An efficient method for constructing a random insertional mutant library for forward genetics in Nannochloropsis oceanica

Insertional mutation,phenotypic evaluation,and mutated gene cloning are widely used to clone genes from scratch.Exogenous genes can be integrated into the genome during non-homologous end joining(NHEJ)of the double-strand breaks of DNA,causing insertional mutation.The random insertional mutant library constructed using this method has become a method of forward genetics for gene cloning.However,the establishment of a random insertional mutant library requires a high transformation efficiency of exogenous genes.Many microalgal species show a low transformation efficiency,making constructing random insertional mutant libraries difficult.In this study,we established a highly efficient transformation method for constructing a random insertional mutant library of Nannochloropsis oceanica,and tentatively tried to isolate its genes to prove the feasibility of the method.A gene that may control the growth rate and cell size was identified.This method will facilitate the genetic studies of N.oceanica,which should also be a reference for other microalgal species.

Semantic Consistency and Correctness Verification of Digital Traffic Rules

The consensus of the automotive industry and traffic management authorities is that autonomous vehicles must follow the same traffic laws as human drivers.Using formal or digital methods,natural language traffic rules can be translated into machine language and used by autonomous vehicles.In this paper,a translation flow is designed.Beyond the translation,a deeper examination is required,because the semantics of natural languages are rich and complex,and frequently contain hidden assumptions.The issue of how to ensure that digital rules are accurate and consistent with the original intent of the traffic rules they represent is both significant and unresolved.In response,we propose a method of formal verification that combines equivalence verification with model checking.Reasonable and reassuring digital traffic rules can be obtained by utilizing the proposed traffic rule digitization flow and verification method.In addition,we offer a number of simulation applications that employ digital traffic rules to assess vehicle violations.The experimental findings indicate that our digital rules utilizing metric temporal logic(MTL)can be easily incorporated into simulation platforms and autonomous driving systems(ADS).

The long-lived partial melting of the Greater Himalayas in southern Tibet, constraints from the Miocene Gyirong anatectic pegmatite and its prospecting potential for rare element minerals

The Cenozoic Himalayan leucogranite-pegmatite belt has been a hotspot for rare metal exploration in recent years.To determine the genesis of the pegmatite in the Himalayan region and its relationship with the Greater Himalayan Crystalline Complex(GHC),the Gyirong pegmatite in southern Tibet was chosen for geochronological and geochemical studies.The dating analyses indicate that the U-Th-Pb ages of zircon,monazite,and xenotime exhibit large variations(38.6‒16.1 Ma),with the weighted average value of the four youngest points is 16.5±0.3 Ma,which indicates that the final stage of crystallization of the melt occurred in the Miocene.The age of the muscovite Ar-Ar inverse isochron is 15.2±0.4 Ma,which is slightly later than the intrusion age,showing that a cooling process associated with rapid denudation occurred at 16‒15 Ma.TheεHf(t)values of the Cenozoic anatectic zircons cluster between−12 and−9 with an average of−11.4.The Gyirong pegmatite shows high contents of Si,Al,and K,a high Al saturation index,and low contents of Na,Ca,Fe,Mn,P,Mg,and Ti.Overall,the Gyirong pegmatite is enriched in Rb,Cs,U,K,Th and Pb and depleted in Nb,Ta,Zr,Ti,Eu,Sr,and Ba.The samples show a high 87Sr/86Sr(16 Ma)ratio of ca.0.762 and a lowεNd(16 Ma)value of−16.0.The calculated average initial values of 208Pb/204Pb(16 Ma),207Pb/204Pb(16 Ma)and 206Pb/204Pb(16 Ma)of the whole rock are 39.72,15.79 and 19.56,respectively.The Sr-Nd-Pb-Hf isotopic characteristics of the Gyirong pegmatite are consistent with those of the GHC.This study concludes that the Gyirong pegmatite represents a typical crustal‒derived anatectic pegmatite with low metallogenic potential for rare metals.The Gyirong pegmatite records the long‒term metamorphism and partial melting process of the GHC,and reflects the crustal thickening caused by thrust compression at 39‒29 Ma and the crustal thinning induced by extensional decompression during 28‒15 Ma.

Increased artemisinin production by promoting glandular secretory trichome formation and reconstructing the artemisinin biosynthetic pathway in Artemisia annua

Dear Editor,Artemisinin,which has potent antimalarial properties,is a sesquiterpene endoperoxide originally isolated from the traditional Chinese medicinal plant Artemisia annua.However,the artemisinin content in wild-type(WT)A.annua is low(1-10 mg/g dry weight),leading to its erratic supply and price fluctuations[1].

