bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of Network Re-Formation in Hydrolytic Degraded AFR700B Polyimide Resin
Authors: Lee Andre
Published: August 2002

Dynamic mechanical spectrometry was used to investigate the network formation processes during the high-temperature isothermal post-cure of virgin and hydrolytic degraded AFR700B resin. Upon exposure to hydrolytic conditions, a significant degradation in physical and mechanical properties of newly developed high-temperature PMR type polyimide resins (AFR700B) was observed. In this study we are particularly interested in the kinetics and the controlling mechanism of the network formation and re-formation processes at the high-temperature post-cure stage. In situ viscoelastic experiments were performed at a temperature of 400 °C. At this temperature the curing of polymer resin continues, thus the isochronal elastic modulus increases as the curing time increases. Furthermore, it was possible to perform a time–curing time superposition using these isothermal elastic modulus curves. This time–curing time shift-rate is then used as a direct measure of the kinetics of polyimide network formation. Interestingly, in this study we found that the time–curing time shift-rate for the hydrolytic degraded samples was identical to the time–curing time shift-factor of virgin ‘ascured’ formulated samples. This observation does not necessarily imply that the chemistry of polyimide network formation is the same, but instead that the controlling mechanism of network formation must be identical.
Crosslinking in Phenylethynyl-Terminated Polyimides
Authors: Hinkley J A , Jensen B J
Published: August 2002

Stress relaxation of cured phenylethynyl-terminated polyimides was used to estimate their equilibrium rubbery moduli. The corresponding concentrations of elastically effective chains derived from classical rubber elasticity theory were less than one-fifth what would be expected if every chain end participated in a crosslink. A model is proposed to allow the calculation of the average crosslink functionalities.
LC Polyimides 31. Non-Crystalline Cholesteric Poly(Ester-Imide)s Based on Isosorbide and 1,6-Hexanediol
Authors: Kricheldorf Hans R , Krawinkel Thorsten
Published: August 2002

Numerous cholesteric copoly(ester-imide)s were prepared by polycondensation of N-(4-carboxyphenyl)trimellitimide (in the form of the dichloride) with isosorbide and various diphenols. 1, 6-hexanediol was incorporated as a flexibilizing component in various molar ratios. In two cases 1, 1′-decanediol was used. All copoly(ester-imide)s proved to be non-crystalline materials with glass transition temperatures ( Tgs) between 110 and 180 °C and a broad cholesteric melt. Most copoly(ester-imide)s derived from substituted hydroquinones were capable of forming a Grandjean texture upon shearing and of fixing the Grandjean texture upon cooling below Tg. However, 2, 7-dihydroxynaphthalene proved to be unfavourable for the formation of a Grandjean texture.
A Thiophene-Based Liquid Crystalline Aromatic Polyamide
Authors: Stompel Semyon , Samulski Edward T , Preston Jack , Hsiaok Benjamin S , Gardner KennCorwin H , Shih Hsiang
Published: August 2002

We have synthesized a liquid crystalline, aromatic polyamide from p-phenylene diamine (PPD) and 2, 5-thiophene dicarboxylic acid (Th). The new polymer, poly( p-phenylene thiophenylamide), abbreviated PPD-Th, like its terephthalic acid precursor, poly( p-phenylene terepthalamide) (PPD-T), exhibits a lyotropic mesophase in concentrated sulphuric acid solutions. Polarizing optical microscopy and deuterium NMR show that concentrated PPD-Th solutions exhibit nematic-to-isotropic phase transitions at a much lower temperature than comparable PPD-T solutions. More importantly, unlike PPD-T, lyotropic PPD-Th solutions do not form a crystallo-solvate complex gel phase at room temperature, i.e. the fluid PPD-Th mesophase persists below 300 K enabling the spinning of PPD-Th fibres from a lyotropic dope at ambient temperatures. Thermogravimetric analysis shows that the 2, 5-thiophene heterocycle in the PPDTh backbone does not significantly diminish its thermal stability relative to that of PPD-T. Preliminary x-ray diffraction results show that PPD-Th crystallizes in a tentative two-chain, orthorhombic unit cell with dimensions a = 3.73 Å, b = 5.04 Å and c = 25.20 Å (fibre axis). The fibre repeat corresponds to two chemical repeats related by a twofold screw axis. Mechanical properties (tensile strength, modulus and elongation to break) are presented for as-spun and heat-treated PPD-Th fibres.
Organo-Soluble Polyimides: Synthesis and Characterization of Polyimides Containing Phenylated p-Biphenyl and p-Terphenyl Units
Authors: Harris Frank W , Sakaguchi Yoshimitsu , Shibata Mitsuhiro , Cheng Stephen Z D
Published: August 2002

