Genomic analysis of Tibetan ground tits identifies molecular adaptations associated with cooperative breeding.

Cooperative breeding is a sophisticated altruistic social behavior that helps social animals to adapt to harsh environments. The Tibetan ground tit, Pseudopodoces humilis, is a high-altitude bird endemic to the Tibetan plateau. Recently, it has become an exciting system for studying the evolution of facultative cooperative breeding. To test for molecular adaptations associated with cooperative breeding, we resequenced the whole genome of ground tits from 6 wild populations that display remarkable variation in the frequency of cooperative breeding. Population structure analyses showed that the 6 populations were divided into 4 lineages, which is congruent with the major geographical distribution of the sampling sites. Using genome-wide selective sweep analysis, we identified putative positively selected genes (PSGs) in groups of tits that displayed high and low cooperative breeding rates. The total number of PSGs varied from 146 to 722 in high cooperative breeding rate populations, and from 272 to 752 in low cooperative breeding rate populations. Functional enrichment analysis of these PSGs identified several significantly enriched ontologies related to oxytocin signaling, estrogen signaling, and insulin secretion. PSGs involved in these functional ontologies suggest that molecular adaptations in hormonal regulation may have played important roles in shaping the evolution of cooperative breeding in the ground tit. Taken together, our study provides candidate genes and functional ontologies involved in molecular adaptations associated with cooperative breeding in Tibetan ground tits, and calls for a better understanding of the genetic roles in the evolution of cooperative breeding.

Hypoxia-reprogramed megamitochondrion contacts and engulfs lysosome to mediate mitochondrial self-digestion.

Mitochondria are the key organelles for sensing oxygen, which is consumed by oxidative phosphorylation to generate ATP. Lysosomes contain hydrolytic enzymes that degrade misfolded proteins and damaged organelles to maintain cellular homeostasis. Mitochondria physically and functionally interact with lysosomes to regulate cellular metabolism. However, the mode and biological functions of mitochondria-lysosome communication remain largely unknown. Here, we show that hypoxia remodels normal tubular mitochondria into megamitochondria by inducing broad inter-mitochondria contacts and subsequent fusion. Importantly, under hypoxia, mitochondria-lysosome contacts are promoted, and certain lysosomes are engulfed by megamitochondria, in a process we term megamitochondria engulfing lysosome (MMEL). Both megamitochondria and mature lysosomes are required for MMEL. Moreover, the STX17-SNAP29-VAMP7 complex contributes to mitochondria-lysosome contacts and MMEL under hypoxia. Intriguingly, MMEL mediates a mode of mitochondrial degradation, which we termed mitochondrial self-digestion (MSD). Moreover, MSD increases mitochondrial ROS production. Our results reveal a mode of crosstalk between mitochondria and lysosomes and uncover an additional pathway for mitochondrial degradation.

Ultrafast and Low-Power 2D Bi2O2Se Memristors for Neuromorphic Computing Applications.

Memristors that emulate synaptic plasticity are building blocks for opening a new era of energy-efficient neuromorphic computing architecture, which will overcome the limitation of the von Neumann bottleneck. Layered two-dimensional (2D) Bi2O2Se, as an emerging material for next-generation electronics, is of great significance in improving the efficiency and performance of memristive devices. Herein, high-quality Bi2O2Se nanosheets are grown by configuring mica substrates face-down on the Bi2O2Se powder. Then, bipolar Bi2O2Se memristors are fabricated with excellent performance including ultrafast switching speed (<5 ns) and low-power consumption (<3.02 pJ). Moreover, synaptic plasticity, such as long-term potentiation/depression (LTP/LTD), paired-pulse facilitation (PPF), and spike-timing-dependent plasticity (STDP), are demonstrated in the Bi2O2Se memristor. Furthermore, MNIST recognition with simulated artificial neural networks (ANN) based on conductance modification could reach a high accuracy of 91%. Notably, the 2D Bi2O2Se enables the memristor to possess ultrafast and low-power attributes, showing great potential in neuromorphic computing applications.

