Behavior of decomposition of rifampicin in the presence of isoniazid in the pH range 1-3

The extent of decomposition of rifampicin in the presence of isoniazid was determined in the pH range 1-3 at 37°C in 50 min, the mean stomach residence time. With increase in pH, the degradation initially increased from pH 1 to 2 and then decreased, resulting in a bell-shaped pH-decomposition profile. This showed that rifampicin degraded in the presence of isoniazid to a higher extent at pH 2, the maximum pH in the fasting condition, under which antituberculosis fixed-dose combination (FDC) products are administered. At this pH and in 50 min, rifampicin decomposed by ~ 34%, while the fall of isoniazid was 10%. The extent of decomposition for the two drugs was also determined in marketed formulations, and the values ranged between 13-35% and 4-11%, respectively. The extents of decomposition at stomach residence times of 15 min and 3 h were 11.94% and 62.57%, respectively, for rifampicin and 4.78% and 11.12%, respectively, for isoniazid. The results show that quite an extensive loss of rifampicin and isoniazid can occur as a result of interaction between them in fasting pH conditions. This emphasizes that antituberculosis FDC formulations, which contain both drugs, should be designed in a manner that the interaction of the two drugs is prevented when the formulations are administered on an empty stomach.     

基于VXI总线高速数字测试模块的设计

文章介绍了基于VXI总线高速数字测试模块的工作原理和技术指标。讨论了模块的设计思想及数据传输方式。该模块通用性和扩展性强,具有高速数据传输和实时故障诊断功能。     

基于共现词查询的主题爬虫研究

通过建立一个共现词库改进主题模型,以提高下载网页的主题相关度及质量,并且能描述其语境的上下文,揣测用户意图,调节检索结果排序。在此基础上设计并实现一个FDC主题爬虫系统,该系统采用改进的主题敏感FDC-PageRank算法来计算网页优先级。实验表明其效果良好。     

Behavior of Decomposition of Rifampicin in the Presence of Isoniazid in the pH Range 1–3

Abstract

The extent of decomposition of rifampicin in the presence of isoniazid was determined in the pH range 1–3 at 37°C in 50 min, the mean stomach residence time. With increase in pH, the degradation initially increased from pH 1 to 2 and then decreased, resulting in a bell-shaped pH-decomposition profile. This showed that rifampicin degraded in the presence of isoniazid to a higher extent at pH 2, the maximum pH in the fasting condition, under which antituberculosis fixed-dose combination (FDC) products are administered. At this pH and in 50 min, rifampicin decomposed by ? 34%, while the fall of isoniazid was 10%. The extent of decomposition for the two drugs was also determined in marketed formulations, and the values ranged between 13–35% and 4–11%, respectively. The extents of decomposition at stomach residence times of 15 min and 3 h were 11.94% and 62.57%, respectively, for rifampicin and 4.78% and 11.12%, respectively, for isoniazid. The results show that quite an extensive loss of rifampicin and isoniazid can occur as a result of interaction between them in fasting pH conditions. This emphasizes that antituberculosis FDC formulations, which contain both drugs, should be designed in a manner that the interaction of the two drugs is prevented when the formulations are administered on an empty stomach.     

基于K最近邻算法的手势识别装置

笔者基于TI公司传感芯片FDC2214设计制作一个手势识别装置,原理是利用FDC2214对手势信号进行采集,然后发送给STM32F407ZGT6单片机进行处理,利用K最近邻算法实现对猜拳游戏和划拳游戏的判决。通过测试,装置能较好地实现课题提出的各项要求,笔者在后期会进一步优化和完善该装置,以期达到更理想的效果。     

A constant loop bandwidth in delta sigma fractional-N PLL frequency synthesizer with phase noise cancellation

This work presents the design of a new and unique design technique of constant loop bandwidth and phase-noise cancellation in a wideband ΔΣ fractional-N PLL frequency synthesizer. Phase noise performance of the proposed ΔΣ fractional-N PLL frequency synthesizer has been verified using CppSim simulator with the help of transistor level simulation results in Cadence SpecctreRF. Transient response of the proposed ΔΣ fractional-N PLL has been verified in transistor level simulation using Cadence SpectreRF in 0.13 μm standard CMOS process. The proposed phase-noise cancellation and constant loop bandwidth in wideband ΔΣ fractional-N PLL reduces the out of band phase noise by 18 dBc/Hz at 2 MHz offset frequency for a closed loop bandwidth of 1 MHz, when I_CP,max is equal to 2.6 mA. PLL locking time has been reduced with phase-noise cancellation and a constant loop bandwidth calibration circuits using the proposed CP unit current cell for the mismatch compensated PFD/DAC in wideband ΔΣ fractional-N PLL frequency synthesizer. Optimum phase noise performance can be achieved with the help of proposed design technique. Proposed ΔΣ fractional-N PLL frequency synthesizer is locked within 14.0 μs with an automatic frequency control circuit of the LC VCO and a constant loop bandwidth calibration circuit through the use of proposed CP unit current cell for the mismatch compensated PFD/DAC for the phase-noise cancellation in worst case condition of K_VFC = 10 and K_LBC = 150. Our new design technique can be extensively integrated for wideband fractional-N PLL for new type of wireless communication paradigm using the thinnest channel subharmonic transistor and low power devices, and it has the potential to open a new era of fractional-N PLLs for wideband application.     