4, 4′-diamino-2, 2′-diphenylbiphenyl (1), 4,4″-diamino-2′, 3′, 5′-triphenyl- p-terphenyl (2a) and 4,4″-diamino-2′, 3′, 5′, 6′-tetraphenyl- p-terphenyl (2b) have been polymerized with several aromatic dianhydrides in refluxing m-cresol containing isoquinoline to afford a series of phenylated polyimides. The polymerization mixtures of 1 and 3, 3′, 4, 4′-biphenyltetracarboxylic dianhydride (BPDA) and 3, 3′4, 4′-benzophenonetetracarboxylic dianhydride (BTDA) and of 2a and pyromellitic dianhydride (PMDA) set to gel-like structures upon cooling. The gels, which displayed optical anisotropy typical of a liquid crystalline-like phase, could be dissolved by heating and re-formed by cooling. Although the p-catenated, rigid-rod polymers obtained from the diamines and PMDA were only soluble in concentrated sulphuric acid, the polymers that were prepared from 1 and 2a and 3, 3′, 4, 4′-diphenylethertetracarboxylic dianhydride (ODPA), 3, 3′, 4, 4′-diphenylsulphonetetracarboxylic dianhydride (DSDA) and 2, 2-bis[4-(1, 2-dicarboxyphenyl)]-1, 1, 1, 3, 3, 3-hexafluoropropane dianhydride (6FDA) were soluble in N-methyl-2-pyrrolidinone (NMP), m-cresol and chlorinated solvents. In general, polymers prepared from 2a were the most soluble, while polymers prepared from 2b were the least soluble. The intrinsic viscosities of the polymers ranged from ′.61 to 5.1 dl g−1 in concentrated sulphuric acid or NMP at 3′°C. The glass transition temperatures of most of the polymers could not be detected with differential scanning calorimetry. The temperatures at which the polymers underwent 5% weight losses when subjected to thermal gravimetric analysis ranged from 5″ to 6′°C in both air and nitrogen. Several of the polymers could be solution cast into thin, water-white flexible films.
Studies on a Miscible Polyimide Blend
Authors: Campbell J A , Goodwin A A , Mercer F W , Reddy V
Published: August 2002

Blends of polyimides XU-218 and PEI were investigated using differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis and adhesive bond testing. The thermal stability of the blends increased as the proportion of PEI increased while the α-relaxation of the blends occurred at a slower rate and was broader and more cooperative in some blends, compared with the pure polymers. Physical aging of the pure polymers and blends in the glass state revealed changes in relaxation rate and lost enthalpy that were also consistent with blends not behaving as simple mixtures. The dynamic mechanical and physical aging behaviour was attributed to an increase in density on blending which decreased the unoccupied volume and increased the constraints on molecular mobility, as well as to the presence of concentration fluctuations. The adhesive properties of the blends were also investigated and bond strength was found to vary with blend composition and test temperature.
Properties of Imide Oligomers Containing Pendent Phenylethynyl Groups
Authors: Connell J W , Smith J G , Hergenrother P M
Published: August 2002

As part of a programme to develop high-performance/high-temperature structural resins for aeronautical applications, imide oligomers containing pendent phenylethynyl groups were prepared, characterized, thermally cured and the cured resins evaluated as films, mouldings, adhesives and composites matrices. Initially a diamine containing a pendent phenylethynyl group (3, 5-diamino-4′-phenylethynylbenzophenone) was prepared and characterized. This compound was used to make amide acid and subsequently imide oligomers containing pendent phenylethynyl groups. In order to control the distance between reactive sites, the concentration of pendent phenylethynyl groups was varied randomly along the oligomer backbone. The amide acid oligomers in N-methyl-2-pyrrolidinone were processed into thin films, adhesive tape, carbon fibre prepreg and also converted into imide powder. After initial screening work was performed on unoriented thin films, imidized powders and neat resin mouldings to assess glass transition temperature, mechanical properties (tensile properties and fracture toughness), melt flow behaviour and processability, one particular formulation was scaled up for more comprehensive evaluation. This imide oligomer containing pendent phenylethynyl groups was fabricated into adhesive and composite specimens under 1.4 MPa for1hat 350–371 °C. Excellent mechanical properties were obtained at room temperature and 177 °C. The properties of this material are compared with those of a material of similar composition and molecular weight containing only terminal phenylethynyl groups.
Processing and Properties of IM7/LARC™ -Si Polyimide Composites
Authors: Hou T H , Bryant R G
Published: August 2002

LARC™-SI (NASA Langley Research Center-Soluble Imide) is an aromatic thermoplastic polyimide. LARC™-SI is synthesized from equimolar amounts of oxydiphthalic anhydride (ODPA), 3, 3′, 4, 4′-biphenyltetracarboxylic dianhydride (BPDA) and the equivalent amount of 3, 4′-oxydianiline (3, 4′-ODA). Phthalic anhydride (PA) was used as an endcapper to control molecular weight. A 30% solid LARC™-SI solution (in NMP/Xylene: 9/1 v/v) with 3% stoichiometric imbalance was made into unidirectional long-fibre-reinforced prepregs. Thermal properties, volatile depletion behaviour and resin rheology were thoroughly characterized. Using this information, two composite moulding cycles were developed that consistently yielded well consolidated, void-free laminates. Composite mechanical properties such as short-beam shear strength, longitudinal and transverse flexural strength and flexural modulus, longitudinal tensile strength and notched and un-notched compression strengths, fracture toughness, open-hole compression strength and compression after impact (CAI) strength were measured at room temperature (RT) and elevated temperatures. LARC™-SI composite exhibited very good toughness and damage tolerance. The interlaminar fracture toughness and the CAI strength were measured at 1.72 kJ m−2 at 35.2 GPa respectively.
Blind faith: fact, fiction and fraud in public controversy over science
Authors: Hagendijk Rob , Meeus Jan
Published: August 2002

