Magnesium Infiltration Research Articles

Research on Microstructure and Corrosion Behavior of Zinc-Magnesium Coating by Powder Impregnation

In order to improve the service life of railway fasteners under various environmental conditions, the Zn and Zn-Mg coating were prepared on the railway fastener gaskets by powder impregnation. XRD and SEM were used to characterize the phase composition, microstructure and morphology before and after the salt spray. The neutral salt spray test (NSST) and the electrochemical workstation were used to characterize the corrosion resistance of the two coatings. Results show that there was a large area of red rust on Zn coating after 480 hours of NSST, while there was no red rust on Zn-Mg coating after 1920 hours of NSST. The impedance of the Zn-Mg coating reached 1015.6 Ω·cm2, about 3.65 times of the Zn coating. Zn-Mg coating’ current density was 3.27 μA·cm−2, which was only 21% of the Zn coating. MgZn2 and Mg2Zn11 phases were easier to formed in Zn-Mg coating due to the infiltration of magnesium, forming a dense and protective layer, thereby greatly improved its corrosion resistance.

Influence of Magnesium Infiltration on Compressive Behavior of Additively Manufactured Porous Ti6Al4V Structure

Abstract As the next generation of metallic implants, Ti6Al4V porous structures have captivated more attention; however, the primitive compressive strength of the Ti6Al4V material is drastically reduced in its porous form while matching its Young’s modulus with that of the bone to avoid ‘stress-shielding effect’. This work sheds light on an unconventional approach to develop a metallic implant that addresses the twin demands of having high compressive strength and low Young’s modulus matching with that of the bone. This study focuses exclusively on the compressive behavior because most of the implants like hip and knee prosthesis are subjected to compressive loading. Porous Ti6Al4V structures with porosity ranging from 60–75 % are fabricated using electron beam melting, an additive manufacturing technique. And then, a pressureless infiltration technique is carried out to infiltrate pure magnesium, a good biodegradable material, into the porous structures by casting process. The compressive behavior of the infiltrated structures is analyzed and compared with porous Ti6Al4V structures. The compressive strength of the porous Ti6Al4V structures is enhanced up to 200 % after infiltrating it with biodegradable magnesium without much change in the modulus, making it a good candidate for the biomedical metallic implants. Moreover, the stress-strain characteristics of the magnesium-infiltrated Ti6Al4V samples exhibited ductile nature when compared with the stress-strain curves of the porous Ti6Al4V samples, which showed brittle nature, thereby enhancing the energy-absorbing quality of the metallic implant.

Diffusion‐Triggered Synthesis of Mg2Si Based on Infiltrated Silicon Structures in Molten Mg

Magnesium silicide (Mg2Si) has many good properties and therefore shows a high application potential as thermoelectric material. Herein, the intermetallic layer growth behavior in the Mg–Si system is investigated. A process for synthesizing Mg2Si on the surface of open‐pore cellular Si structures is developed. The structure is fabricated by investment casting and followed by infiltration of magnesium. Subsequently, magnesium silicide is obtained by a two‐step heat treatment. Complete synthesis of Si to Mg2Si is achieved using a liquid–solid reaction between the liquid Mg and solid Si. The optimal heat treatment for the first step is at the eutectic temperature of 950 °C and for a duration of 120 min. The second treatment is at 1150 °C, slightly above the melting point of Mg2Si, and the remaining Si is synthesized. The resulting microstructures are analyzed using a scanning electron microscope (SEM) and energy‐dispersive spectroscopy (EDS).

An MgB$_2$ Superconducting Shield Prototype for the Future Circular Collider Septum Magnet

A passive superconducting shield was previously proposed to realize a high-field (above 3 T) septum magnet for the Future Circular Collider proton–proton ring (FCC-hh). This paper presents the experimental results of a potential shield material, MgB $_2$ , at a temperature of 4.2 K. A cylindrical shield with a wall thickness of 8.3 mm was manufactured by the reactive liquid magnesium infiltration technique using extra large grain ( $\sim$ 160 $\mu$ m) boron precursor, and tested in a transverse magnetic field. The shield was stable against flux jumps on the virgin curve, but suffered from flux jumps at low-field levels after high-field exposure. The tube could shield a magnetic field of 2.75 T on its surface before field penetration to its interior. Parameters of the critical current density of the material could be estimated from simulations, which indicate a steeper $J_c(B)$ curve than observed previously for large grain ( $\sim$ 100 $\mu$ m) MgB $_2$ , and predict a slightly better shielding performance (3 T) with an ideal geometry. Relaxation of the shielding currents is at an acceptable level. We estimate that a self-supporting shield of a wall thickness of 14 mm could be adequate for the construction of a 3-T septum magnet, if the flux jump problem can be solved. This thickness would correspond to a total septum thickness (including beam pipes, etc.) of around 22 mm, which is an acceptable figure for the FCC-hh.

