Premature Degradation Research Articles

Understanding of failure mechanisms of the oxide scales formed on nanocrystalline coatings with different Al content during cyclic oxidation

Cyclic oxidation behaviors of three nanocrystalline coatings with phase constitutions of γ/γʹ, single γʹ, and γʹ/β, respectively, tailored by adjusting the Al content, are investigated. The oxide scale on γ/γʹ coating exhibits serious surface rumpling accompanied by frequently cracking at the crests of undulations after 500 cycles at 1100°C. The premature degradation of the coating in microstructure (i.e. γ′ phase dissolution and concurrent grain coarsening), arising from high oxidation rate and low original Al content, not only increases its CTE to introduce larger thermal stress, but also decreases its hardness and elastic modulus, making it susceptible to rumpling and further inducing cracking of oxide scale. Comparatively, benefited from lower oxidation rate and higher Al content, the degradation of γʹ and γʹ/β coatings is less significant. They are subjected to lower thermal stress but possess higher deformation resistance during cycling. However, local spallation of the oxide scale occurs on γʹ/β coating since it is insusceptible to rumpling and thus the thermal stress is difficult to release in time by plastic deformation. The γʹ coating outperforms its counterparts of γ/γʹ and γʹ/β coatings, presenting low oxidation rate, high resistance to scale cracking and spallation, meanwhile, limited elements-interdiffusion with the underlying substrate.

Understanding the role of colon-specific microparticles based on retrograded starch/pectin in the delivery of chitosan nanoparticles along the gastrointestinal tract

The encapsulation of nanoparticles within microparticles designed for specific delivery to the colon is a relevant strategy to avoid premature degradation or release of nanoparticles during their passage through the stomach and upper gastrointestinal tract (GIT), allowing the targeted delivery of chemotherapeutics to the colon after oral administration. Here, we designed an oral multiparticulate system to achieve targeted release in the colon. In this sense, chitosan nanoparticles (CS NPs) encapsulated with 5-fluorouracil (5-FU) and incorporated into retrograded starch and pectin (RS/P) microparticles were developed and their in vivo distribution along the mouse GIT after oral administration was monitored using multispectral optical imaging. In vitro release studies revealed that the encapsulation of CS NPs into RS/P microparticles promoted greater control of 5-FU release rates, with a significant reduction (53%) in acid media that might replicate that found in the stomach following oral administration. The evaluation of the in vivo biodistribution of the CS NPs in mice showed a faster clearance in the distribution pattern along the mouse GIT, i.e., a shorter transit time of CS NPs compared to CS NPs-loaded RS/P microparticles. Additionally, CS NPs alone showed non-specific absorption into the blood-stream with associated kidney accumulation, while for the CS NPs-loaded RS/P microparticles no significant accumulation was observed in blood or major clearance organs. This suggests the specific degradability of RS/P by the colon microbiota appears to have been decisive in the higher protection of the CS NPs along the GIT until release in the colon, preventing unwanted absorption into the bloodstream and major organs following oral administration. Our findings represent a proof of concept for the use of RS/P microparticles as potential carriers for delivering drug-loaded nanoparticles to the colon and this work will contribute to the development of oral-systems for colorectal cancer therapy.

Carbide-laden coatings deposited using a hand-held high-velocity air-fuel (HVAF) spray gun

Driven by sustainability and cost considerations, there is growing interest in power generation utilizing renewable sources, especially biomass and waste. While premature degradation of power plant components due to corrosion is well-known, erosion can be a dominant damage mechanism in plants that use “pure” biomass with less corrosive elements like Cl, K, etc. Circulating fluidized bed (CFB) parts are prone to erosion-driven damage and demand periodic re-protection or replacement. In response to the above, this preliminary study evaluates a selection of complex carbide-based coatings to enhance protection against erosion to prolong service life of boiler components. Recognizing on-site coating requirements of real boiler applications, a specific focus is on evaluating performance of a hand-held high-velocity air-fuel (HVAF) spray gun and compare it with the current state-of-the-art high-velocity oxy-fuel (HVOF) deposition. Coatings developed by the above routes have been characterized with microstructural analyses, and their performance evaluated and ranked in an air-jet erosion rig at various impact angles.

