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A facile method for making porous SiC ceramics from sawdust avoiding high-temperature liquid or vapor phase silicon infiltration has been outlined. Cylindrical bodies prepared by hand pressing of aqueous pastes produced from sawdust, silicon powder, sucrose, and sintering additives are subjected to freeze-drying followed by carbonization and ceramization heat-treatments to produce porous SiC. The carbon-silicon reaction is completed at a minimum temperature of 1550 °C as verified from TGA and XRD analysis. The SiC produced from sawdust particles is firmly held together by the sucrose-derived SiC. The pore channels inherited in the sawdust particle remain in the SiC ceramics. A large population of nanowires is observed throughout the sucrose-derived SiC as well as on the pore channel surfaces of SiC formed from sawdust particles. The porosity decreases from ~88 to 75 vol%, the compressive strength rises from 0.5 to 12.5 MPa, and thermal conductivity rises from 0.23 to 0.98 W/mK when the sucrose to sawdust weight ratio rises from 0.5 to 2.5. The reflection contribution (1.9–3 dB) to the total EMI shielding effectiveness (16 To 31 dB) of the porous SiC ceramics is very low compared to the absorption contribution (15–28 dB). The carbonized bodies are amenable to machinating enabling the production of near-net-shape before ceramization. The presence of large excess of silicon observed in biomorphic SiC made by molten liquid infiltration is avoided in this method.

Background The secretome of the dental pulp mesenchymal stem cells (DPMSCS-S) have an array of regenerative potential and could aid in the rehabilitation of cancer patients post-therapeutic interventions, although caution is required as DPMSC-S have shown to augment prostate cancer cells. Thus, it is vital to assess if these pro-carcinogenic effects extend to other cancer types. Objective To assess if DPMSC-S has any pro-carcinogenic effect on oral cancer, breast cancer, and melanoma cell lines. Materials and methods Conditioned media obtained from the isolated and characterized DPMSC (DPMSC-CM) were profiled using bead-based multiplex assay. AW13515 (oral cancer), MDA-MB-231 (breast cancer), and A-375 (melanoma) cell lines were exposed to 20%, 50%, and 100% DPMSC-CM for 24, 48, and 72 h. DPMSC-CM effect on the cancer cell properties and secretome were assessed. Results DPMSC-CM augmented invasion, adhesion, multi-drug resistance, DNA repair, and mitochondrial repair in AW13516 through upregulation of growth factors Ang-2, EGF, M−CSF, PDGF-AA, PDGF-BB, pro-inflammatory cytokines TNF-α, IL-2, downregulation of anti-inflammatory cytokine TGF-β1, and pro-inflammatory cytokine IL-4. In MDA-MB-231, invasion, and multi-drug resistance were augmented through upregulation of growth factors EGF, EPO, G-CSF, HGF, M−CSF, PDGF-AA, and pro-inflammatory cytokine TNF-α, CXCL10, IL-12p70. EMT, invasion, migration, and adhesion were augmented in A-375 through upregulation of growth factors Ang-2, EGF, PDGF-BB, TGF-α, pro-inflammatory cytokines TNF-α, and IL-17A. Conclusion DPMSC-CM can augment the carcinogenic properties of oral cancer, breast cancer, and melanoma cells, further animal model studies are required to validate our in-vitro findings.

Reacting flow fields are often subject to unsteadiness due to flow, reaction, diffusion, and acoustics. Further, flames can also exhibit inherent unsteadiness caused by various intrinsic instabilities. Interaction between various unsteady processes across multiple scales often makes combustion dynamics complex. Characterizing such complex dynamics is essential to ensure the safe and reliable operation of high efficiency combustion systems. Tools from nonlinear dynamics and complex systems theory provide new perspectives to analyze and interpret the data from real systems. They could also provide new ways of monitoring and controlling combustion systems. We discuss recent advances in studying unsteady combustion dynamics using the tools from dynamical systems theory and complex systems theory. We cover a range of problems involving unsteady combustion such as thermoacoustic instability, flame blowout, fire propagation, reaction chemistry and flow flame interaction.

We, herein, report an experimental study to investigate the role of local flamefront dynamics on the propagation and acceleration of cellularly unstable premixed expanding laminar flames. Using simultaneous Mie-scattering imaging and Particle Image Velocimetry, we measured the flame edge location and its adjacent flow field, which were subsequently processed to quantify the evolution of the probability density functions (pdfs) of flow velocities, curvature, normal strain rate and tangential strain rate. We showed that appropriate normalizaton of the measured quantities can unify the data from different pressures when identified with the corresponding Peclet number, defined as the ratio of the flame radius to the flame thickness. Since the flamefront is stable and smooth at lower Peclet numbers, the flame-induced flow field and stretch rates are almost uniform over the flamefront, resulting in narrow pdfs. At higher Peclet numbers, however, the flame becomes progressively more wrinkled and hence the variations in the local quantities increase leading to wider pdfs. Furthermore, while the mean curvature was found to be inversely proportional to the mean flame radius and insensitive to the cellular structure, the mean normal strain rate was strongly influenced by the cellular structure.

