economical way to prepare functional C10 olefins with a biobased footprint. Despite the existence of a variety of metathesis catalysts for the latter process, there is a lack of readily available, efficient, and inexpensive catalytic systems based on earth-abundant metals (Mo, W) whose preparation does not require sophisticated syntheses and manipulations. Here, a systematic exploration of homogeneous and heterogeneous inorganic Mo, W (oxy)halides shows that MoOCl4, while inactive as a homogeneous species, forms active and selective silica-supported ethenolysis precatalysts able to reach equilibrium conversion of methyl oleate within a few minutes upon activation with SnMe4. Such heterogeneous MoOCl4-based precatalysts were easily accessed through mechanochemical solvent-free procedures and found to contain, upon characterization by elemental analysis and Raman spectroscopy, isolated (SiO)Mo(O)Cl3 units or polymeric silica-supported [–O(SiO)nMoCl4–nO–]m (n = 1, 2) complexes depending on the molybdenum loading. The former isolated species exhibited a higher catalytic performance. The developed heterogeneous precatalysts could be applied to the ethenolysis of various substrates, including polyunsaturated fatty acid esters and industrial fatty acid methyl ester (FAME) mixtures from palm oil transesterification