1,937 research outputs found
Methylmercury varies more than one order of magnitude in commercial European rice
P.M. thanks the Royal Thai Government for funding and C.C.B. thanks the School of Natural and Computing Science and PS Analytical for funding.Peer reviewedPostprin
Three Stage Cool Flame Droplet Burning Behavior of n-Alkane Droplets at Elevated Pressure Conditions: Hot, Warm and Cool Flame
Transient, isolated n-alkane droplet combustion is simulated at elevated pressure for helium-diluent substituted-air mixtures. We report the presence of unique quasi-steady, three-stage burning behavior of large sphero-symmetric n-alkane droplets at these elevated pressures and helium substituted ambient fractions. Upon initiation of reaction, hot-flame diffusive burning of large droplets is initiated that radiatively extinguishes to establish cool flame burning conditions in nitrogen/oxygen air at atmospheric and elevated pressures. However, at elevated pressure and moderate helium substitution for nitrogen ( X He > 20%), the initiated cool flame burning proceeds through two distinct, quasi-steady-state, cool flame burning conditions. The classical Hot flame ( 1500 K) radiatively extinguishes into a Warm flame burning mode at a moderate maximum reaction zone temperature ( 970 K), followed by a transition to a lower temperature ( 765 K), quasi-steady Cool flame burning condition. The reaction zone (flame) temperatures are associated with distinctly different yields in intermediate reaction products within the reaction zones and surrounding near-field, and the flame-standoff ratios characterizing each burning mode progressively decrease. The presence of all three stages first appears with helium substitution near 20%, and the duration of each stage is observed to be strongly dependent on helium substitutions level between 2060%. For helium substitution greater than 60%, the hot flame extinction is followed by only the lower temperature cool flame burning mode. In addition to the strong coupling between the diffusive loss of both energy and species and the slowly evolving degenerate branching in the low and negative temperature coefficient (NTC) kinetic regimes, the competition between the low-temperature chain branching and intermediate-temperature chain termination reactions control the Warm and Cool flame quasi-steady conditions and transitioning dynamics
Laser-Assisted In Vitro Fertilization Facilitates Fertilization of Vitrified-Warmed C57BL/6 Mouse Oocytes with Fresh and Frozen-Thawed Spermatozoa, Producing Live Pups
The utility of cryopreserved mouse gametes for reproduction of transgenic mice depends on development of assisted reproductive technologies, including vitrification of unfertilized mouse oocytes. Due to hardening of the zona pellucida, spermatozoa are often unable to penetrate vitrified-warmed (V-W) oocytes. Laser-assisted in vitro fertilization (LAIVF) facilitates fertilization by allowing easier penetration of spermatozoa through a perforation in the zona. We investigated the efficiency of V-W C57BL/6NTac oocytes drilled by the XYClone laser, compared to fresh oocytes. By using DAP213 for cryoprotection, 83% (1,470/1,762) of vitrified oocytes were recovered after warming and 78% were viable. Four groups were evaluated for two-cell embryo and live offspring efficiency: 1) LAIVF using V-W oocytes, 2) LAIVF using fresh oocytes, 3) conventional IVF using V-W oocytes and 4) conventional IVF using fresh oocytes. First, the groups were tested using fresh C57BL/6NTac spermatozoa (74% motile, 15 million/ml). LAIVF markedly improved the two-cell embryo efficiency using both V-W (76%, 229/298) and fresh oocytes (69%, 135/197), compared to conventional IVF (7%, 12/182; 6%, 14/235, respectively). Then, frozen-thawed C57BL/6NTac spermatozoa (35% motile, 15 million/ml) were used and LAIVF was again found to enhance fertilization efficiency, with two-cell embryo rates of 87% (298/343) using V-W oocytes (P<0.05, compared to fresh spermatozoa), and 73% (195/266) using fresh oocytes. Conventional IVF with frozen-thawed spermatozoa using V-W (6%, 10/168) and fresh (5%, 15/323) oocytes produced few two-cell embryos. Although live offspring efficiency following embryo transfer was greater with conventional IVF (35%, 18/51; LAIVF: 6%, 50/784), advantage was seen with LAIVF in live offspring obtained from total oocytes (5%, 50/1,010; conventional IVF: 2%, 18/908). Our results demonstrated that zona-drilled V-W mouse oocytes can be used for IVF procedures using both fresh and frozen-thawed spermatozoa, producing live pups. The ability to cryopreserve mouse gametes for LAIVF may facilitate management of large-scale transgenic mouse production facilities.National Institutes of Health (U.S.) (NIH National Research Service Award (T32-RR070036))National Institutes of Health (U.S.) (NIH National Cancer Institute Program Project (P01CA10451)
TECHNO-ECONOMIC ANALYSIS OF USING PV CURTAIN WALLS IN HOT ARID ENVIRONMENTCASE STUDY; MIXED-USE BUILDING, JEDDAH, KSA
Nowadays the world no longer has a choice to reduce the dependency of non-renewable energy resources, especially in buildings. This type of energy like fossil fuel is responsible for global warming and the climate change phenomenon. The construction industry has to depend on renewable energy to improve environmental impacts while operating the buildings. The most promising technologies for buildings are photovoltaic panels system which converts solar radiation into electricity without harming the environment. PV system is not only used as top-roof panels but also it can play an important role in the exterior building cladding and in curtain wall system as well. Building-integrated PV (BIPV) system has two functions the first is used as a façade cladding and the second is power generation for building operation. This research studies the PV curtain wall as a BIPV system and explains why this system is better than the traditional curtain wall through its environmental performance and initial, and operation costs. Based on the analysed tabulated feasibility study considering energy savings outcome and system cost, PV curtain walls proved technical, environmental and economic viability. The paper’s case study in Jeddah-KSA provides a real example of how PV curtain wall application plays a fundamental role in achieving high energy performance standards as well as maximize the financial return of investment
Revisiting Politicide: State Annihilation in Israel/Palestine
