There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

QIIME 2 development was primarily funded by NSF Awards 1565100 to J.G.C. and 1565057 to R.K. Partial support was also provided by the following: grants NIH U54CA143925 (J.G.C. and T.P.) and U54MD012388 (J.G.C. and T.P.); grants from the Alfred P. Sloan Foundation (J.G.C. and R.K.); ERCSTG project MetaPG (N.S.); the Strategic Priority Research Program of the Chinese Academy of Sciences QYZDB-SSW-SMC021 (Y.B.); the Australian National Health and Medical Research Council APP1085372 (G.A.H., J.G.C., Von Bing Yap and R.K.); the Natural Sciences and Engineering Research Council (NSERC) to D.L.G.; and the State of Arizona Technology and Research Initiative Fund (TRIF), administered by the Arizona Board of Regents, through Northern Arizona University. All NCI coauthors were supported by the Intramural Research Program of the National Cancer Institute. S.M.G. and C. Diener were supported by the Washington Research Foundation Distinguished Investigator Award.

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Reproducible, interactive, scalable and extensible microbiome data science using QIIME 2

Reactive oxygen species and antioxidant machinery in abiotic stress tolerance in crop plants

The recent advent of DNA sequencing technologies facilitates the use of genome sequencing data that provide means for more informative and precise classification and identification of members of the Bacteria and Archaea. Because the current species definition is based on the comparison of genome sequences between type and other strains in a given species, building a genome database with correct taxonomic information is of paramount need to enhance our efforts in exploring prokaryotic diversity and discovering novel species as well as for routine identifications. Here we introduce an integrated database, called EzBioCloud, that holds the taxonomic hierarchy of the Bacteria and Archaea, which is represented by quality-controlled 16S rRNA gene and genome sequences. Whole-genome assemblies in the NCBI Assembly Database were screened for low quality and subjected to a composite identification bioinformatics pipeline that employs gene-based searches followed by the calculation of average nucleotide identity. As a result, the database is made of 61 700 species/phylotypes, including 13 132 with validly published names, and 62 362 whole-genome assemblies that were identified taxonomically at the genus, species and subspecies levels. Genomic properties, such as genome size and DNA G+C content, and the occurrence in human microbiome data were calculated for each genus or higher taxa. This united database of taxonomy, 16S rRNA gene and genome sequences, with accompanying bioinformatics tools, should accelerate genome-based classification and identification of members of the Bacteria and Archaea. The database and related search tools are available at www.ezbiocloud.net/.

Introducing EzBioCloud: a taxonomically united database of 16S rRNA gene sequences and whole-genome assemblies.

The invention relates to a sediment discharging device of a center water tank of a cooling tower. A rotary spiral sediment discharging blade is coaxially mounted in the center water tank; a gap delta1 is reserved between a lower edge of the blade and a bottom face in the water tank, and the delta1 is equal to 2D/h+phi1h1/phi2h2 mm; a gap delta2 is reserved between an outer edge of the blade and an inner side face of the center water tank, and the delta2 is equal to 5D/h mm; in above two formulas, D is an internal diameter of the center water tank; h is a center internal height of the center water tank; phi1 is a water density, and phi2 is a sediment density; and h1 is a water basin design water level height of the tower, and h2 is a sediment design storing height; a downwards-inclined and outwards-inclined sediment discharging pipe is arranged on a conical face of the bottom face of the center water tank; a pipe diameter of the sediment discharging pipe is an inclination length of the conical face; and an upper end of the sediment discharging pipe is communicated with the bottom face of the center water tank, and a lower end of the sediment discharging pipe is provided with a flange and a sealing cover hinged with the flange. With the adoption of the sediment discharging device, the various technical problems of sediment discharge of the center water tank of the cooling tower can be solved. The sediment discharging device has the characteristics of simple structure, good sediment effect and the like.

Sediment discharging device of center water tank of cooling tower

Based on the first-principles method, the polarity inversion mechanism of Al-doped ZnO grown on sapphire (0001) substrate was investigated. This study revealed that the Al dopant tends to float on the surface of the buffer layer and leads to form ZnO nucleation islands of Zn-polarity without changing in-plane orientation. Finally, these islands evolve to wall-like nanostructure with Zn-termination. The results can explain the reason of the polarity inversion phenomenon in the experiment and supply more information for controlling the ZnO growth polarity.

https://iopscience.iop.org/article/10.1209/0295-5075/114/66003/pdf

A first-principles study on Al-doped ZnO growth polarity on sapphire (0001) surface

The invention relates to a pressure equalizing device of fixed spraying systems, and the device comprises a conical shell, a float switch, a regulating spring, a nozzle and a bracket The nozzle and a water inlet pipe are connected by virtue of the conical shell; the regulating spring is arranged at the bracket which is positioned at the bottom of the inner side of the conical shell; the float switch is connected with the regulating spring and can slide back and forth along a guide rail which is fixed between the top in the conical shell and the bracket at the bottom in the conical shell; in order to reduce the incoming flow impact loss, the upper tip part of the float switch is arc-shaped By adopting the conical shell, the float switch and the regulating spring of different sizes, the device can be matched with the nozzles of various fixed spraying systems for use so as to uniformize the pressure and speed of the inlet of each nozzle When the pressure and speed of the nozzle inlets are the same, the water sprayed by the nozzle can be the same in flow and spray radius so as to achieve the aim of equalizing the water distribution

Pressure equalizing device of fixed spraying systems

Control-flow integrity (CFI) is a general method for preventing code-reuse attacks, which utilize benign code sequences to achieve arbitrary code execution. CFI ensures that the execution of a program follows the edges of its predefined static Control-Flow Graph: any deviation that constitutes a CFI violation terminates the application. Despite decades of research effort, there are still several implementation challenges in efficiently protecting the control flow of function returns (Return-Oriented Programming attacks). The set of valid return addresses of frequently called functions can be large and thus an attacker could bend the backward-edge CFI by modifying an indirect branch target to another within the valid return set. This article proposes RAGuard, an efficient and user-transparent hardware-based approach to prevent Return-Oreiented Programming attacks. RAGuard binds a message authentication code (MAC) to each return address to protect its integrity. To guarantee the security of the MAC and reduce runtime overhead: RAGuard (1) computes the MAC by encrypting the signature of a return address with AES-128, (2) develops a key management module based on a Physical Unclonable Function (PUF) and a True Random Number Generator (TRNG), and (3) uses a dedicated register to reduce MACs’ load and store operations of leaf functions. We have evaluated our mechanism based on the open-source LEON3 processor and the results show that RAGuard incurs acceptable performance overhead and occupies reasonable area.

https://dl.acm.org/doi/pdf/10.1145/3280852

RAGuard: An Efficient and User-Transparent Hardware Mechanism against ROP Attacks

The invention discloses a polyketide and a preparation method and application thereof. The structural formula of the polyketide provided by the invention is shown in the formula I in the specification. The preparation method is characterized by utilizing trichoderma koningii MF349. The polyketide is suitable for preparing the products inhibiting mycobacterium tuberculosis. The method is simple and convenient in process, and the product has high yield and has correct structure through nuclear magnetic detection.

Lixin Zhang

Papers

Sediment discharging device of center water tank of cooling tower

A first-principles study on Al-doped ZnO growth polarity on sapphire (0001) surface

Pressure equalizing device of fixed spraying systems

RAGuard: An Efficient and User-Transparent Hardware Mechanism against ROP Attacks

Polyketide and preparation method and application thereof