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Formamidinium lead triiodide (FAPbI3) is the leading candidate for single-junction metal–halide perovskite photovoltaics, despite the metastability of this phase. To enhance its ambient-phase stability and produce world-record photovoltaic efficiencies, methylenediammonium dichloride (MDACl2) has been used as an additive in FAPbI3. MDA2+has been reported as incorporated into the perovskite lattice alongside Cl–. However, the precise function and role of MDA2+remain uncertain. Here, we grow FAPbI3single crystals from a solution containing MDACl2(FAPbI3-M). We demonstrate that FAPbI3-M crystals are stable against transformation to the photoinactive δ-phase for more than one year under ambient conditions. Critically, we reveal that MDA2+is not the direct cause of the enhanced material stability. Instead, MDA2+degrades rapidly to produce ammonium and methaniminium, which subsequently oligomerizes to yield hexamethylenetetramine (HMTA). FAPbI3crystals grown from a solution containing HMTA (FAPbI3-H) replicate the enhanced α-phase stability of FAPbI3-M. However, we further determine that HMTA is unstable in the perovskite precursor solution, where reaction with FA+is possible, leading instead to the formation of tetrahydrotriazinium (THTZ-H+). By a combination of liquid- and solid-state NMR techniques, we show that THTZ-H+is selectively incorporated into the bulk of both FAPbI3-M and FAPbI3-H at ∼0.5 mol % and infer that this addition is responsible for the improved α-phase stability.

Background We conducted this study to compare the weight loss outcome of intragastric balloons (IGBs) in conjunction with pharmacotherapy vs IGB and intensive lifestyle changes alone.Methods This was a multicenter, non-randomized, retrospective study involving 4 academic hospitals. Patients underwent IGB placement with or without concomitant anti-obesity pharmacotherapy. The primary outcome was percent total weight loss (TBWL) after IGB placement at 6 and 12 months.Results This study included 102 patients, with 23 patients (mean age 46.6 years, 82.6% female) treated with IGB/pharmacotherapy and 79 patients (mean age 46.0 years, 88.6% female) treated with IGB/lifestyle modifications. Patients had a 100% follow-up rate at 6 and 12 months. At 6 months following IGB placement, both groups achieved a similar %TBWL. At 12 months, %TBWL was greater in the IGB/pharmacotherapy group (12.6% ± 1.2 vs 9.7% ± 0.7, P= .04). 65.2% of patients achieved ≥10% TBWL at 12 months in the IGB/pharmacotherapy group, compared to 38.0% in the IGB/lifestyle group (P< .05). The proportion of patients that achieved ≥15% weight loss at 12 months was also significantly different between the IGB/pharmacotherapy and IGB/lifestyle groups (30.4% vs 20.3%, P< .05).Discussion IGB with concomitant use of pharmacotherapy did not improve weight loss while the IGB was in place compared to IGB and lifestyle changes. However, patients receiving IGB with pharmacotherapy did have greater weight loss and diminished weight regain after balloon removal compared to those receiving just IGB and lifestyle changes.

Agriculture and industrial wastes (AIWs) have attracted much attention because of their huge environmental, economic, and social impacts. AIWs have been considered a crucial link of a closed-loop for the fabrication of nanomaterials and composites wherein they replace traditional resources with sustainable waste in waste management. In this context, the proper disposal of AIWs is required. This review aims to investigate the technical feasibility of using innovative AIW resources and various strategies for the fabrication of nanomaterials for improving energy applications. First, the utilization of AIWs is classified comprehensively. Second, key technologies to produce nanomaterials are summarized. In addition, this review discusses the potential applications of the fabricated nanomaterials in energy storage and energy conversion.

Emerging climate change mitigation policies focus on the implementation of global measures relying on carbon prices to attain rapid emissions reductions, with limited consideration for the impacts of global policies at local scales. Here, we use the Zambezi Watercourse in southern Africa to demonstrate how local dynamics across interconnected water–energy–food systems are impacted by mitigation policies. Our results indicate that climate change mitigation policies related to land-use change emissions can have negative side effects on local water demands, generating increased risks for failures across all the components of the water–energy–food systems in the Zambezi Watercourse. Analogous vulnerabilities could impact many river basins in southern and western Africa. It is critical to connect global climate change mitigation policies to local dynamics for a better exploration of the full range of possible future scenarios while supporting policy makers in prioritizing sustainable mitigation and adaptation solutions.

