Evaluation of flotation technology for the trona industry

Trona ore consists mainly of trona, sodium sesquicarbonate dihydrate (Na₂CO₃·NaHCO₃·2H₂O), including minor undesirable insoluble materials. With the present industrial practice, there is no particle separation process to remove these insoluble minerals prior to thermochemical processing. In this current research appropriate conditions for trona flotation technology were established from exploratory bench-scale experiments, and the conditions obtained from the bench-scale experiments were also applied to pilot scale flotation tests. In this regard various process variables such as amine dosage, flotation percent solids, amine to oil ratio, pH of amine solution, collector structure, brine composition, feed particle size, etc. were studied to establish the preferred conditions and operating variables for pilot-plant testing. Additional information regarding the mineralogy of the system and collector characteristics is also reported to provide further analysis and explanation.     

Simultaneous measurement of velocity and length of moving surfaces by a speckle velocimeter with two self-mixing laser diodes

A novel laser speckle velocimeter with two self-mixing laser diodes (SM-LD's) for velocity and length measurements of moving surfaces is reported. The mean frequency of the speckle signal obtained in the measurement system depends on the surface path illuminated by the SM-LD. This behavior of the speckle signal in the SM-LD's is exploited to detect the front and the end edges of a target surface by sampling continuously the number of intensity changes in a speckle signal waveform. Once the edges are determined, the velocity and the length of the surface are calculated easily. The error for length and velocity measurements of a target with a homogeneous rough plane surface of 60-mm length, moving at a velocity of 200 mm/s, can be as low as 2.1% and 1.75%, respectively.     

Improvement of dissolution properties of furosemide by complexation with beta-cyclodextrin

The purpose of this study was to increase the solubility of furosemide (FR) with inclusion compound of beta-cyclodextrin (beta-CD). The interaction between FR and beta-CD in solution was studied by the solubility method. The phase solubility studies reveal a Bs-type diagram with an inclusion complex of 1:1 molar ratio and a stability constant of 823.5 M(-1). The solid complexes of FR with beta-CD were prepared by using freeze-drying, kneading, and co-precipitation methods. In addition, the physical mixture was prepared for comparison. Inclusion complexation was confirmed by the results from the studies of x-ray diffraction, differential scanning calorimetry, and infrared spectroscopy. The rates of release of the active material from the resulting complexes were determined from dissolution studies using the flow-through cell method. The dissolution rate of FR was significantly enhanced by inclusion of the beta-CD in the formulations. The rate of release of the active material was found to be dependent on the preparation method of the complexes, and the drug prepared by the kneading method was shown to have the fastest dissolution profile compared to the other methods used in this study.     

The usefulness of intra-operative endoscopy in Peutz-Jeghers syndrome: a case report

The Peutz-Jeghers syndrome is an autosomal dominant inherited disease manifested by a combination of mucocutaneous pigmentation and gastrointestinal hamartomatous polyps that usually cause intussusception and intestinal hemorrhage. We report a case in which the patient has been followed-up on for 14 years and who underwent surgical and endoscopic polyp removal several times as well as one intestinal resection. This time, with the use of combined surgery and perioperative endoscopy, 27 polyps were removed, performing only 3 enterotomies. This is the highest number in one session to be reported in the literature. The usefulness of this technique is providing a "clean small intestine" that allows the patient a longer time interval between laparotomies and reduces the complications associated with multiple laparotomies and resections.     

Compliance, quality of life, and contributing factors in renal transplantation waiting list patients

Poor patient compliance is common during dialysis therapy. We aimed to study incidence of noncompliance, contributing factors, and effects on quality of life (QOL) among cadaveric renal transplantation waiting list patients. We included 86 renal transplantation waiting list patients (56M/30F). Dialysis duration, previous renal transplantation history, comorbid conditions, interdialytic weight gain, predialysis BUN, creatinine, potassium, and phosphate were recorded. Noncompliance criteria were skipping >1 dialysis session or shortening a dialysis session>10 min in 1 month, interdialytic weight gain>5.7% of body weight, predialysis serum potassium >6 mEq/L, and phosphate level >7.5 mg/dl. There were 49 noncompliant (age: 46.8 ± 21.8 years, HD duration: 83.9 ± 48.7 months) and 37 compliant (age: 42.8 ± 12.1 years, HD duration: 96.5 ± 45.2 months) patients. QOL was evaluated by short form 36 and depression levels by Beck Depression Inventory. Previous renal transplantation was present in 24.4% and comorbid diseases in 31.3% of all patients. In depressed patients, 77.8% had comorbid diseases. No difference was found between the groups considering age, gender, dialysis duration, previous transplantation history, and comorbid diseases (p > 0.05). Noncompliant patients had lower QOL (p < 0.04). Noncompliant patients had higher degree of depression (p = 0.01). QOL and Beck scores were negatively correlated (p = 0.001, r = −0.561). Noncompliance to diet and dialysis therapy is associated with depression, which further decreases QOL in renal transplantation waiting list patients. Early diagnosis of depression, is possible by monitoring noncompliance, and therapeutic intervention may benefit during the transplantation‐waiting period.     

