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This paper reports on the NTIRE 2024 Quality Assessment of AI-Generated Content Challenge, which will be held in conjunction with the New Trends in Image Restoration and Enhancement Workshop (NTIRE) at CVPR 2024. This challenge is to address a major challenge in the field of image and video processing, namely, Image Quality Assessment (IQA) and Video Quality Assessment (VQA) for AI-Generated Content (AIGC). The challenge is divided into the image track and the video track. The image track uses the AIGIQA-20K, which contains 20,000 AI-Generated Images (AIGIs) generated by 15 popular generative models. The image track has a total of 318 registered participants. A total of 1,646 submissions are received in the development phase, and 221 submissions are received in the test phase. Finally, 16 participating teams submitted their models and fact sheets. The video track uses the T2VQA-DB, which contains 10,000 AI-Generated Videos (AIGVs) generated by 9 popular Text-to-Video (T2V) models. A total of 196 participants have registered in the video track. A total of 991 submissions are received in the development phase, and 185 submissions are received in the test phase. Finally, 12 participating teams submitted their models and fact sheets. Some methods have achieved better results than baseline methods, and the winning methods in both tracks have demonstrated superior prediction performance on AIGC.

Objective: The male preponderance in prevalence of autism is among the most pronounced sex ratios across neurodevelopmental conditions. The authors sought to elucidate the relationship between autism and typical sex-differential neuroanatomy, cognition, and related gene expression. Methods: Using a novel deep learning framework trained to predict biological sex based on T1-weighted structural brain images, the authors compared sex prediction model performance across neurotypical and autistic males and females. Multiple large-scale data sets comprising T1-weighted MRI data were employed at four stages of the analysis pipeline: 1) pretraining, with the UK Biobank sample (>10,000 individuals); 2) transfer learning and validation, with the ABIDE data sets (1,412 individuals, 5–56 years of age); 3) test and discovery, with the EU-AIMS/AIMS-2-TRIALS LEAP data set (681 individuals, 6–30 years of age); and 4) specificity, with the NeuroIMAGE and ADHD200 data sets (887 individuals, 7–26 years of age). Results: Across both ABIDE and LEAP, features positively predictive of neurotypical males were on average significantly more predictive of autistic males (ABIDE: Cohen’s d=0.48; LEAP: Cohen’s d=1.34). Features positively predictive of neurotypical females were on average significantly less predictive of autistic females (ABIDE: Cohen’s d=1.25; LEAP: Cohen’s d=1.29). These differences in sex prediction accuracy in autism were not observed in individuals with ADHD. In autistic females, the male-shifted neurophenotype was further associated with poorer social sensitivity and emotional face processing while also associated with gene expression patterns of midgestational cell types. Conclusions: The results demonstrate an increased resemblance in both autistic male and female individuals’ neuroanatomy with male-characteristic patterns associated with typically sex-differential social cognitive features and related gene expression patterns. The findings hold promise for future resear

The recursive intra-frame block partitioning decision process, a crucial component of the next-generation video coding standards, exerts significant influence over the encoding time. In this paper, we propose an encoder-decoder neural network (NN) to accelerate this process. Specifically, a CNN is utilized to compress the pixel data of the largest coding unit (LCU) into a fixed-length vector. Subsequently, a Transformer decoder is employed to transcribe the fixed-length vector into a variable-length vector, which represents the block partitioning outcomes of the encoding LCU. The vector transcription process adheres to the constraints imposed by the block partitioning algorithm. By fully parallelizing the NN prediction in the intra-mode decision, substantial time savings can be attained during the decision phase. The experimental results obtained from high-definition (HD) sequences coding demonstrate that this framework achieves a remarkable 87.84\% reduction in encoding time, with a relatively small loss (8.09\%) of coding performance compared to AVS3 HPM4.0.