This report describes the case of a 32-year-old male presenting with acute progressive bilateral carpal tunnel syndrome after a benign upper respiratory tract infection. Serial nerve conduction studies confirmed progressive [...]

Fully solution-processed, large-area, electrical double-layer transistors (EDLTs) are presented by employing lead sulfide (PbS) colloidal quantum dots (CQDs) as active channels and Ti3C2TxMXene as electrical contacts (including gate, source, and drain). The MXene contacts are successfully patterned by standard photolithography and plasma-etch techniques and integrated with CQD films. The large surface area of CQD film channels is effectively gated by ionic gel, resulting in high performance EDLT devices. A large electron saturation mobility of 3.32 cm2V–1s–1and current modulation of 1.87 × 104operating at low driving gate voltage range of 1.25 V with negligible hysteresis are achieved. The relatively low work function of Ti3C2TxMXene (4.42 eV) compared to vacuum-evaporated noble metals such as Au and Pt makes them a suitable contact material for n-type transport in iodide-capped PbS CQD films with a LUMO level of ∼4.14 eV. Moreover, we demonstrate that the negative surface charges of MXene enhance the accumulation of cations at lower gate bias, achieving a threshold voltage as low as 0.36 V. The current results suggest a promising potential of MXene electrical contacts by exploiting their negative surface charges.

Statin eligibility based on the American College of Cardiology/American Heart Association cholesterol guidelines among patients with diabetes admitted with first time acute myocardial infarction has not been evaluated in the Middle East.

One of the most important part of tissue engineering (TE) is a matrix called scaffold. A good scaffold integrates with the host tissue and support the growth and differentiation of the cells. Collagen is the most abundant protein in the ECM and has been considered to be a group of proteins with a characteristic molecular structure—fibrillar structure, which contributes to the extracellular scaffolding.

Recent advances in solution-processable semiconducting colloidal quantum dots (CQDs) have enabled their use in a range of (opto)electronic devices. In most of these studies, device fabrication relied almost exclusively on thermal annealing to remove organic residues and enhance inter-CQD electronic coupling. Despite its widespread use, however, thermal annealing is a lengthy process, while its effectiveness to eliminate organic residues remains limited. Here, we exploit the use of xenon flash lamp sintering to post-treat solution-deposited layers of lead sulfide (PbS) CQDs and their application in n-channel thin-film transistors (TFTs). The process is simple, fast, and highly scalable and allows for efficient removal of organic residues while preserving both quantum confinement and high channel current modulation. Bottom-gate, top-contact PbS CQD TFTs incorporating SiO2as the gate dielectric exhibit a maximum electron mobility of 0.2 cm2V–1s–1, a value higher than that of control transistors (≈10–2cm2V–1s–1) processed via thermal annealing for 30 min at 120 °C. Replacing SiO2with a polymeric dielectric improves the transistor’s channel interface, leading to a significant increase in electron mobility to 3.7 cm2V–1s–1. The present work highlights the potential of flash lamp annealing as a promising method for the rapid manufacture of PbS CQD-based (opto)electronic devices and circuits.

The Shared Socioeconomic Pathways (SSPs) were developed without explicit assumptions for the future of the water sector; therefore, projections of future water demands based on the SSPs often lack a treatment of water technology assumptions that is consistent with the SSP storylines. This study has developed a set of qualitative and quantitative assumptions for future water sector technological advancements in the agricultural, electricity, manufacturing, and municipal sectors within the SSPs and then applied the resulting scenarios to an integrated assessment model to permit analysis of future water demand in a water‐constrained world. These scenarios are then compared to another set that excludes the adoption of water‐efficient technologies. Water demand impacts of individual SSP assumption categories are analyzed to determine scenario‐by‐scenario changes. By 2100, global annual water demands range from 3,560 to 6,600 km3. The results show that (1) technological change in the water sector can act to reduce water demand in a water limited world by up to 32% in 2100 in the SSP scenarios, (2) the most sustainable scenario produces end‐of‐century water withdrawals lower than 2010 values, (3) low‐income regions will likely be one of the largest drivers of future water demands and exhibit the greatest sensitivity to highly‐efficient water technologies, and (4) nonwater sector SSP assumptions have significant and differing impacts on demands across SSP scenarios that act to alter global water demands. Shared Socioeconomic Pathway qualitative and quantitative model assumptions are expanded to include the water sectorFuture global water demand for all five SSP scenarios is analyzed with and without technological advancements in the water sectorWhere water supplies are constrained, global water demand reductions of up to 32% are possible in SSP scenarios by 2100

