Curcuma longed L.  is one of the major species of Yujin. According to the processing theory of TCM, stir-frying HSYJ with vinegar might strengthen the effect of dispersing stagnated hepatoqi to relieve pain, and stir-frying HSYJ with wine might strengthen the effect of promoting blood circulation in order to remove blood stasis. However, the mechanism for the enhancement of clinical efficacy by processing is unclear.Curcumae blood Radix (Yujin) has been widely used to treat Qi stagnation and stasis in TCM. According to the Chinese Pharmacopoeia, the tuberous roots of This study was aimed at evaluating the effect of different processed products of HSYJ on chemical constituents and pain-related substances to explore underlying mechanisms of HSYJ in treating pain caused by Qi stagnation and blood stasis.The effects of different processing methods on the paste yield of water decoction were analyzed, and the content of the main constituents were detected by HPLC. A rat model of Qi stagnation and blood stasis was established by tail clamp stimulation combined with subcutaneous adrenaline injection. After treatment and intervention with HSYJ and its processed products, β-endorphin (β-EP) and 5-hydroxytryptamine (5-HT) were measured by ELISA, and the expression of c-fos was evaluated by immunohistochemistry.P < 0.05) and β-EP in brain (P < 0.01). Stir-frying HSYJ with vinegar or wine could significantly improve the abnormality of 5-HT in plasma, β-EP in brain, and the expression of c-fos (P < 0.01). Stir-frying HSYJ with vinegar could also significantly increase the level of β-EP in plasma (P < 0.05).After stir-frying with vinegar or wine, the extract yield and curcumin content increased. Compared with model group, raw HSYJ could significantly improve the abnormality of 5-HT in plasma (These results showed that different processing methods have certain effects on the chemical constituents of HSYJ, mainly in increasing the decoction rate and curcumin content. HSYJ and its processed products can reduce 5-HT levels, increase β-EP levels, and inhibit the expression of c-fos in model rats. The effects of stir-frying HSYJ with vinegar on β-EP levels in plasma was superior to others. Curcuma wenyujin Y. H. Chen et C. Ling, Curcuma longa L., Curcuma kwangsiensis S. G. Lee et C. F. Liang, or Curcuma phaeocaulis Val. The drugs derived from the former two are known as “Wenyujin” and “Huangsiyujin,” respectively, and the drugs derived from the others are known as “Guiyujin” and “Lüsiyujin,” respectively, according to their different appearances. As one of the major species of Curcumae Radix, Huangsiyujin (HSYJ) is a well-known genuine traditional Chinese medicine in Sichuan. Its properties include activating blood, relieving pain, moving Qi, relieving depression, clearing the heart, cooling the blood, disinhibiting the gallbladder, and abating jaundice (Curcumae Radix (Yujin) is the dried root tuber of jaundice . It is wjaundice . Modern jaundice , easing jaundice , causingjaundice , as welljaundice , antidepjaundice .The processing technology of Chinese herbal medicines is a traditional pharmaceutical technology based on the basic theory of TCM; this takes into consideration the differentiation of symptoms and the nature of drugs as well as the different requirements of dispensation and preparation. It is an important part of TCM, which has been accumulated and developed in clinical practice by TCM physicians. According to the processing theory of TCM, raw Yujin is good at relieving depression, by soothing the liver to regulate Qi, and relieving pain, by promoting blood circulation to remove blood stasis. Stir-frying with vinegar can concentrate the effects on liver meridian to strengthen the effect of dispersing stagnated hepatoqi to relieve pain; stir-frying with wine strengthens the effect of promoting blood circulation to remove blood stasis .In an earlier study, we found that HSYJ could increase the pain threshold, prolong latency of twisting, decrease writhing times, and influence hemorheology . Its proThe reference standards of curcumin, demethoxycurcumin, and bisdemethoxycurcumin (purity > 98%) were purchased from the National Institutes for Food and Drug Control . Methanol and acetonitrile  were of high-performance liquid chromatography (HPLC) grade. Other reagents were of analytical purity. Water was glass distilled and filtered through a Milli-Q water purification system  prior to use.SPF-grade Sprague-Dawley rats (200 ± 20 g) were obtained from Chengdu Dashuo Experimental Animal Co., Ltd. . Animals were housed in polypropylene cages and were sent to an animal room 5 days in advance for acclimatization . They were maintained under controlled conditions (a 12 h light-dark cycle at 22 ± 2°C) on a standard pellet diet and had free access to water. Animal experiments were approved by the Committee of Scientific Research and the Committee of Animal Care of Chengdu University of Traditional Chinese Medicine .Curcuma longa L. by Professor LI Min . The sample information is shown in Medicinal materials were collected from the genuine producing areas and authenticated as the dried root tuber of Xuefu Zhuyu Pian (Lot:170409) was purchased from Weifang Zhongshi Pharmaceutical Co., Ltd. . Epinephrine Hydrochloride Injection (Lot:170507) was purchased from Grand Pharma (China) Co., Ltd. .Prepared slices of HSYJ was processed according to the Pharmacopeia of the People’s Republic of China (Vision 2015)  and the Raw HSYJ was washed clean, moistened thoroughly, cut into slices, and dried.We took slices HSYJ, mixed them with a certain amount of rice vinegar evenly, moistened them thoroughly until the vinegar was absorbed completely, poured the drugs into a frying container, and fried them for 10 min (temperature 120–150°C) before we took them out and laid them down to cool. The amount used was 100 kg drugs with 15 kg vinegar. The vinegar was diluted with the same volume of water.We took slices HSYJ, mixed them with a certain amount of yellow wine evenly, moistened them thoroughly until the wine was absorbed completely, poured the drugs into a frying container, and fried them for 10 min (temperature 120–150°C) before we took them out and laid them down to cool. The amount used was 100 kg drugs with 10 kg wine. The wine was diluted with 1.5-fold water.The decoction was prepared according to the Standard for Management of TCM Decocting Room in Medical Institutions and Technical Requirements for Quality Control and Standard Formulation of TCM Granules.–1 according to the conversion of human clinical dosage.HSYJ and its processed products were boiled for 30 min after soaking for 30 min with nine times the amount of water before being filtered. The dregs were boiled twice with seven times the amount of water for 30 min each time, and they were then filtered and mixed with the previous filtrate. The mixed decoction was concentrated by vacuum concentration (T ≤ 50°C). The dosage for rats was 0.9 g⋅kg–1 according to the conversion of human clinical dosage.A positive drug was prepared by grinding up Xuefu Zhuyu Pian and dissolving this in water. The dosage given to the rat was 0.432 g⋅kgWe took 50 mL of decoction and put it in an evaporating dish that had been dried to a constant weight. We then steamed it in a water bath, dried it in an oven at 105°C for 3 h, and cooled it in a dryer for 30 min. We then weighed it quickly and precisely and calculated the extraction yield. The extraction yield (%) of the sample was calculated with the dried product.We took 50 mL of decoction and steamed it in a water bath (T ≤ 60°C), dissolved it in methanol of a fixed volume of 10 mL. This was then shaken and filtered with a filter (0.45 μm pore size) prior to injection.–1; and the column temperature was 30°C.HPLC determinations were performed by using a SHIMADZU LC-2030C instrument  equipped with a DAD detector, an auto sampler, a column heater, and a SHIMADZU Shim-pack GIST C18  column. The mobile phase was acetonitrile-4% glacial acetic acid aqueous solution (48:52); the detection wavelength was 425 nm; the flow rate was 1 mL⋅minA total of 36 animals were randomly and equally divided into six groups : a control group (CG), model group (MG), Raw HSYJ group (SHG), Stir-frying HSYJ with vinegar group (CHG), Stir-frying HSYJ with wine group (JHG), and positive group (PoG). Except for the CG, the rest of the groups replicated the blood stasis model due to liver-Qi depression by the referenced methods . When thWe collected plasma using heparin as an anticoagulant and centrifuged it for 5 min at 3,000 rpm. The samples were stored in aliquot at −20°C for later use. We avoided repeated freeze-thaw cycles. Rat brain tissue samples were rinsed with normal saline and stored at −20°C. At the time of detection, rat liver tissue samples were thawed in 37°C water and weighed to the appropriate amount of tissue, ground with nine times the normal saline, and centrifuged for 10 min at 3,000 rpm. The supernatant was removed and assayed immediately. Rat 5-Hydroxytryptamine (5-HT) in plasma was detected with 5-HT ELISA Kit . Rat beta-endorphin (β-EP) in plasma and brain were detected with β-EP ELISA Kit .2O2 was 99:1) for 10 min at room temperature. Afterward, the slices were washed three times with PBS for 5 min each time. We then immersed them into 0.01M citrate buffer (PH 6.0), used high fire in a microwave oven to break off after boiling, and we repeated this one time after 5 min. After cooling, we washed them two times with PBS for 5 min each time. The slices were then incubated with normal goat serum  at room temperature for 20 min. The sections were incubated with primary antibody for c-fos  overnight at 4°C. The sections were then processed with the secondary antibody with goat anti-rabbit  for 30 min at 37°C. We washed them three times with PBS for 5 min each time. Used DAB  to develop color at room temperature, we controlled the reaction time under the microscope for 2 min and washed the sections with distilled water. Slices were slightly re-dyed with hematoxylin and sealed with neutral gum after dehydration and transparency.The fixed brain was dehydrated by an automatic dehydrator before being embedded and sliced. The devoted slices were put in the dye vat and performed in 3% hydrogen peroxide . The whole tissue was observed at 100 × magnification for each pathological section, and microscopic images were collected by selecting three fields of vision at 400 × magnification. Measured integrated optical density (IOD) and the area of all images by Image-Pro Plus 6.0  and calculated mean density (MD) of each image.post hoc multiple-comparison test by using SPSS 19.0 software. The P < 0.05 was considered to represent statistical significance.Statistical analyses were performed by repeating one-way analysis of variance (ANOVA), and this was followed by LSD’s The extraction yield was significantly increased after being stir-fried with vinegar or wine, but there was no significant difference between the stir-frying HSYJ with vinegar and stir-frying HSYJ with wine, indicating that