Melting Profiles Research Articles

Evaluation of High-Resolution Melting for Rapid Differentiation of Phytophthora Hybrids and Their Parental Species.

Phytophthora species hybrids have been repeatedly reported as causing damaging diseases to cultivated and wild plants. Two known hybrids, P. andina and P. × pelgrandis, are pathogens of Solanaceae and ornamentals, respectively, although the extent of their host ranges are unknown. P. andina emerged from hybridization of P. infestans and an unidentified related species, whereas P. × pelgrandis emerged from P. nicotianae and P. cactorum. Considering that hybrids and parental species can coexist in the same regions and to distinguish them usually requires cloning or whole genome sequencing, we aimed to develop a rapid tool to distinguish them. Specifically, we used high-resolution melting (HRM) assays to differentiate genotypes based on their amplicon melting profiles. We designed primers for P. × pelgrandis and parental species based on available sequences of P. nicotianae and P. cactorum nuclear genes containing polymorphisms between species. For P. andina, heterozygous sites from Illumina short reads were used for the same purpose. We identified multiple amplicons exhibiting differences in melting curves between parental species and hybrids. We propose HRM as a rapid method for differentiation of P. andina and P. × pelgrandis hybrids from parental species that could be employed to advance research on these pathogens.

Characterization of different ozonized sunflower oils II. Triacylglycerol condensation and physical properties

Within the chemical transformations that vegetable oils undergo, oxidative reactions are one of the most widely studied. During the process of oxidation oils react with oxygen in their different forms to produce a large variety of chemical species that alter their chemical and physical properties. This work is the second of a series of two in which the action of ozone on different sunflower oils was investigated. Ozone reacts with double bonds of unsaturated fatty acids which produce different peroxidated species. The presence of altered triacylglycerol (TAG) increases the polarity of the vegetable oils and induces changes in their physical properties. Moreover, peroxygenation alters the aggregation of TAGs, favoring the formation of dimers or oligomers that can substantially change the melting and crystallization profiles of these oils. In the present work the effect of ozonation on four different sunflower oils was studied: common sunflower, high oleic sunflower and two highly saturated sunflower oils, high palmitic and stearic in a high oleic background. Furthermore, the species of TAGs from the different oils that were affected by the ozone oxidative attack were studied. The formation of polar compounds and TAG aggregates were investigated as well as the effect caused by them on the physical properties of the oils as studied through differential scanning calorimetry.

Thermal and mechanical properties of industrial benchmark lipstick prototypes

We studied the thermomechanical properties of eight original, industrial-grade, and commercially available benchmark lipstick prototypes, some of which serve as international market leaders. The thermal properties, i.e., the melting peak distribution, the degree of crystallization, and the softening point, were investigated using differential scanning calorimetry. Additionally, we investigated the linear and nonlinear viscoelastic properties as well as the flow melting behavior under oscillatory shear stresses. We recorded both polymorphic melting profiles with multiple, narrow as well as single, broad melting peaks. Stable networks, less endothermic events, and a more desired extent of crystallinity validate the market popularity of some of the benchmark prototypes. We observed a prototype-dependent resistance to the deforming strain and temperature, decent short-term mechanical stability, intercycle strain thinning of both dynamic moduli at high strain amplitudes, and predominant elasticity at quasi-steady state. The temperature sweeps mainly indicated gel-like behavior. This study has both fundamental and application-oriented aspects. Namely, in addition to establishing thermomechanical reference values, we discuss them from a textural perspective and relate them to different consumer groups. Besides, we reveal the full mechanical continuum under low to high strains, give the strain tolerance limits, and present innovative concepts like the intrinsic sample elasticity. The results of this study can guide the development of next-generation lipsticks, including natural component-based samples with active ingredients.

Effect of Accelerated Storage on Fatty Acids, Thermal Properties and Bioactive Compounds of Kenaf Seed Oil.