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Atomically defined nanographenes (NGs) feature size-dependent energy gaps induced by, and tuneable through, quantum confinement. Their energy-tunability and robustness make NGs appealing candidates as active elements in sensitized geometries, where NGs functionalize a metal oxide (MO) film with large-area-to-volume ratio. Despite the prominent relevance of NG/MO interfaces for developing novel architectures for solar energy conversion, to date, little information is available regarding the fundamentals of electron transfer (ET) processes taking place from NG donors to MO acceptors. Here, we analyze the interplay between the size of atomically precise NGs and ET dynamics at NG/MO interfaces. We observe that as the size of NG decreases, ET from the NG donating state to the MO acceptor state speeds up. This dependence can be rationalized from variations in the donor-to-acceptor interfacial overpotential as the NG size (HOMO–LUMO gap) is reduced (increased), and can be rationalized within the framework of Marcus ET theory., source:https://pubs.rsc.org/en/content/articlelanding/2020/nr/d0nr03891a

Graphene has demonstrated great potential in new-generation electronic applications due to its unique electronic properties such as large carrier Fermi velocity, ultrahigh carrier mobility, and high material stability. Interestingly, the electronic structures can be further engineered in multilayer graphene by the introduction of a twist angle between different layers to create van Hove singularities (vHSs) at adjustable binding energy. In this work, using angle-resolved photoemission spectroscopy with sub-micrometer spatial resolution, the band structures and their evolution are systematically studied with twist angle in bilayer and trilayer graphene sheets. A doping effect is directly observed in graphene multilayer system as well as vHSs in bilayer graphene over a wide range of twist angles (from 5° to 31°) with wide tunable energy range over 2 eV. In addition, the formation of multiple vHSs (at different binding energies) is also observed in trilayer graphene. The large tuning range of vHS binding energy in twisted multilayer graphene provides a promising material base for optoelectrical applications with broadband wavelength selectivity from the infrared to the ultraviolet regime, as demonstrated by an example application of wavelength selective photodetector.

Graphene has demonstrated great potential in new-generation electronic applications due to its unique electronic properties such as large carrier Fermi velocity, ultrahigh carrier mobility, and high material stability. Interestingly, the electronic structures can be further engineered in multilayer graphene by the introduction of a twist angle between different layers to create van Hove singularities (vHSs) at adjustable binding energy. In this work, using angle-resolved photoemission spectroscopy with sub-micrometer spatial resolution, the band structures and their evolution are systematically studied with twist angle in bilayer and trilayer graphene sheets. A doping effect is directly observed in graphene multilayer system as well as vHSs in bilayer graphene over a wide range of twist angles (from 5° to 31°) with wide tunable energy range over 2 eV. In addition, the formation of multiple vHSs (at different binding energies) is also observed in trilayer graphene. The large tuning range of vHS binding energy in twisted multilayer graphene provides a promising material base for optoelectrical applications with broadband wavelength selectivity from the infrared to the ultraviolet regime, as demonstrated by an example application of wavelength selective photodetector.

In recent years, using a network of autonomous and cooperative unmanned aerial vehicles (UAVs) without command and communication from the ground station has become more imperative, in particular in search-and-rescue operations, disaster management, and other applications where human intervention is limited. In such scenarios, UAVs can make more efficient decisions if they acquire more information about the mobility, sensing and actuation capabilities of their neighbor nodes. In this paper, we develop an unsupervised online learning algorithm for joint mobility prediction and object profiling of UAVs to facilitate control and communication protocols. The proposed method not only predicts the future locations of the surrounding flying objects, but also classifies them into different groups with similar levels of maneuverability (e.g. rotatory, and fixed-wing UAVs) without prior knowledge about these classes. This method is flexible in admitting new object types with unknown mobility profiles, thereby applicable to emerging flying Ad-hoc networks with heterogeneous nodes., Comment: 8 pages, 11 figures

http://archive.org/details/dynamicscontrolo00wang, NA

http://archive.org/details/dynamicsndcontro1094525860, NA

Novel fluorene-based poly( aromatic diacetylene)s have been synthesized by CuCl-catalyzed oxidative coupling of aromatic diynes. New aromatic diynes 2,7-diethynyl- 9,9-bis(triphenylamine) fluorene ( M-1) is synthesized by multistep reactions. The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, UV, photoluminescence ( PL), and cyclic voltammetry analyses. These polymers possess good thermal stability. All the polymers are completely soluble in coammon solvents such as toluene, THF, chloroform, and dichloromethane. The polymers exhibit strong blue photoluminescence in solution and green photoluminescence in the solid state. The polymer containing triphenylamine-substituted fluorene has lower oxidation potential (-5.45 eV) than the previous polyfluorenes (-5.80 eV).

