Temperature-sensitive Process Research Articles

Heat stress induced piRNA alterations in pachytene spermatocytes and round spermatids

BackgroundSpermatogenesis is a temperature-sensitive process, and elevation in temperature hampers this process quickly and significantly. We studied the molecular effects of testicular heating on piRNAs and gene expression in rat testicular germ cells.MethodsWe generated a cryptorchid rat model by displacing the testis from the scrotal sac (34 °C) to the abdominal area (37 °C) and sacrificed animals after 1 day, 3 days, and 5 days. Pachytene spermatocytes and round spermatids were purified using elutriation centrifugation and percoll gradient methods. We performed transcriptome sequencing in pachytene spermatocytes and round spermatids to identify differentially expressed piRNAs and their probable targets, i.e., TE transcripts and mRNAs.ResultsAs a result of heat stress, we observed significant upregulation of piRNAs and TE transcripts in testicular germ cells. In addition to this, piRNA biogenesis machinery and heat shock proteins (Hsp70 and Hsp90 family members) were upregulated. mRNAs have also been proposed as targets for piRNAs; therefore, we shortlisted certain piRNA-mRNA pairs with an inverse relationship of expression. We observed that in testicular heat stress, the heat shock proteins go hand-in-hand with the upregulation of piRNA biogenesis machinery. The dysregulation of piRNAs in heat-stressed germ cells, increased ping-pong activity, and disturbed expression of piRNA target transcripts suggest a connection between piRNAs, mRNAs, and TE transcripts.ConclusionsIn heat stress, piRNAs, piRNA machinery, and heat shock proteins are activated to deal with low levels of stress, which is followed by a rescue approach in prolonged stressaccompained by high TE activity to allow genetic mutations, perhaps for survival and adaptability.

Model-based assessment of in-sewer heat recovery potentials considering wastewater treatment-specific temperature limits

ABSTRACT Due to the ongoing climate and energy crisis, wastewater is becoming increasingly important as a source of renewable energy. In urban areas, heat recovery from the sewer is considered a promising approach, as the locations of supply and demand are close to each other. In this context, it is crucial that negative impacts on temperature-sensitive processes in the downstream wastewater treatment plant are strictly avoided. To support the necessary planning and authorization, this paper presents a model-based approach to assess the thermal energy level of the wastewater at any given location in the sewer, taking into account the influent temperature constraints of the wastewater treatment plant. The entire modelling is based on the open-source software SWMM 5, which was extended by a temperature model. The concept showed its practicability and informative value during a full-scale field application in the sewer systems of the Austrian city of Graz. All modelling is based on freely available software, which makes the approach easy transferable to other cities with comparable infrastructural boundary conditions.

Continuous flow synthesis enabling reaction discovery.

This article defines the role that continuous flow chemistry can have in new reaction discovery, thereby creating molecular assembly opportunities beyond our current capabilities. Most notably the focus is based upon photochemical, electrochemical and temperature sensitive processes where continuous flow methods and machine assisted processing can have significant impact on chemical reactivity patterns. These flow chemical platforms are ideally placed to exploit future innovation in data acquisition, feed-back and control through artificial intelligence (AI) and machine learning (ML) techniques.

Effect of thermal acclimation on the tolerance of the peach fruit fly (Bactrocera zonata: Tephritidae) to heat and cold stress