The effects of thermal oxidation at 65 °C for 24 days on oxidation indices, fatty acid positional distribution, thermal properties, vitamin E composition and sterol composition of kenaf seed oil are investigated. The results showed that total oxidation value (TOTOX) of the oil increased from initial 8.83 to 130.74 at the end of 24 days storage. Linoleic acid at sn-1, 3 positon of kenaf seed oil was less stable than the one at sn-2 positon. Oxidative degradation changed the melting profile of kenaf seed oil, the value of endothermic enthalpy reduced from 58.17 to 20.25 J/g after 24 days of storage. Moreover, the content of vitamin E and total sterol decreased by 84.26% and 38.47%, respectively. Tocotrienols were more stable than tocopherols during the accelerated storage. Correlation analysis indicated vitamin E content was significantly related to p-anisidine value, while sterol content was significantly related to peroxide value. PRACTICAL APPLICATION: Kenaf seed oil is rich in polyunsaturated fatty acids and bioactive compounds. Heating process and long-term storage cause oil oxidation and bioactive compounds degradation. The oxidation process of kenaf seed oil is simulated with accelerated storage. The study evaluates fatty acid composition and distribution, vitamin E and sterol content, melting thermal characteristics of kenaf seed oil at different oxidation levels. The research shows the stability of fatty acid is related with its type and position in backbone of triacylglycerol molecule. There are good correlation among oxidation level, vitamin E and sterol content, and melting enthalpy value of kenaf seed oil.

Effect of allotypic variation of human IgG1 on the thermal stability of disulfide-linked knobs-into-holes mutants of the Fc for stable bispecific antibody design.

BackgroundDisulfide-linked knobs-into-holes (dKiH) mutation is a well-validated antibody engineering technique to force heterodimer formation of different Fcs for efficient production of bispecific antibodies. An artificial disulfide bond is created between mutated cysteine residues in CH3 domain of human IgG1 Fc whose positions are 354 of the “knob” and 349 of the “hole” heavy chains. The disulfide bond is located adjacent to the exposed loop with allotypic variations at positions 356 and 358. Effects of the variation on the biophysical property of the Fc protein with dKiH mutations have not been reported.MethodsWe produced dKiH Fc proteins of high purity by affinity-tag fusion to the hole chain and IdeS treatment, which enabled removal of mispaired side products. Thermal stability was analyzed in a differential scanning calorimetry instrument.ResultsWe firstly analyzed the effect of the difference in allotypes of the Fcs on the thermal stability of the heterodimeric Fc. We observed different melting profiles of the two allotypes (G1m1 and nG1m1) showing slightly higher melting temperature of G1m1 than nG1m1. Additionally, we showed different characteristics among heterodimers with different combinations of the allotypes in knob and hole chains.ConclusionAllotypic variations affected melting profiles of dKiH Fc proteins possibly with larger contribution of variations adjacent to the disulfide linkage.

Stability of DNA passing through different geometrical pores

The recent years witnessed significant advances in nanopore technology and the DNA sequencing. One of the efficient methods for DNA sequencing is denaturation mapping of the DNA molecule that is trapped inside a cylindrical geometry. In this paper, we investigate the denaturation of homogeneous as well as heterogeneous DNA molecules which are confined in a conical as well as cylindrical geometric space. For the conically shaped confinement, we study the effect of the cone angle and the pore width on the melting profile of homogeneous DNA molecules. Similarly, for the cylindrically shaped confinement, we investigate the effect of the cylinder diameter on the melting profile of homogeneous and heterogeneous DNA molecules. We consider the conditions when DNA is partially inside the confined space and partially outside the confined space. For the investigation, we vary the fraction of base pairs that remains inside the space and calculate the denaturation profile of DNA molecules in each condition.