On-axis fatigue behaviors and failure characterization of 3D5D braided composites with yarn-reduction using X-ray computed tomography

This paper mainly provides a thorough experimental investigation of tension-tension fatigue (R = 0.1) failure mechanisms in 3D5D braided carbon/epoxy composites without/with yarn-reduction (No-YR/In-YR) subjected to different stress levels of ultimate tensile stress (40%-75%UTS). X-ray computed tomography (Micro-CT) was conducted to visualize and quantify the damage generated in the fatigued samples. More significantly, a novel two-steps segmentation approach was proposed to classify and locate the cracks. The results indicated that the two types of specimens showed similar fatigue behavior, i.e. the extensive debonding of the braided yarns might give rise to the premature significant stiffness degradation of the fatigued samples. However, the tensile strength and the fatigue limit of In-YR 3D5D braided composites were reduced by 28.3% and 22.8% relative to No-YR 3D5D braided composites, respectively, which might be attributed to the variation of failure modes. Particularly, the failure modes of the axial yarns surround the yarn-reduction point evolved from mode I to mode II due to the deformation generated during the fabrication. It is noteworthy that the cracks presented a typical wedge distribution near the yarn reduction point due to the in-plane stress migration.

Causes and consequences of RNA polymerase II stalling during transcript elongation.

The journey of RNA polymerase II (Pol II) as it transcribes a gene is anything but a smooth ride. Transcript elongation is discontinuous and can be perturbed by intrinsic regulatory barriers, such as promoter-proximal pausing, nucleosomes, RNA secondary structures and the underlying DNA sequence. More substantial blocking of Pol II translocation can be caused by other physiological circumstances and extrinsic obstacles, including other transcribing polymerases, the replication machinery and several types of DNA damage, such as bulky lesions and DNA double-strand breaks. Although numerous different obstacles cause Pol II stalling or arrest, the cell somehow distinguishes between them and invokes different mechanisms to resolve each roadblock. Resolution of Pol II blocking can be as straightforward as temporary backtracking and transcription elongation factor S-II (TFIIS)-dependent RNA cleavage, or as drastic as premature transcription termination or degradation of polyubiquitylated Pol II and its associated nascent RNA. In this Review, we discuss the current knowledge of how these different Pol II stalling contexts are distinguished by the cell, how they overlap with each other, how they are resolved and how, when unresolved, they can cause genome instability.

The effects of ambient storage conditions on the structural and electrochemical properties of NMC-811 cathodes for Li-ion batteries

High-Ni cathode materials are prone to reactivity and instability upon exposure to ambient levels of humidity. This has implications for the storage and processing of cathodes for Li-ion batteries (LIBs), in order to avoid any premature degradation of the material prior to operation. NMC-811 materials were subjected to differing degrees of exposure to ambient humidity, in order to establish the impact this would have on electrochemical performance. This study used a combination of physical, chemical and electrochemical methods to investigate the operational effects that moisture can have on the battery accordingly. Longer-term cycling, d-SIMS and microscopy were used to characterise the degradation phenomena and relating to capacity fade. Post-mortem analysis revealed that the structural breakdown of the secondary particles is a dominant factor that influences charge transfer resistance increases. The study highlights the criticality of how high Ni materials are handled during storage and processing, in order to mitigate premature degradation events during operation.

Degradation kinetics of alkali-activated mortar in aggressive citric acid environment

Acid attack is a complex phenomenon arising in construction industries worldwide as it is responsible for the deterioration of concrete in acidic environments resulting in premature degradation with regard to mass changes, weakening of mechanical properties, and increase in porosity due to calcium leaching. This paper investigates the citric acid resistance of geopolymer composites (GP) and its comparison with conventional concrete system (OPC) in lower and higher concentrations of acid medium. The GP samples displayed increased resistance to citric acid attack than OPC system in terms of mass and strength loss. It was also found that geopolymer mortar made with a blend of ground granulated blast furnace slag (GGBS) and red mud (RM) offered increased acid resistance based on the parameters studied in the degradation kinetics

Endoplasmic Reticulum Associated Protein Degradation (ERAD) in the Pathology of Diseases Related to TGFβ Signaling Pathway: Future Therapeutic Perspectives.

