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Background Circulating tumor DNA (ctDNA) enables rapid and repeat testing of actionable mutations with fewer side effects compared to tissue biopsy. And the use of next-generation sequencing (NGS) based on ctDNA as a diagnostic tool in clinical settings is growing. We developed a hybridization capture massively parallel NGS assay using ctDNA, USCI-CT, across 20 cancer relevant genes of non-small cell lung cancer (NSCLC). Clinical validations of this assay across 17 mutations were presented.Methods Clinical NSCLC samples and simulated negative and positive cell-free DNA (cfDNA) samples were applied to validate the technical performance of this assay. First, 40 simulated negative control cfDNA samples were used to evaluate the systemic error levels to delimit the limit of detection of variant allele frequency (VAF). And, 92 clinical NSCLC samples were genotyped by USCI-CT and ddPCR to decide the proper limit of VAF, depth of coverage, and the average depth of target regions for confidently detecting mutations for USCI-CT. Second, one simulated negative cfDNA sample and two simulated positive cfDNA samples in seven replicates were used to assess the precision of the assay. Finally, 518 clinical NSCLC samples were recruited to evaluate the analytical sensitivity and specificity of USCI-CT.Results The assay-specific systemic error rate was below 0.20% by sequencing sixty-seven simulated negative control cfDNA samples. The proper cutoff of detection of VAF, coverage of depth of mutation loci, and average depth of target regions were decided at 0.20%, 1000×, and 1400×. The analytical sensitivity and specificity achieved a satisfactory level with 98.32% and 99.85% for single nucleotide variant (SNV) detection and 97.30% and 96.86% for EGFR exon 19 deletions, respectively.Conclusions The results indicated that the USCI-CT assay can reliably detect NSCLC related mutations at 0.20% variant frequency level and provided insights into the incorporation of hybridization captured NGS-based ctDNA assay into oncology clinical settings.

Gastric cancer (GC) is usually diagnosed in an advanced stage at the first visit due to the atypical clinical symptoms. The low surgical resection rate and chemotherapy sensitivity result in dismal survival. Therefore, it is urgent to develop novel biomarkers with high sensitivity and specificity to accurately assess the prognosis of GC patients. In the present study, 3385 differentially expressed genes (DEGs) were obtained from the single-cell RNA sequencing data of GC specimens. Using the unsupervised dimensionality reduction, we further found 3 subsets of cells including gastric cells, plasmacytoid dendritic cells, and memory T cells. Based on the cell clustering, we explored the key regulatory genes for GC progression by pseudo-time analysis and functional enrichment analysis. According to the results, the significant differentially expressed fatty acid-binding protein 1 (FABP1) verified by pseudo-time analysis was identified as the hub gene of GC progression. FABP1 was shown to be closely related to the long-term survival and the age at diagnosis of patients with GC in analysis based on the TCGA (The Cancer Genome Atlas) database. To further verify the role of FABP1 in GC, we performed immunohistochemical (IHC) analysis using the GC tissue microarray and found that the expression level of FABP1 was higher in GC tissues than in the adjacent tissues. Moreover, GC patients with higher expression of FABP1 had a worse clinical outcome. In summary, our study revealed that FABP1 is a potential effective biomarker for the prognosis of GC, and high expression of FABP1 predicts unsatisfactory survival.

BACKGROUND: Acute liver injury can occur at any stage of sepsis and is an important sign of multiple organ dysfunction syndrome (MODS). Studies have shown that agmatine (AGM) can effectively improve liver injury caused by sepsis. However, due to the numerous metabolites and metabolic pathways of AGM in the human body, its mechanism in treating septic liver injury is unclear. METHODS: In this study, a liver injury model of septic Sprague-Dawley rats was established by cecal ligation and perforation (CLP). After AGM treatment, transcriptomics combined with metabolomics was employed to analyze the gene expression levels and metabolite changes. RESULTS: The results showed that AGM decreased the expression levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), procalcitonin (PCT), and inflammatory factors [interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β)] in the serum of septic rats. It also reduced liver inflammatory cell infiltration and abnormal lipid metabolism, and promoted the survival rate of septic rats. In addition, 17 differentially-expressed genes were identified by transcriptomics, mainly in arginine and proline metabolism, the arachidonic acid metabolism pathway, as well as the nuclear factor kappa B (NF-κB) and AMP-activated protein kinase (AMPK)-peroxisome proliferator-activated receptor α (PPARα) signal transduction pathways. Metabolomics analysis was carried out to study the potential liver metabolism spectrum changes induced by AGM treatment. The results showed significant changes in 26 metabolites in the rat liver samples, mainly involved in arginine and proline metabolism, arachidonic acid metabolism, linoleic acid metabolism, and fatty acid metabolism. CONCLUSIONS: The integrated transcriptomics and metabolomics analysis demonstrated that AGM improved septic liver injury by regulating lipid metabolism, and reduced the inflammatory reaction by affecting fatty acid metabolism, amino acid metabolism, and the arachidonic acid metabolism pathway. The integration of transcriptomics and metabolomics provides an effective means to elucidate AGM’s therapeutic pathways and biomarkers.