Realistic representations of sectoral water withdrawals and consumptive demands and their allocation to surface and groundwater sources are important for improving modeling of the integrated water cycle. To inform future model development, we enhance the representation of water management in a regional Earth system (ES) model with a spatially distributed allocation of sectoral water demands simulated by a regional integrated assessment (IA) model to surface and groundwater systems. The integrated modeling framework (IA‐ES) is evaluated by analyzing the simulated regulated flow and sectoral supply deficit in major hydrologic regions of the conterminous U.S, which differ from ES studies looking at water storage variations. Decreases in historical supply deficit are used as metrics to evaluate IA‐ES model improvement in representating the complex sectoral human activities for assessing future adaptation and mitigation strategies. We also assess the spatial changes in both regulated flow and unmet demands, for irrigation and nonirrigation sectors, resulting from the individual and combined additions of groundwater and return flow modules. Results show that groundwater use has a pronounced regional and sectoral effect by reducing water supply deficit. The effects of sectoral return flow exhibit a clear east‐west contrast in the hydrologic patterns, so the return flow component combined with the IA sectoral demands is a major driver for spatial redistribution of water resources and water deficits in the US. Our analysis highlights the need for spatially distributed sectoral representation of water management to capture the regional differences in interbasin redistribution of water resources and deficits. Pronounced redistribution of water stress driven by spatially distributed sectoral water demands managed through groundwater and return flowEast‐West contrast due to differences in regional sectoral water use, allocation, hydroclimatology, and storage capacity.Sectoral water management is essential for the coupling of integrated assessment models with Earth system models

We perform a quantitative analysis of the trap density of states (trap DOS) in PbS quantum dot field-effect transistors (QD-FETs), which utilize several polymer gate insulators with a wide range of dielectric constants. With increasing gate dielectric constant, we observe increasing trap DOS close to the lowest unoccupied molecular orbital (LUMO) of the QDs. In addition, this increase is also consistently followed by broadening of the trap DOS. We rationalize that the increase and broadening of the spectral trap distribution originate from dipolar disorder as well as polaronic interactions, which are appearing at strong dielectric polarization. Interestingly, the increased polaron-induced traps do not show any negative effect on the charge carrier mobility in our QD devices at the highest applied gate voltage, giving the possibility to fabricate efficient low-voltage QD devices without suppressing carrier transport.

Calcium-activated second messengers such as calciumcalmodulin-dependent protein kinase II have been implicated in drug-induced antinociception. The less abundant calcium-activated second messenger, calciumcalmodulin-dependent protein kinase IV (CaMKIV), mediates emotional responses to pain and tolerance to morphine analgesia but its role in nicotine-mediated antinociception is currently unknown. The goal of this study was to evaluate the role of CaMKIV in the acute effects of nicotine, primarily acute nicotine-induced antinociception. CaMKIVknockout (−−), heterozygote (−), and wild-type () mice were injected with various doses of nicotine and evaluated in a battery of tests, including the tail-flick and hot-plate tests for antinociception, body temperature, and locomotor activity. Our results show a genotype-dependent reduction in tail-flick and hot-plate latency in CaMKIV(−) and (−−) mice after acute nicotine treatment, whereas no difference was observed between genotypes in the body temperature and locomotor activity assessments. The results of this study support a role for CaMKIV in acute nicotine-induced spinal and supraspinal pain mechanisms, and further implicate involvement of calcium-dependent mechanisms in drug-induced antinociception.