Pain alleviation in patients undergoing cardiac surgery; presternal local anesthetic and magnesium infiltration versus conventional intravenous analgesia: a randomized double-blind study.

BackgroundMagnesium is one of the effective, safe local anesthetic adjuvants that can exert an analgesic effect in conditions presenting acute and chronic post-sternotomy pain. We studied the efficacy of continuous infusion of presternal magnesium sulfate with bupivacaine for pain relief following cardiac surgery.MethodsNinety adult patients undergoing valve replacement cardiac surgery randomly allocated into three groups. In all patients; a presternal catheter was placed for continuous infusion of either 0.125% bupivacaine and 5% magnesium sulfate (3 ml/h for 48 hours) in group 1, or 0.125% bupivacaine only in the same rate in group 2, versus conventional intravenous paracetamol and ketorolac in group 3. Rescue analgesia was iv 25 µg fentanyl. Postoperative Visual Analog Scale (VAS) and fentanyl consumption during the early two postoperative days were assessed. All patients were followed up over two months for occurrence of chronic post-sternotomy pain.ResultsVAS values showed high significant differences during the first 48 hours with the least pain scale in group 1 and significantly least fentanyl consumption (30.8 ± 7 µg in group 1 vs. 69 ± 18 µg in group 2, and 162 ± 3 in group 3 respectively). The incidence of chronic pain has not differed between the three groups although it was more pronounced in group 3.ConclusionsContinuous presternal bupivacaine and magnesium infusion resulted in better postoperative analgesia than both presternal bupivacaine alone or conventional analgesic groups.

Adjuncts to local anaesthetics in tonsillectomy: a systematic review and meta-analysis.

The infiltration of local anaesthetic agents has been shown to reduce post-tonsillectomy pain. A number of recent studies have shown that the addition of agents such as clonidine and dexamethasone improve the efficacy of nerve blocks and spinal anaesthesia. The aim of this review was to determine whether additives to local anaesthetic agents improve post-tonsillectomy outcomes. Four major databases were systematically searched for all relevant studies published up to August 2016. All study designs with a control group receiving local anaesthetic infiltration and an intervention receiving the same infiltration with an added agent were included in this review. These studies were then assessed for level of evidence and risk of bias. The data were then analysed both qualitatively and where appropriate by meta-analysis. We reviewed 11 randomised controlled trial (RCTs) that included 854 patients. Due to inconsistencies in the methods used to report outcomes, both quantitative and qualitative comparisons were required to analyse the extracted data. Overall, we found that dexamethasone, magnesium, pethidine and tramadol reduce post-operative pain and analgesia use, with dexamethasone in particular significantly reducing post-operative nausea and vomiting and magnesium infiltration significantly reducing the incidence of laryngospasm. This systematic review of RCTs provides strong evidence that the use of dexamethasone and magnesium as additives to local anaesthetics reduces post-tonsillectomy pain and analgesia requirement. There is limited evidence that pethidine and tramadol have a similar effect on pain and analgesia requirement. The studies in this pooled analysis are sufficiently strong to make a level one recommendation that the addition of magnesium to local anaesthetics reduces the incidence of laryngospasm, a potentially lethal post-operative complication. Review level of evidence: 1.

Efficacy of Magnesium Sulphate as an Adjunct to Ropivacaine in Local Infiltration for Postoperative Pain Following Lower Segment Caesarean Section.

