Protection From Contamination by 211At, an Enigmatic but Promising Alpha Emitter

Purpose 211At, a promising alpha emitter, can easily volatilize and contaminate the environment. To safely manage this unique alpha emitter, we investigated the permeability of four types of plastic films and gloves against 211At and identified suitable materials to avoid contamination by 211At. Methods Four types of plastic films, polyethylene, polyvinylidene chloride, polyvinyl chloride, and a laminated film, and two types of rubber gloves, latex and nitrile, were examined. Small pieces of filter paper were covered with these materials, and a drop containing 100 kBq of 211At was placed on them. The radioactivity of pieces of filter paper under the materials was evaluated by measuring counts using a gamma counter and obtaining autoradiograms 3.5 h later. These experiments were also performed using 225Ac, 125I, 111In, 201Tl, and 99mTc. Results 211At solution easily penetrated polyethylene, polyvinyl chloride, and latex rubber. Similar results were obtained for 125I, while other radionuclides did not penetrate films or gloves. These results suggest that halogenic radionuclides under anionic conditions are likely to penetrate plastic films and rubber gloves. Conclusion Our evaluation revealed that, when 211At solution is used, the protection by polyvinylidene chloride, a laminated film, or nitrile rubber would be more effective than that by polyethylene, polyvinyl chloride, or latex rubber.

Respons produksi tanaman karet klon BPM 24 terhadap jenis dan konsentrasi stimulan etilen organik kulit pisang

AbstrakPuncak produksi tanaman karet klon BPM 24 dicapai pada tahun sadap ke-7 sampai 10, tetapi produksi menurun dengan cepat hingga mencapai titik terendah pada tahun sadap ke-15. Stimulan merupakan teknologi yang digunakan untuk meningkatkan produksi lateks. Penggunaan stimulan sintetik yang berlebih dapat menurunkan produksi sehingga perlu dicoba stimulant organik. Penelitian ini bertujuan untuk mengetahui respons produksi tanaman karet klon BPM 24 terhadap aplikasi stimulan organik kulit pisang. Penelitian dilaksanakan di Kebun Percobaan Balai Penelitian Karet Sembawa, Palembang, Sumatera Selatan dari September sampai November 2019. Metode percobaan menggunakan Rancangan Acak Kelompok dengan 11 perlakuan stimulan dan 5 ulangan. Pengamatan dilakukan terhadap produksi lama aliran lateks, volume lateks dan kadar karet kering. Hasil penelitian menunjukkan bahwa perlakuan stimulan organik kulit pisang Ambon dengan konsentrasi 200 g/L mampu meningkatkan lama aliran lateks, dan volume lateks, tetapi pemberian stimulan menurunkan kadar karet kering.Kata kunci : Stimulan Organik , kulit pisang, Lateks, karet Klon BPM 24 AbstractThe rubber tree production clone BPM 24 reaches its peak on 7th to 10th years of tapping incision. After that, the production declines rapidly to the lowest point at 15th year. Stimulant application is one of the technology to increase latex production. Excess application of synthetic stimulants can reduce production, so organic stimulants should be tried. The research intended to know the response of production of rubber tree (Hevea brasiliensis Muell. Arg) clone BPM 24 due to application of the organic ethylene stimulant made of banana peels. The research was conducted from September to November 2019, at Experimental Plantation of Rubber Research Institution, Sembawa, Palembang, South Sumatra. The method of this research was the experimental design that used Randomized Block Design with 11 treatment and three times replication. The observation made on latex flowing duration, latex volume, and dried latex content. The result showed that application of organic ethylene stimulant made of banana peels cv. Ambon on 200 g concentration could increase latex flowing duration and latex volume, but reduced dried latex content. Keywords: stimulant, banana peels, latex, rubber clone BPM 24.

