Wear Behaviors of Stainless Steel and Lubrication Effect on Transitions in Lubrication Regimes in Sliding Contact

The wear behavior of AISI304 stainless steel was investigated under dry, water-, and oil-lubricated conditions. A block-on-disk wear test was conducted in this work, since the test conditions could be controlled easily. For oil-lubricated contact, a significant amount of thin and elongated cutting chip-like debris was observed. This is attributed to the high lubricating effect of oil. Strain-induced martensitic (SIM) transformation was observed for all AISI304 blocks after the wear test, while AISI304 consisted of a single γ-austenite phase prior to the wear test. The Stribeck curve and the corresponding lubrication regimes were also considered to explain the wear behaviors and lubrication effect of AISI304. In comparison to the dry or water-lubricated conditions, which fall in the boundary lubrication regime at a low rotation speed, it is considered that the high viscosity of the oil-based lubricant causes the lubrication condition to enter the mixed lubrication regime early at a lower speed, thus reducing the specific wear rate over the 100–300 rpm range.

Studies on the Mechanical Properties of Dry, Saturated, and Frozen Marls Using Destructive and Non-destructive Laboratory Approaches

The mechanical properties of frozen rocks vary significantly from the properties of the same lithology under ambient temperature. The goal of this paper is to investigate these changes in the physical and mechanical properties of rocks due to saturation and freezing. Besides, the attention was paid on discovering new correlations between the mechanical characteristics. To fulfill these objectives, 36 uniaxial compressive strength tests, 36 Brazilian splitting tests, and 48 point load tests were carried out. The samples were tested in air dry, water saturated, and frozen (− 20 °C) conditions. The measured physical and mechanical parameters were analyzed by using regression analyses. It was found that the average uniaxial compressive strength of frozen samples (21.93 MPa) is 86.4% more than saturated ones (11.76 MPa) but 25.9% less than dry specimens (29.62 MPa). Additionally, high correlations were established between uniaxial compressive strength and IS(50) under air-dry, saturated, and frozen conditions for the investigated marl samples. Furthermore, it is of particular interest to observe a high correlation with the determination coefficient (R2 = 0.95) between the constants of previously published linear regressions of UCS- Is(50) under dry status.

Optimizing methods to characterize caffeic, ferulic, and chlorogenic acids in Salicornia sinus-persica and Salicornia bigelovii extracts by tandem mass spectrometry (LC-MS/MS)

Three types of phenolic acids (caffeic, ferulic, and chlorogenic acid) were identified and quantified in two halophytic plants (Salicornia bigelovii and Salicornia sinus-persica). Analysis was performed using a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) system via the standard addition method. The matrix effect (ME), recovery efficiency (RE), and process efficiency (PE) parameters were evaluated for S. bigelovii extracts, which revealed a strong ME on the ionization of the three acids. The matrix had little to no effect on the extraction step for all samples. The quantitation results revealed that S. bigelovii was more abundant in the acids analyzed (total of 319.2 µg/g dry water extract) when compared to S. sinus-persica (117.2 µg/g dry water extract), and chlorogenic acid was the dominant component. The extractives content was high in both plants, representing over 35% of the dry plant weight. All the extracts exhibited antioxidant activity toward both DPPH and ABTS radicals at levels comparable to other medicinal plants.

ANALISA KUALITAS BRIKET ARANG (STUDI KASUS TANAMAN BAMBU DI HUTAN PENDIDIKAN DESA HONITETU KABUPATEN SERAM BAGIAN BARAT)

This study aims to analyze the relationship between bamboo (Javanese bamboo species (Schizostachyum brachycladum), petung bamboo (Dendrocalamus asper) and suanggi bamboo (Schizostachyum arundinaceae)] with pressure (3 tons, 2.5 tons and 2 tons treatment) on the quality of charcoal briquettes. The research procedure begins with the preparation of raw materials, drying, curing, grinding, adhesion, printing and pressing, drying briquettes and determining the quality of the briquettes. This study used a Completely Randomized Design (CRD) arranged in factorial with 3 replications where the factors studied were 2 factors: factor A (bamboo type) and factor B (pressure). The results showed that the analysis of bamboo species diversity (A) affected the air-dry water content and the heating value, pressure factor (B) and interaction (AB) affected the roughness of air-dried water while the other parameters did not affect. The value of dry air content ranges between 6.55-6.62%, Dry oven water levels range between 3.426-3.446%, ash content ranges between 4.154-4.240%, volatile substance levels range between 7.64-7.99%, bonded carbon content ranges between 60.295-60.456% and and heating value ranges from 4336.28-4833.24 cal/g. Research Results Meet SNI Standards SNI 01-6235-2000.

INVESTIGATION OF THE THERMAL CONDUCTIVITY OF AUTOCLAVED AER ATED CONCRETE

The results of measuring the thermal conductivity coefficients of autoclaved aerated concrete grades D450 and D600 in the dry, water-saturated and frozen state are presented.

Distinguishing between rheophysical regimes of fluid-saturated granular-flows using dilatancy and acoustic emission measurements

Dry granular flows provide an ongoing challenge to physics and under saturation the multiphase physics is even more difficult to disentangle. A rich literature has elucidated the possible regimes achieved, however, the nonlinear nature of the multiphase process makes predicting the appropriate dynamic regime difficult. In this study, we introduce a new experimental strategy to identify the appropriate dynamical regimes by combining traditional methods with acoustic emission measurements. We sheared natural granular materials under dry, water and oil-saturated conditions while recording mechanical, acoustic and visual data. By applying alternate low and high velocity steps we respectively obtained quasi-static and inertial granular flow regimes. Dilation was observed for all high-velocity flows but its amount varied as did the degree of acoustic emission. At high velocities, the water-saturated flow dilated less and had reduced acoustic emissions relative to the dry case. In contrast, the oil-saturated flow dilated more while having even less acoustic emissions. This difference in trends of the dilation and acoustic emissions with increasing fluid viscosity suggests that oil and water granular flows achieved distinct dynamical regimes. Damping of granular pressure by reducing grain collisions and Dilatancy due to fully lubricated contacts are two competing processes influence the saturated shear physics and theoretically expected, but distinguishing between the regimes is difficult to anticipate. The acoustic emissions provide an extra piece of information that allows us to distinguish the physical regimes and determine the competition between processes that control the physics of saturated granular flows in the granular inertial regime.