Intravenous and peri-articular magnesium has been shown to reduce perioperative analgesic consumption. With this background, subcutaneous infiltration was hypothesized to potentiate the subcutaneous infiltration of local anaesthetic agent. To comparatively evaluate the efficacy of magnesium sulphate as an adjunct to ropivacaine in local infiltration for postoperative pain following lower segment cesarean section. Sixty parturients undergoing cesarean delivery were randomized to either group A or B in a double blinded manner. After uterine and muscle closure but before skin closure, Group A was administered local subcutaneous wound infiltration of Injection (Inj) ropivacaine 0.75% 150 milligram (mg) or 20 millilitres(ml) whereas, group B patients were given a local subcutaneous wound infiltration of Inj magnesium sulphate 750 mg (1.5 ml of Inj 50% Magnesium sulphate) added to Inj ropivacaine 0.75% (18.5 ml) making a total volume of 20 ml. In postoperative period, Heart rate (HR), Mean Arterial Pressure (MAP), Visual Analogue Score (VAS), supplemental analgesic consumption and timing of each subsequent analgesic was noted for the initial 24 hours. There was no difference in the timings for the requirement of first Intravenous (IV) rescue analgesic among both the groups (p=0.279). However, the need for 2(nd) and 3(rd) doses of rescue analgesics was significantly later in group B and the difference was statistically significant with p-value of 0.034 and 0.031 respectively. The number of patients who were administered 2(nd), 3(rd) and 4(th) doses of rescue analgesics was significantly greater in group A as compared to group B. None of the patients in group B needed more than 4 doses of rescue analgesia while in group A, 5 patients were administered a rescue analgesic for 5(th) time. The cumulative analgesic requirement in the initial 24 hours was also greater in group A as compared to group B and the difference was statistically significant (p =0.01). The incidence of adverse effects was similar in both the groups. Subcutaneous infiltration of magnesium along with local anaesthetic prolongs the analgesic efficacy of local anaesthetic and is not associated with any significant adverse effects.

Magnesium Versus Bupivacaine Infiltration in Controlling Postoperative Pain in Inguinal Hernia Repair.

Background:Postoperative pain is one of the most common problems after hernia repair. Decrease in postoperative pain accelerates functional recovery, decreases duration of hospital stay and postoperative morbidity.Objectives:To compare postoperative analgesic effect of infiltration of magnesium versus bupivacaine into incision of inguinal hernia repair.Patients and Methods:In a double blind clinical trial, 80 patients’ candidates for elective inguinal hernia repair were enrolled. Right before closure of incision, in Bupivacaine group 5 mL Bupivacaine 0.5% added to 5 mL normal saline and in Magnesium group, 10 mL Magnesium sulfate 20% was infused subcutaneously. Pain score was measured using numeric rating score (NRS) at 1, 3, 6, 12 and 24 hours postoperatively. If NRS was above 3, 1 mg morphine was administered as rescue analgesic until patient felt comfortable or NRS < 3.Results:Postoperative pain scores at 1 and 3 hours were not significantly different between bupivacaine and magnesium groups (P = 0.21, 0.224; respectively). However, at 6 (P = 0.003), 12 (P = 0.028) and 24 (P = 0.022) hours postoperative, pain score (NRS) was significantly lower in bupivacaine group. Number of patients needed at least 1 dose of rescue morphine (P = 0.001), mean number of episodes asked for morphine during next 24 hours (P = 0.001) and total dose of morphine requirement (P = 0.01) were significantly lower in bupivacaine group.Conclusions:Magnesium infiltration did not decrease total dose and number of episodes needed for morphine rescue analgesic. Bupivacaine infiltration into surgical site was more effective than magnesium sulfate infiltration in postoperative pain control.

Influence of twisting and bending on the Jc and n-value of multifilamentary MgB2 strands

The influences of strand twisting and bending (applied at room temperature) on the critical current densities, Jc, and n-values of MgB2 multifilamentary strands were evaluated at 4.2 K as function of applied field strength, B. Three types of MgB2 strand were evaluated: (i) advanced internal magnesium infiltration (AIMI)-processed strands with 18 filaments (AIMI-18), (ii) powder-in-tube (PIT) strands processed using a continuous tube forming and filling (CTFF) technique with 36 filaments (PIT-36) and (iii) CTFF processed PIT strands with 54 filaments (PIT-54). Transport measurements of Jc(B) and n-value at 4.2 K in fields of up to 10 T were made on: (i) PIT-54 after it was twisted (at room temperature) to twist pitch values, Lp, of 10–100 mm. Transport measurements of Jc(B) and n-value were performed at 4.2 K; (ii) PIT-36 and AIMI-18 after applying bending strains up to 0.6% at room temperature.PIT-54 twisted to pitches of 100 mm down to 10 mm exhibited no degradation in Jc(B) and only small changes in n-value. Both the Jc(B) and n-value of PIT-36 were seen to be tolerant to bending strain of up to 0.4%. On the other hand, AIMI-18 showed ±10% changes in Jc(B) and significant scatter in n-value over the bending strain range of 0-0.6%.

