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Independent estimation and verification of fossil CO2 emissions on a regional and national scale are crucial for evaluating the fossil CO2 emissions and reductions reported by countries as part of their nationally determined contributions (NDCs). Top-down methods, such as the assimilation of in situ and satellite observations of different tracers (e.g., CO2, CO, Δ14CO2, XCO2), have been increasingly used for this purpose. In this paper, we use the Lund University Modular Inversion Algorithm (LUMIA) to estimate fossil CO2 emissions and natural fluxes by simultaneously inverting in situ synthetic observations of CO2 and Δ14CO2 over Europe. We evaluate the inversion system by conducting a series of observing system simulation experiments (OSSEs). We find that in regions with a dense sampling network, such as western/central Europe, adding Δ14CO2 observations in an experiment where the prior fossil CO2 and biosphere fluxes are set to zero allows LUMIA to recover the time series of both categories. This reduces the prior-to-truth root mean square error (RMSE) from 1.26 to 0.12 TgC d−1 in fossil CO2 and from 0.97 to 0.17 TgC d−1 in biosphere fluxes, reflecting the true total CO2 budget by 91 %. In a second set of experiments using realistic prior fluxes, we find that in addition to retrieving the time series of the optimized fluxes, we are able to recover the true regional fossil CO2 budget in western/central Europe by 95 % and in Germany by 97 %. In all experiments, regions with low sampling coverage, such as southern Europe and the British Isles, show poorly resolved posterior fossil CO2 emissions. Although the posterior biosphere fluxes in these regions follow the seasonal patterns of the true fluxes, a significant bias remains, making it impossible to close the total CO2 budget. We find that the prior uncertainty of fossil CO2 emissions does not significantly impact the posterior estimates, showing similar results in regions with good sampling coverage like western/central Europe and northern Europe. Finally, having a good prior estimate of the terrestrial isotopic disequilibrium is important to avoid introducing additional noise into the posterior fossil CO2 fluxes.

Abstract Serial macromolecular crystallography has become a powerful method to reveal room temperature structures of biological macromolecules and perform time-resolved studies. ID29, a flagship beamline of the ESRF 4th generation synchrotron, is the first synchrotron beamline in the world capable of delivering high brilliance microsecond X-ray pulses at high repetition rate for the structure determination of biological macromolecules at room temperature. The cardinal combination of microsecond exposure times, innovative beam characteristics and adaptable sample environment provides high quality complete data, even from an exceptionally small amount of crystalline material, enabling what we collectively term serial microsecond crystallography (SµX). After validating the use of different sample delivery methods with various model systems, we applied SµX to an integral membrane receptor, where only a few thousands diffraction images were sufficient to obtain a fully interpretable electron density map for the antagonist istradefylline-bound A2A receptor conformation, providing access to the antagonist binding mode. SµX, as demonstrated at ID29, will quickly find its broad applicability at upcoming 4th generation synchrotron sources worldwide and opens a new frontier in time-resolved SµX.

Carbon nanotubes (CNTs) have the extraordinary potential to change our lives by improving existing products and enabling new ones. Current and future research and industrial workforce professionals are very likely to encounter some aspects of nanotechnology including CNT science and technology in their education or profession. The simple structure and interesting chemistry of CNTs make their inclusion in an undergraduate curriculum appropriate. An overview of the chemistry of CNTs is presented starting with a brief history followed by discussions on chemical structure, exceptional properties, potential applications, nature of technological challenges, and possible solutions that will expand the optimal utilization of these materials in the near future. This article is intended to be a starting point for developing a variety of CNT-based undergraduate projects. (Contains 5 tables and 10 figures.)

Real-time PCR (quantitative PCR or qPCR) has become the preferred method for validating results obtained from assays which measure gene expression profiles. The process uses reverse transcription polymerase chain reaction (RT-PCR), coupled with fluorescent chemistry, to measure variations in transcriptome levels between samples. The four most commonly used fluorescent chemistries are SYBR[R] Green dyes and TaqMan[R], Molecular Beacon or Scorpion probes. SYBR[R] Green is very simple to use and cost efficient. As SYBR[R] Green dye binds to any double-stranded DNA product, its success depends greatly on proper primer design. Many types of online primer design software are available, which can be used free of charge to design desirable SYBR[R] Green-based qPCR primers. This laboratory exercise is intended for those who have a fundamental background in PCR. It addresses the basic fluorescent chemistries of real-time PCR, the basic rules and pitfalls of primer design, and provides a step-by-step protocol for designing SYBR[R] Green-based primers with free, online software. (Contains 8 figures.)