The transforming growth factor signaling pathway (TGFβ) controls a wide range of cellular activities in adulthood as well as during embryogenesis including cell growth, differentiation, apoptosis, immunological responses and other cellular functions. Therefore, germline mutations in components of the pathway have given rise to a heterogeneous spectrum of hereditary diseases with variable phenotypes associated with malformations in the cardiovascular, muscular and skeletal systems. Our extensive literature and database searches revealed 47 monogenic diseases associated with germline mutations in 24 out of 41 gene variant encoding for TGFβ components. Most of the TGFβ components are membrane or secretory proteins and they are therefore expected to pass through the endoplasmic reticulum (ER), where fidelity of proteins folding is stringently monitored via the ER quality control machineries. Elucidation of the molecular mechanisms of mutant proteins’ folding and trafficking showed the implication of ER associated protein degradation (ERAD) in the pathogenesis of some of the diseases. For example, hereditary hemorrhagic telangiectasia types 1 and 2 (HHT1 and HHT2) and familial pulmonary arterial hypertension (FPAH) associated with mutations in Endoglin, ALK1 and BMPR2 components of the signaling pathway, respectively, have all exhibited loss of function phenotype as a result of ER retention of some of their disease-causing variants. In some cases, this has led to premature protein degradation through the proteasomal pathway. We anticipate that ERAD will be involved in the mechanisms of other TGFβ signaling components and therefore warrants further research. In this review, we highlight advances in ER quality control mechanisms and their modulation as a potential therapeutic target in general with particular focus on prospect of their implementation in the treatment of monogenic diseases associated with TGFβ components including HHT1, HHT2, and PAH. In particular, we emphasis the need to establish disease mechanisms and to implement such novel approaches in modulating the molecular pathway of mutant TGFβ components in the quest for restoring protein folding and trafficking as a therapeutic approach.

Cyclic response and modelling of special moment resisting beams exhibiting fixed-end rotation

Rebar slippage in reinforced concrete (RC) elements results in concrete expansion, large cracks, and consequently, early deterioration of strength as well as premature stiffness degradation, particularly in the inelastic energy dissipating zones. Although design standards prescribe different minimum concrete compressive strength, seismic evaluation and retrofit standards, and guidelines permit the use of provisions regarding bond strength and bar slippage issues regardless of the minimum specified concrete strength postulated in design standards. To better understand the seismic behavior of special moment-resisting (SMR) beams exhibiting fixed-end rotation resulting from the rebars inelastic elongation and slip, quasi-static cyclic tests were performed on eight full-scale SMR beams. The chosen beams have longitudinal reinforcement ratios of 0.84% (Type-1) and 1.26% (Type-2) with a shear-span to depth ratio of 6.14 and detailed following the provisions of ACI-318-19. Two specimens were prepared for each reinforcement ratio using concrete with compressive strengths equal to 2000 psi (14 MPa, M14) and 3000 psi (21 MPa, M21). The specimens were tested under cyclic displacement protocols, exhibiting flexure yielding that was followed by diagonal shear cracking and, ultimately, bond failure at the beam–block interface. It is even though the beams fulfill the requirements of ACI 318-19 for steel bars embedment and end hooks for anchorage. Force–displacement hysteretic response curves were obtained revealing pinching behavior in the cyclic response. Both types of beams deformed up to maximum chord rotations of 5.22% and 5.73% in case of beams with M14 and M21 concrete, respectively, and experienced cover concrete crushing at the compressed toe. Representative numerical models were assembled implementing fiber-section force-based inelastic beam elements. Additionally, lumped inelastic rotational springs were added to the model for fixed-end rotation. A tri-linear moment-rotation hysteretic response curve has pinching behavior was used to simulate the reduction in re-loading stiffness. This was verified with the measured response of tested beams; excellently simulates the hysteretic response. Moreover, to examine the seismic response of a total structural system regarding these findings, several response history analyses were performed on capacity-designed five-story frames to demonstrate the importance of modeling beam element fixed-end rotation for predicting the story drift demands subjected to different earthquake ground motions. It was found that despite the bar-slip phenomenon the beams developed their yield capacities; however, the response of the frame was subjective depending on the characteristics of input motions, particularly the valleys and hills of the spectral shape.