State annihilation is a persistent concern in Israel/Palestine. While the specter of Israel’s destruction increasingly haunts Israeli public political debates, the actual materialization of Palestinian statehood seems to be permanently suspended, caught in an ever-protracted process of state-building. The current paper claims that to understand the unfolding of the discursive formations, as well as the spatial dimensions of conflict and control in Israel/Palestine, we should explicate the workings of the processes of politicide. Politicide, in this regard, denotes the eradication of the political existence of a group and sabotaging the turning of a community of people into a polity. This analysis suggests that the insistence that the State of Israel is under threat of extinction should be understood as a speech act, a performative reiteration, which allows for the securitization of Israeli rule in the occupied Palestinian territory, a securitization which then serves to rationalize the ongoing concrete politicide of the Palestinians. Elaborating on the concept of politicide, and diverging from defining it solely through the use of brute violence, this examination suggests that what is often overlooked in discussions of politicide are the seemingly more benign means of its implementation, the micro-power mechanisms of spatial control, prohibitions and regulations
Ribbon Crystals
A repetitive crystal-like pattern is spontaneously formed upon the twisting of straight ribbons. The pattern is akin to a tessellation with isosceles triangles, and it can easily be demonstrated with ribbons cut from an overhead transparency. We give a general description of developable ribbons using a ruled procedure where ribbons are uniquely described by two generating functions. This construction defines a differentiable frame, the ribbon frame, which does not have singular points, whereby we avoid the shortcomings of the Frenet-Serret frame. The observed spontaneous pattern is modeled using planar triangles and cylindrical arcs, and the ribbon structure is shown to arise from a maximization of the end-to-end length of the ribbon, i.e. from an optimal use of ribbon length. The phenomenon is discussed in the perspectives of incompatible intrinsic geometries and of the emergence of long-range order
Impact of the COVID-19 Pandemic on Medical Product Procurement, Prices, and Supply Chain in Zimbabwe: Lessons for Supply Chain Resiliency
BACKGROUND: The COVID-19 pandemic has disrupted global health supply chains including manufacturing, storage, and delivery of essential medicines, testing kits, personal protective equipment, and laboratory reagents. We sought to document how pandemic impacted the procurement, prices, and supply chain of medical products in Zimbabwe.
METHODS: We conducted semistructured in-depth key informant interviews with 36 health system stakeholders in Zimbabwe involved in medicine procurement. Respondents included pharmacists, regulatory officers, and procurement and supply chain management professionals from public and private sectors.
RESULTS: Before the COVID-19 pandemic, respondents described experiencing long-standing resource constraints, medicine shortages, foreign currency shortages, and supply chain inefficiencies. The pandemic exacerbated this situation due to supply constraints, export restrictions, medicine shortages, and movement restrictions that disrupted logistical and stock management systems. Competitive bidding and tendering processes experienced reduced participation by international suppliers. Significant price increases were initially observed among internationally shipped medicines and for personal protective equipment to cover additional freight costs. COVID-19 pandemic impacts were moderated by reduced patient demand and lower health services utilization, resulting in fewer supply shocks and less price volatility. Further, health system adaptations such as switching treatment regimens, modifying dispensing schedules based on stock availability, redistributing stock of medicines among facilities, and new service delivery models such as integrated outreach services helped ensure continued patient access to medicines.
CONCLUSIONS: Our findings highlight the need for policies that ensure continuity in access to health services and medical products, even during a pandemic, by avoiding blanket restrictions on medical product exports and imports. Pooled procurement, especially at regional and global levels, with long-term service agreements may help achieve greater resiliency to supply and price shocks from supply chain disruptions. Interventions across manufacturing, trade, and regulatory policy and service delivery models are also needed for supply chain resiliency
Common mental disorders in mothers of children attending out-patient malnutrition clinics in rural North-western Nigeria: a cross-sectional study.
BACKGROUND: Children with uncomplicated severe acute malnutrition are managed routinely within out-patient malnutrition treatment programs. These programs do not offer maternal mental health support services, despite maternal mental health playing a significant role in the nutritional status of children. Additionally, the burden of maternal Common Mental Disorders (CMDs) is poorly described among mothers of children attending these programs. This study thus determined the burden and risk factors for maternal CMDs among children attending out-patient malnutrition clinics in rural North-western Nigeria. METHODS: We conducted a cross-sectional study among 204 mothers of children with severe acute malnutrition who attending eight out-patient malnutrition clinics in Jigawa, North-western Nigeria. We used the World Health Organization Self-Reporting Questionnaire-20 (WHO SRQ-20) screening tool, a recognised and validated proxy measure for CMDs to identify mothers with CMDs. The prevalence of maternal CMDs was determined by identifying the proportion of mothers with SRQ scores of ≥8. Risk factors for CMD were determined using multivariable logistic regression. RESULTS: Maternal CMD prevalence in children attending these facilities was high at 40.7%. Non-receipt of oral polio vaccine (OPV) (AOR 6.23, 95%CI 1.85 to 20.92) increased the odds for CMD. While spousal age above 40 (AOR 0.95, 95%CI 0.90 to 0.99) and long years spent married (AOR 0.92, 95%CI 0.85 to 0.98) decreased the odds for CMD. CONCLUSIONS: Our findings indicate maternal CMD burden is high in out-patient malnutrition clinics in North-western Nigeria. Maternal mental health services would need to be integrated into the community management of acute malnutrition programs to provide more holistic care, and possibly improve long-term outcomes after discharge from these programs
- …
