bluuebunny/crossref_metadata_2025 huggingface dataset:
Synchronous Ensembles of Hippocampal CA1 Pyramidal Neurons Associated with Theta but not Ripple Oscillations During Novel Exploration
Authors: Chen En-Li , Chen Tsai-Wen , Schreiter Eric R. , Lin Bei-Jung
Published: April 2024

Synchronous neuronal ensembles play a pivotal role in the consolidation of long-term memory in the hippocampus. However, their organization during the acquisition of spatial memory remains less clear. In this study, we used neuronal population voltage imaging to investigate the synchronization patterns of CA1 pyramidal neuronal ensembles during the exploration of a new environment, a critical phase for spatial memory acquisition. We found synchronous ensembles comprising approximately 40% of CA1 pyramidal neurons, firing simultaneously in brief windows (∼25ms) during immobility and locomotion in novel exploration. Notably, these synchronous ensembles were not associated with ripple oscillations but were instead phase-locked to local field potential theta waves. Specifically, the subthreshold membrane potentials of neurons exhibited coherent theta oscillations with a depolarizing peak at the moment of synchrony. Among newly formed place cells, pairs with more robust synchronization during locomotion displayed more distinct place-specific activities. These findings underscore the role of synchronous ensembles in coordinating place cells of different place fields.
Recording γ-secretase activity in living mouse brains
Authors: Hou Steven S. , Ikegawa Yuya , Kwon Yeseo , Houser Mei C.Q. , Lundin Brianna , Bacskai Brian J. , Berezovska Oksana , Maesako Masato
Published: April 2024

γ-Secretase plays a pivotal role in the central nervous system. Our recent development of genetically encoded Förster resonance energy transfer (FRET)-based biosensors has enabled the spatiotemporal recording of γ-secretase activity on a cell-by-cell basis in live neurons
in culture
. Nevertheless, how γ-secretase activity is regulated
in vivo
remains unclear. Here we employ the near-infrared (NIR) C99 720-670 biosensor and NIR confocal microscopy to quantitatively record γ-secretase activity in individual neurons in living mouse brains. Intriguingly, we uncovered that γ-secretase activity may influence the activity of γ-secretase in neighboring neurons, suggesting a potential “cell non-autonomous” regulation of γ-secretase in mouse brains. Given that γ-secretase plays critical roles in important biological events and various diseases, our new assay
in vivo
would become a new platform that enables dissecting the essential roles of γ-secretase in normal health and diseases.
Khdc3 Regulates Metabolism Across Generations in a DNA-Independent Manner
Authors: Senaldi Liana , Hassan Nora , Cullen Sean , Balaji Uthra , Trigg Natalie , Gu Jinghua , Finkelstein Hailey , Phillips Kathryn , Conine Colin , Smith-Raska Matthew
Published: April 2024

Genetic variants can alter the profile of heritable molecules such as small RNAs in sperm and oocytes, and in this manner ancestral genetic variants can have a significant effect on offspring phenotypes even if they are not themselves inherited. Here we show that wild type female mice descended from ancestors with a mutation in the mammalian germ cell gene
Khdc3
have hepatic metabolic defects that persist over multiple generations. We find that genetically wild type females descended from
Khdc3
mutants have transcriptional dysregulation of critical hepatic metabolic genes, which persist over multiple generations and pass through both female and male lineages. This was associated with dysregulation of hepatically-metabolized molecules in the blood of these wild type mice with mutational ancestry. The oocytes of
Khdc3
-null females, as well as their wild type descendants, had dysregulation of multiple small RNAs, suggesting that these epigenetic changes in the gametes transmit the phenotype between generations. Our results demonstrate that ancestral mutation in
Khdc3
can produce transgenerational inherited phenotypes, potentially indefinitely.
The domesticated transposon protein L1TD1 associates with its ancestor L1 ORF1p to promote LINE-1 retrotransposition
Authors: Kavaklıoğlu Gülnihal , Podhornik Alexandra , Vcelkova Terezia , Marjanovic Jelena , Beck Mirjam A , Phan-Canh Trinh , Mair Theresia , Miccolo Claudia , Drino Aleksej , Doni Mirko , Egger Gerda , Chiocca Susanna , Modic Miha , Seiser Christian
Published: April 2024

Repression of retrotransposition is crucial for the successful fitness of a mammalian organism. The domesticated transposon protein L1TD1, derived from LINE-1 (L1) ORF1p, is an RNA-binding protein that is expressed only in some cancers and early embryogenesis. In human embryonic stem cells, it is found to be essential for maintaining pluripotency. In cancer, L1TD1 expression is highly correlative with malignancy progression and as such considered a potential prognostic factor for tumors. However, its molecular role in cancer remains largely unknown. Our findings reveal that DNA hypomethylation induces the expression of L1TD1 in HAP1 human tumor cells. L1TD1 depletion significantly modulates both the proteome and transcriptome and thereby reduces cell viability. Notably, L1TD1 associates with L1 transcripts and interacts with L1 ORF1p protein, thereby facilitating L1 retrotransposition. Our data suggest that L1TD1 collaborates with its ancestral L1 ORF1p as an RNA chaperone, ensuring the efficient retrotransposition of L1 retrotransposons, rather than directly impacting the abundance of L1TD1 targets. In this way, L1TD1 might have an important role not only during early development but also in tumorigenesis.
Thymic dendritic cell-derived IL-27p28 promotes the establishment of functional bias against IFN-γ production in newly generated CD4+ T cells through STAT1-related epigenetic mechanisms
Authors: Zhang Jie , Tang Hui , Wu Haoming , Pang Xuewen , Jin Rong , Zhang Yu
Published: April 2024

