bluuebunny/crossref_metadata_2025 huggingface dataset:
Transforming Growth Factor β Production Is Inversely Correlated with Severity of Murine Malaria Infection
Authors: Omer Fakhereldin M. , Riley Eleanor M.
Published: July 2002

We have examined the role of the immunomodulatory cytokine transforming growth factor (TGF)-β in the resolution and pathology of malaria in BALB/c mice. Circulating levels of TGF-β, and production of bioactive TGF-β by splenocytes, were found to be low in lethal infections with Plasmodium berghei. In contrast, resolving infections with P. chabaudi chabaudi or P. yoelii were accompanied by significant TGF-β production. A causal association between the failure to produce TGF-β and the severity of malaria infection was demonstrated by treatment of infected mice with neutralizing antibody to TGF-β, which exacerbated the virulence of P. berghei and transformed a resolving P. chabaudi chabaudi infection into a lethal infection, but had little effect on the course of P. yoelii infection. Parasitemia increased more rapidly in anti–TGF-β–treated mice but this did not seem to be the explanation for the increased pathology of infection as peak parasitemias were unchanged. Treatment of P. berghei–infected mice with recombinant TGF-β (rTGF-β) slowed the rate of parasite proliferation and prolonged their survival from 15 to up to 35 d. rTGF-β treatment was accompanied by a significant decrease in serum tumor necrosis factor α and an increase in interleukin 10. Finally, we present evidence that differences in TGF-β responses in different malaria infections are due to intrinsic differences between species of malaria parasites in their ability to induce production of TGF-β. Thus, TGF-β seems to induce protective immune responses, leading to slower parasite growth, early in infection, and, subsequently, appears to downregulate pathogenic responses late in infection. This duality of effect makes TGF-β a prime candidate for a major immunomodulatory cytokine associated with successful control of malaria infection.
HIV-1 Variation Diminishes CD4 T Lymphocyte Recognition
Authors: Harcourt Gillian C. , Garrard Sarah , Davenport Miles P. , Edwards Anne , Phillips Rodney E.
Published: July 2002

Effective long-term antiviral immunity requires specific cytotoxic T lymphocytes and CD4+ T lymphocyte help. Failure of these helper responses can be a principle cause of viral persistence. We sought evidence that variation in HIV-1 CD4+ T helper epitopes might contribute to this phenomenon. To determine this, we assayed fresh peripheral blood mononuclear cells from 43 asymptomatic HIV-1+ patients for proliferative responses to HIV-1 antigens. 12 (28%) showed a positive response, and we went on to map dominant epitopes in two individuals, to p24 Gag restricted by human histocompatibility leukocyte antigen (HLA)-DR1 and to p17 Gag restricted by HLA-DRB52c. Nine naturally occurring variants of the p24 Gag epitope were found in the proviral DNA of the individual in whom this response was detected. All variants bound to HLA-DR1, but three of these peptides failed to stimulate a CD4+ T lymphocyte line which recognized the index sequence. Antigenic variation was also detected in the p17 Gag epitope; a dominant viral variant present in the patient was well recognized by a specific CD4+ T lymphocyte line, whereas several natural mutants were not. Importantly, variants detected at both epitopes also failed to stimulate fresh uncultured cells while index peptide stimulated successfully. These results demonstrate that variant antigens arise in HIV-1+ patients which fail to stimulate the T cell antigen receptor of HLA class II–restricted lymphocytes, although the peptide epitopes are capable of being presented on the cell surface. In HIV-1 infection, naturally occurring HLA class II–restricted altered peptide ligands that fail to stimulate the circulating T lymphocyte repertoire may curtail helper responses at sites where variant viruses predominate.
Transforming Growth Factor β1 Inhibits Fas Ligand Expression and Subsequent Activation-induced Cell Death in T Cells via Downregulation of c-Myc
Authors: Genestier Laurent , Kasibhatla Shailaja , Brunner Thomas , Green Douglas R.
Published: July 2002

Activation-induced cell death (AICD) is a process that regulates the size and the duration of the primary immune T cell response. In this report, we investigated the mechanisms involved in the regulation of AICD by transforming growth factor β1 (TGF-β1). We found that TGF-β1 decreased apoptosis of human T cells or T cell hybridomas after activation by anti-CD3. This decrease was associated with inhibition of Fas (Apo-1/CD95) ligand (FasL) expression, whereas Fas signaling was not affected by TGF-β1. In parallel, TGF-β1 inhibited c-Myc expression in T cell hybridomas, and ectopic expression of a chimeric molecule composed of c-Myc and the steroid binding domain of the estrogen receptor (Myc-ER) blocked both the inhibition of FasL and the decrease of AICD induced by TGF-β1, providing that 4-hydroxytamoxifen was present. These results identify one mechanism by which TGF-β1 blocks AICD to allow the clonal expansion of effector T cells and the generation of memory T cells during immune responses.
Two Waves of Nuclear Factor κb Recruitment to Target Promoters
Authors: Saccani Simona , Pantano Serafino , Natoli Gioacchino
Published: July 2002