光响应聚赖氨酸-肉桂酸静电复合纳米自组装体

利用苄氧羰基赖氨酸-N-羧基环内酸酐(ZLys-NCA)开环聚合和脱保护,成功制备出聚乙二醇-聚赖氨酸(PEGPLL),并以反式肉桂酸作为小分子药物模型与聚赖氨酸静电复合,发现不同载药量的聚乙二醇-聚赖氨酸-肉桂酸(PEGPLL-tCA)能够自组装形成胶束和囊泡等不同的纳米结构。PEG-PLL-tCA静电复合系统在紫外(UV)光照射下聚合物侧链发生异构化,从而破坏自组装体的稳定性,具有光响应性和药物控释能力;研究了PEG-PLL-tCA的入胞性能,发现PEG-PLL-tCA比PEG-PLL有更好的细胞内在化性能。

故障模式下斜盘式轴向柱塞泵的流体振动传递路径分析

轴向柱塞泵是液压系统中的核心元件,其性能直接决定了整个系统的安全性和可靠性。而轴向柱塞泵故障也时常发生,最为常见的是三大摩擦副及轴承的失效故障。常常出现压力脉动、流量不达标、油液泄漏量大、壳体振动异常等多征兆问题,致使工作人员对其故障的溯源难以精准判别。但是轴向柱塞泵发生故障时壳体的异常振动对于各故障模式下其表现出来的时/频域曲线均不一致,所以本文对轴向柱塞泵正常及各种故障模式下进行流体振动产生机理及传递规律分析;建立柱塞泵流体振动传递路径模型及振动微分方程;利用MATLAB求解得到柱塞泵各模式下前、中、后壳体振动响应时/频域曲线,并提取典型故障特征信号。为轴向柱塞泵各故障模式下诊断提供理论依据。

A novel design of 3D carbon host for stable lithium metal anode

Rational design of porous conductive hosts with high electrical conductivity,large surface area,and adequate interior space is desirable to suppressing dendritic lithium growth and accommodating large volume change of lithium metal anode during the Li plating/stripping process.However,due to the conductive nature of the conductive hosts,Li is easily deposited directly on the top of the hosts,which hinders it from fully functioning.To circumvent the issue,in this study,we designed a novel porous carbon host with a gradient-pore-size structure based on one-dimensional(1D)carbon with different diameters.With this kind of host,stable cycling with high and stable Coulombic efficiency of~98%is achieved at 0.5 mA cm^(−2) with an areal capacity of 1 mAh cm^(−2) over 320 cycles.In contrast,the normal three-dimensional(3D)carbon nanotube host presents a moss-like Li morphology with wildly fluctuating Coulombic efficiency after 100 cycles.The results reveal that the unique gradient-pore-size structure of the 3D conductive host greatly improves the performance of lithium metal batteries.

NLRC3 alleviates hypoxia/reoxygenation induced inflammation in RAW264.7 cells by inhibiting K63-linked ubiquitination of TRAF6

Background:NOD-like receptor family CARD domain containing 3(NLRC3)plays an important role in both innate and adaptive immunity.This study was to explore the function and related mechanisms of NLRC3 in a hypoxia/reoxygenation(H/R)-induced inflammatory response in RAW264.7 cells.Methods:Liver ischemia-reperfusion(I/R)model in mice and H/R model in RAW264.7 cells were constructed.Western blotting was used to determine the protein expression level of NLRC3 in liver tissue and NLRC3,TRAF6,p–p65,p65,IκB–α,and the K63-linked ubiquitination level of TRAF6 in cells.The immunofluorescence assay was performed to evaluate the nuclear level of the NF–κB(p65).ELISA was conducted to measure the content of IL–1βin serum and cell supernatant.The interaction between NLRC3 and TRAF6 in cells was analyzed by the Co-IP assay.Results:The NLRC3 protein level in liver tissue was decreased with the prolongation of reperfusion time(P<0.05).The expression of NLRC3 and IκB–αprotein in RAW264.7 was decreased gradually,while the expression of p–p65 and TRAF6 proteins and K63-linked ubiquitination of TRAF6 were increased gradually with the prolongation of reoxgenation time(P<0.05).The Co-IP assay revealed that NLRC3 and TRAF6 can bind to each other directly.However,NLRC3 had no effect on the expression of TRAF6 protein.The ubiquitination test results showed that the K63-linked ubiquitination level of TRAF6 in H/R+Lv–NLRC3 group was significantly lower than that in the H/R+negative control(NC)group(P<0.05).Moreover,the activation of NF–κB in H/R+Lv–NLRC3 group was inhibited compared with that in the H/R+NC group,and the level of the inflammatory factor IL–1βin the cell culture supernatant was also decreased accordingly(P<0.05).Conclusions:NLRC3 might alleviate H/R-induced inflammation in RAW264.7 cells by inhibiting K63-linked ubiquitination of TRAF6.