As part of a campus-wide, externally funded project to increase performance in, enthusiasm for, and retention within STEM disciplines, we developed an interdisciplinary, team-taught first-year seminar course. The construction and delivery of this course was designed to show the relevance of selected general chemistry topics such as matter and energy to students in STEM disciplines outside of chemistry, particularly to pre-engineering students. Centered on a "science in space" theme, students in the course participated in a series of hands-on, open-ended activities adapted from the chemical education literature. Concept maps were used as assessment tools to measure improvement of cognition, critical thinking, and problem-solving skills. These instruments were also useful in evaluating the students' grasp of relevance regarding general chemistry topics. At the end of the course, participating students have shown improvement in all targeted skill areas and articulate the relevance of chemistry to engineering, physics, and other STEM disciplines. Additionally, students participating in this program have increased academic success during their first year and beyond, as measured by retention, test performance, GPA, and progression metrics. (Contains 2 tables and 5 figures.)

The review focuses on photoinduced electron transfer (PET) reactions between small molecules and various kinds of chemical and biological systems using a weak external magnetic field (MF). Laser flash photolysis is a competent tool to characterize the intermediates which are formed due to PET. A weak MF, very close to the hyperfine interaction of the system, has the potential to inhibit or enhance reaction channels for singlet and triplet states, which eventually effects the product distribution. At first, well-documented examples of PET involving small molecules like derivatives of phenazines, carbazoles and acridines with classical electron donors in varying homogeneous and heterogeneous media have been discussed and the influence of a weak MF on the dynamics of PET is highlighted. Secondly, utilization of magnetic field effect (MFE) to probe PET in protein pockets has been described. Thirdly, an extensive discussion on PET involving nucleobases, nucleosides, nucleotides and nucleic acids and subsequent MFE on such reactions has been reported. Next, MFE has been exploited to study PET involving nanomaterials. Finally, some very recent studies of MFE have been discussed. Thus, this review is an attempt to unravel various aspects of PET in a large number of systems of varying dimensions by means of several facets of MFE like B1/2 parameter, its capability to authenticate the initial spin state and distance dependence property.

The mini review focuses on the work carried out in our laboratory over the last two and a half decades to unravel various facets of photoinduced processes, viz. photoinduced electron transfer (PET), excited state proton transfer, energy transfer etc., using fluorescence spectroscopy and imaging. We have demonstrated that PET is manifested by formation of exciplex and that its parent spin state is authenticated by observing steady-state fluorescence in presence of magnetic field, which is quite a non-conventional set-up. It is observed that dielectric constant of the medium governs the magnetic field effect. We have synthesized and explored fluorophores which act as sensors for hydrogen bonds and protic media. Our group has studied the protonation equilibrium of Acridine, which is a good fluorophore in various confined media and observed the perturbation of this equilibrium in presence of DNA bases using steady-state and time-resolved fluorescence techniques. Excimer formation of 9-Aminoacridine Hydrochloride Hydrate (9AA), another strong fluorophore, has been investigated in several solvent matrices and photoinduced interactions of 9AA with amines and viologens are studied. Further, we have utilized fluorescence upconversion technique to segregate direct and diffusion-controlled electron transfer within picosecond-femtosecond time domain. Then attempts have been made to study DNA-ligand and protein-ligand interactions comprehensively, utilizing different techniques of fluorescence spectroscopy. Furthermore, we have synthesized fluorescent carbon dots and have made an endeavor to find their fruitful biological significance. We have also synthesized riboflavin (Rf)-gold nano-assemblies (RfS@AuNPs) by covalently attaching thiolated Rf to gold nanoparticles (AuNPs) and have observed that these RfS@AuNPs accumulate in the nucleus of cancer cells, leading to plasma membrane blebbing and binucleated apoptotic bodies, consistent with activation of apoptosis. Finally, some very recent examples as well as the future prospect of fluorescence spectroscopy have been discussed.