Many studies have examined the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants on neutralizing antibody activity after they have become dominant strains. Here, we evaluate the consequences of further viral evolution. We demonstrate mechanisms through which the SARS-CoV-2 receptor binding domain (RBD) can tolerate large numbers of simultaneous antibody escape mutations and show that pseudotypes containing up to seven mutations, as opposed to the one to three found in previously studied variants of concern, are more resistant to neutralization by therapeutic antibodies and serum from vaccine recipients. We identify an antibody that binds the RBD core to neutralize pseudotypes for all tested variants but show that the RBD can acquire an N-linked glycan to escape neutralization. Our findings portend continued emergence of escape variants as SARS-CoV-2 adapts to humans.

Respiratory syncytial virus (RSV) and human metapneumovirus (HMPV) cause severe respiratory diseases in infants and elderly adults1. No vaccine or effective antiviral therapy currently exists to control RSV or HMPV infections. During viral genome replication and transcription, the tetrameric phosphoprotein P serves as a crucial adaptor between the ribonucleoprotein template and the L protein, which has RNA-dependent RNA polymerase (RdRp), GDP polyribonucleotidyltransferase and cap-specific methyltransferase activities2,3. How P interacts with L and mediates the association with the free form of N and with the ribonucleoprotein is not clear for HMPV or other major human pathogens, including the viruses that cause measles, Ebola and rabies. Here we report a cryo-electron microscopy reconstruction that shows the ring-shaped structure of the polymerase and capping domains of HMPV-L bound to a tetramer of P. The connector and methyltransferase domains of L are mobile with respect to the core. The putative priming loop that is important for the initiation of RNA synthesis is fully retracted, which leaves space in the active-site cavity for RNA elongation. P interacts extensively with the N-terminal region of L, burying more than 4,016 A2 of the molecular surface area in the interface. Two of the four helices that form the coiled-coil tetramerization domain of P, and long C-terminal extensions projecting from these two helices, wrap around the L protein in a manner similar to tentacles. The structural versatility of the four P protomers—which are largely disordered in their free state—demonstrates an example of a ‘folding-upon-partner-binding’ mechanism for carrying out P adaptor functions. The structure shows that P has the potential to modulate multiple functions of L and these results should accelerate the design of specific antiviral drugs. A cryo-electron microscopy reconstruction shows the ring-shaped structure of the polymerase and capping domains of the L protein bound to a tetramer of phosphoprotein P of the human metapneumovirus.

The SARS-CoV-2 viral spike (S) protein mediates attachment and entry into host cells and is a major target of vaccine and drug design. Potent SARS-CoV-2 neutralizing antibodies derived from closely related antibody heavy chain genes (IGHV3-53 or 3-66) have been isolated from multiple COVID-19 convalescent individuals. These usually contain minimal somatic mutations and bind the S receptor-binding domain (RBD) to interfere with attachment to the cellular receptor angiotensin-converting enzyme 2 (ACE2). We used antigen-specific single B cell sorting to isolate S-reactive monoclonal antibodies from the blood of a COVID-19 convalescent individual. The seven most potent neutralizing antibodies were somatic variants of the same IGHV3-53-derived antibody and bind the RBD with varying affinity. We report X-ray crystal structures of four Fab variants bound to the RBD and use the structures to explain the basis for changes in RBD affinity. We show that a germline revertant antibody binds tightly to the SARS-CoV-2 RBD and neutralizes virus, and that gains in affinity for the RBD do not necessarily correlate with increased neutralization potency, suggesting that somatic mutation is not required to exert robust antiviral effect. Our studies clarify the molecular basis for a heavily germline-biased human antibody response to SARS-CoV-2.