Understanding the thermal biology of insects is of increasing importance for predicting their geographic distribution, particularly in light of current and future global temperature increases. Within the limits set by genetic makeup, thermal tolerance is affected by the physiological conditioning of individuals (e.g., through acclimation). Considering this phenotypic plasticity may add to accurately estimating changes to the distribution of insects under a changing climate.We studied the effect of thermal acclimation on cold and heat tolerance of the peach fruit fly (Bactrocera zonata) – an invasive, polyphagous pest that is currently expanding through Africa and the Middle East. Females and males were acclimated at 20, 25 and 30 °C for up to 19 days following adult emergence. The critical thermal minimum (CTmin) and maximum (CTmax) were subsequently recorded as well adult survival following acute exposure to chilling (0 or −3 °C for 2 h). Additionally, we determined the survival of pupae subjected for 2 h to temperatures ranging from −12 °C to 5 °C.We demonstrate that acclimation at 30 °C resulted in significantly higher CTmax and CTmin values (higher heat resistance and lower cold resistance, respectively). Additionally, adult recovery following exposure to −3 °C was significantly reduced following acclimation at 30 °C, and this effect was significantly higher for females. Pupal mortality increased with the decrease in temperature, reaching LT50 and LT95 values following exposure to -0.32 °C and −6.88 °C, respectively. Finally, we found that the survival of pupae subjected to 0 and 2 °C steadily increased with pupal age.Our findings substantiate a physiological foundation for understanding the current geographic range of B. zonata. We assume that acclimation at 30 °C affected the thermal tolerance of the flies partly through modulating feeding and metabolism. Tolerance to chilling during the pupal stage probably changed according to temperature-sensitive processes occurring during metamorphosis, rendering younger pupae more sensitive to chilling.

Keep cool! Observed temperature variations at different process stages of the biobanking workflow – examples from the Leipzig medical biobank

Abstract Objectives Biobanked samples are becoming increasingly important for research outcomes. Most of the biobanking processes (from preparation to storage) are affected by temperature in a time-dependent manner and have a high impact on sample quality. We aimed to validate time and temperature sensitive processes such as sample preparation, transport, sorting, and storage, which have a high impact on sample quality. Methods Temperature was measured using internal or external temperature data loggers. We analysed the temperature and present real data from our sample transport on dry ice and with the CryoPod, from our ultra-low temperature freezers (UTFs) of different manufacturers and cryostores. We also tested sample sorting on dry ice and in a cryogenic workbench. Results In the UTFs, we identified temperature zones with a temperature difference from 4.7 °C up to 20.8 °C across the whole UTF. For sample transport within approximately 30 min we observed temperatures of −80.2 °C ± 4.0 °C and −173.9 °C ± 16.9 °C for dry ice boxes and the CryoPod, respectively. Sorting on dry ice was best in a polystyrene box half-filled with dry ice pellets, although the temperature increased by 7.5 °C within the first 5 min, whereas the temperature in the cryogenic workbench remained stable below −100 °C for hours. Conclusions Time and temperature play a crucial role in the entire biobanking process, with sometimes immense temperature fluctuations in some equipment. We recommend the validation or verification of all equipment and processes used to avoid pre-analytical errors in accordance with DIN EN ISO 20387.

Cold-induced inhibition of photosynthesis-related genes integrated by a TOP6 complex in rice mesophyll cells.

Photosynthesis is the most temperature-sensitive process in the plant kingdom, but how the photosynthetic pathway responds during low-temperature exposure remains unclear. Herein, cold stress (4°C) induced widespread damage in the form DNA double-stranded breaks (DSBs) in the mesophyll cells of rice (Oryza sativa), subsequently causing a global inhibition of photosynthetic carbon metabolism (PCM) gene expression. Topoisomerase genes TOP6A3 and TOP6B were induced at 4°C and their encoded proteins formed a complex in the nucleus. TOP6A3 directly interacted with KU70 to inhibit its binding to cold-induced DSBs, which was facilitated by TOP6B, finally blocking the loading of LIG4, a component of the classic non-homologous end joining (c-NHEJ) pathway. The repression of c-NHEJ repair imposed by cold extended DSB damage signaling, thus prolonging the inhibition of photosynthesis in leaves. Furthermore, the TOP6 complex negatively regulated 13 crucial PCM genes by directly binding to their proximal promoter regions. Phenotypically, TOP6A3 overexpression exacerbated the γ-irradiation-triggered suppression of PCM genes and led to the hypersensitivity of photosynthesis parameters to cold stress, dependent on the DSB signal transducer ATM. Globally, the TOP6 complex acts as a signal integrator to control PCM gene expression and synchronize cold-induced photosynthesis inhibition, which modulates carbon assimilation rates immediately in response to changes in ambient temperature.

EPFL peptide signalling ensures robust self-pollination success under cool temperature stress by aligning the length of the stamen and pistil.

