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A rapid phase-out of unabated coal use is essential to limit global warming to below 2 °C. This review presents a comprehensive assessment of coal transitions in mitigation scenarios consistent with the Paris Agreement, using data from more than 1500 publicly available scenarios generated by more than 30 integrated assessment models. Our ensemble analysis uses clustering techniques to categorize coal transition pathways in models and bridges evidence on technological learning and innovation with historical data of energy systems. Six key findings emerge: First, we identify three archetypal coal transitions within Paris-consistent mitigation pathways. About 38% of scenarios are ‘coal phase out’ trajectories and rapidly reduce coal consumption to near zero. ‘Coal persistence’ pathways (42%) reduce coal consumption much more gradually and incompletely. The remaining 20% follow ‘coal resurgence’ pathways, characterized by increased coal consumption in the second half of the century. Second, coal persistence and resurgence archetypes rely on the widespread availability and rapid scale-up of carbon capture and storage technology (CCS). Third, coal-transition archetypes spread across all levels of climate policy ambition and scenario cycles, reflecting their dependence on model structures and assumptions. Fourth, most baseline scenarios—including the shared socio-economic pathways (SSPs)—show much higher coal dependency compared to historical observations over the last 60 years. Fifth, coal-transition scenarios consistently incorporate very optimistic assumptions about the cost and scalability of CCS technologies, while being pessimistic about the cost and scalability of renewable energy technologies. Sixth, evaluation against coal-dependent baseline scenarios suggests that many mitigation scenarios overestimate the technical difficulty and costs of coal phase-outs. To improve future research, we recommend using up-to-date cost data and evidence about innovation and diffusion dynamics of different groups of zero or low-carbon technologies. Revised SSP quantifications need to incorporate projected technology learning and consistent cost structures, while reflecting recent trends in coal consumption.

Corrosion under insulation (CUI) is defined as any form of external corrosion that occurs on the underlying metal beneath insulated equipment, due to water ingress through the insulation layer. This type of corrosion is frequently observed in oil and gas production, where insulated piping is prevalent, and has historically remained a predominant materials integrity issue. The prediction and direct visualisation of CUI are challenging tasks because of the coverage of the insulation layer(s) and any external jacketing or cladding. Several factors, including the local/ambient environment, system design, and the piping installation process, can influence how CUI initiates and propagates. In this review, CUI background, CUI monitoring, and CUI mitigation strategies are discussed.

Abstract High entropy alloys represent a unique class of metal alloys, comprising nominally five or more elements in near equiatomic proportions. High entropy alloys have gained significant interest on the basis that the high configurational entropy of such alloy systems is purported to result in a single-phase solid solution structure. While such a single-phase structure can occur in unique systems, it is now appreciated that the definition of high entropy alloys can be broader, with systems comprising only four elements possible of forming single phases, and most five (or more) element systems actually being multi (>2) phases. To this end, the notion of compositionally complex alloys is a more general description, with the concise review herein focusing on the corrosion of compositionally complex alloys (inclusive of high entropy alloys). It is noted that generally, in spite of complex compositions and in many cases complicated microstructural heterogeneity, compositionally complex alloys are nominally corrosion-resistant. This is discussed and aspects of the status and needs are presented.

