Induced neural stem cells regulate microglial activation through Akt-mediated upregulation of CXCR4 and Crry in a mouse model of closed head injury

Microglial activation that occurs rapidly after closed head injury may play important and complex roles in neuroinflammation-associated neuronal damage and repair.We previously reported that induced neural stem cells can modulate the behavior of activated microglia via CXCL12/CXCR4 signaling,influencing their activation such that they can promote neurological recovery.However,the mechanism of CXCR4 upregulation in induced neural stem cells remains unclear.In this study,we found that nuclear factor-κB activation induced by closed head injury mouse serum in microglia promoted CXCL12 and tumor necrosis factor-αexpression but suppressed insulin-like growth factor-1 expression.However,recombinant complement receptor 2-conjugated Crry(CR2-Crry)reduced the effects of closed head injury mouse serum-induced nuclear factor-κB activation in microglia and the levels of activated microglia,CXCL12,and tumor necrosis factor-α.Additionally,we observed that,in response to stimulation(including stimulation by CXCL12 secreted by activated microglia),CXCR4 and Crry levels can be upregulated in induced neural stem cells via the interplay among CXCL12/CXCR4,Crry,and Akt signaling to modulate microglial activation.In agreement with these in vitro experimental results,we found that Akt activation enhanced the immunoregulatory effects of induced neural stem cell grafts on microglial activation,leading to the promotion of neurological recovery via insulin-like growth factor-1 secretion and the neuroprotective effects of induced neural stem cell grafts through CXCR4 and Crry upregulation in the injured cortices of closed head injury mice.Notably,these beneficial effects of Akt activation in induced neural stem cells were positively correlated with the therapeutic effects of induced neural stem cells on neuronal injury,cerebral edema,and neurological disorders post–closed head injury.In conclusion,our findings reveal that Akt activation may enhance the immunoregulatory effects of induced neural stem cells on microglial activation via upregulation of CXCR4 and Crry,thereby promoting induced neural stem cell–mediated improvement of neuronal injury,cerebral edema,and neurological disorders following closed head injury.

ARF4 acting upstream of LBD16 promotes adventitious root formation in peach

Although class A auxin response factors(ARFs)are known to regulate adventitious root(AR)development through the canonical SCFTIR1-Aux/IAA-ARF signaling pathway,the regulatory role of class B ARFs in AR development remains largely unclear.Therefore,this research focused on the role of class B ARF transcription factors in peach(Prunus persica‘Shengli')adventitious root formation.Here,we report the role of a class B ARF gene Pp ARF4 in adventitious root formation in peach.Comparative transcriptome and q RT-PCR analyses showed that the transcription of Pp ARF4 was significantly up-regulated in auxin-treated stem explants.Y2H assay showed that Pp ARF4 had no interaction with Pp IAAs(AUXIN/INDOLE ACETIC ACIDs).Pp ARF4 could bind the promoters of lateral root development gene Pp LBD16 and auxin transport gene Pp PIN1 to activate their transcription.Ectopic overexpression of Pp ARF4 and Pp LBD16 in Arabidopsis promoted AR development.Additionally,Pp ARF4 could act as a negative regulator of flavone synthesis and thus prevent the explants from browning.The results not only provide novel insights into the functions of ARFs in regulating plant growth and development,but will also be useful for fulfilling asexual propagation by stem cuttings in peach.

