您搜索了: high flow auxiliary hydraulics (combined) (英语 - 波斯语)

some doctors prefer staying with invasive mechanical ventilation when available because this technique limits the spread of aerosol particles compared to a high flow nasal cannula.severe cases are most common in older adults (those older than 60 years, and especially those older than 80 years).
برخی پزشکان ترجیح می‌دهند که در صورت وجود، از هوارسانی مکانیکی تهاجمی استفاده کنند زیرا این روش میزان پراکنش ذرات ریز را در مقایسه با کانولای بینی جریان-بالا محدود می‌کند. شیوع موارد شدید در سالخوردگان بیشتر است (افراد بالای 60 سال، و به‌ویژه افراد بالای 80 سال).

the concept of chromatography in expanded bed adsorption (eba) was first proposed in early 90s. the initial advantage of the idea was to be able to directly process particulate containing biological feedstocks for target products, while still maintaining sufficiently high separation efficiency that is usually enjoyed only by the traditional chromatography columns. eba could potentially replace several traditional unit operations combined, namely centrifugation, filtration, and capture chromatography. eba can significantly shorten the overall processing time, increase the overall yield, and save both capital investment and operating cost for many biological purification processes - figure 1. eba is different from the fluidized bed used in the traditional chemical industry. the media beads are only intended to be fluidized in their local area, instead of a full mixing stage as in a fluidized bed, to provide reasonably high separation efficiency (plate count). a typical eba operation involves the following steps: bed stabilization/equilibration, sample loading, washing, elution, regeneration and cleaning, and re-equilibration as shown in figure 2. the settled eba bed is first expanded by applying upward flow that is sufficiently fast to fluidize the media beads. particulate containing feedstock will be directly applied into the column after equilibration. the target proteins or smaller molecules will be binded to the eba absorbent while other contaminants such as nucleotide and lipids pass through. a wash will be applied using fresh buffer to remove the loosely bound contaminant molecules after the sample loading. elution step is usually run as a packed bed by lowering the top adaptor and applying downward flow. the target proteins or molecules that were binding on the adsorbent will be eluted from the column and collected. the column will then be cleaned/regenerated using stronger agents such as sodium hydroxide and re-equilibrated using the starting buffer for the next loading cycle. the early eba columns are susceptible to fouling and clogging in its distributor. the main drawbacks in eba process were hygienic issue and bed stability. the issues were associated with the distributor, which is a critical component in providing even flow distribution in eba technology. as some kind of high flow resistant components were necessary for distributing the flow, it turned out that it is difficult to clean the aggregates formed upstream of the high resistance component inside the distributor, which could happen as a result of aggregation of cells and biomass over time. aggregations of biomass and interactions between media and cell debris sometimes also causes bed stability and channeling problem. the first generation eba column did not see wide application mostly owing to the hygienic issue involved with the distributor and bed stability with difficult feedstock from cell lysis. the eba technology was further developed into its second generation that features a patented distributor with moving arms to distribute the flow toward the bottom of the column. the distribution concept is illustrated in figure 4. the second generation eba column has an open flow design in the distributor and a bypass on the top adaptor and therefore has no cleaning issues. the distributor leads to significant back mixing in the lower part of the column. there are concerns regarding media grinding, operation reliability, and maintenance cost. in addition, elution can only be done in expanded bed mode. the concentration factor of the process is therefore much lower than the traditional eba. the second generation eba column only had a dismal launch in the industry. in fact, some major players decided to stop manufacturing and marketing the product shortly after the second generation design was introduced to the market. while eba has obvious advantages, the challenges in developing eba process are the hygienic design of the flow paths, stability of the expanded bed, and maintaining even flow distribution (to achieve sufficient separation efficiency). a bed independent flow distributor with open cleanable flow paths is considered the critical challenge to make eba a robust technology. a traditional distributor relying on high resistance components (such as the perforated plate or a thick mesh in the first generation of design) does not meet the hygienic requirement as the upstream of the high resistance component will be subjected to fouling and clogging and will not be cleanable by the flow itself. aggregation formed in the bed and inside the distributor during the usually long time loading step cannot be effectively and reliably cleaned which is imperatively needed before elution starts. on the other side most of the open channel distributors will not be able to distribute the flow without making significant disturbance to the eba bed.
محاسبه عوامل نگهدارنده (rf) برای کروماتوگرافی لایه ای نازک پس از توسعه و مشاهده صفحه tlc ، نقطه شروع و جلوی حلال (سطح حلال که در هنگام خارج شدن صفحه از مخزن در حال توسعه به دست می آید) مشخص شده و تمام نقاط مشاهده شده در صفحه در مداد سرب چرخانده شده است. محل محاسبه هر نقطه در صفحه سپس با محاسبه یک عامل احتباس (rf) عددی نشان داده می شود. این با انجام اندازه گیری ها و محاسبات زیر انجام می شود: