The challenge of enzyme cost in the production of lignocellulosic biofuels.

With the aim of understanding the contribution of enzymes to the cost of lignocellulosic biofuels, we constructed a techno-economic model for the production of fungal cellulases. We found that the cost of producing enzymes was much higher than that commonly assumed in the literature. For example, the cost contribution of enzymes to ethanol produced by the conversion of corn stover was found to be $0.68/gal if the sugars in the biomass could be converted at maximum theoretical yields, and $1.47/gal if the yields were based on saccharification and fermentation yields that have been previously reported in the scientific literature. We performed a sensitivity analysis to study the effect of feedstock prices and fermentation times on the cost contribution of enzymes to ethanol price. We conclude that a significant effort is still required to lower the contribution of enzymes to biofuel production costs.

Impact of source-separation of urine on treatment capacity, process design, and capital expenditure of a decentralised wastewater treatment plant.

In this study, the impact of urine diversion on the treatment capacity, treatment process, and capital costs of a decentralised wastewater treatment plant (WWTP) was simulated using BioWin. The data for simulation including for economic analysis were obtained from a real decentralised WWTP at Sydney. Simulation was conducted for two alternative process design scenarios of a WWTP: membrane bioreactor (MBR) without denitrification and anaerobic MBR in place of aerobic MBR and compared to existing process design. The simulation shows that with about 75% urine diversion (through source separation), the treatment capacity of the existing WWTP can be doubled although above 40% urine diversion, the impact appears less rapid. When the urine diversion exceeds 75%, it was found that the anoxic tank for biological denitrification becomes redundant and the current wastewater treatment process could be replaced with a simpler and much less aeration intensive membrane bioreactor (MBR) producing similar effluent quality with a 24% reduction in capital expenditure (footprint) cost. Anaerobic MBR can be a potential alternative to aerobic MBR although pre-treatment becomes essential before reverse osmosis treatment for water reuse applications. Sensitivity analysis has revealed that by operating the bioreactor at higher mixed liquor suspended solids concentrations (9 g/L instead of 5 g/L) could help increase the WWTP treatment capacity by about 3.5 times at 75% urine diversion. Hence, urine diversion (until nitrogen-limiting conditions occur above 75% urine diversion) can increase the treatment capacity of an existing WWTP and reduce the capital expenses due to reduced plant footprint.

Mobile dental units: leasing or buying? A dollar-cost analysis.

INTRODUCTION: The decision to acquire a mobile dental unit is based on a standard capital budgeting analysis. The next step is to determine whether to obtain the use of the mobile dental unit by borrowing and purchasing or by leasing. As a financing mechanism, leases are simply another way of borrowing money to pay for the asset. OBJECTIVE: To compare lease vs. debt as financial vehicles to acquiring a mobile dental unit. METHODS: An estimate for a new mobile unit was obtained. Lease and loan proposals from financial lenders were collected. A cost of capital rate was chosen for comparison. Cash flows associated with borrowing and leasing vs. buying were determined fortwo different scenarios: for profit (FP) vs. not-for-profit (NFP), at 5 years. A dollar-cost analysis was utilized to determine the option with the lowest capitalized value. RESULTS: There was a net advantage to buying vs. leasing for both for FP and NFP organizations. Due to tax advantages, owning and leasing were substantially less expensive for FP than for NFP. Slight decreases in the monthly lease payments would make leasing competitive to the buying approach. CONCLUSION: Exploring alternative financing vehicles may allow dental programs to expand their services through the acquisition of a mobile unit. Though programs generally own assets, it is the use of the asset which is important rather than the ownership. Dental programs can find leasing an attractive alternative by offering access to capital with cash-flow advantages.

Dentistry a la carte: in-office CAD/CAM technology.

This article examines the differences among four in-office computer-aided design/computer-aided manufacturing restorative technologies. Two acquisition media systems, 3M ESPE's Lava COS and Cadent's iTero, are compared and contrasted. Additionally, two acquisition and manufacturing media, Sirona's CEREC AC and D4D's E4D, are examined. Image acquisition techniques and cast fabrication methodologies are compared between Lava COS and iTero. In addition, image acquisition, cast fabrication, and restoration fabrication methodologies are discussed as related to CEREC AC and E4D. Strategies for computer-aided design/computer-aided manufacturing incorporation into practice are explored.

Implementation strategies for incorporating new technologies into the dental practice.