Pre-emptive peritonsillar infiltration of magnesium sulphate and ropivacaine vs. ropivacaine or magnesium alone for relief of post-adenotonsillectomy pain in children

ObjectivesThe randomized, double-blinded, placebo-controlled study evaluated the administration of local infiltration of magnesium combined with ropivacaine to reduce pain scores after pediatric adenotonsillectomy. MethodsSixty one subjects received 5ml solution contained 0.25% ropivacaine plus 5mg/kg magnesium sulphate (Group M+R), 5ml 0.25% ropivacaine (Group R) or 5ml solution contained 5mg/kg magnesium sulphate (Group M). Pain scores in the ward and at home, analgesics received after operation and the adverse effects were recorded. ResultsCompared with group M, patients in group M+R and group R had lower pain scores, less emergence agitation and increased time for first analgesic request. Group M+R had no benefit in reducing pain scores after adenotonsillectomy compared with group R. ConclusionsPre-emptive peritonsillar infiltration of magnesium sulphate 5mg/kg combined with 0.25% ropivacaine couldn’t improve analgesia for pediatric adenotonsillectomy compared with 0.25% ropivacaine alone. However, Group M+R had less incidence of emergence agitation. Compared with group M, both of group M+R and group R had better postoperative analgesia.

Carbon doping of precursor boron powder for control of normal resistance of MgB2 bulks for specific use in fault current limiter applications

Magnesium Diboride (MgB2) bulk superconductor has been manufactured in order to study the enhancement of the normal resistivity for application to superconducting fault current limiters (SFCLs). SFCLs have proven to be a viable means for limiting surge currents by dissipating fault energy as the superconductor quenches. As the current limiting behaviour is determined by the normal resistivity (ρn), research has been conducted to evaluate an effective means to increase ρn for bulk superconducting MgB2, which is intrinsically much lower than for high temperature superconductors. Intragranular carbon doping has been confirmed as a means to increase ρn, and was implemented by chemical vapour deposition (CVD) on the boron precursor powder by ethylene gas at 600 °C for durations up to 6 hours in a tubular furnace apparatus. In situ manufacturing of MgB2 bulk was performed using the reactive liquid magnesium infiltration technique. Overall, carbon doping provided a factor of 11.00 increase in the residual resistivity, ρ0, which provides the initial limiting action to fault currents, for an accompanying decrease in the critical temperature, Tc, of 2 K.

Plastic Micromechanical Response of 2D Cross Ply Magnesium Matrix Composites

2D cross ply magnesium matrix composites were fabricated by melt magnesium infiltration in carbon fiber preform. Carbon fiber uni-directional fabric was used to prepare the carbon fiber preform by alternatively placing fabric in orthogonal way layer by layer. Preform was strengthened by stitching in the perpendicular direction to the fabric layers. The micromechanical model was generated based on the real microstructue of 2D cross ply magnesium matrix composites. The plastic response of 2D cross ply magnesium matrix composites was predicted based on the constructed micromechanical model by applying tensile load in different direction with respect to the fabric direction. Effects of layer mode and packing mode on the plastic response were investigated by numerical simulation. The results showed that composites were strengthened maximally along the fabric direction. Layering mode of fabric played important role on the plastic response of composite. The best layer mode for maximum properties improvement was that perpendicular layer and parallel layer should be used alternatively. The simulated results were verified through corresponding experiments.

Use of $\hbox{MgB}_{2}$ Superconductors for Excitation Field in Synchronous Machines—Part I: Bulk Magnets

Magnesium diboride is a promising superconducting material with interesting electrical and mechanical properties. Reactive liquid magnesium infiltration is an effective technology to produce cheap and reliable bulk components potentially suitable for application in electric machinery. This study deals with the magnetic flux-trapping capabilities of bulk samples manufactured through this technique. The aim of this work is to evaluate the samples as magnets for synchronous machines. In this paper, a number of trapped flux measurements on different magnesium diboride samples are reported. The experimental results are discussed on the basis of the numerical model of the superconducting material.

