New constraints on the formation of lunar mafic impact melt breccias from S‐Se‐Te and highly siderophile elements

Mass fractions of the siderophile volatile elements S, Se, and Te were determined together with highly siderophile elements (HSE) and osmium isotope ratios in multiple aliquots of five lunar mafic impact melt breccias. The impactites were sampled from presumably Imbrium‐related ejecta deposits at the Apollo 14, 15, and 16 landing sites. As in many mafic impact melt breccias, all studied impactites display fractionated siderophile element patterns characteristic of differentiated metal, interpreted to reflect metal‐rich impactor material from the core of a differentiated planetesimal. The compositional record of Fra Mauro crystalline matrix breccias and recent constraints on the time of their formation suggest that the admixture of this differentiated metal component to the Procellarum KREEP Terrane occurred before the Imbrium basin was formed. The impact melt rock portion of dimict breccia 61015 displays fractionations of HSE like other mafic impact melt breccias, but CI chondrite‐like ratios of S, Se, Te, and Ir. Preservation of these contrasting impactor signatures in a single impactite sample demonstrates mixing of differentiated metal and CI chondrite‐like impactor material and their homogenization in an impact melt sheet. Correlations of highly siderophile element ratios between impactites from different Apollo landing sites suggest that siderophile element inventories of many lunar impactites were affected by similar mixing processes. Mass fractions and ratios of S, Se, and Te in other mafic impact melt breccias closely resemble those of pristine mafic target rocks

Influential Article Review - Sustainable Supply Chain Management

This paper examines supply chain management. We present insights from a highly influential paper. Here are the highlights from this paper: This manuscript examines the impact of supply chain uncertainty on environmental management spending in manufacturing plants. Building on the attention-based view of the firm (ABV), the basic premise is that with increased uncertainty in the supply chain, managers’ attention to environmental management lessens which in turn leads to (i) fewer resources devoted to green issues within the plant and (ii) a bias to use resources toward less disruptive pollution control approaches rather than pollution prevention approaches. Data from a survey of 251 Canadian manufacturing plants was used to test the link between the level of uncertainty in the supply chain and environmental management decisions. The results indicate that supply chain uncertainty does not have a substantial impact on the level of environmental spending in a plant but has a substantial and significant impact on the allocation of the spending between pollution prevention and pollution control. More particularly, as supply chain uncertainty increases, organizations shift their resources away from pollution prevention to favor pollution control approaches. For our overseas readers, we then present the insights from this paper in Spanish, French, Portuguese, and German

Silicon and iron isotopes in components of enstatite chondrites: Implications for metal–silicate–sulfide fractionation in the solar nebula

Silicon and iron isotope compositions of different physically separated components of enstatite chondrites (EC) were determined in this study to understand the role of nebular and planetary scale events in fractionating Si and Fe isotopes of the terrestrial planet-forming region. We found that the metal–sulfide nodules of EC are strongly enriched in light Si isotopes (δ30Si ≥ −5.61 ± 0.12‰, 2SD), whereas the δ30Si values of angular metal grains, magnetic, slightly magnetic, and non-magnetic fractions become progressively heavier, correlating with their Mg# (Mg/(Mg+Fe)). White mineral phases, composed primarily of SiO2 polymorphs, display the heaviest δ30Si of up to +0.23 ± 0.10‰. The data indicate a key role of metal–silicate partitioning on the Si isotope composition of EC. The overall lighter δ30Si of bulk EC compared to other planetary materials can be explained by the enrichment of light Si isotopes in EC metals along with the loss of isotopically heavier forsterite-rich silicates from the EC-forming region. In contrast to the large Si isotope heterogeneity, the average Fe isotope composition (δ56Fe) of EC components was found to vary from −0.30 ± 0.08‰ to +0.20 ± 0.04‰. A positive correlation between δ56Fe and Ni/S in the components suggests that the metals are enriched in heavy Fe isotopes whereas sulfides are the principal hosts of light Fe isotopes in the non-magnetic fractions of EC. Our combined Si and Fe isotope data in different EC components reflect an inverse correlation between δ30Si and δ56Fe, which illustrates that partitioning of Si and Fe among metal, silicate, and sulfidic phases has significantly fractionated Si and Fe isotopes under reduced conditions. Such isotope partitioning must have occurred before the diverse components were mixed to form the EC parent body. Evaluation of diffusion coefficients of Si and Fe in the metal and non-metallic phases suggests that the Si isotope compositions of the silicate fractions of EC largely preserve information of their nebular processing. On the other hand, the Fe isotopes might have undergone partial or complete re-equilibration during parent body metamorphism. The relatively uniform δ56Fe among different types of bulk chondrites and the Earth, despite Fe isotope differences among their components, demonstrates that the chondrite parent bodies were not formed by random mixing of chondritic components from different locations in the disk. Instead, the chondrite components mostly originated in the same nebular reservoir and Si and Fe isotopes were fractionated either due to gas–solid interactions and associated changes in physicochemical environment of the nebular reservoir and/or during parent body processing. The heavier Si isotope composition of the bulk silicate Earth may require accretion of chondritic and/or isotopically heavier EC silicates along with cumulation of refractory forsterite-rich heavier silicates lost from the EC-forming region to form the silicate reservoir of the Earth