Agricultural nonpoint source pollution has been identified as one of the leading causes of surface water quality impairment in the United States. Such an impact is important, particularly in predominantly agricultural areas, where application of agricultural fertilizers often results in excessive nitrate levels in streams and rivers. When nitrate concentration in a public water supply reaches or exceeds drinking water standards, costly measures such as well closure or water treatment have to be considered. Thus, having accurate nitrate-N predictions is critical in making correct and timely management decisions. This study applied a set of data mining tools to predict weekly nitrate-N concentrations at a gauging station on the Sangamon River near Decatur, Illinois. The data mining tools used in this study included artificial neural networks, evolutionary polynomial regression and the naive Bayes model. The results were compared using seven forecast measures. In general, all models performed reasonably well, but not all achieved best scores in each of the measures, suggesting that a multi-tool approach is needed. In addition to improving forecast accuracy compared with previous studies, the tools described in this study demonstrated potential for application in error analysis, input selection and ranking of explanatory variables, thereby designing cost-effective monitoring networks. [ABSTRACT FROM AUTHOR]

The market share of wrought Magnesium products such as structural and functional components is recently increasing. Extrusion at elevated temperatures is used to produce reliable plastic deformation, since magnesium alloys have limited ductility at room temperature. In order to produce sound extruded products, high quality billets are required. Understanding the influence of direct chill casting conditions on the production properties such as quality, safety, workability and microstructure have a profound importance. Comprehensive computer simulations were used in order to model the casting so that process parameters can be identified and controlled, resulting in significant benefits. The aim of modeling is to provide temperature profiles for a more accurate solidification analysis, predict the solidification time and the effect of cooling on the solidification. The experimental study included castings of several Magnesium alloys, each with 7 (seven) thermocouples that were submerged into the billet. Verification of the simulations was carried out based on the data collected. Complimentary work was conducted on microstructure analysis in as cast and as-extruded states.

The high temperature response in torsion and creep of two extruded Mg-Zn alloys was investigated in the present study. The alloy 0 (Mg-2Zn-1Mn) was found to exhibit a lower strength than the alloy 2 (Mg-0.55Zn-0.79Mn-0.75Al-0.17Ca), even if the activation energy for creep was similar for both materials (170-180 kJ/mol). The difference in flow stress was here preliminarily attributed to the precipitation of fine Al2Ca particles.

A 12-year-old Congolese girl presented with acute renal failure, edema, hypertension, hemoptysis, hematuria, and proteinuria after a history of throat infection. Renal ultrasound showed kidneys of normal size, with increased echogenicity of the cortical parenchyma and decreased corticomedullary differentiation. Other additional investigations showed pancytopenia with decreased complement (low C3 and C4). Antinuclear antibodies were strongly positive, including anti-double stranded DNA. Renal biopsy confirmed severe grade IV lupus nephritis. She was treated with high-dose steroids, mycophenolate mofetil and hydroxychloroquine, in addition to hemodialysis. After one week of intensive treatment, diuresis recovered and dialysis could be stopped after six sessions. We describe an uncommon case of severe lupus nephritis, presenting with terminal renal failure. Since the rarity of this disease presentation, other more common diagnoses have to be considered. Once the diagnosis of lupus nephritis is established, a choice has to be made between the different induction treatment protocols. The patient’s ethnic background and other supportive therapies, such as the need for dialysis, can help to make this choice.

We calibrate a storm-event distributed hydrologic model to a watershed, in which runoff is significantly affected by reservoir storage and release, using a multi-objective genetic algorithm (NSGA-II). This paper addresses the following questions: What forms of the objective (fitness) function used in the optimization model will result in a better calibration? How does the error in reservoir release caused by neglected human interference or the imprecise storage-release function affect the calibration? Reservoir release is studied as a specific (and popular) form of human interference. Two procedures for handling reservoir releases are tested and compared: (1) treating reservoir releases to be solely determined by the hydraulic structure (predefined storage or stage-discharge relations) as if perfect, a procedure usually adopted in watershed model calibration; or (2) adding reservoir releases that are determined by the storage-discharge relation to an error term. The error term encompasses a time-variant human interference and a discharge function error, and is determined through an optimization-based calibration procedure. It is found that the calibration procedure with consideration of human interference not only results in a better match of modeled and observed hydrograph, but also more reasonable model parameters in terms of their spatial distribution and the robustness of the parameter values. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effectiveness of slow deep breathing relaxation exercise (SDBRE) in reducing patients’ pain levels during chest tube removal (CTR) post coronary artery bypass grafting (CABG) surgery.