Structure-based vaccine design depends on extensive structural analyses of antigen-antibody complexes.Single-particle electron cryomicroscopy (cryoEM) can circumvent some of the problems of x-ray crystallography as a pipeline for obtaining the required structures. We have examined the potential of single-particle cryoEM for determining the structure of influenza-virus hemagglutinin (HA):single-chain variable-domain fragment complexes, by studying a complex we failed to crystallize in pursuing an extended project on the human immune response to influenza vaccines.The result shows that a combination of cryoEM and molecular modeling can yield details of the antigen-antibody interface, although small variation in the twist of the rod-likeHA trimer limited the overall resolution to about 4.5Å.Comparison of principal 3D classes suggests ways to modify the HA trimer to overcome this limitation. A closely related antibody from the same donor did yield crystals when bound with the same HA, giving us an independent validation of the cryoEM results.The two structures also augment our understanding of receptor-binding site recognition by antibodies that neutralize a wide range of influenza-virus variants.

The HIV-1 envelope protein (Env) is the target of neutralizing antibodies and the template for vaccine immunogen design. The dynamic conformational equilibrium of trimeric Env influences its antigenicity and potential immunogenicity. Antibodies that bind at the trimer apex stabilize a “closed” conformation characteristic of the most difficult to neutralize isolates. A goal of vaccine development is therefore to mimic the closed conformation in a designed immunogen. A disulfide-stabilized, trimeric Env ectodomain -- the “SOSIP” construct -- has many of the relevant properties; it is also particularly suitable for structure determination. Some single-molecule studies have, however, suggested that the SOSIP trimer is not a good representation of Env on the surface of a virion or an infected cell. We isolated Env (fully cleaved to gp120 and gp41) from the surface of expressing cells using tagged, apex-binding Fab PG16 and determined the structure of the PG16-Env complex by cryo-EM to an overall resolution of 4.6 Å. Placing the only purification tag on the Fab ensured that the isolated Env was continuously stabilized in its closed, native conformation. The Env structure in this complex corresponds closely to the SOSIP structures determined by both x-ray crystallography and cryo-EM. Although the membrane-interacting elements are not resolved in our reconstruction, we can make inferences about the connection between ectodomain and membrane-proximal external region (MPER) by reference to the published cryo-tomography structure of an Env “spike” and the NMR structure of the MPER-transmembrane segment. We discuss these results in view of the conflicting interpretations in the literature.

Many individuals mount nearly identical antibody responses to SARS-CoV-2. To gain insight into how the viral spike (S) protein receptor-binding domain (RBD) might evolve in response to common antibody responses, we studied mutations occurring during virus evolution in a persistently infected immunocompromised individual. We use antibody Fab/RBD structures to predict, and pseudotypes to confirm, that mutations found in late-stage evolved S variants confer resistance to a common class of SARS-CoV-2 neutralizing antibodies we isolated from a healthy COVID-19 convalescent donor. Resistance extends to the polyclonal serum immunoglobulins of four out of four healthy convalescent donors we tested and to monoclonal antibodies in clinical use. We further show that affinity maturation is unimportant for wildtype virus neutralization but is critical to neutralization breadth. As the mutations we studied foreshadowed emerging variants that are now circulating across the globe, our results have implications to the long-term efficacy of S-directed countermeasures., Structural and functional analysis of the evolution of SARS-CoV-2 in a persistently infected immunocompromised individual yields insights into mutations that foreshadow emerging viral variants worldwide.