チタン粉末の積層造形とマグネシウムの自発的溶浸による複合材料部品作製技術の開発

A manufacturing technique for the modeling of titanium powder by indirect selective laser sintering (SLS) and magnesium infiltration was developed. The modeling powder used for the indirect SLS was prepared by coating 1.1 mass% nylon with titanium powder particles and then mixing 1.9 mass% phenol resin powder (<10 µm). The hardness of the modeling powder at 477 K was greater than that of A90 (durometer type A), and it was suitable for indirect SLS modeling. While the amounts of resin (nylon and phenol) were equal in both methods, unlike the use of nylon coating and phenol resin powder, which resulted in the formation of a sufficiently hard titanium powder, the use of nylon resin powder and phenol resin powder resulted in the formation of an insufficiently hard titanium powder. The titanium powder preform and a magnesium ingot were then heated at 973 K, and the dense composite, consisting of titanium particles and infiltrated magnesium, was fabricated by the self-activation of the infiltrated molten magnesium. Microstructure analyses of the composites titanium, magnesium, and titanium-carbide (TiC) were conducted by XRD. We concluded that the formation of TiC was attributed to the formation of titanium and carbon during the decomposition of the phenol resin. The density, hardness, and tensile strength of the obtained composites are 3.2, 60 HRB, and 241 MPa, respectively. The tensile strengths of the composites are significantly higher than those of the cast magnesium (106 MPa). We believe that a large increase in the tensile strength after infiltration was due to the sintered behavior of the titanium powder and the densification of magnesium infiltration. Thus, the infiltration of magnesium into the titanium powder preform can be considered as an effective method for manufacturing lightweight composites.

間接的なレーザ選択焼結によるステンレス鋼多孔質体への軽金属の自発的溶浸

In this study, we attempted to infiltrate molten aluminum, magnesium, and magnesium-zinc alloy into stainless steel preforms fabricated by indirect selective laser sintering (SLS). In the case of aluminum, infiltration did not occur; it was inhibited by the intermetallic compound (Al3Fe) formed by the active reaction between molten aluminum and stainless steel powder. Molten magnesium and magnesium-zinc alloy, however, smoothly infiltrated into the stainless steel preforms, and the infiltrated parts were found to maintain excellent dimensional accuracy. The hardness and tensile strength of the infiltrated parts of magnesium are 65 HRB and 265 MPa, respectively, and the corresponding values for magnesium-zinc alloy are 72 HRB and 305 MPa, respectively. The tensile strengths of the infiltrated parts are significantly higher than those of the casting materials (106 MPa for magnesium and 270 MPa for magnesium-zinc alloy). We believe that the large increase in tensile strength after infiltration was due to the composite reinforcement of the matrix and stainless steel particles. Thus, the infiltration of magnesium and magnesium-zinc alloy into stainless steel powder preform can be considered as an effective indirect SLS technique for producing lightweight infiltrated metal-alloy parts.

Previsão de bitter pit em maçãs por meio da infiltração de Mg2+ e da aplicação de ethephon nos frutos

Estudou-se o efeito da infiltração de magnésio e cálcio no desenvolvimento de sintomas de bitter pit de maçãs 'Gala'. Examinou-se, também, a eficiência da infiltração de magnésio e da aceleração da maturação de maçãs 'Royal Gala' como métodos de previsão da ocorrência de bitter pit após o armazenamento. No primeiro experimento, maçãs 'Gala' foram infiltradas com MgCl2; CaCl2 ou MgCl2 mais CaCl2. No segundo experimento, maçãs 'Royal Gala' foram infiltradas com MgCl2; ou imersas em solução contendo ethephon por cinco minutos. Como controle, frutos de cada cultivar foram armazenados em atmosfera controlada por seis meses mais 18 dias a 20°C. Frutos infiltrados com MgCl2 apresentaram significativo acréscimo na incidência e severidade de bitter pit, proporcional à concentração de MgCl2 na solução. Frutos infiltrados com CaCl2 não apresentaram sintomas de bitter pit. A aceleração da maturação de maçãs 'Royal Gala' na colheita foi efetiva na previsão de bitter pit após o armazenamento.

INFILTRATION OF MAGNESIUM IN POROUS BORON SKELETONS

The feasibility of the infiltration of molten magnesium into porous boron skeleton was examined. The particle size and crystalline state of starting boron powders as well as the confinement of Mg vapors play an important role in successful infiltration. Magnesium penetrates more readily into porous skeletons formed by large crystalline boron particles than those formed by fine amorphous powders. The infiltration of magnesium mainly occurs via capillary condensation rather than liquid flow. Although the infiltrated microstructures are seemingly very dense, nano-scale structures contain many tiny inter-particle voids due to random packing of MgB 2 grains. This is due to the absence of a liquid phase in final microstructures as a result of transient liquid-phase infiltration.