Novel fluorene-based poly( aromatic diacetylene)s have been synthesized by CuCl-catalyzed oxidative coupling of aromatic diynes. New aromatic diynes 2,7-diethynyl- 9,9-bis(triphenylamine) fluorene ( M-1) is synthesized by multistep reactions. The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, UV, photoluminescence ( PL), and cyclic voltammetry analyses. These polymers possess good thermal stability. All the polymers are completely soluble in coammon solvents such as toluene, THF, chloroform, and dichloromethane. The polymers exhibit strong blue photoluminescence in solution and green photoluminescence in the solid state. The polymer containing triphenylamine-substituted fluorene has lower oxidation potential (-5.45 eV) than the previous polyfluorenes (-5.80 eV).

Novel fluorene-based poly( aromatic diacetylene)s have been synthesized by CuCl-catalyzed oxidative coupling of aromatic diynes. New aromatic diynes 2,7-diethynyl- 9,9-bis(triphenylamine) fluorene ( M-1) is synthesized by multistep reactions. The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, UV, photoluminescence ( PL), and cyclic voltammetry analyses. These polymers possess good thermal stability. All the polymers are completely soluble in coammon solvents such as toluene, THF, chloroform, and dichloromethane. The polymers exhibit strong blue photoluminescence in solution and green photoluminescence in the solid state. The polymer containing triphenylamine-substituted fluorene has lower oxidation potential (-5.45 eV) than the previous polyfluorenes (-5.80 eV).

New hyperbranched poly(aryleneethynylene)s containing carbazole moieties are synthesized in high yields (up to 87\%) by polycyclotrimerization of 3,6-bis(4-ethynylphenyl)-9-octylcarbazole and its copolymerization with 1-octyne catalyzed by CpCo(CO)(2) in THF. The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, UV, photoluminescence, and cyclic voltammetry analyses. All the polymers are soluble in common organic solvents and show outstanding thermal stability (>= 430 degrees C). They graphitize in high yields (up to 79\%) when pyrolyzed at 800 degrees C. Upon photoexcitation, the polymers emit a strong deep blue light of ca. 400 nm with quantum yields larger than 60\%.

New hyperbranched poly(aryleneethynylene)s containing carbazole moieties are synthesized in high yields (up to 87\%) by polycyclotrimerization of 3,6-bis(4-ethynylphenyl)-9-octylcarbazole and its copolymerization with 1-octyne catalyzed by CpCo(CO)(2) in THF. The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, UV, photoluminescence, and cyclic voltammetry analyses. All the polymers are soluble in common organic solvents and show outstanding thermal stability (>= 430 degrees C). They graphitize in high yields (up to 79\%) when pyrolyzed at 800 degrees C. Upon photoexcitation, the polymers emit a strong deep blue light of ca. 400 nm with quantum yields larger than 60\%.

New hyperbranched poly(aryleneethynylene)s containing carbazole moieties are synthesized in high yields (up to 87\%) by polycyclotrimerization of 3,6-bis(4-ethynylphenyl)-9-octylcarbazole and its copolymerization with 1-octyne catalyzed by CpCo(CO)(2) in THF. The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, UV, photoluminescence, and cyclic voltammetry analyses. All the polymers are soluble in common organic solvents and show outstanding thermal stability (>= 430 degrees C). They graphitize in high yields (up to 79\%) when pyrolyzed at 800 degrees C. Upon photoexcitation, the polymers emit a strong deep blue light of ca. 400 nm with quantum yields larger than 60\%.