processing could increase the dissolution of chemical constituents . Figure P < 0.01). After administration, HSYJ and its processed products could significantly improve 5-HT abnormality in plasma of model rats, but there was no difference between them.The results of changes to the 5-HT level are shown in P < 0.01). As an analgesic substance, the decrease of β-EP may be the mechanism behind Qi stagnation and blood stasis, causing pain. After administration, HSYJ and its processed products could improve β-EP abnormality in plasma and brain of model rats. Compared with MG, the β-EP in brain of HSYJ and its processed products increased significantly, and CHG and JHG were higher than those of GG. There was a significant difference between SHG and JHG. The results showed that HSYJ could enhance the analgesic effect by increasing the release of β-EP. The levels of β-EP in brain of drug groups were higher than that in CG, which may be due to the large release of β-EP in the brain in order to inhibit body pain. However, only the level of β-EP in plasma of CHG increased significantly, suggesting that stir-frying with vinegar not only increased the release of β-EP in brain but also promoted its entry into blood.The results of the changes to the β-EP level in plasma and brain are shown in P < 0.01). The indicator of the pain response is such that, the stronger the expression of c-fos, the stronger the pain the body experiences (P < 0.01), but there was no significant difference in SHG, which indicated that HSYJ could enhance the analgesic effect of the body by stir-frying with vinegar or wine. There was, however, no significant difference in the administration groups.The results of the expression of c-fos in the brain of rats are shown in eriences . After aAs a unique pharmaceutical technology in China, the processing technology of Chinese herbal medicines plays an important role in improving the clinical efficacy of traditional Chinese medicine. Physical and chemical changes of Chinese Materia Medica will occur in the course of processing, and the pharmacological effects will be changed because of these changes, thus resulting in different clinical significance. Huangsiyujin, as a common medicine for Qi stagnation and blood stasis in TCM clinic, has a variety of processed products. Their functions are also dissimilar. However, few scholars have studied the differences of chemical constituents and pharmacodynamics of different processed products of HSYJ.Traditional Chinese medicine clinically uses decoctions as medicines. In a broad sense, the extraction yield of decoctions can be used as one of the indexes to evaluate the quality of prepared slices of Chinese crude drugs. Modern research showed  that volThe theory of TCM argues that stagnation of Qi may bring about pain. 5-HT is a strong pain-inducing substance , 2018. TThis study indicated that different processing methods have certain effects on the chemical constituents of HSYJ, and this is achieved mainly through increasing the extraction yield and content of bisdemethoxycurcumin, demethoxycurcumin, and curcumin. Modern research showed that curcumin might play an analgesic role through a variety of mechanisms and alleviate different types of pain. HSYJ and its processed products may alleviate pain by regulating the release of 5-HT, increasing the content of β-EP and inhibiting the expression of c-fos. Stir-frying HSYJ with vinegar is more conducive to the release and blood entry of β-EP, thus enhancing the analgesic effect of the body, which is consistent with the traditional Chinese medicine theory of “stir-frying with vinegar into liver to strengthen the effect of dispersing stagnated hepatoqi to relieve pain.”The datasets generated for this study are available on request to the corresponding author.This study was conducted in strict accordance with the recommendations of the Guidelines for the Care and Use of Laboratory Animals of the Ministry of Science and Technology of China. The protocol was approved by the Committee of Animal Care of Chengdu University of Traditional Chinese Medicine .ZC overall responsibility for the manuscript. LH revised the manuscript and polished the language. YL, XZ, ZY, and LY performed the experiments. CH was involved in the design of the research.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


This paper presents a new A-weighting filter’s design and explores the potential of using approximate multiplication for low-power digital A-weighting filter implementation. It presents a thorough analysis of the effects of approximate multiplication, coefficient quantization, the order of first-order sections in the filter’s cascade, and zero-pole pairings on the frequency response of the digital A-weighting filter. The proposed A-weighting filter was implemented as a sixth-order IIR filter using approximate odd radix-4 multipliers. The proposed filter was synthesized (Verilog to GDS) using the Nangate45 cell library, and MATLAB simulations were performed to verify the designed filter’s magnitude response and performance. Synthesis results indicate that the proposed design achieves nearly 70% reduction in energy (power-delay product) with a negligible deviation of the frequency response from the floating-point implementation. Experiments on acoustic noise suggest that the proposed digital A-weighting filter can be deployed in environmental noise measurement applications without any notable performance degradation. Noise pollution is a common problem in urban environments. Humans are continuously exposed to noise as they go about their daily lives. However, exposure to noise in the urban environment or in the workplace can be a source of discomfort leading to health-related problems such as hearing loss if the correct protective actions are not taken. In order to assess the risk of noise for humans, one course of action is to measure the noise level present in the humans’ living and working environments. Typical environmental or background noise levels in residential areas range from 30 to 80 dB, and long-term exposure to sound levels over 85 dB causes hearing damage . StudiesIn order to measure human exposure to noise, the measurement equipment must correlate the measured sound pressure level (SPL) to the perceived loudness level of noise using weighting filters, such as an A-weighting filter. An A-weighting filter for sound level meters is defined in the International standard IEC 61672-1  and is rAn A-weighting filter can be implemented as an analog or digital filter. Digital filters can achieve far superior results to those of analog filters, as they do not suffer from parasitic or temperature variations that affect analog filters. Besides, the implementation of digital filters in digital systems , which are omnipresent in today’s measurement equipment, sensor nodes, and edge devices, is straightforward.Coefficients of digital filters obtained from transfer functions of analog filters are real numbers that require an infinite number of bits for their representations, or at least a floating-point representation in digital systems. In practical situations, it is impossible to represent a digital filter’s coefficients with an infinite number of bits; hence, designers generally use fixed-point approaches to represent the filter’s coefficients. Unfortunately, fixed-point designs degrade the filter frequency response and introduce a theoretical limit of the filter’s performance . For exaThe interest in reducing the power consumption of digital filters used in edge computing and sensor networks is growing rapidly. Several techniques are used to achieve significant reductions in power consumption. One of the first papers proposing approximate processing to achieve these goals is ; there tThe effectiveness of approximate multipliers for achieving low-power processing motivated us to apply approximate multiplication inside the A-weighting filter. The main idea was to introduce approximate multiplication in an A-weighting IIR filter and save the area and energy while introducing a neglectable computational error. This work is motivated by some earlier works in which the approximate multiplication was used in finite impulse response (FIR) filters ,17,18,19This paper presents a new design for an approximate low-power digital A-weighting filter implemented as a sixth-order IIR filter with approximate multipliers.This work provides a thorough analysis of the effects of approximate multiplication on the frequency response of an A-weighting IIR filter. We show how the optimal placement of approximate multipliers across the filter and the appropriate zero-pole pairings ensure minimal degradation of the filter’s frequency response in the presence of approximate multiplication.Synthesis results indicate that the proposed approximate IIR filter design achieves a nearly 70% reduction in energy (power-delay product) while preserving the required accuracy.The contributions of this paper can be summarized as follows:The rest of the manuscript is organized as follows. The human auditory system responds to air pressure changes, which are perceived as sound. Therefore, in order to quantify the sound level, it is convenient to measure the pressure of the sound wave at the location of the listener. The sound pressure level is computed as the root-mean-square (RMS) value of the sound pressure, p over a given interval of time. The RMS value of the sound pressure is defined asReference value T are adopted in sound level measurements, namely, impulse (I), fast (F), and slow (S) averaging with time constants equal to 35, 125, and 1 s, respectively [Since the root mean square computation in Equation  involvesectively .The human auditory system has a more pronounced response to signals in the frequency range between 500 and 8 kHz and is less sensitive to very low-pitch and high-pitch noises. To ensure that a sound level meter measures close to what a human hears, the correct frequency weighting related to the response of the human auditory system must be used in sound level measurement. The A-weighting filter  is desigThe A-weighting filter, whose magnitude response is presented in Most of the previous work on noise measurement ,26,27,28Many DSP applications use distributed arithmetic based approximate structures for efficient implementation of inner products. In the existing literature, most of these approximate architectures are developed by truncating the least significant bits (LSBs) of the inputs or filter coefficients ,19,30,31The paper  tries toVolkova et al.  proposedHowever, there is no thorough analysis of the effect of approximate multiplication, quantization, and zero-pole pairings in the IIR digital filters, as we show in this work.A digital A-weighting filter is implemented as infinite impulse response (IIR) filter, whose output depends on a finite number of input samples and a finite number of previous filter outputs. Due to the feedback paths, IIR filters are less numerically stable than their FIR counterparts  but provWe follow the approach by Risojević