Proinflammatory stimuli induce the rapid and transient translocation of nuclear factor (NF)-κB to the nucleus, where it activates transcription from several genes, including those encoding inflammatory cytokines and chemokines, adhesion molecules, and cytoprotective proteins. Using chromatin immunoprecipitation, we show that after an acute stimulation two distinct waves of NF-κB recruitment to target promoters occur: a fast recruitment to constitutively and immediately accessible (CIA) promoters and a late recruitment to promoters requiring stimulus-dependent modifications in chromatin structure to make NF-κB sites accessible (promoters with regulated and late accessibility [RLA]). Our results suggest that a mechanism of specificity in NF-κB–dependent transcriptional responses relies on the ability of individual stimuli to make RLA promoters accessible to NF-κB before its rapid extrusion from the nucleus.
Crystal structure of the GABAA‐receptor‐associated protein, GABARAP
Authors: Bavro Vassiliy N , Sola Maria , Bracher Andreas , Kneussel Matthias , Betz Heinrich , Weissenhorn Winfried
Published: July 2002

The GABAA‐receptor‐associated protein (GABARAP) is a member of a growing family of intracellular membrane trafficking and/or fusion proteins and has been implicated in plasma membrane targeting and/or recycling of GABAA receptors. GABARAP is localized on intracellular membranes such as the trans‐Golgi network, binds to the γ 2 subunit of GABAA receptors and interacts with microtubules and the N‐ethylmaleimide‐sensitive factor. We report the X‐ray crystal structure of mammalian GABARAP at 2.0 Å resolution. GABARAP consists of an N‐terminal basic helical region, which has been implicated in tubulin binding, and a core structure with a conserved ubiquitin‐like fold. Consistent with the high extent of sequence conservation among GABARAP homologues from plants to mammals, one face of the core structure is absolutely conserved while the opposite face shows considerable divergence. These features are in agreement with the conserved surface mediating protein–protein interactions shared by all members of the family, whereas the non‐conserved surface region may play specific roles, such as docking to particular membrane receptors.
In-vitro bacteriostatic activity of levofloxacin and three other fluoroquinolones against penicillin-susceptible and penicillin-resistant Streptococcus pneumoniae
Authors: Frémaux A. , Sissia G. , Geslin P.
Published: July 2002

The purpose of this study was to investigate the in-vitrobacteriostatic activity of levofloxacin in comparison with that of ofloxacin, sparfloxacin and ciprofloxacin against 205 strains of Streptococcus pneumoniae (101 penicillin-susceptible, 51 penicillin-intermediate and 53 penicillin-resistant). The isolates were provided between September 1996 and October 1996 by French hospitals participating in the National Co-operative Survey of Pneumococcal Infections. The determination of MICs (mg/L) was made by the agar dilution method. The MIC 50 and MIC 90 values of the four fluoroquinolones for the three classes of S. pneumoniae (penicillin-susceptible, penicillin-intermediate and penicillin-resistant) were not significantly different. In contrast, the differences in in-vitro activity observed among the four fluoroquinolones against the 205 strains allowed them to be separated into three groups: sparfloxacin (MIC 50/90 0.25 mg/L); ciprofloxacin and levofloxacin (MIC 50 0.5 and 1 mg/L respectively, MIC 90 1 mg/L); and ofloxacin (MIC 50 1 mg/L, MIC 90 2 mg/L). A total of 204 of the strains had a levofloxacin MIC between 0.25 mg/L and 1 mg/L, and only one of the 205 strains was highly resistant (MIC 16 mg/L). Whatever the level of susceptibility to penicillin, the relative bacteriostatic activity was, in descending order of activity, sparfloxacin, levofloxacin/ciprofloxacin and ofloxacin. These results suggest levofloxacin has potential for the treatment of pneumococcal infections.
Resistance to insecticides in Heliothine Lepidoptera: a global view
Authors: McCaffery A. R.
Published: July 2002

The status of resistance to organophosphate, carbamate, cyclodiene and pyrethroid insecticides in the heliothine Lepidoptera is reviewed. In particular, resistance in the tobacco budworm,
Heliothis virescens
, and the corn earworm,
Helicoverpa zea
, from the New World, and the cotton bollworm,
Helicoverpa armigera
, from the Old World, are considered in detail. Particular emphasis has been placed on resistance to the most widely used of these insecticide groups, the pyrethroids. In each case, the incidence and current status of resistance are considered before a detailed view of the mechanisms of resistance is given. Controversial issues regarding the nature of mechanisms of resistance to pyrethroid insecticides are discussed. The implications for resistance management are considered.
Extracellular glutamate diffusion determines the occupancy of glutamate receptors at CA1 synapses in the hippocampus
Authors: Kullmann Dimitri M. , Min Ming-Yuan , Asztely Fredrik , Rusakov Dmitri A.
Published: July 2002

Following exocytosis at excitatory synapses in the brain, glutamate binds to several subtypes of postsynaptic receptors. The degree of occupancy of AMPA and NMDA receptors at hippocampal synapses is, however, not known. One approach to estimate receptor occupancy is to examine quantal amplitude fluctuations of postsynaptic signals in hippocampal neurons studied
in vitro
. The results of such experiments suggest that NMDA receptors at CA1 synapses are activated not only by glutamate released from the immediately apposed presynaptic terminals, but also by glutamate spillover from neighbouring terminals. Numerical simulations point to the extracellular diffusion coefficient as a critical parameter that determines the extent of activation of receptors positioned at different distances from the release site. We have shown that raising the viscosity of the extracellular medium can modulate the diffusion coefficient, providing an experimental tool to investigate the role of diffusion in activation of synaptic and extrasynaptic receptors. Whether intersynaptic cross–talk mediated by NMDA receptors occurs
in vivo
remains to be determined. The theoretical and experimental approaches described here also promise to shed light on the roles of metabotropic and kainate receptors, which often occur in an extrasynaptic distribution, and are therefore positioned to sense glutamate escaping from the synaptic cleft.
Scopolamine Enhances Generalization between Odor Representations in Rat Olfactory Cortex
Authors: Wilson Donald A.
Published: July 2002