Hiatal hernia is frequently encountered intraoperatively during bariatric surgery. There is scarce research pertaining to the diagnostic accuracy of a preoperative diagnostic modality in comparison to intraoperative diagnosis, along with patient characteristics and related factors contributing to hiatal hernia.To identify the prevalence and associations of hiatal hernia in the bariatric patient population, we compared the diagnostic accuracy of upper gastrointestinal series and esophagogastroduodenoscopy with the intraoperative findings across various patient characteristics.Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program, Teaching Hospital, New York, USA.Retrospective study of patients from 2015 to 2018 who met National Institutes of Health criteria for bariatric surgery.There were 1094 patients included (135 males, 959 females), with an age range of 18 to 74 years. The diagnostic accuracy was determined by a sensitivity of 64.71% (95% confidence interval [CI] .55-.70), specificity of 74.38% (95% CI .71-.70), positive predictive value of 29.86% (95% CI .24-.30), negative predictive value of 92.59% (95%CI .89-90), likelihood ratio of 2.526, and P value.0001 for esophagogastroduodenoscopy; a sensitivity of 14.02% (95% CI .08-0), specificity of 98.23% (95% CI .96-.90), positive predictive value of 71.43% (95% CI .50-.80), negative predictive value of 78.35% (95% CI .74-.80), likelihood ratio 7.921, and P value.0001 were used for upper gastrointestinal series. Hiatal hernia with age60 years was 17.09% versus 48.44% at60 years (P .0001). Hiatal hernia incidence was 17% in Hispanics, 22.5% in Caucasians, and 23.10% in blacks.The prevalence of hiatal hernia is 18.92%. There is strong association between hiatal hernia and age and ethnicity and no association based on sex and body mass index. The diagnostic accuracy of upper gastrointestinal series is very low compared with that of esophagogastroduodenoscopy for hiatal hernia. Preoperative diagnosis of hiatal hernia in the bariatric population is not required based on our study. Not only does it lessen the economic burden, patient wait time, and discomfort of an additional study, but preoperative diagnosis does not change, alter, or aid in the intraoperative management of hiatal hernia considering the suboptimal accuracy of preoperative diagnostics, thus deeming them unwarranted.

A series of double selenates, as (CH3)4NLn(SeO4)2 4H2O (Ln = Rare earth ion like La, Pr, Nd, Sm, Gd, Tb, Dy) was crystallized from mixed solution and characterized in detail for their structure, vibrational and optical properties as well as thermal stabilities. The crystal structure of the praseodymium compound was obtained by single crystal X-ray diffraction (XRD) and revealed a monoclinic (C2/c) lattice with chains formed by PrO8 and SeO4 units. The chains with compositions [Pr(SeO4)4(H2O)4]─ are stacked in three dimensions and the (CH3)4N+ ions located in between them provide charge neutrality to the structure. The characterization of other compounds were carried out from powder XRD data and revealed that they all are isostructural to Pr-compound. All the functional groups were identified by Raman and IR spectroscopic studies. Solid state 77Se NMR revealed noticeable changes in selenium environment in these compounds. The optical absorption studies on the compounds show strong band edge absorptions in UV region. Thermal stabilities of the compounds, as investigated by simultaneous TG-DTA techniques indicate their sequential decompositions due to loss of H2O, (CH3)4N+ group, SeO2 and finally leaving their corresponding rare earth oxides.

A hydrated double selenate of tetramethylammonium and cobalt(II), [(CH3)4N]2[Co(H2O)6](SeO4)2∙4H2O, was crystalized from aqueous solution under controlled atmosphere and its crystal structure, vibrational properties and thermal stability were investigated by single crystal XRD, FTIR and thermogravimetric studies. Single crystal X-ray diffraction studies revealed an orthorhombic (space group Pca21) lattice with unit cell parameters a = 29.4027(4) A, b = 6.4152(1) A, c = 13.7442(2) A, V = 2592.59(6) A3 and Z = 4, for its crystal structure. The analyses of crystal structure indicated octahedral [Co(H2O)6] 2+ and tetrahedral (CH3)4N+ and SeO42─ entities in it. All these moieties were also confirmed by FTIR spectroscopy. These units are arranged in an open spacious architecture by 3D hydrogen bonding network, and the open spaces are further occupied by additional four water molecules. The stability of the structure is resulted from the though Co–O–H⋯O–Co, Co–O–H⋯O–Se, Se–O⋯H–O–H, H–O–H⋯O hydrogen bonds. The moisture content and temperature of the atmospheric environment were found to be crucial for its crystallization though a reproducible packing of the constituent groups. Thermal analysis (TG-DTG) of the double selenate revealed dehydration and then dissociation into individual salts. Subsequently the loss of organic moiety led to cobalt selenate and finally to cobalt oxide.