M.Alekhnovich et al. recently have proposed a model of algorithms, called BT model, which covers Greedy, Backtrack and Simple Dynamic Programming methods and can be further divided into fixed, adaptive and fully adaptive three kinds, and have proved exponential time lower bounds of exact and approximation algorithms under adaptive BT model for Knapsack problem which are $\Omega(2^{n/2}/\sqrt n)=\Omega(2^{0.5n}/\sqrt n)$ and $\Omega((1/\epsilon)^{1/3.17})\approx\Omega((1/\epsilon)^{0.315})$(for approximation ratio $1-\epsilon$) respectively (M. Alekhovich, A. Borodin, J. Buresh-Oppenheim, R. Impagliazzo, A. Magen, and T. Pitassi, Toward a Model for Backtracking and Dynamic Programming, \emph{Proceedings of Twentieth Annual IEEE Conference on Computational Complexity}, pp308-322, 2005). In this note, we slightly improved their lower bounds to $\Omega(2^{(2-\epsilon)n/3}/\sqrt{n})\approx \Omega(2^{0.66n}/\sqrt{n})$ and $\Omega((1/\epsilon)^{1/2.38})\approx\Omega((1/\epsilon)^{0.420})$, and proposed as an open question what is the best achievable lower bounds for knapsack under adaptive BT models., Comment: 9 pages, 3 figures

New hyperbranched polyarylenes of high molecular weights are synthesized in high yields by copolycyclotrimerizations of diynes 1,4-diethynylbenzene, 4,4'-diethynylbiphenyl, 2,7-diethynylfluorene and 2,5-diethynylthiophene with monoynes 1-heptyne, 1-octyne and 1-dodecyne catalyzed by TaCl5-Ph4Sn in toluene. All the polymers show good solubility in common organic solvents, possess excellent thermal stability, and emit strong deep-blue lights of similar to 400 nm with quantum efficiencies up to 98\%. The polyarylenes effectively limit 532 nm lasers light, some of which show optical limiting performances superior to that of C-60, a well-known optical limiter. (c) 2005 Elsevier Ltd. All rights reserved.

Alkyne copolycyclomerizations of aromatic diynes 2,7-bis(4-ethynylphenylethynyl)-9,9-diliexylfluorene (1) and I 4-bis(4-ethynylphenylethynyl) benzene (11) with an aliphatic moncyne 1-dodecyne (A) were effected by CPCO(CO)(2)-hv in THF, producing hyperbranched poly(aryleneethynylene)s 1 and 2) Of high molecular weights (M, up to 4.4 x 10(4) Da) in high isolation yields (up to 97\%). The polymers possessed outstanding thermal stability and emitted strong deep blue light of; 400 nm when their solutions were photoexcited. The polymers effectively limited the light of a 532 nm laser, with the performance of 2 being better than that Of C-60, a well-known optical limiter, under similar linear transmittance.

Alkyne copolycyclomerizations of aromatic diynes 2,7-bis(4-ethynylphenylethynyl)-9,9-diliexylfluorene (1) and I 4-bis(4-ethynylphenylethynyl) benzene (11) with an aliphatic moncyne 1-dodecyne (A) were effected by CPCO(CO)(2)-hv in THF, producing hyperbranched poly(aryleneethynylene)s 1 and 2) Of high molecular weights (M, up to 4.4 x 10(4) Da) in high isolation yields (up to 97\%). The polymers possessed outstanding thermal stability and emitted strong deep blue light of; 400 nm when their solutions were photoexcited. The polymers effectively limited the light of a 532 nm laser, with the performance of 2 being better than that Of C-60, a well-known optical limiter, under similar linear transmittance.

New hyperbranched polyarylenes of high molecular weights are synthesized in high yields by copolycyclotrimerizations of diynes 1,4-diethynylbenzene, 4,4'-diethynylbiphenyl, 2,7-diethynylfluorene and 2,5-diethynylthiophene with monoynes 1-heptyne, 1-octyne and 1-dodecyne catalyzed by TaCl5-Ph4Sn in toluene. All the polymers show good solubility in common organic solvents, possess excellent thermal stability, and emit strong deep-blue lights of similar to 400 nm with quantum efficiencies up to 98\%. The polyarylenes effectively limit 532 nm lasers light, some of which show optical limiting performances superior to that of C-60, a well-known optical limiter. (c) 2005 Elsevier Ltd. All rights reserved.