FY-4 A/GIIRS反演夏冬季有云时大气温湿度廓线的精度评估

FY-4A/GIIRS(Geostationary Interferometric Infrared Sounder)首次实现了地球静止轨道红外高光谱探测,可以连续获得高垂直分辨率的大气温度和湿度廓线信息。当GIIRS视场内有云存在时,目前Level 2业务大气温湿度垂直廓线产品只提供观测视场内云顶以上高度的温度廓线,且不反演整个视场的湿度廓线。基于GIIRS辐射观测值用U-Net卷积神经网络算法实现了全天空大气温湿度廓线反演,包括晴空和全云覆盖视场,同时利用常规无线电探空观测资料对反演精度进行了检验。结果表明:U-Net算法有云视场的温湿度廓线反演能力与晴空相当,且夏季温度反演精度优于冬季,有利于灾害性天气多发季节的监测。在云系较活跃的夏季,随着视场内云量的增加温度廓线反演精度逐渐变高,表明该算法适用于有云时大气温度廓线反演,而湿度随着云量的增加反演均方根误差RMSE增大。视场内不同云光学厚度时温度反演误差相差不大,RMSE均在2.5 K左右,平均偏差ME在1 K以内,对流层高层薄云时反演误差相对而言较小。湿度反演随着云光学厚度的增大反演误差也增大,说明对于一定程度的薄云,GIIRS能够获得不错的反演精度。虽然U-Net算法物理意义不明确,但是能够快速实现全天空大气温湿度廓线反演,尤其在有云时能够获得更高的反演精度。

The interplay mechanism between IDH mutation, MGMT-promoter methylation, and PRMT5 activity in the progression of grade 4 astrocytoma: unraveling the complex triad theory

Background:The dysregulation of Isocitrate dehydrogenase(IDH)and the subsequent production of 2-Hydroxyglutrate(2HG)may alter the expression of epigenetic proteins in Grade 4 astrocytoma.The interplay mechanism between IDH,O-6-methylguanine-DNA methyltransferase(MGMT)-promoter methylation,and protein methyltransferase proteins-5(PRMT5)activity,with tumor progression has never been described.Methods:A retrospective cohort of 34 patients with G4 astrocytoma is classified into IDH-mutant and IDH-wildtype tumors.Both groups were tested for MGMT-promoter methylation and PRMT5 through methylation-specific and gene expression PCR analysis.Inter-cohort statistical significance was evaluated.Results:Both IDH-mutant WHO grade 4 astrocytomas(n=22,64.7%)and IDH-wildtype glioblastomas(n=12,35.3%)had upregulated PRMT5 gene expression except in one case.Out of the 22 IDH-mutant tumors,10(45.5%)tumors showed MGMT-promoter methylation and 12(54.5%)tumors had unmethylated MGMT.All IDH-wildtype tumors had unmethylated MGMT.There was a statistically significant relationship between MGMT-promoter methylation and IDH in G4 astrocytoma(p-value=0.006).Statistically significant differences in progression-free survival(PFS)were also observed among all G4 astrocytomas that expressed PRMT5 and received either temozolomide(TMZ)or TMZ plus other chemotherapies,regardless of their IDH or MGMT-methylation status(p-value=0.0014).Specifically,IDH-mutant tumors that had upregulated PRMT5 activity and MGMT-promoter methylation,who received only TMZ,have exhibited longer PFS.Conclusions:The relationship between PRMT5,MGMT-promoter,and IDH is not tridirectional.However,accumulation of D2-hydroxyglutarate(2-HG),which partially activates 2-OG-dependent deoxygenase,may not affect their activities.In IDH-wildtype glioblastomas,the 2HG-2OG pathway is typically inactive,leading to PRMT5 upregulation.TMZ alone,compared to TMZ-plus,can increase PFS in upregulated PRMT5 tumors.Thus,using a PRMT5 inhibitor in G4 astrocytomas may help in tumor regression.

Anti-aquaporin-4 antibody(AQP4-IgG)and anti-myelin oligodendrocyte glycoprotein antibody(MOG-IgG)in the cerebrospinal fluid

In the last decade,a new neurological disease concept known as anti-myelin oligodendrocyte glycoprotein antibody(MOG-IgG)-associated disease(MOGAD)has emerged and is currently one of the most focused research areas in the field of neuroimmunology.MOG is a membrane protein mainly expressed on the surface of oligodendrocytes(Zhou et al.,2006).The exact pathogenic role of MOG-IgG in patients with MOGAD remains unclear;however,MOG-IgG has been suggested to cause tissue alterations and damage MOG-expressing cells(Zhou et al.,2006).The pathogenicity of MOG-IgG is further supported by the observation that only a few patients with acquired central nervous system(CNS)demyelinating syndromes exhibit both anti-aquaporin-4 antibody(AQP4-IgG)and MOG-IgG simultaneously,particularly with clear positivity levels of these antibodies as indicated by a cell-based assay result with a titer≥1:100(Sechi et al.,2021;Banwell et al.,2023).