Constructivist approaches have flourished in both science studies and media studies during the 1980s. Although similar perspectives are used in these fields to study the production of non-fictional texts, there is little exchange and integration on a theoretical level. This article uses the Buck-Goudsmit Affair to explore an integrated constructivisit approach to public controversy over science. The Buck-Goudsmit Affair is a public controversy in the Netherlands that started in 1990 over a claim about a possible cure against AIDS. It is argued that the public understanding of the controversy can be analysed in terms of a `meta-narrative' structure which accounts for facts, processes and identities of those involved. This `meta-narrative' structure of the developing controversy can be reconstrued on the basis of the texts that make up the textual corpus of the controversy. Various sorts of non-fictional text play a role in public controversy, for example, scientific texts, journalistic texts and legal and administrative documents. Texts belonging to these various genres differ in the ways in which the `factuality' and the `trustworthiness' of the text is established. The `meta-narrative' or public understanding of the controversy results from the ways in which texts refer to other texts in establishing facts, identities of actors and accounts. The interactions between texts belonging to different genres reflect the dynamics of journalism, science and the law. Blind faith and trust in texts from other actors and other domains appear to be more important in bringing about changes in the way in which the controversy is understood than solid proof or independent hard facts.
Media (mis)communication on the science of climate change
Authors: Bell Allan
Published: August 2002

Climate change has been widely reported as a scientific and environmental issue. In six months' news coverage of climate change in New Zealand, reporting of basic scientific facts was overwhelmingly accurate. News sources rated over 80% of stories no worse than slightly inaccurate. However, one story in six contained significant misreporting. Some stories overstated the advance of climate change or confused ozone depletion and the greenhouse effect. Scientific sources rated coverage overall worse than their own individual judgments showed it to be. Examination of ways in which stories came about leads to recommendations on how scientists and journalists can work together to better inform the public about climate change.
Adolescents and animal research: stable attitudes or ephemeral opinions?
Authors: Pifer Linda Kimmel
Published: August 2002

This study examines the relative stability of adolescent attitudes towards animal research, using data from the Longitudinal Study of American Youth (LSAY). The majority of adolescents were found to have either uncertain or unstable attitudes towards animal research. Five groups of students were studied: consistent supporters of animal research, consistent opponents of animal research, those who were uncertain about their position, those who moved from support to opposition, and those who moved from opposition to support. The greatest distinguishing feature between opponents and supporters of animal research was gender. Opponents of animal research were predominantly female, while supporters were predominantly male. The study also examined the relationship between attitudes towards animal research and science achievement, science course enrolment, parent education, environmental interest, and feminism.
An ethical risk communication protocol for science and mass communication
Authors: Valenti JoAnn , Wilkins Lee
Published: August 2002

This paper explores the philosophical foundations of risk communication, develops a protocol for ethical risk communication to be used by scientists, journalists and public relations practitioners, and applies the protocol to two cases of risk communication. We argue that the goals of risk communication are firstly to do no harm, and secondly to promote a public dialogue about risk. After outlining the philosophical foundation for these goals, we develop the protocol which will allow both the creators and the recipients of risk communication messages to evaluate their content. The protocol focuses on questions of accuracy, context, mobilizing information, and public environmental literacy.
The UK National Consensus Conference on Plant Biotechnology
Authors: Joss Simon , Durant John
Published: August 2002

We consider the consensus conference as a model for the incorporation of lay perspectives within the assessment of new sciences and technologies. A consensus is a forum in which a group of laypeople questions experts about a controversial scientific or technological subject, assesses the experts' responses, reaches a consensus about the subject, and reports its conclusions at a press conference. Following a brief description of the development of consensus conferences in Denmark, we review the organization and the outcome of the first UK National Consensus Conference on Plant Biotechnology (UKNCC). The UKNCC is currently the subject of a detailed evaluation. At this stage, we are principally concerned to provide practical information about the organization of the conference. However, we also offer a preliminary assessment of the potential significance of this novel approach for the public understanding of science.
Constructing climate change: claims and frames in US news coverage of an environmental issue
Authors: Trumbo Craig
Published: August 2002

An empirical content analysis of a decade of coverage of climate change in five national newspapers in the US is presented. The analysis is based on the perspective, drawn from social problems theory, that the content of news discourse can be understood in terms of claims-making and framing. Climate change is also discussed in terms of Downs' issue-attention cycle, a five-stage model describing the rise and fall of social attention to important issues. Climate change, as a news story, is described as exhibiting three phases that are related to the sources quoted and the frames presented in the news coverage. Results of the analysis show that scientists tend to be associated with frames emphasizing problems and causes, while politicians and special interests tend to be associated with frames emphasizing judgments and remedies. Results also show how scientists declined as news sources as the issue became increasingly politicized.
The Boffin: a stereotype of scientists in post-war British films (1945-1970)
Authors: Jones Robert A.
Published: August 2002

The period between 1945 and 1970 was critical for the public reputation of British science. It was also a golden age for British cinema. Feature films of this period are used in this paper as a tool for investigating the public image of the scientist. Three main stereotypes are identified, but one of these, which I have called `the Boffin' forms the main focus of the paper. `Boffins' are scientists working with the government and/or armed forces in wartime. An analysis of the portrayal of Barnes Wallis in The Dam Busters provides the main characteristics of the stereotype, and fictional Boffins from other films are compared with this. The origins of the stereotype are traced to the actual situation of scientists in the British war effort, and to class and cultural divisions in post-war Britain. The persistence of the stereotype is also discussed. The implications of this analysis for our understanding of public attitudes to scientists during this period are considered.
Training and development for informal science learning
Authors: Crockett Jane Randall
Published: August 2002

This exploratory study assessed the need for training and development of both administrators and education directors working in informal learning environments in the United States. Further, the study identified useful and feasible methods to meet these needs. Finally, it suggested that informal science learning is understood as a collective entity.