Alkyne copolycyclomerizations of aromatic diynes 2,7-bis(4-ethynylphenylethynyl)-9,9-diliexylfluorene (1) and I 4-bis(4-ethynylphenylethynyl) benzene (11) with an aliphatic moncyne 1-dodecyne (A) were effected by CPCO(CO)(2)-hv in THF, producing hyperbranched poly(aryleneethynylene)s 1 and 2) Of high molecular weights (M, up to 4.4 x 10(4) Da) in high isolation yields (up to 97\%). The polymers possessed outstanding thermal stability and emitted strong deep blue light of; 400 nm when their solutions were photoexcited. The polymers effectively limited the light of a 532 nm laser, with the performance of 2 being better than that Of C-60, a well-known optical limiter, under similar linear transmittance.

New hyperbranched polyarylenes of high molecular weights are synthesized in high yields by copolycyclotrimerizations of diynes 1,4-diethynylbenzene, 4,4'-diethynylbiphenyl, 2,7-diethynylfluorene and 2,5-diethynylthiophene with monoynes 1-heptyne, 1-octyne and 1-dodecyne catalyzed by TaCl5-Ph4Sn in toluene. All the polymers show good solubility in common organic solvents, possess excellent thermal stability, and emit strong deep-blue lights of similar to 400 nm with quantum efficiencies up to 98\%. The polyarylenes effectively limit 532 nm lasers light, some of which show optical limiting performances superior to that of C-60, a well-known optical limiter. (c) 2005 Elsevier Ltd. All rights reserved.

A germole-containing diacetylene, 1,1-diethynyl-2,3,4,5-tetraphenylgermole ( 2), was synthesized. Homopolymerization of 2 and its copolycyclotrimerization with 1-octyne were effected by TaCl5 - Ph4Sn in toluene, producing completely soluble polymers ( 1) in moderate yields. The molecular structure of 1 was characterized by spectroscopic methods. The thermal stability of 1 was evaluated by thermogravimetric analysis, which detected virtually no weight loss when the polymers were heated to similar to350degreesC. These hyperbranched polymers were electronically conjugated as suggested by their strong absorption in the visible spectral region (lambda(max) similar to 540 nm). Photoluminescence of the polymers was dramatically enhanced by cooling their solutions to low temperatures. Restricted intramolecular rotations of the phenyl rings upon the axes of the single bonds linked to the germole cores at the cryogenic temperatures might be responsible for this unique phenomenon of cooling-enhanced emission.

Hyperbranched polyarylenes and polyynes with high molecular weights (up to 1 x 106) are prepared in high yields (up to 99.9%) by alkyne polycyclotrimerization and polycoupling. All the polymers exhibit low intrinsic viscosities and outstanding thermal stabilities, losing little of their weights when heated to > 400 DGC. The polymers graphitize or ceramize at temperatures > 800 DGC in high yields (up to 86%). Poly(arylphenylene)s emit strong deep-blue to blue-green light with fluorescence quantum yields up to 98%. They strongly attenuate intense laser pulses, with their optical power-limiting performances superior to that of [60]fullerene, a wellknown optical limiter. The polycyclotrimerization of bis(aryl ethynyl ketone)s initiated by secondary amine gives regioregular hyperbranched poly(aroylarylene)s, which can be readily cross-linked by UV irradiation. Cu-catalyzed alkyne polycoupling yields hyperbranched polyynes, whose thin films exhibit high refractive indexes. Their internal and terminal acetylene moieties readily form complexes with metal carbonyls, which can be transformed to soft ferromagnetic ceramics with high magnetic susceptibilities (MS up to -118 emu/g).