Successful sexual reproduction of plants requires temperature-sensitive processes, and temperature stress sometimes causes developmental asynchrony between male and female reproductive tissues. In Arabidopsis thaliana, self-pollination occurs when the stamen and pistil lengths are aligned in a single flower so that pollens at the stamen tip are delivered to the stigma at the pistil tip. Although intercellular signalling acts in several reproduction steps, how signalling molecules, including secreted peptides, contribute to the synchronous growth of reproductive tissues remains limited. Here, we show that the mutant of the secreted peptide EPIDERMAL PATTERNING FACTOR LIKE 6 (EPFL6), which shows no phenotypes at a moderate temperature, fails in fruit production at a cool temperature due to insufficient elongation of stamens. EPFL6 is expressed in stamen filaments and promotes filament elongation to achieve the alignment of stamen and pistil lengths at a cool temperature. We also found that, at a moderate temperature, all EPFL6-subfamily genes are required for stamen elongation. Furthermore, we showed that ERECTA (ER), known as a common receptor for EPFL-family peptides, mediates the stamen-pistil growth coordination. Lastly, we provided evidence that modulation of ER activity rescues the reproduction failure caused by insufficient stamen elongation by realigning the stamen and pistil lengths.

Thin PDMS-on-Sacrificial-PCB Devices

Poly(dimethylsiloxane) (PDMS) devices must often be so thin (e.g., <100 μm) and, therefore, so fragile that their mechanical release becomes challenging. As a simple solution, PDMS devices are frequently released by dissolving an underlying sacrificial resist. However, there may be several other issues, including temperature gradients during fabrication, electrical characterization, handling, co-integration with electronics, fabrication time, and cost. Here, we show that conventional printed circuit boards (PCBs) can be ideal sacrificial carriers, which can also perform useful functions during fabrication. The thick (e.g., 35 μm) and thermally conductive PCB copper layer behaves as an excellent heat spreading plate during temperature-sensitive process steps (e.g., PDMS curing and sintering of conductive inks) and enables pre-release electrical stimulations and characterizations of PDMS, which may help during process development. Experiments and finite element method (FEM) simulations confirm that the PCB copper layer can improve temperature uniformity. The UV-protecting film attached to the PCB can be cut to constitute a frame for easy handling. The PCB photoresist enables the straightforward release of PDMS by acetone, which is among the most environmentally friendly chemicals. Contacts can be opened by a simple bump-cut-peel strategy. As proofs of concept, we demonstrate pre-release capacitive characterization of PDMS for evaluating the ability to fabricate thin, but uniform and robust devices and post-release resistive characterization of stretchable strain sensor or interconnects encapsulated in PDMS. The proposed approach is simple, cheap, and environmentally friendly, can improve temperature uniformity throughout the pre-release process steps, enables pre-release electrical characterizations, can simplify co-integration with electronics and can be generalized to other elastomers.

Top Down and Bottom Up Synthesized Graphene Quantum Dots As Nanothermometers For I n Vitro Imaging

Non-invasive temperature sensing is necessary to analyze biological processes occurring in the human body, including cellular enzyme activity, protein expression, and ion regulation. To probe temperature-sensitive processes at the nanoscale, novel luminescence nanothermometers are developed based on graphene quantum dots (GQDs) synthesized via top-down (RGQDs) and bottom-up (N-GQDs) approaches from reduced graphene oxide and glucosamine precursors, respectively. Because of their small 3–6 nm size, non-invasive optical sensitivity to temperature change, and high biocompatibility, GQDs enable biologically safe sub-cellular resolution sensing. Both GQD types exhibit temperature-sensitive yet photostable fluorescence in the visible and near-infrared for RGQDs, utilized as a sensing mechanism in this work. Distinctive linear and reversible fluorescence quenching by up to 19.3% is observed for the visible and near-infrared GQD emission in aqueous suspension from 25 °C to 49 °C. A more pronounced trend is observed with GQD nanothermometers internalized into the cytoplasm of HeLa cells as they are tested in vitro from 25 °C to 45 °C with over 40% quenching response. Our findings suggest that the temperature-dependent fluorescence quenching of bottom-up and top-down-synthesized GQDs studied in this work can serve as non-invasive reversible/photostable deterministic mechanisms for temperature sensing in microscopic sub-cellular biological environments. Figure 1