et al. . Using mThe magnitude response of the filter with transfer Function  slightlyThe digital filter defined by  will be As can be seen from , the filThe proposed filter can also be represented by matrices of its coefficents as:Q denotes the number of bits used to represent the decimal part of the filter coefficients.We tackle this problem in Q are depicted in The magnitude responses of the A-weighting filter for different values of In digital filters, the multipliers represent indispensable components that have a strong influence on their area, delay, and energy. If we employ approximate multiplier in digital filters, we can significantly improve energy consumption and area usage. Low energy consumption is a desired property as A-weighting filters are often employed as a part of battery-powered devices. However, approximate multiplication can significantly influence the A-weighting filter’s stability and magnitude response. Hence, careful design and placement of approximate multipliers are required. This section first presents an exact multiplier whose design leverages the coefficient’s quantization and then proposes an approximate multiplier, which we obtain by simplifying the exact multiplier.n-bit integers, i.e., a multiplicand X and multiplier Y in two’s complement:X and Y, respectively. In the radix-4 Booth encoding, the multiplier Y is divided into overlapping groups of three bits:A radix-4 Booth multiplier  consistsY, we can write the product j-th partial product generated from Taking into account the radix-4 enconding of n-bit multiplier. In our case, the filter coefficients of the A-weighting filter are represented with 11-bit integers. If we observe filter coefficients as Y input, the resulting radix-4 Booth multiplier generates six partial products, as shown in The previous discussion deals with the general case of an ace tree  to reducace tree .In order to reduce the number of partial products, we propose a slightly modified radix-4 encoding. The main idea behind the proposed encoding is to shift the position of group encodings one place to left, as illustrated in n-bit binary number is equal to:Now, the encoded value, In the case of an 11-bit number, the encoded value By setting Hence, the idea is to use the encoding from  and 19)19) to enIn such a way, we can decrease the number of partial products by one for binary numbers with odd number of bits.Y as followsTo avoid costly subtraction, which leads to a more complex circuitry, we propose to neglect the term Y is an odd number.or. From , we can j-th partial product generated from With the proposed approximate odd radix-4 encoding, we can calculate the product M bits of multiplier Y. The proposed omission also decreases the number of partial products, leading to even more hardware and energy-efficient design. For example, if M carefully in each first-order section.To further improve the proposed multiplier design in terms of area, delay, and energy consumption, we propose the omission of the last In this subsection, we present the error analysis of the approximate odd radix-4 (AO-RAD4) multiplier presented in the previous subsection. We analyze the mean relative error (MRE) and the relative error distribution for error assessment. MRE is obtained as an average relative error for all sets of inputs and all possible combinations for a Y. The mean relative error (MRE) is calculated as follows:The calculation of relative error for AO-RAD4 is as follows. Considering  and 23)23), the nd as in . Hence, M. The error distribution  when the parameter M increases from 3 to 4.ribution , right sIn this section, we assess the influence of the placement of approximate multipliers inside the digital A-weighting filter and the influence of the zero-pole pairing and ordering of FOS within the digital filter.Employment of approximate multiplication in the A-weighting filter requires careful placement of approximate multipliers across the FOS cascade. The simple substitution of exact multipliers with approximate ones can lead to violation of the filter’s requirements or even make the system unstable.N represents number of frequency points. The CSF ranges from 0 to 1.To determine the optimal placement of the AO-RAD4 approximate multipliers within the digital A-weighting filter, we evaluated the magnitude response of the digital A-weighting filter in the presence of approximate multiplication. For every coefficient, we replaced the exact radix-4 multiplier with different instances of AO-RAD4 multiplier while keeping other multipliers exact. Then, we checked whether the proposed digital filter’s magnitude response satisfies the criteria for the A-weighting filter. Moreover, we quantitatively assessed the similarity between magnitude responses of the proposed and the reference A-weighting filter, given by  using thM when AO-RAD4 multiplier is applied to different coefficients (factors). The combinations under which examined A-weighting filter satisfies tolerance limits for the frequency response are marked in green; otherwise, they are marked in red. As expected, the multiplications with coefficients in the FOS whose poles and zeros are further from the unit circle, are more tolerant to approximation errors and can have larger M. Now, the multiplication with the coefficients from ))z-plane.e  and mean absolute error of sound pressure level (SPL). Secondly, we have used Verilog to implement the filters and synthesize them to 45 nm Nangate Open Cell Library. The resulting values of the area, delay, and power performance are reported. Finally, we have implemented the filter in Zynq-7000 SoC on the ZYBO Z7 FPGA development board to verify the filter’s operation in a real environment.In this section, we present the MATLAB simulations of the proposed and reference A-weighting filters to observe the influence of approximate multiplications on the frequency response of the filter. We observe how much the frequency response of the proposed filter deviates from the exact frequency response given in the standard.To quantitatively assess the two magnitude responses, we used the CSF measure. To assess the proposed A-weighting digital filter’s performance with approximate multipliers, we used the DEMAND collection of acoustic noise in diverse environments ,44. For N is the number of samples in each signal. It can be observed from s represents the standard deviation of observed samples, and n represents the number of samples. We have obtained 95% CI of We have calculated two sound pressure levels for each recording: one with the proposed and one with the reference A-weighting filter. The loudness was calculated using the “fast” response (window size of 250 ms). The mean error . We compare the synthesis results of two digital A-weighting filters: the proposed digital filter with AO-RAD4 multipliers as in As can be observed from n bits of multiplicand X, and n denotes the bit width of the multiplicand, q quantization factor, and M represents the truncation parameter of approximate odd radix-4 Booth multiplier. In the proposed filter, we chose The superior hardware performance of the proposed approximate filter originates from the usage of the approximate multipliers. The proposed approximate filter and the reference filter have the same FOS structure and the same number of arithmetic operations. Still, the former employs the approximate AO-RAD4 multipliers, and the latter employs the exact radix-4 multipliers. In this way, we achieved fair comparison and eliminated the influence of the filter structure on the synthesis results. For the exact radix-4 multiplier, the complexity of the product generation stage equals To compare the Verilog model and MATLAB model outputs, we conducted the verification through FPGA prototyping. We deployed the proposed filter to the Zync 7000 SoC on the ZYBO Z7 FPGA development board. For the test inputs, we used impulse sequence and Gaussian white noise (AWGN). Employment of approximate multipliers in the A-weighting IIR filter offers remarkable savings in energy consumption and area utilization, and it has a negligible impact on its accuracy. As the approximate and the reference filter have the same structure, and the same number of first-order sections, the low area utilization and low energy consumption in the approximate filter comes solely from the employment of the approximate multipliers. The smaller number of partial products in the proposed approximate multiplier leads to a smaller circuit. Hence, the overall area and power consumption of the proposed filter have been reduced. However, careful placement of approximate multipliers in the A-weighting filter is required to meet the A-weighting filter’s accuracy, stability, and frequency response. As the criteria for placement of the approximate multipliers, we selected the similarity between magnitude responses of the proposed filter and reference filter. In other words, the optimal choice and placement of the approximate multipliers in the A-weighting filter give the magnitude response, which is almost identical to the magnitude response of the referenced A-weighting filter and satisfies the IEC 61672-1 requirements. Hence, there is an insignificant difference between signals filtered with the proposed and reference filters.As with every approximation scheme, the one proposed here also has shortcomings and limitations. The proposed approximation scheme applies only to the IIR filters that can be implemented through decomposition on the first-order sections (FOS). We selected the first-order sections as a filter building block because they have a linear relationship between coefficients and poles of a transfer function. On the other hand, we can decompose on FOS only the IIR filters with real poles or near-real poles. Besides, this study solely concentrated on deploying approximate multipliers, and the design of adders was unaltered. To further improve the proposed filters’ power consumption, we need to consider the adders’ design. To summarize, In this paper we proposed an energy-efficient A-weighting IIR digital filter that uses approximate multiplications and coefficient quantization. We have thoroughly assessed the impacts of quantization, pole-zero pairings, the positions of the first-order sections in the filter’s cascade, and the placement of AO-RAD4 approximate multipliers in the filter’s cascade on its performance. The proposed A-weighting IIR digital filter has an almost identical frequency response to the filter with exact multipliers while consuming around 70% less energy. Experiments on acoustic noise suggest that the proposed digital A-weighting filter can be deployed in environmental noise measurement applications without any notable performance degradation. In future work, we will tackle the challenges of employing approximate arithmetic in second-order sections and extending the proposed approach to general digital IIR filter design. Further research will concentrate on the employment of error correction circuits and lowering the error caused by truncation in fixed-point arithmetic.