Chemokine platelet factor 4 accelerates peripheral nerve regeneration by regulating Schwann cell activation and axon elongation

Schwann cells in peripheral nerves react to traumatic nerve injury by attempting to grow and regenerate.Howeve r,it is unclear what factors play a role in this process.In this study,we searched a GEO database and found that expression of platelet factor 4 was markedly up-regulated after sciatic nerve injury.Platelet factor is an important molecule in cell apoptosis,diffe rentiation,survival,and proliferation.Further,polymerase chain reaction and immunohistochemical staining confirmed the change in platelet factor 4 in the sciatic nerve at different time points after injury.Enzyme-linked immunosorbent assay confirmed that platelet factor 4 was secreted by Schwann cells.We also found that silencing platelet factor 4 decreased the proliferation and migration of primary cultured Schwann cells,while exogenously applied platelet factor 4 stimulated Schwann cell prolife ration and migration and neuronal axon growth.Furthermore,knocking out platelet factor 4 inhibited the prolife ration of Schwann cells in injured rat sciatic nerve.These findings suggest that Schwann cell-secreted platelet factor 4 may facilitate peripheral nerve repair and regeneration by regulating Schwann cell activation and axon growth.Thus,platelet factor 4 may be a potential therapeutic target for traumatic peripheral nerve injury.

Lactiplantibacillus plantarum FRT4 attenuates high-energy low-protein dietinduced fatty liver hemorrhage syndrome in laying hens through regulating gut-liver axis

Background Fatty liver hemorrhage syndrome(FLHS)becomes one of the most major factors resulting in the laying hen death for caged egg production.This study aimed to investigate the therapeutic effects of Lactiplantibacillus plan-tarum(Lp.plantarum)FRT4 on FLHS model in laying hen with a focus on liver lipid metabolism,and gut microbiota.Results The FLHS model of laying hens was established by feeding a high-energy low-protein(HELP)diet,and the treatment groups were fed a HELP diet supplemented with differential proportions of Lp.plantarum FRT4.The results indicated that Lp.plantarum FRT4 increased laying rate,and reduced the liver lipid accumulation by regulating lipid metabolism(lipid synthesis and transport)and improving the gut microbiota composition.Moreover,Lp.plan-tarum FRT4 regulated the liver glycerophospholipid metabolism.Meanwhile,“gut-liver”axis analysis showed that there was a correlation between gut microbiota and lipid metabolites.Conclusions The results indicated that Lp.plantarum FRT4 improved the laying performance and alleviated FLHS in HELP diet-induced laying hens through regulating“gut-liver”axis.Our findings reveal that glycerophospholipid metabolism could be the underlying mechanism for the anti-FLHS effect of Lp.plantarum FRT4 and for future use of Lp.plantarum FRT4 as an excellent additive for the prevention and mitigation of FLHS in laying hens.

Cloning of sft-4 and its influence on vitality and virulence of pine wood nematode,Bursaphelenchus xylophilus