KIAA0101 and UbcH10 interact to regulate non-small cell lung cancer cell proliferation by disrupting the function of the spindle assembly checkpoint

BackgroundChromosome mis-segregation caused by spindle assembly checkpoint (SAC) dysfunction during mitosis is an important pathogenic factor in cancer, and modulating SAC function has emerged as a potential novel therapy for non-small cell lung cancer (NSCLC). UbcH10 is considered to be associated with SAC function and the pathological types and clinical grades of NSCLC. KIAA0101, which contains a highly conserved proliferating cell nuclear antigen (PCNA)-binding motif that is involved in DNA repair in cancer cells, plays an important role in the regulation of SAC function in NSCLC cells, and bioinformatics predictions showed that this regulatory role is related to UbcH10. We hypothesized KIAA0101 and UbcH10 interact to mediate SAC dysfunction and neoplastic transformation during the development of USCLC.MethodsNSCLC cell lines were used to investigate the spatial-temporal correlation between UbcH10 and KIAA0101 expression and the downstream effects of modulating their expression were evaluated. Further immunoprecipitation assays were used to investigate the possible mechanism underlying the correlation between UbcH10 and KIAA0101. Eventually, the effect of modulating UbcH10 and KIAA010 on tumor growth and its possible mechanisms were explored through in vivo tumor-bearing models.ResultsIn this study, we demonstrated that both UbcH10 and KIAA0101 were upregulated in NSCLC tissues and cells and that their expression levels were correlated in a spatial and temporal manner. Importantly, UbcH10 and KIAA0101 coordinated to mediate the premature degradation of various SAC components to cause further SAC dysfunction and neoplastic proliferation. Moreover, tumor growth in vivo was significantly inhibited by silencing UbcH10 and KIAA0101 expression.ConclusionsKIAA0101 and UbcH10 interact to cause SAC dysfunction, chromosomal instability and malignant proliferation in NSCLC, suggesting that UbcH10 and KIAA0101 are potential therapeutic targets for the treatment of NSCLC by ameliorating SAC function.

Consequences of aircraft operating conditions at military airbases: degradation of ordinary mortar and resistance mechanism of acrylic and silica fume modified cement mortar

Concrete pavements at military airbases are often subjected to extreme aircraft operating conditions such as exposure to high thermal shocks and hydrocarbon fluids, which cause premature degradation and loss of strength. As part of this research project, we replicated aircraft operating circumstances, and investigated their consequences on plain cement mortar as well as on a special type of cement mortar that was prepared using cement, acrylic emulsion (AE) and silica fume (SF). All mortar specimens were repetitively exposed to aircraft operating conditions, which involved the application of aviation oils and high temperature for a short period, both separately and simultaneously. Although AE and SF modified fresh mortar showed saponification during the initial stage of hydration and had a detrimental effect on the compressive strength; the modified cement mortar showed significantly better resistance to the considered harsh conditions as determined by the residual compressive strength. Moreover, the crystalline minerals in AE and SF modified cement mortar were less attacked, decomposed, and found more durable compared to the plain mortar under the extreme conditions. Thus, the study elucidates the degrading mechanisms of plain cement mortar and the added resisting mechanisms of better performing AE and SF modified cement mortar under a replicated military airbase circumstances. This study also suggests limiting the dosage of AE into cement mortar to limit the observed negative impact on compressive strength.

Integrase-RNA interactions underscore the critical role of integrase in HIV-1 virion morphogenesis.

A large number of human immunodeficiency virus 1 (HIV-1) integrase (IN) alterations, referred to as class II substitutions, exhibit pleiotropic effects during virus replication. However, the underlying mechanism for the class II phenotype is not known. Here we demonstrate that all tested class II IN substitutions compromised IN-RNA binding in virions by one of the three distinct mechanisms: (i) markedly reducing IN levels thus precluding the formation of IN complexes with viral RNA; (ii) adversely affecting functional IN multimerization and consequently impairing IN binding to viral RNA; and (iii) directly compromising IN-RNA interactions without substantially affecting IN levels or functional IN multimerization. Inhibition of IN-RNA interactions resulted in the mislocalization of viral ribonucleoprotein complexes outside the capsid lattice, which led to premature degradation of the viral genome and IN in target cells. Collectively, our studies uncover causal mechanisms for the class II phenotype and highlight an essential role of IN-RNA interactions for accurate virion maturation.

Going beyond Integration: The Emerging Role of HIV-1 Integrase in Virion Morphogenesis.