A rapid coal phase-out is needed to meet the goals of the Paris Agreement, but is hindered by serious challenges ranging from vested interests to the risks of social disruption. To understand how to organize a global coal phase-out, it is crucial to go beyond cost-effective climate mitigation scenarios and learn from the experience of previous coal transitions. Despite the relevance of the topic, evidence remains fragmented throughout different research fields, and not easily accessible. To address this gap, this paper provides a systematic map and comprehensive review of the literature on historical coal transitions. We use computer-assisted systematic mapping and review methods to chart and evaluate the available evidence on historical declines in coal production and consumption. We extracted a dataset of 278 case studies from 194 publications, covering coal transitions in 44 countries and ranging from the end of the 19th century until 2021. We find a relatively recent and rapidly expanding body of literature reflecting the growing importance of an early coal phase-out in scientific and political debates. Previous evidence has primarily focused on the United Kingdom, the United States, and Germany, while other countries that experienced large coal declines, like those in Eastern Europe, are strongly underrepresented. An increasing number of studies, mostly published in the last 5 years, has been focusing on China. Most of the countries successfully reducing coal dependency have undergone both demand-side and supply-side transitions. This supports the use of policy approaches targeting both demand and supply to achieve a complete coal phase-out. From a political economy perspective, our dataset highlights that most transitions are driven by rising production costs for coal, falling prices for alternative energies, or local environmental concerns, especially regarding air pollution. The main challenges for coal-dependent regions are structural change transformations, in particular for industry and labor. Rising unemployment is the most largely documented outcome in the sample. Policymakers at multiple levels are instrumental in facilitating coal transitions. They rely mainly on regulatory instruments to foster the transitions and compensation schemes or investment plans to deal with their transformative processes. Even though many models suggest that coal phase-outs are among the low-hanging fruits on the way to climate neutrality and meeting the international climate goals, our case studies analysis highlights the intricate political economy at work that needs to be addressed through well-designed and just policies.

Atomic hydrogen (H) was introduced into steel (AISI 1018 mild steel) by controlled cathodic pre-charging. The resultant steel sample, comprising about 1 ppmw diffusible H, and a reference uncharged sample, were studied using atomic emission spectroelectrochemistry (AESEC). AESEC involved potentiodynamic polarisation in a flowing non-passivating electrolyte (0.6 M NaCl, pH 1.95) with real time reconciliation of metal dissolution using on-line inductively coupled plasma-atomic emission spectroscopy (ICP-OES). The presence of absorbed H was shown to significantly increase anodic Fe dissolution, as evidenced by the enhanced detection of Fe2+ ions by ICP-OES. We discuss this important finding in the context of previously proposed mechanisms for H-effects on the corrosion of steels.

Objective: To study the prevalence of root angulation through radiographic evaluation using panoramic radiographs and to record the extent of angulation among various teeth. Materials and methods: Panoramic radiographs of 506 patients within the age group of 18 to 70 years (196 males and 310 females) were subjected to a retrospective study for estimating the prevalence of root angulations of various teeth- The root angulations in mesial or distal direction from 20΀ onwards were measured. To test the statistical significance, Chi-square test was used. Data analysis was camed out using SPSS (Statistical Package for the Social Sciences) software, version 14. Results: From the 506 conventional panoramic radiographs screened, a total of 16,192 teeth were examined- Root angulations to the mesial or distal directions were seen in 269 teeth (1.66%). Maxilla (2.43%) showed more prevalence as compared to mandible (0.89%). Individual tooth analysis revealed that maxillary lateral incisors showed the highest percentage of angulation (6.12%). Mandibular incisors, maxillary and mandibular first molars showed the least percentage of angulation (0.29%). Highest degree of root angulations among individual teeth was seen in mandibular first and second premolars (81-90΀). No statistically significant differences were observed between males and females (females: 34.8%; males: 29.1%, p=0.21). Conclusion: Root angulation was most prevalent in the maxillary lateral incisors- The highest degree of root angulation was seen in the mandibular arch, among the mandibular premolars. Angulated roots of teeth influence the planning and execution of their extraction, endodontic, orthodontic and prosthodontic treatments. Orthopantomographs may be routinely employed to evaluate root angulations in large populations and when time and economic constraints are present.

