Effect of Wearing Different Types of Face Mask to Heat Strain During Physical Activities

There is a concern to use masks during physical activities when exercising and working. Wearing masks during physical activity will pose a risk to physiological changes in the body and human heat strain by the principle of a mask can block the respiratory tract. This study aims to determine how much the human physiological changes quantitatively and qualitatively when using different types of medical masks, cloths and N95. There were 10 respondents as a sample of this study. The results obtained show that the different types of masks to the physiological response of the human body, cloth masks can affect the physiological changes the highest compared to medical masks and N95. The subjective response in the form of thermal comfort, mask sensation, and thermal sensation shows that of the 3 types of masks, the N95 mask is the mask that is the most uncomfortable when worn. The recommendations of the 3 types of masks are medical masks because they affect the slightest increase in the risk of heat stress while the cloth masks have the highest increase in tympanic temperature and Physiological Strain Index

PERANCANGAN PRODUK KAKI PROSTETIK BAWAH LUTUT BERDASARKAN BERBAGAI KRITERIA PENGGUNA USIA 15-64 TAHUN

Amputasi kaki bawah lutut merupakan salah satu penyebab disabilitas. Penyandang disabilitas atau difabel memerlukan alat bantu untuk dapat beraktivitas secara normal. Salah satu peralatan kesehatan yang dapat membantu mobilitas penyandang disabilitas amputasi kaki adalah kaki prostetik. Evaluasi rancangan produk dilakukan menggunakan Prosthetic Evaluation Questionnaire. Hasil evaluasi dijadikan landasan perancangan produk untuk menjawab kebutuhan pengguna. Setelah diketahui nilai evaluasi produk, selanjutnya dilakukan perancangan ulang produk berdasar ekspektasi pengguna dengan mempertimbangkan masukan expert sebagai acuan. Proses perancangan menggunakan metode pairwise comparison untuk mengetahui bobot kebutuhan yang diharapkan pengguna. Hasil pembobotan digunakan untuk mengevaluasi konsep produk yang diusulkan menggunakan metode Quality Function Deployment (QFD). Perancangan ulang produk menghasilkan spesifikasi produk yang dapat mengakomodir kebutuhan pengguna. Produk yang dihasilkan menggunakan bentuk endoskeleton, socket silicon, telapak kaki rigid dan terbuat dari material kayu dan spons. Produk yang dihasilkan memiliki beberapa keunggulan dibanding produk kaki prostetik referensi, diantaranya struktur kaki prostetik yang lebih kuat, perawatan lebih mudah, serta ketahanan yang lebih baik

PENGARUH KONSENTRASI PROTEIN PADA PELUMAS TERHADAP KEAUSAN ULTRA HIGH MOLECULAR WEIGHT POLYETHELENE (UHMWPE) UNTUK APLIKASI SENDI LUTUT TIRUAN

Polimer UHMWPE telah digunakan secara luas sebagai komponen tibial berpasangan dengan titanium alloy, stainless steel(SS), cobalt chrom alloy dan ceramic sebagai komponen femoral pada sendi lutut tiruan. Bovine Serum(BS) digunakan sebagai pelumas karena memiliki karakter yang mirip dengan pelumas sendi. Penelitian ini bertujuan melihat pengaruh konsentrasi protein dalam BS sebagai pelumas pada sendi lutut tiruan terhadap keauasan UHMWPE yang bergesekan dengan SS 316L. Penelitian ini menggunakan bahan UHMWPE virgin dan SS 316L yang diimplantasi dengan ion nitrogen dengan energi 100 KeV, arus 100 μA, waktu implantasi 90 menit. Pengujian menggunakan mesin undirectional pin on flat (POF) dengan kecepatan 70 mm/s, beban 180 N dan volume pelumas 15 ml selama 360 jam. BS sebagai pelumas divariasikan konsentrasi proteinnya 30 g/l dan 50 g/l ditambahkan sodium azide(NaN3) 0,2% - 0,3% g/l sebagai anti bakteri. Hasil penelitian ini memperlihatkan bahwa faktor keausan UHMWPE virgin berpasangan dengan SS 316L implantasi tidak menunjukkan perbedaan yaitu 6,59 x 10-8 mm3/Nm pada konsentrasi protein 30 g/l dan 50 g/l. Kata kunci : UHMWPE, SS 316L, Bovine serum, faktor keausa