Ripk1K376R/K376R mice, Ripk1K115R/K115R mice reached adulthood and showed slightly higher responsiveness to TNF-induced death. Cell death observed in Ripk1K376R/K376R embryos relied on RIPK1 kinase activity as administration of RIPK1 inhibitor GNE684 to pregnant heterozygous mice effectively blocked cell death and prolonged survival. Embryonic lethality of Ripk1K376R/K376R mice was prevented by the loss of TNFR1, or by simultaneous deletion of caspase-8 and RIPK3. Interestingly, elimination of the wild-type allele from adult Ripk1K376R/cko mice was tolerated. However, adult Ripk1K376R/cko mice were exquisitely sensitive to TNF-induced hypothermia and associated lethality. Absence of the K376 ubiquitination site diminished K11-linked, K63-linked, and linear ubiquitination of RIPK1, and promoted the assembly of death-inducing cellular complexes, suggesting that multiple ubiquitin linkages contribute to the stability of the RIPK1 signaling complex that stimulates NF-κB and MAPK activation. In contrast, mutating K115 did not affect RIPK1 ubiquitination or TNF stimulated NF-κB and MAPK signaling. Overall, our data indicate that selective impairment of RIPK1 ubiquitination can lower the threshold for RIPK1 activation by TNF resulting in cell death and embryonic lethality.Receptor-interacting protein 1  is a key regulator of multiple signaling pathways that mediate inflammatory responses and cell death. TNF-TNFR1 triggered signaling complex formation, subsequent NF-κB and MAPK activation and induction of cell death involve RIPK1 ubiquitination at several lysine residues including Lys376 and Lys115. Here we show that mutating the ubiquitination site K376 of RIPK1 (K376R) in mice activates cell death resulting in embryonic lethality. In contrast to  RIPK1  plays a central role in mediating signaling by TNF (Tumor necrosis factor) . BesidesTNFR1 (TNF receptor 1) trimerization induced by TNF binding results in recruitment of TRAF2 (TNF receptor-associated factor 2), TRADD (TNF receptor type 1 associated death domain protein), RIPK1 and c-IAP1 and 2 (cellular inhibitor of apoptosis 1 and 2). The E3 ligases c-IAP1/2 then ubiquitinate several proteins in the complex, including themselves and RIPK1, with K11-, K48- and K63-linked chains –21. K63-Persistent pathway activation and deubiquitination of RIPK1 can induce complex II formation. Complex II is a cytosolic complex consisting of caspase-8, FADD (Fas-associated protein with death domain), FLIP (FLICE inhibitory protein) and RIPK1 , 26. ThiRIPK1 has been implicated in numerous inflammatory and neurodegenerative pathologies in animal disease models, and by demonstration of RIPK1 pathway activation in patients , 32. MulWhile it is clear that the kinase activity of RIPK1 is dispensable for organismal homeostasis or reproduction, the physiological importance of RIPK1 ubiquitination is less clear. To assess the biological relevance of pro-survival and pro-cell death ubiquitination of RIPK1, we generated knock-in mice where K376 or K115 was mutated to arginine. RIPK1(K376R) reduced K11-linked, K63-linked, and linear RIPK1 ubiquitination, and promoted the assembly of death-inducing cellular complexes. Apoptosis in embryos caused lethality and was dependent on the catalytic activity of RIPK1, TNFR1, and caspase-8/RIPK3. RIPK1(K115R) was not lethal, but moderately enhanced responsiveness to TNF-induced death. Together, our data suggest that selective impairment of RIPK1 ubiquitination promotes activation of RIPK1, cell death, and embryonic lethality.Tnfr1−/−, Casp8+/−, Ripk3/−− and Rosa26-Cre.ERT2 mice were described before  (Roche) and complete protease inhibitor cocktail [1x] (Roche). For immunoprecipitations cells were lysed as described above with the addition of 10 mM N-ethylmaleimide . Insoluble fraction was separated from the lysate by centrifugation at 20,817 xg.Western blotting antibodies against: RIPK1 , RIPK1, pRIPK1 Ser166; Thr169 , RIPK3 , pRIPK3 Thr231; Ser232 , MLKL , pMLKL , FADD , pIκBα , IκBα , p-p65 , p65 , pJNK , JNK , p-p38 , p38 , TRADD , HOIP , SHARPIN , NEMO , caspase-3 , cleaved capsase-3 , caspase-8 [1G12] , FLIP , p-ERK , ERK , c-IAP1 , pIKKα/β , IKKβ , GAPDH , HDAC2 , HSP90 . If not otherwise indicated the antibodies were diluted 1:1000 for detection.IP was performed with anti-RIPK1 antibody  or anti-TNFR1 antibody . Complexes were purified using magnetic A/G beads (Pierce) and eluted with 1x sample buffer. For cells treated with FLAG-TNF immunoprecipitation was performed with magnetic FLAG-M2 beads .2, 1 mM EGTA, 1% (w/v) Triton X-100, 10 mM N-ethylmaleimide  and Halt Protease and Phosphatase Inhibitor Cocktail (Thermo Scientific) as recently described [Ubiquitin chain-specific IPs were performed by lysing the cells in 6 M urea containing buffer (20 mM Tris–HCl (pH 7.5), 135 mM NaCl, 1.5 mM MgClescribed . Ub-IP wYolk sacs were stained as described in Newton et al. . Fixed tBMDMs were seeded at d5 on 4 chamber tissue culture treated glass slides  and treated the following day. The cells were fixed in 4% PFA for 30 min at room temperature. Permeabilized in 0.25% Triton X-100 (w/v) and blocked in 5% BSA (w/v) and 0.05% Triton X-100 (w/v). Staining was performed with p65  for 2 h at room temperature followed by labeling with donkey anti-rabbit Cy3  and 1:2000 Hoechst (H3569). The cells were mounted with ProLong Glass Antifade Mountant (P36980). Images were acquired using a LEICA SP8 inverted microscope with a 40x objective.Ppia (Ppia-Mm02342430_g1). The following assays were used: Ppia-Mm02342430_g1, Tnfaip3-Mm00437121_m1, Cxcl1-Mm04207460_m1, Cxcl2-Mm00436450_m1, Ccl2-Mm00441242_m1, Il1b-Mm00434228_m1, Tnf-Mm00443258_m1, Relb-Mm00485664_m1, Bcl3-Mm00504306_m1 .Total RNA was extracted from cells or tissues samples using the RNeasy plus mini kit following manufactures instructions. cDNA was generated using the SuperScript IV VILO Master Mix. qRT-PCR was performed with pre-spotted and costume assembled TaqMan assay plates (Thermo Fisher Scientific) and TaqMan Fast Advanced Master Mix . Analysis was performed with the QuantStudio 7 and normalized to expression of Sera of adult mice or cell supernatants were analyzed by Luminex Panel (BioRad). The following cytokines and chemokines were analyzed from cell supernatants: MIP1α , IL-6 , G-CSF .The number of independent experiments performed is indicated in the figure legends (at least two). The variance was assumed to be similar between the compared groups and that groups have normal distribution. The statistical significance was analyzed by the indicated tests. One-way ANOVA, Two-way ANOVA and Mantel–Cox (log rank) were performed using the GraphPad Prism software.Ripk1K376R/+ animals did not produce viable Ripk1K376R/K376R (hereafter termed K376R) mice  mice were born at normal Mendelian frequencies  , whereas levels of other cytokines and chemokines such as RANTES, KC, and IFNγ were not altered  Fig.  and a mo95) Fig. . K115R aed Fig. S. While Red Fig. S. Necropted Fig. S. Based oTo investigate the role of RIPK1 catalytic activity in the lethality of RIPK1 K376R embryos, we dosed pregnant females with the RIPK1 kinase inhibitor GNE684 (ref. ). PregnaTnf, Cxcl2, Cxcl1, and Cxcl2), as well as the NF-κB target genes TNFAIP3, Bcl3, and RelB were expressed at higher levels in K376R liver when compared to WT livers  derived from WT or K376R embryos with FLAG-TNF Fig. . RIPK1K. NF-κB aWT Fig. S. UbiquitWT Fig. S. AccordiWT Fig. S. TRADD rWT Fig. S. SubcellWT Fig. S. InteresWT Fig. S, top rowRipk1K376R/+ and WT MEFs  into complex I suggested that TNF-mediated cell death might be enhanced. Indeed, treatment with TNF for up to 6 h induced caspase-3 cleavage and autophosphorylation of RIPK3 in K376R MEFs, but not in WT MEFs Fig. . SignaliFs Fig. S. GNE684 Fs Fig. S and S3E.Fs Fig. S. InteresFs Fig. S. Indeed,Fs Fig. S. AccordiFs Fig. S.Ripk1K376R/+ mice were crossed with either Tnfr1−/− mice or Casp8−/−Ripk3−/− mice. Ripk1K376R/K376RTnfr1−/− mice were born at Mendelian ratios  and Rosa26-Cre.ERT2 wRipk1cko/+ (WT/-) mice neither lost weight nor showed other signs of illness . Surprisingly, there was an overall decrease in K11-linked, K63-linked, and linear ubiquitination on RIPK1(K376R) when compared with WT RIPK1 Figs.  and S6C.RIPK1 ubiquitination plays a critical role in the spatial and temporal regulation of TNF stimulated inflammatory and cell death signaling . We analGiven that lysine 376 of RIPK1 is ubiquitinated within minutes of TNF binding to TNFR1 , 13, absInterestingly, BV6 did not increase TNF-induced cell death in K376R cells, which is consistent with deletion of the RIPK1 E3 ligases c-IAP1/2 mainly impacting ubiquitination on K376 of RIPK1. Accordingly, wild type cells with K376 available for ubiquitination were sensitized to TNF-induced death by BV6. These data reiterate the importance of c-IAP1/2 mediated RIPK1 ubiquitination for TNFR1 complex stability. Recently, two other studies reported a similar phenotype of RIPK1 K376R knockin mice , 45. HowWe also characterized the role of K115 RIPK1 ubiquitination  and founSupplemental Figure LegendsSupplemental Figures