Phylogenetic placement and species delimitation of the crab spider genus Phrynarachne (Araneae: Thomisidae) from China.

Evolutionary biologists have long been fascinated by the striking resemblance to bird droppings of the sit-and-wait crab spiders of the genus Phrynarachne. In doing so, species of Phrynarachne have evolved not to avoid detection, but rather, to cause predators to misidentify them as inedible and/or inanimate bird droppings. However, the lack of a phylogeny for Phrynarachne impedes our understanding of the evolution of this trait in the genus. Here we explore species boundaries in species of Phrynarachne from China using single- and multi-locus species delimitation approaches based on 30 Phrynarachne samples. All species delimitation approaches supported six species of Phrynarachne in China. We further present the first phylogenetic analysis of the genus Phrynarachne and estimate divergence times using two mitochondrial and three nuclear genes. All of our phylogenetic analyses supported the monophyly of Phrynarachne in China, with the genus still included within the higher 'Thomisus group' based on our results. Our dating analyses place the crown age of Phrynarachne in China to the middle Miocene. Taken together, our study provides a time-calibrated phylogeny of the genus Phrynarachne in China for testing hypotheses regarding the evolution of the lineage and bird dropping masquerade.

Enhanced Photoluminescence of Flexible InGaN/GaN Multiple Quantum Wells on Fabric by Piezo-Phototronic Effect.

Fabric-based wearable electronics are showing advantages in emerging applications in wearable devices, Internet of everything, and artificial intelligence. Compared to the one with organic materials, devices based on inorganic semiconductors (e.g., GaN) commonly show advantages of superior characteristics and high stability. Upon the transfer of GaN-based heterogeneous films from their rigid substrates onto flexible/fabric substrates, changes in strain would influence the device performance. Here, we demonstrate the transfer of InGaN/GaN multiple quantum well (MQW) films onto flexible/fabric substrates with an effective lift-off technique. The physical properties of the InGaN/GaN MQWs film are characterized by atomic force microscopy and high-resolution X-ray diffraction, indicating that the transferred film does not suffer from huge damage. Excellent flexible properties are observed in the film transferred on fabric, and the photoluminescence (PL) intensity is enhanced by the piezo-phototronic effect, which shows an increase of about 10% by applying an external strain with increasing the film curvature to 6.25 mm-1. Moreover, energy band diagrams of the GaN/InGaN/GaN heterojunction at different strains are illustrated to clarify the internal modulation mechanism by the piezo-phototronic effect. This work would facilitate the guidance of constructing high-performance devices on fabrics and also push forward the rapid development of flexible and wearable electronics.

Conspicuous cruciform silk decorations deflect avian predator attacks.

Although camouflage as an effective antipredator defense strategy is widespread across animals, highly conspicuous color patterning is not uncommon either. Many orb-web spiders adorn their webs with extra bright white silk. These conspicuous decorations are hypothesized to deter predators by warning the presence of sticky webs, camouflaging spiders, acting as a decoy, or intimidating predators by their apparent size. The decorations may also deflect predator attacks from spiders. However, empirical evidence for this deflection function remains limited. Here, we tested this hypothesis using the X-shaped silk cruciform decorations built by females of Argiope minuta. We employed visual modeling to quantify the conspicuousness of spiders and decorations from a perspective of avian predators. Then, we determined actual predation risk on spiders using naïve chicks as predators. Spider bodies and decorations were conspicuous against natural backgrounds to the avian visual systems. Chicks attacked the spider main bodies significantly less frequently on the decorated webs than on the undecorated webs, thus reducing predation risk. When both spiders and decorations were present, chicks also attacked the spider main bodies and their legs or decorations, and not randomly: they attacked the legs or decorations sooner and more frequently than they attacked the main bodies, independent of the ratio of the surface area between the decoration and spider size. Despite the increase in detectability, incorporating a conspicuous cruciform decoration to the web effectively defends the spider by diverting the attack toward the decoration or leg, but not by camouflaging or intimidating, thus, supporting the deflection hypothesis.

Local Adaptation of Bitter Taste and Ecological Speciation in a Wild Mammal.