High-resolution melting of multiple barcode amplicons for plant species authentication

In recent years, species identification in herbs has attracted considerable attention due to several cases of fraud; hence inexpensive high-throughput authentication methods are highly welcomed. Species authentication is often performed through DNA analysis and several specific regions (barcodes) are considered suitable. Each barcode (Bar) possesses different qualities in terms of universality and discrimination power. A multiplexed format where information can be extracted simultaneously from several barcode regions is seemingly appropriate to ensure the power of both universality and discrimination. In this approach, we amplified DNA from five different barcode regions in a multiplexed PCR format followed by high-resolution melting (HRM). This multiplexed Bar-HRM approach was first applied to plants spanning the plant kingdom and then gradually narrowing down the genetic variability within the Lamiaceae and the Solanaceae families to finally reach closely related cultivars. Universality was demonstrated through distinct melting profiles obtained for species originating from 29 different families spanning the angiosperms, gymnosperm, mosses, and liverwort (Marchantiophyta). Discrimination power was retained for species, sub-species, and a few cultivars through the application of multivariate statistics to the high-resolution melting profiles. This preliminary investigation has shown the potential to discriminate a vast amount of species within the whole plant kingdom. It requires no a priori knowledge of the species' DNA sequence and occurs in a closed system within 2.5 h at a reduced cost per sample compared to other DNA based approaches.

Prediction of Melting Profile of Mild Steel Weld Metals Using Regression Analysis

The microstructure of a weldment can be maintained by ensuring a steady state homogenous melting profile of the welding operation, which includes the deposition of optimum volumes of melted filler wire and substantial part of the heat affected zones of the parent metal to form the weld pool. The melting pattern of the entire welding process should be protected from atmospheric air, so as to enhance weldment quality. In this study, the melting profile of mild steel is investigated by looking at the parent metal angular distortion bead width and penetration volumes of deposited filler and the melting efficiency was determined. Predictive models were also developed to determine the above listed melting properties by applying the regression analysis. The result obtained showed that, there is almost a perfect fit between the calculated and predicted angular distortion, as well as between the calculated and predicted volume of filler wire melted. There is also a close correlation between the calculated and predicted melting efficiency. However, for the bead width, bead penetration and volume of weld metal deposited, there were variations of values and a heterogeneous correlation between the calculated, measured and predicted values. The effects of the process parameters on the obtained properties of the melting profile were investigated and optimum process parameters were determined.

Composition and thermal characteristics of seed oil obtained from Chinese amaranth

Amaranthus tricolor and Amaranthus dubius are the most prevalent vegetable amaranths in China. The fatty acid composition, triacylglycerol (TAG) profile, vitamin E and sterol content, and thermal properties of seed oils extracted from these two vegetable amaranths were investigated in this work. The results reveal that the seed contains ∼8% oil. The main fatty acids in the oils are linoleic (51.5–53.5%), oleic (14.8–18.4%), palmitic (15.7–17.1%) and stearic (3.6–4.1%). PLL (∼22%), LLL (∼20%), LLO (∼17%) and POL (∼11%) are the dominant TAGs in the oils. The amaranth seed oils exhibit a distinct melting and crystallization profile that consists of 5 endothermic peaks and 2 exothermic peaks. The oils are rich in vitamin E (705–829 mg/kg) with δ-tocopherol as the major component. The two oils have similar total sterol contents (2488.7 and 2762.1 mg/100 g) but different individual sterol percentages. The higher contents of oil, linoleic acid, vitamin E, and sterols make the amaranth seed oil desirable in terms of nutrition.