Staying ahead of the technology curve is an ongoing challenge for all dentists. Ignoring advancements in technology and the related improvements in diagnostics and delivery of care, as well as the impact technology may have on productivity in practice, is simply not an option for the modern clinician who aims to maintain a successful contemporary practice. This article delivers some insight into the challenges that arise when upgrades in technology and the related acquisition investment are considered.

CAD/CAM options in dental implant treatment planning.

Several software platforms are available that use computerized tomography files and proprietary 3-D reformatting to aid in diagnosis, plan implant location, and complete the surgical placement and restoration of dental implants. This article will review traditional versus computerized model of surgical planning, advantages and disadvantages of computer-aided design/computer-aided manufacturing planning, variability in treatment sequence, and a cost analysis of investment into this treatment modality.

Progressing the action plan in Scotland--an educational perspective.

In March 2005 the Scottish Executive Health Department published the 'Action plan for improving oral health and modernising NHS dental services in Scotland'. Six areas required major new educational input: pre-qualification education, workforce supply, career development, dental practice and team development, clinical effectiveness/quality improvement and support for the oral health strategy. Targets from the action plan that have been fully achieved include: 1) undergraduate student numbers have reached the target output of 135 per year; 2) vocational training numbers match graduate numbers; 3) a vocational training scheme for dental therapists has been developed and numbers of VT places will match the number of qualifying therapists; 4) a new strategy to support dental nurse training will allow an additional 200 dental nurse training places by 2007; and 5) a clinical effectiveness programme has developed a rolling programme of guidelines, the first one of which, on conscious sedation, was released in May. The dental action plan has provided Scotland with the best opportunity for modernising dental services since the NHS was established. This paper describes some of the educational developments that will ensure NHS dental services in Scotland are 'fit for the future' and 'delivering for health'.

Cost aspects of salt fluoridation.

The cost of salt fluoridation in a given country depends primarily on the number of salt factories and on the technical level available in the country. Equipment required may cost U.S. dollars 400,000 for large plants producing at least 20,000 tons/year providing salt for populations of several millions. Reliable batch mixers have been built locally for U.S. dollars 3000 to U.S. dollars 10,000, with one such mixer capable of producing 10 batches of one metric ton/day or 2000 to 3000 tons a year for a population of 350,000 to 500,000. Frequently 85-90% of the costs are devoted to infrastructure; in combination with salt iodization, the cost for fluoride equipment is 30-50% less. loIization is promoted by WHO, UNICEF, other international organizations and national aid agencies which can indirectly support salt fluoridation. With respect to running costs, the expense for the fluoride chemical is the major factor in small plants producing for example 6000 tons of salt, i. e U.S. dollars 0.015 to 0.03 per year and capita. The cost for personnel necessary for addition of fluoride and quality control is approximately U.S. dollars 0.008/capita/year in small plants and even less in large ones. With adequate implementation, salt fluoridation affords a cariostatic effectiveness equal to that of water fluoridation. When its cost is compared to that of water fluoridation, there may not be much difference regarding initial cost for equipment except in the case of small salt factories where local production of batch mixers may lower initial expenses substantially. Running costs for salt fluoridation are 10 to 100 times lower because the amount of fluoride chemical needed and its handling are up to 100 times less than with water fluoridation. In practice, the cost of salt fluoridation is often so low that many producers did not raise the price of fluoridated salt; this has been the case in Switzerland since 1955 and also in several countries in the Americas today.

Economics evaluation for on-site pyrolysis of kraft lignin to value-added chemicals.

This work is part of a series of investigations on pyrolysis of lignin. After obtaining the necessary information regarding the quantity and quality of the obtained products, a first step economics evaluation for converting lignin into chemicals was essential. To accomplish this aim, a pyrolysis plant with a 50t/d capacity was designed, and the total capital investment and operating costs were estimated. Next, the minimal selling price of the obtained dry oil was calculated and the effect of crucial variables on the estimated price was examined. The key result indicates the estimated selling price would not compete with the price of the chemicals that are fossil fuel based, which is primarily due to the high cost of the feedstock. To overcome this challenge, different scenarios for reducing the selling price of the obtained oil, which consequently is helping by taking a place among the fossil fuel based chemicals, were discussed.

Resource productivity and returns to scale in school-based mouthrinsing programs.