The newly generated CD4 single-positive (SP) T lymphocytes are featured by enhanced IL-4 but repressed IFN-γ production. The mechanisms underlying this functional bias remain elusive. Previous studies have reported that CD4
+
T cells from mice harboring DC-specific deletion of IL-27p28 display an increased capacity of IFN-γ production upon TCR stimulation. Here we demonstrated that similarly altered functionality occurred in CD4SP thymocytes, recent thymic emigrants (RTEs) as well as naive T cells from either

Cd11c-p28
f/f

mice or mice deficient in the α subunit of IL-27 receptor. Therefore, DC-derived IL-27p28-triggered, IL-27Rα-mediated signal is critically involved in the establishment of functional bias against IFN-γ production during their development in the thymus. Epigenetic analyses indicated reduced DNA methylation of the
Ifng
locus and increased trimethylation of H3K4 at both
Ifng
and
Tbx21
loci in CD4SP thymcoytes from

Cd11c-p28
f/f

mice. Transcriptome profiling demonstrated that
Il27p28
ablation resulted in coordinated up-regulation of STAT1-activated genes. Concurrently, STAT1 was found to be constitutively activated. Moreover, we observed increased accumulation of STAT1 at the
Ifng
and
Tbx21
loci and a strong correlation between STAT1 binding and H3K4me3 modification of these loci. Of note,
Il27p28
deficiency exacerbated the autoimmune phenotype of

Aire
-/-

mice. Collectively, this study reveals a novel mechanism underlying the functional bias of newly generated CD4
+
T cells and the potential relevance of such a bias in autoimmunity.
Birnaviral Hijacking of Endosomal Membranes
Authors: Zanetti Flavia A. , Fernández Ignacio , Baquero Eduard , Guardado-Calvo Pablo , Dubois Sarah , Morel Etienne , Alfonso Victoria , Aguilera Milton O. , Celayes María E. , Polo Luis M. , Suhaiman Laila , Galassi Vanesa V. , Chiarpotti María V. , Allende Carolina , Rodríguez Javier M. , Castón José R. , Lijavetzky Diego , Taboga Oscar , Colombo María I. , Pópolo Mario G. Del , Rey Félix A. , Delgui Laura R.
Published: April 2024

Birnaviruses form a distinct class of double-stranded RNA (dsRNA) viruses characterized by the absence of a transcription-competent inner core particle. The early endosomes (EE) of cells infected with the infectious bursal disease virus (IBDV) - a prototypical birnavirus and an important avian pathogen - constitute a platform for viral replication. Here, we study the mechanism of birnaviral hijacking of EE membranes for this process. We demonstrate that the viral protein 3 (VP3) specifically binds to phosphatidylinositol-3-phosphate (PI3P) present in EE membranes. We identify the domain of VP3 involved in PI3P-binding and its role in viral replication. Finally, our molecular simulations results unveil a two-stage modular mechanism for VP3 association with EE. Firstly, the carboxy-terminal region of VP3 adsorbs to the membrane via non-specific electrostatic interactions. Then, in the second stage, the VP3 core seals the membrane engagement by specifically binding PI3P through its P2 domain, additionally promoting PI3P accumulation.
A modular platform to display multiple hemagglutinin subtypes on a single immunogen
Authors: Lamson Dana Thornlow , Mohamed Faez Amokrane Nait , Vu Mya , Maurer Daniel P. , Ronsard Larance , Lingwood Daniel , Schmidt Aaron G.
Published: April 2024

Next-generation influenza vaccines aim to elicit cross-reactive humoral responses to multiple influenza subtypes. Such increased breadth would not only improve seasonal vaccines but may afford ‘universal’ protection against influenza subtypes including those with pandemic potential. Here, we describe a “beads-on-a-string” (BOAS) immunogen, that tandemly links up to eight distinct hemagglutinin (HA) head domains from circulating and non-circulating influenzas. These BOAS are immunogenic in the murine model and elicit comparable serum responses to each individual component. Notably, we also find that BOAS elicit cross-reactive, and neutralizing responses to influenza subtypes not included in the immunizing immunogen. Furthermore, BOAS conjugation to protein-based ferritin nanoparticles does not significantly augment serum responses suggesting that our BOAS platform is sufficient for eliciting cross-reactive responses without off-target effects induced by the nanoparticle scaffold. This mix-and-match immunogen design strategy is a robust platform for eliciting responses to multiple influenza subtypes via a single immunogen, and a potential platform for other viral glycoproteins.
High-frequency terahertz stimulation alleviates neuropathic pain by inhibiting the pyramidal neuron activity in the anterior cingulate cortex of mice
Authors: Peng Wenyu , Wang Pan , Tan Chaoyang , Zhao Han , Chen Kun , Si Huaxing , Tian Yuchen , Lou Anxin , Zhu Zhi , Yuan Yifang , Wu Kaijie , Chang Chao , Wu Yuanming , Chen Tao
Published: April 2024