The HIV-1 envelope spike [Env; trimeric (gp160) 3 cleaved to (gp120/gp41) 3 ] induces membrane fusion, leading to viral entry. It is also the viral component targeted by neutralizing antibodies. Vaccine development requires production, in quantities suitable for clinical studies, of a recombinant form that resembles functional Env. HIV-1 gp140 trimers—the uncleaved ectodomains of (gp160) 3 —from a few selected viral isolates adopt a compact conformation with many antigenic properties of native Env spikes. One is currently being evaluated in a clinical trial. We report here low-resolution (20 Å) electron cryomicroscopy (cryoEM) structures of this gp140 trimer, which adopts two principal conformations, one closed and the other slightly open. The former is indistinguishable at this resolution from those adopted by a stabilized, cleaved trimer (SOSIP) or by a membrane-bound Env trimer with a truncated cytoplasmic tail (EnvΔCT). The latter conformation is closer to a partially open Env trimer than to the fully open conformation induced by CD4. These results show that a stable, uncleaved HIV-1 gp140 trimer has a compact structure close to that of native Env. IMPORTANCE Development of any HIV vaccine with a protein component (for either priming or boosting) requires production of a recombinant form to mimic the trimeric, functional HIV-1 envelope spike in quantities suitable for clinical studies. Our understanding of the envelope structure has depended in part on a cleaved, soluble trimer, known as SOSIP.664, stabilized by several modifications, including an engineered disulfide. This construct, which is difficult to produce in large quantities, has yet to induce better antibody responses than those to other envelope-based immunogens, even in animal models. The uncleaved ectodomain of the envelope protein, called gp140, has also been made as a soluble form to mimic the native Env present on the virion surface. Most HIV-1 gp140 preparations are not stable, however, and have an inhomogeneous conformation. The results presented here show that gp140 preparations from suitable isolates can adopt a compact, native-like structure, supporting its use as a vaccine candidate.

To the problem of many recently proposed RFID authentication protocol was soon find security holes, we analyzed the main reason, which is that protocol design is not rigorous, and the correctness of the protocol cannot be guaranteed. To this end, authentication test method was adopted in the process of the formal analysis and strict proof to the proposed RFID protocol in this paper. Authentication Test is a new type of analysis and design method of security protocols based on Strand space model, and it can be used for most types of the security protocols. After analysis the security, the proposed protocol can meet the RFID security demand: information confidentiality, data integrity and identity authentication.

The Chinese compound Kaixin Jieyu Fang can be used to treat vascular depression; however, the underlying mechanism remains unclear. This study established a rat model of chronic cerebral ischemia-caused white matter damage by ligation of the bilateral common carotid arteries. Rats received daily intragastric administration of a suspension of Kaixin Jieyu Fang powder. After 3, 7 and 21 days of treatment, the degree of white matter damage in the cerebral ischemia rat model was alleviated, Bcl-2 protein and mRNA expression in brain tissue increased, and Bax protein and mRNA expression decreased. These results indicate that Kaixin Jieyu Fang can alleviate cerebral white matter damage, and the underlying mechanism is associated with regulation of Bcl-2/Bax protein and mRNA expression, which is one of possible mechanism behind the protective effect of Kaixin Jieyu Fang against vascular depression.

With the development of Internet and multimedia computer technology, the virtual classroom has adequate technical support. The application of virtual classroom changes the traditional mode of education, and makes a fundamental change in the teaching and learning methods. Virtual classroom can effectively overcome a lot of difficulties of practical teaching in schools. The interaction and interesting of the virtual classroom environment is essential. This article discusses the application of VPN technology in the virtual classroom, which can make a scholar on the Internet be added to discussions and learn in the virtual classroom of Campus.

Most dsRNA viruses have a genome-enclosing capsid that comprises 120 copies of a single coat protein (CP). These 120 CP subunits are arranged as asymmetrical dimers that surround the icosahedral fivefold axes, forming pentamers of dimers that are thought to be assembly intermediates. This scheme is violated, however, in recent structures of two dsRNA viruses, a fungal virus from family Partitiviridae and a rabbit virus from family Picobirnaviridae, both of which have 120 CP subunits organized as dimers of quasisymmetrical dimers. In this study, we report the CP backbone trace of a second fungal partitivirus, determined in this case by electron cryomicroscopy and homology modeling. This virus also exhibits quasisymmetrical CP dimers that are connected by prominent surface arches and stabilized by domain swapping between the two CP subunits. The CP fold is dominated by α-helices, although β-strands mediate several important contacts. A dimer-of-dimers assembly intermediate is again implicated. The disordered N-terminal tail of each CP subunit protrudes into the particle interior and likely interacts with the genome during packaging and/or transcription. These results broaden our understanding of conserved and variable aspects of partitivirus structure and reflect the growing use of electron cryomicroscopy for atomic modeling of protein folds.