Introduction: In many tumours, Human Epidermal Growth Factor Receptor 2 (HER2) expression and HER2 amplification are studied as therapeutic and prognostic factors. The incidence of HER2/neu expression and its consequences in patients with colorectal carcinoma has shown conflicting evidence. Aim: To evaluate the utility of HER2/neu expression in colorectal carcinoma and to find any association between HER2/neu expression, histological grade, and stage of the tumour. Materials and Methods: This cross-sectional study was conducted on 50 cases of colorectal carcinoma. Patients undergoing surgery for colorectal tumours were selected over an 18-month period (January 2020 to June 2021) in a tertiary care hospital in Kolkata, West Bengal, India. Various clinical and demographic parameters were obtained from the patients, and the specimens were subjected to Immunohistochemical (IHC) staining for HER2/neu. The results were analysed using Statistical Package for the Social Sciences (SPSS) software version 25.0 (IBM, Armonk, New York, USA). Results: On HER2/neu IHC examination, 30 cases (60%) showed a 3+ score, 4 cases (8%) showed a 2+ score, 7 cases (14%) showed a 1+ score, and the remaining 9 cases (18%) showed a score of 0. HER2/neu expression was found in 30 cases (60%) of colorectal carcinoma. HER2/neu expression showed a significant association with the histological grade of the tumour (p-value=0.020). HER2/neu expression also showed a significant association (p-value

Synthetic carbon-based compounds are a prevalent wastewater contaminant that can adversely impact water resources due to their potential carcinogenic and toxic effects on aquatic biota and human health. This research investigates the versatility of graphene oxide (GO) as an alternative to commonly used adsorbents (zeolite NaY (NaY) and granular activated carbon (GAC)) for removal of synthetic cationic dyes. Rhodamine B (RhB) and methylene blue (MB), were selected as the target contaminants to represent cationic synthetic dyes with differing molecular sizes and structural compositions. Batch experiments using GO, NaY, and GAC as adsorbents were used to assess both physicochemical interactions between adsorbent surfaces and contaminants, and removal efficiency. GO demonstrated the highest removal efficiency for both target contaminants—at 99% and 86%, respectively—while the lowest removal efficiency was observed for NaY. Langmuir, Freundlich, Temkin, and BET isotherm models were used to describe the adsorption isotherms. Overall, GO demonstrated a more robust and higher removal efficiency of cationic dyes compared with GAC and NaY, indicating the potential of graphene oxide for the removal of complex structured organic contaminants in wastewater treatment.

Supramolecular chemistry is a relatively new field of study that utilizes conventional chemical knowledge to produce new edges of smart materials. One such material use of supramolecular chemistry is the development of sensing platforms. Biologically relevant molecules need frequent assessment both qualitatively and quantitatively to explore several biological processes. In this review, we have discussed supramolecular sensing techniques with key examples of sensing several kinds of bio-analytes and tried to cast light on how molecular design can help in making smart materials. Moreover, how these smart materials have been finally used as sensing platforms has been discussed as well. Several useful spectroscopic, microscopic, visible, and electronic outcomes of sensor materials have been discussed, with a special emphasis on device-based applications. This kind of comprehensive discussion is necessary to widen the scope of sensing technology.

Aluminium is preferred over iron for various uses as it is lighter, rust-proof and has an exceptional strength-to-weight ratio. Aluminium is more reactive than iron because of its higher standard reduction potential but it forms a self-protective layer of Al2O3 due to its higher reducing potential. Still, aluminium is corroded in acidic and alkaline media. The present research paper reports the corrosion behaviour of aluminium in 0.1 M NaOH solution with Alizarin Red S (ARS) or Xylenol Orange (XO) as an inhibitor. Corrosion potential, Corrosion current, Tafel slopes (βc) and (βa) for aluminium corrosion have been potentiodynamically investigated. The weight loss method has also been used to calculate the inhibition efficiencies of these additives. The corroded surfaces have been characterized by SEM images. It is found that corrosion potential values change significantly towards the anodic direction in the presence of ARS but they are sifted towards a cathodic direction at a high concentration of XO. While ARS shows a corrosion inhibition effect, XO shows a reverse effect. The inhibition efficiency values of ARS and XO calculated from corrosion current in potentiodynamic polarization studies tally with those calculated from weight loss studies. Studies on a laboratory model of aluminium-air batteries in 0.1 M NaOH containing these organic additives show that the discharge curve of the cell is improved in the presence of ARS and XO in combination. The results are explained in terms of the formation of well-known Al+3.3ARS− and Al+3-XO6− complexes. At room temperature, 1.0 × 10−3 M solution of ARS is found effective in inhibiting the corrosion of aluminium while the same concentration of XO is acting as a corrosion accelerator. This interesting study can be very vital in the field of corrosion science.