Genome-wide identification of functional enhancers and their potential roles in pig breeding

Background:The pig is an economically important livestock species and is a widely applied large animal model in medical research.Enhancers are critical regulatory elements that have fundamental functions in evolution,development and disease.Genome-wide quantification of functional enhancers in the pig is needed.Results:We performed self-transcribing active regulatory region sequencing(STARR-seq)in the porcine kidney epithelial PK15 and testicular ST cell lines,and reliably identified 2576 functional enhancers.Most of these enhancers were located in repetitive sequences and were enriched within silent and lowly expressed genes.Enhancers poorly overlapped with chromatin accessibility regions and were highly enriched in chromatin with the repressive histone modification H3K9me3,which is different from predicted pig enhancers detected using ChIP-seq for H3K27ac or/and H3K4me1 modified histones.This suggests that most pig enhancers identified with STARR-seq are endogenously repressed at the chromatin level and may function during cell type-specific development or at specific developmental stages.Additionally,the PPP3CA gene is associated with the loin muscle area trait and the QKI gene is associated with alkaline phosphatase activity that may be regulated by distal functional enhancers.Conclusions:In summary,we generated the first functional enhancer map in PK15 and ST cells for the pig genome and highlight its potential roles in pig breeding.

Facilities for Centralized Isolation and Quarantine for the Observation and Treatment of Patients with COVID-19

The coronavirus disease 2019(COVID-19)pandemic increased the burden on many healthcare systems and in the process,exposed the need for medical resources and physical space.While few studies discussed the efficient utilization of medical resources and physical space so far.Therefore,this study aimed to summarize experiences related to facilities used for centralized isolation for medical observation and treatment during the COVID-19 pandemic in China and to provide suggestions to further improve the management of confirmed cases,suspected cases,and close contacts.In China,three types of facilities for centralized isolation(Fangcang shelter hospitals,refitted non-designated hospitals,and quarantine hotels)underwent retrofitting for the treatment and isolation of confirmed and suspected cases.These facilities mitigated the immediate high demand for space.Moreover,in order to minimize infection risks in these facilities,regulators and governmental agencies implemented new designs,management measures,and precautionary measures to minimize infection risk.Other countries and regions could refer to China’s experience in optimally allocating social resources in response to the COVID-19 pandemic.As a conclusion,government should allocate social resources and construct centralized isolation and quarantine facilities for an emergency response,health authorities should issue regulations for centralized isolation facilities and pay strict attention to the daily management of these facilities,a multidisciplinary administration team is required to support the daily operation of a centralized isolation facility,in-depth studies and international collaboration on the centralized isolation policy are encouraged.

The high diversity of SARS-CoV-2-related coronaviruses in pangolins alerts potential ecological risks

Understanding the zoonotic origin and evolution history of SARS-CoV-2 will provide critical insights for alerting and preventing future outbreaks.A significant gap remains for the possible role of pangolins as a reservoir of SARS-CoV-2 related coronaviruses(SC2r-CoVs).Here,we screened SC2r-CoVs in 172 samples from 163 pangolin individuals of four species,and detected positive signals in muscles of four Manis javanica and,for the first time,one M.pentadactyla.Phylogeographic analysis of pangolin mitochondrial DNA traced their origins from Southeast Asia.Using in-solution hybridization capture sequencing,we assembled a partial pangolin SC2r-CoV(pangolin-CoV)genome sequence of 22895 bp(MP20)from the M.pentadactyla sample.Phylogenetic analyses revealed MP20 was very closely related to pangolin-CoVs that were identified in M.javanica seized by Guangxi Customs.A genetic contribution of bat coronavirus to pangolin-CoVs via recombination was indicated.Our analysis revealed that the genetic diversity of pangolin-CoVs is substantially higher than previously anticipated.Given the potential infectivity of pangolin-CoVs,the high genetic diversity of pangolin-CoVs alerts the ecological risk of zoonotic evolution and transmission of pathogenic SC2r-CoVs.