Climate change and the emerging carbon-constrained economy of the 21st Century present new challenges and opportunities for countries of the Middle East and North Africa. This paper discusses the potential for Libya to participate in the Clean Development Mechanism (CDM), the main flexibility mechanism of the Kyoto Protocol, which is designed to reduce greenhouse gas emissions and promote sustainable development. The paper considers the interaction of Libya's history and socio-cultural characteristics with global policy dynamics and economic forces. Libya's geography presents considerable potential in terms of CDM project opportunities, yet key developments would be required before these could be exploited. The nature of Libya's political system and social structures suggest that these developments are unlikely to occur while the Qadhafi regime endures, and therefore that Libya will not be able to engage successfully with the CDM and international mitigation activities in the short term. However, the CDM represents a means to implement capacity building and technical development programs, which will be integral components of reconstruction strategy in the aftermath of the dramatic events of early 2011. Keywords: Libyan energy policy; Clean Development Mechanism; political ecology; socio-economic reform; Kyoto Protocol.

Establishment of totipotency after somatic cell nuclear transfer (NT) requires not only reprogramming of gene expression, but also conversion of the cell cycle from quiescence to the precisely timed sequence of embryonic cleavage. Inadequate adaptation of the somatic nucleus to the embryonic cell cycle regime may lay the foundation for NT embryo failure and their reported lower cell counts. We combined bright field and fluorescence imaging of histone H(2b)-GFP expressing mouse embryos, to record cell divisions up to the blastocyst stage. This allowed us to quantitatively analyze cleavage kinetics of cloned embryos and revealed an extended and inconstant duration of the second and third cell cycles compared to fertilized controls generated by intracytoplasmic sperm injection (ICSI). Compared to fertilized embryos, slow and fast cleaving NT embryos presented similar rates of errors in M phase, but were considerably less tolerant to mitotic errors and underwent cleavage arrest. Although NT embryos vary substantially in their speed of cell cycle progression, transcriptome analysis did not detect systematic differences between fast and slow NT embryos. Profiling of amino acid turnover during pre-implantation development revealed that NT embryos consume lower amounts of amino acids, in particular arginine, than fertilized embryos until morula stage. An increased arginine supplementation enhanced development to blastocyst and increased embryo cell numbers. We conclude that a cell cycle delay, which is independent of pluripotency marker reactivation, and metabolic restraints reduce cell counts of NT embryos and impede their development.

Evaluation capacity building (ECB) continues to attract the attention and interest of scholars and practitioners. Over the years, models, frameworks, strategies, and practices related to ECB have been developed and implemented. Although ECB is highly contextual, the evolution of knowledge in this area depends on learning from past efforts in a structured approach. The purpose of the present article is to integrate the ECB literature in evaluation journals. More specifically, the article aims to answer three questions: What types of articles and themes comprise the current literature on ECB? How are current practices of ECB described in the literature? And what is the current status of research on ECB? Informed by the findings of the review, the article concludes with suggestions for future ECB practice and scholarship.

We theoretically investigate the dependence of the enhancement of optical near-fields at nanometric tips on the shape, size, and material of the tip. We confirm the strong dependence of the field enhancement factor on the radius of curvature. In addition, we find a surprisingly strong increase of field enhancement with increasing opening angle of the nanotips. For gold and tungsten nanotips in the experimentally relevant parameter range (radius of curvature $\geqslant 5\;{\rm nm}$ at $800\;{\rm nm}$ laser wavelength), we obtain field enhancement factors of up to $\sim 35$ for Au and $\sim 12$ for W for large opening angles. We confirm this strong dependence on the opening angle for many other materials featuring a wide variety in their dielectric response. For dielectrics, the opening angle dependence is traced back to the electrostatic force of the induced surface charge at the tip shank. For metals, the plasmonic response strongly increases the field enhancement and shifts the maximum field enhancement to smaller opening angles.

Many organizations now have evaluation policies. Because formal evaluation policies intend to frame evaluation practice, it is important to understand the aims of policies and their influence on practice. Evaluation theory is also intended to guide practice; therefore, the extent to which policies are informed by theory is also important to consider, given the related purposes of evaluation theories and policies. Because evaluation policies have emerged with greater occurrence relatively recently, the conceptual and empirical work on the theory-policy-practice connection is limited. Our aim in this article is to flesh out the intersection between evaluation theory, policy, and practice. As illustrative examples, we discuss the three policies in terms of methods, use, and valuing--three core dimensions of evaluation theory. The article concludes with a set of reflections on the different strategies for and implications of a stronger integration of evaluation theory in evaluation policies.