This study triangulated, or coordinated, various research and data analysis methods to provide a more effective base for understanding the proposed activities. Phase 1 consisted of interviewing persons knowledgeable about informal science learning. These data were analysed qualitatively and used to develop the Phase 2 survey, which was administered to practitioners in these environments. Data from the Phase 2 survey were measured quantitatively.

Although results suggest that some kind of training is necessary for administrators, significantly more people strongly agree that education directors need training specifically oriented towards informal science learning. Training for either administrators or education directors should include development of the following skills and attributes: personnel skills, fund-raising skills, financial skills, enthusiasm about doing science with others, knowledge of diverse publics, ability to interact with diverse publics, and volunteer interaction skills.

Data indicate that several methods would be very useful and feasible for training both administrators and education directors. These methods include: on-the-job training, a yearly one-week training activity, a degree program in a related field combined with a specific internship, and a series of training courses or seminars.

Data suggest that informal science learning can be understood as a collective entity using descriptors such as: industry, field, profession and discipline. However, this study suggests that using environmental characteristics of informal science learning contexts (instead of conceptualising them as the opposite of formal education) may be valuable for better understanding these environments. This understanding might increase the attention given to informal science learning environments as integral components in a holistic view of human learning.
Public attitudes to gene technology: the case of the MacGregor's® tomato
Authors: Schibeci Renato , Barns Ian , Kennealy Shona , Davison Aidan
Published: August 2002

This paper reports the pilot phase of a three-year project, `Public perceptions of biotechnology', conducted in Perth, Western Australia. The purposes of this pilot investigation were (1) to develop a computer-based method for investigating public perceptions of biotechnology, and (2) to report the perceptions of four `interested publics' about the Flavr Savr™/MacGregor's® tomato, a genetically engineered tomato. By `interested publics' we mean members of groups who are not experts in the field, but have an interest because of their membership of the group. We developed a computer-based database of information about this tomato to stimulate, in interviews, respondents' articulation of their knowledge and perceptions of biotechnology. The database was a multimedia package, based on a HyperCard stack on a Macintosh PowerBook 180C, with information about the tomato in ten different categories. The data suggest that our methodology has the potential to provide a fruitful approach to exploring the background knowledges and perceptions of different publics.
Kaleidoscoping public understanding of science on hygiene, health and plague: a survey in the aftermath of a plague epidemic in India
Authors: Raza Gauhar , Dutt Bharvi , Singh Surjit
Published: August 2002

In September 1994 a plague epidemic hit a number of cities in India. Though the spread of the disease was controlled within a short period of about one month, its influences on various channels of information, on the functioning of government departments (especially health and sanitation), on the scientific community and on people's scientific information level were remarkable. This paper analyses the responses of 1127 individuals interviewed in December 1994. The data indicates high levels of informedness about health, hygiene and plague, with little reference to extra-scientific explanations of the causes of the epidemic. Respondents expressed a high degree of confidence in the modern system of medicine. From this analysis we also infer that the public could not be described as `superstitious', `unscientific' or `unhygienic': only when denied access to information and civic amenities did they show extra-scientific thinking or `unhygienic' behaviour.
Unwinding of Continuous Medicaid Coverage Among Patients at Community Health Centers
Authors: Bensken Wyatt P. , Koroukian Siran M. , McGrath Brenda M. , Alberti Philip M. , Cottrell Erika K. , Sills Marion R.
Published: January 2024

This retrospective cohort study uses data from the Accelerating Data Value Across a National Community Health Center Network to assess patterns of Medicaid disenrollment during the first 6 months after the end of continuous enrollment.
Design of Fatigue‐Resistant Hydrogels
Authors: Han Zilong , Lu Yuchen , Qu Shaoxing
Published: January 2024

Hydrogels are made tough to resist crack propagation. However, for seamless integration into devices and machines, it necessitates robustness against cyclic loads. Central to this objective is enhancing fatigue resistance, an indispensable attribute facilitating the optimal performance of hydrogels within a multitude of biological contexts, spanning various plant and animal tissues, as well as diverse biomedical and engineering areas. In this review, recent research concerning the fatigue behavior of hydrogels, presenting a comprehensive consolidation of the inherent mechanisms that underpin diverse strategies aimed at fortifying fatigue resistance, is summarized. A critical facet in the architectural blueprint of fatigue‐resistant hydrogels is emphasized, involving the imposition of spatial constraints upon the main chains at the crack tips, thereby effectuating a protracted delay in their fracture initiation during prolonged cyclic loading. The integration of multiscale mechanisms encompassing networks, interactions, media, and structures stands as a pivotal factor in the design of fatigue‐resistant hydrogels. It is hoped that the review will considerably propel the pragmatic deployment of fatigue‐resistant hydrogels across a diverse array of applications, thus catalyzing advancements in multiple fields.
Revealing the Substrate Constraint Effect on the Thermodynamic Behaviour of the Pd–H through Capacitive‐Based Hydrogen‐Sorption Measurement
Authors: Kim Gwangmook , Lee Soomin , Lee Sang‐kil , Yu Han Jun , Cho Hunyoung , Chung Youngjun , Park Tae‐Eon , Lee Hyun‐Sook , Shim Wooyoung , Lee Kyu Hyoung , Park Jeong Young , Kim Yu Jin , Chun Dong Won , Lee Wooyoung
Published: January 2024