Effect of Bombyx mori silk-fiber volume on flexural strength of fiber-reinforced composite

Dental glass fiber is one of dental synthetic fibers that are widely used in dentistry as a dental resin reinforcement, such as in dentin replacement material. The availability of glass fiber is limited in Indonesia because it must be imported and relatively expensive. Bombyx mori silk-fiber is one of the strongest natural fiber derived from silkworm cocoon processing. Silk-fiber is used in medical applications as a post-surgical sutures, scaffolds for tissue engineering and drug delivery. The purpose of this study was to evaluate the effect of Bombyx mori silk-fiber volume on the flexural strength of fiber-reinforced composite (FRC). We used Bombyx mori silk-fiber (Perhutani Pati, Central Java, Indonesia) and flowable composite (Charmfil flow, Denkist, Korea) in this study. The FRC samples were divided into 4 groups consisting of fiber volumes of 0%, 5%, 10% and 15% (n = 4). Tests of flexural strength were performed according to ISO 4049. The results were analyzed using one way ANOVA (p<0.05). The study showed that the means of the flexural strength (MPa) of Bombyx mori silk-fiber FRC for volume of 0%, 5%, 10% and 15% were 149.2 ± 5.5; 127.6 ± 3.8; 110.9 ± 3.5; 71.2 ± 4.2. One-way ANOVA test showed that the means of FRC flexural strength on the four groups’ silk-fiber Bombyx mori volumetric were significantly different (p<0.05). This study concluded that Bombyx mori silk-fiber volumetric influences the flexural strength of fiber- reinforced composite. An increase in Bombyx mori silk-fiber volume decreases the flexural strength of FRC because there is a small gap due to the weak interfacial bonds between dental flowable composite and Bombyx mori silk-silk-fiber

Corrosion Resistance of AISI 316L after Short Holding Time of High Temperature Gas Nitriding (HTGN)

Stainless steel AISI 316L is widely used as biomaterial due to its high corrosion resistance. However this property decreases in highly stressed and oxygen depleted environments. Several methods have been developing to increase the corrosion resistance such as low and high temperature gas nitriding. High temperature gas nitriding (HTGN) produces more depth effect than low temperature gas nitriding. Unfortunately HTGN for long holding time results on grain coarsening which reduce its tensile strength. The objective of this research is to determine the effect of HTGN at short holding time on the corrosion resistance, hardness and grain coarsening of AISI 316L. Specimens were made from as rolled 1 mm thickness AISI 316L plate. Before HTGN process, the specimens were rinsed using ultrasonic cleaner in acetone medium. HTGN process was conducted at temperature 1050oC, 1100oC and 1200oC for short period holding time i.e. 15 and 30 minutes. Micro hardness, microstructure and corrosion tests were conducted in the simulated body fluid (SBF) to evaluate the process. The results show that hardness and corrosion resistance were increased significantly after HTGN process. Moreover, hardness for holding time of 30 minutes was higher than 15 minutes, however the corrosion resistance were decreased. In addition HTGN process also results on grain coarsening at 30 minutes holding time, however for holding time 15 minutes and temperature 1050oC and 1100oC did not give significant grain coarsening. Therefore, the HTGN process parameters must be optimized for compromise between hardness and corrosion resistance. Keywords: high temperature gas nitriding, corrosion resistance, grain coarsening, AISI 316

