Perendaman Serat Batang Aren dengan NaOH sebagai Substrat Hidroponik Cabai Merah Besar

NaOH treatment is expected to can increased fiber tensile strength, therefore it is to become stronger and durable as substrate on hydroponic. This research aimed to study the growth and yield responses of chili, also fiber characteristic due to NaOH soaking treatment. This research was conducted on December 2018 to July 2019 at Greenhouse B and Laboratory of Plant Physiology and Biotechnology, Faculty of Agriculture, Universitas Sebelas Maret. This method used was Completely Randomized Design (CRD) that consisted of 2 factors and 3 replications. The first factor was NaOH concentration which consists 6 levels; 0%, 1%, 2%, 3%, 4% and 5%. The second factor was soaking duration which consists 4 levels; 0, 2, 4 and 8 hours. The results showed that NaOH treatment increased pH, bulk density, particle density and water holding capacity, however it is decreased macro pores on fiber. Treatment of 5% NaOH with 2 hours soaking duration decreased percent of fiber decomposed. Arenga wood fiber soaked on 2 hours duration increased root length. NaOH treatment decreased the number of fruits, weight fruit and weight of dried plant biomass, however treatment of 5% NaOH increased vitamin C content on fruit.

Comparison of prior exposure tensile damage and fracture of two-dimensional C/SiC and SiC/SiC fiber-reinforced ceramic-matrix composites

In this paper, a micromechanical constitutive model for prior exposure tensile damage and fracture of fiber-reinforced ceramic-matrix composites is developed considering the multiple damage mechanisms of matrix multicracking, interface debonding and oxidation, and fiber fracture. The relationships between prior exposure temperature, duration time, interface debonding fraction, broken fiber fraction, tensile strength, and fracture strain of C/SiC and SiC/SiC composites are established. The experimental prior exposure tensile damage evolution and final fracture of two-dimensional (2D) C/SiC and SiC/SiC composites are predicted for different temperatures and duration times. The comparison analysis of prior exposure composite tensile strength, fracture strain, interface debonding fraction, and broken fiber fraction between 2D C/SiC and SiC/SiC composites is investigated. The effects of constituent properties and temperature on prior exposure tensile damage and fracture of 2D C/SiC and SiC/SiC composites are discussed. For 2D C/SiC and SiC/SiC composites under prior exposure at 1300℃, the fracture strain decreased with fiber volume, interface shear stress, and prior exposure temperature, and increased with fiber characteristic strength; the tensile strength increased with fiber volume and fiber characteristic strength, and decreased with prior exposure temperature; the interface debonding fraction decreased with fiber volume, and increased with prior exposure temperature; and the fiber broken fraction decreased with fiber volume and fiber characteristic strength, and increased with prior exposure temperature.

Mixture Proportion Design Method of Steel Fiber Reinforced Recycled Coarse Aggregate Concrete

Steel fiber reinforced recycled coarse aggregate concrete (SFRCAC) is an impact minimisation building material. Mixture proportion design method of SFRCAC is developed in this paper to obtain concrete with target strength and workability, which can be used in structural members. Four key parameters of mixture proportioning, steel fiber content, water-cement ratio, water content and sand ratio are discussed through the mixture design tests. The formula for calculating the four key parameters of mixture proportions for SFRCAC are established through the statistical analysis of test results, which mainly consider the influences of recycled coarse aggregate (RCA) replacement ratio and steel fiber characteristic coefficient. The detailed procedure by using the new mixture proportion design method is illustrated with examples. The formulas established have the simple form, reflect the properties of RCA and steel fibers, enhance the mixture proportion design accuracy, and provide the reference for the mix proportion design of SFRCAC.

