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We present atomic-resolution images of TiSe $_2$ , MoTe $_2$ and TaS $_2$ single crystals in liquid condition using our home-built scanning tunneling microscopy (STM). By facilely cleaving of single crystals in liquid, we were able to keep the fresh surface not oxidized within a few hours. Using the high-stable home-built STM, we have obtained atomic resolution images of TiSe $_2$ accompanied with the single atom defects as well as the triangle defects in solution for the first time. Besides, the superstructure of MoTe $_2$ and hexagonal charge-density wave domain structure in nearly commensurate phase of TaS $_2$ were also obtained at room temperature (295 K). Our results provide a more efficient method in investigating the lively surface of transition metal dichalcogenides. Besides, the high stable liquid-phase STM will support the further investigations in liquid-phase catalysis or electrochemistry.

We present a homebuilt scanning tunneling microscope (STM) which employs an inner-wall polished sapphire guiding tube as a rail for the scanner to form a short tip-sample mechanical loop. The scanner is mounted on a square rod which is housed in the guiding tube and held by a spring strip. The stiff sapphire guiding tube allows the STM body to be made in a simple, compact and rigid form. Also the material of sapphire improves the thermal stability of the STM for its good thermal conductivity. To demonstrate the performance of the STM, high quality atomic-resolution STM images of high oriented pyrolytic graphite were given.

We have used a homebuilt scanning tunneling microscope (STM) to observe an atomically resolved underlying edge dislocation that occurred in the second layer of graphite. It showed evidence of variable interactions between the topmost two layers near the dislocation edge. Through a special thermal process, we will further demonstrate a variety of STM features scanned near grain boundaries. A collective interference model was proposed to explain these features. It views an STM image as the interference result of the electron waves in the first layer scattered by the potentials that come from the atoms in the first two layers with the second layer contribution being modified by some interlayer interaction factors. This model could correctly simulate all the observed features and revealed that the degree of the interlayer interaction could be quantitatively reflected by the bright-to-dark size ratio of the bright-dark pair at a lattice site. It thus provides a method of quantitatively studying interlayer interactions at the atomic level.

A homebuilt low-temperature scanning tunneling microscope (STM) featuring a detachable scanner based on a double slider design, along with a reliable transfer mechanism for tip and sample exchange, is present. The coarse motor is decoupled from the scanner, which prevents the motor instabilities including vibrations and drifts from entering the tip-sample loop and thus improves the performance of the STM. In addition, in situ exchange of tips and samples can be implemented easily and reliably using a winch-type transfer mechanism. Atomically resolved images on graphite are demonstrated to show the performance of the proposed STM.

To alleviate the problems of casing collapse induced by the coupling effect of rock salt creep and casing wear, the effects of salt creep, attrition rate and casing abrasive position on the equivalent stress on casings in non-uniform in-situ stress field is analyzed by finite-difference model with worn casing, cement and salt formation. It indicates that, creep reduces the yield strength of worn casing to a certain extent; Equivalent stress on casings is bigger and more non-uniform when the abrasion is more serious; Wear position obviously changes the distribution of equivalent stress on casing, and when the wear located along the direction of the minimum in-situ stress, equivalent stress on casing could be the largest that leads to the casing being failed more easily. Equivalent stress on casings increases gradually with creep time increasing and will get to balance in one year or so; In addition, new conclusions are obtained which are different from before: the maximum equivalent stress on casings is in the direction of the minimum horizontal stress, only when the attrition rate of the casing is little; otherwise, it is not. This method could help to improve the wear prediction and design of casings.

We present a new stacked TunaDrive motor with two intact piezoelectric stacks being spring-clamped by a pair of parallel highly polished zirconia ceramic rods. Compared with the earlier version we presented with five stacks, it has a simpler and more compact structure and is much easier to build. Although the usage of piezoelectric material is cut by ∼35%, the motor can still provide a large output force of ∼1.92 N, which is nearly the same as that of the earlier version. The simple and symmetrical structure, high rigidity, and large output force make the new motor an ideal tool for coarse approach with nanometer precision.

An industrial mutant of Streptomyces avermitilis produced avermectin at a high level in industrial complex culture medium. However, almost no avermectin was detected in the cultures of tryptone soya broth (TSB). Its wild-type strain could not synthesize avermectin. To elucidate the regulatory mechanism about avermectin production, proteomic analysis of S. avermitilis was carried out. Results showed that during avermectin biosynthesis, fatty acid metabolism and TCA cycle were repressed. Partial enrichment of glycolytic pathway indicated the critical role of glucose catabolism during avermectin biosynthesis. Some enriched enzymes in amino acid metabolic pathways (glnA, leuC) confirmed the leucine as the possible precursor of avermectin. Highly expressed stress or stress-related proteins indicated a global regulation mechanism at the onset of avermectin production. And highly expressed morphology control proteins revealed an association between hyphal morphology and avermectin production. Further, this study proofed strengthened capability to utilize carbon and nitrogen source in the industrial strain. Some stress or stress-related proteins (eshA, clpC, dnaK and grpE) expressed at low level in the industrial strain cultivated in non-production medium (lower than that in the wild-type strain), but these highly expressed at the onset of avermectin production. More sensible response to environmental stress may be responsible for it.