Relevance and Regulation of Alternative Splicing in Plant Heat Stress Response: Current Understanding and Future Directions

Alternative splicing (AS) is a major mechanism for gene expression in eukaryotes, increasing proteome diversity but also regulating transcriptome abundance. High temperatures have a strong impact on the splicing profile of many genes and therefore AS is considered as an integral part of heat stress response. While many studies have established a detailed description of the diversity of the RNAome under heat stress in different plant species and stress regimes, little is known on the underlying mechanisms that control this temperature-sensitive process. AS is mainly regulated by the activity of splicing regulators. Changes in the abundance of these proteins through transcription and AS, post-translational modifications and interactions with exonic and intronic cis-elements and core elements of the spliceosomes modulate the outcome of pre-mRNA splicing. As a major part of pre-mRNAs are spliced co-transcriptionally, the chromatin environment along with the RNA polymerase II elongation play a major role in the regulation of pre-mRNA splicing under heat stress conditions. Despite its importance, our understanding on the regulation of heat stress sensitive AS in plants is scarce. In this review, we summarize the current status of knowledge on the regulation of AS in plants under heat stress conditions. We discuss possible implications of different pathways based on results from non-plant systems to provide a perspective for researchers who aim to elucidate the molecular basis of AS under high temperatures.

Enhancement of resilience and quality of cold supply chain under the disruptions caused by COVID-19: A case of a developing country

Cold supply chain (CSC) comprises temperature-sensitive processes, starting from the supply of raw materials, manufacturing, and finally the delivery of finished goods to the end consumers via transport services. Pandemics such as COVID-19 pose threats to its overall functioning and to cater to this issue, the study will ensure the sustainable functioning of CSC by recommending resilience strategies. To do so, the COVID-19 disruptions in the CSC and the resilient sustainability strategies were collected via a vigorous literature review and were analyzed via a Fuzzy QFD technique. The results concluded “crisis simulation,” “identification and securing of logistics,” and “digitalization of cold supply chain” as the top three strategies to ensure the resilience of CSC under disruptions caused by COVID-19. The study recommends necessary steps to the policymakers to ensure a resilient and quality effective CSC. The application of the study proves to be the first of its kind in a developing country such as Pakistan. JEL Classification: C54, D81, H12

Pore-scale observations of natural hydrate-bearing sediments via pressure core sub-coring and micro-CT scanning

Both intra-pore hydrate morphology and inter-pore hydrate distribution influence the physical properties of hydrate-bearing sediments, yet there has been no pore-scale observations of hydrate habit under pressure in preserved pressure core samples so far. We present for the first time a pore-scale micro-CT study of natural hydrate-bearing cores that were acquired from Green Canyon Block 955 in UT-GOM2-1 Expedition and preserved within hydrate pressure–temperature stability conditions throughout sub-sampling and imaging processes. Measured hydrate saturation in the sub-samples, taken from units expected to have in-situ saturation of 80% or more, ranges from 3 ± 1% to 56 ± 11% as interpreted from micro-CT images. Pore-scale observations of gas hydrate in the sub-samples suggest that hydrate in silty sediments at the Gulf of Mexico is pore-invasive rather than particle displacive, and hydrate particles in these natural water-saturated samples are pore-filling with no evidence of grain-coating. Hydrate can form a connected 3D network and provide mechanical support for the sediments even without cementation. The technical breakthrough to directly visualize particle-level hydrate pore habits in natural sediments reported here sheds light on future investigations of pressure- and temperature-sensitive processes including hydrate-bearing sediments, dissolved gases, and other biochemical processes in the deep-sea environment.