For most dsRNA viruses, the genome-enclosing capsid comprises 120 copies of a single capsid protein (CP) organized into 60 icosahedrally equivalent dimers, generally identified as 2 nonsymmetricallyinteracting CP molecules with extensive lateral contacts. The crystal structure of a partitivirus, Penicillium stoloniferum virus F (PsV-F), reveals a different organization, in which the CP dimer is related by almost-perfect local 2-fold symmetry, forms prominent surface arches, and includes extensive structure swapping between the 2 subunits. An electron cryomicroscopy map of PsV-F shows that the disordered N terminus of each CP molecule interacts with the dsRNA genome and probably participates in its packaging or transcription. Intact PsV-F particles mediate semiconservative transcription, and transcripts are likely to exit through negatively charged channels at the icosahedral 5-fold axes. Other findings suggest that the PsV-F capsid is assembled from dimers of CP dimers, with an arrangement similar to flavivirus E glycoproteins.

Single-subunit polymerases are universally encoded in both cellular organisms and viruses. Their three-dimensional structures have the shape of a right-hand with the active site located in the palm region, which has a topology similar to that of the RNA recognition motif (RRM) found in many RNA-binding proteins. Considering that polymerases have well conserved structures, it was surprising that the RNA-dependent RNA polymerases from birnaviruses, a group of dsRNA viruses, have their catalytic motifs arranged in a permuted order in sequence. Here we report the 2.5 Å structure of a birnavirus VP1 in which the polymerase palm subdomain adopts a new active site topology that has not been previously observed in other polymerases. In addition, the polymerase motif C of VP1 has the sequence of -ADN-, a highly unusual feature for RNA-dependent polymerases. Through site-directed mutagenesis, we have shown that changing the VP1 motif C from -ADN- to -GDD- results in a mutant with an increased RNA synthesis activity. Our results indicate that the active site topology of VP1 may represent a newly developed branch in polymerase evolution, and that birnaviruses may have acquired the -ADN- mutation to control their growth rate.

We explore by design and implementation the applicability of J2EE (Java 2 Platform, Enterprise Edition) architecture in supporting wireless services as well as web-based services. This has been demonstrated by implementing a wireless prescription system, which provides wireless services to physicians, and web-based services to pharmacies and administrators. The goal of the wireless prescription system is to improve the efficiency of the healthcare system by reducing the overall time and cost used to create documents and retrieve information. We also present a performance evaluation of the implemented wireless prescription system using latency as the performance metric. In particular, we investigated the overheads associated with different components of the underlying J2EE architecture, which includes the Session Bean, Entity Bean, and the database. We found that the latency overheads introduced by these components account for 3.8-4.3%, 3.9-4.4%, and 91.8% of the total delay experienced inside the J2EE architecture respectively.

SummaryLow-dose images obtained by electron cryo-microscopy (cryo-EM) are often affected by blurring caused by sample motion during electron beam exposure, degrading signal especially at high resolution. We show here that we can align frames of movies, recorded with a direct electron detector during beam exposure of rotavirus double-layered particles, thereby greatly reducing image blurring caused by beam-induced motion and sample stage instabilities. This procedure increases the efficiency of cryo-EM imaging and enhances the resolution obtained in three-dimensional reconstructions of the particle. Using movies in this way is generally applicable to all cryo-EM samples and should also improve the performance of midrange electron microscopes that may have limited mechanical stability and beam coherence.

The Radio Frequency Identification (RFID) is an automatic identification system, which is widely used for industrial and individual applications. However, features of RFID systems present potential security and privacy problems. In an effort to resolve these problems and protect the users from tracing and also to support Low-cost RFID, in this paper, we propose an RFID security method that achieves all requirements based on a hash function and a symmetric key cryptosystem. In addition, our proposed method provides not only high-security but also high-efficiency.

The contrast observed in images of frozen-hydrated biological specimens prepared for electron cryo-microscopy falls significantly short of theoretical predictions. In addition to limits imposed by the current instrumentation, it is widely acknowledged that motion of the specimen during its exposure to the electron beam leads to significant blurring in the recorded images. We have studied the amount and direction of motion of virus particles suspended in thin vitrified ice layers across holes in perforated carbon films using exposure series. Our data show that the particle motion is correlated within patches of 0.3 – 0.5 μm, indicating that the whole ice layer is moving in a drum-like motion, with accompanying particle rotations of up to a few degrees. Support films with smaller holes, as well as lower electron dose rates tend to reduce beam-induced specimen motion, consistent with a mechanical effect. Finally, analysis of movies showing changes in the specimen during beam exposure show that the specimen moves significantly more at the start of an exposure than towards its end. We show how alignment and averaging of movie frames can be used to restore high-resolution detail in images affected by beam-induced motion.