Metasomatized lithospheric mantle for Mesozoic giant gold deposits in the North China craton

The origin of giant lode gold deposits of Mesozoic age in the North China craton (NCC) is enigmatic because high-grade metamorphic ancient crust would be highly depleted in gold. Instead, lithospheric mantle beneath the crust is the likely source of the gold, which may have been anomalously enriched by metasomatic processes. However, the role of gold enrichment and metasomatism in the lithospheric mantle remains unclear. Here, we present comprehensive data on gold and platinum group element contents of mantle xenoliths (n = 28) and basalts (n = 47) representing the temporal evolution of the eastern NCC. The results indicate that extensive mantle metasomatism and hydration introduced some gold (<1–2 ppb) but did not lead to a gold-enriched mantle. However, volatile-rich basalts formed mainly from the metasomatized lithospheric mantle display noticeably elevated gold contents as compared to those from the asthenosphere. Combined with the significant inheritance of mantle-derived volatiles in auriferous fluids of ore bodies, the new data reveal that the mechanism for the formation of the lode gold deposits was related to the volatile-rich components that accumulated during metasomatism and facilitated the release of gold during extensional craton destruction and mantle melting. Gold-bearing, hydrous magmas ascended rapidly along translithospheric fault zones and evolved auriferous fluids to form the giant deposits in the crust

Turtles From an Arkadelphia Formation—Midway Group Lag Deposit (Maastrichtian—Paleocene), Hot Spring County, Arkansas, USA

The Arkadelphia Formation—Midway Group (Maastrichtian—Paleocene) contact near Malvern, Arkansas preserves a K-Pg boundary assemblage of turtle species consisting of skull, shell, and non-shell postcranial skeletal elements. The Malvern turtles are preserved within a coquina lag deposit that comprises the basalmost Midway Group and also contains an abundance of other reptiles, as well as chondrichthyans, osteichthyans, and invertebrates. This coquina lag deposit records a complex taphonomic history of exhumation and reburial of vertebrate skeletal elements along a dynamic ancestral shoreline in southwestern Arkansas during the late Cretaceous-early Paleocene. Based on stratigraphic occurrence, the Malvern turtle assemblage indicates that these marine reptiles were living at or near the time of the K-Pg mass extinction and represent some of the latest Cretaceous turtles yet recovered from the Gulf Coastal Plain of the United States

High and Low Computer Self-Efficacy Groups and Their Learning Behavior from Self-Regulated Learning Perspective While Engaged in Interactive Learning Modules

The purpose of this research was to investigate high school students’ computer self-efficacy (CSE) and learning behavior in a selfregulated learning (SRL) framework while utilizing an interactive learning module. The researcher hypothesizes that CSE is reflected on cognitive actions and metacognitive strategies while the students are engaged with interactive learning modules. Two research questions guided this research: (1) how is students’ CSE while engaged in interactive learning modules? and (2) how do high and low CSE groups plan and monitor their cognitive action, and regulate their monitoring strategies based on their CSE level? The research used a mixedmethods approach to answer the research questions. This study utilized a SRL framework that covered self-efficacy, cognitive actions, and metacognitive components. While self-efficacy was represented by CSE, metacognitive component was represented by planning, monitoring, and regulating strategies. Cognitive actions represent contextual activities while using interactive learning modules. One hundred students from two high schools, InTech Collegiate and Logan High Schools, completed activities in this study. Each student worked on three modules, namely Boolean Logic, Minimum Spanning Tree, and Modeling Using Graphs. Three different forms of data were gathered for analysis. These data included questionnaires, screen captured videos, and audio recordings of interviews. The findings of this study revealed that the students achieved the highest average score on beginning skills compared to advanced skills and file and software skills for their CSE. Furthermore, screen-captured video analysis showed that there were different profiles of cognitive actions and metacognitive strategies between high and low CSE groups in terms of the strategy changes and duration of their strategies. Issues gathered from interview analysis between these two groups were also elaborated

Biochemical Profile and Productive Performance in Dairy Cows with Lameness During Postpartum Period