Impacts of thermo-optical properties on the seasonal operation of thermochromic smart window

A type of smart window using thermochromic glazing (TCG) is a promising technology for green buildings owing to the self-regulating feature and low-maintenance need. Its most important feature, thermo-optical properties that regulate the blockage of solar heat, is directly linked to the variation of surface temperatures. However, challenges from the inhomogeneity of thermo-optical properties, the coupled solar radiation and natural convection, and varying outdoor conditions all seriously hinder the understanding of its mechanism. In this paper, a validated Computational Fluid Dynamics (CFD) model achieves the simulation of inhomogeneous tinting of TCG by defining the thermo-optical properties of each finite volume according to the surface temperature. Solar radiation and natural convection at outdoor, indoor and the cavity are solved to reflect glazing temperature more accurately. The case studies compared six different switching temperatures in the range of 20 ∼ 42.5 °C with a transition gradient of 10 °C. Averaged meteorological data for both summer and winter, sunny days and cloudy days are selected to present realistic climate impacts. The result reveals the overall saving in transmitted solar radiation in summer and heating penalties in winter. It suggests the best switching temperatures for each climate condition. With the seasonal operation, the highest saving in solar heat gain is 20.9% when adopting a switching temperature of 25–35 °C, while the lowest saving can be negative, meaning TCG is not suitable for those climate zones. The proposed evaluation criteria help to quantify the applicability of TCG with the input of the summer/winter day ratio and sunny/cloudy ratio. The best region to apply TCG is where summer days are longer and winter solar radiation is significantly lower. The in-depth understanding of this temperature-sensitive process benefits the optimization of TCG in buildings, especially for its seasonal operation needs.

Synthetic leptin c-fragment peptide minimises heat-induced impairment of spermatogenesis in mice via Stat3 signalling

Mammalian spermatogenesis is a temperature-sensitive process, and an increase in testicular temperature impairs spermatogenesis. Leptin modulates testicular activity, but the effect of leptin or its synthetic analogue on heat-induced testicular impairment is unclear. We investigated the effects of synthetic leptin peptide (116–130 amides) on testicular activity in heat-stressed mice model. 15 adult mice (25.54 ± 1.43 g) were selected for the study. Ten mice were subjected to a single heat stress treatment (HS) at 43 °C for 15 min by submerging the lower half of the body in a thermostatic water bath. After heat treatment, mice were divided into two groups, the heat-stressed HS group (n = 5) and the second group as HSL, treated with leptin peptide (116–130 amide) for 14 days. The HS group showed a significant (p < 0.05) decline in the GSI (0.25 ± 0.018), Johnsenscore (4.5 ±.19), seminiferous tubule diameter (160.75 ± 10.18 μm), germinal epithelium height, (GEH) (37.5 ± 1.59 μm) compared to the CN (GSI-0.37 ± 0.015; Johnsen score-7.9 ± 0.20; GEH- 73.25 ± 1.29 μm; tubule diameter-230.25 ± 1.39 μm) and the HSL groups (GSI-0.38 ± 0.014; Johnsen’ score-8.0 ± 0.32; GEH- 37.5 ± 1.59 μm; tubule diameter-160.75 ± 10.18 μm) groups. Heat treatment significantly (p < 0.05) increased the intra-testicular levels of leptin (HS-20.11 ± 2.1 pg/mg protein; CN-10.50 ± 0.17 pg/mg protein; HSL-12.99 ± 0.52 pg/mg protein) with a reduced level of pStat3, suggesting leptin resistance during testicular hyperthermia. Furthermore, heat treatment was associated with significantly (p < 0.05) decreased germ cell proliferation and reduced circulating testosterone levels (HS-2.69 ± 2.01 ng/mL; CN-7.69 ± 0.32 ng/mL; HSL-5.36 ± 0.73 ng/mL). However, the circulating androstenedione levels showed a significant (p < 0.05) increase in the HS group (0.75 ± 0.03 ng/mL) compared to the CN (0.51 ± 0.02 ng/mL) and HSL (0.57 ± 0.07 ng/mL) groups. Immunolocalisation of 3β−HSD showed moderate to faint staining in the Leydig cells in the HS group compared to the CN and HSL groups. Treatment with leptin peptide resulted in decrease in the intra-testicular leptin levels with increased phosphorylation of Stat3, suggesting improved leptin resistance, which was positively associated with increased germ cell proliferation, elevated testosterone levels, and improved testicular histoarchitecture. Testicular hyperthermia may cause leptin resistance and impaired leptin signalling, decreased testosterone biosynthesis and suppressed spermatogenesis, which could be a manifestation of leptin resistance. Treatment with leptin peptide improves leptin signalling and testicular activity in heat-stressed mice, but the underlying mechanism is still unclear.