On the other hand, with the advent of the upcoming exoplanet survey missions and technological improvements, there is a need for preliminary discrimination that can prioritize potential candidates within the fast-growing list of exoplanets. Here we estimate, for the first time and using the kinetic theory of gases, a list of the possible atmospheric species that can be retained in the atmospheres of the known exoplanets. We conclude that, based on our current knowledge of the detected exoplanets, 45 of them are good candidates for habitability studies. These exoplanets could have Earth-like atmospheres and should be able to maintain stable liquid water. Our results suggest that the current definition of a habitable zone around a star should be revisited and that the capacity of the planet to host an Earth-like atmosphere to support the stability of liquid water should be added.The detection of habitable exoplanets is an exciting scientific and technical challenge. Owing to the current and most likely long-lasting impossibility of performing  Molecules transported through chondritic and nebular elements and dissolved on the early magma through accretion processes contribute to the initial formation of the planet, forming part of its core . The plaGeological processes such as volcanic eruptions lead to a secondary atmosphere . The ult2 and He from the atmosphere of the Earth and the absence of atmosphere on the Moon. Significant improvements have been made to the thermal escape problem ever since [In 1846, Waterston  later imer since –13, inclAtmospheric escape in exoplanet atmospheres has attracted much attention from the scientific community after the detection of the hydrodynamic escape of atmospheric species from the atmosphere of hot Jupiter HD209458 b . Since tThe thermal escape in atmospheres can be divided into slow thermal escape  and hydrodynamic escape. The type of thermal escape is determined by the hydrostatic or non-hydrostatic nature of the exosphere . Only a The rate of escape of atmospheric species is influenced mainly by the activity and emitted radiation of the host star, which determines the atmospheric escape regime to be either a slow thermal escape or a hydrodynamic blow-off of the upper atmosphere ,18. The The well-established Jeans escape model requires physical parameters describing the exosphere, column density and exobase temperature for calculations. The atmospheric retrievals using transit spectroscopy and photometry could constrain the brightness temperature and pressure–temperature profiles of exoplanet atmospheres. The degeneracies due to cloud/haze and reference pressure ,24 alongHere we present a new atmospheric thermal escape model for exoplanets with hydrostatic upper atmospheres. From the fundamentals of the kinetic theory of gases, we estimate the possible atmospheric constituents. The results of our model will further provide a list of terrestrial low-mass exoplanet targets for habitability studies compiled from evaluating their possible atmospheric compositions driven by thermal escape. We incorporated a conservative approach in our calculations and, based on the known physical parameters of the exoplanets, we determine the upper limit on the mass of the species that can escape from their atmospheres, and then we estimate their possible atmospheric constituents.2.Thermal escape is a function of the temperature of the exosphere and escape velocity of the planet. The vertical temperature profile of the planet, the temperature of the host star and the gravity of the planet are the three most important parameters driving thermal escape in planetary atmospheres –12. The in situ missions and well-resolved remote sensing observations using ground-based telescopes. The observations have resulted in, broadly speaking, good knowledge of the atmospheric profiles and atmospheric compositions of the Solar System planets [The Solar System planets have been well observed, probed and studied by the scientific community since the advent of the space age with multiple satellite and  planets ,26.By contrast, for exoplanets, information about their atmospheres and compositions is hard to achieve (excluding a few close-in hot Jupiters) because of technological limitations, relatively limited observations and the astronomical distances involved. The atmospheric escape process and the resulting effluent flux of atmospheric gases is a result of a combination of multiple escape processes determined by the physical and chemical properties of the planet's atmosphere. The non-thermal escape mechanisms such as photochemical escape, ion pick-up, sputtering, the polar wind, charge exchange and impact erosion should be examined on a case-by-case basis because of their dependence on atmospheric chemistry and abundances. By means of the understanding gained from the observations of non-thermal escape processes on Mars, Titan and other icy moons, one can study the non-thermal escape processes for exoplanets with prior knowledge of their atmospheric compositions and chemical interactions. Studies on non-thermal escape processes in exoplanet atmospheres are minimal owing to the dominance of hydrodynamic escape . For a dThe main objective of this paper is to develop a method for preliminary classification of the discovered exoplanets based on their ability to hold an atmosphere. This method can be applied using the values of mass, radius and equilibrium temperature that are available or deducible for most of the discovered exoplanets. The results from our model complement the existing exoplanet classifications by adding the atmospheric component by means of thermal escape analysis, i.e. the possible atmospheric compositions, especially for low-mass exoplanets. At this juncture, when the catalogue of exoplanets is increasing drastically with new space missions coming into effect, such a simple universal method can prioritize a shortlist of exoplanets for further habitability studies and observations. Therefore, we present the model using the fundamentals of the kinetic theory of gases, estimating the atmospheric compositions by determining the atmospheric species that can escape from the atmospheres of the exoplanets through thermal escape. Our model will further place constraints on the possible dominant species in the exoplanet atmospheres, limiting the atmospheric species that could shape the atmosphere.G is a universal gravitational constant (6.6743 × 10−11 m3 kg−1 s−2) and M (kg) and R (m) are the mass and radius of the planet, respectively. The values of M and R are available for the planets of our Solar System and a good number of confirmed exoplanets [m (kg) is the mass of gas, T (K) is the temperature and kb (1.380 649 × 10−23 m2 kg s−2 K−1) is Boltzmann's constant.The escape velocity of the planet is oplanets –29. The cn is the number density of the gascT (K) is the exobase temperature, H is the scale height, R is the radius of the planet and the subscript c represents the parameters at the exobase. The Jeans escape estimate of the escape flux, U) of the gas at the exobase is more than one-sixth of the Vesc [In the formalism of Jeans escape in planetary atmospheres, as a guideline, a factor of one-sixth is used conventionally to compare the Vesc ,31.2-dominant atmosphere will have cooler exospheric temperatures and H–He-dominant atmospheres have hotter exospheres [The exobase of the exoplanets is not known, and we have no knowledge of the parameters ut 255 K ,30. The ospheres . TherefoTp (K), of an exoplanet can be computed using the Stefan–Boltzmann law,Teff (K) is the effective temperature of the star, a (unitless) is the bond albedo of the exoplanet, r (m) is the radius of the star and d (m) is the semi-major axis of the exoplanet. Owing to the unavailability of the albedo of the exoplanets, the equilibrium temperature Tp (K) is calculated by assuming zero albedo (a = 0).Because of the unavailability of the required parameters at the exobase and because the thermal escape of atmospheric species is driven by their thermal velocities, the equilibrium temperature can be the final resort to estimate slow thermal escape. In this work, we use the calculated equilibrium temperature of the exoplanets as a conservative approach to estimate and analyse the escape of the atmospheric species. The equilibrium temperature, As we use −1, including CO2 as the ‘major gases’. The gases are chosen based on their significance to the atmosphere and importance in facilitating biosignature gases. These include lighter atmospheric species from H and He and constitute most of the greenhouse gases CH4, CO2 and H2O along with six biogenic elements (CNOPSH) that are