Sensory systems are attractive evolutionary models to address how organisms adapt to local environments that can cause ecological speciation. However, tests of these evolutionary models have focused on visual, auditory, and olfactory senses. Here, we show local adaptation of bitter taste receptor genes in two neighboring populations of a wild mammal-the blind mole rat Spalax galili-that show ecological speciation in divergent soil environments. We found that basalt-type bitter receptors showed higher response intensity and sensitivity compared with chalk-type ones using both genetic and cell-based functional analyses. Such functional changes could help animals adapted to basalt soil select plants with less bitterness from diverse local foods, whereas a weaker reception to bitter taste may allow consumption of a greater range of plants for animals inhabiting chalk soil with a scarcity of food supply. Our study shows divergent selection on food resources through local adaptation of bitter receptors, and suggests that taste plays an important yet underappreciated role in speciation.

Effect of backside dry etching on the device performance of AlGaN/GaN HEMTs.

AlGaN/GaN heterojunction-based high-electron-mobility transistors (HEMTs) have significant advantages of high carrier concentration, high electron mobility, and large breakdown voltage, and show promising potential as power devices. Being widely used in semiconductor manufacturing, dry etching process is capable of fabricating microstructures and thinning substrate from backside, which is good for developing flexible devices. Here, we investigate the effect of backside dry etching of Si substrate on the physical and electrical properties of AlGaN/GaN HEMTs. The physical properties were characterized by scanning electron microscope, Raman spectra, and x-ray diffraction (XRD). After the dry etching process, the peak red-shift of GaNE2mode indicates an increase of tensile stress, and the XRD rocking curve of GaN film shows to a certain extent decreased dislocation density. Furthermore, the maximum saturation current density and maximum transconductance of the HEMTs are improved by 21.1% and 25.5%, respectively. The approach of backside dry etching for thinning Si substrate would contribute to the optimization of GaN heterojunction-based devices, and also provide inspirations for the development of flexible and robust power devices.

ACE2 receptor usage reveals variation in susceptibility to SARS-CoV and SARS-CoV-2 infection among bat species.

Bats are the suggested natural hosts for severe acute respiratory syndrome coronavirus (SARS-CoV) and the causal agent of the coronavirus disease 2019 (COVID-19) pandemic, SARS-CoV-2. The interaction of viral spike proteins with their host receptor angiotensin-converting enzyme 2 (ACE2) is a critical determinant of potential hosts and cross-species transmission. Here we use virus-host receptor binding and infection assays to examine 46 ACE2 orthologues from phylogenetically diverse bat species, including those in close and distant contact with humans. We found that 24, 21 and 16 of them failed to support infection by SARS-CoV, SARS-CoV-2 or both viruses, respectively. Furthermore, we confirmed that infection assays in human cells were consistent with those in two bat cell lines. Additionally, we used genetic and functional analyses to identify critical residues in bat ACE2 receptors associated with viral entry restrictions. Our results suggest that many bat species may not be the potential hosts of one or both viruses and that no correlation was identified between proximity to humans and probability of being natural hosts of SARS-CoV or SARS-CoV-2. This study demonstrates dramatic variation in susceptibility to SARS-CoV and SARS-CoV-2 infection among bat species and adds knowledge towards a better understanding of coronavirus-bat interaction.

Chain Conformation Control of Fluorene-Benzothiadiazole Copolymer Light-Emitting Diode Efficiency and Lifetime.