Influence of Geographic Region on Fatty Acid and Physical Properties of Indonesian Cocoa Butter from Smallholder Estate


 
 
 Cocoa butter is the most essensial component in chocolate formulation and represent the biggest characteristic of this product. Indonesia is the third cocoa producers with cocoa producing area spread out in different geographic region and may affect in cocoa butter profiles. The aim of this experiment was to evaluate the fatty acid characteristic and physical properties of cocoa butter from smallholder estate relate to geographic region and climate. This experiment was conducted using unfermented cocoa bean from smallholder estate in eight provinces of Indonesian most growing areas. Fatty acid composition evaluated through the different region and physical properties evaluated in melting profiles and solid fat content. The result explain the fatty acid characteristic of Indonesian cocoa butter consist of palmitic acid (C16:0) 26.28–29.20%, stearic acid (C18:0) 32,14–37.29% and oleic acid (C18:1) 32,14–37,29%. Growing temperature signifi- cantly affects the increase of palmitic acid composition contribute to cocoa butter hardness. Cocoa butter completely melt in temperature of 36.65–39.20OC and solid fat content ranged 7.288–16.82% in 33OC and ranged 0.02–0.29% in 38OC. This Indonesian cocoa butter comply to the classification of hard cocoa butter.
 
 

In vitro chondroprotective potential of Senna alata and Senna tora in porcine cartilage explants and their species differentiation by DNA barcoding-high resolution melting (Bar-HRM) analysis.

Senna species and anthraquinone derivatives generated by these organisms, rhein and aloe-emodin, exert anti-inflammatory effects. These species present a similar morphology but produce different ingredients when they are used as medicinal products. In this study, a DNA barcoding- (Bar-) high-resolution melting (HRM) technique was developed using internal transcribed sequence 2 (ITS2) to differentiate between Senna alata and Senna tora as a result of significant differences in their melting profiles. We used this approach for confirmation of S. alata and S. tora raw materials, and we examined the chondroprotective properties of the ethanolic extracts of S. alata and S. tora using a porcine model of cartilage degradation induced by a combination of interleukin-17A (IL-17A) and IL-1β. We found that both Senna ethanolic extracts, at a concentration of 25 μg/mL, effectively prevented cartilage degradation. Rhein and aloe-emodin were present in the extract of S. alata but not in that of S. tora. We observed a reduction in the release of sulfated glycosaminoglycans (S-GAGs) and hyaluronic acid (HA) into media in both treatments of Senna extracts, which indicated proteoglycan preservation in explant tissues. These results suggest that neither rhein nor aloe-emodin are the main factors responsible for cartilage-protecting properties. Taken together, results show that both S. alata and S. tora are promising for further development as anti-osteoarthritic agents and that Bar-HRM using ITS2 could be applied for species confirmation with Senna products.

Use of High‐Intensity Ultrasound to Change the Physical Properties of Oleogels and Emulsion Gels

AbstractThe objective of this work was to evaluate the effect of high‐intensity ultrasound (HIU) on the physical properties of a soft oleogel (2% of candelilla wax, 2% of monoacylglycerol, and 2% of hardfat) and of water‐in‐oil (W/O) emulsion gels (EG) with various amounts of water (0%, 5%, and 25%). Physical properties of these systems such as thermoresistance, microstructure, melting profile, hardness, rheology, and oil loss were measured. When HIU was applied to the oleogel for 3 min using a 3.2 mm‐diameter tip at an amplitude of vibration of 216 μm, a reduction in crystal size and crystal area (P < 0.05) was observed with an increase in hardness and no change in G′ nor in oil loss compared to the nonsonicated oleogel. Other sonication conditions (lower power levels, shorter durations, and bigger tips) tested in this study reduced the hardness and elasticity of the sample and increased oil loss. When HIU (3.2 mm‐diameter tip, 216 μm, 3 min) was used in emulsions, harder and more elastic (P < 0.05) samples were obtained only in the samples with 25% water. This study shows that the texture of oleogels and EG with 25% of water can be improved by using HIU. The impact of these results is that the fat content of an EG can be reduced by 25% by adding water and HIU can be used to recover the structure lost due to water addition.

