On-off cyclic testing of a micro-cogeneration Stirling unit

Stirling engines are a promising candidate for micro-cogeneration in residential and small-scale tertiary applications. Due to the variability of energy demand profiles and electricity tariffs, real applications often require to operate the cogeneration unit with multiple daily starts and stops, especially during summer and intermediate seasons. This work focuses on the experimental analysis of a commercial 1 kWel Stirling unit, burning natural gas and generating 8 kWth of useful heat through hot water and up to 12 kWth with an auxiliary burner, when subjected to cyclic on-off operation. The scope is collecting useful data about energy balances and emissions during on-off transients, which can be later used to optimize the management of the cogeneration unit when coupled with real users. Different cyclic tests are experimented (with intermediate stops and operation of either one or two burners), keeping the temperature of the cogeneration water at the unit inlet at 50°C and its mass flow rate at the nominal value of 0.194 kg/s. The Stirling unit has shown an electrical efficiency of 8.9%, based on Lower Heating Value (LHV), in the most favorable cyclic test and 8.2% in the worst case, while thermal efficiency ranges between 91.0 and 92.6%. For comparison, the steady state electrical efficiency is 10.8% (LHV) while the thermal is 90.1% with only one burner running in full cogeneration mode. Steady state efficiencies become 7.2% and 92.0% (LHV), respectively, with the auxiliary burner running. The significant reduction of average electrical efficiency suggests the necessity to limit the frequency of starts and stops in real operation. Emissions show modest peaks in NOx and CO, which do not compromise the environmental impact, confirming the low emission combustion features of the Stirling unit

Comparison of three different types of implantâ supported fixed dental prostheses: A longâ term retrospective study of clinical outcomes and costâ effectiveness

ObjectiveTo study the performance of 2â 3 posterior boneâ level dental implants constructed with either three nonâ splinted crowns (NSC), three splinted crowns (SC), or a 3â unit implantâ supported bridge over two implants (ISB).Material and methodsPatients treated with three metalâ ceramic NSC, SC, or an ISB were included in the present retrospective study. Implant survival and success rate as well as all biological and technical complications were collected. The cost associated with each of the treatment options was evaluated in the comparative analysis.ResultsOne hundred and fortyâ five patients (40 NSC, 52 SC, and 53 in the ISB) receiving 382 boneâ level implants (120 NSC, 106 ISB, and 156 SC) were included (mean followâ up of 76.2 months). Lack of success was observed in 33.8% of the total patient sample, being lower in the ISB group. Implant survival rates were 92.5% in the NSC, 100% in the ISB, and 88.5% in the SC, with significant difference noted between the ISB and SC (p = 0.01). Overall, 9.9% of the total implants were found to have periâ implantitis (PI), with 16.7% in the SC, 7.5% in the NSC, and 2.8% in the ISB. Patients presenting prosthodontic complications were significantly higher in NSC (32.5%) than ISB (13.2%) and SC (15.4%). The total cost of the ISB group was significantly lower when compared to the NSC and SC groups (p < 0.001).ConclusionsAn 3â unit implantâ supported bridge restoring 2 implants seems to present the most ideal longâ term therapeutic solution, among the investigated approaches in this study, in rehabilitating a 3â unit edentulous area.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149366/1/clr13415.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149366/2/clr13415_am.pd

Outcomes of root resection therapy up to 16.8Â years: A retrospective study in an academic setting

BackgroundRoot resection has been considered a viable treatment option for molars with furcation defects. However, need of a multidisciplinary approach could potentially deem this procedure less successful. The aim of the present article was to determine survival rates of root resection procedure and reasons for failure in an academic setting.MethodsPatient- related demographic data, medical history information, and relevant data pertaining to the root- resected teeth performed from January 1990 to September 2017 were reviewed through electronic and paper chart. Survival rates were analyzed using Kaplan- Meier estimate. Association between the reasons for failure and independent variables was established by a Pearson Chi- squared and Kruskal- Wallis test.ResultsA total of 85 patients with an average follow- up of 5 ± 4.3 years (range: 1 to 16.8 years) were included in the present article. A total of 47 molar teeth treated with root resection remained as part of the dentition (55.3%) and 38 (44.7%) failed. The mean survival time with the Kaplan- Mayer analysis was 109.9 months (9.1 years). Fracture (39.5%), caries (26.3%), and periodontal disease (23.7%) were the most common causes for failure. Interestingly, the majority of failures occurred in the first 4 years after therapy (n = 31; 81.5% of all failures).ConclusionsRoot resection therapy remains a treatment solution for molars with furcation defects. In an academic setting, >50% of teeth remained functional after 9 years of root resection therapy.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154884/1/jper10422.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154884/2/jper10422_am.pd

Experimental and numerical study of a micro-cogeneration Stirling unit under diverse conditions of the working fluid