The 1990 film "The Hunt for Red October" (based on Tom Clancy's 1984 debut novel of the same name) featured actors like Sean Connery and Alec Baldwin, but the star of the movie for physicists was a revolutionary new magnetohydrodynamic (MHD) marine propulsion system. The so-called "caterpillar drive" worked with no moving parts, allowing a nuclear missile-armed Soviet submarine to approach the U.S. coast undetected. As the submarine captain (played by Connery) said, "Once the world trembled at the sound of our rockets … now they will tremble again--at the sound of our silence." MHD propulsion is not fictional: real-life prototypes include the "EMS-1," a 3.0-m submarine that achieved speeds of 0.4 m/s during tests in California in 1966, and the "ST-500," a 3.6-m boat that reached 0.6 m/s in Japan in 1979. The world's first and so far only full-sized MHD-propelled craft, "Yamato-1," carried 10 people at speeds of up to 15 km/h during successful sea trials in Kobe, Japan, in 1992. The "Yamato-1" has since been put up on blocks (Fig. 1) and interest in this form of marine propulsion has apparently waned. Why? Motivated by this question, and by the possibility of engaging students with a simple but dramatic demonstration, we built and tested a small-scale MHD boat that can easily be replicated by instructors at low cost in a classroom setting. Our treatment differs in emphasis and is complementary to an excellent earlier article in this journal by Font and Dudley. Other useful discussions are in Refs. 6-10 and a typical textbook account appears in Ref. 11.

Author(s): Haofeng Xu [sup.1] , Yiou He [sup.2] , Kieran L. Strobel [sup.1] , Christopher K. Gilmore [sup.1] , Sean P. Kelley [sup.1] , Cooper C. Hennick [sup.1] , Thomas [...], Since the first aeroplane flight more than 100 years ago, aeroplanes have been propelled using moving surfaces such as propellers and turbines. Most have been powered by fossil-fuel combustion. Electroaerodynamics, in which electrical forces accelerate ions in a fluid.sup.1,2, has been proposed as an alternative method of propelling aeroplanes--without moving parts, nearly silently and without combustion emissions.sup.3-6. However, no aeroplane with such a solid-state propulsion system has yet flown. Here we demonstrate that a solid-state propulsion system can sustain powered flight, by designing and flying an electroaerodynamically propelled heavier-than-air aeroplane. We flew a fixed-wing aeroplane with a five-metre wingspan ten times and showed that it achieved steady-level flight. All batteries and power systems, including a specifically developed ultralight high-voltage (40-kilovolt) power converter, were carried on-board. We show that conventionally accepted limitations in thrust-to-power ratio and thrust density.sup.4,6,7, which were previously thought to make electroaerodynamics unfeasible as a method of aeroplane propulsion, are surmountable. We provide a proof of concept for electroaerodynamic aeroplane propulsion, opening up possibilities for aircraft and aerodynamic devices that are quieter, mechanically simpler and do not emit combustion emissions.A solid-state propulsion system can sustain powered flight, as demonstrated by an electroaerodynamically propelled heavier-than-air aeroplane.

Michael Knapp, Anja Flach and Ercan Ayboga Revolution in Rojava: Democratic Autonomy and Women's Liberation in Syrian Kurdistan, London: Pluto Press, 2016; 320 pp.: ISBN 9780745336640, 16.99 [pounds sterling] This [...]

Michael Roberts The Long Depression: How It Happened, Why It Happened, and What Happens Next, Chicago, IL: Haymarket Books, 2016; $19 There was a cheer on social media when Iceland [...]