EVALUASI EFISIENSI ENERGI PENGERING MULTISILINDER PADA MESIN KERTAS UNTUK PRODUKSI KERTAS TULIS-CETAK GRAMATUR RENDAH

Paper machine has been designed for special purposes in accordance with the fiber characteristic used as the raw material, fiber development needed, and the fiber network developed so that the incremental water content reduction in the paper web from the inlet point of cylindrical dryer up to the outlet point of cylindrical dryer optimum. In industrial application, the paper machine designed for basis weight 60 gsm and virgin pulp as the raw material is often used for 45 gsm productions with virgin and recycled fiber as the raw material because of the paper demand. In this research the cylindrical dryer performance was observed when used for 45 gsm writing and printing paper production and their ability to dry the paper up to the design speed was simulated. Hopefully the result will able to give a contribution for energy efficiency so that the reduction of contribution margin can be anticipated.Keywords: cylindrical dryer, designed speed, energy efficiency, contribution margin. ABSTRAK Mesin kertas telah dirancang sesuai peruntukannya khususnya menyesuaikan dengan karakteristik serat yang digunakan sebagai bahan baku, pengembangan serat yang diinginkan dan jaringan serat yang terbentuk. Hal ini agar pengurangan kadar air yang terjadi secara bertahap dari pengering silinder ujung awal sampai ujung akhir dapat berjalan optimal. Dalam aplikasi industri sering dilakukan penyimpangan seperti mesin kertas yang dirancang untuk untuk memproduksi kertas tulis cetak 60 gsm bahan baku virgin digunakan untuk memproduksi kertas tulis cetak 45 gsm berbahan baku virgin maupun kertas daur-ulang berdasarkan permintaan pasar. Dalam penelitian ini diamati kajian kinerja pengering silinder mesin kertas saat pengeringan produk kertas tulis cetak 45 gsm dan simulasi kemampuan pengeringan pengering silinder tersebut sampai batas kecepatan rancangan mesin kertas. Hasil diharapkan dapat memberikan kontribusi terhadap efisiensi energi, sehingga langkah antisipasi terhadap kemungkinan penurunan kontribusi keuntungan dapat dilakukan.Kata kunci: pengering silinder, kecepatan rancangan, efisiensi energi, kontribusi keuntungan

Responses of auditory nerve fibers of the unanesthetized decerebrate cat to click pairs as simulated echoes

1. To elucidate the peripheral contribution to "echo" processing in the auditory system, we examined the characteristics of auditory nerve responses to click-pair stimuli in unanesthetized, decerebrate cats. We used equilevel click pairs at peak levels of 45, 65, and 85 dB SPL re 20 microPa. The interclick intervals ranged from 1 to 32 ms. This study reports results from 78 auditory nerve fibers in 7 cats. The fibers were divided into 2 groups: 33 low- and 45 high-spontaneous rate (SR), with SRs less than and > or = 20 spikes/s, respectively. A method was introduced to quantify the second-click response, and its recovery was examined as a function of the interclick interval. 2. In general, auditory nerve fibers showed a gradual recovery of the second-click response as interclick interval was increased. Noticeable differences in the second-click response recovery functions emerged among fiber populations that were related to the SR. Low-SR fibers showed little change in the recovery functions of the second-click response as the click level was increased from 45 to 85 dB SPL. In contrast, high-SR fibers showed slower recoveries with increasing click level from 45 to 85 dB SPL. At 45 and 65 dB SPL, the recovery functions of the two SR groups were similar. At 85 dB SPL, high-SR fibers exhibited slower recovery than low-SR fibers, regardless of fiber characteristic frequency. The interclick intervals at 50% second-click response ranged from 1 to 6 ms (mean, 1.4 ms) among low-SR fibers. The interclick intervals at 50% second-click response for high-SR fibers, whereas similar to those for the low-SR fibers at 45 and 65 dB SPL, ranged from 2 to 16 ms (mean, 3 ms) for high-SR fibers, at 85 dB SPL. 3. We also examined auditory nerve compound action potentials (CAPs) evoked by click-pair stimuli for various interclick intervals and click levels. With increasing interclick interval, the amplitude of the second-click CAP increased, and with increasing level, the second-click CAP showed slower recovery. At 45 dB SPL, the recovery functions of the second-click CAP were similar to those of the high- and low-SR fibers. At higher levels, the CAP exhibited lower second-click response values than both high- and low-SR fiber populations for interclick intervals < 4-8 ms. At 85 dB SPL, as interclick interval increased, between 8 and 16 ms, the CAP second-click response converged with that of the high-SR fibers, and by 32 ms, the second-click response values were similar for the CAP, high- and low-SR fibers. 4. The present results are consistent with those of forward masking studies at the level of the auditory nerve in that both demonstrate a short-term reduction of the neural responses. However, the two results differ in that we observed that high-SR fibers exhibited slower recovery than low-SR fibers in response to click-pair stimuli, opposite of the trend observed in the forward masking studies of responses to pure-tone bursts. 5. The present results on auditory nerve fiber responses to click-pair stimuli provide a reference for comparison with responses of central auditory neurons to similar stimuli. This information should serve to elucidate the peripheral contribution to the processing of echoes in the auditory system.