Acetylcholine (ACh) has a critical, modulatory role in plasticity in many sensory systems. In the rat olfactory system, both behavioral and physiological data indicate that ACh may be required for normal odor memory and synaptic plasticity. Based on these data, neural network models have hypothesized that ACh muscarinic receptors reduce interference between learned cortical representations of odors within the piriform cortex. In this study, odor receptive fields of rat anterior piriform cortex (aPCX) single-units for alkane odors were mapped before and after either a systemic injection of the muscarinic receptor antagonist scopolamine (0.5 mg/kg) or aPCX surface application of 500 μM scopolamine (or saline/ACSF controls). Cross-habituation between alkanes differing by two to four carbons was then examined following a 50-sec habituating stimulus. The results demonstrate that neither aPCX spontaneous activity nor odor-evoked activity (receptive field) was affected by scopolamine, but that cross-habituation in aPCX neurons was enhanced significantly by either systemic or cortical scopolamine. These results indicate that scopolamine selectively enhances generalization between odor representations in aPCX in a simple memory task. Given that ACh primarily affects intracortical association fibers in the aPCX, the results support a role for the association system in odor memory and discrimination and indicate an important ACh modulatory control over this basic sensory process.
Melody lead in piano performance: Expressive device or artifact?
Authors: Goebl Werner
Published: July 2002

As reported in the recent literature on piano performance, an emphasized voice (the melody) tends to be played not only louder than the other voices, but also about 30 ms earlier (melody lead). It remains unclear whether pianists deliberately apply melody lead to separate different voices, or whether it occurs because the melody is played louder (velocity artifact). The velocity artifact explanation implies that pianists initially strike the keys simultaneously; it is only different velocities that make the hammers arrive at different points in time. The measured note onsets in these studies, mostly derived from computer-monitored pianos, represent the hammer-string impact times. In the present study, the finger-key contact times are calculated and analyzed as well. If the velocity artifact hypothesis is correct, the melody lead phenomenon should disappear at the finger-key level. Chopin’s Ballade op. 38 (45 measures) and Etude op. 10/3 (21 measures) were performed on a Bösendorfer computer-monitored grand piano by 22 skilled pianists. The hammer-string asynchronies among voices closely resemble the results reported in the literature. However, the melody lead decreases almost to zero at the finger-key level, which supports the velocity artifact hypothesis. In addition to this, expected onset asynchronies are predicted from differences in hammer velocity, if finger-key asynchronies are assumed to be zero. They correlate highly with the observed melody lead.
Evidence for an across-frequency, between-channel process in asymptotic monaural temporal gap detection
Authors: Formby C. , Gerber M. J. , Sherlock L. P. , Magder L. S.
Published: July 2002

Monaurally measured temporal gap detection (TGD) thresholds characteristically increase as the frequency difference is increased over a range of about half an octave to an octave between two sinusoids that mark the onset and offset of the silent gap. For greater sinusoidal frequency separations, the TGD thresholds often become asymptotic. This pattern probably reflects two different processes. The first process likely reflects within-channel processing within a single auditory filter or channel. The second process is less certain, but may reflect between-channel processing of the silent gap stimulus across two or more independent frequency channels. To evaluate the hypothesis that asymptotic monaural gap detection can be explained by a simple between-channel process, TGD thresholds were measured as a function of frequency separation between a pregap sinusoid presented to the left ear (channel 1) and a postgap sinusoid, of higher frequency, presented to the right ear (channel 2). The rationale for dichotic presentation of the sinusoidal markers and gap signal followed from the fact that the gap detection task must be performed between two independent channels by combining the outputs from each channel (ear) and recovering the gap information centrally. The resulting TGD thresholds for pregap sinusoids from 250 to 4000 Hz were relatively invariant and increased only slightly with increasing marker frequency separation. The average TGD thresholds for four listeners were in the range of 30 to 40 ms, which corresponded closely with their asymptotic TGD thresholds for the same set of stimulus conditions measured monaurally. This correspondence of the two data sets supports an across-frequency, between-channel process for asymptotic monaural gap detection at marker frequency separations greater than about half an octave.
GPHR‐mediated acidification of the Golgi lumen is essential for cholesterol biosynthesis in the brain
Authors: Sou Yu‐shin , Yamaguchi Junji , Kameda Hiroshi , Masuda Keisuke , Maeda Yusuke , Uchiyama Yasuo , Koike Masato
Published: September 2022

The Golgi pH regulator (GPHR) is essential for maintaining the function and morphology of the Golgi apparatus through the regulation of luminal acidic pH. Abnormal morphology of the Golgi apparatus is associated with neurodegenerative diseases. Here, we found that knockout of GPHR in the mouse brain led to morphological changes in the Golgi apparatus and neurodegeneration, which included brain atrophy, neuronal cell death, and gliosis. Furthermore, in the GPHR knockout mouse brain, transcriptional activity of sterol regulatory element‐binding protein 2 (SREBP2) decreased, resulting in a reduction in cholesterol levels. GPHR‐deficient cells exhibited suppressed neurite outgrowth, which was recovered by exogenous expression of the active form of SREBP2. Our results show that GPHR‐mediated luminal acidification of the Golgi apparatus maintains proper cholesterol levels and, thereby, neuronal morphology.
Mutation of the galectin‐3 glycan‐binding domain (Lgals3‐R200S) enhances cortical bone expansion in male mice and trabecular bone mass in female mice
Authors: Maupin Kevin A. , Diegel Cassandra R. , Stevens Payton D. , Dick Daniel ,   VAI Vivarium and Transgenic Core, Williams Bart O.
Published: September 2022