Neuropathic pain (NP) is caused by a lesion or disease of the somatosensory system and is characterized by abnormal hypersensitivity to stimuli and nociceptive responses to non-noxious stimuli, affecting approximately 7–10% of the general population. However, current first-line drugs like non-steroidal anti-inflammatory agents and opioids have limitations, including dose-limiting side effects, dependence, and tolerability issues. Therefore, developing new interventions for the management of NP is urgent. In this study, we discovered that the high-frequency terahertz stimulation (HFTS) at approximately 36 THz effectively alleviates NP symptoms in mice with spared nerve injury. Computational simulation suggests that the frequency resonates with the carbonyl group in the filter region of Kv1.2 channels, facilitating the translocation of potassium ions. In vivo and in vitro results demonstrate that HFTS reduces the excitability of pyramidal neurons in the anterior cingulate cortex likely through enhancing the voltage-gated K+ and also the leak K+ conductance. This research presents a novel optical intervention strategy with terahertz waves for the treatment of NP and holds promising applications in other nervous system diseases.
Comic innocence
Authors: Zijp Dick
Published: April 2024

In recent years, humour has re-entered the public sphere as a serious and potentially explosive topic of debate, giving rise to social conflicts and controversies. Paradoxically, however, humour has at the same time been passionately (and often aggressively) defended as innocent and harmless. I propose the notion of ‘comic innocence’ to make sense of this paradox. I take Dutch and American studies of racism, white innocence and racial ignorance as a starting point to construct a theory of comic innocence, which is tested through the analysis of responses in both legacy and social media to a serious opinion article on humour (written by the author of this paper), which sparked a scandal in the summer of 2021. I analyse 265 tweets and a small number of related newspaper articles and blog posts to demonstrate the respondents’ “humour ideologies”. I argue that, in the context of the “re-politicisation of humour”, those who defend humour as innocent mobilise and re-articulate three older ideas on humour. First, they emphasise the overall positive psychological, social and political functions and effects of humour. Second, they believe that humour should be protected against a ‘woke’ culture of high sensitivity and censorship. Third, they argue that humour research is a joke, and humour scholars lack a sense of humour. The humour scholar appears in this debate as the most important source of danger: a humourless, left-wing scientist keen on curtailing and censoring humorous expression.
General and Academic Vocabulary Sizes and Reading Comprehension among the First Year BSED English Students
Authors: Cawagdan-Cuarto Harieth , Cuenca Pia , Gonito Judy-Ann , Lyka Maan Kalaw
Published: April 2024

Proficiency in the English language comprises a wide range of skills, including listening, speaking, reading, and writing. Among these skills, reading comprehension holds particular importance as it enables students to effectively process and understand written text. An essential factor contributing to successful reading comprehension is vocabulary, which plays a fundamental role in the reading process. This study aimed to explore the relationship between reading comprehension and vocabulary, specifically focusing on general and academic vocabulary commonly used in English learning and academic settings. The research utilized a descriptive-correlational method, employing Pearson’s r method to establish a significant relationship between the two variables. The results revealed significant findings for each type of vocabulary and reading comprehension. The learners demonstrated a very high general vocabulary and an above-average academic vocabulary size.  Additionally, the learners exhibited an average level of reading comprehension. These statistical findings emphasize the significant relationship between the variables studied, emphasizing their mutual influence. To enhance students’ academic performance, the researchers suggest implementing modules comprising diverse activities and exercises to promote the development of both academic vocabulary and reading comprehension skills.
Constraints Faced by Farmers in Information Seeking in Bundelkhand Region of Uttar Pradesh
Authors: Singh Shubham , Sharma Purushottam , Bharati Arvindra Kumar , Vyas Dileep , Yadav Rishabh
Published: April 2024

This research was conducted with the objective of studying the constraints faced in information seeking by farmers in the Bundelkhand region of Uttar Pradesh. A sample of 210 respondents was randomly selected, and data were collected through a structured and pre-tested interview schedule. The gathered data were analyzed and tabulated to identify constraints related to information seeking in the study area. The findings highlighted various challenges faced by farmers, including issues such as the absence of information in the local language, lack of training, financial constraints, limited educational qualifications, restricted access to computers and information sources, insufficient electricity and internet availability, infrastructure deficiencies, inadequate community facilities, disorganized social structures, and the presence of an inferiority feeling. The study underscores the multifaceted nature of status of constraints faced by the farmers of Bundelkhand in Uttar Pradesh regarding accessing sources of information
Analyzing the Impact of Exchange Rates on Trade Performance in Tanzania: A VECM Approach
Authors: Hafidh Hafidh Ali , Soud Nahifa Said
Published: April 2024

This paper investigates the relationship between exchange rates and trade performance in Tanzania using a Vector Error Correction Model (VECM) analysis. The background discusses the importance of exchange rates in international trade and how fluctuating exchange rates can impact trade performance. The methodology section explains the research design, model specification, and estimation techniques employed, such as unit root tests, co-integration analysis, and VECM. The findings highlight a long-run positive relationship between exchange rates, foreign direct investment, GDP, and labor forces with trade performance, while inflation rate shows a negative impact. Granger causality tests reveal causal relationships between different variables and trade performance. The conclusions suggest policy recommendations for the government to enhance trade performance through fiscal and monetary policies and encourage further research in the field.
Cybersecurity Considerations for Smart Bangladesh: Challenges and Solutions
Authors: Sarker Sree Pradip Kumer , Khan Raza Zahir
Published: April 2024