We have constructed an atmospheric inversion framework based on TM5-4DVAR to jointly assimilate measurements of methane and δ13C of methane in order to estimate source-specific methane emissions. Here we present global emission estimates from this framework for the period 1999–2016. We assimilate a newly constructed, multi-agency database of CH4 and δ13C measurements. We find that traditional CH4-only atmospheric inversions are unlikely to estimate emissions consistent with atmospheric δ13C data, and assimilating δ13C data is necessary to derive emissions consistent with both measurements. Our framework attributes ca. 85 % of the post-2007 growth in atmospheric methane to microbial sources, with about half of that coming from the tropics between 23.5∘ N and 23.5∘ S. This contradicts the attribution of the recent growth in the methane budget of the Global Carbon Project (GCP). We find that the GCP attribution is only consistent with our top-down estimate in the absence of δ13C data. We find that at global and continental scales, δ13C data can separate microbial from fossil methane emissions much better than CH4 data alone, and at smaller scales this ability is limited by the current δ13C measurement coverage. Finally, we find that the largest uncertainty in using δ13C data to separate different methane source types comes from our knowledge of atmospheric chemistry, specifically the distribution of tropospheric chlorine and the isotopic discrimination of the methane sink.

Despite the consensus on the overall downward trend in Amazon forest loss in the previous decade, estimates of yearly carbon emissions from deforestation still vary widely. Estimated carbon emissions are currently often based on data from local logging activity reports, changes in remotely sensed biomass, and remote detection of fire hotspots and burned area. Here, we use 16 years of satellite-derived carbon monoxide (CO) columns to constrain fire CO emissions from the Amazon Basin between 2003 and 2018. Through data assimilation, we produce 3 d average maps of fire CO emissions over the Amazon, which we verified to be consistent with a long-term monitoring programme of aircraft CO profiles over five sites in the Amazon. Our new product independently confirms a long-term decrease of 54 % in deforestation-related CO emissions over the study period. Interannual variability is large, with known anomalously dry years showing a more than 4-fold increase in basin-wide fire emissions relative to wet years. At the level of individual Brazilian states, we find that both soil moisture anomalies and human ignitions determine fire activity, suggesting that future carbon release from fires depends on drought intensity as much as on continued forest protection. Our study shows that the atmospheric composition perspective on deforestation is a valuable additional monitoring instrument that complements existing bottom-up and remote sensing methods for land-use change. Extension of such a perspective to an operational framework is timely considering the observed increased fire intensity in the Amazon Basin between 2019 and 2021.

Abstract Insertion‐type layered Na2Ti3O7 has attracted the attention of the researchers and is considered to be one of the promising low‐voltage anode materiasl for sodium‐ion batteries. In spite of its fascinating electrochemical properties, the low electronic conductivity and structural instability of Na2Ti3O7 are major drawbacks that restrict its practical application. Surface modification with pyrolytic carbon is one of the effective ways to reduce irreversible capacity loss caused by electrolytic degradation. In this work, attempts have been made to investigate the effects of different carbon coating approaches on the electrochemical properties of sol‐gel‐synthesized Na2Ti3O7 microrods. The as‐synthesized Na2Ti3O7 rods are coated with a uniform carbon layer both by in‐situ and ex‐situ methods using citric acid and polyvinyl alcohol as carbon source, respectively. Ex‐situ carbon‐coated Na2Ti3O7 (Na2Ti3O7@C), due to better coating uniformity and higher graphitized carbon percentage, shows enhanced cyclability and rate performance compared to bare material and in‐situ carbon composite (Na2Ti3O7/C). Following the ex‐situ carbonization method using PVA as carbon source, it is found that increase of carbon content from 5wt% to 10wt% significantly improves its electrochemical properties. However, further increase in PVA amount has adverse effect on the cycling as well as rate performance of Na2Ti3O7@C. Surface modified Na2Ti3O7@C with optimum carbon content (10wt% C) shows improved cycling capacity (capacity retention ∼74.75% after100 cycle) and rate performance (∼67 mAhg‐1 at 1.5 Ag‐1). Both excess and inadequate carbon content have detrimental effect on the electrochemical properties of Na2Ti3O7 anode.

