In this paper, a new way to prepare controlled nano-MgO with different morphology facilely by using modified attapulgite as hard template was found. The morphology details were investigated by scanning electron microscopy (SEM). It was found that the morphology of nano-MgO particles was induced by the ratio of attapulgite versus Mg 2+ . The lamella morphology of MgO was converted to sphere particles, then the rod-like and needle-like or fiber-like shape, while the content of attapulgite was raised.

Barite is an abundant sulfate mineral in nature. Especially, the variety of morphologies of barite is often driven by the mixing of Ba-bearing hydrothermal fluid and sulfate-bearing seawater around hydrothermal chimneys. In order to better understand the factors affecting the morphology and precipitation mechanism(s) of barite in seafloor hydrothermal systems, we synthesized barite by a new method of in-situ mixing of BaCl2 and Na2SO4 solutions at 200 °C while varying Ba concentrations and ratios of Ba2+/SO42−, and at room temperature for comparison. The results show that barite synthesized by in-situ mixing of BaCl2 and Na2SO4 solutions at 200 °C forms a variety of morphologies, including rod-shaped, granular, plate-shaped, dendritic, X-shaped, and T-shaped morphologies, while room temperature barites display relatively simple, granular, or leaf-like morphologies. Thus, temperature affects barite morphology. Moreover, dendritic barite crystals only occurred at conditions where Ba2+ is in excess of SO42− at the experimental concentrations. The dendritic morphology of barite may be an important typomorphic feature of barite formed in high-temperature fluids directly mixing with excess Ba2+ relative to SO42−.

We report the synthesis of single-crystalline α-Fe2O3 nanoflakes by the oxidation reaction of water vapor through a gas-solid method. The samples are characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), micro-Raman spectrometer, and transmission electron microscopy (TEM). As-synthesized nanoflakes have a pseudotriangle morphology: 20-50 nm in thickness, 0.5-1.5 μm in length and base-width. It is observed that vertically aligned arrays of leaf-like α-Fe2O3 grow at the verges of the iron foils. The possible mechanism is discussed to elucidate the formation of α-Fe2O3 nanostructures. The experimental results indicate that water vapor plays an important role in controlling the morphology of the final products.

Bacterial sample preparation is crucial for its observation by scanning electron microscopy (SEM). However, the current polylysine (PLL) method leads to bacterial morphological changes. To overcome this problem, we employed chitosan (CS) to coat coverslips to prepare bacteria for SEM and compared it with the PLL method. Coverslips coated with 0.025% (w/v) CS showed satisfactory bacterial binding ability. Within 30 min of binding time, the number of bacteria on CS-coated and PLL-coated coverslips exhibited no differences. Four bacteria strains were employed to compare the differences in SEM images between the two methods. Most of the bacteria showed irregular surface or sticky substances after settling on PLL-coated coverslips, while bacteria with clear surface texture were observed on CS-coated coverslips. Transmission electron microscopy (TEM) images showed deformed bacterial envelope on PLLcoated coverslips; meanwhile, similar intact envelope was observed from the bacteria on CS-coated coverslips and the bacteria without any treatment. The TEM results verified the morphological differences of SEM between the two methods. Except for morphology, the length of the rod-shaped bacteria was longer on CS-coated coverslips than that on PLL-coated coverslips, less shrinkage of the sample was observed, and CS could preserve the length of the rod-shaped bacteria better than PLL in its preparation for SEM. It is demonstrated that the low-cost CS could be utilized in bacterial preparation for SEM to acquire preferable images. Bacterial suspension with optical density at 600 nm of about 0.5, deposited on 0.025% CS-coated coverslips for 30 min, and followed by routine fixation, dehydration, and drying are optimal parameters.