Micro-cogeneration Stirling units are promising for residential applications because of high total efficiencies, favorable ratios of thermal to electrical powers and low CO as well as NOx emissions. This work focuses on the experimental and the numerical analysis of a commercial unit generating 8 kW of hot water (up to 15 kW with an auxiliary burner) and 1 kW of electricity burning natural gas. In the experimental campaign, the initial pressure of the working fluid is changed in a range from 9 to 24 barg – 20 barg being the nominal value – while the inlet temperature of the water loop and its mass flow rate are kept at the nominal conditions of, respectively, 50°C and 0.194 kg/s. The experimental results indicate clearly that the initial pressure of the working fluid – Nitrogen – affects strongly the net electrical power output and efficiency. The best performance for the output and efficiency of 943 W and 9.6% (based on the higher heating value of the burnt natural gas) are achieved at 22 barg. On the other hand, the thermal power trend indicates a maximum value of 8420 W at the working pressure of 24 barg, which corresponds to a thermal efficiency of 84.7% (again based on higher heating value). Measurements are coupled to a detailed model based on a modification of the work by Urieli and Berchowitz. Thanks to the tuning with the experimental results, the numerical model allows investigating the profiles of the main thermodynamic parameters and heat losses during the cycle, as well as estimating those physical properties that are not directly measurable. The major losses turn to be the wall parasitic heat conduction from heater to cooler and the non-unitary effectiveness of the regenerator

Using periodontal staging and grading system as a prognostic factor for future tooth loss: A long- term retrospective study

BackgroundA new classification of periodontal diseases aimed to identify periodontal disease based on a multidimensional staging and grading system has been recently proposed. However, up to date, its prognostic predictive capability has not been investigated. The aim of this study was to assess if parameters included in the new classification were predictive of tooth loss after a long- term follow- up (>10 years) in patients with periodontitis.MethodsPatients presented with periodontitis at the University of Michigan between January 1966 and January 2004 were screened and categorized according to the new classification of periodontitis. Number/Reasons of teeth loss in patients who underwent at least one session/year of maintenance during the entire follow- up period were extracted and used to analyze the prognostic capabilities of variables (staging, grading, and Extent) included in the new classification.ResultsA total number of 292 patients with a mean follow- up of 289.7 ± 79.6 months were included. 31 (10.6%) patients were classified as Stage 1, 85 (29.1%) as Stage 2, 146 (50%) as Stage 3, and 30 (10.3%) as Stage 4. For grading, 34 (11.7%) were classified as Grade A, 193 (66.1%) as Grade B, and 65 (22.2%) as Grade C. Results of multilevel Cox regression analyses revealed a statistically significant association between stage (HR:3.73 between Stage 4 and Stage 1) and grade (HR: 4.83 between Grade C and Grade A) at baseline and periodontal related tooth loss, whereas no differences were detected for the extent of periodontitis.ConclusionThis study provides the initial evidence regarding the predictive ability of the new classification of periodontitis. Patients in either Stage 4 or Grade C showed a significantly higher periodontal- related tooth loss.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154975/1/jper10442_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154975/2/jper10442.pd

Modeling and Testing of a Micro-cogeneration Stirling Engine Under Diverse Conditions of the Working Fluid

Abstract Micro-cogeneration Stirling engines are promising for residential applications. This work focuses on the experimental and numerical analyses of a commercial unit generating 8 kW of hot water and 1 kW of electricity burning natural gas. Measurements are coupled to a detailed model based on a modification of Urieli and Berchowitz's work. The results indicate that the thermal efficiency is influenced by the water loop inlet temperature, varying from 90% at 30 °C to 84% at 70 °C (HHV-based). The measured and simulated powers of the engine are in the 900-964 W range depending on the water temperature and differ by less than 4%. Net electric efficiency of the engine is 15% and of the whole cogeneration unit above 9% (HHV-based). Helium instead of Nitrogen as working fluid is expected to increase the performance

Influence of keratinized mucosa on the surgical therapeutical outcomes of peri-implantitis

AimTo assess the impact of keratinized mucosa (KM) width around dental implants on surgical therapeutic outcomes when treating peri- implantitis.Material and MethodsSurgically treated peri- implantitis implants were divided into two groups (KM width  .01). Between T1 and T2, no major differences were noted on PPD reduction, BOP and MBL changes between the two groups. GEE modelling demonstrated that MBL severity prior to surgical therapy was a better predictor for implant survival than KM width.ConclusionSurgical outcome in treating peri- implantitis was influenced by the severity of bone loss present at the time of treatment and not by the presence of KM at the time of treatment.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154633/1/jcpe13250.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154633/2/jcpe13250_am.pd

The effect of quarantine due to Covid-19 pandemic on seizure frequency in 102 adult people with epilepsy from Apulia and Basilicata regions, Southern Italy