The Orbiting Carbon Observatory 2 (OCO-2) satellite has been providing information to estimate carbon dioxide (CO2) fluxes at global and regional scales since 2014 through the combination of CO2 retrievals with top–down atmospheric inversion methods. Column average CO2 dry-air mole fraction retrievals have been constantly improved. A bias correction has been applied in the OCO-2 version 9 retrievals compared to the previous OCO-2 version 7r improving data accuracy and coverage. We study an ensemble of 10 atmospheric inversions all characterized by different transport models, data assimilation algorithms, and prior fluxes using first OCO-2 v7 in 2015–2016 and then OCO-2 version 9 land observations for the longer period 2015–2018. Inversions assimilating in situ (IS) measurements have also been used to provide a baseline against which the satellite-driven results are compared. The time series at different scales (going from global to regional scales) of the models emissions are analyzed and compared to each experiment using either OCO-2 or IS data. We then evaluate the inversion ensemble based on the dataset from the Total Carbon Column Observing Network (TCCON), aircraft, and in situ observations, all independent from assimilated data. While we find a similar constraint of global total carbon emissions between the ensemble spread using IS and both OCO-2 retrievals, differences between the two retrieval versions appear over regional scales and particularly in tropical Africa. A difference in the carbon budget between v7 and v9 is found over this region, which seems to show the impact of corrections applied in retrievals. However, the lack of data in the tropics limits our conclusions, and the estimation of carbon emissions over tropical Africa require further analysis.

Atomically precise gold nanoclusters hold promise as non-linear optical probes for biological imaging. Here functionalized luminescent gold nanoclusters bind free carbonyls via oxime bond formation, allowing detection of carbonylated proteins via gel electrophoresis and fluorescence imaging.

The transition between gapped (semiconducting) and gapless (metallic) phases and tunability of bandgap in materials is a very lucrative yet considerably challenging goal for new-age device preparation. For bulk materials and for two-dimensional layered systems, this is a rapidly expanding field. We theoretically propose a one-dimensional pure carbon material with a tunable bandgap. We find that two parallel coupled polyyne chains show metallic behaviour with bands crossing on the Fermi level, unlike the single semiconducting chain. The number of nodal points (two) is robust under transverse and longitudinal strain, indicating the symmetry-protected nature of the metallic phase. Sliding one chain with respect to the other breaks reflection symmetry and a clear bandgap opens up at the nodes, leading to a gapped phase. By varying the slide parameter, the bandgap can be tuned efficiently. This work initiates and indicates possible topological phases of real one-dimensional materials without the involvement of edge modes.

In the 21st century, melanoma and non-melanoma skin cancers have become an epidemic outbreak worldwide. Therefore, the exploration of all potential preventative and therapeutic measures based on either physical or bio-chemical mechanisms is essential via understanding precise pathophysiological pathways (Mitogen-activated protein kinase, Phosphatidylinositol 3-kinase Pathway, and Notch signaling pathway) and other aspects of such skin malignancies. Nano-gel, a three-dimensional polymeric cross-linked porous hydrogel having a diameter of 20–200 nm, possesses dual properties of both hydrogel and nanoparticle. The capacity of high drug entrapment efficiency with greater thermodynamic stability, remarkable solubilization potential, and swelling behavior of nano-gel becomes a promising candidate as a targeted drug delivery system in the treatment of skin cancer. Nano-gel can be either synthetically or architectonically modified for responding to either internal or external stimuli, including radiation, ultrasound, enzyme, magnetic, pH, temperature, and oxidation-reduction to achieve controlled release of pharmaceuticals and several bio-active molecules such as proteins, peptides, genes via amplifying drug aggregation in the active targeted tissue and reducing adverse pharmacological effects. Several drugs, such as anti-neoplastic biomolecules having short biological half-lives and prompt enzyme degradability capacity, must be appropriate for administration employing either chemically bridged or physically constructed nano-gel frameworks. The comprehensive review summarizes the advancement in the preparation and characterization methods of targeted nano-gel with enhanced pharmacological potential and preserved intracellular safety limits for the mitigation of skin malignancies with a special emphasize on skin cancer inducing pathophysiological pathways and prospective research opportunities for skin malignancy targeted nano-gels.