The ß-phase, in which the intermonomer torsion angle of a fraction of chain segments approaches ∼180°, is an intriguing conformational microstructure of the widely studied light-emitting polymer poly(9,9-dioctylfluorene) (PFO). Its generation can in turn be used to significantly improve the performance of PFO emission-layer-based light-emitting diodes (LEDs). Here, we report the generation of ß-phase chain segments in a copolymer, 90F8:10BT, containing 90% 9,9-dioctylfluorene (F8) and 10% 2,1,3-benzothiadiazole (BT) units and show that significant improvements in performance also ensue for LEDs with ß-phase 90F8:10BT emission layers, generalizing the earlier PFO results. The ß-phase was induced by both solvent vapor annealing and dipping copolymer thin films into a solvent/nonsolvent mixture. Subsequent absorption spectra show the characteristic fluorene ß-phase peak at ∼435 nm, but luminescence spectra (∼530 nm peak) and quantum yields barely change, with the emission arising following efficient energy transfer to the lowest-lying excited states localized in the vicinity of the BT units. For ∼5% ß-phase chain segment fraction relative to 0% ß-phase, the LED luminance at 10 V increased by ∼25% to 5940 cd m-2, the maximum external quantum efficiency by ∼61 to 1.91%, and the operational stability from 64% luminance retention after 20 h of operation to 90%. Detailed studies addressing the underlying device physics identify a reduced hole injection barrier, higher hole mobility, correspondingly more balanced electron and hole charge transport, and decreased carrier trapping as the dominant factors. These results confirm the effectiveness of chain conformation control for fluorene-based homo- and copolymer device optimization.

Diet and Adaptive Evolution of Alanine-Glyoxylate Aminotransferase Mitochondrial Targeting in Birds.

Adaptations to different diets represent a hallmark of animal diversity. The diets of birds are highly variable, making them an excellent model system for studying adaptive evolution driven by dietary changes. To test whether molecular adaptations to diet have occurred during the evolution of birds, we examined a dietary enzyme alanine-glyoxylate aminotransferase (AGT), which tends to target mitochondria in carnivorous mammals, peroxisomes in herbivorous mammals, and both mitochondria and peroxisomes in omnivorous mammals. A total of 31 bird species were examined in this study, which included representatives of most major avian lineages. Of these, 29 have an intact mitochondrial targeting sequence (MTS) of AGT. This finding is in stark contrast to mammals, which showed a number of independent losses of the MTS. Our cell-based functional assays revealed that the efficiency of AGT mitochondrial targeting was greatly reduced in unrelated lineages of granivorous birds, yet it tended to be high in insectivorous and carnivorous lineages. Furthermore, we found that proportions of animal tissue in avian diets were positively correlated with mitochondrial targeting efficiencies that were experimentally determined, but not with those that were computationally predicted. Adaptive evolution of AGT mitochondrial targeting in birds was further supported by the detection of positive selection on MTS regions. Our study contributes to the understanding of how diet drives molecular adaptations in animals, and suggests that caution must be taken when computationally predicting protein subcellular targeting.

[Effects of different fluid replenishment methods on internal environment, body thermal regulation response and severe heatstroke of 5-km armed cross-country training soldiers].

