scholarly journals The Microstructure and Mechanical Properties of Poplar Catkin Fibers Evaluated by Atomic Force Microscope (AFM) and Nanoindentation

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 938 ◽  
Author(s):  
Wu ◽  
Wu ◽  
Shi ◽  
Chen ◽  
Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Cell Structure ◽  
Large Cell ◽  
Populus Tomentosa ◽  
Thin Wall ◽  
Cell Lumen ◽  
Atomic Force ◽  
Microstructure And Mechanical Properties ◽  
Wall Cell

In this study, the microstructure and mechanical properties of poplar (Populus tomentosa) catkin fibers (PCFs) were investigated using field emission scanning electron microscope, atomic force microscopy (AFM), X-ray diffraction, and nanoindentation methods. Experimental results indicated that PCFs had a thin-wall cell structure with a large cell lumen and the hollow part of the cell wall took up 80 percent of the whole cell wall. The average diameters of the fiber and cell lumen, and the cell wall thickness were 5.2, 4.2, and 0.5 µm, respectively. The crystallinity of fibers was 32%. The AFM images showed that the orientation of microfibrils in cell walls was irregular and their average diameters were almost between 20.6–20.8 nm after being treated with 2 and 5 wt.% potassium hydroxide (KOH), respectively. According to the test of nanoindentation, the average longitudinal-reduced elastic modulus of the PCF S2 layer was 5.28 GPa and the hardness was 0.25 GPa.

scholarly journals Variation of Burkholderia cenocepacia cell wall morphology and mechanical properties during cystic fibrosis lung infection, assessed by atomic force microscopy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
A. Amir Hassan ◽  
Miguel V. Vitorino ◽  
Tiago Robalo ◽  
Mário S. Rodrigues ◽  
Isabel Sá-Correia
Keyword(s):  
Mechanical Properties ◽  
Cystic Fibrosis ◽  
Atomic Force Microscopy ◽  
Cell Wall ◽  
Adaptive Evolution ◽  
Burkholderia Cenocepacia ◽  
Force Microscopy ◽  
Atomic Force ◽  
Morphology And Mechanical Properties

Abstract The influence that Burkholderia cenocepacia adaptive evolution during long-term infection in cystic fibrosis (CF) patients has on cell wall morphology and mechanical properties is poorly understood despite their crucial role in cell physiology, persistent infection and pathogenesis. Cell wall morphology and physical properties of three B. cenocepacia isolates collected from a CF patient over a period of 3.5 years were compared using atomic force microscopy (AFM). These serial clonal variants include the first isolate retrieved from the patient and two late isolates obtained after three years of infection and before the patient’s death with cepacia syndrome. A consistent and progressive decrease of cell height and a cell shape evolution during infection, from the typical rods to morphology closer to cocci, were observed. The images of cells grown in biofilms showed an identical cell size reduction pattern. Additionally, the apparent elasticity modulus significantly decreases from the early isolate to the last clonal variant retrieved from the patient but the intermediary highly antibiotic resistant clonal isolate showed the highest elasticity values. Concerning the adhesion of bacteria surface to the AFM tip, the first isolate was found to adhere better than the late isolates whose lipopolysaccharide (LPS) structure loss the O-antigen (OAg) during CF infection. The OAg is known to influence Gram-negative bacteria adhesion and be an important factor in B. cenocepacia adaptation to chronic infection. Results reinforce the concept of the occurrence of phenotypic heterogeneity and adaptive evolution, also at the level of cell size, form, envelope topography and physical properties during long-term infection.

Effect of Casting Design to Microstructure and Mechanical Properties of 5 mm TWDI Plate

2012 ◽  
Vol 152-154 ◽  
pp. 1607-1611 ◽  
Author(s):  
Johny Wahyuadi Soedarsono ◽  
Bambang Suharno ◽  
Rianti Dewi Sulamet-Ariobimo
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Skin Effect ◽  
Raw Material ◽  
Carbide Formation ◽  
Thin Wall ◽  
Gating System ◽  
Nodule Count ◽  
Microstructure And Mechanical Properties ◽  
Casting Design

In producing thin wall ductile iron (TWDI) cooling rate must be strictly maintained to prevent carbide formation. There are many ways to control cooling rate BUT the most independent one is by casting design. By choosing this parameter major changes in equipment and raw material used in the foundry can be avoided. This paper discusses the effect of gating system design on microstructure and mechanical properties of 5 mm TWDI plate. A casting design based on vertical gating system is made to produce 1, 2, 3, 4, and 5 mm TWDI plates. Plate with 5 mm thickness becomes an interesting subject due to its position as the thickest and furthest from ingate in casting design with a new concept. There are three designs coded as T1, T2, and T3. These three designs were also used in making 1 and 3 mm TWDI plates of which the result has been published. The plate with 5 mm thickness will be used for automotive components. Casting design simulation for filling flow and solidification were conducted with Z-Cast. Result of flow simulation shows that the filling flow happens in two kinds. Result of solidification shows that T3 has the highest solidification rate. In the experiment, the moulds used were furan sand. Experiment result shows that all the designs have microstructure consisting of nodule graphite in ferrite matrix, no trace of carbide and skin effect are formed. Skin effect length is various for all designs. The highest nodularity is only 72% and nodule count shows only 700 nodules/mm2. Brinell hardness number for all design is beyond standard given by JIG G5502. As for UTS and elongation none of the designs exceed the minimal standard. Experiment results confirms simulation result. Compared to the previous result nodularity and nodule count decrease and curve trends for every result are not similar.