Distribute hash table, abbr. as DHT, has provided a reliable and fast information exchange service in large scale P2P systems. There are two types of information indexing schemes in the implementation of real applications. One is that routing is separated from indexing, as in the case of eMule, and the other is that routing and indexing are combined together, as in the case of BitTorrent. This paper performs a comparative study of the information indexing scheme of DHT in eMule and BitTorrent. We have studied the relationship between the schemes and typical usage of the DHTs. Our major discovery is that the average number of index nodes for one single resource in the DHT of BitTorrent is one order of magnitude higher than that in the DHT of eMule. Furthermore, we have found that the main reason for such discrepancy is that, in BitTorrent application, the resource is related to a swarm, and a swarm tends to spread itself to more index nodes; Whereas in eMule, static index information such as keywords needs to be distributed among fewer index peers, so as to increase the high recall rate for users. In addition this paper also does a comparative study of the vulnerability of these two schemes with respect to certain security threats such as DDoS.

Password-based authenticated group key exchange (denoted by PGKE) provides n parties who hold a common human-memorable password for secure group communication. In this paper, applying the cryptographic technique to a password-authenticated 2-party key establishment protocol without random oracle assumption, a password-authenticated group key exchange under the help of a trusted server with CDH assumption is proposed. Comparing with other existing protocols, this protocol does not require any Server's public key and encryption of simple password (low-entropy).

The design principles of three familiar compensators are introduced. They are null lens compensator, offner compensator and reflective mirror compensator. Base on the three different theories, three different kinds of compensators for the testing of F/3 hyperbolic mirror are designed. The initial parameters of every compensator are analyzed in detail. The residual wavefront error, RMS radius of the spot diagrams and the tolerance of the three compensators are presented respectively. Due to the residual wavefront error consisted in these compensators themselves, higher order aspheric terms will be introduced into the hyperbolic mirror when using these compensators to test the mirror during the process of the fabrication. These higher order aspheric terms will influence the image quality of R-C system which primary mirror is this hyperbolic mirror. The simulation of this influence is analyzed in this paper. The residual wavefront error of the three final designs are all less than λ/30. The RMS radii of the spot diagrams are all less than 0.48μm.

In aspheric mirror polishing progress, the deformable polishing lap can change the lap surface to fit the surface of aspheric optical mirror. A novel method of designing deformable polishing lap is brought forward by using PZT actuator. It consists of an aluminum disk which can change surface profile continuously under the control of PZT actuators. When the deformable aspherical polishing lap moves on the surface of aspherical mirror, the needed deformation of each PZT actuator is calculated at any location. After each PZT actuator deforming, the surface profile of deformable aspherical polishing lap is changed to an off-axis surface of aspheric optical mirror at that location. In this paper, the rational of the PZT actuated deformable aspheric polishing lap is introduced,and the calculation method of deformation is explored also.By using finite element method, the deforming capability of the PZT actuated deformable aspheric polishing lap is simulated to reform a hyperboloid mirror with diameter 350mm,k=-1.112155,R=840.0 mm. Two type of PZT actuator arrangements are compared and analyzed. The results show that the PZT actuated deformable aspheric polishing lap can reshape to fit the surface of aspheric mirror and the RMS is less than 2um.

