Modifikasi Sifat Mineralogi dan Fisiko-Kimia Bahan Tanah Vertik dengan Ball Mill Berenergi Tinggi

test of modifying the properties of vertic material by using a ball milling technique was carried out with the primary aim to eliminate the vertic (swelling-shrinking) property and increase the electrical charge of the material. The clay fraction of Vertisol was dried and ball milled for 5, 10, and 20 minutes. Results reveal that the clay fraction of the soil material was dominated by montmorillonite mineral, and ball milling for > 5 minutes transformed the crystalline montmorillonite into amorphous (non-crystalline) particles. Those changes were followed by increasing the vertic features, cation exchange capacity, water holding capacity, and suspension effect of the milled material. The improvement of vertic characteristics might be due to the increase of electric charge of the milled particles. Thus, high-energy ball milling was an effective technique to improve the reactivity and vertic property of vertic material of Vertisols. Further studies are needed to evaluate the potential uses of modified vertic materials as ceramic material, cement component, adsorbent of heavy metals, and other contaminants, or catalysator

Retention forces between primary and secondary CAD/CAM manufactured telescopic crowns: an in vitro comparison of common material combinations

Objectives To analyze the retention forces between primary and secondary telescopic crowns milled from various materials and to compare them with the retention forces between cast telescopic crowns made of precious metal alloys. Materials and methods Primary and secondary crowns (N = 60; n = 10 per group) were fabricated using various material combinations (1: zirconia [ZIR]/polyether ether ketone [PEEK]; 2: titanium grade IV [TI]/PEEK; 3: PEEK/PEEK; 4: non-precious alloy [NPA]/PEEK; 5:NPA/NPA), while precious alloy (PA) was used for the control group (6: PA/PA). The retention forces at 10, 1000, 5000, and 10,000 connection and disconnection cycles and the relative weights were analyzed, applying nonparametric repeated measures ANOVA and post hoc Mann–Whitney and Wilcoxon signed-rank tests (α < 0.05). Results Globally, significant differences in the retention forces among the materials (p < 0.0001), time points (p < 0.0001), and wear resistance for the various materials (p < 0.0001) were observed. No significant changes in retention forces compared to baseline were observed in groups 2, 4, 5, and 6. A significantly higher weight loss for both primary and secondary crowns was observed in groups 4 and 6. Conclusions The material combination in telescopic attachments influences retention forces and wear. Interactions between materials and time were evident, indicating that the change in retention forces differs among the materials. The combinations of milled TI/PEEK and NPA/NPA qualify for further preclinical testing in a more clinically realistic setup, determining a material-specific double-crown design. Clinical relevance The design of precious alloy telescopic crowns cannot be directly transferred to other milled material combinations due to different retention behaviors.

Dissolution of wood components during hot water extraction of birch

Autohydrolysis-based pretreatments enable extraction of hemicellulose from wood tissue prior to the paper pulp cooking processes enabling their further use as platform chemicals and in material applications. In this study, hot water extraction of birch meal was conducted in a small flow-through system. The combination of high surface area of the milled material with increased driving force induced by constant flow of freshwater, together with fast evacuation of extract, enabled a detailed study of the dissolution process. Based on the findings, deeper insight into acidification and autohydrolysis progress was obtained.

Optimization Issues of a Hammer Mill Working Process Using Statistical Modelling

Our paper presents the hammer mill working process optimization problem destined for milling energetic biomass (MiscanthusGiganteus and Salix Viminalis). For the study, functional and constructive parameters of the hammer mill were taken into consideration in order to reduce the specific energy consumption. The energy consumption dependency on the mill rotor spinning frequency and on the sieve orifices in use, as well as on the material feeding flow, in correlation with the vegetal biomass milling degree was the focus of the analysis. For obtaining this the hammer mill was successively equipped with 4 different types of hammers that grind the energetic biomass, which had a certain humidity content and an initial degree of reduction ratio of the material. In order to start the optimization process of hammer mill working process, 12 parameters were defined. The objective functions which minimize hammer mill energy consumption and maximize the milled material percentage with a certain specific granulation were established. The results obtained can serve as the basis for choosing the optimal working, constructive, and functional parameters of hammer mills in this field, and for a better design of future hammer mills.