Cybersecurity stands as a cornerstone for safeguarding the integrity, security, and prosperity of a nation in the digital era. It involves a multifaceted approach to protect interconnected digital systems, critical infrastructure, and sensitive data. In the context of a smart nation, where interconnected devices, sensors, and systems are integrated to enhance efficiency and quality of life, cybersecurity becomes even more crucial. As Bangladesh progresses towards its vision of becoming a Smart Nation, characterized by extensive integration of digital technologies into various sectors, cybersecurity emerges as a critical concern. The rapid digitization of infrastructure and services, driven by initiatives such as smart cities, e-governance, and digital healthcare, introduces new vulnerabilities and threats that must be addressed to safeguard against cyber-attacks and protect sensitive data. This paper explores the cybersecurity landscape of Bangladesh in the context of its Smart Nation aspirations, identifying key challenges and proposing solutions to mitigate risks. The cybersecurity challenges facing Smart Bangladesh initiatives are multifaceted and include inadequate cybersecurity policies, limited awareness and education, insufficient investment in cybersecurity infrastructure, and the proliferation of Internet of Things (IoT) devices with inherent vulnerabilities. These challenges expose smart systems to a range of threats, including malware and ransomware attacks, data breaches, insider threats, Distributed Denial of Service (DDoS) attacks, and IoT vulnerabilities. To address these challenges, stakeholders must adopt a proactive and multi-layered approach to cybersecurity. Recommendations include the development of comprehensive cybersecurity policies, enhanced public awareness and education campaigns, investment in cybersecurity infrastructure, implementation of secure-by-design principles in smart infrastructure development, and fostering public-private partnerships to share threat intelligence and resources. By prioritizing cybersecurity considerations and implementing robust cybersecurity measures, Bangladesh can build a resilient and secure digital ecosystem that supports its Smart Nation goals. However, addressing cybersecurity challenges requires coordinated efforts from government agencies, private sector organizations, academia, and civil society to create a cyber-resilient environment conducive to sustainable development and innovation. The author found this area of utmost interest and decided to delve deep into the aspects related to cybersecurity, in order to develop a well-designed journey towards a digitally transformed Bangladesh.
Exploring Determinants of Mortality among Adult PLHIV under ART at Meru Teaching and Referral Hospital, Kenya
Authors: Karimi Winfred , Gitunga Robert Muriungi , Onyambu Frank G , Gacheri Christine
Published: April 2024

HIV remains a persistent global health challenge, affecting the immune system and leading to significant morbidity and mortality despite advancements in antiretroviral therapy (ART). The study investigated the covariates that correspond to determinants linked to increased mortality among PLHIV (people living with HIV/AIDS) under ART at Meru Teaching and Referral Hospital (MTRH) over a five-year period. This retrospective cohort study utilized secondary data from hospital records between 2018 and 2022, focusing on demographic, socio-economic, and clinical variables. A logistic regression analysis was carried out to identify covariates that correspond to determinants linked to increased mortality among HIV-positive patients. The age range varied significantly, with a smaller percentage falling into younger age groups: 6.7% aged 18-25 years and 10.0% aged 26-35 years. The majority were middle-aged, with 24.9% falling into the 36-45 age group and 31.6% between 46-55 years. Older age groups were also represented, with 17.2% aged 56-65 years and 9.6% above 65 years. In terms of gender, 56.9% of participants were female, while 43.1% were male.Top of Form The study results found a notable gender disparity in mortality risk, with male patients demonstrating higher odds of mortality compared to females (OR = 1.25, p = 0.032). Age emerged as a significant predictor, with each additional year associated with a slight increase in mortality odds (OR = 1.02, p = 0.045). Marital status did not significantly influence mortality risk. Smoking status was identified as a significant predictor, with smokers exhibiting higher mortality risk (OR = 1.40, p = 0.005). Employment status also played a role, with self-employed individuals showing marginally lower mortality risk (OR = 0.90, p = 0.041) and unemployed individuals facing higher risk (OR = 1.50, p = 0.010) all compared to the employed. Educational level showed varying mortality risks, with high school education associated with lower risk (OR = 0.85, p = 0.030) and tertiary education linked to higher risk (OR = 1.60, p = 0.002) both compared to no formal education. CD4 cell count inversely affected mortality risk (OR = 0.99, p < 0.001). Undergoing TB screening was associated with reduced mortality odds (OR = 0.70, p = 0.003). WHO stages of HIV infection significantly influenced mortality odds, with patients in advanced stages (Stage 3: OR = 1.30, p = 0.015; Stage 4: OR = 2.00, p < 0.001) demonstrating higher odds of mortality compared to those in Stage 1.
Evaluation of Soil Micronutrients in Madagali Local Government Area of Adamawa State, Nigeria
Authors: Harrison Gideon Maghra , Stephen Kojigili T. , Hodo Gulvi Ishaya
Published: April 2024

