49 research outputs found

    Sustainable Hydrogen Production via Sorption Enhanced Reforming of Complex Biorefinery Side Streams in a Fixed Bed Adiabatic Reactor

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    In this work, sorption enhanced steam reforming is explored as a potential solution for the valorization of gaseous streams recovered from biorefinery hydrogenation processes. The hydrogen content of such streams limits the hydrocarbon conversion in conventional steam reforming due to thermodynamic and kinetic constraints. A previously developed 1D dynamic heterogeneous model of an adiabatic reactor was thus applied to evaluate the effect of H-2 dilution on the performance indicators of the sorption enhanced reforming process. The mathematical model analysis highlights that despite of CO2 capture by the sorbent favorably modifies the thermodynamics of syngas production, H-2 dilution worsens the performance of the sorption enhanced reforming of model H-2/CH4 streams with respect to pure CH4. Results show a drop of 17% for CH4 conversion and a reduction of 15.4% of the captured CO2 on passing from pure methane to a H-2/CH4 feed with a 40/60 molar ratio. However, on increasing the heat capacity of the bed, by replacing part of the sorbent with an inert heat carrier, better performances are calculated for the H-2/CH4 feed matching the pure CH4 case. The presence of C2+ hydrocarbons is assessed as well and the results show a significant improvement in the reformer's performance; in the case of a stream composed of H-2/CH4/C3H8 with a molar ratio 40/45/15, the total hydrocarbon conversion grows to 92.8%, CO2 capture ratio to 82.6%, and H-2 purity to 95.6%. The positive effect is associated with thermal factors that promote the reaction kinetics. Thus, the suitability of the sorption enhanced reforming technology to H-2-rich and C-poor streams is strictly composition dependent; by cofeeding of C2+ hydrocarbons, the process turns into a remarkable solution for converting gaseous streams in pure H-2

    Temporomandibular disorders and fibromyalgia: A narrative review

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    Temporomandibular disorder (TMD) and fibromyalgia (FM) have some clinical characteristics in common, for instance the chronic evolution, the pathophysiology incompletely understood and a multifactorial genesis. The incidence and the relationship between TMD and FM patients are the aims of this review. A MEDLINE and PubMed search were performed for the key words “temporomandibular disorder” AND “fibromyalgia” from 2000 to present. A total of 19 papers were included in our review, accounting for 5449 patients. Ten studies, reporting a total of 4945 patients with TMD, showed that only 16.5% of these patients had diagnosis of FM, whereas 12 studies, reporting a total of 504 patients with FM, demonstrated that 77.0% of these patients had diagnosis of TMD. A comorbid relationship exists between TMD and FM. The complexity of both diseases shows the importance of a multimodal and interdisciplinary

    Scientific trends in clinical research on zirconia dental implants: A bibliometric review

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    Background: The clinical use of zirconia implants has been shown to increase steadily due to their biological, aesthetic, and physical properties; therefore, this bibliometric study aimed to review the clinical research and co-authors in the field of zirconia dental implant rehabilitation. Methods: We searched Scopus and Web of Science databases using a comprehensive search strategy to 5 October 2020, and independently paired reviewers who screened studies, and collected data with inclusion criteria restricted to clinical research only (either prospective or retrospective). Data on article title, co-authors, number of citations received, journal details, publication year, country and institution involved, funding, study design, marginal bone loss, survival rate, failure, follow-up, and the author’s bibliometric data were collected and evaluated. Results: A total of 29 clinical studies were published between 2008 and 2020 as 41.4% were prospective cohort studies and 48.3% originated from Germany. Most of the included studies had been published in Clinical Oral Implant Research (n = 12), and the most productive institution was the Medical Center of University of Freiburg. The author with the largest number of clinical studies on zirconia implants was Kohal R.J. (n = 10), followed by Spies B.C. (n = 8). Conclusions: This study revealed that zirconia implants have been more prominent in the last ten years, which is a valuable option for oral rehabilitation with marginal bone loss and survival rate comparable to titanium dental implants

    The effect of menopause hypoestrogenism on osteogenic differentiation of periodontal ligament cells (PDLC) and stem cells (PDLCs): A systematic review