Liquid-crystalline and light-emitting poly(2-alkyne)s and poly(1-phenyl-1-alkyne)s containing biphenyl (Biph) cores, alkyl spacers, and alkoxy tails (-{RC=C[(CH2)(m)-OCO-Biph-OC7H15]}(n)-, where R, m = CH3, 4 [P1(4)]; CH3, 9 [P1(9)]; C6H5, 4 [P2(4)]; and C6H5, 9 [P2(9)]\}, were synthesized and the effects of the spacer length and backbone structure on the properties of the polymers were investigated. The disubstituted acetylene monomers [1(m) and 2(m) (m = 4, 9)] were prepared by esterification of biphenylcarboxylic acid (6) with omega-alkynyl alcohols [4(m) or 5(m)]. Polymerizations of 1(m) and 2(m) were effected by WCl6-, MOCl5-, and NbCl5-Ph4Sn and the reactions catalyzed by WCl6-P(h)4Sn under optimal conditions produce polymers P1(m) and P2(m) with high molecular weights (M-w, up to 3.1 x 10(5)) in good yields (up to 81\%). The structures and properties of the disubstituted polyacetylenes were characterized and evaluated by nuclear magnetic resonance (NMR), thermogravimetry (TGA), differential scanning calorimetry (DSC), polarized optical microscope (POM), X-ray diffraction (XRD), ultraviolet spectroscopy (UV), and photoluminescence (PL) analyses. The polymers are resistant to thermolysis (Td greater than or equal to 360 degreesC) and all but P2(4) exhibit liquid crystallinity at elevated temperatures. The polymers with long methylene spacers, that is, P1(9) and P2(9), form a smectic A (SmA) mesophase with a monolayer arrangement. Upon excitation, strong UV and blue emissions peaking at 369 and 460 nm are observed in P1(m) and P2(m), respectively, whose quantum yields are found to increase with the spacer lengths.

The poly(C-60-co-styrene)s prepared by radical copolymerizations of C-60 and styrene in bulk were characterized by multiple-detector size-exclusion chromatographs consisting of a refractometer, a differential viscometer, and/or a right-angle laser-light scattering photometer. The multidetector systems enabled the determinations of reliable, absolute molecular weights of the copolymers. The plots of intrinsic viscosity vs. molecular weight and radius of gyration vs. molecular weight offered valuable information about the molecular architectures of the copolymers. The slopes of the plots reveal that the structure of the copolymer changes with its C-60 content: the copolymer with a low C-60 content of 0.58 wt\% possesses a linear structure, whereas its conger with a high C-60 content of 1.14 wt\% possesses a branched structure. (C) 2004 Elsevier Ltd. All rights reserved.

Alkyne polymerizations are effected by tungsten- and tantalum-based catalysts, giving linear polyacetylenes (LPAs) and hyperbranched polyarylenes (HPAs) of high molecular weights (M-w up to 2.5 x 10(5)) in high yields (up to 93\%). All the LPAs and HPAs are thermally stable and completely soluble in common solvents such as THF, toluene, dichloromethane, and chloroform. Incorporation of biphenyl mesogenic pendants into poly(1-phenyl-1-hexyne) structure endows the LCPA with nematicity. Upon photoexcitation, the LPAs and HPAs emit strong UV and blue lights with high quantum yields (up to 94\%). Multi-layer electroluminescence devices of LPAs emit blue light with maximum luminance and external quantum efficiency of 1065 cd/m(2) and 0.86\%, respectively. The HPAs attenuate strong laser pulses, with optical limiting performances comparable to that of C-60, a well-known optical limiter.

Organometallic polymers consisting of three-dimensionally alternating ferrocene and silyne units are synthesized in high yields by a one-pot procedure of coupling reactions. The hyperbranched polymers are electronically conjugated, with their absorption spectra extending into the infrared region. The polymers ceramize when pyrolyzed, with higher temperatures favoring the formation of ceramics with larger metallic nanoclusters. The ceramics containing iron silicide nanocrystals exhibit outstanding soft ferromagnetisms with excellent magnetic susceptibilities and practically nil hysteresis losses.

At present time techniques in preparing advanced ceramic materials with high electrical conductivity and magnetic susceptibility are rare. This new invention relates to hyperbranched organometallic polymers, which are useful as precursors to certain ceramic materials, processes for the preparation of such polymers and the preparation of ceramic materials from such polymers, ceramic materials and their use as ferromagnetic materials and electrically conductive materials. This Hyperbranched organometallic polymers are synthesized through the polymerization of dilithioferrocene and trichloroalkylsilanes. Pyrolysis of the hyperbranched polymers yields mesoporous, conductive, and magnetic ceramics. The three-dimensional structure of the hyperbranched polymers serves as shielding nets to keep the atom inside thereby enabling the high-yield production of the ceramic materials. Most of the hyperbranched polymer presursors of the invention are soluable in common solvents, melt at relatively low temperatures and can be processed into robust engineering forms such as thin films, which is different from the crosslinking polymer presursors as they are inherent intractable. The high iron content and the nanodimension of the iron clusters endow the ceramics with high electrical conductivity and superparamagnetic susceptibility. The saturation magnetizability of the ceramics is much higher than that from the linear polymers and the hysteresis loss is virtually zero, which means the ceramics are excellent soft ferromagnetic materials.

