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In recent years, numerous efforts have been made to synthesize new hole-transporting materials (HTMs) for perovskite solar cells (PSC) with the aim of replacing spiro-OMeTAD. However, to improve the conductivity and mobility of these materials, chemical additives are mostly used, which not only increase the cost but also reduce the stability and efficiency of perovskite solar cells in the long term due to the moisture sensitivity of perovskite crystals. Therefore, small organic molecules 2 and 6 were synthesized using cost-effective raw materials to improve the synthesis route, solubility, and morphology on the perovskite surface compared to spiro-OMeTAD for additive-free hole transport materials. The chemical properties, purity, and identification of these molecules were confirmed using electrochemical methods, UV-Vis spectroscopy, and NMR spectroscopy. In addition, thermal stability and robustness of new HTMs were measured and investigated by differential scanning calorimetric (DSC) and thermogravimetric analysis (TGA). Due to the donor-acceptor type π-system, the molecules used to increase the charge transfer mobility and thus reduce the use of chemical additives. The photovoltaic parameters of the solar cell made from HTMs 2 and 6 were determined by photovoltaic analysis, and the results showed that the performance of the device containing hole-transporting layer 6 was almost the same as of spiro-OMeTAD in additive-free conditions, with a current density of 14.68 mA/cm², an open-circuit voltage of 0.82 V, a fill factor of 0.65, and a power conversion efficiency of 7.88%. [ABSTRACT FROM AUTHOR]

One of the major business risks in the world-class manufacturing and services firms is the risk of imbalance between supply and demand. To respond to fluctuations in demand, changing the capacity is an expensive strategy that some of organizations adopt it. Developing in capacity in times of increasing the demand, while requiring expenditures can be caused by a decrease in demand leads to stagnant investment and capacity will be unusable. Reducing in capacity when demand decline, requires the sale of assets and the increase in demand will lead to lost sales costs. To face to this challenge, Mix production flexibility as concept of possibility to produce of multi production in a same facility is a cost-effective solution that can absorb imbalance risk between supply and demand. In this paper, managing of flexibility with cost-effective solutions in the world-class manufacturing firms studied and a mathematical model is proposed for this purpose. As a case study, production flexibility in SAIPA group analysis and using the proposed mathematical model and simulation software, solutions to increase manufacturing flexibility in SAIPA group recommended.

Background: Routine Para clinic evaluation of preoperative patients tends to cause unnecessary costs, extra risk to the patients, inefficient operating room schedules and extra medico legal risk. Furthermore, it seldom affects clinician's preoperative evaluation and decision making process for healthy patients. Numerous studies have shown that about 60% of these will not be performed if they are ordered according to recognizable indications based on history and physical examinations unfortunately the ‘indication based’ method can not replace to “routine” method due to difficulty and complexity to performing. Materials and Methods: We reviewed records of 1700 patients on a retrospective descriptive study in Sina Hospital from September 2000 to the end of September 2001. These patients had undergone general surgical procedures and were categorized as American society of anesthesiologists classification I or II. Results of complete blood count, fasting blood sugar, blood urea nitrogen, serum creatinin, sodium, potassium, chest X-ray, electrocardiogram and urinalysis were compared between patients under 40 years of age (n= 894) and patients aged 40 and over (n= 806). Results: Among 4935 tests performed in patients under 40 years of age, only 1004 (20.3%) were indicated, and treatment plan was not altered due to the results of routine tests in any case. In the other group, patients aged 40 and over, 6300 tests were performed, from which 3361 (53.3%) were indicated and treatment plans of 5 patients were influenced by the results of routine tests. Conclusion: Routine preoperative Para clinical tests is not cost effective method, otherwise the “indication based” also is difficult and complex method. We offer routine preoperative Para clinical tests only in patients over 40 years to combine ease of “routine” with a great reduction in medical costs and no adverse affect to patient care.