In our previous screening of the transcriptome of the causal agent of the devastating pine wilt disease,pine wood nematode(PWN,Bursaphelenchus xylophilus),after treatment with the nematicide fomepizole,Surfeit locus gene sft-4,which encodes a regulatory factor,was found to be downregulated.In situ hybridization results showed that the sft-4 was continuously expressed from egg to adult and was especially high in the reproductive system.Here in a study of the effect of RNA interference(RNAi)of sft-4 and recombinant SFT-4 on PWN activity,treatment with sft-4 dsRNA inhibited feeding,reproduction,oviposition and egg hatching of PWN with the greatest inhibition on reproduction and oviposition,whereas recombinant SFT-4 had the opposite effect.In addition,RNAi of sft-4 changed the female–male ratio and lifespan of PWN.In bioassays of PWNs,with RNAi of sft-4 on seedlings and 2-year-old Pinus thunbergii trees,none of the treated plants developed symp-toms during the monitoring period,indicating that virulence of PWNs was either significantly weakened.These results indicate that the influence of sft-4 on PWN pathogenicity may be mainly through regulating reproductive function of PWN and its lifespan.

Quantitative trait loci identification reveals zinc finger protein CONSTANS-LIKE 4 as the key candidate gene of stigma color in watermelon(Citrullus lanatus)

Stigma color is a critical agronomic trait in watermelon that plays an important role in pollination.However,there are few reports on the regulation of stigma color in watermelon.In this study,a genetic analysis of the F2 population derived from ZXG1553(P1,with orange stigma)and W1-17(P2,with yellow stigma)indicated that stigma color is a quantitative trait and the orange stigma is recessive compared with the yellow stigma.Bulk segregant analysis sequencing(BSA-seq)revealed a 3.75 Mb segment on chromosome 6 that is related to stigma color.Also,a major stable effective QTL Clqsc6.1(QTL stigma color)was detected in two years between cleaved amplified polymorphic sequencing(CAPS)markers Chr06_8338913 and Chr06_9344593 spanning a~1.01 Mb interval that harbors 51 annotated genes.Cla97C06G117020(annotated as zinc finger protein CONSTANS-LIKE 4)was identified as the best candidate gene for the stigma color trait through RNA-seq,quantitative real-time PCR(qRT-PCR),and gene structure alignment analysis among the natural watermelon panel.The expression level of Cla97C06G117020 in the orange stigma accession was lower than in the yellow stigma accessions with a significant difference.A nonsynonymous SNP site of the Cla97C06G117020 coding region that causes amino acid variation was related to the stigma color variation among nine watermelon accessions according to their re-sequencing data.Stigma color formation is often related to carotenoids,and we also found that the expression trend of ClCHYB(annotated asβ-carotene hydroxylase)in the carotenoid metabolic pathway was consistent with Cla97C06G117020,and it was expressed in low amounts in the orange stigma accession.These data indicated that Cla97C06G117020 and ClCHYB may interact to form the stigma color.This study provides a theoretical basis for gene fine mapping and mechanisms for the regulation of stigma color in watermelon.

Circ_0012152 Accelerates Acute Myeloid Leukemia Progression through the miR-652-3p/SOX4 Axis

Objective Acute myeloid leukemia(AML)is an aggressive hematological malignancy characterized by abnormal myeloid blast expansion.Recent studies have demonstrated that circular RNAs play a role in AML pathogenesis.In this study,we aimed to investigate the clinical significance of circ_0012152 in AML and elucidate its underlying molecular mechanism in the pathogenesis of this condition.Methods Circ_0012152 expression was detected by quantitative real-time polymerase chain reaction in samples obtained from 247 patients with AML and 40 healthy controls.A systematic analysis of clinical characteristics and prognostic factors was also conducted.Cell growth was assessed using the Cell Counting Kit-8(CCK-8)assay,and apoptosis and cell cycle progression were evaluated by flow cytometry.Moreover,RNA pull-down was performed to identify target microRNAs,and transcriptome RNA sequencing and bioinformatics analyses were utilized to identify downstream mRNA targets.Results Circ_0012152 was significantly upregulated in samples from patients with AML and served as an independent adverse prognostic factor for overall survival(OS)(hazard ratio:2.357;95%confidence interval 1.258–4.415).The circ_0012152 knockdown reduced cell growth,increased apoptosis,and inhibited cell cycle progression in AML cell lines.RNA pull-down and sequencing identified miR-652-3p as a target microRNA of circ_0012152.Cell growth inhibition by circ_0012152 knockdown was significantly relieved by miR-652-3p inhibitors.We suggested that miR-652-3p targeted SOX4,as the decrease in SOX4 expression resulting from circ_0012152 knockdown was upregulated by miR-652-3p inhibitors in AML cells.Conclusion Circ_0012152 is an independent poor prognostic factor for OS in AML,and it promotes AML cell growth by upregulating SOX4 through miR-652-3p.

Pulmonary Edema and Pleural Effusion Detection Using Efficient Net-V1-B4 Architecture and AdamW Optimizer from Chest X-Rays Images

This paper presents a novelmulticlass systemdesigned to detect pleural effusion and pulmonary edema on chest Xray images,addressing the critical need for early detection in healthcare.A new comprehensive dataset was formed by combining 28,309 samples from the ChestX-ray14,PadChest,and CheXpert databases,with 10,287,6022,and 12,000 samples representing Pleural Effusion,Pulmonary Edema,and Normal cases,respectively.Consequently,the preprocessing step involves applying the Contrast Limited Adaptive Histogram Equalization(CLAHE)method to boost the local contrast of the X-ray samples,then resizing the images to 380×380 dimensions,followed by using the data augmentation technique.The classification task employs a deep learning model based on the EfficientNet-V1-B4 architecture and is trained using the AdamW optimizer.The proposed multiclass system achieved an accuracy(ACC)of 98.3%,recall of 98.3%,precision of 98.7%,and F1-score of 98.7%.Moreover,the robustness of the model was revealed by the Receiver Operating Characteristic(ROC)analysis,which demonstrated an Area Under the Curve(AUC)of 1.00 for edema and normal cases and 0.99 for effusion.The experimental results demonstrate the superiority of the proposedmulti-class system,which has the potential to assist clinicians in timely and accurate diagnosis,leading to improved patient outcomes.Notably,ablation-CAM visualization at the last convolutional layer portrayed further enhanced diagnostic capabilities with heat maps on X-ray images,which will aid clinicians in interpreting and localizing abnormalities more effectively.

Targeting CXCR4 and EDN1 for the treatment of recurrent miscarriage using stearic acid from traditional Chinese medicine

Background:Recurrent miscarriage(RM)affects an estimated 1-3%of couples attempting to conceive,and its molecular components stay ineffectively caught on.This study aims to explore potential therapeutic targets for RM by examining gene expression patterns and biological pathways in both mouse and human RM models.Meanwhile,explore relevant traditional Chinese medicine(TCM)components targeting potential therapeutic targets.Methods:We utilized the GSE211251 mouse and the GSE26787 human datasets,employing gene set enrichment analysis and gene metaphysics analysis to examine differentially expressed genes and enriched pathways.Single-cell RNA analysis uncovered cellular heterogeneity and arranged pharmacology-mapped potential drug-target intelligence.We employed molecular docking strategies to assess the affinity of TCM components for key proteins.Results:In the mouse model,genes such as Ly6f1 and Gpr26 were upregulated,while Stc5a and Galca exhibited downregulation.Gene set enrichment analysis identified key pathways,including the tumor necrosis factor-mediated signaling pathway.In human samples,Gene Ontology analysis highlighted processes such as apoptosis and cell adhesion.Single-cell RNA analysis revealed distinct cellular populations between normal and RM samples.Systems pharmacology identified C-X-C motif chemokine receptor 4(CXCR4)and endothelin 1(EDN1)as potential key targets,and molecular docking confirmed that stearic acid from TCM appears to regulate these proteins.Conclusion:This study presents a comprehensive analysis of the genetic and cellular underpinnings of RM,identifying CXCR4 and EDN1 as promising therapeutic targets.Stearic acid from TCM could provide targeted treatment by modulating these key proteins,paving the way for new RM treatment strategies.