OBJECTIVE: To explore the effects of different fluid replenishment methods on the internal environment, body thermal regulatory response and severe heatstroke of 5-km armed cross-country training soldiers. METHODS: A Special Force officers and soldiers who participated in 5-km armed cross-country training (2-3 times a week, 25-30 minutes each time for 3 weeks) during summer training from June to July in 2018 were enrolled, and they were divided into three groups according to the random number table, with 300 trainees in each group. 200 mL of drinking fluids were given to each group 15 minutes before and after each 5-km armed cross-country training: A group with boiled water, B group with purified water, and C group with beverage prepared by pharmaceutical laboratory of the 990th Hospital of PLA Joint Logistics Support Force (100 mL containing 6 g carbohydrates, 42 mg sodium, and 11 mg potassium). The venous blood was collected before and after the last training or during the onset of severe heatstroke to do the following tests: serum cardiac troponin I (cTnI, chemiluminescence), MB isoenzyme of creatine kinase (CK-MB, immunosuppressive), serum creatinine (SCr, enzymatic method), urea nitrogen (BUN, enzymatic method), alanine aminotransferase (ALT, tryptase), aspartate transaminase (AST, tryptase), and Na+, K+, Cl- (electrode method). The heart rate (HR) and core temperature (Tc, anal temperature) were monitored at the same time. The amount of sweat in training and the occurrence of severe heatstroke were also recorded. RESULTS: There was no significant difference in heart, liver, kidney function, electrolyte and body heat regulation reaction among three groups of 5-km armed cross-country trainees before training. Compared with before training, the levels of serum cTnI, CK-MB, SCr, BUN, ALT, AST, HR and Tc were significantly increased after training or during the onset of severe heatstroke in three groups, while the contents of Na+, K+, Cl- were significantly decreased, but the increase or decrease of group C was relatively smaller compared with group A and group B [cTnI (µg/L): 0.9 (0.6, 1.4) vs. 1.1 (0.7, 2.8), 1.0 (0.6, 3.3); CK-MB (U/L): 7.0 (5.0, 11.0) vs. 9.0 (6.0, 14.5), 8.0 (6.0, 15.0); SCr (µmol/L): 92.09±18.64 vs. 102.78±18.77, 103.64±20.07; BUN (mmol/L): 7 (6, 9) vs. 9 (8, 11), 10 (8, 13); ALT (U/L): 27 (22, 34) vs. 36 (30, 43), 34 (27, 43); AST (U/L): 37 (31, 48) vs. 41 (34, 50), 39 (34, 51); HR (bpm): 87.01±17.07 vs. 95.88±21.06, 96.59±22.04; Tc (centigrade): 37.73±0.81 vs. 38.03±1.05, 38.10±1.04; Na+ (mmol/L): 150.14±3.86 vs. 144.18±8.89, 144.04±9.39; K+ (mmol/L): 4.32±0.57 vs. 4.15±0.62, 4.13±0.51; Cl- (mmol/L): 100.43±3.71 vs. 98.42±4.24, 98.41±4.58; all P < 0.01]. The incidence of severe heatstroke in group C was significantly lower than that in group A and group B [1.67% (5/300) vs. 5.00% (15/300), 5.33% (16/300), χ2 = 6.424, P = 0.040]. There was no significant difference in sweating volume in groups A, B, C (g: 370.47±48.71, 370.85±50.66, 370.17±50.21, F = 0.014, P = 0.986). There was no significant difference in the above indexes between group A and group B (all P > 0.05). Bi-classification Logistic regression analysis showed that the increase of HR, Tc and excessive loss of Na+, K+, Cl- were risk factors for severe heatstroke [odds ratio (OR) was 0.848, 0.138, 1.565, 17.996 and 2.328 respectively, all P < 0.01]. CONCLUSIONS: Timely supplementation of carbohydrate, sodium and potassium ions can effectively change the internal environment and body heat regulation reaction of 5-km armed cross-country trainees, so as to reduce the occurrence of severe heatstroke. The increases of HR, Tc and excessive loss of Na+, K+, Cl- are risk factors for severe heatstroke.

Synergistic Effect of Granular Seed Substrates and Soluble Additives in Structural Control of Prismatic CaCO3 Thin Films.

In biomineralization and bioinspired mineralization, substrates and additives function synergistically in providing structural control of the mineralized layers including their orientation, polymorph, morphology, hierarchical architecture, etc. Herein, a novel type of granular aragonitic CaCO3-poly(acrylic acid) substrate guides the mineralization of prismatic CaCO3 thin films of distinct morphology and polymorph in the presence of different additives including organic compounds and polymers. For instance, weakly charged amino acids lead to columnar aragonite overlayers, while their charged counterparts and organic acids/bases inhibit the overgrowth. Employment of several specific soluble polymer additives in overgrowth instead results in calcitic overlayers with distinct hierarchical architecture, good hardness/Young's modulus, and under-water superoleophobicity. Interestingly, self-organized patterns in the CaCO3-poly(l-glutamic acid) overlayer are obtained under proper mineralization conditions. We demonstrate that the granular seed comprised of mineralized and polymeric constituents is a versatile platform for obtaining prismatic CaCO3 thin films, where structural control can be realized by the employment of different types of additives in overgrowth. We expect the methodology to be applied to a broad spectrum of bioinspired, prismatic-type crystalline products, aiming for the development of high-performance hybrids.

Total morphosynthesis of biomimetic prismatic-type CaCO3 thin films.