Acacia nilotica (babul gum) reinforced with cellulose nanofibers was investigated for a green, biodegradable, and water-soluble nanocomposite. Cellulose nanofibres (CNF) were extracted via a widely accepted steam explosion process and were reinforced in the babul gum. The films were fabricated by solution casting method using sorbitol as a plasticizer. Various concentrations of the CNF reinforced in babul gum exhibited improved properties of mechanical strength, thermal properties, and wetting strength. The lowered hydrophilicity and enhanced mechanical properties will certainly open new doors to explore these nanocomposites for bio-edible coatings and pharmaceutical applications. Furthermore, qualitative and real-life experiments shred light for use in coating applications.

On the reduction of equivalence ratio from stoichiometry to lean conditions, turbulent combustors exhibit intermittency before and after the occurrence of thermoacoustic instability. In this paper, we compare the dynamic characteristics of this intermittency prior to and post thermoacoustic instability. The analysis of the unsteady pressure fluctuations within the combustor suggests that the intermittency prior to and post thermoacoustic instability are of type II. We also compare the flame dynamics during either state using high speed Mie scattering images acquired simultaneously with unsteady pressure. We observe that during both regimes of intermittency, the flame switches between two distinct patterns of oscillations; one where the flame oscillates in an aperiodic manner due to the inherent turbulent fluctuations, and another where the flame exhibits periodic roll-up as a consequence of the periodic vortex shedding at the dump plane. Nevertheless, it is observed that the flame dynamics during intermittency prior to and post the occurrence of thermoacoustic instability are different. During intermittency before the occurrence of thermoacoustic instability, the flame along the inner shear layer is stabilized by the stagnation point flow behind the bluff body. In contrast, during intermittency after the occurrence of thermoacoustic instability, the flame along the inner shear layer is stabilized by the recirculation zone created by the bluff body.

In the past decade, a variety of thermoacoustic engines (TAEs) were devised to convert thermal energy to acoustic power. In this paper, we optimized the design of a standing wave thermoacoustic generator that can provide high intensity acoustic pressure and convert it into electrical power output using a low cost alternator. Three prototypes of standing wave thermoacoustic generator (TAG) were designed to optimize the overall efficiency. The first prototype of standing wave TAG could produce an acoustic pressure of 0.9 kPa (153 dB) with an input thermal power of 210 W. Further, the maximum heat to electrical conversion efficiency was 0.045% with an input thermal power of 250 W. However, the performance of this system was not fully optimized. The performance of TAE depends upon various parameters including stack position, stack length and resonator length. Hence, a new second prototype of tunable TAG was developed to tune these critical parameters in order to improve the overall efficiency. A compact third prototype of TAG was successfully built with optimized parameters and has been tested. In the improved design, high intensity acoustic pressure of 2.9 kPa (163.5 dB) was observed for the same 210 W input thermal power. The maximum heat to electrical energy conversion efficiency was 0.084% with an input of 250 W which is 87% higher as compared to the first prototype. The major reason for the lower conversion efficiency is due to the low efficiency of the alternator. In future, high efficiency alternator designs can be employed along with careful impedance matching to obtain higher conversion efficiencies. The results described in this paper demonstrate the potential of developing compact portable acoustic power and electricity generators for decentralized power applications.

Planetary surface exploration missions are becoming increasingly complex and future missions promise to be even more ambitious than those that have occurred thus far. To deal with this complexity, this paper proposes a fractionated approach to planetary surface exploration. Fractionation involves splitting up large vehicles into several smaller ones that work together in order to achieve the science goals. It is believed that fractionation of rovers can lead to increased value delivery and productivity, as well as helping manage complexity. A science goal-driven methodology for generating a tradespace of multi-vehicle architectures in the early stages of mission design is detailed. A set of carefully designed metrics are then put forward as a way to help compare multi-vehicle architectures to each other and to the single vehicle (monolithic) equivalent. These include science value delivery, productivity, system- and vehicle-level complexity, and mass metrics. Through two Mars-based case studies, the advantages and limitations of fractionation are explored. Fractionation is found to be particularly advantageous when the science goals are broad, when there are competing requirements between goals, and when the exploration environment is particularly treacherous. Additionally, multi-vehicle systems entail simpler vehicles with lower vehicle-level complexity, lower mission risk and higher productivity over the mission duration, as well as being more easily upgradeable. On the other hand, they lead to higher system-level complexity, and can somewhat increase the overall mass of the system. Thus, through this methodology, it was demonstrated that the fractionation of planetary surface exploration systems leads to mass being traded for higher science return and lower risk during the mission, and to complexity being shifted from design complexity to operational complexity. Multi-vehicle systems involve more testing and on-board automation than single vehicles, but they also lend themselves more easily to collaboration between different agencies, and can benefit from several emergent properties that increase the overall functionality of the system.

The crystal structure of CsLn(SeO 4 ) 2 · 4H 2 O ( Ln ≡ La , Pr , Nd or Sm ) was determined using the X-ray powder diffraction technique. A mechanism of thermal dehydration-decomposition was proposed on the basis of thermoanalytical results. The IR spectra of the compounds were scanned in the range 4000 – 200 cm −1 and were interpreted in terms of internal vibrations of the SeO 4 2− tetrahedra.