Downhole Lithological Profile Reconstruction Based on Chemical Composition of Core Samples and Drill Cuttings Measured with Portable X-ray Fluorescence Spectrometer

The reconstruction of a lithological profile based on geophysical logs of chemical composition provided by geochemical gamma-gamma well logging probes has been increasingly used for geophysical interpretation. A chemical profile, analogous to the measurements mentioned above, can be determined based on measurements made with a portable X-ray fluorescence spectrometer (pXRF). This paper presents a methodology for determining the mineral composition of drilled, clastic, as well as clay-rich rocks on the basis of both inexpensive and timesaving pXRF measurements as well as models combining the results of chemical composition analysis with results of mineral composition analysis (XRD). The results of chemical composition analysis obtained with a portable XRF spectrometer were calibrated based on a detailed analysis produced with ICP-OES and ICP-MS methods. A significant advantage of the proposed method is the possibility to apply it with regard to drill cuttings as well as archival cores. However, considerable discrepancies in the results obtained were identified while comparing the results of chemical composition analysed directly on the core and milled material. The analysed material comprised Carboniferous rocks derived from three boreholes located in Poland: Kobylin-1 as well as Biesiekierz-1 and -2. It was possible to directly compare the lithological profile obtained based on measurements taken on drill cuttings with the results of the lithological interpretation of a geochemical probe log.

Influence of Milled Material and Construction Waste on the Properties of a Typical Soil of Iranduba City - AM / BR

The lack of stone material in the State of Amazonas and the possibility of using solid waste in the sublayers of pavements motivates the work in question, notably with the purpose of contributing as an alternative technical solution to the paving of the city of Iranduba / AM / BR. Compositions of soil mixed with waste from milled material (MM) and construction and demolition (CDW) were studied. The materials participating in the formulations were physically characterized, as well as the mechanical behavior of the natural soil (NS) and mixtures of soil-20% milled material (NS + 20MM) and soil-20% construction and demolition waste were determined. (NS + 20CDW). The results showed that the compositions with the participation of the milled material were the most efficient relative to the mixtures with the presence of the construction and demolition residue. It is noteworthy that both formulations, referring to natural soil, improved the expansion and presented an increase in the California Bearing Ratio, selection parameters for application in the base and subfloor layers.

Characterization of Mn-Doped Vanadium Phosphorus Oxide (VPO) Catalyst: Effect of Ball Milling

<p>The effect of ball milling on the structure and surface reactivity of the Mn-doped vanadium phosphorus oxide (V–P–O) catalyst is discussed. Mn-doped VOHPO₄·½H₂O precursor was prepared via organic method. The precursor was ball milled in isopropyl alcohol using agate balls for 60 min at 800 rpm. XRD, BET surface area measurements, SEM, O₂-TPD, H₂-TPR and TPD of NH₃ were used to characterize properties of the final catalysts. The results revealed that mechanical treatment of Mn-doped V–P–O catalyst increased surface area as well as reduced particle size of the material. Furthermore, process also increased exposure of (001) crystallographic plane of VOHPO4·½H₂O precursor. The secondary structure of the milled material is also lost. The total amount of oxygen desorbed (from O₂-TPD) and removed (by H₂-TPR) from milled material is higher compared to the unmilled one. The surface acidity of the catalyst was also increased after milling process, as evidenced by lower desorption temperature and higher total amount of the ammonia desorbed.</p>

Implementation of a Controllable Damper for Suppressing Vibration in the Technological Process

The paper deals with the problem of suppressing vibration of the arm of Motoman SSF200 robot within the frame of the technological process. Based on an overview of literature, a semi-active vibration control system was selected and a double ended magnetorheological damper (MR) was designed. After testing the acceleration of the robot arm in milling operation without the MR damper, the device was employed and the acceleration of the robot arm in four operation modes was experimentally tested.The conducted research has proved that the double ended MR damper can be practically applied for suppressing the vibration of the robot arm. The higher power to the electromagnet of the MR damper is exposed, the better vibration suppression is. This means that by changing the strength of current, the technological process of the robot arm is under control. Thus, control over the technological process is simplified when the physical characteristics of the milled material, milled tool or operation vary.