The potential of furnace techniques and of laser evaporation for the analysis of dry solution residues and of solids by different atomic emission procedures is described. The new one-step FANES technique (furnace atomic nonthermal emission spectrometry) is compared with the two-step procedure ETV-ICP-AES (electrothermal vaporisation—inductively coupled plasma—atomic emission spectrometry). In case of dry solution residues the sensitivity of the FANES is higher (1–2 orders of magnitude) as a result of better discharge conditions (low background) and direct sample introduction, particularly for volatile and moderately volatile substances. For refractory elements the higher gas temperature of the ICP plasma causes better atomisation, which can lead to higher sensitivity of the ETV-ICP-AES. A new Laser-FANES hybride technique is introduced for microanalysis in solid samples and compared with Laser-ICP-AES. The Laser-FANES is shown to combine the advantages of Laser-ETA-AAS (high sensitivity) and of Laser-ICP-AES (multielemental determinations), particularly for volatile and moderately volatile elements.

Social norms, the often unspoken rules that dictate behavior, are increasingly understood to play a role in child, early and forced marriage (CEFM) practices, but are less frequently examined in quantitative research on CEFM. No research on this topic has focused on Niger, despite the country having the highest prevalence of child marriage in the world. This study examines the associations of community and individual-level norms on marital age and marital choice with the outcomes of girls' age at marriage and choice in marriage. We used data from a family planning evaluation trial conducted in three districts within the Dosso region of Niger. Survey data were collected from adolescent wives and their husbands (N = 582) on demographics, normative beliefs regarding girls' age at marriage and marital choice, and among wives, age at marriage and engagement in marital choice. We developed our community-level norm variables by using the aggregate data from husbands' and wives' norms and wives' CEFM experiences. Using crude and adjusted regression models, we assessed the associations between our norms variables and our CEFM outcomes. In this context of very high prevalence of CEFM, we found that village-level norms related to marital choice, particularly the norms of men, are associated with younger age of girls at marriage. We also found that younger age of girls at marriage is positively associated with lower likelihood of their engagement in marital choice. Further, we find that village-level norms related to a later age of marriage and support for marital choice, as well as adolescent wives' perceptions of community norms related to a higher age of marriage, are associated with higher odds of a wife having had marital choice. These findings suggest the value of community level social norms change on CEFM in Niger, and the importance of focusing on child marriage and girls’ marital choice simultaneously given their interconnection.

Climate change is projected to elevate stream temperature and poses threats to thermoelectric power generation. Although two thirds of the global rivers are regulated by dams, the impacts of river regulation on stream temperature and thermoelectricity production have not been evaluated in previous studies. Using a state‐of‐the‐art integrated water cycle model and a power generation model, we quantify the impacts of river regulation on stream temperature and usable capacity of once‐through thermoelectric power in the United States. Our study demonstrates that by lowering stream temperature and increasing water availability during the low‐flow season, river regulation can curtail the loss of summer power plant usable capacity induced by climate change. The alleviation of power loss by water management is comparable to that resulting from emission mitigation that reduces warming in the future. Our new findings highlight the necessity of incorporating water management effects in thermoelectric power vulnerability assessment. The relative impacts of climate change and river regulation on stream temperature and thermoelectric power generation are quantifiedRiver regulation can mitigate stream temperature warming through temporal and spatial redistribution of streamflowRiver regulation alleviates power plant usable capacity loss from climate change by as much as the effect from emission mitigation

The earthquake may cause many deaths and injuries and extensive property damage and dramatically change the geographic structure of the impacted area. Vulnerability in the context of building structure can be defined as inability to resist the earthquake loadings and unfortunately the majority of existing buildings in Ranau Township were built consequently without seismic consideration. The rapid development had increased the probability of building damages due to the earthquake activities that appeared around the area since. This study aims to identify, evaluate buildings and calculated vulnerability using the Rapid Visual Screening (RVS) method through the framework of Geographic Information System (GIS). The results of this study revealed that from 245 buildings, the damage level for 21 buildings were in grade 3, 11 buildings under grade 2 and other buildings in grade 1 i.e. heavy, moderate and little damages, respectively. After knowing the vulnerability level of buildings, the developer may do an early prevention to avoid further damages due to earthquakes in the future. This method can be used in moderate seismicity region such as Sabah as an early detection for building vulnerabilities.