A comparative study of name resolution and routing mechanisms in 网 information-centric networks

Information-Centric Networking (ICN) is an innovative paradigm for the future internet architecture, which addresses IP network limitations in supporting content distribution and information access by decoupling content from hosts and providing the ability to retrieve a content object by its name (identifier), rather than its storage location (IP address). Name resolution and routing is critical for content retrieval in ICN networks. In this research, we perform a comparative study of two widely used classes of ICN name resolution and routing schemes, namely flooding and Distributed Hash Table (DHT). We consider the flooding-based routing in Content-Centric Networks due to its wide acceptance. For the DHT scheme, we design a multi-level DHT that takes into account the underlying network topology and uses name aggregation to further reduce control overhead and improve network efficiency. Then, we compare the characteristics and performance of these two classes of name resolution and routing through extensive simulations. The evaluation results show that the performances of these two approaches are reliant on several factors, including network size, content location dynamics, and content popularity. Our study reveals insights into the design tradeoffs and offers guidelines for design strategies.

Establishing a protein expression profile database for the normal human pituitary gland using two-dimensional high-performance liquid chromatography combined with LTQ-Orbitrap mass spectrometry

In this study, we selected adult normal pituitary gland tissues from six patients during operations for pituitary microadenomas via the transsphenoidal approach for extended normal pituitary tissue resection around the tumor, and analyzed the protein expression of human normal pituitary using two-dimensional high-performance liquid chromatography combined with LTQ-Orbitrap mass spectrometry proteomics technology. The ten most highly expressed proteins in normal human pituitary were： alpha 3 type VI collagen isoform 5 precursor （abundance among tall pituitary proteins 1.30%）, fibrinogen beta chain preproprotein （0.99%）, vimentin （0.73%）, prolactin （0.69%）, ATP synthase, H~ transporting and mitochondrial F1 complex beta subunit precursor （0.52%）, keratin I （0.49%）, growth hormone （0.45%）, carbonic anhydrase I （0.40%）, heat shock protein 90 kDa I （0.31%）, and annexin V （0.30%）. Based on the biological function classifications of these proteins, the top three categories by content were neuroendocrine proteins （abundance among all pituitary proteins, 40.1%）, catalytic and metabolic proteins （28.3%）, and cell signal transduction proteins （9.8%）. Based on cell positioning classification, the top three categories were cell organelle （24.5%） membrane （20.8%）, and cytoplasm （13.0%）. Based on biological process classification, the top three categories of proteins are involved in physiological processes （42.9%）, cellular processes （40.4%）, and regulation of biological processes （9.1%）. Our experimental findings indicate that a protein expression profile database of normal human pituitary can be precisely and efficiently established by proteomics technology.

Effectiveness of ozonated saline in the treatment of VX2 tumors in rabbits

Objective To investigate the efficacy, safety, and associated mechanisms of injected ozonated saline in the treatment of VX2 tumors. Methods A total of 90 rabbits bearing VX2 tumors on their left hind legs were randomly divided into three groups. The control group(A) received normal saline, while groups B and C received 20 μg/mL and 40 μg/mL O_3/O_2 ozonated saline, respectively. Rabbits were anesthetized and 2 mL of blood was drawn directly from the heart to measure serum concentrations of interleukin(IL-6) and tumor necrosis factor(TNF-α). The skin covering the VX2 tumor was cut in each rabbit and the maximum and vertical diameters of the tumors were measured under direct visualization. Several milliliters of saline, saline pre-treated with 20 μg/mL O_3/O_2, or saline pre-treated with 40 μg/mL O_3/O_2 were directly injected into the tumors of groups A, B, and C, respectively(injection volume(milliliter) =1/2 volume of the tumor, V = 1/2ab^2). On days 4, 8 and 12 following treatment, 10 rabbits were randomly selected from each group for blood sample collection, and serum IL-6 and TNF-α were measured. The tumor growth rate was calculated by measuring the maximum and vertical diameters of the VX2 tumors under direct visualization. All selected rabbits were euthanized and the tumors, livers, and lungs were removed for pathological examination. The tumor necrosis rate was calculated by cutting the tumors into half along the longitudinal axis and measuring the maximum diameters of the intratumoral necrotic regions. Results The average tumor volume in the three groups increased to different degrees at each time point; however, the average tumor growth rates in groups B and C were substantially lower than that in group A, exhibiting a statistically significant difference. The difference in the tumor growth rate between group B and group C was not statistically significant. The serum concentrations of IL-6 and TNF-α increased in the three groups at each time point, with larger increases occurring in groups B and C; however, the greater increases did not reach statistical significance. Although the diameters of the necrotic areas were larger in both groups B and C than that in group A, significant differences in necrotic area diameters were only found when comparing groups A and C on days 4 and 12 following treatment. Conclusion Direct injection of different concentrations of ozonated saline into VX2 tumors significantly increased intratumoral necrosis and reduced the tumor growth rate. The associated mechanism may be partially mediated by IL-6 and TNF-α, as the serum concentrations of these molecules increased after the treatment.