This study was carried out to evaluate soil micronutrients in Madagali Local Government area. The importance of micronutrients in plant nutrition is high, and they should not be neglected, although they are needed in minor quantities. Twenty (20) soil samples from each selected five wards were collected which gave a total of one hundred samples used for the study. The collected soil samples were analyzed in the laboratory using appropriate methods and were subjected to descriptive statistics to ascertain their variability across the study area. Based on the laboratory outcome, iron was high with the mean values 5.11mg/kg and 4.86mg/kg for surface and sub-surface, while molybdenum was low with the mean of 0.06mg/kg and 0.04mg/kg. On the other hand, molybdenum (Mo) had the highest which was 75.6% coefficient of variation, while iron (Fe) had the lowest percentage of 30.27% coefficient of variation for surface soils. In sub-surface, manganese (Mn) had the highest percentage value which stood at 59.28% while zinc had the lowest percentage of 28.42% coefficient of variation. To achieve maximum crop production in the study area, it was recommended that addition of organic matter, liming and proper soil management practices should be adopted.
Implication of Some Energy Drink Mixture with Flunitrazepam on Endurance Pattern and Cognitive/Motor Functions in Wistar Rats
Authors: Odia K. M. , Ukoro Blessing
Published: April 2024

This study was conducted to investigate the effects of some energy drinks mixture with Flunitrazepam on endurance pattern and cognitomotor activities in male Wistar rats. 45 Wistar rats were divided into 8 groups. Group 1 received distilled water; Group 2 received energy drink (A) (3.75 mg/kg). Group 3 energy drink (A) (7.5 mg/kg) Group 4 received energy drink (B) (3.75 mg/kg). Group 5 energy drink (B) (7.5 mg/kg) Group 6 received flunitrazepam (0.03 ml/kg), Group 7 received 3.75 ml/kg of energy drink (A) and 0.03 ml/kg of flunitrazepam, and Group 8 received 3.75 ml/kg of energy drink (B) and 0.03 ml/kg of flunitrazepam. Administration of the mixture lasted for 28 days while endurance test/Cognitive and motor functions test were conducted weekly using Handgrip test, beam walk test and navigational maze test. The result reveals significant improvement in endurance pattern and cognitomotor functions in groups administered with energy drinks alone at week one, however the mixture of energy drink with various doses of Flunitrazepam showed significant impairment in both endurance pattern, and cognitomotor activities. It was therefore concluded that while the combination of energy drinks and flunitrazepam may offer short-term benefits in terms of endurance, and alertness, there is a dose and time dependent significant decline in cognitive and motor functions functions in wistar rats. The findings suggest significant variations in endurance and cognitive-motor performance across different groups, highlighting the complex interactions between stimulant and sedative substances and their implications for health and behavior.
Potential of Plant Based Metallophytes for Phytoremediation in Agriculture
Authors: Smriti . , Rai Akanksha , Shubham . , Kaushal Shilpa
Published: April 2024

Metallophytes are the unique group of plants that have evolved to thrive in metal rich environments and have drawn plenty of attention. Remediating heavy metal contaminated places with plants is an effective choice due to phytoremediation, an environmentally friendly method that uses plants to mitigate the pollution. Metallophytes are ideal options for phytoremediation applications due to their inherent traits such as hyper-accumulation, efficient metal absorption and tolerance mechanisms impacting both the plant and soil. These plants absorb and translocate heavy metals, detoxifying the soil while accumulating them in tissues. This reduces metal toxicity in soil and holds potential for resources recovery. The role of metallophytes in phytoremediation is analysed in this review with particular focus given to their ways of metal absorption, translocation and detoxification. Metallophytes have high metal tolerance and accumulation capacities due to their unique physiological and biochemical adaptations including enhanced metal sequestration in vacuoles, metal chelation by phytochelatins and activation of anti-oxidant defence systems. This review also highlights the significance of metallophytes in enhancing the soil health, reducing metal bioavailability, and promoting the ecological sustainability as well as their potential for restoring contaminated ecosystems. Utilizing the unique capabilities of metallophytes obtained from plants possesses enormous possibilities to minimise the negative effects of heavy metal pollution, protect ecosystems, and promote sustainable development for future generations. Eventually, it outlines future research approaches that aim to enhance metallophytes based phytoremediation strategies, widen their implementation and include them in holistic approaches for environmental restoration and sustainable land management.
Gaining insight into long‐term effects of inviting speculation: Does recantation help?
Authors: Compo Nadja Schreiber , Parker Janat F.
Published: July 2009

The effects of speculation on delayed recall and on source monitoring (SM) as a recantation device were examined in first and fourth graders. Two weeks after a clown show, the speculation group recalled all actions and speculated on half. The control group recalled all actions without speculating. One month and 6 months later, all children recalled all actions. Half the children were given the opportunity to recant at 1 month and all children at 6 months. Even after 6 months, speculation negatively impacted recall. Only first‐graders' script‐consistent false responses increased with time. In the speculation group, 19% of previously given script‐consistent speculations were recanted after 1 month and 20% after 6 months. Older children were better at recanting than younger children. Although recantation via SM immediately after 6‐month recall had a positive effect, SM at 1 month had no prospective effect on 6‐month recall. Copyright © 2009 John Wiley & Sons, Ltd.
Nanoscale Phase Separation and High Photovoltaic Efficiency in Solution‐Processed, Small‐Molecule Bulk Heterojunction Solar Cells
Authors: Walker Bright , Tamayo Arnold B. , Dang Xuan‐Dung , Zalar Peter , Seo Jung Hwa , Garcia Andres , Tantiwiwat Mananya , Nguyen Thuc‐Quyen
Published: July 2009