Biomimetic mineralization can lead to advanced crystalline composites with common chemicals under ambient conditions. An exceptional example is biomimetic nacre with its superior fracture toughness. The synthesis of the prismatic layer with stiffness and wear resistance nonetheless remains an elusive goal. Herein, we apply a biomimetic mineralization method to grow prismatic-type CaCO3 thin films, mimicking their biogenic counterparts found in mollusk shells with a three-step pathway: coating a polymer substrate, deposition of a granular transition layer, and mineralization of a prismatic overlayer. The synthetic prismatic overlayers exhibit structural similarity and comparable hardness and Young's modulus to their biogenic counterparts. Furthermore, employment of a biomacromolecular soluble additive, silk fibroin, in fabrication of the prismatic thin films leads to micro-/nano-textures with enhanced toughness and emerging under-water superoleophobicity. This study highlights the crucial role of the granular transition layer in promoting competition growth of the prismatic layer.

Development and validation of a real-time reverse transcriptase PCR assay for sensitive detection of SFTSV.

BACKGROUND: Severe fever with thrombocytopenia syndrome bunyavirus (sftsv) is an emerging tick-borne rna virus recently identified as the pathogen that causes severe fever with thrombocytopenia syndrome (sfts) in china. the existing commercial nucleic acid testing (comnat) assay with a relatively high claimed limit of quantitative detection (loqd) is not capable of sensitive detection and quantitation of sftsv. Thus, a new real-time reverse transcriptase (rt)-pcr assay with improved sensitivity is needed for clinical diagnosis; it could also be used to screen blood donors if necessary. MATERIALS AND METHODS: We developed a new sftsv rt-pcr nat assay (newnat). About 129 plasma samples from 93 suspected sfts patients with typical clinical symptoms were tested using an anti-sftsv total antibody elisa and both comnat and newnat. The test performance of the two nat assays was evaluated and compared. RESULTS: The newnat had a lower limit for quantitative testing compared to comnat. Twelve samples were comnat negative but newnat positive. Out of 35 suspected sfts patients who were comnat negative and anti-sftsv total antibody negative, four tested positive by the newnat assay and one of these four seroconverted within 2-4 days after testing newnat positive. A high correlation was observed between the cts of the newnat and comnat assays. CONCLUSION: The newnat assay was sensitive for quantitative detection of sftsv and may be applicable to clinical diagnosis and studies of the need for blood donor screening.

[Comparison of the prognosis of intertrochanteric fracture with different surgical methods in elderly: a retrospective survival analysis].

OBJECTIVE: To determine the difference of post-operative mortality between ORIF (open reduction internal fixation) and hip replacement for the treatment of intertrochanteric fracture in elderly by using survival analysis. METHODS: The clinical data of 110 patients above 60 years old who underwent surgical treatment (ORIF or hip replacement) for the intertrochanteric fracture between April 2003 and May 2013 were retrospectively analyzed. Among the patients, 83 cases were treated with ORIF (ORIF group), there were 32 males and 51 females, aged from 61.44 to 98.75 years old with an average of (78.52 ± 7.98) years old; and 27 cases were treated with hip replacement (arthroplasty group), there were 8 males and 19 females, aged from 71.82 to 96.54 years old with an average of (79.99 ± 6.11) years old. A survival analysis was performed on the clinical data by using SPSS 110 software. The survival rate of 1-year,2-year, 5-year and the mean survival time for the total patients, the mortality rate of 1-year, 2-year in each group, the survival rate of 1-year, 2-year and mean survival time and survival curve in each group were included. RESULTS: All wounds achieved primary healing and no deaths were found in stay hospital. All patients were followed up from 1 to 125 months with an average of (46.93 ± 29.53) months. Among all 110 cases, 31 were dead and 79 survived. The survival rate of 1-year, 2-year and 5-year was (90.7 ± 2.8)%, (82.5 ± 3.9)% and (57.6 ± 6.5)%, respectively,while the ensemble mean survival time was (84.137 ± 5.902) months. The mortality rate of 1-year, 2-year in ORIF group was 7.2% and 12.0%, respectively; and in arthroplasty group, there was 14.8% and 25.9%, respectively. There was no significant difference in mortality rate of 1-year and 2-year between two groups. According to the survival analysis of the ORIF group, the survival rate of 1-year, 2-year was (92.6 ± 2.9)%, and (85.8 ± 4.3)%, respectively, and the mean survival time was (87.508 ± 6.063) months. In arthroplasty group, the survival rate of 1-year, 2-year was (85.2 ± 6.8)% and (73.9 ± 8.5)%,and the mean survival time was (67.294 ± 11.180) months. There was significant difference in mean survival time between two groups (P < 0.05). CONCLUSION: ORIF can achieve a better postoperative survival compare with hip replacement in treating intertrochanteric fracture in elderly.