Differences in lipid homeostasis and membrane lipid unsaturation confer differential tolerance to low temperatures in two Cycas species

BackgroundC. panzhihuaensis is more tolerant to freezing than C. bifida but the mechanisms underlying the different freezing tolerance are unclear. Photosynthesis is one of the most temperature-sensitive processes. Lipids play important roles in membrane structure, signal transduction and energy storage, which are closely related to the stress responses of plants. In this study, the chlorophyll fluorescence parameters and lipid profiles of the two species were characterized to explore the changes in photosynthetic activity and lipid metabolism following low-temperature exposure and subsequent recovery.ResultsPhotosynthetic activity significantly decreased in C. bifida with the decrease of temperatures and reached zero after recovery. Photosynthetic activity, however, was little affected in C. panzhihuaensis. The lipid composition of C. bifida was more affected by cold and freezing treatments than C. panzhihuaensis. Compared with the control, the proportions of all the lipid categories recovered to the original level in C. panzhihuaensis, but the proportions of most lipid categories changed significantly in C. bifida after 3 d of recovery. In particular, the glycerophospholipids and prenol lipids degraded severely during the recovery period of C. bifida. Changes in acyl chain length and double bond index (DBI) occurred in more lipid classes immediately after low-temperature exposure in C. panzhihuaensis compare with those in C. bifida. DBI of the total main membrane lipids of C. panzhihuaensis was significantly higher than that of C. bifida following all temperature treatments.ConclusionsThe results of chlorophyll fluorescence parameters confirmed that the freezing tolerance of C. panzhihuaensis was greater than that of C. bifida. The lipid metabolism of the two species had differential responses to low temperatures. The homeostasis and plastic adjustment of lipid metabolism and the higher level of DBI of the main membrane lipids may contribute to the greater tolerance of C. panzhihuaensis to low temperatures.

SONOGRAPHIC MEASUREMENTS OF SCROTAL WALL THICKNESS

Main function of scrotum is to hold testes at optimal temperature for spermatogenesis. Sperm production in the testes is a temperature sensitive process. It requires an environment that is 2 to 6°C cooler than the body core. The temperature of the testes is regulated by the scrotal wall. Tunica dartos muscle changes the surface area of the scrotal skin by contracting or relaxing depending on the ambient temperature. This study postulates that if the thickness or the tone of this muscle is more thereby contributing to scrotal wall thickening, it will hamper the thermoregulation and spermatogenesis leading to poor sperm production. This could be an besides varicocoele another cause of male infertility which has been an established cause. This study will help to suspect the patients of infertility caused by thick scrotal wall. This study is aimed to study scrotal wall thickness and with the help of Ultrasonography. to establish norms The study was conducted at department of Radio-diagnosis at the tertiary care hospital, Sangli. The study started after approval of institutional ethical committee. This is a cross sectional observational study for the duration of 4 months. Total number of 50 cases was achieved in this time duration which satised the inclusion criteria. Statistical method used was Student's T test. Scrotal ultrasonography was performed using linear and curvilinear probe with sta (5-12 MHz) (2-5 MHz) on Philips Afniti50, after ndoff pad allowing some time for the dartos muscle to relax and scrotal wall thickness is measured on either side on three surfaces (anterior, posterior and lateral) and means were obtained. This study found that there was no difference between anterior, posterior, lateral wall thicknesses on ipsilateral side or contralateral side. There is no need to take three different wall thicknesses and convenience and suitability of any scrotal wall thickness would be equally effective.