Mechanical constraints imposed on the Pd–H system can induce significant strain upon hydrogenation‐induced expansion, potentially leading to changes in the thermodynamic behavior, such as the phase‐transition pressure. However, the investigation of the constraint effect is often tricky due to the lack of simple experimental techniques for measuring hydrogenation‐induced expansion. In this study, a capacitive‐based measurement system is developed to monitor hydrogenation‐induced areal expansion, which allows us to control and evaluate the magnitude of the substrate constraint. By using the measurement technique, the influence of substrate constraint intensity on the thermodynamic behavior of the Pd–H system is investigated. Through experiments with different constraint intensities, it is found that the diffefrence in the constraint intensity minimally affects the phase‐transition pressure when the Pd–H system allows the release of constraint stress through plastic deformation. These experiments can improve the understanding of the substrate constraint behaviours of Pd–H systems allowing plastic deformation while demonstrating the potential of capacitive‐based measurement systems to study the mechanical–thermodynamic coupling of M–H systems.
Anti‐Fatigue Tandem Organic Photovoltaics for Indoor Illumination
Authors: Li Hao , Zheng Zhong , Yang Shiwei , Wang Tao , Yang Yi , Tang Yanjie , Zhang Shaoqing , Hou Jianhui
Published: January 2024

The ability of achieving high efficiency makes tandem organic photovoltaics (PVs) a competitive technique in potential indoor applications. Except high efficiency, reliable indoor energy supply also calls for outstanding stability. However, unavoidable unstable voltage supply from the circuit control system for indoor light sources like light emitting diodes (LED) and incandescent lamps would cause carrier density fluctuation and device fatigue driven by periodic light/dark switching. In this work, the strobing‐induced fatigue within the bulk heterojunction (BHJ)/interconnecting layer (ICL) interface is first revealed and overcome. Based on reliable and effective interfacial doping between conjugated acceptor and metal oxide, the interfacial capacitance that determines the strobing‐induced fatigue, has been significantly restrained. The imbalance carrier migration and fierce inter‐layer accommodating during the burn‐in stage caused by light strobing are substantially diminished. Benefit from this method, the stability of tandem devices is highly enhanced under strobing indoor illumination, and a champion efficiency (35.02%) is obtained. The method provides guidance for further material design for interconnecting layers in organic photovoltaics.
Injectable MSC Spheroid and Microgel Granular Composites for Engineering Tissue
Authors: Caprio Nikolas Di , Davidson Matthew D. , Daly Andrew C. , Burdick Jason A.
Published: January 2024

Many cell types require direct cell–cell interactions for differentiation and function; yet, this can be challenging to incorporate into 3‐dimensional (3D) structures for the engineering of tissues. Here, a new approach is introduced that combines aggregates of cells (spheroids) with similarly‐sized hydrogel particles (microgels) to form granular composites that are injectable, undergo interparticle crosslinking via light for initial stabilization, permit cell–cell contacts for cell signaling, and allow spheroid fusion and growth. One area where this is important is in cartilage tissue engineering, as cell–cell contacts are crucial to chondrogenesis and are missing in many tissue engineering approaches. To address this, granular composites are developed from adult porcine mesenchymal stromal cell (MSC) spheroids and hyaluronic acid microgels and simulations and experimental analyses are used to establish the importance of initial MSC spheroid to microgel volume ratios to balance mechanical support with tissue growth. Long‐term chondrogenic cultures of granular composites produce engineered cartilage tissue with extensive matrix deposition and mechanical properties within the range of cartilage, as well as integration with native tissue. Altogether, a new strategy of injectable granular composites is developed that leverages the benefits of cell–cell interactions through spheroids with the mechanical stabilization afforded with engineered hydrogels.
Accounting for costs in attainable‐region‐based reactor–separation network synthesis: Models, tradeoffs, and insights
Authors: Pastore de Lima Arthur E. , Ryu Joonjae , Maravelias Christos T.
Published: January 2024

In reaction engineering, the attainable region defines the set of all possible states attainable in the outlet stream of any steady‐state reactor network, given specified feed and reaction kinetics. Costs in approaches that aim to determine the attainable region are often neglected, resulting in targets that require expensive processes. In this work, we propose modeling methods that allow us to account for costs in reactor–separation synthesis while accurately identifying the attainable region. Our goal is to holistically analyze cost trade‐offs within the attainable region as well as provide a method to obtain practical targets to be used as benchmarks. We generate the attainable region using the continuous stirred tank reactor (CSTR) equivalence principle and introduce separation models accounting for costs to perform the required separation tasks. Through several case studies, we show how some subregions, typically close to the attainable region boundary, are expensive to achieve.
Human‐like enamel growth in Homo naledi
Authors: Mahoney Patrick , McFarlane Gina , Taurozzi Alberto J. , Madupe Palesa P. , O'Hara Mackie C. , Molopyane Keneiloe , Cappellini Enrico , Hawks John , Skinner Matthew M. , Berger Lee
Published: January 2024