We previously observed that genomic loss of galectin‐3 (Gal‐3; encoded by Lgals3) in mice has a significant protective effect on age‐related bone loss. Gal‐3 has both intracellular and extracellular functionality, and we wanted to assess whether the affect we observed in the Lgals3 knockout (KO) mice could be attributed to the ability of Gal‐3 to bind glycoproteins. Mutation of a highly conserved arginine to a serine in human Gal‐3 (LGALS3‐R186S) blocks glycan binding and secretion. We generated mice with the equivalent mutation (Lgals3‐R200S) and observed a subsequent reduction in Gal‐3 secretion from mouse embryonic fibroblasts and in circulating blood. When examining bone structure in aged mice, we noticed some similarities to the Lgals3‐KO mice and some differences. First, we observed greater bone mass in Lgals3‐R200S mutant mice, as was previously observed in Lgals3‐KO mice. Like Lgals3‐KO mice, significantly increased trabecular bone mass was only observed in female Lgals3‐R200S mice. These results suggest that the greater bone mass observed is driven by the loss of extracellular Gal‐3 functionality. However, the results from our cortical bone expansion data showed a sex‐dependent difference, with only male Lgals3‐KO mice having an increased response, contrasting with our earlier study. These notable sex differences suggest a potential role for sex hormones, most likely androgen signaling, being involved. In summary, our results suggest that targeting extracellular Gal‐3 function may be a suitable treatment for age‐related loss of bone mass.
Distributed multichannel Wiener filtering for speech enhancement in acoustic sensor networks
Authors: Chang Ruijiang , Chen Zhe , Yin Fuliang
Published: September 2022

The performance of speech processing algorithms in wireless acoustic sensor networks (WASNs) is severely degraded by diffuse noise. To address this problem, a distributed speech enhancement algorithm for WASNs is proposed in this article. The parameterized multichannel Wiener filter is first improved by exploiting all cross‐correlation information among nodes. Next, using the Hadamard element‐wise product of label matrix and cross‐correlation matrix, the distributed parameterized multichannel Wiener filter based on the in‐network summation is presented. Moreover, by making the tradeoff between communication cost and enhancement performance, a simplified distributed algorithm is proposed. Finally, the noise reduction performance of the proposed method is theoretically analyzed. The proposed method achieves good speech enhancement performance and requires only in‐network summation in WASNs. Experimental results reveal the validity of the proposed method.
High Efficiency Aqueous Solution Sprayed CIGSSe Solar Cells: Effects of Zr4+‐Alloyed In2S3 Buffer and K‐Alloyed CIGSSe Absorber
Authors: Mina Md Salahuddin , Kim SeongYeon , Enkhbat Temujin , Enkhbayar Enkhjargal , Kim JunHo
Published: September 2022

Even though solution‐processed Cu(In,Ga)(S,Se)2 (CIGSSe) solar cells have been developed for long time, their power conversion efficiency (PCE) is still much behind that achieved by vacuum‐based process, and some solvents used in solution‐based processes are not environmental friendly. High‐efficiency CIGSSe solar cells made by using water‐based spray deposition in an air environment are reported. Water is the most eco‐friendly and cheapest solvent compared to the other solvents used in solution‐based fabrication. In2S3‐based buffer (eco‐friendly Cd‐free buffer) and CdS buffer are tested as a buffer layer. For higher PCE with In2S3‐based buffer, a Zr4+‐alloyed In2S3 is used and Zr4+ alloying effects are investigated. It is found that Zr4+ alloying increases the electron concentration in the buffer and passivates defect states in the CIGSSe absorber, which enhance PCE significantly. On the other hand, it is found that K‐alloying into the CIGSSe absorber passivates defects in the CIGSSe absorber, which further increases PCE. Owing to the observed beneficial effects, highest PCE of 16.08% and 17.74% is achieved with Zr4+‐In2S3 buffer and CdS buffer, respectively. In addition, since fabricated solar cells are made with bandgap below 1.15 eV, they can be utilized as a bottom cell for high efficiency tandem cell.
Understanding the Solution‐State Doping of Donor–Acceptor Polymers Through Tailored Side Chain Engineering for Thermoelectrics
Authors: Suh Eui Hyun , Jeong Moon‐Ki , Lee Kyumin , Jeong WonJo , Jeong Yong Jin , Jung In Hwan , Jang Jaeyoung
Published: September 2022