AaWRKY17, a positive regulator of artemisinin biosynthesis, is involved in resistance to Pseudomonas syringae in Artemisia annua

Artemisia annua,a traditional Chinese medicinal plant,remains the only plant source for artemisinin production,yet few genes have been identified to be involved in both the response to biotic stresses,such as pathogens,and artemisinin biosynthesis.Here,we isolated and identified the WRKY transcription factor(TF)AaWRKY17,which could significantly increase the artemisinin content and resistance to Pseudomonas syringae in A.annua.Yeast one-hybrid(Y1H),dual-luciferase(dual-LUC),and electrophoretic mobility shift assay(EMSA)results showed that AaWRKY17 directly bound to the W-box motifs in the promoter region of the artemisinin biosynthetic pathway gene amorpha-4,11-diene synthase(ADS)and promoted its expression.Real-time quantitative PCR(RT-qPCR)analysis revealed that the transcript levels of two defense marker genes,Pathogenesis-Related 5(PR5)and NDR1/HIN1-LIKE 10(NHL10),were greatly increased in AaWRKY17-overexpressing transgenic A.annua plants.Additionally,overexpression of AaWRKY17 in A.annua resulted in decreased susceptibility to P.syringae.These results indicated that AaWRKY17 acted as a positive regulator in response to P.syringae infection.Together,our findings demonstrated that the novel WRKY transcription factor AaWRKY17 could potentially be used in transgenic breeding to improve the content of artemisinin and pathogen tolerance in A.annua.

Transport Patterns and Potential Sources of Atmospheric Pollution during the ⅩⅩⅣ Olympic Winter Games Period

The attainment of suitable ambient air quality standards is a matter of great concern for successfully hosting the ⅩⅩⅣ Olympic Winter Games(OWG). Transport patterns and potential sources of pollutants in Zhangjiakou(ZJK) were investigated using pollutant monitoring datasets and a dispersion model. The PM_(2.5) concentration during February in ZJK has increased slightly(28%) from 2018 to 2021, mostly owing to the shift of main potential source regions of west-central Inner Mongolia and Mongolian areas(2015–18) to the North China Plain and northern Shanxi Province(NCPS) after 2018.Using CO as an indicator, the relative contributions of the different regions to the receptor site(ZJK) were evaluated based on the source-receptor-relationship method(SRR) and an emission inventory. We found that the relative contribution of pollutants from NCPS increased from 33% to 68% during 2019–21. Central Inner Mongolia(CIM) also has an important impact on ZJK under unfavorable weather conditions. This study demonstrated that the effect of pollution control measures in the NCPS and CIM should be strengthened to ensure that the air quality meets the standard during the ⅩⅩⅣ OWG.

Characterization and chemical surface texturization of bulk ZnTe crystals grown by temperature gradient solution growth

Using tellurium as a solvent, we grew ZnTe ingots of 30 mm in diameter and 70 mm in length by a temperature gradient solution growth method. Hall tests conducted at 300 K indicated that the as-grown ZnTe exhibits p-type conductivity, with a carrier concentration of approximately 10^14cm^-3, a mobility of approximately 300 cm^2·V·s^-1, and a resistivity of approximately 10^2 Ω·cm. A simple and effective method was proposed for chemical surface texturization of ZnTe using an HF：H2O2：H2O etchant. Textures with the sizes of approximately 1μm were produced on {100}, {110}, and { 111}zn surfaces after etching. The etchant is also very promising in crystal characterization because of its strong anisotropic character and Te-phase selectivity.