The Effect of Vertical Step Block Casting to Microstructure and Mechanical Properties in Producing Thin Wall Ductile Iron

2013 ◽  
Vol 789 ◽  
pp. 387-393 ◽  
Author(s):  
Rianti Dewi Sulamet-Ariobimo ◽  
Johny Wahyuadi Soedarsono ◽  
Is Prima Nanda
Keyword(s):  
Mechanical Properties ◽  
Ductile Iron ◽  
Plate Thickness ◽  
Thin Wall ◽  
Microstructure And Mechanical Properties ◽  
Casting Yield ◽  
Automotive Parts ◽  
Vertical Step ◽  
Casting Design ◽  
Filling And Solidification

Thin wall ductile iron (TWDI) is introduced to fulfill the needs of lighter material in automotive parts that will reduce fuel consumption. Problem occurs during the production of TWDI due to the casting thickness. TWDI casting thickness classified to below 5 mm. Many designs have been made to answer the problem in producing thin wall ductile iron. Soedarsono et al established vertical step block casting design. This design based on Y-block principle that allows direct pouring of liquid metal to the mold without passing any gating system. This design will increase casting yield. The parameter of this research is pouring basin placement to study the effect of plate arrangement to filling and solidification. This research is conducted to see the effect of pouring basin placement to microstructure and mechanical properties of TWDI. The Design is made to produce 5 plates with different thickness that is 1, 2, 3, 4, and 5 mm. All of the plates arranged parallel in line. Pouring basin located in 2 ways. The first type located pouring basin above the plate of 5 mm thickness while the second one located it above the plate with 1 mm thickness. The first type coded as T4 while the second coded as T5. The moulds made from furan sand. The result shows although cold shut occurred in both pouring basin placements due to pouring discontinuity but shrinkage only formed in T5 on its plate with 1 mm thickness. Microstructure of all the plates presented nodule graphite in pearlite matrix. Carbide and skin effects also detected. Average nodularity is above 80% while the nodule count is between 614 to 1269 nodule/mm2. Most of the Brinell hardness number exceeded maximum limit given by JIS G5502 but the UTS is below the minimum limit except for 3 mm plate thickness of T5. All elongation values below the minimum standard. The results confirm that pouring basin location is important in casting design following Y-Block principle.

Determining Mechanical Properties of Escherichia Coli by Nanoindentation

2012 ◽  
Vol 1424 ◽  
Author(s):  
C. A. Wright ◽  
C.J. Sullivan ◽  
B. Crawford ◽  
L.D. Britt ◽  
M.A. Mamun ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mechanical Properties ◽  
Cell Wall ◽  
Contact Area ◽  
Solute Concentration ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force ◽  
A Cell ◽  
Afm Cantilever

ABSTRACTEscherichia coli, like other gram-negative bacteria, is protected from the surrounding harsh environment by a cell wall consisting of the peptidoglycan and outer membrane. Whereas the cytoplasmic membrane is the selective barrier, the cell wall provides mechanical strength for the cell. As bacteria navigate various environments, osmotic pressure can change dramatically due to changes in local solute concentration. The peptidoglycan together with the cellular proteins mitigates the osmotic stress that would otherwise cause lysis. The mechanical properties of E. coli cells and its individual layers have been largely indeterminable until the recent development of probe-based measurement tools. Since their invention, scientists have reported significant data measuring elasticity, modulus, and stiffness using atomic force microscopy (AFM). Fundamentally, in order to determine these mechanical properties through probe-based techniques, the contact area and load should be well defined. The load can be precisely calculated through the AFM cantilever spring constant. However, the silicon tip contact area can only be estimated, potentially leading to compounding uncertainties. Therefore, we developed a methodology to determine nanomechanical properties of E. coli using a nanoindenter.