The HIV-1 integrase enzyme (IN) plays a critical role in the viral life cycle by integrating the reverse-transcribed viral DNA into the host chromosome. This function of IN has been well studied, and the knowledge gained has informed the design of small molecule inhibitors that now form key components of antiretroviral therapy regimens. Recent discoveries unveiled that IN has an under-studied yet equally vital second function in human immunodeficiency virus type 1 (HIV-1) replication. This involves IN binding to the viral RNA genome in virions, which is necessary for proper virion maturation and morphogenesis. Inhibition of IN binding to the viral RNA genome results in mislocalization of the viral genome inside the virus particle, and its premature exposure and degradation in target cells. The roles of IN in integration and virion morphogenesis share a number of common elements, including interaction with viral nucleic acids and assembly of higher-order IN multimers. Herein we describe these two functions of IN within the context of the HIV-1 life cycle, how IN binding to the viral genome is coordinated by the major structural protein, Gag, and discuss the value of targeting the second role of IN in virion morphogenesis.

Why Go NANO on COVID-19 Pandemic?

Although treating COVID-19 is shown to be challenging, NANOtechnology is around the corner to overcome potential drawbacks. The use of NANOtechnologies will definitely shape the worldwide approaches and tools to treat COVID-19. Here we highlight the importance of going NANO on the COVID-19 pandemic.

Tandem Bioorthogonal Labeling Uncovers Endogenous Cotranslationally O-GlcNAc Modified Nascent Proteins.

Hundreds of nuclear, cytoplasmic, and mitochondrial proteins within multicellular eukaryotes have hydroxyl groups of specific serine and threonine residues modified by the monosaccharide N-acetylglucosamine (GlcNAc). This modification, known as O-GlcNAc, has emerged as a central regulator of both cell physiology and human health. A key emerging function of O-GlcNAc appears to be to regulate cellular protein homeostasis. We previously showed, using overexpressed model proteins, that O-GlcNAc modification can occur cotranslationally and that this process prevents premature degradation of such nascent polypeptide chains. Here, we use tandem metabolic engineering strategies to label endogenously occurring nascent polypeptide chains within cells using O-propargyl-puromycin (OPP) and target the specific subset of nascent chains that are cotranslationally glycosylated with O-GlcNAc by metabolic saccharide engineering using tetra-O-acetyl-2-N-azidoacetyl-2-deoxy-d-galactopyranose (Ac4GalNAz). Using various combinations of sequential chemoselective ligation strategies, we go on to tag these analytes with a series of labels, allowing us to define conditions that enable their robust labeling. Two-step enrichment of these glycosylated nascent chains, combined with shotgun proteomics, allows us to identify a set of endogenous cotranslationally O-GlcNAc modified proteins. Using alternative targeted methods, we examine three of these identified proteins and further validate their cotranslational O-GlcNAcylation. These findings detail strategies to enable isolation and identification of extremely low abundance endogenous analytes present within complex protein mixtures. Moreover, this work opens the way to studies directed at understanding the roles of O-GlcNAc and other cotranslational protein modifications and should stimulate an improved understanding of the role of O-GlcNAc in cytoplasmic protein quality control and proteostasis.

Emulsions Stabilised by Polyethylene Glycol (PEG) 40 Stearate and Lactoferrin for Protection of Lactoferrin during In Vitro Digestion

Polyethylene glycol (PEG) and its derivatives are widely used in delivery systems to protect bioactive peptides and proteins against premature degradation. In this study, we sought to understand whether or not bioactive proteins at the interface of emulsions can be protected by PEG chains during in vitro gastrointestinal digestion. We designed an emulsion stabilised by both PEG 40 stearate (PEG 40 St) and a bioactive protein, bovine lactoferrin (LF), and we monitored the fate of LF during in vitro digestion. The PEG–LF emulsions displayed a droplet diameter of 200 nm and remained colloidally and morphologically stable for at least 2 h in the simulated gastric fluid; in contrast, the control emulsions with LF alone showed droplet flocculation. After 2 h of gastric digestion, the LF in these emulsions was largely protected (84% remaining), whereas only 23% LF remained in the control emulsions. This protective effect on LF might be related to an inhibition of pepsin activity by PEG 40 St, independent of the location of the LF. Under intestinal conditions, the PEG–LF emulsions had good stability and slower lipolysis than the control emulsions, but LF was prone to immediate degradation within 5 min, regardless of the protection from PEG 40 St, suggesting that PEG 40 St had no inhibitory effect on pancreatic proteases. Overall, this work shows promise for using PEG 40 St, a food-grade emulsifier, to prevent premature gastric digestion of bioactive proteins following oral delivery.