Research relating to organic solar cells based on solution‐processed, bulk heterojunction (BHJ) films has been dominated by polymeric donor materials, as they typically have better film‐forming characteristics and film morphology than their small‐molecule counterparts. Despite these morphological advantages, semiconducting polymers suffer from synthetic reproducibility and difficult purification procedures, which hinder their commercial viability. Here, a non‐polymeric, diketopyrrolopyrrole‐based donor material that can be solution processed with a fullerene acceptor to produce good quality films is reported. Thermal annealing leads to suitable phase separation and material distribution so that highly effective BHJ morphologies are obtained. The frontier orbitals of the material are well aligned with those of the fullerene acceptor, allowing efficient electron transfer and suitable open‐circuit voltages, leading to power conversion efficiencies of 4.4 ± 0.4% under AM1.5G illumination (100 mW cm−2). Small molecules can therefore be solution processed to form high‐quality BHJ films, which may be used for low‐cost, flexible organic solar cells.
Effect of styrene addition on polystyrene molecular degradation by Lewis acids
Authors: Díaz Mónica F. , Barbosa Silvia E. , Capiati Numa J.
Published: July 2009

The polystyrene molecule can suffer chain scission by beta‐cleavage mechanism in the presence of Lewis acids. This is an undesirable secondary reaction, particularly when the Friedel‐Crafts alkylation is applied to immiscible polyolefin/polystyrene (PS) blends compatibilization. It competes with the main copolymerization reaction, degrading the PS and impairing the properties of the blend. A simple experimental procedure of styrene (St) addition is proposed to compensate the PS degradation. The effect of St on the chain scission is studied by the PS molecular weight variation and reaction gases evolution. Some hypotheses are worked out to get a basic description of this complex cationic reactive process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of damp‐heat aging on the properties of ethylene‐vinyl acetate copolymer and ethylene‐ acrylic acid copolymer blends
Authors: Chen Shuangjun , Zhang Jun , Su Jun
Published: July 2009

The aim of this investigation is to evaluate the effect of damp‐heat aging on properties of ethylene‐vinyl acetate (EVA) copolymer (14 wt % vinyl acetate units), ethylene‐acrylic acid (EAA) copolymer (8 wt % acrylic acid units) and their blends. Attenuated total reflection Fourier transform infrared spectrum (ATR‐FTIR), differential scanning calorimeter (DSC), wide angle X‐ray diffraction (WAXD), and mechanical tests are employed to investigate the changes of copolymer blends' structures and properties. ATR‐FTIR tests show that increase of carbonyl index is owing to the incorporation of oxygen into the polymeric chain of EVA in the blends and has not much influence on the EAA. By DSC measurements, the low temperature endothermic peak (Tm2) of various EAA/EVA blends at about 43.7°C attributed to the secondary crystallization is increased with the aging time, which means the lamellar thickness of low temperature crystallite is increased. The increase of low temperature peaks probably derives from the interphase or even amorphous parts of both EVA and EAA components. The crystalline size detected by WAXD and degree of crystalline have both been improved by damp‐heat aging. By mechanical tests, the sample has more hardness, more modulus at 100% extension ratio, more tensile strength with less elongation at break as the proportion of EAA increase. Aging influence will induce deterioration of mechanical properties, and increase of degree of crystallinity can make the hardness, the modulus at 100% extension ratio and tensile strength increase. The two factors will both have effect on the mechanical properties of EAA/EVA blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation and characterization of poly(L‐lactide) membranes prepared by γ‐radiation‐induced grafting of N‐vinyl pyrrolidone
Authors: Chen Hao , Peng Chaorong , Yao Yongyi , Wang Jingxia , Chen Zhuping , Yang Zhirong , Xia Lijun , Liu Siyang
Published: July 2009

A copolymer, poly(L‐lactide)‐g‐poly(N‐vinyl pyrrolidone) (PLLA‐g‐PVP) was prepared with poly(L‐lactide) (PLLA) and N‐vinyl pyrrolidone in the presence of methanol as a solvent by γ‐ray irradiation. The structure of PLLA‐g‐PVP was characterized by 1H‐NMR and Fourier transform infrared spectroscopy. The PLLA‐g‐PVP graft ratio calculated by the percentage increase in weight increased with the increase of absorbed dose, and the percentage crystallinity of PLLA‐g‐PVP decreased with increasing graft ratio. The introduction of the poly(N‐vinyl pyrrolidone) chain into PLLA resulted in a decrease in the contact angle of PLLA‐g‐PVP with increasing graft ratio. In vitro degradation testing showed that PLLA‐g‐PVP had a higher degradation rate both in the weight‐loss test and molecular weight measurement because of a lower crystalline percentage and higher hydrophilicity compared to PLLA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Novel sulfonated polyimide ionomers by incorporating pyridine functional group in the polymer backbone
Authors: Lei Rui , Kang Chuanqing , Huang Yunjie , Li Yuhan , Wang Xi , Jin Rizhe , Qiu Xuepeng , Ji Xiangling , Xing Wei , Gao Lianxun
Published: July 2009