An explanation for the physical instability of a marketed fixed dose combination (FDC) formulation containing isoniazid and ethambutol and proposed solutions

An investigation was carried out to explore the possible reason for the physical instability of a marketed strip packaged anti-TB fixed dose combination (FDC) tablet containing 300 mg of isoniazid (H) and 800 mg of ethambutol hydrochloride (E). The instability was in the form of distribution of white powder inside the strip pockets. High-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS-MS) studies confirmed that both H and E were present in the powder. The same was also confirmed through Fourier-transform infrared (FTIR) spectroscopy, which also indicated absence of interaction between the two drugs. No sublimation of the drugs was observed up to 110°C, indicating that the observed instability was not due to this reason. Subsequently, attention was paid to the possibility of moisture gain by the tablets through defective packaging (which was established) due to hygroscopicity of E. To understand the phenomenon further, pure drugs and their mixtures were stored under accelerated conditions of temperature and humidity [40°C/75% relative humidity (RH)] and both increase in weight and physical changes were recorded periodically. The mixtures gained moisture at a higher rate than pure E and those with higher content of E became liquid, which on withdrawal from the chambers, became crystallized. The drug mixture containing H:E at a ratio of 30:70 w/w, which was similar to the ratio of the drugs in the tablets (27:73 w/w), crystallized fastest, indicating formation of a rapid crystallizing saturated system at this ratio of the drugs. It is postulated that the problem of instability arises because of the formation of a saturated layer of drugs upon moisture gain through the defective packaging material and drying of this layer with time. The study suggests that barrier packaging free from defects and alternatively (or in combination) film coating of the tablets with water-resistant polymers are essential for this formulation.     

手势识别装置的设计与实现

手势识别已成为人机交互技术的关键之一。笔者基于传感芯片FDC2214设计制作了手势识别装置和STM32F103C8T6微控制器控制系统,能够通过JC22-V05串口显示器显示测试结果。考虑到手势的大小,对石头剪刀布和12345手势进行了识别实验,结果表明本算法可行。     

The brave new world of FDA nutrition regulation — some thoughts about current trends and long‐term effects∗

This article reviews long‐term trends at the U.S. Food and Drug Administration (FDA) concerning regulation of nutrition, and considers how these trends may affect products of the food industry in the decades ahead. Among the topics discussed are the FDA's rules concerning the provision of basic, standard format nutrition information (“nutrition labeling”) on food products. These rules have changed dramatically over the past 50 years from a period when no information was required to a period when information was required only if a nutrient claim was made or if a nutrient was added to the product to the new FDA regulations that become effective in 1994, which require standardized nutrition labeling on most food products in interstate commerce.

There have also been important shifts in the procedures concerning government regulation of nutrition‐related labeling. In general, previously a food company was free to provide truthful and nonmisleading labeling claims about the nutrition content of a food product, leaving it to FDA to police the market and to take regulatory action against any labeling that the agency deemed either to be false or misleading or to constitute an unauthorized drug claim. In contrast, under new FDA regulations, it will become automatically illegal to use any “health claim” or “nutrient content claim” in food labeling unless the claim has been approved in advance by an FDA regulation.

The author notes that these and other developments reveal, on the one hand, a trend toward requiring more nutrition information on food labels, but, on the other hand, a countervailing trend toward requiring government approval for the making of new nutrition‐related statements and placing greater burdens on industry to justify new types of nutrition‐related statements. Additional trends include the increased pressures on companies to formulate foods to be more healthful and a trend toward giving the FDA more power over the industry.

The article concludes with comments about additional regulatory requirements to which the long‐term trends might lead in future decades.     

Mechanical testing of hydroxyapatite filaments for tissue scaffolds preparation by fused deposition of ceramics

Composite filaments with diameter ∼1.75 mm suitable for fused deposition of ceramics were prepared from commercial hydroxyapatite powders (HAp-0, d₅₀ ≤ 35 μm and HAp-1, d₅₀ ≤ 16 μm) and thermoplastic polymer - polyvinyl alcohol. The filament printability in FDC applicable as specific bone-part replacements, is connected to its mechanical strength and slenderness ratio affecting the resistance to buckling. The HAp content in prepared composite filaments was at the level of ∼ 50 % and their mechanical properties were compared to commercial filament based on polylactic acid and ∼ 27 % of gypsite used as inorganic filler. The tensile strength of laboratory prepared filaments was about 3 times lower than strength found for commercial filament. The critical buckling pressure calculated from Euler buckling analysis using measured intrinsic Young´s modulus revealed underestimated critical pressure values ∼ 2.5–5.0 times if compared to values of maximal filament compressive pressure loads simulating buckling.