the building blocks of potential biosignature gases [In this paper, we consider atmospheric species with mass less than 44 g molre gases . The bioThe escape parameter represents the relative strength of the gravitational potential with respect to the thermal velocity. Varying the escape parameter within the constrained interval (9.3–11), greater and smaller than 10 corresponds to the weaker and stronger gravitational potential, respectively. For a given planet, the results obtained with an escape parameter greater than 10 will show more atmospheric escape, and results with a lower escape parameter will show weak atmospheric escape.U and Vesc for the atmospheric species to escape the atmosphere of an exoplanet,As observed from the results for the Solar System objects, our model is applicable and provides reasonable estimates for the terrestrial exoplanets undergoing slow thermal escape. Equation (2.5) shows the factored comparison of Although only a small fraction of gas molecules that fall under the tail end of the Maxwell–Boltzmann distribution attain such high speeds, the gas can be removed slowly and consistently from the atmosphere over geological time scales.Here we compute, for the known exoplanets, the thermal velocity of the gases and compare it with the escape velocity, as shown in equation (2.5), to determine if the gases can be retained in their atmospheres. The escape of the atmospheric species and dominant isotopes is dependent on their atomic/molecular weights and thermal velocities. The speed of axial rotation of the planet also affects the speeds of gas molecules at the higher altitudes of the atmosphere . The speFor tidally locked exoplanets, the equilibrium temperature formulation does not give a complete picture as only the dayside of the exoplanet is perpetually exposed to the radiation from the host star and the heat transport mechanisms between the dayside and nightside determine the thermal contrasts. Nonetheless, some tidally locked exoplanets with synchronous rotation around the host star, which are capable of having liquid water on their surface, have been speculated to be potentially habitable ,38. With3.(a)The escape of different atmospheric species from the atmospheres is a result of multiple mechanisms involving stellar and atmospheric conditions. Although the problem is complex, the atmospheric composition can be estimated to some extent from the atmospheric thermal escape. This can be seen by applying the model to the objects of the Solar System . An exteThe significance and the rate of mass loss from a strictly thermal or non-thermal escape process from the atmospheres are subject to multiple factors, including but not limited to radiation energy, atmospheric chemistry, elemental abundances, magnetic field strength and interactions with stellar winds. In our Solar System, the atmosphere of Earth is driven by a dominant thermal escape; on Mars, non-thermal escape mechanisms are more dominant ,15. Ther2, He.H, H As seen in 4, NH3, H2O, OCH. Along with the giant planets, Earth and Venus are known to retain oxygen and methane in their atmospheres. The planets Mercury and Mars are incapable of retaining these gases in their atmospheres. The controversial detections of trace amounts of methane (CH4), reported to be observed in the Martian atmosphere with seasonal variation, are attributed to surface or subsurface sources [4, which is the well-known dominant species in Titan's atmosphere, can escape the atmosphere. CH4 is known to escape Titan's atmosphere through various mechanisms, including hydrodynamic escape, ion pick-up, sputtering and dissociation [ sources ,42. Figuociation ,44.4 escapes from Titan's atmosphere, there is a hypothesized significant source of CH4 due to condensation and continuous supply from subsurface clathrates [4 found in its atmosphere. Similarly, Europa has been observed to have CH4 abundances attributed to the clathrates and condensing temperature [4 ice on its surface [4 dominant [Nevertheless, although CHathrates  that maiperature . Pluto,  surface . Jeans edominant . Venus adominant .2N. While the early evolution of Titan's atmosphere is still debated to this day, the accretion of NH3 in its early atmosphere was considered the primary source of N2 through photolysis [2 observed in its present atmosphere. N2 escape from Titan's atmosphere is an existing process as a result of various mechanisms and has been observed (as well as CH4 escape) by Cassini in Titan's corona [2, in its atmosphere, leading to a tenuous atmosphere. By contrast, previous work simulating aqueous chemistry in the endogenic water–rock interactions indicates the possibility of compounds rich in nitrogen, carbon and hydrogen [2-dominant atmosphere [otolysis , and theotolysis . Continus corona . Becausehydrogen . Europa,hydrogen . Pluto amosphere  and a su2CO. Carbon dioxide is a significant greenhouse gas for the Solar System planets along with H2O and CH4. The atmospheres of the planets Venus and Mars are CO2 dominant, and Earth also has significant concentrations of CO2. Gases that are lighter than CO2 escape from the atmospheres of Mercury, Europa and Pluto, as shown in 4 on Titan and condensed CH4, NH3 and H2O ice on Europa, Pluto and Triton [One of the main limitations of the kinetic theory of gases used in our model is the phase changes of the gas species determined by temperature and partial pressure, but the model still provides (as seen in d Triton –48 indic(b)The constituents of the atmosphere and ability to retain them are of vital importance to the habitability of exoplanets ,54. An e2, N2 and H2O condense are highlighted in the shaded regions. The giant exoplanets orbiting very close to the host star with very short periods (hot Jupiters) have temperatures higher than approximately 1000 K [Tp > 1000 K is populated with very hot, giant exoplanets and close-in exoplanets like Mercury. The exoplanets with Tp < 180 K would have H2O in the solid or gaseous state depending on the surface temperature and atmospheric pressure. Similarly, the exoplanets with Tp < 14 K and Tp < 63 K would have H2 and N2 in either the solid or gas phase. The results are discussed in the sections below.In y 1000 K . In figuWe have used our model to analyse 3705 exoplanets for which data required for the calculations are available (as of June 2019). We present our results using the mass-based exoplanet classification .(c)Our model, although it considers only the thermal escape of atmospheric species from atmospheres, serves the purpose of providing a preliminary classification of all exoplanets as the considered escape mechanism is prevalent for all types of exoplanets irrespective of their size.a that the exoplanets with atmospheric detections and equilibrium temperatures less than 500 K are ice/gas giants and TRAPPIST-1 exoplanets. The model concludes that the cold gas giants can trap all gases, including hydrogen, and correlates with the reported H2, CH4, H2O, K, CO and N detections in their atmospheres. The TRAPPIST-1 system is of major significance as four of the seven exoplanets are orbiting in the habitable zone (HZ) of the star and are expected to have bulk compositions in a combination of rocky and water-enriched material [figure 4a indicate that the TRAPPIST-1 exoplanets are capable of retaining H2O in the atmosphere, concurring with the expected (undetected to date) presence of water on the TRAPPIST-1 exoplanets [Here we compare our results with the atmospheric species detections recorded to date in exoplanet atmospheres. figure 4material . The resoplanets ,56.Figub shows the exoplanets which are predominantly hot Jupiters and close-in exoplanets. The hot Jupiter exoplanets, similar to HD 209458 b, HD 189733 b, WASP 12 b and GJ 436 b, being formed close to their parent star, have high temperatures and experience hydrodynamic blow-off of the atmosphere [figure 4b we estimate that all atmospheric species heavier than He can be retained in the atmosphere and that these exoplanets are capable of retaining H2O in their atmosphere; detection of both He and H2O has been reported [Figure 4mosphere –61. For reported ,63. The reported .For the exoplanets undergoing hydrodynamic escape, the estimates from our model do not concur with the detections of heavier atmospheric species in the extended atmospheres. The estimates of atmospheric species that can be retained in the atmosphere for exoplanets which do not experience hydrodynamic flow concur with the reported detections; this is demonstrated in 2 in conjunction with exoplanet masses -dominant atmospheres while also showing the distribution of Jupiter, Neptune or super-Earth-sized exoplanets across the diverse possibility of atmospheres.We group the results for exoplanets into two classes based on their capability to retain atmospheric species lighter than CO figures  and 6. T(d)e), Neptunian (10 Me < M < 50 Me) and super-Earth (2 Me < M < 10 Me) exoplanets along with two Earth-like (M < 2 Me) exoplanets. Because of their strong gravitational potential, they are capable of trapping in their atmosphere not only species with high mass but also the lightest atmospheric species such as H and He.Tp < 14 K and 14 K < Tp < 63 K, are too cold to have any gaseous species except for H and He. The formation of giant exoplanets following core accretion leading to runaway gas accretion [in situ or have experienced an outward migration [In igration .The hot Jupiter exoplanets are considered to be migrated inward and supposedly experience hydrodynamic blow-off of the atmosphere, resulting in mass loss of heavier gases such as Na and K from the atmosphere in the process . Hot Jup2 can escape from the exoplanets Kepler-186 f and TRAPPIST-1 g a shows the one-tenth escape velocity versus the equilibrium temperature along with the velocity lines of atmospheric species and figure 7b shows the distance of the exoplanet from the parent star and the temperature of the parent star. The exoplanets in Most of the atmospheric species escape from the atmospheres of exoplanets with low gravitational potential and high temperatures, as observed in our Solar System with Mercury. Figure 7(f)The HZ is defined as the region around a star where an exoplanet can have liquid water on its surface. The boundaries of the HZ around a star are estimated by considering a cloud-free, one-dimensional climate model and imposing moist-greenhouse and greenhouse limits . The habIn this paper, we introduce the following criteria to consider an exoplanet as potentially habitable: (i) ability to host an Earth-like atmosphere and (ii) have equilibrium temperatures  between 260 K and 320 K, i.e. able to host liquid water. The conservative definition of habitability indicates that an Earth-like atmosphere would have the highest probability of habitability.The zero-albedo assumption incorporated in our model results in a higher equilibrium temperature of the exoplanets. The atmospheric greenhouse effect is responsible for higher surface temperatures than the equilibrium temperature  of a planet. The extent of the feedback is strongly dependent on the type and concentrations of greenhouse gases in the atmosphere, along with several other atmospheric feedbacks . Nonethe4/H2O/N2/O2/CO2 as the dominant atmospheric species. This list of potentially habitable exoplanets includes exoplanets with masses ranging from approximately 25 Me (HD 147379 b) to approximately 0.4 Me (TRAPPIST-1 d).We find, based on our calculations described above, that 45 known exoplanets satisfy these criteria. They are shown in The most recent available listing of 55 potentially habitable exoplanets is presented in the habitable exoplanets catalogue  see ele have an On the other hand, we have found 28 additional planets, not listed in the habitable exoplanets catalogue , that ha4.With the advent of new space missions to study and characterize the exoplanets and the increasing rate of discoveries of exoplanets, the significance of finding habitable exoplanets and characterizing their atmospheres is increasing. The discrimination of exoplanets based on the gas species that they can retain in their atmospheres will help to determine the most probable candidates for potential habitability, for further atmospheric composition studies and for photochemical models.Lack of data on the exoplanets regarding their exosphere, atmospheric structure and composition renders implementing the physically correct Jeans escape a near-impossible task. The lack of atmospheric temperature profiles and compositions can be partially addressed by incorporating transit spectroscopy and radiative transfer models for hot Jupiters and close-in exoplanets. The complex problem of exoplanet exospheres could not be solved for low-mass exoplanets because of their strong dependence on local conditions .We present an atmospheric model capable of estimating the plausible composition of exoplanet atmospheres using the readily available or estimable parameters and with minimal assumptions. Our results suggest that the definition of the HZ around a star should be revisited and that the capacity of the planet to host an Earth-like atmosphere to support the stability of liquid water should be added. Our model is characteristically a straightforward model to estimate plausible atmospheric compositions. In contrast to the existing atmospheric models built on the hydrodynamic escape of hot Jupiter and close-in irradiated exoplanets ,16,72–74These results could be beneficial for the detection of specific atmospheric species and for biomarker observations of many of the active and planned exoplanet characterization missions such as the Hubble Telescope , CHEOPS The relevance of our results at the present time is emphasized by the increasing number of Earth-sized exoplanets that could follow slow thermal escape. The active and upcoming missions may fall short of characterizing atmospheres of Earth-like exoplanets around Sun-like stars . The tra2O/N2/CO2 or evaporating/thin silicate atmospheres. We also propose a conservative list of 45 exoplanets with favourable conditions such as temperature and ability to retain the essential life-related gases in their atmospheres for further habitability studies. Further analysis considering the possible escape mechanisms and chemical processes such as photodissociation, sputtering, ion pick-up and suprathermal escape would decisively determine the habitability and atmospheric compositions of these exoplanets.The model can be further improved by including the actual albedo instead of assuming a zero albedo, measured temperature profiles of exoplanets and equilibrium chemistry along with estimations of elemental abundances. Albeit with limitations, the model enables us to estimate the list of atmospheric gases that the exoplanets can retain in their atmospheres and their plausible atmospheres as compared with those observed in the Solar System. Based on the atmospheres observed on the Solar System planets, we list the exoplanets as those with H/He, Hhttps://atmospheres.research.ltu.se/exoplanets_species.phpAs exoplanets are discovered continuously, we will keep an updated list of habitable exoplanet targets and possible atmospheric species in a dedicated webpage:


Fluorescence microscopy revealed that heparin and aSN1–61 co-exist in the final fibrils. We conclude that heparin can induce the fibrillation of aSN1–61, through binding to the N-terminal with an affinity that is higher in the truncated form of aSN. It does so by specifically modulating the structure of aSN via the formation of type I β-turn structures likely critical for triggering aSN fibrillation.The intrinsically disordered protein α-synuclein (aSN) is, in its fibrillated state, the main component of Lewy bodies—hallmarks of Parkinson’s disease. Additional Lewy body components include glycosaminoglycans, including heparan sulfate proteoglycans. In humans, heparan sulfate has, in an age-dependent manner, shown increased levels of sulfation. Heparin, a highly sulfated glycosaminoglycan, is a relevant mimic for mature heparan sulfate and has been shown to influence aSN fibrillation. Here, we decompose the underlying properties of the interaction between heparin and aSN and the effect of heparin on fibrillation. Via the isolation of the first 61 residues of aSN, which lacked intrinsic fibrillation propensity, fibrillation could be induced by heparin, and access to the initial steps in fibrillation was possible. Here, structural changes with shifts from disorder via type I β-turns to β-sheets were revealed, correlating with an increase in the aSN The intrinsically disordered protein (IDP) α-synuclein (aSN)  locates The 140 residues of aSN can be divided into three regions: the N-terminal region (residues 1–60), the non-amyloid-β component (NAC) region (residues 61–95) and the C-terminal region (residues 96–140)  and in vaSN has been linked to different neurodegenerative diseases referred to as synucleinopathies. In Parkinson’s disease (PD), cellular deposits found in the substantia nigra, called Lewy bodies, are rich in aSN . Here, aHeparan sulfate proteoglycans (HSPGs) have recently been shown to be present in Lewy bodies from PD patients . Proteog1–61) in isolation and showed it to be as disordered as full-length aSN. We show that heparin binds directly to the N-terminal end of aSN1–61 and does so with a higher affinity than to full-length aSN. While we did not observe fibrillation of aSN1–61 on its own, we intriguingly also observed heparin-induced fibrillation of aSN1–61 and detected heparin as a co-existing partner of the fibrils. The co-existing fibrils of aSN1–61/heparin accelerated the fibrillation of full-length aSN as well as the further fibrillation of aSN1–61. In addition, our data