Bacterial adhesion of Streptococcus mutans to cobalt chromium recast alloys

Cobalt chromium (CoCr) alloys are utilized to make dental prosthesis. Casting CoCr alloys is a common operation in dentistry laboratories due to its low cost. Casting surplus (metal remaining in the sprue and crucible former) is frequently reused by dental laboratories to reduce and recycle metal waste. However, the quality and safety of these recast alloys require further information. Microbial attachment to the surface of metal prostheses may affect its quality and safety. Biofilm formation on metal surface can cause biocorrosion and secondary infection. The effects of different proportions of recast Cobalt Chromium alloy on the bacterial adhesion are not clear. The purpose of this study was to investigate how recasting affects the Streptococcus mutans (S. mutans) adhesion. Twenty disk-shaped specimens (n= 20, allocated for 5 groups) were prepared from CoCr alloys (Remanium GM; Dentaurum) with different proportions (100% new alloy, 25% recast alloy, 50% recast alloy, 75% recast alloy, and 100% recast alloy). After the immersion of the specimens in bacterial suspension for 24 hours, the number of bacteria that adhere to the specimen’s surface was counted using Colony Forming Units. Data were analyzed with one-way ANOVA (α = 0.05). The bacterial adhesion was significantly affected by the recast alloys (p < 0.05). An increased proportion of CoCr recast alloys showed an increase in S. mutans adhesion to the specimen surface

Effect of Co-Cr alloy recasting on the fracture toughness

Frame denture generally uses Co-Cr alloy. However, alloy is expensive, so dental laboratories use residual sprue casting for recasting. The purpose of this study was to determine the effect of Co-Cr alloy recasting on fracture toughness. This was a laboratory experiment, with five sample groups, namely R0: 100% of new alloys; R1: 50% one-time recasting procedure and 50% new alloys, R2: 50% two-time recasting procedure and 50% new alloys, R3: 50% three-time recasting procedure and 50% new alloys, R4: 50% four-time recasting procedure and 50% new alloys. Fracture toughness was tested using a universal testing machine; the data were analyzed by One-Way Anova test and LSD (p>0.05). The results showed that the fracture toughness was 233.103 MPa-m1/2 in R4, and the highest was 242.435 MPa-m1/2 in R0. The results of the analysis by the LSD test on fracture toughness showed that there were no significant differences in R0 with R1 and R2, but there were significant differences between R0 with R3 and R4. There was a decrease after recasting in each group because of the missing elements of the Co-Cr alloy. The percentage of each element decreased due to oxidation and evaporation during heating. There was a change in the composition of the Co-Cr alloy in R3 and R4. There was a decrease in the fracture toughness. Variation in recasting frequency of Co-Cr alloy affected the fracture toughness. In each sample groups, the fracture toughness of Co-Cr alloy decreased after recasting

Orientation and Type of Non-dental Glass Fiber Towards The Flexural of Fiber Reinforced Composite

Introduction : Non-dental glass fiber can used as alternative dental glass fiber. Flexural strength to withstand masticatory loads that influenced by various factors, including the orientation and type of fiber used. Purpose : The purpose of this study was to see the effect of orientation and type of non-dental glass fiber on flexural strength. Method : The research method used FRC samples measuring 65 x 10 x 2,5 mm which were reinforced with non-dental glass fiber mats, roving, woven roving, and dental glass fiber roving. Non-dental glass fiber mats and woven roving was cut according to the length and width of the sample, while the non-dental glass fiber roving was weighed according to the weigh tof 4 sheets of dental glass fiber roving to meet the sample mold zone. Result : Glass fiber placed in the tension position in the sample mold. The flexural strength was tested using universal testing machine. This study indicate that the type of glass fiber doesn’t have a significant effect on the flexural strength of FRC with reinforced non dental glass fiber and dental glass fiber. Conclusion : The orientation of non-dental glass fiber roving as reinforcement of FRC has greater flexural strength than non-dental glass fiber with mats and woven roving orientation

Load displacement simulation of CP-Ti/UHMWPE hip implant

Hip implant made from titanium is special due to its lower modulus of elasticity to avoid stress shielding with the human bone. One type of load the material designed to withstand is a gradually increased compressive force which happened when the patient change his/her position from sitting to standing. This study examined the capability of a metal on polymer (MOP) implant made from commercially pure titanium (CP-Ti) and ultra-high molecular weight polyethylene (UHMWPE) loaded up to 3 kN according to ISO 14242 standard. Two CP-Ti/UHMWPE MOP models with femoral diameter of 22 mm and 32 mm were simulated with finite element. The results expressed in load displacement curves were validated with compressive load experimental tests. Both materials are capable to withstand the load. Simulation data are in good agreement with the experiments