Métodos para predição de bitter pit em maçãs 'Fuji' e 'Braeburn'

Experimentos foram conduzidos com objetivo de avaliar a eficiência de métodos para predição da ocorrência de bitter pit em maçãs 'Fuji' e 'Braeburn' em duas épocas de amostragem. Os frutos, provenientes de seis pomares distintos, três para cada cultivar, foram coletados antecipadamente (20 dias em relação à colheita) e na data prevista para a colheita comercial. Os métodos de predição utilizados foram: a) infiltração dos frutos com solução 0,10M MgCl2 mais 0,01% Tween-20 e 0,4M de sorbitol; b) imersão dos frutos em solução com 2500nL L-1 de ethephon mais 0,01% Tween-20. Os frutos foram armazenados em atmosfera controlada (AC) por cinco meses mais 12 dias, a 20°C, simulando a incidência real de bitter pit em armazenamento comercial. Cada tratamento foi constituído por quatro repetições de 25 frutos. A incidência e severidade de bitter pit, prevista por ambos os métodos foi semelhante à ocorrência real de bitter pit após o armazenamento em atmosfera controlada para cada uma das cultivares utilizadas, quando os frutos foram amostrados antecipadamente em relação à colheita comercial. Na avaliação realizada com frutos amostrados na colheita comercial, nenhum dos métodos foi capaz de prever a incidência de bitter pit após o armazenamento de maneira confiável. Para ambas as cultivares, a infiltração com magnésio e a imersão dos frutos em ethephon só são eficientes na predição da incidência de bitter pit em frutos coletados 20 dias antes da colheita comercial.

The effects of levobupivacaine versus levobupivacaine plus magnesium infiltration on postoperative analgesia and laryngospasm in pediatric tonsillectomy patients

The aim of this study was to evaluate whether the addition of magnesium to levobupivacaine will decrease the postoperative analgesic requirement or not, and to investigate the possible preventive effects on laryngospasm. Seventy-five children undergoing elective tonsillectomy and/or adenoidectomy surgery. The drug was prepared as only NaCl 0.9% for the first group (Group S, n=25), levobupivacaine 0.25% for the second group (Group L, n=25), and levobupivacaine 0.25% plus magnesium sulphate 2mg/kg for the third group (Group M, n=25). Pain was recorded at 15th minute, 1st, 4th, 8th, 16th, and 24th hour postoperatively. Pain was evaluated using a modified Children's Hospital of Eastern Ontario pain scale (mCHEOPS). Incidence of postoperative nausea and vomiting (PONV) was assessed at various time intervals (0-2, 2-6, 6-24h) by numeric rank score. Patients were followed for laryngospasm for 1h in recovery room after extubation. Other complications appeared within 24h postoperatively were recorded. All postoperative CHEOPS values were lower than control in both groups. Analgesic requirement was decreased significantly in both groups in comparison with control patients, but this requirement was significantly lower in Group M (p<0.05). Although laryngospasm was not observed in Group M, the difference between groups was not statistically significant. PONV was similar in both groups. Levobupivacaine and Levobupivacaine plus magnesium infiltration decrease the post-tonsillectomy analgesic requirement. Insignificant preventive effect of low doses of magnesium infiltration on laryngospasm observed in this study needs to be clarified by larger series.

Polypeptide Pattern of Apple Tissues Affected by Calcium-related Physiopathologies

Polypeptides from the apple pulp of Smoothee Golden Delicious and White Renete apples were resolved by 1-D denaturing sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). According to the electropherograms, there were lower concentrations of 88, 74, 70.6 and 47.5-42kDa proteins in bitter pit spots. Proteins weighing 30 and 26kDa were rare in sound pulp but frequently appeared in pits and adjacent tissue. Finally, a novel 18kDa protein was found in bitter pit spots in both varieties, and also in chemically induced corky lesions either by magnesium infiltration or ammonium oxalate cortical injections. The available data suggested that the novel protein might be an inhibitor of pectinmethylesterase, a small heat stress protein (smHSP) or a product of the Ypr-10 gene family identified with ‘Mal d 1’, the main allergen of apples. To elucidate the possible smHSP nature of the 18kDa, a set of apples were heated at 40°C for 20h, developing this protein in both the oxidised tissue and in the adjacent.