Among the molecular doping methods widely utilized to control charge carriers in organic thermoelectric (TE) devices, solution mixing is attractive for the preparation of uniform and thick TE films to obtain high output powers. However, the effects of doping behavior in solution‐state polymers on their film properties are still not well understood, particularly for donor–acceptor (D‐A) polymers, key materials for high‐performance (opto)electronic devices. Here, by preparing three D‐A polymers with engineered side chains, the aggregation effects of D‐A polymers on the doping behavior in the solution and film states are demonstrated. In a less aggregated polymer, mixing the solution with a p‐dopant leads to the Lewis complex formation, which reduces doping efficiency and power factor. However, solution mixing of aggregated polymers induces the formation of ion pairs with the dopant, resulting in power factors that are two orders of magnitude higher at 23.7 µW m−1 K−2. Doping in the film state where aggregation is induced facilitates ion‐pair formation, resulting in smaller deviation in TE properties (power factors = 9.0–16.4 µW m−1 K−2) despite differences in their ordering structures. These results provide an in‐depth understanding of efficient solution‐state doping of D‐A polymers for TEs.
A Biodegradable Metal‐Polymer Composite Stent Safe and Effective on Physiological and Serum‐Containing Biomimetic Conditions
Authors: Zhang Hongjie , Zhang Wanqian , Qiu Hong , Zhang Gui , Li Xin , Qi Haiping , Guo Jingzhen , Qian Jie , Shi Xiaoli , Gao Xian , Shi Daokun , Zhang Deyuan , Gao Runlin , Ding Jiandong
Published: September 2022

The new‐generation coronary stents are expected to be biodegradable, and then the biocompatibility along with biodegradation becomes more challenging. It is a critical issue to choose appropriate biomimetic conditions to evaluate biocompatibility. Compared with other candidates for biodegradable stents, iron‐based materials are of high mechanical strength, yet have raised more concerns about biodegradability and biocompatibility. Herein, a metal‐polymer composite strategy is applied to accelerate the degradation of iron‐based stents in vitro and in a porcine model. Furthermore, it is found that serum, the main environment of vascular stents, ensured the safety of iron corrosion through its antioxidants. This work highlights the importance of serum, particularly albumin, for an in vitro condition mimicking blood‐related physiological condition, when reactive oxygen species, inflammatory response, and neointimal hyperplasia are concerned. The resultant metal‐polymer composite stent is implanted into a patient in clinical research via interventional treatment, and the follow‐up confirms its safety, efficacy, and appropriate biodegradability.
Recent Progress on Defect Passivation of All‐Inorganic Halide Perovskite Solar Cells
Authors: Wang Boyang , Yin Xingtian , Iqbal Shoaib , Que Meidan , Que Wenxiu
Published: September 2022

All‐inorganic halide perovskite materials have attracted increasing attentions in recent years due to their superior stability and adjustable band gap which make them very suitable for the top cells of multi‐junction solar cells. Nonetheless, the power conversion efficiency of all‐inorganic halide perovskite solar cells is still far from satisfaction. The widespread use of the conventional solution method in the preparation process causes many different defects and carrier transport barriers at the grain boundaries and interfaces of the perovskite films, which can cause severe hysteresis behavior and non‐radiative recombination, resulting in low efficiency and hindering their rapid commercialization. While, the selection of suitable passivation materials and techniques can have the most significant potential in reducing the defect recombination centers between the bulk perovskite, the film surface and grain boundaries, and the interface between the various communities (perovskite/electron transport layer [ETL], perovskite/hole transport layer [HTL]). Herein, this study reviews the current research process on various passivation strategies developed for all‐inorganic halide perovskite solar cells, especially for the defects in the perovskite surface, and grain boundaries, perovskite/HTL interface and perovskite/ETL interface. Finally, the authors look ahead to the prospects and challenges of exploring defect passivation in all‐inorganic halide perovskite solar cells.
Recent Advances in Silver nanozymes: Concept, Mechanism, and Applications in Detection
Authors: Mishra Sanya , Abdal‐hay Abdalla , Rather Sami ullah , Tripathi Ravi Mani , Shekh Faheem A.
Published: September 2022

Natural enzymes accelerate substrate‐specific reactions making them of exquisite interest for various applications. However, their appeal is lost in a practical setting due to low stability and high preparation expenses. This is the primary reason behind the flourishing in the research of nanozyme, i.e., artificial enzymes, in the past decade. Their unique physicochemical properties make them a promising candidate for various applications, especially in diagnostics and detection. They possess an enzyme‐like activity and can overcome the drawbacks of natural protein‐based enzymes. Nanozymes are nanomaterials that show enzyme‐like catalytic activity and have great potential to replace natural enzymes for industrial applications. The scope of tuning these nanozymes enhances their catalytic activity and provides specificity, benefiting disease diagnosis and drug delivery. This review aims to report the applications of silver nanozymes in disease diagnosis, glucose detection, and cancer therapy. Their role in detecting heavy metal ions for environmental safety has also been highlighted.
Assembly, Properties, and Application of Ordered Group II–VI and IV–VI Colloidal Semiconductor Nanoparticle Films
Authors: Micheel Mathias , Baruah Raktim , Kumar Krishan , Wächtler Maria
Published: September 2022

Colloidal semiconductor nanocrystals, in particular cadmium and lead chalcogenide particles, are pivotal materials in many optoelectronic applications. While synthetic advances in the past decades now allow precise control of their size, shape, and composition, they must be processed from dispersion into functional films for many applications, which presents additional challenges. In this review, recent progresses in the field of nanoparticle self‐assembly into functional thin films with precise control over nanoparticle order and orientation are discussed. A comprehensive overview on characterization methods used in the study of such ordered materials is provided and the gas–liquid interfacial self‐assembly and electric field driven deposition as the two most promising ways to generate superstructures with defined thickness, order, and orientation are discussed. The superstructure–property relationships are then reviewed with emphasis on charge migration through the film and radiative processes. Last, challenges and open questions in the field are addressed.
Area‐Selective Atomic Layer Deposition on Functionalized Graphene Prepared by Reversible Laser Oxidation
Authors: Mentel Kamila K. , Emelianov Aleksei V. , Philip Anish , Johansson Andreas , Karppinen Maarit , Pettersson Mika
Published: September 2022