Effect of Casting Design to Microstructure and Mechanical Properties of 4 Mm Twdi Plate

2013 ◽  
Vol 702 ◽  
pp. 269-274 ◽  
Author(s):  
Rianti Dewi Sulamet-Ariobimo ◽  
Johny Wahyuadi Soedarsono ◽  
Bambang Suharno
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Skin Effect ◽  
Flow Simulation ◽  
Ferrite Matrix ◽  
Carbide Formation ◽  
Thin Wall ◽  
Gating System ◽  
Microstructure And Mechanical Properties ◽  
Casting Design

Casting design is chosen by Soedarsono et al to maintain cooling rate in producing thin wall ductile iron (TWDI). Cooling rate should be maintained to prevent carbide formation. This paper discusses the effect of gating system design on microstructure and mechanical properties of 4 mm TWDI plate. A casting design based on vertical gating system is made to produce TWDI plates with the thickness of 1, 2, 3, 4, and 5 mm. This vertical system allows plates to function as runner which will helps in preventing premature solidification. Three designs were made. These designs are coded as T1, T2, and T3. These three designs were also used in making 1, 2, 3, and 5 mm TWDI plates of which the result has been published. Z-Cast is used to conduct a casting design simulation for filling flow and solidification. The result of flow simulation shows that the filling flow is resulted in two kinds. The result of solidification specifies that the 4 mm TWDI plates solidify in the third place. The result of the experiment highlights that in all of the designs, which have microstructure and consisted of nodule graphite in ferrite matrix, no trace of carbide and skin effect are formed. The length of skin effect varies in all of the designs. The highest nodularity is only 80% while nodule count is 931 nodules/mm2. Brinell hardness number for all of the design is beyond the standard given by JIG G5502. As for UTS, yield strength and elongation none of the designs exceeds the minimal standard. The result of the experiment does not confirm the result of the simulation. In sum, compared to the previous result, the curve trends of 4 mm TWDI plates look similar to 2 mm TWDI plates.

Determination the Effect of Silver Nanoparticles on Gram-Positive Bacterial Cells by Atomic Force Microscopy

2012 ◽  
Vol 506 ◽  
pp. 202-205
Author(s):  
O. Ketchart ◽  
A. Treetong ◽  
P. Na-Ubon ◽  
N. Supaka
Keyword(s):  
Cell Wall ◽  
Cell Suspension ◽  
Ag Nanoparticles ◽  
Bacterial Cell ◽  
Cell Structure ◽  
Quantitative Measure ◽  
Bacterial Suspension ◽  
Bacterial Cells ◽  
Gram Positive ◽  
Atomic Force

The atomic force microscope (AFM) was employed to study the significant effects of silver (Ag) nanoparticles-treated on the elastic cell wall of bacteria. In this study, the exposed Staphylococcus aureus was grown at 37 °C for 14 h. The cultures were centrifuged and cell pellets were resuspended in Milli-Q water to prepare final bacterial suspensions. A drop of bacterial suspension was deposited on polydimethylsiloxane (PDMS) sheet and allowed to air dry at room temperature before imaging. The cell suspension was collected at certain time intervals from the beginning of the test. The morphology of the cell surface compares between without treatment and Ag-treated cell suspension was investigated. The force mappings were obtained for the PDMS substrate and for the bacteria while scanning obliquely. The contribution of the internal osmotic pressure, to obtain a quantitative measure for the elasticity of the cell wall, had to be estimated. The pyramid-shaped AFM tip indented into a soft cell and the resulting bacterial surface was flat, and irreversible changed of bacterial cell structure. The investigation is attempted to understand pronounced effect of Ag nanoparticles on the individual gram-positive bacterial cell after treated with Ag nanoparticles.

scholarly journals The Effect of Heat Treatment on the Microstructure and Mechanical Properties of 2D Nanostructured Au/NiFe System

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1077 ◽  
Author(s):  
Tatiana Zubar ◽  
Valery Fedosyuk ◽  
Daria Tishkevich ◽  
Oleg Kanafyev ◽  
Ksenia Astapovich ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Surface Layer ◽  
Near Surface ◽  
Force Microscopy ◽  
Thermally Activated ◽  
Atomic Force ◽  
Microstructure And Mechanical Properties ◽  
Internal Volume ◽  
Increasing Temperature

Nanostructured NiFe film was obtained on silicon with a thin gold sublayer via pulsed electrodeposition and annealed at a temperature from 100 to 400 °C in order to study the effect of heat treatment on the surface microstructure and mechanical properties. High-resolution atomic force microscopy made it possible to trace stepwise evolving microstructure under the influence of heat treatment. It was found that NiFe film grains undergo coalescence twice—at ~100 and ~300 °C—in the process of a gradual increase in grain size. The mechanical properties of the Au/NiFe nanostructured system have been investigated by nanoindentation at two various indentation depths, 10 and 50 nm. The results showed the opposite effect of heat treatment on the mechanical properties in the near-surface layer and in the material volume. Surface homogenization in combination with oxidation activation leads to abnormal strengthening and hardening-up of the near-surface layer. At the same time, a nonlinear decrease in hardness and Young’s modulus with increasing temperature of heat treatment characterizes the internal volume of nanostructured NiFe. An explanation of this phenomenon was found in the complex effect of changing the ratio of grain volume/grain boundaries and increasing the concentration of thermally activated diffuse gold atoms from the sublayer to the NiFe film.

Sign in / Sign up

Export Citation Format

Share Document