Objectives

A modern pattern (rate and duration) of dental development occurs relatively recently during human evolution. Given the temporal overlap of Homo naledi with the first appearance of fossil Homo sapiens in Africa, this small‐bodied and small‐brained hominin presents an opportunity to elucidate the evolution of enamel growth in the hominin clade. Here we conduct the first histological study of two permanent mandibular canines and one permanent maxillary first molar, representing three individuals attributed to H. naledi. We reconstruct the rate and duration of enamel growth and compare these findings to those reported for other fossil hominins and recent humans.

Materials and Methods

Thin sections of each tooth were produced using standard histological methods. Daily and longer period incremental markings were measured to reconstruct enamel secretion and extension rates, Retzius periodicity, canine crown and molar cusp formation time.

Results

Daily enamel secretion rates overlapped with those from recent hominins. Canine crown formation time is similar to that observed in recent Europeans but is longer than canine formation times reported for most other hominins including Australopithecus and H. neanderthalensis. The extended period of canine formation appears to be due to a relatively tall enamel crown and a sustained slow rate of enamel extension in the cervical portion of the crown. A Retzius periodicity of 11 days for the canines, and nine days for the molar, in H. naledi parallel results found in recent humans. An 11‐day periodicity has not been reported for Late Pleistocene Homo (H. erectus, H. neanderthalensis) and is rarely found in Australopithecus and Paranthropus species.

Discussion

Enamel growth of H. naledi is most similar to recent humans though comparative data are limited for most fossil hominin species. The high Retzius periodicity values do not follow expectations for a small‐brained hominin.
All‐Round Ionic Liquids for Shuttle‐Free Zinc‐Iodine Battery
Authors: Xiao Tao , Yang Jin‐Lin , Zhang Bao , Wu Jiawen , Li Jinliang , Mai Wenjie , Fan Hong Jin
Published: January 2024

The practical implementation of aqueous zinc‐iodine batteries (ZIBs) is hindered by the rampant Zn dendrites growth, parasite corrosion, and polyiodide shuttling. In this work, ionic liquid EMIM[OAc] is employed as an all‐round solution to mitigate challenges on both the Zn anode and the iodine cathode side. First, the EMIM+ embedded lean‐water inner Helmholtz plane (IHP) and inert solvation sheath modulated by OAc− effectively repels H2O molecules away from the Zn anode surface. The preferential adsorption of EMIM+ on Zn metal facilitates uniform Zn nucleation via a steric hindrance effect. Second, EMIM+ can reduce the polyiodide shuttling by hindering the iodine dissolution and forming an EMIM+‐I3− dominated phase. These effects holistically enhance the cycle life, which is manifested by both Zn || Zn symmetric cells and Zn‐I2 full cells. ZIBs with EAc deliver a capacity decay rate of merely 0.01 ‰ per cycle after over 18,000 cycles at 4 A g−1, and lower self‐discharge and better calendar life than the ZIBs without ionic liquid EAc additive.
Polydentate Ligand Reinforced Chelating to Stabilize Buried Interface toward High‐Performance Perovskite Solar Cells
Authors: Liu Baibai , Zhou Qian , Li Yong , Chen Yu , He Dongmei , Ma Danqing , Han Xiao , Li Ru , Yang Ke , Yang Yingguo , Lu Shirong , Ren Xiaodong , Zhang Zhengfu , Ding Liming , Feng Jing , Yi Jianhong , Chen Jiangzhao
Published: January 2024

The instability of the buried interface poses a serious challenge for commercializing perovskite photovoltaic technology. Herein, we report a polydentate ligand reinforced chelating strategy to strengthen the stability of buried interface by managing interfacial defects and stress. The bis(2,2,2‐trifluoroethyl) (methoxycarbonylmethyl)phosphonate (BTP) is employed to manipulate the buried interface. The C=O, P=O and two −CF3 functional groups in BTP synergistically passivate the defects from the surface of SnO2 and the bottom surface of the perovskite layer. Moreover, The BTP modification contributes to mitigated interfacial residual tensile stress, promoted perovskite crystallization, and reduced interfacial energy barrier. The multidentate ligand modulation strategy is appropriate for different perovskite compositions. Due to much reduced nonradiative recombination and heightened interface contact, the device with BTP yields a promising power conversion efficiency (PCE) of 24.63 %, which is one of the highest efficiencies ever reported for devices fabricated in the air environment. The unencapsulated BTP‐modified devices degrade to 98.6 % and 84.2 % of their initial PCE values after over 3000 h of aging in the ambient environment and after 1728 h of thermal stress, respectively. This work provides insights into strengthening the stability of the buried interface by engineering multidentate chelating ligand molecules.
Succinic acid production from softwood with genome‐edited Corynebacterium glutamicum using the CRISPR‐Cpf1 system
Authors: Lee Dae‐Seok , Cho Eun Jin , Nguyen Dinh‐Truong , Song Younho , Chang Jihye , Bae Hyeun‐Jong
Published: January 2024

Corynebacterium glutamicum is a useful microbe that can be used for producing succinic acid under anaerobic conditions. In this study, we generated a knock‐out mutant of the lactate dehydrogenase 1 gene (ΔldhA‐6) and co‐expressed the succinic acid transporter (Psod:SucE‐ ΔldhA) using the CRISPR‐Cpf1 genome editing system. The highly efficient HPAC (hydrogen peroxide and acetic acid) pretreatment method was employed for the enzymatic hydrolysis of softwood (Pinus densiflora) and subsequently utilized for production of succinic acid.