Aspheric surface can be thought as being enveloped by a series of spherical surfaces with their centre on the same axis but having different positions. These spherical surfaces are tangent with the aspheric surface. A Φ600 CNC aspheric grinding machine with this novel operating principleis manufactured. The machine was reported in August 2005. We choose δ p , e and α p as the key parameters of our grinding machine. δ p is the distance between the cup shaped tool's bottom and the vertex of the aspheric surface. α p is the rotational angle of the cup shaped tool. e is the space angle of the cup shaped tool during the fabrication process of convex aspheric surface. This grinding machine can be used to fabricate a conic concave aspheric surface continuously about three hours. But we need change the cup shaped tool one time when we fabricate a conic convex aspheric surface in also about three hours. The grinding machine can also be used to fabricate high-order aspheric surface. In the last report we intoroduced that we used this machined fabricating a RC telescope system's primary and the secondary mirror. The PV-value is less than 5μm for the primary Φ350 concave hyperbolic aspheric surface which departure is about 55μm. The residual errors can be removed easily. This machine have been improved both the cup shaped tool and filter system. Using this grinding machine we have fabricated another Φ460 concave aspheric surface during the last month. The PV-values of these two mirrors are both less than 7μm. The aspheric grinding machine can be fitted for fabricating concave conicoids.

Aspheric surface can be thought as being enveloped by a series of spherical surfaces with their centres on the same axis but having different positions. These spherical surfaces are tangent with the aspheric surface. We have manufactured a Φ600 CNC aspheric grinding machine with this novel operating principle. We choose δp , e and αp as the key parameters of our grinding machine. δp is the distance between the cup-shaped tools' bottom and the vertex of the aspheric surface. αp is the rotational angle of the cup-shaped tool. e is the space angle of the cup-shaped tool during the fabrication process of convex aspheric surface. Using this grinding machine, we can fabricate a conic concave aspheric surface continuously about three hours. But we need change the cup-shaped tool one time when we fabricate a conic convex aspheric surface in also about three hours. Our grinding machine can also be used to fabricate high-order aspheric surface. We used this machine fabricating a RC telescope system's primary and the secondary mirror. The PV-value is less than 5μm for the primary Φ350 concave hyperbolic aspheric surface which departure is about 55μm. We can polish and finish this aspheric surface with these residual errors easily. The manufacturing cost of the machine is about 300,000 RMB which is 1/10 of the LOH's product with the same maximum aperture of workpiece.

In wide linear-field of view, large relative aperture mirror system, it is unavoidable to use high order aspheric surfaces. In this paper the design of the compensators for testing the secondary and the tertiary mirror of a 3 mirror system is described. The surfaces under testing have high order up to r 16 . The diameter of the secondary is 112 mm, radius of curvature is 211.462 mm, and the conic constant is 0.07744075. The diameter of the tertiary is 272 mm, radius of curvature is 197.722 mm, and the conic constant is 0.2623604. Three elements and four elements compensators have been designed. The residual aspherical aberration has been minimized to about λ/20.

An ellipsoid mirror with Φ500 mm aperture has been successfully manufactured by NAIRC. The parameters of the mirror are as follows: diameter is Φ500 mm, radius of curvature is 1996 mm, conic constant k=-0.9545, requirements of surface accuracy are λ/10 (P-V) and λ/40 (RMS), (λ=632.8 nm). Based on the surface type, three kinds of test optics are designed. The errors of the elements in the testing optical path are analyzed. The small tools are used to figure the asphericity of the mirror. Finally surface accuracy of λ/10 (P-V) and λ/50 (RMS) are reached.

A relatively large aperture (375 mm) optical system working at f/1.6 for a low-light-level movable TV camera has been designed. In the process of designing, advantages and defects of a catadioptric system with all spherical surfaces and three kinds of aspherical systems have been compared. The optical system we finally adopted is a reflecting system with two aspherical surfaces. Its primary mirror is hyperboloid and the secondary is a high order planary aspherical surface. Maximal asphericity is 0.048 mm and 0.007 mm, respectively. There are also two small correcting lenses (crown and flint glass) near focus in order to correct curvature of field and astigmatism. Within 2.4 degree(s) field of view, spot diagrams show that the maximal image is 0.035 mm in diameter with a flat focal plane over the wavelength 4861 angstrom to 6563 angstrom. The total weight of the optical elements is about 14 Kg. The optical tube length is about 277 mm and its T/Number is 2.

In this paper, several collimator systems that may be used in the IR region with no central obscuration are discussed. One of them is a two-mirror asymmetrical system with the secondary of high order asymmetrical surface. The system has been realized in practice. Optical design shows that the image spot is diffraction limited at the center of field, and is about 1.8 arcsec at the margin of +/- 0.6 degree(s) field. Due to technological defect, the real image spot is about 1.8 arcsec at the center and 4.2 arcsec at the margin of field.