Facile cellulose dissolution without heating in [C4mim][CH 3COO]/DMF solvent.

Novel cellulose solvents, [C4mim][CH3COO]/DMF, were designed by adding an aprotic polar solvent N,N-dimethylformamide (DMF) in 1-butyl-3-methylimidazolium acetate ([C4mim][CH3COO]). The solubilities of cellulose in [C4mim][CH3COO]/DMF solvents were determined at 25°C. The effects of molar ratio of DMF to [C4mim][CH3COO] on cellulose solubility and the possible dissolution mechanism of cellulose in [C4mim][CH3COO]/DMF solvent have been studied. Moreover, the regenerated cellulose from [C4mim][CH3COO]/DMF solvent were characterized by scanning electron micrograph (SEM) Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), and the degree of polymerization (DP) of regenerated cellulose was determined. The findings reveal that the facile dissolution of cellulose in such solvents is mainly attributed to the increased "free" [CH3COO](-) anions and [C4mim](+) cations which result from the dissociation of [C4mim][CH3COO] by DMF. Moreover, the macromolecular chain of the cellulose is hardly broken during the dissolution and precipitation processes.

Impaired ossification coupled with accelerated cartilage degeneration in developmental dysplasia of the hip: evidences from µCT arthrography in a rat model.

BACKGROUND: Developmental dysplasia of the hip (DDH) always leads to cartilage degeneration and osteoarthritis of the hip joint. However, the diagnosis of early cartilage degeneration in DDH is still a clinical challenge. This study aims to investigate the dynamic changes of bone and cartilage in the hip of a rat model of DDH and to explore the potential application of microcomputed tomography (µCT) arthrography to detect early cartilage degeneration in DDH. METHODS: Newborn Wistar rats were used to induce DDH by hindlimb swaddling. The bone and cartilage of the hip in model and control group were analyzed by µCT arthrography and histology examination at postnatal day 10, week 4, 6 and 8. RESULTS: Hip dysplasia developed with age, became obvious at postnatal week 6 and further progressed at week 8. µCT analysis showed that bone mineral density (BMD) and bone volume density (bone volume over total volume, BV/TV) of the femoral head and neck region (FHNR) in model group were both significantly lower than those in control group, and they increased dramatically from postnatal week 4 to week 6 but maintained at a similar level at week 8. Contrast-enhanced µCT (CE-µCT) arthrography and histology data showed age-dependent increase in cartilage attenuation (CA) and decrease in safranin O staining intensity (SI) in model group, respectively. Moreover, the model group revealed remarkably higher CA and lower SI than control group, respectively. In addition, significant changes of CA and SI were both observed from postnatal week 6 to week 8 in model group. A strong linear correlation (r2=0.789, P <0.001) was found between CA and SI in model group. Furthermore, BMD was negatively correlated with SI (t=-2.683, P <0.05), whereas specific bone surface (bone surface over bone volume, BS/BV) was positively correlated with SI (t =4.501, P <0.01), in model group. CONCLUSIONS: Impaired ossification coupled with continuous loss of sGAG in cartilage matrix was found in the dysplasia hip during the disease progression of DDH. Cartilage degeneration in the dysplasia hip may occur early at childhood, accelerated with age and become irreversible at young adult stage. All these abnormal changes could be quantitatively assessed by µCT arthrography.