Objective: following the COVID-19 pandemic, a quarantine was imposed to all of regions Italy by 9th March until 3rd May 2020. We investigated the effect of COVID-19 infection and quarantine on seizure frequency in adult people with epilepsy (PwE) of Apulia and Basilicata regions, Southern Italy. Methods: This is an observational, retrospective study based on prospective data collection of 102 successive PWE. The frequency of seizures was evaluated during pre-quarantine (January- February), quarantine (March-April), and post-quarantine period (May-June), while PwE were divided into A) cases responding to treatment with ≤ 1 seizure per year; B) cases responding to treatment with 2-5 seizure per year; C) cases with drug-resistant epilepsy with ≤ 4 seizures per month; D) cases with drug-resistant epilepsy with 5-10 seizures per month. PwE underwent several self-report questionnaires regarding therapeutic compliance, mood, stress and sleep during quarantine period. Results: Approximately 50 % of PwE showed seizure frequency changes (22.55 % an increase and 27.45 % a reduction) during quarantine. Seizure frequency significantly (p &lt; 0.05) increased in PwE responding to treatment with ≤ 1 seizure per year, while significantly (p &lt; 0.05) reduced in PwE with drug-resistant epilepsy with 5-10 seizures per month. The data was not influenced by therapeutic adherence, sleep and depression. The analysis of anxiety showed a moderate level of anxiety in PwE responding to treatment with &lt; 1 seizure per year, while moderate stress was perceived by all PwE. Seizure frequency changes were related to quarantine, but not to COVID-19 infection. In fact, unlike other regions of Italy, particularly Northern Italy, Apulia and Basilicata regions were less affected by COVID-19 infection, and almost all PwE recognized the quarantine as a stressful event. Emotional distress and anxiety due to social isolation, but also the relative reduction of triggers for epileptic seizures were the most important factors for changes in seizure frequency. Conclusions: Our study adds to the growing concern that the indirect effects of COVID-19 pandemic will far outstrip the direct consequences of the infection

Tegument Glycoproteins and Cathepsins of Newly Excysted Juvenile Fasciola hepatica Carry Mannosidic and Paucimannosidic N-glycans

Recently, the prevalence of Fasciola hepatica in some areas has increased considerably and the availability of a vaccine to protect livestock from infection would represent a major advance in tools available for controlling this disease. To date, most vaccine-target discovery research on this parasite has concentrated on proteomic and transcriptomic approaches whereas little work has been carried out on glycosylation. As the F. hepatica tegument (Teg) may contain glycans potentially relevant to vaccine development and the Newly Excysted Juvenile (NEJ) is the first lifecycle stage in contact with the definitive host, our work has focused on assessing the glycosylation of the NEJTeg and identifying the NEJTeg glycoprotein repertoire. After in vitro excystation, NEJ were fixed and NEJTeg was extracted. Matrix-assisted laser desorption ionisation-time of flight-mass spectrometry (MALDI-TOF-MS) analysis of released N-glycans revealed that oligomannose and core-fucosylated truncated N-glycans were the most dominant glycan types. By lectin binding studies these glycans were identified mainly on the NEJ surface, together with the oral and ventral suckers. NEJTeg glycoproteins were affinity purified after targeted biotinylation of the glycans and identified using liquid chromatography and tandem mass spectrometry (LC-MS/MS). From the total set of proteins previously identified in NEJTeg, eighteen were also detected in the glycosylated fraction, including the F. hepatica Cathepsin B3 (FhCB3) and two of the Cathepsin L3 (FhCL3) proteins, among others. To confirm glycosylation of cathepsins, analysis at the glycopeptide level by LC-ESI-ion-trap-MS/MS with collision-induced dissociation (CID) and electron-transfer dissociation (ETD) was carried out. We established that cathepsin B1 (FhCB1) on position N80, and FhCL3 (BN1106_s10139B000014, scaffold10139) on position N153, carry unusual paucimannosidic Man2GlcNAc2 glycans. To our knowledge, this is the first description of F. hepatica NEJ glycosylation and the first report of N-glycosylation of F. hepatica cathepsins. The significance of these findings for immunological studies and vaccine development is discussed

Development of a nomogram for the prediction of periodontal tooth loss using the staging and grading system: A long- term cohort study

AimTo develop and internally validate a nomogram built on a multivariate prediction model including parameters from the new classification of periodontal diseases, able to predict, at baseline, the occurrence of tooth loss due to periodontal reason (TLP).Materials and MethodsA total of 315 individuals diagnosed with periodontal disease and receiving a minimum of one annual supportive periodontal therapy visit were included in the study. Patients were staged and graded based upon baseline data. The population was divided into a development (254 patients) and a validation (61 patients) cohort to allow subsequent temporal validation of the model. According to the TLP at the 10- year follow- up, patients were categorized as - low tooth loss- (- ¤ 1 TLP) or - high tooth loss- (- ¥ 2 TLP). Bootstrap internal validation was performed on the whole data set to calculate an optimism- corrected estimate of performance.ResultsThe generated nomogram showed a strong predictive capability (AUC = 0.81) and good calibration with an intercept = 0 and slope = 1. These findings were confirmed by internal validation using bootstrapping (average bootstrap AUC = 0.83).ConclusionsThe clinical implementation of the present nomogram guides the prediction of patients with high risk of disease progression and subsequent tooth loss for personalized care.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163380/2/jcpe13362.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163380/1/jcpe13362_am.pd