Source,Characterization of Indoor Dust PAHs and the Health Risk on Chinese Children

Polycyclic aromatic hydrocarbons(PAHs)in indoor dust are one of the common exposure sources for children worldwide.The aim of this study is to explore PAHs pollution status in indoor dust and estimate health risk on Chinese children with big data.Weighted average concentration was used to analyze source and characterization of PAHs in indoor dust based on peer=reviewed literature.According to specific inclusion crteria,17 studies were included finally to analyze weighted average concentration.The national average concentration of ∑_(16)PAHs was approximately 25.696 ug/g.The highest concentration of ∑_(16)AHs was in Shanxi(2111.667 ug/g),and the lowest was in Hong Kong(1.505 μg/g).The concentrations in Shanxi and Guangdong were higher than national level and the over standard rate was 18.18%.The concentrations of individual PAHs varied greatly across the country,and Flu in Shanxi was the highest(189.400 μg/g).The sources of PAHs varied in different regions and combustion processes played a leading role.PAHs exposure through ingestion and dermal contact was more carcinogenic than inhalation.The incremental lifetime cancer risk model indicated that children lived in Shanxi were found in the highest health risk coupled with the highest BaPE concentration(54.074μg/g).Although PAHs concentrations of indoor dust showed a downward trend from 2005 to 2018,indoor environmental sanitation should be improved with multidisciplinary efforts.Health standard should be possibly established to minimize children exposure to PAHs in indoor dust in China.

早期食管病变内镜黏膜下剥离术后辅助治疗人群的预测模型

背景早期食管病变在无明显转移或浸润时均可以首选内镜下治疗,尤其是内镜黏膜下剥离术(endoscopic submucosal dissection,ESD),然而术后非治愈性切除、复发或转移等不良事件的发生是不可避免的,可能需要追加手术或放化疗等辅助治疗.目的分析ESD治疗早期食管病变后需要追加手术或放化疗的危险因素,并探讨治愈性切除对追加辅助治疗的影响.方法回顾性分析本中心因T1期食管癌及癌前病变行ESD者,随访患者术后复发、转移以及辅助治疗的情况,并建立辅助治疗人群选择的预测模型.结果患者年龄、病灶环周比例、镜下大小与ESD术后非治愈性切除相关(P<0.05),而且环周比例>2/3(OR=7.958,P=0.007)是独立危险因素.治愈性/非治愈性切除者中分别有2例/10例追加了手术或放化疗,即不论是否为治愈性切除均有辅助治疗者.年龄、环周比例、病灶抬举情况、分化情况、脉管侵袭、浸润深度等与ESD术后需要辅助治疗相关(P<0.05),年龄≥70岁(OR=4.210,P=0.049)、病灶抬举不良(OR=18.171,P=0.047)、浸润至SM2层(OR=38.781,P=0.012)是独立危险因素.列线图模型的曲线下面积为0.864(95%CI:0.766-0.962),特异度和灵敏度分别为95.8%和75.0%,校准曲线、决策曲线、Hosmer and Lemeshow检验(χ^(2)=1.5954,P=0.991)等显示该模型预测价值尚可.结论T1期食管癌及癌前病变者在ESD术后不能仅靠病理为非治愈性而追加手术或放化疗,而应结合患者情况、内镜表现及术后病理等综合评估.

Hop-by-hop Content Distribution with Network Coding in Multihop Wireless Networks

The predominant use of today＇s networks is content access and distribution. Network Coding （NC） is an innovative technique that has potential to improve the efficiency of multicast content distribution over multihop Wireless Mesh Networks （WMNs） by allowing intermediate Forwarding Nodes （FNs） to encode and then forward data packets. Practical protocols are needed to realize the benefits of the NC technique. However, the existing NC-based multicast protocols cannot accurately determine the minimum number of coded packets that a FN should send in order to ensure successful data delivery to the destinations, so that many redundant packets are injected into the network, leading to performance degradation. In this paper, we propose HopCaster, a novel reliable multicast protocol that incorporates network coding with hop-by-hop transport. HopCaster completely eliminates the need for estimating the number of coded packets to be transmitted by a FN, and avoids redundant packet transmissions. It also effectively addresses the challenges of heterogeneous mulficast receivers. Moreover, a cross-layer multicast rate adaptation mechanism is proposed, which enables HopCaster to optimize multicast throughput by dynamically adjusting wireless transmission rate based on the changes in the receiver population and channel conditions during the course of mulficasting a coded data chunk. Our evaluations show that HopCaster significantly outperforms the existing NC-based multicast protocols.