At present time techniques in preparing advanced ceramic materials with high electrical conductivity and magnetic susceptibility are rare. This new invention relates to hyperbranched organometallic polymers, which are useful as precursors to certain ceramic materials, processes for the preparation of such polymers and the preparation of ceramic materials from such polymers, ceramic materials and their use as ferromagnetic materials and electrically conductive materials. This Hyperbranched organometallic polymers are synthesized through the polymerization of dilithioferrocene and trichloroalkylsilanes. Pyrolysis of the hyperbranched polymers yields mesoporous, conductive, and magnetic ceramics. The three-dimensional structure of the hyperbranched polymers serves as shielding nets to keep the atom inside thereby enabling the high-yield production of the ceramic materials. Most of the hyperbranched polymer presursors of the invention are soluable in common solvents, melt at relatively low temperatures and can be processed into robust engineering forms such as thin films, which is different from the crosslinking polymer presursors as they are inherent intractable. The high iron content and the nanodimension of the iron clusters endow the ceramics with high electrical conductivity and superparamagnetic susceptibility. The saturation magnetizability of the ceramics is much higher than that from the linear polymers and the hysteresis loss is virtually zero, which means the ceramics are excellent soft ferromagnetic materials.

Liquid-crystalline and light-emitting poly(2-alkyne)s and poly(1-phenyl-1-alkyne)s containing biphenyl (Biph) cores, alkyl spacers, and alkoxy tails (-{RC=C[(CH2)(m)-OCO-Biph-OC7H15]}(n)-, where R, m = CH3, 4 [P1(4)]; CH3, 9 [P1(9)]; C6H5, 4 [P2(4)]; and C6H5, 9 [P2(9)]\}, were synthesized and the effects of the spacer length and backbone structure on the properties of the polymers were investigated. The disubstituted acetylene monomers [1(m) and 2(m) (m = 4, 9)] were prepared by esterification of biphenylcarboxylic acid (6) with omega-alkynyl alcohols [4(m) or 5(m)]. Polymerizations of 1(m) and 2(m) were effected by WCl6-, MOCl5-, and NbCl5-Ph4Sn and the reactions catalyzed by WCl6-P(h)4Sn under optimal conditions produce polymers P1(m) and P2(m) with high molecular weights (M-w, up to 3.1 x 10(5)) in good yields (up to 81\%). The structures and properties of the disubstituted polyacetylenes were characterized and evaluated by nuclear magnetic resonance (NMR), thermogravimetry (TGA), differential scanning calorimetry (DSC), polarized optical microscope (POM), X-ray diffraction (XRD), ultraviolet spectroscopy (UV), and photoluminescence (PL) analyses. The polymers are resistant to thermolysis (Td greater than or equal to 360 degreesC) and all but P2(4) exhibit liquid crystallinity at elevated temperatures. The polymers with long methylene spacers, that is, P1(9) and P2(9), form a smectic A (SmA) mesophase with a monolayer arrangement. Upon excitation, strong UV and blue emissions peaking at 369 and 460 nm are observed in P1(m) and P2(m), respectively, whose quantum yields are found to increase with the spacer lengths.

The poly(C-60-co-styrene)s prepared by radical copolymerizations of C-60 and styrene in bulk were characterized by multiple-detector size-exclusion chromatographs consisting of a refractometer, a differential viscometer, and/or a right-angle laser-light scattering photometer. The multidetector systems enabled the determinations of reliable, absolute molecular weights of the copolymers. The plots of intrinsic viscosity vs. molecular weight and radius of gyration vs. molecular weight offered valuable information about the molecular architectures of the copolymers. The slopes of the plots reveal that the structure of the copolymer changes with its C-60 content: the copolymer with a low C-60 content of 0.58 wt\% possesses a linear structure, whereas its conger with a high C-60 content of 1.14 wt\% possesses a branched structure. (C) 2004 Elsevier Ltd. All rights reserved.