Exosomes, whose mean diameter ranges from 20 nm to 200 nm, are cell-secreted vesicles and are abundant in most biological fluids, such as blood, urine, tears, sweat, breast milk, etc. Exosomal size variations and their composition can be attributed to several factors, such as age, gender and disease conditions of the individual. Existing techniques, such as ultracentrifugation and density gradient ultracentrifugation, for exosome isolation are instrument-dependent, time-consuming and lack specificity. In the present work, a gold-nanoparticle (GNP)-coated silicon (Si) wafer, functionalized with polyethylene glycol (PEG) was used for conjugation with anti-CD63 antibody via EDC NHS chemistry and incubated with serum to immobilize the exosomes on the Si surface. The surface-immobilized exosomes were eluted and quantified by a nanoparticle tracking analyzer (NTA). It was observed that an increase in GNP density on the Si wafer increases the size range and total number of exosomes that are being isolated. Western blotting performed for proteins such as HSP 70 and calnexin confirmed the immobilization and elution of exosomes. The proposed technique can be used as an alternative to existing techniques, as it has several benefits such as reusability of the Si surface for several isolations, minimal instrumental requirement, isolation of exosomes in two hours and compatibility with the microfluidic platform, making the technique suitable for real-time application. The proposed method could be useful in isolating a specific subrange of exosomes by altering the size of the GNP used for coating the Si wafer.

Biodiesel is a promising energy substitute of fossil fuels since it is produced from renewable and biodegradable sources. In the present work, reactive distillation (RD) process is designed and simulated using Aspen Plus process simulator to produce biodiesel of high purity through esterification reaction. The simultaneous reaction and separation in same unit enhances the biodiesel yield and composition in RD process. Two flowsheets are proposed in present work. In the first flowsheet, the unreacted methanol is recycled back to reactive distillation column. Biodiesel with 99.5 mol% purity is obtained in product stream while the byproduct stream comprises 95.2 mol% water, which has to be treated further. In the second flowsheet, a part of methanol recycle is split and purged. In this case, the biodiesel composition in product stream is 99.7 mol% whereas water composition is 99.9 mol% in byproduct stream, which can be reused for other process without treatment.

The Orbiting Carbon Observatory-2 has been on orbit since 2014, and its global coverage holds the potential to reveal new information about the carbon cycle through the use of top-down atmospheric inversion methods combined with column average CO2 retrievals. We employ a large ensemble of atmospheric inversions utilizing different transport models, data assimilation techniques, and prior flux distributions in order to quantify the satellite-informed fluxes from OCO-2 Version 7r land observations and their uncertainties at continental scales. Additionally, we use in situ measurements to provide a baseline against which to compare the satellite-constrained results. We find that within the ensemble spread, in situ observations, and satellite retrievals constrain a similar global total carbon sink of 3.7±0.5 PgC yr−1, and 1.5±0.6 PgC yr−1 for global land, for the 2015–2016 annual mean. This agreement breaks down in smaller regions, and we discuss the differences between the experiments. Of particular interest is the difference between the different assimilation constraints in the tropics, with the largest differences occurring in tropical Africa, which could be an indication of the global perturbation from the 2015–2016 El Niño. Evaluation of posterior concentrations using TCCON and aircraft observations gives some limited insight into the quality of the different assimilation constraints, but the lack of such data in the tropics inhibits our ability to make strong conclusions there.