The comparison of two whole genome amplification methods: A new method of pre-implantation genetic testing (PGT-M) for Southeast Asian deletion in alpha-thalassemia using high resolution melting analysis

Introduction In Southeast Asia, alpha-thalassemia with Southeast Asian (SEA) deletion type is the most common mutations of alpha-thalassemia-1 which can cause severe form known as Bart's hydrops fetalis. For couples which carrier of single gene defects, pre-implantation genetic testing for monogenic (PGT-M) plays a role in genetic testing for selecting of unaffected embryos prior implantation. Recently, high resolution melting (HRM) analysis is a simple, rapid and widely used for genotyping and gene scanning of genetic variation. In this study, we developed HRM analysis method for detection of SEA deletion in alpha-thalassemia and compared two WGA methods, SurePlex DNA Amplification System and REPLI-g Single Cell on the performance of HRM analysis and linkage analysis. Material and Methods Retrospective study was carried out in a single private fertility clinic from 2015 to 2017. The single cell embryos were biopsied on blastocyst stage from couples with disease- carrier of SEA deletion type. The trophectoderm biopsied cells were amplified by two whole genome amplification (WGA), SurePlex DNA Amplification System-PCR based method (Illumina, USA) and REPLI-g MDA Single Cell (QIAGEN, Germany). All WGA products were analyzed with two primer pairs of HRM analysis for detection of SEA deletion type in alpha-thalassemia disease and confirmed with the informative short tandem repeated (STRs) linkage analysis. Results A total of 53 single cell biopsied were amplified with SurePlex-WGA (n=33) and REPLI-g MDA (n=20) which used as template for HRM analysis. The HRM results revealed clearly distinguished between wild type and mutant type of SEA deletion mutation in alpha-thalassemia. Comparing between two WGA methods, the HRM amplification results efficiency and allele drop out (ADO) rate of REPLI- g MDA were 95% (19/20) and 31.57% (6/19), respectively. Meanwhile, for SurePlex-WGA showed 75.76% (25/33) and 28% (7/25), respectively. Furthermore, the HRM melting profile results of REPLI-g MDA showed higher concordance rate with the informative STRs linkage analysis results (63.16%, 12/18) than that of SurePlex-WGA (48%, 12/25). Conclusions HRM analysis is an alternative technique with high sensitivity and accuracy for detecting of alpha-thalassemia mutations. The REPLI-g MDA Single Cell method with HRM analysis is suitable for detection of alpha-thalassemia1 SEA type deletion in PGT-M and provided a good concordance with informative STRs linkage analysis. However, ADO from PCR amplification could be occurred and caused of misdiagnosis which might be affected to the interpretation results of the embryos disease- status. Thus, the mutation analysis method using HRM analysis combined with STRs linkage analysis are recommend in PGT-M to avoid the effected of ADO and increase the accuracy and reliable of the PGT-M results.

Practical Determination of Solid Fat Content in Fats and Oils by Single-Wavelength Near-Infrared Analysis

The melting profile of solid fat content (SFC) is an important parameter for many fat-based food products, such as solid matrices, emulsions, and dispersions, since it can provide essential information on product stability, physical appearance, spreadability, mouthfeeling, particles adsorption and coalescence, and on the release of compounds in the encapsulation technology. The current standard techniques to measure SFC, namely, pulsed nuclear magnetic resonance and differential scanning calorimetry (DSC), provide accurate results but require expensive instrumentation and trained personnel. On the other hand, techniques are needed for fast, in situ measurements by generic operators along production lines to control industrial processes. In this paper, a novel technique to measure SFC in vegetable fats and oils is presented that could be implemented in the form of a low-cost, portable electronic system. The method is based on single-wavelength (835 nm) optical measurements during a thermal cycle of the sample under test. The experimental results obtained with such a method are in good/excellent agreement with those provided by DSC ( $R^{2} > 0.9$ ), thus indicating that the proposed technique could represent the basis for practical analysis in production environment, in order to evaluate the quality and the properties of liquid and solid fat food materials.