Effect of pre-deformation on aging creep of Al-Li-S4 alloy and its constitutive modeling

A set of uniaxial tensile creep tests at different pre-deformations, aging temperatures and stress levels were carried out for Al-Li-S4 alloy, and the creep behavior and the effects of pre-deformation on mechanical properties and microstructures were determined under basic thermodynamics conditions of aging forming. The results show that pre-deformation shortens the time of primary creep and raises the second steady-state creep rate. Then, the total creep strain is greater, but in the range of test parameters it is still smaller than that without pre-deformation. In addition, transmission electron microscopy（TEM） observation shows that pre-deformation promotes the formation of T1 phase and θ′ phase and makes them distribute more dispersively, while inhibits the generation of δ′ phase, which leads to the improvement of mechanical properties of the alloy. A unified constitutive model reflecting the effects of aging mechanism, stress levels and different pre-deformations was established. The fitting results agree with the experimental data well.

Use of the “Veda-Lab Easy Reader+” for the Determination of T3, T4 and TSH Hormones in the Mountainous Population of Benin: Case of Natitingou

The thyroid, an endocrine gland located at the base of the neck, produces thyroid hormones (triiodothyronine (T3) and thyroxine (T4)). The production of these hormones is possible by iodine and other nutrients such as selenium and certain vitamins. To assess the thyroid disturbances in the mountain population of Benin, a survey was conducted in Natitingou, a mountain town located in the department of Atacora, in the northwest of Benin, on a sample of thirty (30) adults (15 men and 15 women), most of whom are educated. The results of the questionnaire revealed that 43% of the surveyed population acknowledged having knowledge on the mentioned subject and have dietary habits based on the consumption of seafood, and also legumes (20%). The examination of the serum results of the dosage of T3, T4 and TSH hormones revealed cases of thyroid disturbances in the region (36.32% in men and 44.98% in women). The analysis of a comparative table including the “VEDALAB Easy Reader+” and five (05) other readers, presents the performance, reading techniques, principles, advantages and disadvantages of each device. Pending further studies, some recommendations were made at the end of this study to the academic authorities regarding probable cases of dysthyroidism for which additional examinations are required and an awareness for the improvement of dietary habits.

Effect of electrochemical state on corrosion-wear behaviors of TC4 alloy in artificial seawater

The electrochemical and corrosion?wear behaviors of TC4 alloy in artificial seawater were studied. And the influences of electrochemical state on passive behavior, failure mechanism of passive film and corrosion?wear synergy were emphatically analyzed. The corrosion?wear analysis of the alloy was fulfilled by methods of mass loss, electrochemical testing and scanning electron microscope (SEM). It can be observed that the cathodic shift of open circuit potential and three order of magnitude increase of current density can be obtained during corrosion?wear process. Total corrosion?wear loss increases with increasing applied potential, confirming the synergy between wear and corrosion. High polarisation potential results in low coefficient of friction and high corrosion rate. The relative contribution of pure mechanical wear to total material loss deceases obviously with the increase of potential from open circuit potential to 0.9 V during corrosion?wear. Contributions of wear-induced-corrosion and corrosion-induced-wear are significant especially at higher potentials.

A systematic evaluation of the performance of GPT-4 and PaLM2 to diagnose comorbidities in MIMIC-IV patients