Area‐selective atomic layer deposition (ALD) is a promising “bottom‐up” alternative to current nanopatterning techniques. While it has been successfully implemented in traditional microelectronic processes, selective nucleation of ALD on 2D materials has so far remained an unsolved challenge. In this article, a precise control of the selective deposition of ZnO on graphene at low temperatures (<250 °C) is demonstrated. Maskless femtosecond laser writing is used to locally activate predefined surface areas (down to 300 nm) by functionalizing graphene to achieve excellent ALD selectivity (up to 100%) in these regions for 6‐nm‐thick ZnO films. The intrinsic conductive properties of graphene can be restored by thermal annealing at low temperature (300 °C) without destroying the deposited ZnO patterns. As the graphene layer can be transferred onto other material surfaces, the present patterning technique opens new attractive ways for various applications in which the functionalized graphene is utilized as a template layer for selective deposition of desired materials.
Elemental Doping and Interface Effects on Spin–Orbit Torques in CoSi‐Based Topological Semimetal Thin Films
Authors: Tang Ke , Wen Zhenchao , Seki Takeshi , Sukegawa Hiroaki , Mitani Seiji
Published: September 2022

This work reports on Ni and Fe doping and interface effects on spin–orbit torques (SOTs) generated from a topological semimetal CoSi. CoSi thin films grown on Al2O3(0001) substrates by magnetron co‐sputtering show the B20 structure with a texture in the [210] orientation even after Ni or Fe doping. The SOTs from the films exerted on the magnetization of a CoFeB layer are evaluated by harmonic Hall and spin‐torque ferromagnetic resonance measurements. The spin Hall efficiency ξSH of the textured B20‐CoSi at room temperature is determined to be 9.6%, which decreases to 1.8% for Ni0.15Co0.85Si and to 5.5% for Fe0.26Co0.74Si. The electrical conductivity dependence of the spin Hall conductivity is assigned to the regime of intrinsic mechanism of spin Hall effect, suggesting that the reduction of ξSH with the element doping can be due to the degradation in topological electronic structures of CoSi. Furthermore, inserting a Cu layer at the Co(Ni, Fe)Si/CoFeB interface results in an increase of the ξSH up to 10.9% for CoSi, 4.0% for Ni0.15Co0.85Si, and 8.3% for Fe0.26Co0.74Si. These enhancements of the ξSH can be attributed to the improvement in the interfacial spin transparency between the Co(Ni, Fe)Si and CoFeB layers.
Enhancing Horizontal Ratio of Transition Dipole Moment in Homoleptic Ir Complexes for High Outcoupling Efficiency of Organic Light‐Emitting Diodes
Authors: Kim Jae‐Min , Hwang Kyu Young , Kim Sungmin , Lim Junseop , Kang Byungjoon , Lee Kum Hee , Choi Byoungki , Kwak Seung‐Yeon , Lee Jun Yeob
Published: September 2022

The light‐emitting dipole orientation (EDO) of a phosphorescent emitter is a key to improving the external quantum efficiency (EQE) of organic light‐emitting diodes (OLEDs) without structural modification of the device. Here, four homoleptic Ir complexes as a phosphorescent emitter are systematically designed based on the molecular structure of tris(2‐phenylpyridine)iridium(III) (Ir(ppy)3) to control the EDO. Trimethylsilane, methyl, 2‐methylpropyl, and cyclopentylmethyl group substituted to pyridine ring of the ligand contribute to the improvement of the EDO from 76.5% for Ir(ppy)3 to 87.5%. A linear relationship between the EDO and the aspect ratio (geometric anisotropy factor) is founded, implying the importance of the effective area for the nonbonding force between host and dopant molecules. Also, it is investigated that the EDO enhancement mainly originates from the vertical alignment of the C3 axis of molecule in the substrate axis rather than the change in the direction of the transition dipole alignment in the molecular axis. The optical simulation reveals that the outcoupling efficiency of phosphorescent OLEDs adopting new dopants reaches 38.4%. The green OLEDs exhibiting 28.3% of EQE, 103.2 cd A–1 of current efficiency, and 98.2 lm W–1 of power efficiency are demonstrated, which is understood to have little electrical loss.
Development of Air‐Stable Photomultiplication‐Type Organic Photodetector and Analysis of Active Layer using Removable Top Electrode
Authors: Shimanoe Shuhei , Fukuda Kenjiro , Someya Takao , Yokota Tomoyuki
Published: September 2022

Organic photodetectors (OPDs) are preferred for use in biological sensing applications owing to their mechanical flexibility and good optical characteristics. To enhance the sensitivity of OPDs, a photomultiplication‐type OPD (PMOPD), which can produce amplification at two terminals, has been developed. However, the stability of this photodetector is an issue when it is used in image sensors or other applications. In this study, an air‐stable PMOPD with a PBDTTT‐OFT:PC61BM active layer that has high responsivity in the near‐infrared region is developed. Furthermore, an OPD with a removable top electrode has been developed. Using this new device structure, the authors can directly and continuously evaluate the active layer of the device after using it in the air. It has been observed that the device does not exhibit any chemical changes in the active layer.
Kinetic modeling of oxidative dehydrogenation of propane with CO2 over MoOx/La2O3–Al2O3 in a fluidized bed
Authors: Balogun Majid L. , Gambo Yahya , Adamu Sagir , Ba‐Shammakh Mohammed S. , Hossain Mohammad M.
Published: September 2022