An experimental and numerical study on the effect of inclination angle of phase change materials thermal energy storage system

Abstract The main purpose of the present study is to investigate the melting characteristics of a PCM cylindrical thermal storage system using experimental and numerical approaches. Three inclination positions are considered from vertical to horizontal. Paraffin wax has been used as the phase change material with a melting temperature ranged between 35 and 37 oC. The melting behaviour of the PCM inside the storage is characterised using different parameters of temperature distribution, imaging of PCM melting profiles, rate of stored heat, and liquid PCM flow within the storage. The results show that the PCM storage inclination angle has a significant effect on the PCM temperature distribution, PCM melting time and profile. It is noted that PCM in the storage in the 45° inclination angle from the horizontal location has the fastest melting rate is the fastest in melting compared to the 0° and 90° inclination angles. The simulation models enable understanding the internal flow of liquid PCM where it has been found that the direction of buoyant force resulting from the melted liquid PCM has a major role in both melting rate and melting direction within the PCM storage. In addition, it has been observed that the charging rate has no effect on the PCM melting profile.

Covalently Palladated Oligonucleotides Through Oxidative Addition of Pd0.

An 11-mer oligonucleotide incorporating a central (2-iodobenzoylamino)methyl residue has been synthesized and palladated by oxidative addition of Pd2 (dba)3 . UV melting profiles of the duplexes formed by the palladated oligonucleotide with its natural complements were biphasic and the higher melting temperatures (Tm ) exhibited considerable hysteresis. CD spectra, in turn, resembled those of canonical B-type double helices. Two-step denaturation, with the "low-Tm " melting involving only canonical base pairs and the "high-Tm " melting involving also dissociation of a PdII -mediated base pair, appears the most likely explanation for the observed UV melting profiles. As the latter step in all cases takes place at a higher temperature than denaturation of natural duplexes of the same length, the putative PdII -mediated base pairs are stabilizing.

Carrier screening for spinal muscular atrophy with a simple test based on melting analysis.

Carrier screening of spinal muscular atrophy (SMA) can provide reproductive options for carriers and prevent the birth defects. Here, we developed a simple screening test based on melting analysis. The test comprises a duplex PCR with two primer pairs and three probes to simultaneous amplify SMN1, SMN2, and CFTR. By analyzing the melting profiles, we were able to determine the SMN1/SMN2 ratio and SMN1 + SMN2 copy number to subsequently determine the copy number of SMN1. Samples with one copy of SMN1 were considered as "high risk for carrier," while samples with ≥2 copies of SMN1 were considered as "low risk for carrier." We evaluated the clinical performance of this test using 215 clinical samples with various genotypes that had been previously confirmed by multiplex ligation-dependent probe amplification (MLPA). The test showed high sensitivity (100%) and specificity (97.1%) as well as high positive (97.3%) and negative (100%) predictive value, and was in perfect agreement with the gold standard test, MLPA (k = 0.97). Moreover, it is rapid, inexpensive, and easy to perform and automate, with high reproducibility and capacity. Therefore, we expect this test will advance carrier screening for SMA.

Host and pathogen factors in Klebsiella pneumoniae upper urinary tract infections in renal transplant patients.

To analyse the role of virulence factors (VFs) and host in Klebsiella pneumoniae upper urinary tract infections (UTIs) in renal transplant (RTx) recipients. Clinical and demographic data were registered prospectively. Phylogenetic background of K. pneumoniae isolates was analysed by PCR melting profiles (MP) and the following VFs genes: fimH-1, uge, kpn, ycfM, mrkD, rmpA, magA, hlyA, cnf-1, irp-1, irp-2, fyuA, entB, iutA, iroN by PCR. We studied urine cultures and clinical data from 61 episodes of K. pneumoniae UTI in 54 RTx recipients. There were 32 cases of AB (53%), 10 cases of lower UTI (16%), 19 cases of AGPN (31%), including six cases of bacteraemia. In total, 74 % of strains were extended-spectrum beta-lactamase+, and there were two carbapenemase-producing strains. PCR MP typing showed a diverse population with 52 different genetic profiles of K. pneumoniae. Analysis of the DNA profiles indicated 45 unrelated, unique genotypes and 7 related (16 isolates from 15 patients) genotypes. Urine flow impairment emerged as an independent predictor of K. pneumoniae upper UTIs (OR 14.28, CI 2.7-75.56, P 0.002), while we did not find any association between the profile of VFs and developing upper UTIs. The prevalence of the uge gene was lower in RTx patients on everolimus when compared to isolates from patients not receiving mTOR inhibitors (33.3 % vs 82.8 % P<0.05). K. pneumoniae upper UTI may be a marker of urine flow impairment. Bacterial VFs could not discriminate between upper and lower UTIs. However, immunosuppression may influence the selection of particular VFs.