suggest that no individual property of heparin but rather the combined physical and chemical characteristics modulate the structure of aSN by inducing type I β-turn structures, which may be critical for triggering aSN fibrillation.In this study, we addressed the interplay between heparin and aSN. To remove complications from fibrillation, we focused on the aSN N-terminal (aSNHeparin was purchased from Iduron (HEP001). It was dissolved in 50 mM sodium phosphate, pH 7.4, with 0–500 mM NaCl and stored at 4 °C for a maximum of two days before use. Chondroitin sulfate A from bovine trachea and β-casein from bovine milk were purchased from Sigma-Aldrich .1–61 was purchased from GenScript® . BL21 (DE3) E. coli cells were heat-shock transformed with the plasmid, incubated in Super Optimal Broth medium for 1 h and plated on agar containing 1:1000 ampicillin (100 mg/mL). The plates were incubated overnight at 37 °C, and preheated Luria Bertani (LB) medium (50 mL) with 1:1000 ampicillin (100 mg/mL) was inoculated with one colony and incubated overnight at 37 °C and 200 rpm. Glycerol stocks were made from the overnight culture by mixing them 1:1 (volume) with 86% (v/v) sterile glycerol, aliquoted in 0.5 mL and stored at −80 °C. For expression, an aliquot of 2 μL of the glycerol stock, or a colony from the agar plate, was transferred to preheated LB medium with 1:1000 of ampicillin (100 mg/mL) and incubated overnight at 37 °C and 200 rpm. The LB expression cultures, each 1 L, contained 1:1000 of ampicillin (100 mg/mL) and were inoculated with 1:100 of the overnight culture and incubated at 37 °C and 200 rpm. The expression of His-SUMO-aSN1–61 was induced with 1:1000 of IPTG (1 M) at OD600 = 0.5–0.6. The cells were harvested 2 h after induction by centrifugation at 4801× g for 20 min at 4 °C. The cells were dissolved in 30 mL of buffer A  per L of expression medium. The cell pellet was stored at −20 °C until purification.A pET-11a vector with an insert for His-SUMO-aSNg for 20 min at 4 °C. The supernatant was loaded onto a 5 mL HisTrap FF column  equilibrated in buffer A with a flow of 1 mL/min. His-SUMO-aSN1–61 was eluted from the column using a step gradient with imidazole—10, 200, and 500 mM imidazole—with at flow of 2 mL/min. Fractions of 5 mL were collected and analyzed by SDS-PAGE, fractions containing His-SUMO-aSN1–61 were pooled, and 0.5–1 mL of 10 μM His-ULP1 was added (see below for production details). The solution with His-SUMO-aSN1–61 and His-ULP1 was subsequently dialyzed overnight at 4 °C in 50 mM Tris, 150 mM NaCl, 10 mM imidazole, 1 mM 2-mercaptoethanol, pH 8, in dialysis bags with a cut-off of 3.5 kDa. The dialysate was loaded onto a HisTrap FF column equilibrated in buffer A. The flow-through containing the cleaved aSN1–61 was collected in fractions of 5 mL. aSN1–61 was dialyzed into 50 mM Tris, 10 mM NaCl, pH 8.5, using a cut-off of 3.5 kDa. The dialysate was loaded onto an HiTrap FF SP 5 mL column , equilibrated with 50 mM Tris, 10 mM NaCl, pH 8.5, and aSN1–61 was eluted with a 0–100% step gradient to 0.5 M NaCl using a flow rate of 1 mL/min. aSN1–61 was collected in fractions of 0.5 mL. Afterwards were the fractions with aSN1–61 dialyzed overnight at 4 °C in a 50 mM sodium phosphate buffer, 150 mM NaCl, pH 7.4, with a Spectra-Por® Float-A-Lyzer® G2 , with a cutoff of 3.5 kDa.The resuspended cell pellet was lysed by six cycles of thawing and freezing in liquid nitrogen. The lysed cells were centrifuged at 25,515× 1–61 was determined using a Pierce™ BCA Protein Assay Kit , following the standard protocol for microplate mode. Incubation and measurements were performed using a FLUOstar OMEGA plate reader . The identity of the purified aSN1–61 was confirmed by amino acid analysis by ALPHALYSE™ .The concentration of aSN600 = 0.6. The cells were harvested after 3 h at 4801× g, and the cell pellet was resuspended and stored at −20 °C. The cells were lysed with osmotic shock, and non-thermostable proteins were removed by boiling and centrifugation. The supernatant was dialyzed overnight in 20 mM Na2HPO4, 2.5 mM EDTA at pH 6.5. The dialyzed solution was filtered through a 0.45 μm filter and loaded onto a 5 mL HiTrap Q FF column  equilibrated in 20 mM Na2HPO4, 2.5 mM EDTA at pH 6.5. aSN was eluted by a linear gradient with a final salt concentration of 0.5 M NaCl. Fractions containing aSN were pooled and loaded onto a Superdex 200 size exclusion column 120:100 , which was equilibrated in 50 mM Na2HPO4, 150 mM NaCl, pH 7.4. Fractions containing aSN were pooled at stored at −80 °C. Before the experiments, aSN was dialyzed with a cut-off of 3.5 kDa into 50 mM sodium phosphate, 150 mM NaCl, pH 7.4.The purification of full-length aSN was essentially performed as previously described  with a f6-tagged ULP1 was purified as described in Prestel et al., 2019 ..VTNV con1–61 upon heparin binding; instead we observed, for the first time, the formation of type 1 β-turn structures. We speculate that this was observed only in the presence of low ratios of heparin and only in aSN1–61, as it is otherwise a transiently formed structure that quickly develops into structures dominated by β-sheets.It is also well known that aSN can interact with membranes through the imperfect motifs, leading to formation of helical structures . This in1–61 to induce structural changes that lead to fibril formation. It has been suggested that heparin does not promote the fibrillation of aSN by interaction but rather stimulates a transition state that favors the β-sheet structure, eventually leading to fibril formation [1–61 stimulated by heparin is based on binding-induced structural changes in the N-terminal, likely through an initial stabilization of type I β-turns. In support of this notion, the β-wrap in AS69 has been shown to stabilize and induce a β-hairpin structure in aSN residues 37–54; a structure that contains a β-turn [Indeed, biphasic behavior was observed for some of the ThT profiles, which could lead to the speculation that heparin needs to interact with aSNormation . Based oa β-turn ,87 and t1–61 monomer, and an even lower one for aSN, it is likely to be enhanced in the oligomer and the fibrils through an avidity or local concentration effects, but given the need for heparin to induce the fibrils, we were not able to decipher these affinities.Heparin may also function as a scaffold and/or structural support for fibril formation. In the case of Tau, the presence of heparin induces different structural polymorphic forms, and in the corresponding cryo-EM structures, density can be observed in proximity of, for example, the outer lysines, potential interaction sites of heparin . In a stA key observation made in this work was that heparin at low concentrations bound to the N-terminal of aSN and induced type-I β-turn structures that are likely a key passageway for entering the fibrillation pathway. Thus, heparan sulfates of the cell surface HSPGs may not only internalize the fibrillar aggregates but also stabilize and/or induce the initial fibrillation-prone states . If this2+-bound state [2+-levels have been reported in patients with Alzheimer’s disease with Lewy Bodies [2+ or membrane binding, or by phosphorylation or mutations, may not change the size of each population dramatically but can have a large functional impact, including under pathophysiological conditions. Decomposing all the relevant states of aSN is therefore important for understanding its function as an IDP. The heparin bound form is one.Access to the N-terminal is easier and less sterically hindered in the truncated aSN than that in the full-length counterpart, and although the affinity of heparin for aSN was low, heparin still also promoted the fibrillation of full-length aSN. In a cellular context, increased access to the N-terminal may occur in the Cand state , and incy Bodies . Similary Bodies ,94. Thus1–61 variant, we observed direct binding of heparin to the N-terminal ~50 residues of aSN. The aSN1–61 variant did not possess intrinsic fibrillation potential, but heparin could act as a promoter for initiating fibrillation, via the induction of type-I β-turn structures in the aSN N-terminal. These structures were observed by CD spectroscopy through a distinct ellipticity profile. Heparin co-existed with aSN1–61 in the formed fibrils, likely in the form of a structural scaffold, and the co-fibrils seeded additional fibrillation even in the absence of free heparin, as well as of full-length aSN, resulting in fibrils with a potentially different morphology compared to that of fibrils formed by aSN alone. Thus, small amounts of heparin, or more likely that in the form of aged heparan sulfate with an increased level of sulfation, present in Lewy bodies of PD patients, can potentially initiate a cascade of fibrillation-relevant events.By removing the complexity arising from the process of aSN fibrillation by focusing on the aSN