A 4‐step kinetic model of CO2‐assisted oxidative dehydrogenation (ODH) of propane to C2/C3 olefins over a novel MoOx/La2O3–γAl2O3 catalyst was developed. Kinetic experiments were conducted in a CREC Riser Simulator at various reaction temperatures (525–600 °C) and times (15–30 s). The catalyst was highly selective towards propylene at all combinations of the reaction conditions. Langmuir‐Hinshelwood type kinetics were formulated considering propane ODH, uni‐ and bimolecular cracking of propane to produce a C1‐C2 species. It was found that the one site type model adequately fitted the experimental data. The activation energy for the formation of propylene (67.8 kJ/mol) is much lower than that of bimolecular conversion of propane to ethane and ethylene (303 kJ/mol) as well as the direct cracking of propane to methane and ethylene (106.7 kJ/mol). The kinetic modeling revealed the positive effects of CO2 towards enhancing the propylene selectivity over the catalyst.
Anticancer Approach Inspired by the Hepatotoxic Mechanism of Pyrrolizidine Alkaloids with Glycosylated Artificial Metalloenzymes
Authors: Kurimoto Michitaka , Chang Tsung‐che , Nishiyama Yoshitake , Suzuki Takehiro , Dohmae Naoshi , Tanaka Katsunori , Yokoshima Satoshi
Published: September 2022

Metabolic oxidation of pyrrolizidine alkaloids (PAs) from herbal and dietary supplements by cytochrome P450 produces dehydro‐PAs (DHPs), which leads to toxicities. A highly reactive cation species generated from the active pyrrole ring of DHPs readily reacts with various cellular components, causing hepatotoxicity and cytotoxicity. Inspired by PA‐induced hepatic damage, we developed a therapeutic approach based on a cyclization precursor that can be transformed into a synthetic DHP under physiological conditions through gold‐catalyzed 5‐endo‐dig cyclization using a gold‐based artificial metalloenzyme (ArM) instead of through metabolic oxidation by cytochrome P450. In cell‐based assays, the synthesis of the DHP by a cancer‐targeting glycosylated gold‐based ArM substantially suppressed cell growth of the targeted cancer cells without causing cytotoxicity to untargeted cells, highlighting the potential of the strategy to be used therapeutically in vivo.
High‐Capacity Splitting of Mono‐ and Dibranched Hexane Isomers by a Robust Zinc‐Based Metal–Organic Framework
Authors: Yu Liang , Ullah Saif , Wang Hao , Xia Qibin , Thonhauser Timo , Li Jing
Published: September 2022

High‐efficiency separation of C6 alkanes, particularly the mono‐ and dibranched isomers by using porous solids, is of paramount significance in the petrochemical industry and, remains a daunting challenge. In this work, we report the complete separation of linear/monobranched hexanes from their dibranched isomers through selective size‐exclusion by a microporous MOF, Zn‐tcpt (H3tcpt=2,4,6‐tris(4‐carboxyphenoxy)‐1,3,5‐triazine), with a two‐fold interpenetrated structure of hms nets. Importantly, its adsorption capacity and selectivity are notably higher than those of the previously reported adsorbents that can split mono‐ and dibranched alkane isomers. Dynamic breakthrough measurements verify the excellent separation of C6 alkane isomers by Zn‐tcpt, and the size‐exclusion based separation mechanism has been confirmed by ab initio materials modeling. The high‐efficiency separation of alkane isomers by Zn‐tcpt can be attributed to its optimal pore dimensions as well as high porosity.
Silver‐Free C−H Activation: Strategic Approaches towards Realizing the Full Potential of C−H Activation in Sustainable Organic Synthesis
Authors: Mondal Arup , van Gemmeren Manuel
Published: September 2022

The activation of carbon−hydrogen bonds is considered as one of the most attractive techniques in synthetic organic chemistry because it bears the potential to shorten synthetic routes as well as to produce complementary product scopes compared to traditional synthetic strategies. However, many current methods employ silver salts as additives, leading to stoichiometric metal waste and thereby preventing the full potential of C−H activation to be exploited. Therefore, the development of silver‐free protocols has recently received increasing attention. Mechanistically, silver can serve various roles in C−H activation and thus, avoiding the use of silver requires different approaches based on the role it serves in a given process. In this Review, we present the comparison of silver‐based and silver‐free methods. Focusing on the strategic approaches to develop silver‐free C−H activation, we provide the reader with the means to develop sustainable methods for C−H activation.
In Vivo Olefin Metathesis in Microalgae Upgrades Lipids to Building Blocks for Polymers and Chemicals
Authors: Schunck Natalie S. , Mecking Stefan
Published: September 2022

Sustainable sources are key to future chemicals production. Microalgae are promising resources as they fixate carbon dioxide to organic molecules by photosynthesis. Thereby they produce unsaturated fatty acids as established raw materials for the industrial production of chemical building blocks. Although these renewable feedstocks are generated inside cells, their catalytic upgrading to useful products requires in vitro transformations. A synthetic catalysis inside photoautotrophic cells has remained elusive. Here we show that a catalytic conversion of renewable substrates can be realized directly inside living microalgae. Organometallic catalysts remain active inside the cells, enabling in vivo catalytic olefin metathesis as new‐to‐nature transformation. Stored lipids are converted to long‐chain dicarboxylates as valuable building blocks for polymers. This is a key step towards the long‐term goal of producing desired renewable chemicals in microalgae as living “cellular factories”.
Isoxazole Nucleosides as Building Blocks for a Plausible Proto‐RNA
Authors: Xu Felix , Crisp Antony , Schinkel Thea , Dubini Romeo C. A. , Hübner Sarah , Becker Sidney , Schelter Florian , Rovó Petra , Carell Thomas
Published: September 2022