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    (1) Background: Menopause is a physiological condition typified by drastic hormonal changes, and the effects of this transition have long-term significant clinical implications on the general health, including symptoms or physical changes. In menopausal women, the periodontium can be affected directly or through neural mechanism by oestrogen (E2) deficiency. The majority of the biological effects of E2 are modulated via both oestrogen receptor-α (ERα) and oestrogen receptor-β (ERβ). There is evidence that hypoestrogenism has a substantial impact on the aetiology, manifestation and severity of periodontitis, via the regulation of the expression of osteoproges-terin and RANKL in human periodontal ligament cells through ERβ. However, the mechanistic understanding of oestrogen in periodontal status has been partially clarified. The aim of this paper was to synopsize the recent scientific evidence concerning the link between the menopause and periodontitis, through the investigation of physio-pathological impact of the oestrogen deficiency on osteogenic differentiation of PDLSCs and PDLSC, as well as the dynamic change of ERα and ERβ. (2) Methods: Search was conducted for significant studies by exploring electronic PubMed and EMBASE databases, and it was independently performed by two researchers. All studies on the impact of oestrogen level on alveolar bone resorption were searched from 2005 to July 2020. Data selection was in concordance with PRISMA guidelines. (3) Results: Eight studies met the criteria and were included in this systematic review. All studies reported that oestrogen deficiency impairs the osteogenic and osteoblastic differentiation of PDL cells and oestrogen affects the bone formation capacity of cells. Seven studies were conducted on animal samples, divided into two groups: the OVX animals and animals who received the sham operation. (4) Conclusions: There is a multitude of data available showing the influence of menopause on periodontal status. However, the evidence of this line to investigation needs more research and could help explain the physiological linkage between menopause state and periodontal disease

    Exploring the role of Fusobacterium nucleatum in preterm birth: A narrative review

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    In recent years, substantive attention has been drawn to the relationship between oral microbiome homeostatic equilibrium disruption and systemic health, demonstrating the negative impacts of this reciprocal biological interplay. Increasingly, there is a concern over the potential noxious effect of oral microbiome dysbiosis on obstetric poor outcomes, focusing on preterm birth. This epidemiological observation remains unexplained, although biologically plausible mechanism has been proposed. Intrauterine infection has long been associated with adverse pregnancy, when the elicitation of an immune response is determinant. There is evidence that Fusobacterium nucleatum (FN), a Gram-negative anaerobe ubiquitous in the oral cavity, infects the mouse placenta originating in the decidua basalis. Based on the current data in literature, we performed a review to provide resources for the explanation of the potential impact of microbiome dysbiosis on poor obstetric outcomes, focusing on the role of FN

    Trade in Prevost’s squirrels: legality, risk for introduction and disease transmission

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    quirrels traded for pets or consumption have the potential to be vectors for zoonotic disease transmission and to establish themselves as invasive species. Callosciurus spp. (Greek for beautiful squirrel) are popular in the pet trade due to their medium size and many colour variants, though several feral populations have established themselves in various parts of the world and these wild-caught individuals can carry and spread infectious diseases. Here, we investigate the live trade in Prevost’s squirrels (C. prevosti) in Indonesia where they are naturally found on the islands of Sumatra, Bangka and Borneo. Between 2016 and 2024, we recorded 284 Prevost’s squirrels for sale, viz., 115 in the physical markets and 169 online. We detected the species for sale in Sumatra (13 individuals), Bangka (7) and Borneo (3), i.e. within their natural range, but also on Java (242) and Bali (4). The mean asking price per individual was US$63, and younger individuals commanded higher prices than older ones. Asking prices were not higher in cities further away from the species’ native range nor in cities with higher purchasing power. All individuals were wild-caught, and with a domestic quota of five individuals allowed to be traded as pets per year (45 over the study period) most of this trade is illegal under Indonesian law. This is distinctly different from trade in Prevost’s squirrels in for instance Europe or the USA where legally captive-bred individuals are offered for sale. In Indonesia the illegal trade happens in the open and despite the risk of the spread of zoonotic diseases wherever it is traded there appears to be little incentive on the side of the authorities to curb this trade. Their widespread availability on Java and Bali risks the accidental or deliberate introduction on these two islands. Better coordination is needed between the Indonesian authorities, online sales sites, pet traders and consumers to stop the sale of illegally obtained Prevost’s squirrels to limit the risk of them becoming invasive species or contributing to the spread of emerging infectious diseases
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