Background: Lameness in dairy cows is classified as a gait change caused by multifactorial process. The phase of the peripartum causes intense physiological changes for the adaptation of late gestation and onset of lactation. The aim of this study was to characterize the changes in the biochemical profile and productive performance in dairy cows with lameness during postpartum period.Materials, Methods & Results: This study was conducted at the University of São Paulo farm, in Pirassununga, São Paulo State, Brazil, from January to March 2017. A total, of 48 multiparous (2 to 3 lactations and 3-4 years old) dairy cows, that had the milk production of 9,200 kg/ dairy cow in a period of 305 days in the previous lactation, were included in the study. All cows were managed under the same conditions and nutritional regimen. Evaluation of body condition score was performed by a single person on -18, -12, -8, -5, and -2 days before parturition, at parturition, and on days 1, 7, 14, 21, 30, 45 and 60 after parturition. Milk production was recorded on days 7, 14, 21, 30, 45 and 60 after parturition and saved in the software program. Blood samples were performed on -18, -12, -8, -5, and -2 days before parturition, at parturition, and on days 1, 7, 14, 21, 30, 45 and 60 after parturition. Blood samples were assayed for albumin, calcium, cholesterol, triglycerides, non-esterified fatty acids, β-hydroxybutyrate, urea, creatinine, gamma-glutamil-transferase and total protein concentrations. Dairy cows were divided into a lame group (11) and normal group (37) based on locomotion score from parturition to seven days postpartum. Lame cows was classified if their score was > 2, and normal cows was classified if their score was ≤ 2 and free of any disease. Dairy cows that suffer by any health disorder other than lameness were excluded from this study. Cow diagnosed with lameness outside the diagnostic period were excluded from this study. The averages of the milk production, body condition score and biochemical profile were compared with the Tukey’s test. Lame cows showed lower (P < 0.05) concentrations of albumin (on days -18 -12, -8, -5, -2 relative to parturition, at parturition, and on days 7, 14, 21, 45 and 60 after parturition) calcium (on days -18, -12, -8, -5 and -2 before parturition, and on days 7, 14, 21, 45 and 60 after parturition), cholesterol (on days -12, -8, -5 before parturition and on days 7, 14, 21, 30, 45 and 60 after parturition) than normal cows. Cow with lameness showed higher (P < 0.05) concentration of triglyceride (on days 7, 14, 21, 30, 45 and 60 after parturition), non-esterified fatty acids (on days 1, 7, 14, 21, 30, 45 and 60 after parturition) and β-hydroxybutyrate (on days -12, -5 and -2 before parturition, at parturition, and on days 1, 14, 21 and 30 after parturition) than normal group. Cows with lameness presented higher (P < 0.05) values of body condition score on days -18, -12 and -8 before parturition, and lower (P < 0.05) values on days 7, 14, 21, 30, 45 and 60 after parturition than normal cows. Milk production was lower (P < 0.05) for cows with lameness (on days 7, 14, 21, 30, 45 and 60 after parturition) than normal cows.Discussion: The overall prevalence of lameness in the evaluated period was 22.92% (11/48). Among lame cows, 07 presented laminitis, 02 had interdigital hyperplasia and 02 had sole ulcer. Our findings prove that the biochemical profile and productivity of dairy cows during the peripartum and postpartum period were affected by lameness at the early lactation.

Planetary accretion and core formation inferred from Ni isotopes in enstatite meteorites

Nickel is a siderophile and near-refractory element, making its isotopes a potential tool for tracing planetary accretion and differentiation. However, the origin of the Ni stable isotope difference between bulk silicate Earth (BSE) and chondrites remains enigmatic. To address this problem, we report high precision Ni stable isotope data of enstatite chondrites and achondrites that possess similar mass independent O and Ni isotope compositions like the Earth-Moon system. Bulk enstatite chondrites have δ60/58Ni values of 0.24 ± 0.08 ‰ (2 s.d., n = 13). Enstatite achondrites, including main-group aubrites, Shallowater and Itqiy, show relatively large δ60/58Ni variations, ranging from 0.03 ± 0.02 ‰ to 0.57 ± 0.04 ‰. This could reflect fractionations between sulfide and metal phases, as is evidenced by correlation between their S/Ni ratios and δ60/58Ni values. In enstatite achondrites, Ni is mainly hosted in metal and to a lesser extent in sulfides, so δ60/58Ni values in enstatite achondrites may represent the Ni isotopic values of the cores of their parent bodies. The overlapping δ60/58Ni values between bulk enstatite achondrites and enstatite chondrites indicate limited Ni stable isotope fractionation during core formation processes on reduced, sulfur-rich parent bodies. The Ni stable isotope gap between chondrites and the BSE could be possibly explained by chondrule-rich accretion model