Investigation of phase change materials integrated with fin-tube baseboard convector for space heating

The objective of this study was to investigate the design of a fin tube baseboard convector space heating (FBC-SH) system filled with phase change material (PCM) and analyze its performance during the melting (i.e., charging) and solidification (i.e., discharging) processes of the PCM. The effect of the orientation of the FBC-SH system on the phase change processes was also investigated to determine the thermally efficient orientation during the FBC-SH system's operation. An experimental set up was developed and detailed experimental investigations were carried out on a prototype FBC-SH system. The FBC-SH system was charged and discharged using deionized water as a heat transfer fluid (HTF) at 70 °C and 20 °C, respectively. Ten thermocouples were fixed in specified locations, and temperature readings were collected at 10 s intervals and processed. Images of melting and solidification processes were captured. Three orientations were examined: (i) vertical orientation (90°), (ii) horizontal orientation (0°), and (iii) angled orientation (45°). The graphical results of temperature variations displayed changes in temperature during the melting and solidification processes. The major observations of this study illustrated that the solidification process occurs faster than the melting process for all orientations, suggesting that the thermal energy was released at a faster rate than it can be absorbed. Due to changes in orientation of the FBC-SH chamber, height of the PCM associated with natural convection changes, the melting process occurred faster in the horizontal orientation when compared to the melting processes for the vertical and angled orientations. The horizontal orientation displayed a more even thermal energy distribution along the FBC-SH chamber compared to the angled and vertical orientations. This was observed by the melting profiles presented as images captured during the charging and discharging experiments. The charged thermal energy is higher than the discharged thermal energy. The horizontal orientation stored the greatest amount of thermal energy (295.47 kJ) and released the least amount of thermal energy (166.05 kJ). The vertical orientation stored the least amount of thermal energy (287.86 kJ) and released the greatest amount of energy (265.67 kJ) compared to the horizontal and angled orientations.

The Effect of Submarine Melting on Calving From Marine Terminating Glaciers

Submarine melting and iceberg calving are two important processes that control mass loss from the terminus of tidewater glaciers. There have been significant efforts to quantify the effect of submarine melting on glacier calving, but controversy remains with conflicting studies indicating submarine melting can increase, decrease, or has minimal effect on calving. Here we show using a two‐dimensional full Stokes finite element model that submarine melt can alter the state of stress near the terminus and the changes in stress exert a first‐order control on the calving regime of marine terminating glaciers. The model calculates both the largest principal and maximum shear stresses and then maps out where tensile and shear failure occur for a range of melt rates and vertical melt profiles. We find that submarine melt initially promotes full thickness calving events. However, as the melt rate further increases, an overhang begins to form and resulting compressive stresses suppress full thickness calving. These results are relatively insensitive to basal friction. Moreover, our results suggest that submarine melting can both increase and decrease calving rates with the magnitude and sign of the effect determined by the shape of the melt profile and the relative magnitude of average melt rate. Despite the fact that calving is suppressed in some circumstances, the addition of submarine melt almost always increases the total mass loss. Overall, we find that relatively small amounts of submarine melt can destabilize glaciers, but calving and frontal ablation are increasingly controlled by submarine melt as it continues to increase.