Fractal analysis of concurrently prepared latex rubber casts of the bronchial and vascular systems of the human lung

Fractal geometry (FG) is a branch of mathematics that instructively characterizes structural complexity. Branched structures are ubiquitous in both the physical and the biological realms. Fractility has therefore been termed nature's design. The fractal properties of the bronchial (airway) system, the pulmonary artery and the pulmonary vein of the human lung generates large respiratory surface area that is crammed in the lung. Also, it permits the inhaled air to intimately approximate the pulmonary capillary blood across a very thin blood–gas barrier through which gas exchange to occur by diffusion. Here, the bronchial (airway) and vascular systems were simultaneously cast with latex rubber. After corrosion, the bronchial and vascular system casts were physically separated and cleared to expose the branches. The morphogenetic (Weibel's) ordering method was used to categorize the branches on which the diameters and the lengths, as well as the angles of bifurcation, were measured. The fractal dimensions ( D F ) were determined by plotting the total branch measurements against the mean branch diameters on double logarithmic coordinates (axes). The diameter-determined D F values were 2.714 for the bronchial system, 2.882 for the pulmonary artery and 2.334 for the pulmonary vein while the respective values from lengths were 3.098, 3.916 and 4.041. The diameters yielded D F values that were consistent with the properties of fractal structures (i.e. self-similarity and space-filling). The data obtained here compellingly suggest that the design of the bronchial system, the pulmonary artery and the pulmonary vein of the human lung functionally comply with the Hess–Murray law or ‘the principle of minimum work’.

Effect of Latex Rubber and Rubber Powder as an Admixture on Bending Strength of Cement Mortars

This paper reported the effect of latex rubber (LR) and rubber powder (RP) on the bending strength of cement mortars containing fly ash silica (FAS) prepared from sugarcane bagasse. The bending strengths of the cement mortars with the addition of LR and RP were compared. The study was conducted by adding 5-10 wt% of each admixture into cement mortar specimens and left in air atmosphere for 28 days before measuring their bending strength. At 5 wt.%, both LR or RP could significantly reinforce the bending strength of the mortar. The bending strength of cement mortars decreased when the proportion of the LR and RP were higher than 5 wt%. In addition, at 10 wt%, LR provided better bending strength than that of RP, i.e. the bending strength of mortar contained LR was 550 ksc, whereas that contained RP was 85 ksc. The bending strength of mortar with LP was much higher than that of the pure cement mortar (20 wt% FAS : 80 wt% cement) which was about 62 ksc. The low bending strength of the mortar with 10 wt% RP may be due to the decrease of Si-O-Si hybrid compounds which was inhibited by the hydroxyl group during the hydrolyzation process.

THE EFFECT OF LEATHER FIBERS ON VULCANIZATION BEHAVIOR OF NATURAL RUBBER

This paper shows the primary research results of the effect of the leather fibers on the vulcanization of natural rubber (NR). The fibers used in this research were prepared by grinding waste leather scraps of Vietnam shoe making company. Leather fibers (LFs) and natural latex rubber were mixed together at various rates by a stirring machine. The obtained composites of natural rubber containing leather fibers were dried at pleasant condition prior to the analysis. Vulcanization behavior of the samples was clarified using a moving die rheometer. The vulcanization temperature as 120 °C is found to be the appropriate temperature for the NR/LFs composite. The increasing of minimum and maximum torque with the increasing of leather fiber content shows the improving in stiffness of natural rubber with the presence of leather fibers. Regarding to curing curves, 40 wt% promises to be the optimal leather fiber content to reinforce natural rubber.

Endoscopic Endonasal Management of Recurrent Maxillary Mucoceles Using Biliary T-Tube Stenting

Mucoceles of the paranasal sinus can be managed endoscopically with an extremely low recurrence rate. Frontal sinus mucoceles can sometimes be prevented from closing and reforming by stenting, which to the best of our knowledge has not yet been reported in the maxillary sinus. We describe the cases of 5 patients—3 men and 2 women, aged 47 to 75 years (mean; 59.6)—with a recurrent and intractable maxillary sinus mucocele that was managed with biliary T-tube stenting. The indications for stenting included recurrent episodes of mucocele with or without a lateral location with a relatively thick bony wall. A latex rubber pediatric biliary T-tube was endoscopically inserted through a window opening into the marsupialized mucocele. The stent was removed 6 to 14 months postoperatively in 4 cases; in the other case, the stent remained adequately positioned for 35 months. None of the patients experienced signs or symptoms of recurrence. We conclude that a T-tube stent can be used successfully to maintain long-term patency in patients with a recurrent and intractable maxillary mucocele, with patency being maintained even after removal of the stent.