Background:Given the strikingly high diagnostic error rate in hospitals,and the recent development of Large Language Models(LLMs),we set out to measure the diagnostic sensitivity of two popular LLMs:GPT-4 and PaLM2.Small-scale studies to evaluate the diagnostic ability of LLMs have shown promising results,with GPT-4 demonstrating high accuracy in diagnosing test cases.However,larger evaluations on real electronic patient data are needed to provide more reliable estimates.Methods:To fill this gap in the literature,we used a deidentified Electronic Health Record(EHR)data set of about 300,000 patients admitted to the Beth Israel Deaconess Medical Center in Boston.This data set contained blood,imaging,microbiology and vital sign information as well as the patients'medical diagnostic codes.Based on the available EHR data,doctors curated a set of diagnoses for each patient,which we will refer to as ground truth diagnoses.We then designed carefully-written prompts to get patient diagnostic predictions from the LLMs and compared this to the ground truth diagnoses in a random sample of 1000 patients.Results:Based on the proportion of correctly predicted ground truth diagnoses,we estimated the diagnostic hit rate of GPT-4 to be 93.9%.PaLM2 achieved 84.7%on the same data set.On these 1000 randomly selected EHRs,GPT-4 correctly identified 1116 unique diagnoses.Conclusion:The results suggest that artificial intelligence(AI)has the potential when working alongside clinicians to reduce cognitive errors which lead to hundreds of thousands of misdiagnoses every year.However,human oversight of AI remains essential:LLMs cannot replace clinicians,especially when it comes to human understanding and empathy.Furthermore,a significant number of challenges in incorporating AI into health care exist,including ethical,liability and regulatory barriers.

Research on the Agronomic,Quality Traits and the Corresponding Background Genes Distribution of Wheat Germplasm Ningchun 4 and Its Parents

[Objective] The aim of this study was to observe the agronomic,yield and quality traits of Ningchun 4 and its parents under the same environmental conditions,as well as to carry out molecular detection on the background genes distribution of the corresponding traits.[Method]Ningchun 4 and its parents Sonora 64,Hongtu,Abbondanza,Quality were used as materials to detect the agronomic and quality traits,as well as to analyze the genetic variation laws by molecular determination method.[Result]Ningchun 4 had inherited the advantages of bigger spike,red and hard grain from Sonora 64 and higher 1 000-grain weight from Hongtu.However,it had also inherited the disadvantages of late-maturing from Sonora 64 and lower tillering ability from Hongtu;the grain quality of Ningchun 4 was slightly lower than the Sonora 64;Ningchun 4 had high quality subunit of 5＋10,which had good dough rheological properties.[Conclusion]Ningchun 4 had inherited the long photoperiod characteristics and no-resistant to slow-leaf rusting and stripe rust characteristics from Hongtu and low PPO activity,high yellow pigments content from parents.

The Initial Reactions of HaPO4 and NaH2PO4 Supported on Silica： A Joint Experimental and Theoretical Study

A combination of X-ray powder diffraction, thermogravimetric analysis, diffuse reflection infrared Fourier transform, and ^31p magic-angle spinning nuclear magnetic resonance techniques with density function computation was used to elucidate the products and mecha- nism of the reactions among silica, H3PO4, and NaH2PO4 during the preparation of silica supported H3PO4 and NaH2PO4 catalysts. The spectral test results indicate that besides polyphosphoric acid, silicon phosphates on silica supported H3PO4 are also formed. On silica supported NaH2PO4 only sodium polyphosphates are present. Density functional theory （DFT） simulations indicate that in the initial stage, reaction of H3PO4 with silanol groups on the silica support is more favorable than that between H3PO4 itself. In contrast, dimerization and trimerization of NaH2PO4 are predicted to be the predominant initial reactions for the silica supported NaH2PO4 catalyst.

MPEG-4 AAC解码器在TMS320C6416上的实现

结合定点DSP芯片TMS320C6416,给出了MPEG-4AAC(LC)音频解码器在其测试评估平台(TEB)上的实现方案,并从多方面对AAC(LC)解码器进行了优化设计。实验结果表明,在确保音频解码质量的同时,算法的运行速度和存储器占用情况都有了较大的改善,为视频及其它应用留下了充足的处理空间。

粤西北煤矸石制备4 A。沸石分子筛的工艺实验研究

粤西北煤矸石制备４Ａ。沸石分子筛的工艺实验研究曹俊臣彭金莲冉红彦李本超（中国科学院广州地球化学研究所，广州５１０６４０）关键词煤矸石４Ａ。沸石分子筛工艺实验粤西北采用煤矸石合成４Ａ。分子筛，既可清除污染，又能变废为宝。我们以广东粤西北煤矸石为原料，初...