Reservoir storage‐area‐depth relationships are the most important factors controlling thermal stratification in reservoirs and, more broadly, the water, energy, and biogeochemical dynamics in the reservoirs and subsequently their impacts on downstream rivers. However, most land surface or Earth system models do not account for the gradual changes of reservoir surface area and storage with the changing depth, inhibiting a consistent and accurate representation of mass, energy, and biogeochemical balances in reservoirs. Here we present a physically coherent parameterization of reservoir storage‐area‐depth data set at the global scale. For each reservoir, the storage‐area‐depth relationships were derived from an optimal geometric shape selected iteratively from five possible regular geometric shapes that minimize the error of total storage and surface area estimation. We applied this algorithm to over 6,800 reservoirs included in the Global Reservoir and Dam database. The relative error between the estimated and observed total storage is no more than 5% and 50% for 66% and 99% of all Global Reservoir and Dam reservoirs, respectively. More importantly, the storage‐depth profiles derived from the approximated reservoir geometry compared well with remote sensing based estimation at 40 major reservoirs from previous studies and ground‐truth measurements for 34 reservoirs in the United States and China. The new global reservoir storage‐area‐depth data set is critical for advancing future modeling and understanding of reservoir processes and subsequent effects on the terrestrial hydrological, ecological, and biogeochemical cycles at the regional and global scales. This study developed the first global reservoir storage‐area‐depth database for physically based reservoir modeling at regional or global scalesDerived using mathematical approximation and data from GRanD, the relative storage error for most of the 6,824 global reservoirs is less than 25%The new database has been successfully validated against remote sensing and ground‐truth observations from 74 reservoirs

Dye sensitized solar cell has been emerged as one of the most promising candidates for photovoltaics applications in good quality of their low manufacturing cost and impressive conversion energy. Titanium dioxide (TiO2) which is used as photoanode in the market has the advantage of wide bandgap energy but low in electron mobility ([?]10 cm2/(V.s)). Ruthenium in the other hand, as the dye sensitizer is a rare noble metal and harmful to human health. Thus, this article reveals the performance of photo-to-electric conversion efficiency with the usage of Zinc Oxide as photoanode with higher electron mobility (155 cm2/(V.s)) compared to TiO2 utilizing three natural fruit dyes of Prunus domestica, Magnifera indica and Citrus limon. ZnO and TiO2 photoanodes were fabricated using sol gel and dr blade method respectively. The morphology of the photoanodes were characterized using Scanning Electron Microscope and the efficiency of the complete DSSC with all different fruit dyes were characterized using Semiconductor Parametric Analyzer. The different property of electron mobility photoanodes effect in DSSC proved to give better performance with the photoconversion efficiency of 3.082% using ZnO with Prunus domestica dye. This article also reveals that pH indicator does not affect the selection and the performance of DSSC.

Ga1-xInxP composition has been applied to the top cell of multi-junction GaInP/GaAs based solar cell and currently have achieving a conversion efficiency of more than 46%, however its capability is unclear. We performed an analysis using Silvaco simulation method to evaluate the effect of In and the substitution was made to the Ga1-xInxP for the range of x from 0 to 1. We found that the highest efficiency recorded was 17.66% when the composition of Indium was x=1. The efficiency has been increasing about 11.71% from x=0 to x=1 In content. As the composition of In raised, the value of efficiency and short circuit current density, Jsc also become higher (13.60 mA/cm2) by having a greater photon absorption in a wider band gap energy. In addition to that, Voc, Pmax, Vmax, Imax and fill factor was measured to be 2.15 V, 2.44 mW/cm2, 2.0 V, 1.22 mA/cm2 and 83.34 respectively. In conclusion, this study confirms that the existence of In in Ga1-xInxP improves the solar cell efficiency by gaining a higher energy gap and producing more electrons for best achievement in multilayer solar cell applications.

The gold standard treatment for pain after cesarean delivery is subarachnoid morphine (SAM). Use of morphine, however, is associated with a number of adverse effects and with medical contraindications and logistic issues that limit its use. An effective alternative is ultrasound-guided transversus abdominis plane (TAP) block. This treatment method provides real-time imaging of the needle trajectory and injectate spread, and may improve both safety and nerve block effectiveness. SAM not only has a longer duration of effective pain relief as compared with TAP block, but also relieves abdominal wall-derived pain, and unlike TAP block, relieves visceral pain from the uterus.

As the spontaneous polaristion in a ferroelectric is reversed by an applied electric field, short duration ultrasonic signals are produced which degrade into the geometric normal vibrational resonance modes of the crystal. Simultaneous visual observation and monitoring of the ultrasonic signals show that these acoustic emissions produced as Pb5Ge3O11 and Gd2 (MoO4)3 are taken round the hystresis loop result from domain wall nucleation and collapse.