Nitrogen-Doped Graphene Quantum Dots and Reduced Graphene Oxide Quantum Dots As Intracellular Temperature Sensors

Non-invasive temperature sensing is necessary for the analysis of biological processes occurring in the human body including cellular enzyme activity, protein expression, and ion regulation. In order to probe temperature-sensitive processes at the nanoscale we develop novel luminescence nanothermometers based on graphene quantum dots (GQDs) synthesized via top-down (RGQDs) and bottom-up (N-GQDs) approaches from reduced graphene oxide and glucosamine precursors. Because of their small 3-6 nm size, non-invasive optical sensitivity to temperature change, and high biocompatibility, GQDs enable biologically safe sub-cellular resolution sensing. Both GQD types exhibit temperature-sensitive, yet photostable fluorescence in the visible and near-infrared for RGQDs, utilized as a sensing mechanism in this work. Distinctive linear and reversible fluorescence quenching with temperature by up to 19.3 % is observed for the visible and near-infrared GQD emission in aqueous suspension, in a small temperature range from 25 to 49℃. An even more pronounced trend is observed with GQD nanothermometers internalized into the cytoplasm of HeLa cells as they are tested in vitro in the temperature range of 25℃ to 45℃ with over 40% quenching response. Our findings suggest that the temperature-dependent fluorescence quenching of bottom-up and top-down-synthesized GQDs studied in this work can serve as non-invasive reversible photostable deterministic mechanism for temperature sensing in microscopic sub-cellular biological environments.

Graphene Quantum Dots as Intracellular Imaging-Based Temperature Sensors.

Non-invasive temperature sensing is necessary to analyze biological processes occurring in the human body, including cellular enzyme activity, protein expression, and ion regulation. To probe temperature-sensitive processes at the nanoscale, novel luminescence nanothermometers are developed based on graphene quantum dots (GQDs) synthesized via top-down (RGQDs) and bottom-up (N-GQDs) approaches from reduced graphene oxide and glucosamine precursors, respectively. Because of their small 3–6 nm size, non-invasive optical sensitivity to temperature change, and high biocompatibility, GQDs enable biologically safe sub-cellular resolution sensing. Both GQD types exhibit temperature-sensitive yet photostable fluorescence in the visible and near-infrared for RGQDs, utilized as a sensing mechanism in this work. Distinctive linear and reversible fluorescence quenching by up to 19.3% is observed for the visible and near-infrared GQD emission in aqueous suspension from 25 °C to 49 °C. A more pronounced trend is observed with GQD nanothermometers internalized into the cytoplasm of HeLa cells as they are tested in vitro from 25 °C to 45 °C with over 40% quenching response. Our findings suggest that the temperature-dependent fluorescence quenching of bottom-up and top-down-synthesized GQDs studied in this work can serve as non-invasive reversible/photostable deterministic mechanisms for temperature sensing in microscopic sub-cellular biological environments.

Development of a form-flexible handling technology with active cooling for hybrid components in forging processes

Tailored Forming is a novel manufacturing process for the production of forged hybrid components. In contrast to components made of mono-materials, hybrid components can be adapted to the respective loads by combining different materials with contradictory properties. Short processing times and high component quality, however, lead to the demand for automated handling and local active cooling within the forming process, since the appropriate processing temperature is particularly important. Due to the fact that the hybrid components are differently hot and change their shape during the forming process, a special gripper system must be provided, which can withstand high temperatures, and ensures both shape variability and local cooling. Nowadays, however, there is a gap between shape variable grippers and rigid grippers for temperature-sensitive processes without any integrated cooling functionalities. Therefore, this paper presents an approach for the development of shape variable high temperature grippers with the use-case of handling hot steel-aluminium hybrid components.

Effect of Temperature and Residence Time Torrefaction Palm Kernel Shell On The Calorific Value and Energy Yield

Torrefaction was thermochemical processes to make biomass a fuel that had better properties, such as increased carbon content and calorific value. It was a temperature-sensitive process that was effective between 200 °C and 300 °C in an inert environment with a residence time of 20-60 minutes. Palm kernel shell was one of the biomass that has the potential to be used as fuel, where its availability was abundant and has good physical properties. In this study of palm kernel shell torrefaction was carried out from 0.5 cm sieve with three variations in temperature and residence time follows 250 °C - 300 °C and 20-40 minutes. The results obtained were the increase in temperature and holding time causes an increase in the calorific value but relatively on energy yield because of a large mass loss at a temperature of 300 °C. The optimum process for torrefaction of palm kernel shell according to calorific value and energy yield was 275 °C with residence time 20 minutes.