Using X-ray microtomography to study the initiation of chloride-induced reinforcement corrosion in cracked concrete

Corrosion is the main cause of premature degradation of reinforced concrete structures. In particular, the mechanisms of chloride-induced corrosion in cracked structures are not fully elucidated. The aim of this study is to investigate by X-ray tomographic imaging the initiation and propagation of chloride-induced corrosion in cracked concrete. On reinforced prismatic cracked specimens exposed to seawater spray-drying cycles, the approach consists in characterizing in a non-destructive way the crack geometry, corroded steel volume and corrosion products migrating in the cementitious matrix and crack, as a function of time. Sub-volume scans and difference images allow a study of the first stage of chloride-induced corrosion in cracked concrete with respect to the number of spraying cycles, geometry and crack opening. The volume of steel consumed measured by 3D imaging is validated against destructive measurements, and it is shown that insights about the phenomenology of pitting (depth, displacement of corrosion products, densification, crack clogging…) can be obtained.

Conjugation of Doxorubicin to siRNA Through Disulfide-based Self-immolative Linkers.

Co-delivery systems of siRNA and chemotherapeutic drugs have been developed as an attractive strategy to optimize the efficacy of chemotherapy towards cancer cells with multidrug resistance. In these typical systems, siRNAs are usually associated to drugs within a carrier but without covalent interactions with the risk of a premature release and degradation of the drugs inside the cells. To address this issue, we propose a covalent approach to co-deliver a siRNA-drug conjugate with a redox-responsive self-immolative linker prone to intracellular glutathione-mediated disulfide cleavage. Herein, we report the use of two disulfide bonds connected by a pentane spacer or a p-xylene spacer as self-immolative linker between the primary amine of the anticancer drug doxorubicin (Dox) and the 2′-position of one or two ribonucleotides in RNA. Five Dox-RNA conjugates were successfully synthesized using two successive thiol-disulfide exchange reactions. The Dox-RNA conjugates were annealed with their complementary strands and the duplexes were shown to form an A-helix sufficiently stable under physiological conditions. The enzymatic stability of Dox-siRNAs in human serum was enhanced compared to the unmodified siRNA, especially when two Dox are attached to siRNA. The release of native Dox and RNA from the bioconjugate was demonstrated under reducing conditions suggesting efficient linker disintegration. These results demonstrate the feasibility of making siRNA-drug conjugates via disulfide-based self-immolative linkers for potential therapeutic applications.

Generation Units Maintenance in Combined Heat and Power Integrated Systems Using the Mixed Integer Quadratic Programming Approach

Yearly generation maintenance scheduling (GMS) of generation units is important in each system such as combined heat and power (CHP)-based systems to decrease sudden failures and premature degradation of units. Imposing repair costs and reliability deterioration of system are the consequences of ignoring the GMS program. In this regard, this research accomplishes GMS inside CHP-based systems in order to determine the optimal intervals for predetermined maintenance required duration of CHPs and other units. In this paper, cost minimization is targeted, and violation of units’ technical constraints like feasible operation region of CHPs and power/heat demand balances are avoided by considering related constraints. Demand-response-based short-term generation scheduling is accomplished in this paper considering the maintenance intervals obtained in the long-term plan. Numerical simulation is performed and discussed in detail to evaluate the application of the suggested mixed-integer quadratic programming model that implemented in the General Algebraic Modeling System software package for optimization. Numerical simulation is performed to justify the model effectiveness. The results reveal that long-term maintenance scheduling considerably impacts short-term generation scheduling and total operation cost. Additionally, it is found that the demand response is effective from the cost perspective and changes the generation schedule.

A critical review on the durability of geopolymer composites in acidic environment

Deterioration of concrete in acidic environments result in premature degradation in terms of microstructural alteration of phases leading to mass changes, weakening of mechanical properties, increase in porosity due to calcium leaching etc. Industries are found to dispose acidic effluents directly into the environment without proper treatments. Again, these acids can be organic as well as inorganic acids. Organic acids unlike inorganic acids are found to be weak acids due to their partly dissociative nature. The mechanism of acid attack varies based on the acid type and the characteristics of the calcium salt that are formed. Conventional concrete made with Ordinary Portland Cement (OPC) are not resistant to acids. Also, as we strive towards sustainable development, alkali activated or geopolymer concrete has started to gain attention as it is found to have better mechanical properties and durability comparing to conventional concrete. This paper reviews the damage mechanisms of sulphuric acid, citric acid, nitric acid and acetic acid on the alkali activated binders.