Exosomes are cell-secreted vesicles secreted by a majority of cells and, hence, populating most of the biological fluids, namely blood, tears, sweat, swab, urine, breast milk, etc. They vary vastly in size and density and are influenced by age, gender and diseases. The composition of exosomes includes lipids, DNA, proteins, and coding and noncoding RNA. There is a significant interest in selectively isolating small exosomes (≤50 nm) from human serum to investigate their role in different diseases and regeneration. However, current techniques for small exosome isolation/purification are time-consuming and highly instrument-dependent, with limited specificity and recovery. Thus, rapid and efficient methods to isolate them from bio fluids are strongly needed for both basic research and clinical applications. In the present work, we explored the application of a bench-top centrifuge for isolating mostly the small exosomes (≤50 nm). This can be achieved at low g-force by adding additional weight to the exosomes by conjugating them with citrate-capped gold nanoparticles (CGNP). CGNPs were functionalized with polyethylene glycol (PEG) to form PEGylated GNP (PGNP). EDC/SNHS chemistry is used to activate the –COOH group of the PEG to make it suitable for conjugation with antibodies corresponding to exosomal surface proteins. These antibody-conjugated PGNPs were incubated with the serum to form PGNP-exosome complexes which were separated directly by centrifugation at a low g-force of 7000× g. This makes this technique efficient compared to that of standard ultracentrifugation exosome isolation (which uses approximately 100,000× g). Using the technique, the exosome isolation from serum was achieved successfully in less than two hours. The purification of small exosomes, characterized by the presence of CD63, CD9 and CD81, and sized between 20 nm to 50 nm, was confirmed by western blot, dynamic light scattering (DLS), transmission electron microscopy (TEM) and nanoparticle tracking analyser (NTA).

The steady rise in atmospheric long-lived greenhouse gas concentrations is the main driver of contemporary climate change. The Mauna Loa CO2 time series (1, 2), started by C. D. Keeling in 1958 and maintained today by the Scripps Institution of Oceanography and the Earth System Research Laboratory (ESRL) of NOAA, is iconic evidence of the effect of human-caused fossil fuel and land-use change emissions on the atmospheric increase of CO2. The continuity of such records depends critically on having stable funding, which is challenging to maintain in the context of 3- to 4-year research grant funding cycles (3), and is currently threatened by the financial crisis.The ESRL Global Monitoring Division maintains a network of about 100 surface and aircraft sites worldwide at which whole air samples are collected approximately every week for analysis of CO2, CH4, CO, halocarbons, and many other chemical species (4). This is complemented by high-frequency measurements at the Mauna Loa, Barrow, American Samoa, and South Pole observatories, and about 10 North American tall towers. The success of the NOAA program has inspired similar efforts in Europe (5), China (6), India (7), and Brazil (8), with the United Nations World Meteorological Organization providing guidance and precision requirements through the Global Atmosphere Watch program (9), but no funding.The data collected by NOAA and its worldwide partners have been used not only to demonstrate the unassailable rise of atmospheric greenhouse gas concentrations, but also to infer the magnitudes, locations, and times of surface-atmosphere exchange of those gases based on small concentration gradients between sites (10). Important findings from analysis of these records include the detection of a significant terrestrial carbon sink at northern mid-latitudes (11) and subsequent research aimed at identifying the mechanisms by which that sink must operate. Long-term, high-quality, atmospheric measurements are crucial for quantifying trends in greenhouse gas fluxes and attributing them to fossil fuel emissions, changes in land-use and management, or the response of natural land and ocean ecosystems to climate change and elevated CO2 concentrations.Greenhouse gas measurements along tall towers in the interior continents allow quantification of regional sources and sinks, which has a very high relevance for measuring the effectiveness of climate policy. NOAA ESRL provides measurements that are critical for the U.S. national security in that they provide independent verification and early warning of changing greenhouse gas emissions from countries involved in efforts to mitigate greenhouse gases.Dedicated carbon-observing satellites such as GOSAT and OCO-2 are needed to fill in the missing geographical information required for verification of carbon flux mitigation efforts. However, satellite retrievals do not yet provide sufficient information to deliver new constraints on surface fluxes, although quick progress is being made in this direction. In situ observations are crucial for anchoring space-borne measurements, for detecting potential biases of remote sensing techniques, and for providing continuity given the finite lifetime of satellites.Despite the growing importance of greenhouse gas observations to humanity, substantial budget cuts at NOAA have resulted in curtailment of our ability to observe and understand changes to the global carbon cycle. Already, a dozen surface flask-sampling sites have been removed from NOAA's operational network and aircraft profiling sites have been eliminated and reduced in frequency at the remaining NOAA sites. The planned growth in the tall tower program has stopped, and plans for closing some towers are being developed. The U.S. budget process in this election year, with the added risk of mandatory across-the-board cuts due to the 2011 Budget Control Act, foretells more bleak news for greenhouse gas monitoring at NOAA and could cause further retreat from the goal of recording ongoing changes in atmospheric composition. As scientists, we believe that preserving the continuity of these vital time series must remain a priority for U.S. carbon cycle research.