Upon evaluating a 1%–5% hydrolysate concentration range, optimal succinic acid production with the ΔldhA mutant was achieved at a 4% hydrolysate concentration. This resulted in 14.82 g L−1 succinic acid production over 6 h. No production of acetic acid and lactic acid was detected during the fermentation. The co‐expression transformant, [Psod:SucE‐ΔldhA] produced 17.70 g L−1 succinic acid in 6 h. In the fed‐batch system, 39.67 g L−1 succinic acid was produced over 48 h. During the fermentation, the strain consumed 100% and 73% of glucose and xylose, respectively. The yield of succinic acid from the sugars consumed was approximately 0.77 g succinic acid/g sugars. These results indicate that the production of succinic acid from softwood holds potential applications in alternative biochemical processes.
A versatile method for conjugating lipid nanoparticles on T cells through combination of click chemistry and metabolic glycoengineering
Authors: Li Xin , Weller Sven , Clergeaud Gael , Andresen Thomas L.
Published: January 2024

Cell‐mediated drug delivery by conjugating nanomedicine to the surface of living cells is a promising strategy for enhancing the efficacy of both drug delivery and cell therapy. It exploits the tissue homing properties of the specific cell types to overcome in vivo barriers and forms a drug depot by directly putting the therapeutic payload in target cells. An important concern of developing this system is the method to conjugate nanoparticles on cells. Herein, we developed a bioorthogonal T cell conjugation strategy using SPAAC click chemistry, which allows controllable and highly efficient conjugation without affecting the viability and functions of the cytotoxic T lymphocytes. Azide groups were incorporated on the surface of T cells through metabolic glycoengineering, followed by reacting with dibenzylcyclooctyne (DBCO) modified lipid nanoparticles (LNPs). LNPs can be conjugated to T cells, allowing for the loading of different drug molecules on the cells. The metabolic engineering and click reaction approach provides a simple and versatile strategy to conjugate NPs to living cells and enable the development of sophisticated therapeutic cell products.
Comprehensive characterization of PKHD1 mutation in human colon cancer
Authors: Han Lu , Gong Fangming , Wu Xuxiaochen , Tang Wanxiangfu , Bao Hua , Wang Yue , Wang Daizhenru , Sun Yulan , Li Peng
Published: January 2024

Introduction

The PKHD1 (Polycystic Kidney and Hepatic Disease 1) gene is essential for producing fibrocystin or polyductin, which is crucial in various cellular functions. Mutations in PKHD1 have been found to be involved in the development and progression of colorectal cancer (CRC). Along with APC, TP53, and KRAS, PKHD1 is one of the most frequently mutated genes in CRC. PKHD1 expression is governed by the Wnt/PCP pathway, often dysregulated in CRC. Targeting this pathway, crucial for CRC progression, could unveil potential therapeutic strategies for colon cancer treatment.

Methods

This study examined an in‐house dataset of 3702 colon cancer samples, analyzing mutation landscapes, clinical features, tumor mutational burden (TMB), microsatellite instability (MSI), and chromosomal instability (CIN) score. For the survival analysis of PKHD1 patients, survival data of 436 colon adenocarcinoma samples were obtained from TCGA dataset. Additionally, 433 samples from TCGA with RNA‐seq data were used for the assessment of immune cell infiltration and gene set enrichment analysis.

Results

Polycystic Kidney and Hepatic Disease 1 mutation was detected in 424 colon cancer patients from our in‐house cohort and was associated with increased TMB, higher MSI, and lower CIN score. Importantly, within the TCGA dataset, PKHD1 mutations were identified as an independent prognostic factor, not merely correlated with established prognostic biomarkers, and were associated with poorer overall survival outcomes. In terms of immune response, these mutations correlated with increased enrichment scores for 12 immune cell types, including B cell plasma, macrophages, and naive CD4+ T cells. Additionally, interferon alpha and interferon‐gamma gene sets were significantly down‐regulated in patients with PKHD1 mutations (FDA q‐value < 0.1).