The viability of community dental programs is influenced by various factors, including costs and effectiveness. Costs, in turn, are influenced by the prices and productivity of resources, and variations in these will influence not only comparisons among programs providing a homogeneous service but also any conclusions that can be drawn about cost-effectiveness. This paper eliminates wage effects and examines resource productivity and returns to scale in relationship to the size of a group of school-based mouthrinsing programs. The research questions were to determine: 1) whether the programs exhibit increasing, decreasing, or constant returns to scale, and 2) the productivity of labor and capital. Data from 14 programs in the US were pooled for 2 yr to yield 28 observations. The production relationship between output (numbers of participants) and inputs (labor and capital) was specified in a Cobb-Douglas model. Findings were that 1) the programs exhibited decreasing returns to scale (P less than 0.01); and 2) the average and marginal productivities of labor and capital declined (P less than 0.001). The implications of these findings are that, with equal wages and homogeneous labor, the average cost of mouthrinsing per participant would have increased as a function of the size of these programs. To the extent that the economics of community dental programs are influenced not only by the costs and productivity of the resources they use but also by their size, there may be some value in research on the economics of optimum program size and the role of management in program organization.

Dental school finances: current status.

Total expenditures and revenues of 58 US dental school were derived from reports of the ADA Division of Educational Measurements. These financial data were studied by type of dental school (public, state-related private, and private) and by expenditure/revenue categories. Dental schools showed little diversity in expenditures: most were directed toward instruction; few were directed toward research or continuing education. Several distinctive patterns among the three types of dental schools in revenues were observed. Two configurations emerged: public and state-related private dental schools receive more than 75% of their revenues from government and tuition, and private dental schools, more than 50%.

Return on investment.

Return on investment is an excellent mechanism for evaluating large practice purchasing decisions. Whether you are purchasing a new practice, opening an office, building a new facility, recruiting an associate or adding technology, the issue that always should be evaluated is whether the investment will create a positive return for the practice and, if so, in what period. While most dental investments actually provide a positive return on investment within 12 months, larger investments, such as purchasing a practice or opening new offices, may require several years to gain a positive return. They still may be good decisions. At the very least, return-on-investment considerations allow dentists to evaluate options from a business-plan perspective, rather than simply making uninformed decisions.

Practice valuation: an analytical approach.

Purchasing a dental practice is difficult. To help make this decision process more manageable, practitioners, practice management consultants, and practice appraisers often use standard valuation methodologies. Although useful, many of these models are simplistic, arbitrary, and dependent on criteria that are often susceptible to substantial subjectivity. Therefore, practice valuation results are often disputed. The capitalization of income method removes much of the subjectivity often associated with practice valuation and provides a more reliable assessment of the value of a practice.

To solo or not to solo.

An analyst from the ADA Survey Center provides a brief overview of the differences and similarities of solo and nonsolo (group) practices, based on data gathered from the 1995 Survey of Dental Practice.

Trend analysis of dental practice rent and mortgage expenses: 1989-1995.

BACKGROUND: The authors analyzed trends for rent and mortgage, as reported by independent active private practitioners, for the period of 1989-1995. Rent and mortgage were analyzed overall and by different characteristics. METHODS: In the ADA's annual "Survey of Dental Practice," dentists reported gross billings and net incomes, as well as itemized practice expenses. The authors tabulated survey responses over time to develop trends and compare rent and mortgage expenses for each year. If trends over time were not exhibited, the authors combined multiple years of data to develop more reliable statistics. RESULTS: Approximately three-fourths of independent active private practitioners reported rent but no mortgage expenses. The percentages of practitioners who reported rent or mortgage was stable over time. The percentage reporting rent only as an expense increased with the number of dentists in the practice, the age of the reporting dentist and the number of office locations. In contrast, the opposite was true for dentists reporting mortgage only as an expense. CONCLUSIONS: The authors found that office rental is more common than is office ownership and that mortgages as a percentage of gross billings and in dollar amounts were similar to rents. They also found that because the cost of office space as a percentage of gross billings decreased as the number of dentists in the practice increased, limited economies of scale may be present in the cost of dental office space. PRACTICE IMPLICATIONS: There is not a large financial advantage to ownership, so renting is likely to remain an important way to acquire office space. As only limited economies of scale exist in office space expenses, many group practices may choose to rent office space.

Dental bodies corporate and their approach to customer care.

For many years the 27 bodies corporate registered with the General Dental Council were of little interest to most people in the UK dental profession, serving only as an anachronistic reminder of a bygone period. How times change. Although they still have only a small share of the dental market - with 4% of all dentists in the UK in early 1999 - they have expanded rapidly from a small base and are expected to continue to do so in the future. The reasons behind this growth are numerous and include such factors as: deregulation of the profession allowing dentists to advertise thus facilitating company branding; a general move away from NHS dentistry; a growing consumerism amongst the general public; precedents set by pharmacists and opticians; and, last but not least, the belief of venture capitalists amongst others that investment in dentistry will yield attractive returns.