A series of sulfonated polyimides (SPIs) containing pyridine ring in the polymer backbone were synthesized by the polycondensation of 1,4,5,8‐naphthalene‐tetracarboxylic dianhydride (NTDA), 5‐(2,6‐bis(4‐aminophenyl)pyridin‐4‐yl)‐2‐methoxy benzene sulfonic acid (SDAM), and 4,4′‐diaminodiphenyl ether (ODA). Flexible, transparent, and tough membranes were obtained. Property study revealed that all the membranes displayed high thermal stability with the desulfonation and decomposition temperature higher than 290 and 540°C, respectively, as well as good mechanical property with Young's modulus larger than 1.0 GPa, maximum strength (MS) on a scale of 60–80 MPa, and elongation at break (EB) ranged from 41.79 to 75.17%. More importantly, the new materials exhibited small water uptake and excellent dimensional stability with the highest sulfonated SPI‐80 showing the maximum water uptake of 36.1%, and maximum swollen ratio of Δt = 0.038 and Δl = 0.026, respectively (Δt and Δl stands for the thickness and diameter change of the film, respectively). The high water stability exhibited by the SPI films is attributed to the formation of inner salts and/or ionic crosslinking between the sulfonic acid and pyridine functional groups, which suppresses the water uptake ability of sulfonic acid and strengthened the interpolymer chain interactions. Thus, the excellent water stability, good thermal and mechanical properties, and the technologically applicable conductivity of SPI‐80 render this material attractive for proton exchange membrane (PEM) application. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Improved dispersion of clay platelets in poly(butylene terephthalate) nanocomposite by ring‐opening polymerization of cyclic oligomers: Effect of the processing conditions and comparison with nanocomposites obtained by melt intercalation
Authors: Berti C. , Binassi E. , Colonna M. , Fiorini M. , Zuccheri T. , Karanam S. , J. Brunelle D.
Published: July 2009

Poly(butylene terephthalate) nanocomposites with organically modified montmorillonites have been prepared by in‐situ ring opening polymerization of PBT cyclic oligomers. High molecular weight polymers can be obtained by choosing the proper polymerization conditions and catalyst in very short polymerization time (10 min) and low temperature (205°C). A better dispersion of the clay and a consistently higher Mw have been obtained by this method respect to the standard melt intercalation approach, leading to improved thermo‐mechanical properties of the nanocomposite. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Thalidomide and misoprostol: Ophthalmologic manifestations and associations both expected and unexpected
Authors: Miller Marilyn T. , Ventura Liana , Strömland Kerstin
Published: July 2009

Thalidomide is a very potent teratogen capable of causing severe systemic malformations if the fetus is exposed during the sensitive period. Although structural anomalies of the eye can occur from thalidomide exposure, the most frequent eye complication is secondary to damage to the cranial nuclei in the brain stem, resulting in aberrant neurologic connections causing a condition of abnormal ocular movement, Duane syndrome. A less frequent anomalous neurologic complication is tearing when eating (paradoxical gustolacrimal tearing or “crocodile tears”) or lack of emotional tearing. The involvement of the 6th and 7th cranial nerves, often seen together in the thalidomide‐affected individual, is also characteristic of Möbius syndrome/sequence. This syndrome usually occurs sporadically, but characteristic findings of this condition have also been observed in South American children who were born after an unsuccessful attempt to induce abortion with the prostaglandin drug misoprostol (Cytotec©). Aberrant tearing also occurs in some individuals with Möbius syndrome. Autism spectrum disorder (ASD), an unexpected associated finding in a Swedish thalidomide study, is now also noted in Möbius studies, in patients both with and without exposure to misoprostol. Birth Defects Research (Part A) 2009. © 2009 Wiley‐Liss, Inc.
Inducible 70 kDa heat shock proteins protect embryos from teratogen‐induced exencephaly: Analysis using Hspa1a/a1b knockout mice
Authors: Barrier Marianne , Dix David J. , Mirkes Philip E.
Published: July 2009

BACKGROUND:

It is well known that a variety of teratogens induce neural tube defects in animals; however, less is known about proteins that play a role in protecting embryos from teratogen‐induced neural tube defects. Previously, our laboratory has shown that embryos overexpressing the 70‐Da heat shock proteins (HSPs) Hspa1a and Hspa1b were partially protected from the deleterious effects of exposure to hyperthermia in vitro.

METHODS:

In the present studies, we have used a transgenic mouse in which both of the stress‐inducible HSPs Hspa1a and Hspa1b were deleted by homologous recombination. Time‐mated Hspa1a/a1b‐/‐ (KO) and wildtype (WT) mice were exposed to hyperthermia in vivo on gestational day 8.5.

RESULTS:

Results show that 52% of the gestational day 15 fetuses from KO litters were exencephalic, whereas only 20% of WT fetuses were affected. In addition, 6% of treated KO fetuses also exhibited eye defects (microphthalmia and anopthalmia), defects not observed in WT fetuses exposed to hyperthermia. Lysotracker red staining and caspase‐3 enzyme activity were examined within 10 hours after exposure to hyperthermia, and significantly greater levels of apoptosis and enzyme activity were observed in the KO embryos compared with WT embryos.

CONCLUSIONS:

These results show that embryos lacking the Hspa1a and Hspa1b genes are significantly more sensitive to hyperthermia‐induced neural tube and eye defects, and this increased sensitivity is correlated with increased amounts of apoptosis. Thus, these results also suggest that Hspa1a and Hspa1b play an important role in protecting embryos from hyperthermia‐induced congenital defects, possibly by reducing hyperthermia‐induced apoptosis. Birth Defects Research (Part A) 2009. © 2009 Wiley‐Liss, Inc.
Neuromuscular synapse
Authors: Goodsell David S.
Published: July 2009

Diverse biological data may be used to create illustrations of molecules in their cellular context. I describe the scientific results that support a recent textbook illustration of the neuromuscular synapse. The image magnifies a portion of the synapse at one million times, showing the location and the form of individual macromolecules. Results from biochemistry, electron microscopy, and X‐ray crystallography were used to create the image.
Making ordered DNA and protein structures from computer‐printed transparency film cut‐outs
Authors: Jittivadhna Karnyupha , Ruenwongsa Pintip , Panijpan Bhinyo
Published: July 2009

Instructions are given for building physical scale models of ordered structures of B‐form DNA, protein α‐helix, and parallel and antiparallel protein β‐pleated sheets made from colored computer printouts designed for transparency film sheets. Cut‐outs from these sheets are easily assembled. Conventional color coding for atoms are used for both types of biopolymers. Arrows facilitate following chain direction for the polypeptides. For DNA, the 5′ to 3′ direction is guided by a 5′ phosphate group and a free hydroxyl group. Important chiral centers, for example, α‐carbon, deoxyribose C1′, are easily made. The main advantages of this version of DNA are the proportional major and minor grooves as in the actual molecule. More importantly, because of transparency of the film one can see successive base‐pair stacking very clearly and also the sense of relative base‐pair rotation. Because of the introduction of two central metal wire axes, the model of B‐form DNA can be twisted to give a rather good representation of A‐form and even a semblance of a left‐handed helix. The models of secondary structure of protein allow a better insight into the axial alignment of side chains, the formation of hydrogen bond, the handedness of the α‐helix, and the backbone connection between the β‐strands. Students taught by these models understand 3D features of the biopolymers better than from textbook illustrations, computer graphic representations, and even common paper and plastic versions.
Analysis of a p53 mutation associated with cancer susceptibility for biochemistry and genetic laboratory courses
Authors: Soto‐Cruz Isabel , Legorreta‐Herrera Martha
Published: July 2009

We have devised and implemented a module for an upper division undergraduate laboratory based on the amplification and analysis of a p53 polymorphism associated with cancer susceptibility. First, students collected a drop of peripheral blood cells using a sterile sting and then used FTA cards to extract the genomic DNA. The p53 region is then PCR amplified, and the PCR products are digested with the BstUI enzyme to detect the 72 codon polymorphism. Polyacrylamide gel electrophoresis is used to resolve the PCR products, and the results are statistically analyzed in the context of human population genetics. Blood samples in FTA cards were also collected from 50 women to detect the mutation in a wide range of ages and assess its relationship to familial cancer susceptibility. This module enables students to use materials and methods that are routinely used by scientific researchers to analyze polymorphisms. Therefore, it can be used for laboratory exercises in traditional biochemistry curricula as well as in the growing field of genomic science and education.
Application of polyethyleneimine‐modified scaffolds to the regeneration of cartilaginous tissue
Authors: Kuo Yung‐Chih , Ku I‐Nan
Published: July 2009

In this study, we analyzed the physicochemical and biophysical properties of three‐dimensional scaffolds modified using polyethyleneimine (PEI) and applied these scaffolds to the cultivation of bovine knee chondrocytes (BKCs). PEI was crosslinked in the bulk or on the surface of the ternary scaffolds comprising polyethylene oxide, chitin and chitosan. The results revealed that when the concentration of PEI was less than 300 μg/mL, the cytotoxicity of a scaffold was on the same order in the two method of modification. An increase in the concentration of PEI favored the adhesion of BKCs. When the amount of PEI in scaffolds is fixed, the surface‐modified scaffolds exhibited a higher adhesion efficiency of BKCs than the bulk‐modified scaffolds. For the regeneration of cartilaginous components, a higher amount of PEI in a scaffold yielded larger amounts of proliferated BKCs, secreted glycosaminoglycans, and produced collagen. In addition, the formation of neocartilage in the surface‐modified scaffolds was more effective than that in the bulk‐modified scaffolds. These tissue‐engineered scaffolds, modified by an appropriate concentration of PEI, can be potentially applied to cartilage repair in clinical trials. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Soyprotein fibers with high strength and water stability for potential medical applications
Authors: Reddy Narendra , Yang Yiqi
Published: July 2009

Fibers with mechanical properties and water stability suitable for tissue engineering have been developed from soyproteins. Proteins are biocompatible and biodegradable and are preferred over synthetic polymers for medical applications. Although plant proteins are abundant and inexpensive and can be made into various types of scaffolds, very few attempts have been made to understand the suitability of using plant proteins for medical applications, especially as fibrous substrates for tissue engineering. So far, it has not been able to obtain good quality soyprotein fibers without using toxic crosslinking agents or blending soyprotein with synthetic polymers. In this research, we have developed 100% soyprotein fibers with good strength and water stability without using any external crosslinking agents. The soyprotein fibers have better wet strength than collagen fibers and are conducive to the attachment, growth, and proliferation of mouse fibroblasts. Fibers are better substrates than films for growth and orientation of cells and are therefore preferable for tissue engineering applications. Soyprotein fibers show good potential to be novel biomaterials with properties suitable for tissue engineering and other medical applications. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009