The question of how RNA, as the principal carrier of genetic information evolved is fundamentally important for our understanding of the origin of life. The RNA molecule is far too complex to have formed in one evolutionary step, suggesting that ancestral proto‐RNAs (first ancestor of RNA) may have existed, which evolved over time into the RNA of today. Here we show that isoxazole nucleosides, which are quickly formed from hydroxylamine, cyanoacetylene, urea and ribose, are plausible precursors for RNA. The isoxazole nucleoside can rearrange within an RNA‐strand to give cytidine, which leads to an increase of pairing stability. If the proto‐RNA contains a canonical seed‐nucleoside with defined stereochemistry, the seed‐nucleoside can control the configuration of the anomeric center that forms during the in‐RNA transformation. The results demonstrate that RNA could have emerged from evolutionarily primitive precursor isoxazole ribosides after strand formation.
Selective oxidation of C (sp3)—H bonds enabled by ruthenium clusters containing pyridine‐alkoxide ligands
Authors: Hao Zhiqiang , Yue Xiaohui , Zhou Xiaoyu , Ma Zhihong , Han Zhangang , Lin Jin , Lu Guo‐Liang
Published: September 2022

Reactions of Ru3(CO)12 with 6‐methyl‐2‐pyridinyl‐ethanol ligands 6‐CH3‐2‐PyCH2CR1R2OH [R1H, R22‐CH3OC6H4 (L1H); R1H, R22‐CF3C6H4 (L2H); R1R2CH3 (L3H); and R1H, R22,6‐(CH3O)2C6H3 (L4H)] in refluxing THF afforded the corresponding trinuclear ruthenium clusters (6‐CH3‐2‐PyCH2CR1R2O)(μ2‐H)Ru3(CO)9 [R1H, R22‐CH3OC6H4 (1); R1H, R22‐CF3C6H4 (2); R1R2CH3 (3); and R1H, R22,6‐(CH3O)2C6H3 (4)], respectively. All the four new clusters were well characterized by elemental analysis, IR, 1H, and 13C nuclear magnetic resonance. Furthermore, their crystal structures were determined by single‐crystal X‐ray diffraction analysis. The ruthenium clusters were proved to be efficient catalysts for the oxidation of saturated CH bonds with tert‐butyl hydroperoxide (TBHP) as the oxidant in CH3CN/H2O (1:4) at room temperature.
Development and performance evaluation of cool black surface on thermoplastic polyolefins via incorporation of non‐near infrared absorptive pigments
Authors: Girişken Çağla , Seven Senem Avaz , Ersoy Osman Gökhan , Menceloğlu Yusuf Ziya
Published: September 2022

Absorption of the near‐infrared (NIR) region of solar irradiance spectrum of the sunlight causes increase of the temperature of black inner parts of vehicles. The surface temperature of these parts can be decreased by reflecting or transmitting the NIR region of sunlight. This study intends to decrease the temperature of black surfaces that are exposed to sunlight and create cool black surfaces by preventing the absorption of the NIR region of the solar irradiance spectrum. Incorporation of cool black pigments having NIR reflective or NIR transparent properties into thermoplastic olefins (TPOs) was studied. A series of compounds were generated containing only NIR reflective pigment (REF), only NIR transparent pigment (TRANS) and the mixture of these two pigments in specific loading levels. The surface temperature of black TPO compounds were compared to the TPO compounds containing conventional pigments. Results showed that an optimum TPO compound having cool black surface was obtained with the sample MIX‐5 (2% REF + 0.4% TRANS) which demonstrated 28.2% cooling compared to samples with carbon black, 9.04 MPa tensile strength, 1200% elongation at break and mold shrinkage values of 0.61% and 0.11% at directions parallel and perpendicular to flow respectively.
Jaw mechanics in macrophagous lamniform sharks and their evolutionary and functional implications
Authors: Tanoue Kyo , Shimada Kenshu
Published: September 2022

Jaw mechanics of lamniform sharks were examined three‐dimensionally to analyze the variability in jaw shape and the evolution of the jaw system based on the extant macrophagous species. Three‐dimensional lever analysis was applied to lamniform jaws to calculate bite force at each tooth relative to maximum input force from jaw adductor muscles for interspecific comparison of efficiency in lamniform jaws. When total input force from the jaw adductor muscles on both working and balancing sides of the skull is considered, input force varies along the jaw because the contribution by balancing side muscles is not constant. The phylogenetically basal‐most species,Mitsukurina owstoni, has the least efficient jaws due to posteriorly positioned jaw adductor muscles. Our study shows that the higher efficiency of jaws is regarded as apomorphic in lamniform phylogeny owing to the anterior extension of jaw adductor muscles relative toM. owstoniand a relative decrease in jaw length in relation to width seen in some species, both of which increase leverage. Differences in the efficiency of jaws among derived genera or species are due to the morphology of their jaws. The relationship between calculated bite force relative to maximum input force and tooth morphology indicates low relative bite forces being exerted at anteriorly located, narrow, piercing teeth, whereas high relative bite forces at posteriorly located, broad, cutting, or crushing‐type teeth. As a result, the biting pressure during feeding is maintained throughout the tooth series.