Thermal Management of On-Chip Caches Through Power Density Minimization

Various architectural power reduction techniques have been proposed for on-chip caches in the last decade. In this paper, we first show that these power reduction techniques can be suboptimal when thermal effects are considered. Then, we propose a thermal-aware cache power-down technique that minimizes the power density of the active parts by turning off alternating rows of memory cells instead of entire banks. The decrease in the power density lowers the temperature, which then exponentially reduces the leakage. Thus, leakage power of the active parts is reduced in addition to the power eliminated from the parts that are turned off. Simulations based on SPEC2000, NetBench, and MediaBench applications in a 70-nm technology show that the proposed thermal-aware architecture can reduce the total energy consumption by 53% compared to a conventional cache, and 14% compared to a cache architecture with thermal-unaware power reduction scheme. Second, we show a block permutation scheme that can be used during the design of the caches to maximize the distance between blocks with consecutive addresses. Because of spatial locality, blocks with consecutive addresses are likely to be accessed within a short time interval. By maximizing the distance between such blocks, we minimize the power density of the hot spots in the cache, and hence reduce the peak temperature. This, in return, results in an average leakage power reduction of 8.7% compared to a conventional cache without affecting the dynamic power and the latency. Overall, both of our architectures add no extra run-time penalty compared to the thermal-unaware power reduction schemes, yet they result in a significant reduction in the total energy consumption of a cache     

Structure and durability evaluation of YSZ + Al2O3 composite TBCs with APS and HVOF bond coats under thermal cycling conditions

Plasma sprayed thermal barrier coatings (TBCs) are applied to gas turbine components for providing thermal insulation and oxidation resistance. The TBC systems currently in use on superalloy substates typically consists of a metallic MCrAlY based bond coat and an insulating Y₂O₃ partially stabilized ZrO₂ as a ceramic top coat (ZrO₂ 7–8 wt.% Y₂O₃). The oxidation of bond coat underlying yttria stabilized zirconia (YSZ) is a significant factor in controlling the failure of TBCs. The oxidation of bond coat induces to the formation of a thermally grown oxide (TGO) layer at the bond coat/YSZ interface. The thickening of the TGO layer increases the stresses and leads to the spallation of TBCs. If the TGO were composed of a continuous scale of Al₂O₃, it would act as a diffusion barrier to suppress the formation of other detrimental mixed oxides during the extended thermal exposure in service, thus helping to protect the substrate from further oxidation and improving the durability. The TBC layers are usually coated onto the superalloy substrate using the APS (Atmospheric plasma spray) process because of economic and practical considerations. As well as, HVOF (High velocity oxygen fuel) bond coat provides a good microstructure and better adhesion compared with the APS process. Therefore, there is a need to understand the cycling oxidation characteristic and failure mode in TBC systems having bond coat prepared using different processes. In the present investigation, the growth of TGO layers was studied to evaluate the cyclic oxidation behavior of YSZ/Al₂O₃ composite TBC systems with APS-NiCrAlY and HVOF-NiCrAlY bond coats. Interface morphology is significantly effective factor in occurrence of the oxide layer. Oxide layer thickening rate is slower in APS bond coated TBCs than HVOF bond coated systems under thermal cycle conditions at 1200 °C. The YSZ/Al₂O₃ particle composite systems with APS bond coat have a higher thermal cycle life time than with the HVOF bond coating.     

A new conducting polymer of 2,5-bis(2-thienyl)-1H-(pyrrole) (SNS) containing carbazole subunit: Electrochemical, optical and electrochromic properties

We report here the synthesis of a new electroactive monomer 3,6-di-tert-butyl-[4-(2,5-di-2-thienyl-1H-pyrrol-1-yl)phenyl]-9H-carbazole in five steps and polymerization of this monomer by two different procceses: Kumada Coupling and electro-oxidative. The product obtained by chemical polymerization exhibits a high thermal stability and narrow molecular weight distribution. While, in the UV–vis absorption spectrum of monomer the absorption peaks appear at 338 nm, the chemically synthesized polymer absorbs at 428 nm with 90 nm red shift. Cyclic voltammogram of monomer shows two separate oxidation processes which reflect the first oxidation at +0.84 V and a second one at +1.43 V. When the polymeric film prepared by electrochemical process was subjected to a repeated cyclic scan between −0.2 V and +1.0 V, it switches among three different colors (orange, green and blue). The oxidation and reduction response times were calculated as 2.0 s for this polymer film and exhibits high redox stability. The results anticipate that this kind of polymers can be used for designing electrochromics based on the use of one molecule for the generation of three basic colors (RGB).     

A reactive power control relay design with a new approach

In this study, the design and implementation of a mixed-signal microcontroller based reactive power control relay that is superior to existing reactive power control relays is presented. This device measures the fundamental reactive power of the system and determines the switching pattern of the capacitor banks which brings the measured fundamental reactive power to the desired value. During measurement, it yields minimal computational load for the fundamental reactive power measurement by employing the Goertzel algorithm instead of the fast Fourier transform (FFT). Consequently, measurement accuracy can be increased without increasing the time required for the FFT-based power measurement by a running average using the last five measured values of the fundamental reactive power. Possible mechanical and electrical failures in capacitor banks are detected by using a simple feedback loop and the user is warned. It has all the other classical features such as P, Q, I, V, and power factor measurement, harmonic analysis, and failure warning signals that a relay should possess.     

Prevalence of juvenile chronic arthritis and familial Mediterranean fever in Turkey: a field study

OBJECTIVE: To investigate the prevalence of juvenile chronic arthritis (JCA), familial Mediterranean fever (FMF), and Beh?et's disease in Turkish children through a field survey. METHODS: The field survey was based on cluster centering with 2 level strata. A total of 46,813 children were screened. For the diagnosis of chronic arthritis and Beh?et's previously suggested criteria were used. We have developed criteria for the diagnosis of probable FMF. Children previously diagnosed to have these diseases were also defined and included. RESULTS: JCA was found in 6.4/10,000. 2.8/10,000 children were previously diagnosed as FMF (minimum phenotype frequency). Together with the probable diagnosis of FMF, the prevalence increased to 9.3/10,000. The findings were also compared with those of our center. None of the 46,813 children had Beh?et's disease. CONCLUSION: The prevalence of chronic arthritis is similar to the other childhood populations reported. However, FMF has a very high prevalence.