Conclusions

Overall, these findings suggest that PKHD1 may be a potential biomarker for the prognosis of colon cancer and provide some insight for personalized immunotherapy.
Bougainvillea glabra Choisy bracts extract in free and liposomal forms reduce hyperplasia induced by let‐60gain‐of‐function in Caenorhabditis elegans
Authors: de Oliveira Pereira Flávia Suelen , Oliveira de Souza Maria Eduarda , Viçozzi Gabriel Pedroso , Caurio Aline Castro , Pinton Simone , Denardin Cristiane Casagrande , Haas Sandra Elisa , Gasparotto Denardin Elton Luis , Ávila Daiana Silva
Published: January 2024

In this study, we evaluated the toxicological and antiproliferative effects of B. glabra Choisy bract extract (BGCE) in its free and loaded into liposomes forms administered to C. elegans mutants with let‐60 gain‐of‐function (gf). Our results demonstrated that the concentration up to 75 μg CAE/mL of BGCE was safe for the worms. Notably, we developed BGCE‐loaded liposomes to extend the pharmacological window up to 100 μg CAE/mL without toxicity. In addition, the extract and liposomes reduced the number and area of the multivulva formed in let‐60 gf mutants. There was also an increase in the apoptotic signaling in the germline cells and increased longevity mediated through DAF‐16 nuclear translocation with GST‐4 activation in the treated animals. Our findings demonstrated that the BGCE‐loaded liposomes possess antitumoral effects due to the activation of the apoptotic signaling and DAF‐16 nuclear translocation.
Perfluoralkyl/Rose Bengal Functionalized Janus Silica Nanoparticles for Photocatalytic Transformations with Singlet Oxygen
Authors: Pourshiani Omid , Romero Zeno , Ganji Nasim , Herrendorf Tim , Seifert Andreas , Demchenko Anna , Prosenc Marc H. , Kleist Wolfgang , Kopnarski Michael , Karimi Babak , Thiel Werner R.
Published: January 2024

A Janus mesoporous silica material with an imidazolium‐based ionic liquid and perflouroalkyl motifs was synthesized using hollow Stöber particles. Its morphology, chemical composition and surface properties were characterized by N2 physisorption analysis, scanning and transmission electron microscopy, elemental mapping, thermogravimetric and elemental analysis, and solid state NMR spectroscopy. The Janus nanoparticles have independent faces with fluorophilic and hydrophilic properties suitable for interaction with oxygen and Rose Bengal, which is a known photosensitizer for singlet oxygen generation. The catalytic activity of these Janus particles was evaluated in a series of transformations using singlet oxygen. They provide the desired products in high yield and selectivity.
Zirconia‐containing glass‐ceramics: From nucleating agent to primary crystalline phase
Authors: Shearer Adam , Montazerian Maziar , Deng Binghui , Sly Jessica J. , Mauro John C.
Published: January 2024

This article reviews promising studies on the design, manufacturing, microstructure, properties, and applications of glass‐ceramics containing ZrO2 and relevant glass‐ceramic matrix composites. After the addition of ZrO2 to a glass‐ceramic composition, it can persist in the residual glassy phase, facilitate nucleation, and/or precipitate as ZrO2 or another zirconate crystalline phase. Also, ZrO2‐reinforced or ZrO2‐toughened glass‐ceramics can be designed as composites. In this article, the term “ZrO2‐containing glass‐ceramics” encompasses all these scenarios in which ZrO2 is present. Such glass‐ceramics offer a wide range of applications in modern industries, including but not limited to architecture, optics, dentistry, medicine, and energy. Since S. Donald Stookey's discovery of glass‐ceramics in the early 1950s, the most important scientific efforts reported in the literature are reviewed. ZrO2 is commonly added to glass‐ceramics to promote nucleation. As a result, the role of ZrO2 in structural modification of residual glass and stimulating the nucleation in glass‐ceramic is first discussed. ZrO2 can also be designed into the main crystalline phase of glass‐ceramics, contributing achieving super high fracture toughness above 4 MPa·m0.5. Experimental and computational studies are reviewed in detail to elucidate how the transformation toughening and other mechanisms help to achieve such high values of fracture toughness. Sintered and glass‐ceramic matrix composites also show promise, where ZrO2 contributes to improved stability and mechanical properties. Finally, we hope this article will provoke interest in glass‐ceramic materials in both the scientific and industrial communities so that their tremendous technological potential in developing, for example, tough, thermally stable, transparent, and biologically compatible materials can be realized more widely.
Nickel Carbide Nanoparticle Catalyst for Selective Hydrogenation of Nitriles to Primary Amines
Authors: Yamaguchi Sho , Kiyohira Daiki , Tada Kohei , Kawakami Taiki , Miura Akira , Mitsudome Takato , Mizugaki Tomoo
Published: January 2024

Despite its unique physicochemical properties, the catalytic application of nickel carbide (Ni3C) in organic synthesis is rare. In this study, we report well‐defined nanocrystalline Ni3C (nano‐Ni3C) as a highly active catalyst for the selective hydrogenation of nitriles to primary amines. The activity of the aluminum‐oxide‐supported nano‐Ni3C (nano‐Ni3C/Al2O3) catalyst surpasses that of Ni nanoparticles. Various aromatic and aliphatic nitriles and dinitriles were successfully converted to the corresponding primary amines under mild conditions (1 bar H2 pressure). Furthermore, the nano‐Ni3C/Al2O3 catalyst was reusable and applicable to gram‐scale experiments. Density functional theory calculations suggest the formation of polar hydrogen species on the nano‐Ni3C surface, which were attributed to the high activity of nano‐Ni3C towards nitrile hydrogenation. This study demonstrates the utility of metal carbides as a new class of catalysts for liquid‐phase organic reactions.